US3488664A - Ink transfer printer - Google Patents

Description

Original Filed April 21., 1965 a sheets-sheet 1 FIG. I

& -GATE CHARACTER DEFLECTION CHARACTER DECQDER MATRIX CIRCUITS I I 2 CODE INPUT 22 COLUMN. m WGATE SELECTOR FUNCTION DECODER INH CLOCK l3 6 CHARACTER TIMING INPUT 2 6'46 INVENTOR FIG 7 CHARLES R WINSTON FIG. FIG. FIG. I.

3 5 6 BY I .I I My ATTOR Rm. 8, mm c. R. wmsrcw INK TRANSFER PRINTER Original Filed April 21, '1965 s Sheets-Sheet 2 P/IS Jan. 6,

c. R. WINSTON 3,488,664

INK TRANSFER PRINTER Original Filed April 21, 1965 8 Sheets-Sheet 3 LINE FEED MECH.

BELL MECH.

c. R. wmsrow INK TRANSFER PRINTER Original Filed April 21. 1965 8 Sheets-Sheet 4 Jan. 6, 1970 c. a. wms'rom 3,488,664

INK TRANSFER PRINTER Original Filed April 21, 1965 8 Sheets-Sheet 5 Jan. 6, 1970 c. R. wmsrom' 3,438,664

v INK mmspnn PRINTER Original Filed Apr'il 21, I965 Sheets-Sheet s Jan. 6, 1970 ca. wmsmm 3,438,664

INK TRANSFER PRINTER Original Filed April 21, 1965 8 Sheets-Sheet 7 FIG. 8

FIG. IO

m Q FIG. 9

.Fm. 6, 1970 c. n. wmsmn 3,488,664

INK TRANSFER PRINTER Original Filed April 21, 1965 8 Sheets-Sheet a United States Patent 3,488,664 INK TRANSFER PRINTER Charles R. Winston, Deerfield, Il|., assignor to Teletype Corporation, Skokie, Ill., a corporation of Delaware Original application Apr. 21, 1965, Ser. No. 449,732, now Patent No. 3,432,844, dated Mar. 11, 1969. Divided and this application Feb. 16, 1968, Ser. No. 726,625

Int. Cl. GOld 15/16 US. Cl. 34675 8 Claims ABSTRACT OF THE DISCLOSURE This application is a division of copending application, Ser. No. 449,732, filed Apr. 21, 1965, now Patent No. 3,432,844.

This invention relates to character synthesis and more particularly to the synthesis of dot-matrix-formed charters by sequentially generating two-dimensional representations of the locations of the various dots going to make up each character.

Much ingenuity and considerable research have resulted in the development of mechanical and electromachanical printing devices to a relatively high degree of refinement with respect to printing speed, efficiency and reliability. The operating speed of these devices, however, is always limited by the inherent mechanical inertia of the component moving parts and by available power. The highest speeds for mechanical and electromechanical printers have been achieved by parallel operation, i.e., in such manner that an entire line of characters is printed simultaneously. Such operation, however, always entails storage of the entire line of information to be printed, resulting in additional equipment and increased complexity being introduced into the system. Serial operation, while not requiring such storage and not subject to the resultant limitations imposed thereby, dictates a far lower maximum printing speed. Thus, the need for a printing means capable of greater speed than the fastest mechanical system, but with serial operation, is manifest. Such a device may be employed, for example, for recording output data from an electronic computer, for accepting and recording information from a magnetic tape or drum or other type storage medium, or for recording telegraphic transmission as it is received one character at a time over a high-speed telegraph line.

Electronic methods of character synthesis are practically 'free of inertia and therefore inherently capable of serial type operation at very high speed. The present invention is therefore directed toward an improved apparatus and method whereby character synthesis may be accomplished in a serial type operation by means of a Patented Jan. 6, 1970 beam of marking material that is deflected from place to place within a printing field under control of the character synthesis system in order to trace or draw the desired character on the paper or other marking medium. Thus, in beam-type printing, a beam is used to control the deposit of ink on paper and becomes the pen with which the character is formed. This beam may be light, electrons in a vacuum tube, or a stream of charged ink droplets as disclosed in the patent to C. R. Winston No. 3,060,429, granted Oct. 23, 1962.

Synthesis of the character to be printed is usually on a dot-matrix pattern with the beam or marking source forming the character by moving from dot-location to dot-location tracing out the desired character. To control the tracing of the character, two-dimensional representations of the locations of the various dots which make up a character must be generated serially in the proper sequence.

It is an object of the present invention to synthesize a character for display 'by generating a sequence of twodimensional deflection signals.

Another object of the present invention is to control the generation of printed characters by converting coded input signal into a succession of pairs of deflection signals in a predetermined time sequence, each of the signals of a pair of deflection signals constituting the location or address which defines the coordinates of a dot in the character represented by the coded input signal.

Still another object of the invention is to control the deflection of a beam of ink droplets to print characters on a recording medium.

A further object of the invention is to control the defltction of an electrostatically-generated stream of ink droplets in order to locate each droplet in a selected sequence to form a character.

A still further object of the invention is to print page copy at high speed by providing a plurality of marking sources across a page and controlling their sequential operation.

Yet another object of the invention is to selectively energize one or more marking sources of a plurality of marking ray sources available.

In accordance with the preferred embodiment of the invention for controlling the deflection signals applied to the deflection electrodes of a printing device of the type disclosed in the aforementioned patent to C. R. Winston and for use in a high-speed telegraph page printer, a digital representation in a permutation code of the character to be printed is first applied simultaneously to a plurality of code input terminals. This code is monitored by a multiplicity of AND-gates. Certain of these AND-gates are used to decode and recognize nonprinting or function permutations, and the rest of these AND-gates begin the decoding process for the printed characters. At approximately the chronological center of the simultaneous pulses which carry the permutation code signal, a character-timing signal is received which triggers the completion of the decoding of the character then being received. Character recognition occurs by setting a plurality of ferrite switch cores. These switch cores are then reset one at a time. Each core is selectively wired with output windings; and as each core is reset, it generates a pulse over each of the output windings that have been threaded through it. This output is the digital representation in two dimensions of the location of one of the dots going to make up the character decoded. This digital representation of the dot location is then used to determine which of the previously-set cores is to be reset next. The last core to be reset signals the end of a character cycle and prepares the system for receipt of the next character.

To print a page width of visible copy, it is necessary that many of the printing devices shown in the aforementioned patent to C. R. Winston be used side by side. A column selector is used to determine which one or ones of the individual printing devices are operating at any given time. The signal which indicates the end of a printing cycle also causes the column selector to effect spacing of the printer by advancing operation of the printing devices such that the next character is printed in the next column to the right of the character just printed.

A more complete understanding of the invention may be had from the following description considered together with the accompanying drawings wherein:

FIG. 1 is a simplified logic block diagram of the character synthesis system;

FIGS. 2 to 6, inclusive, when arranged together in the manner illustrated in FIG. 7, form a detailed logic diagram of the character synthesis system shown in theblock diagram of FIG. 1;

FIG. 8 shows the input read-out and output arrangement of a typical ferrite core-type memory element used in the system;

FIG. 9 is a diagram of the dot-matrix printing field with the character B superimposed thereon;

FIG. 10 is a schematic diagram of the bistable multivibrator used in the synthesis system, showing the gating arrangement of the inputs to the multivibrator, and

FIG. 11 shows the digital-to-analog converters operating the deflection electrodes of the ink transferring device of the Winston patent.

GENERAL DESCRIPTION In the preferred embodiment of the invention as illustrated in FIG. 1, a character in the form of permutationcode electronic signals appearing simultaneously over a plurality of wires is applied to a code input 10. These simultaneous signals are carried to an AND-gate function decoder 11 and an AND-gate character decoder 12. In the format of a telegraph code, most of the signal permutations represent characters or figures to be printed; however, certain of the signal permutations represent nonprinting functions to be performed by the printer, such as spacing without printing (as is provided by the spacer bar on the typewriter), the ringing of a bell to signal an operator, carriage return to case the subsequent character to be printed at the left margin of the page, and line feed to move the page copy in order to begin printing on the next line, As soon as the character permutation signals are presented in the code input 10, the function decoder 11 begins recognition to determine whether or not that permutation code combination represents a nonprinting function. If the code combination is a nonprinting function, operation of the major portion of the character synthesis system is inhibited. At approximately the midpoint of the period of presentation of the pulses comprising the permutation code combination at the code input 10, a character timing signal is received over character timing input 13. This character timing signal indicates the optimum moment for recognizing the permutation code combination then being presented at code imput 10 and also provides a time base to which the remainder of the functions of the printer can :be referred. If the permutation code combination being presented at code input 10 is a nonprinting function, such as a line feed signal, the character timing signal is inhibited, by inhibitor 17, from energizing anything other than the function decoder; but the character timing signal initiates operation of the function. It the code combination presented at input 10 represents a character to be printed, decoding of this character begins immediately upon presentation of the coded signal to the AND-gate character decoder 12. Outputs 14 from the AND-gates 12 represent only a partially decoded character. These outputs 14 are combined in a character matrix 15 which, upon receipt of the character timing signal, uninhibited by recognition of a nonprinting function, completes the decoding of the character by setting a selected combination of switch cores contained in a dot core array 16, to their one state. This selected combination of switch cores represents that character being presented in permutation code form at code input 10, with each individual switch core representing one of the many dots which form the actual shape of the character on a dot-f0rmed-matrix type font.

The same character-timing signal which completes the decoding of the permutation code character also initiates operation of a local clock 20. This local clock 20 determines the rate at which dots are printed. As each core of the received character is reset to its zero state, the output of that core is presented over wires 23 to the deflection circuits 24 of the printer. This output is in the form of a digital representation in two dimensions of the location of the dot, associated with that core, in the dot matrix pattern of the character which is being printed. The deflection circuits 24 comprise digital-to-analog converters which change the digital signals to discrete voltage levels which are applied to the deflection electrodes of the ink transferring device disclosed in the Winston patent referred to hereinbefore.

This digital representation of the location of the dot is also sent to a dot-matrix 21 that determines which of the cores will be reset next. When the last core of the particular character being printed is reset, 9. signal is sent to the clock 20 to turn off the clock in order to prepare the printer for receipt of the next character. This same signal is also sent to the column selector 22 in order to cause the next character to be printed in the next space to the right.

In the patent to C. R. Winston mentioned above, disclosing apparatus for transferring ink, the device is shown printing characters on a strip of tape that is moved across the printing field of the device in order to permit each character to be printed in the same location with respect to the nozzle from which ink issues. If, however, it is desired to print material by this technique on a pagewidth of paper such as is done on a standard office typewriter, some provision must be made to either move the paper past the printing nozzle or to move the ink transfer device across the width of the paper. In page printing machines intended for unattended remote operation, it is common practice to move the page-width paper only longitudinally; that is, to move the paper in a vertical direction with respect to an operator reading the printed copy. The typing means is moved horizontally, while the paper is not; therefore, provision must be made for printing across a full -to-80-character line without moving the paper.

It has further been found that the ink transferring device considered herein can successfully print two adjacent characters without introducing excessive distortion of the character shape. In order to print two characters with a single nozzle, a large horizontal deflection is first imparted to the stream of ink droplets in order to locate the point of impingement of the stream of ink droplets onto the paper substantially to the left of the center line of the nozzle. A character is then printed which is totally to the left of the center line of the nozzle. After this character has been printed, a substational rightward deflection is imparted to the stream of ink droplets deflecting the stream of ink droplets to the right of the center line of the nozzle and printing a complete character wholly to the right of the nozzle center line. During idle periods of the stream of ink droplets, at which time it is not printing characters on the paper, a large vertical deflection is imparted to the stream deflecting it downwardly onto a mask which is provided in front of the paper and below the printing field. Since a single nozzle can effectively print two adjacent characters, an apparatus has been constructed using forty of the ink transferring devices of the Winston patent, spaced evenly across a page of a telegraph printer with such spacing between the nozzles that there is one nozzle for each two characters to be printed across the page of paper. Control must be provided for determining whether or not any given nozzle is printing to the left or right of its center line and the streams must also be controlled so as to determine which nozzle or nozzles are printing at any given time.

In controlling the sweep of a cathode-ray tube, the cathode-ray tube can be turned on and off by the grid of the cathode-ray tube without significant Worry over the effect of turn-on and turn-off transients; that is, irregularity of the display due to the fact that the cathode-ray is being turned on or turned off. It has been found that in the operation of the ink transfer device disclosed in the Winston patent significantly erratic operation of the stream of ink droplets was noted during the period in which flow of the stream of ink droplets was developing, such that unacceptable printing Was experienced. For this reason, a stream of ink droplets is first deflected downwardly onto the mask in front of the paper until the stream develops a steady-state flow pattern. At this point, once the ink flow pattern is fully developed, the stream is raised upwardly into the printing field and made to trace the character while maintaining a full rate of flow during the entire printing cycle. The stream can then be lowered onto the mask and turned off.

In printing at high speeds, the time required to develop a full flow of ink is sometimes sufficiently long that it is advantageous to turn on a stream long before it is to print a character and thus Warm up the stream. It is undesirable to have all of the stream turned on at all times since this wastes ink. Therefore, all the nozzles are turned off except when printing, and as printing is accomplished across the width of a page, each nozzle prints its two characters while the nozzle to its right is warming up and developing its pattern of flow. Therefore, at least two streams are flowing at any given time. Since the voltages involved in extracting a stream of ink droplets from a nozzle under negligible hydrostatic pressure are relatively large, a significant electrostatic field exists around each stream of ink droplets. In order to minimize the distortion of the character being printed by a given nozzle due to the effect of the electrostatic field generated by the nozzle to the right which is in the process of warming up, the preceding nozzle to the left of the printing nozzle is also permitted to remain in operation in order to provide a comparable electrostatic field to the left of the printing nozzle. Thus, it is desirable to maintain a flow of ink droplets from three adjacent nozzles simultaneously while at all times deflecting the streams from the outer two of these three nozzles onto the mask.

FUNCTION DECODER FIGS. 2, 3, 4, 5, and 6 when arranged according to FIG. 7 show a more detailed logic diagram of the character generator of FIG. 1. In FIG. 3 a six-unit or six-level permutation code signal is presented to the six inputs of code input 10. Each level of the code signal is inverted by one of the inverters 30 in order to produce a signal which is of the opposite binary sense or polarity of the associated code signal. This produces a permutation code signal on six pairs of Wires 35 with one wire of the pair carrying the bit which has been fed into the code input 10 and the other wire of the pair carrying a signal of opposite binary polarity. These six pairs of code signals existing on wires 35 are sent to the AND-gate function decoder 11 and the AND-gate character decoder 12a and 12b. The AND-gate function decoder 11 consists of four, five-input AND-gates. The AND- gates 40, 50, 55, and 58 of function decoder 11 are each selectively vw'red to five of the twelve wires 35 in order for each gate to recognize only one of the 64 possible permutations of the six-level code presented at code input 10. If a permutation code combination signal is received at code input 10, which represents spacing, in order to initiate a spacing function similar to that of the spacing bar on a typewriter, that code combination will energize AND-gate 40 of the function decoder 11 producing an output signal on spacing output wire 41. The signal on spacing output wire 41 performs two operations. This signal primes a spacing gated amplifier 42 and energizes a print-suppression OR-gate 45. The output of print suppression OR-gate 45 appears on print suppress-wire 46 and energizes inhibit gate 17 to prevent the recognition and printing of any printing character.

The pulses of the permutation code signal sent to code input 10 are of finite chronological duration. At the chronological center of these pulses, a character timing pulse is received at a character timing input 13. This character timing pulse is carried over character timing wire 47 to inhibit gate 17 and spacing gated amplifier 42. This character timing signal cannot pass through inhibit gate 17 due to the print suppression signal appearing on print suppress wire 46. However, the character timing signal on character timing Wire 47 does trigger spacing gated amplifier 42 in order to permit the spacing signal on spacing output wire 41 to pass through spacing gated amplifier 42 in order to cause the printer to space. The spacing function of the printer is similar to the spacing function in a typewriter with the exception that instead of spacing in response to actuation of the spacing bar of the typewriter, the printer spaces in response to receipt of a spacing signal as recognized by spacing AND-gate 40.

In the event that the code combination received the code input 10 is a carriage-return signal, carriage-return AND-gate 50 will be energized. The output of carriagereturn AND-gate 50 also performs two operations. This output energizes print suppression OR-gate 45 and primes carriage-return gated amplifier 51 which, like spacing gated amplifier 42, is triggered by a character timing signal appearing on character timing wire 47, causing a carriage return signal to appear on carriage return wire 52. When a signal appears on carriage return wire 52, it causes the next printed character received to be printed at the left-hand margin of the page much the same as on a typewriter. The spacing and carriage-return functions will be described more fully in conjunction with the column selector shown in FIG. 6.

In the event that the character received at character input 10 is a line-feed character, line-feed AND-gate 55 will be energized. The output of the line-feed AND-gate 55 operates the print-suppress OR-gate 45 and also energizes line-feed gated amplifier 56. Upon receipt of the character-timing signal over character-timing wire 47, this line feed signal is sent to the line feed mechanism 57 which causes the paper in the printer to advance, in order to print the succeeding character on the next line of the page copy. If the character received is a bell character, it will energize bell AND-gate 58 which functions the same as line-feed AND-gate 55 with the exception that it energizes bell-ringing mechanism 59 instead of linefeed mechanism 57.

AND-GATE CHARACTER DECODER At the same time that the AND-gate function decoder 11 is attempting to determine Whether or not the input character at code input 10 is a nonprinting function, the AND-gate character decoder 12 is attempting to decode this character as it appears on wires 35. These six pairs of wires making up wires 35 are broken down into two groups of three pairs each. One group of three pairs of wires is used to energize one group 12a of eight threeinput AND-gates and the other group of three pairs of wires is used to energize another group 1212 of eight three-input AND-gates. In a permutation code, three binary bits give rise to eight possible, distinct permutations; therefore, each group of three pairs of wires energizes a selected one of its associated group of eight AND- gates in response to any given permutation code combination. Since AND-gate character decoder 12 consists of two groups of eight AND-gates, one of the eight AND-gates of one of the groups when combined with one of the AND-gates of the other group, defines one of 64 possible combinations. The sixteen outputs from the AND-gate character decoder 12 are shown in FIG. 1 as outputs 14 and are shown providing the inputs to character matrix 15. The outputs 14a from the AND-gates 12a are used to prime gated amplifiers 65 while the outputs 14]) from AND-gates 12b provide the inputs for gated amplifiers 66. In the event that a non-printing function code combination is received at code input 10, print suppression wire 46 will carry a print-suppression signal and inhibit gate 17 will be energized. However, if a printing code combination is received at code input 10, there will be no print-suppression signal on wire 46, and the character timing pulse carried on wire 47 will pass through inhibit gate 17. The output of inhibit gate 17 performs two operations. This output starts the local clock which will be discussed in more detail below and is also sent over matrix trigger wire 67 to trigger the gated amplifier 65 that has been primed. Since only one of the gated amplifiers 65 has been primed by its associated AND-gate of AND-gates 12a only one of the matrix wires 68 will be energized. Similarly, since only one of the AND-gates 12b has been selected, only one of the orthogonal matrix wires 69 will be energized. A plurality of character diodes join the matrix wires 68 and orthogonal matrix wires 69. That diode which joins the energized one of the matrix wires 68 with the energized one of the orthogonal matrix wires 69 will conduct a pulse of current when matrix trigger wire 67 triggers gated amplifiers 65. This pulse of current completes the decoding of the code combination received at code input 10.

DOT CORE ARRANGEMENT The means by which the pulse of current passing through the selected diode of the core matrix 15 completes the decoding of the character is best explained in conjunction with FIG. 8 wherein there are shown three toroidal ferrite cores 75, 76, and 77 with a plurality of character wires 78 passing through the core in one direction. These character wires 78 are extensions of the leads of the character diodes of character matrix 15. If, for example, the character presented in coded form at code input 10 represented the letter B, AND-gates 83 and 84 (FIG. 2) would be energized. Gated amplifiers 85 and 86 would, upon occurrence of trigger pulses over matrix trigger wire 67, pass a large pulse of current through diode 82 of character matrix 15. The lead 78a of diode 82 is, in fact, far longer than shown in FIG. 2. Thus, lead or wire 78a is threaded through more of the dot core array 16 than merely cores 75, 76, and 77. Wire 78a is threaded through all of the ferrite cores of dot core array 16 that are used in the synthesis of the letter B. Therefore, when the large pulse of current passed through diode 82, it also passes through wire 78a which is threaded through all of the B cores and thus sets to their one state all of the cores used to synthesize a B. According to the right-hand rule of magnetic induction, a magnetic flux is thus induced to flow in cores 75, 76, and 77 in the direction of the arrow in response to the current pulse passing through wire 78a. At the proper time for core 75 to be interrogated, in order to deflect the stream of ink droplets to the location of the dot to be generated by core 75, a large pulse of current is sentthrough reset wire 90 and diode 91. It can be seen from FIG. 8 that this pulse of current, passing through reset wire 90 and diode 91, induces a flux to flow in core 75 in the opposite direction from the flux induced by the current pulse through wire 78a. This causes a reversal of the flux flowing through core 75, thus resetting core to its zero state. This flux reversal induces a voltage pulse across read-out wires 95, 97, and 98 which are threaded through core 75.

Read-out wires 95, 97, and 98 are selected ones of a complete set of read-out wires comprising wires 92 to 98, inclusive. Those read-out wires 95, 97, and 98 passing through core 75 carry the voltage impulses, generated by the flux reversal of ferrite core 75, to suitable utilization devices. The unselected read-out wires 92, 93, 94, and 96 carry no voltage pulses to their associated utilization devices since they do not pass through ferrite core 75.

The permutation of pulses appearing on wires 92 to 98 and forwarded to the utilization devices determines the deflection voltages to be applied to the deflection electrodes of the device disclosed in the patent to C. R. Winston mentioned hereinbefore. Wires 92 to 98 are thus selectively wired through all of the dot cores in core array 16 in different patterns to generate permutations corresponding to the locations of the several dots to be printed.

Each of the ferrite cores of dot core array 16 corresponds to a directed line segment or vector of the trace pattern of the particular dot within a character to which the core corresponds. Thus, core 75, for example, represents the vector beginning at the lowermost dot in the third column of dots counting from the left edge of the character, dot 99 in FIG. 9. The code generated in wires 92 to 98 by core 75, directs the jet of ink droplets to the adjacent dot 100 of the next column of dots in FIG. 9, the end of the vector. Therefore, while dot 99 is being printed, a pulse passes through wire and diode 91, which are the wire and diode corresponding to the location of dot 99, to read out or reset core 75 and generate a permutation signal on read-out wires 92 and 98 which directs the jet of ink droplets to dot 100. FIG. 9 shows the letter B in a prone position to correspond to dot matrix 21 of FIG. 5.

It can be seen that this movement of the stream of ink droplets from dot 99 to dot is not accomplished solely in the letter B but also in the letters D, E, F, K, L, and others. Therefore, in addition to the B wire 78a and B diode 82, wires 78b to f, inclusive, and associated diodes are shown as part of character wires 78, the others are omitted here for clarity. Therefore, whenever a B, D, E, L, F, or K, etc. is presented at code input 10, core 75 is set to its one state. And when core 75 is in its one state, and the stream of ink droplets is printing the dot 99, a current pulse passes through wire 90 and diode 91 and resets core 75 to its zero state generating the deflection permutation signals on read-out wires 92 to 98 which deflect the beam of ink droplets to dot 100. Wire 90 passes through all of those cores in dot core array 16 which could possibly be reset during the printing of dot 99, but in the case of the letter B, only core 75 is in its one state. The other cores through which reset wire 90 passes, are in their zero states and will generate no pulses on wires 92 to 98.

Similarly, wires 78c and 78a are the elongated leads of diodes 87 and 88 of FIG. 2 and may correspond to the characters K and L, for example. These wires 78c and 78d do not pass through core 77 since core 77 may not be necessary in the generation or synthesis of the characters K or L. However, wires 78g and 78h might be the leads of those diodes of diode matrix 15, which correspond to the letters T and Z, as shown in later examples.

Read-out wires 92 to 98 are connected to read-out amplifiers 102 to 108, respectively (FIG. 4). With the pulses generated on read-out wires 92 to 98 being amplified by read-out amplifiers 102 to 108 are used to drive individual binaries of shift register 110.

BISTABLE MULTIVIBRATOR At this point, there will be described the operation of. the individual binary or bistable multivibrator used in shift register 110 and elsewhere within the character synthesis system. FIG. 10 shows a schematic diagram of a typical bistable multivibrator suitable for use in this character generation logic system. The emitters of two transistors 120 and 121 are connected to one end of a resistor 122. Conventional feed-back voltage dividers are provided from the collector of each transistor to the base of the other transistor. Switching of the bistable multivibrator is accomplished by a positive-going transition of the voltage level of the condition appearing at any one of four possible trigger inputs 125 to 128. If the bistable multivibrator is already in the state desired, no change occurs; but if the bistable multivibrator is in the opposite condition, the voltage transition appears at the base of the then-conducting transistor in the form of a positive voltage pulse and drives the then-conducting transistor into its cutoff region. The positive-going transitions pass through capacitors 130 to 133 and blocking diodes 135 to 138, respectively. Since the character-generating system contemplates the use of many inputs on each bistable multivibrator and since it is desirable that not all trigger pulses be capable of triggering the bistable multivibrator, a gating or priming circuit is provided for each trigger input 125 to 128. The priming inputs 140 to 143 cooperate with their associated capacitors to provide RC coupling networks.

Referring specifically to the gate comprising terminals 125 and 140, for example, when a voltage input of 6 volts is provided at terminal 125, as well as at terminal 140, there is no voltage difference across the capacitor 130 and -6 volts appears at the anode of blocking diode 135. When a positive-going transition from 6 volts to volts is provided at terminal 125, 0 volts appears at the anode of blocking diode 135. This is inadequate to pass a current pulse through blocking diode 135 to drive transistor 121 into its cut-off region. If, however, terminal 125 is maintained at 6 volts and terminal 140 is maintained at 0 volts, a voltage difference of 6 volts appears across capacitor 130 and the anode of blocking diode 135 is maintained at 0 volts. When terminal 125 is suddenly changed to 0 volts, the voltage difference across capacitor 130 cannot be altered instantaneously; and +6 volts appears at the anode of blocking diode 135. Since blocking diode 135 cannot support a positive anode-to-cathode voltage, it conducts a current pulse, overcoming the feedback biasing circuit of the base of transistor 121, driving transistor 121 deep into its cut-off region.

Since the gating arrangement between terminals 125 and 140 is capacitive and resistive in nature, it results in a capacitor-storage of the previously applied priming voltage, which lasts for a few microseconds. A delay is thus experienced in establishing a new voltage difference across capacitor 130; therefore, a sudden change of priming input voltage at terminal 140 has no instantaneous effect upon the gating network. If a voltage change at the priming input 140 occurs simultaneously with a trigger signal (positive voltage transition) at terminal 125, the new priming voltage at terminal 140 is ineffective to determine whether or not transistor 121 is to be cut off; and the prior priming condition of terminal 140 therefore prevails.

By supplying a conjugated pair of signal-carrying wires to terminals 140 and 142, the bistable multivibrator of FIG. 10 is made to assume that signal condition of the conjugate pair of wires when a trigger pulse is received at both terminals 125 and 127. Only the trigger signal reaching a primed (0 volts) gate will pass through the associated blocking diodes. Any gate can be permanently primed so that any trigger pulse received by the gate will be passed through the associated blocking diode.

Similar gates are used at the inputs of the two monostable multivibrators 148 and 149 of the local clock 20 of FIG. 3. When bistable multivibrator 147 is set to its one state by a clock pulse from timing input 13 passing through inhibit gate .17, bistable multivibrator 147 sends a trigger pulse (positive-going transition) to continuouslyprimed trigger input 152 of monostable-multivibrator 148, setting it to its quasistable state. The steady state (0 volts) of this pulse from bistable multivibrator 147 then primes priming input 153 of another gate of monostable multivibrator 148. After a predetermined delay, monostable multivibrator 148 returns to its stable state and sends a trigger pulse (positive-going transition) over wire and also triggers monostable multivibrator 149 through a continuously-primed trigger input 154. After the predetermined interval of monostable multivibrator 149, it returns to its stable state and sends a trigger pulse over wire 151 and also triggers monostable multivibrator 148 through trigger input of the gate primed at priming input 153 by bistable mulivibrator 147. Therefore, as long as bistable multivibrator 147 stays in its one state and primes monostable multivibrator 148 at priming input 153, local clock 20 will continue issuing local clock timing pulses on wires 150 and 151. Each predetermined interval of one monostable-multivibrator constitutes a half-cycle of local clock 20.

DEFLECTION SIGNAL GENERATION Wires 92 to 98 of FIG. 8 are so connected to amplifiers 102 to 108 shown in FIG. 4 that the'permutation signals appearing on wires 92 to 98 are suitably amplified and used to drive their associated bistable multivibrators 112 to 118 of shift register 110. Shift register 110 is reset by the local clock pulse appearing on wire 151 at every cycle of local clock 20 so that each bistable multivibrator v112 to 118 is in its zero state prior to the interrogation of the next core of the dot core array 16. When the next core in the array is reset, the permutation signal generated on wires 92 to 98 sets, to their one state, those bistable multivibrators 112 to 118 of shift register 110 that are associated with the particular wires 92 to 98 which are threaded through the core just reset. F or example, in FIG. 8 wires 95, 97 and 98 are threaded through core 75; and when core 75 is reset to its zero condition, wires 95, 97, and 98 carry voltage pulses to their associated bistable multivibrators 115, 117, and 118 of shift register 110 while wires 92, 93, 94, and 96 of FIG. 8, which are not threaded through core 75, carry no pulses under these conditions. Since wires 95, 97, and 98 carry voltage pulses, amplifiers 105, 107, and 108 issue trigger pulses which are carried to continuously-primed trigger inputs of the multivibrators 115, 117, and 118 of shift register 110 setting bistable multivibrators 115, 117, and 118 to their one state while the other multivibrators of shift register .110 remain in their zero state having received no trigger pulses. There is a pair of outputs taken from each bistable multivibrators 112 to 118 of shift register 110; each pair of outputs contains one output at 0 volts (one state) and another output at -6 volts (zerd state) thus constituting a conjugate pair of outputs. These outputs are used to prime the input gates of the bistable multivibrators of shift register 160.

Referring now, for example, to bistable multivibrator 115 which is in its one state as a result of the resetting of core 75, wire is now at 0 volts and wire 171 is now at 6 volts. Conversely, bistable multivibrator 114 of shift register 110 is in its zero state since it did not receive a voltage pulse over Wire 94 from the resetting of the core 75. Output wire 172 of bistable multivibrator 114 is at 0 volts and output wire 173 is at -6 volts. Wires 170 and .171 are thus priming bistable multivibrator 165 of shift register 160 to assume its one state as soon as a trigger pulse is provided to its trigger inputs. Conversely, output wires 172 and 173 are priming bistable multivibrator 164 to its zero state.

When a trigger pulse passes wire 151 from local clock 20, it is suitably amplified by amplifiers 175 and 176. The output from amplifier 176 passes through OR-gate 177 and triggers each of the bistable multivibrators of shift register 160 to assume that state to which it is primed by its associated bistable multivibrator of shift register 110. The pulse issuing from amplifier 175 simultaneously resets all of the bistable multivibrators of shift register 110 to their zero state preparing shift register 110 for the interrogation of the next core. Due to the resistivecapacitive nature of the input gates of the bistable multivibrators of shift register 160, these gates possess a capacitively-stored priming feature which permits priming condition to persist for a few microseconds after the change of the priming voltage level; thus, the bistable multivibrators of shift register 160 assume the previous state of their associated bistable multivibrators of shift register 110 in spite of the fact that all of the bistable multivibrators of shift register 110 are reset to their zero states simultaneously with the triggering of the bistable multivibrators of shift register 160. The outputs from shift register 160 are used to energize the deflection circuits 24 in order to operate the ink transferring device disclosed in the patent to C. R. Winston mentioned above, and these outputs from shift register 160 are also used to determine which of the dot cores in core array 16 will be reset next. Location code wires 180 carry the pairs of signals taken from the bistable multivibrators of shift register 160 and deliver these signals to two sets of AND- gates 181 and 182 which are otherwise similar to AND-gates 12a and 12b of FIG. 2. Assuming, by way of example, that the outputs from shift register 160 presently deflect the beam of ink droplets to dot location 100 in FIG. 9 after the resetting of core 75. There is present in dot matrix 21 a single diode 186 which corresponds to dot location 100 of FIG. 9. Diode 186, upon the energization of AND- gates 183 and 184 and the issuance of a clock pulse over wire 150 from local clock 20 to gated amplifiers 185, passes a large pulse of current. Since diode 186 is the reset diode, the lead to which passes through core 76 of FIG. 8, this large pulse of current through diode 186 resets core 76 to its zero state generating pulses of current over wires 95, 96, and 98 threaded through core 76. In response to the pulses thus appearing on wires 92 to 98 amplifiers 105, 106, and 108 issue trigger pulses to bistable multivibrators 115, 116, and 118 of shift register 110. Upon the next half cycle of local clock 20, the pulse issuing on wire 151 transfers the information from shift register 110 to shift register 160 and simultaneously clears shift register 110. Bistable multivibrators 165, 166, and 168 are now in their one state while the remaining bistable multivibrators of shift register 160 are in their zero state. This condition passes over wires 23 and deflects the beam of ink droplets to dot location 191 of FIG. 9 by means of the deflection circuits 24 shown in greater detail in FIG. 11. This same signal passing over wires 180 energizes AND- gates 183 and 188. One-half cycle later, local clock 20 issues a trigger pulse over wire 150 which triggers gated amplifier 185 permitting amplifier 189 and gated amplifier 190 which are associated with AND- gates 188 and 183, respectively, to place a large pulse of current through diode 192. Diode '192 corresponds to dot location 191 in FIG. 9, and the elongated leads of diode 192 pass through all of those cores of dot core array 16 which correspond to the dot locations which could possibly follow dot location 100 in any character in the type font. However, only one of these cores, core 77, through which the leads of diode 192 are threaded has been set to its one state by the B wire 78a of diode 82 of the character matrix and only core 77 will be reset from its one state to its zero state by the pulse of current passing through the diode 192. Wires 94, 95, 96, and 98 pass through core 77 and thus carry a voltage pulse when core 77 is reset. It can be seen that the permutation signal thus carried by wires 92 to 98 deflects the stream of ink droplets to dot location 193 in FIG. 9. Dot location 193 could follow dot location 191 in the synthesis of the characters B, D, E, F, T, and Z, but not the characters K and L. Cores 75, 76, and 77 were described above as having been so wired.

,. Shift register is triggered once for each dot printed 70 and once more when the last core in the sequence is interrogated, in order to deflect the stream of ink droplets to an idle position out of the printing field. The letter B (FIG. 9) is made up of thirty-one individual dots; therefore, to print the letter B, shift register 160 must be triggered at least thirty-two times.

DEFLECTION DELAY In the ink transferring device disclosed in US. Patent No. 3,060,429, granted to C. R. Winston on Oct. 23, 1962, an ink droplet traveling from nozzle 13 to platen 11 in that patent requires a finite length of time to traverse this distance. The vertical deflecting electrodes 42 and 43 of the Winston patent are positioned closer to the nozzle 13 than are the horizontal electrodes 44 and 45 in FIG. 5 of the Winston patent. Therefore, an ink droplet proceeding from nozzle 13 of the Winston patent passes between vertical deflection electrodes 42 and 43 before it passes between horizontal deflection electrodes 44 and 45. In order to prevent smearing of the dots with which a character is formed, a change in the deflection signal applied to vertical deflection electrodes 42 and 43 must precede a change in horizontal deflection signal applied to horizontal deflection electrodes 44 and 45 of the Winston patent. This time difference between the changes applied to the two sets of deflection electrodes must be equal to the time required for an ink droplet to proceed from the vertical deflection electrodes to the horizontal deflection electrodes so that the change in deflection signals applied to these two sets of electrodes will effect the same droplet initially. Thus, the first droplet passing through vertical deflection electrodes 42 and 43 after a change in vertical deflection signal will also be the first droplet passing between horizontal deflection electrodes 44 and 45 of the Winston patent after a change in horizontal deflection signal.

Referring now to FIG. 4, bistable multivibrators 165, 166, 167, and 168 carry the vertical deflection signal and are connected directly to the deflection circuits 24 over wires 195 of wires 23. On the other hand bistable multivibrators 162, 163, and 164 carry the horizontal deflection signal and are not connected directly to the digital ttranalog converter but are used instead to prime an additional shift register 200. The priming and triggering of shift register 200 is similar to the priming and triggering of shift register 160 with the exception that the trigger pulse issuing from OR-gate 177 does not immediately trigger the bistable multivibrators of shift register 200. Instead, the pulse issuing from OR-gate 177 triggers a monostable multivibrator 205 to its quasistable state; thus, the clock pulse issuing from OR-gate 177 triggers each bistable multivibrator of shift register 160 to assume the state of its associated bistable multivibrator of shift register 110 and also triggers monostable multivibrator 205 to assume its quasistable state. At this point in time;

the vertical deflection signals from bistable multivibrators 165, 166, 167, and 168 pass immediately over wires 195 to the vertical digital-to-analog converters of deflection circuits 24 to generate the deflection voltages while the outputs from bistable multivibrators 162, 163, and 164 merely prime the inputs to the bistable multivibrators of shift register 200. After the predetermined delay of monostable multivibrator 205 has elapsed, this monostable multivibrator returns to its stable state sending a trigger pulse to all of the bistable multivibrators of shift register 200 setting them to the state to which they were primed by bistable multivibrators 1-62, 163 and 164 of shift register 160. The outputs of shift register 200 then proceed over wires 206 of wires 23 to the horizontal digital-toanalog converters of deflection circuits 24 to generate deflection voltages. Wires 23 from FIG. 4 are continued in FIG. 11 wherein wires 195 are shown going to the two vertical digital-to- analog converters 208 and 211, and wires 206 are shown as being connected to the two horizontal digital-to- analog converters 212 and 213. It

can be seen that half of wires 206 connect digital-toanalog converter 212 to the lower output terminals of the bistable multivibrators of shift register 200; and the other half of wires 200 from the upper output terminals of these same bistable multivibrators carry signals of the opposite binary sense or polarity to digital-to-analog converter 213. Since digital-to-analog converter 212 drives horizontal deflection electrodes 44 of the Winston patent (also shown in FIG. 11) through a suitable amplifier 214 herein and digital-toanalog converter 213 drives horizontal deflection electrodes 45 of the Winston patent through a suitable amplifier 215 herein, digital-to-analog converter 212 must develop a discrete voltage output equal to and opposite from the discrete voltage output developed by digital-toanalog converter 213. These discrete voltages are then added to the average voltage of horizontal deflection electrodes maintained by amplifiers 214 and 215 in order to keep the same average electrode voltage at the horizontal deflection electrodes, but maintain a voltage difference between the two horizontal deflection electrodes to deflect the stream of ink droplets. These opposite but equal, discrete voltage levels are obtained by driving the two digital-to- analog converters 212 and 213 by signals of the same but opposite binary sense.

Digital-to-analog converter 212 is drawn in greater detail in order to show the detailsof its operation. In converting from a digital to an analog signal, the permutation code digital input comprises several separate input wires maintained at one or the other of two voltages. In determining the output voltage level, some of the inputs must be given greater weight than others. This is accomplished by connecting a resistor in series with each input wire. The input wire to be accorded the greatest weight is connected to the lowest resistance R in order to pass the greatest amount of current for the given voltage of the binary input signals. The input having one-half as much weight is connected through a resistor of twice the resistance 2R in order to pass half as much current in response to the same voltage of the binary input signal. The output voltage to amplifier 214 is then proportional to the current flowing through the out-put resistor R END-OF-CHARACTER AND RESET In the generation or synthesis of a character, the last core of dot core array 16 to be reset must indicate to the system that a character is at an end. All of these cores of dot core array 16 which are the final cores in any given sequence of a character in the type font having wired through them a single stop wire 220 (FIG. 4) instead of permutations of wires 92 to 98. Therefore, while the last dot of the character is being printed, the diode in diode matrix 21 which corresponds to that dot location, passes a large pulse of current and resets the final core in the sequence to its zero state. This core, in resetting to zero, generates a voltage pulse on wire 220. The voltage pulse on wire 220 is suitably amplified by amplifier 221 and sets bistable multivibrator 222 to its one state. At the same time, this amplified pulse issuing from amplifier 221 passes over wire 223 and resets bistable multivibrator 147 (FIG. 3) to its zero state removing the priming condition from priming input 153 of monostable multivibrator 148 of local clock 20. The voltage pulse generated on wire 220 is generated in response to the pulse issuing from local clock 20 on wire 150; therefore, it can be seen that with the priming condition removed from priming input 153, the next pulse issuing from local clock 20 over wire 151 will not trigger monostable multivibrator 148 at its trigger input 155; thus, breaking the loop of operation and turning off local clock 20. This last pulse on wire 151, however, resets bistable multivibrator 222 to its zero state and simultaneously sets bistable multivibrator 224 to its one state as it is primed by bistable multivibrator 222.

Since this last core did not set any of the bistable multivibrators of shift register to their one state, shift register 160 is now completely idle with all of the bistable multivibrators of shift register 160 in their zero state. This condition is conducted over wires 23 to the deflection circuits operating the deflection electrodes, in order to deflect the stream of ink droplets downwardly below the normal printing field and onto a mask placed in front of the paper in order to prevent spurious ink marks on the paper. When bistable multivibrator 224 is in its one state, it primes gated amplifier 225. After monostable multivibrator 205 has timed its predetermined interval, it sends a pulse over wire 226 to trigger gated amplifier 225 sending a pulse over spacing wire 227 to effect spacing of the printer.

When shift register 160 is in its idle condition it selects AND-gates 182 and 230 (FIG. 5). The selection of these two AND-gates conditions dot matrix 21 to pass a pulse of current through diode 231 by triggering the gated amplifier associated with AND-gate 230 upon the issuance by local clock 20 of a pulse on wire at the beginning of the next character. The elongated leads of diode 231 pass through all of those cores of dot core array 16 which could possibly be the first core of any character. Therefore, as soon as the next pulse is presented to timing input 13 starting local clock 20, the first pulse issuing from wire 151 starts the sequence of character generation, resetting-the first core in the sequence by a large pulse of current through diode 231. In addition, the pulse applied to timing input 13 also passes over wire 235, through OR-gate 177 to reset shift register to assure that shift register 160 is in its idle condition and also to reset bistable multivibrator 224 to its zero condition in response to the zero" condition of bistable multivibrator 222. At this point, the character synthesis system is prepared to begin the next character.

SPACING Since there are forty nozzles across the width of the printer and each nozzle can print to the left or to the right, controls must be provided for determining which nozzles are emitting ink, which nozzle is printing, and whether it is printing to the left or to the right.

As described previously, at the end of one charactercycle of operation of the synthesis system, a pulse issues from gated amplifier 225 over spacing wire 227 in order to initiate spacing or column selection of the printer. This spacing signal passes through OR-gate 239 (FIG. 6) and triggers bistable multivibrator 240. Bistable multivibrator 240 is arranged to reverse its condition upon receipt of a trigger pulse from OR-gate 239 and therefore acts as a single-stage binary counter. The outputs of bistable multivibrator 240 are used to control the horizontal deflection of that stream of ink droplets that is printing at any given time in order to determine whether or not the stream is printing to the left or to the right of the nozzle center line. In order to determine whether the printing nozzle is deflected to the right or to the left of the nozzle center line, two outputs of opposite binary polarity are taken from bistable multivibrator 240 and are carried over wires 236 and 237. These outputs are shown in FIG. 11 going to digital-to- analog converters 212 and 213 to impart the major left-right swing to the stream of ink droplets. In the detail of digital-to-analog converter 212, Wire 236 is shown delivering one or the other of the two binary voltages through the lowest resistance 1/2R into digital-to-analog converter 212 in order to have the greatest weight in determining the level of the deflection voltage going into amplifier 214. After the left-hand character has been completed, the pulse traveling over wire 227 triggers bistable multivibrator 240 which in turn determines that the next character printed by the ink transferring device will be printed to the right of the nozzle center line. After this right-hand character has been completed, another pulse on wire 227 triggers bistable multivibrator 240' to again change 15 its condition and to determine that the succeeding nozzle prints the next character to the left of its center line, as will be described.

In order to space the printer without printing a character, a spacing function character is provided at code input 10 and is recognized by AND-gate 40. AND-gate 40 primes gated amplifier 42 so that when a timing signal is received at timing input 13, this timing signal travels over wire 47 and triggers gated amplifier 42. Upon being triggered, gated amplifier 42 sends a pulse over wire 232 to trigger monostable multivibrator 233 to its quasistable state. After the predetermined duration of monostable multivibrator 233, it returns to its stable state and sends a pulse over wire 234 to trigger bistable multivibrator 240 through OR-gate 239. The purpose of the delay of monostable multivibrator 233 is to provide the spacing trigger pulse to bistable multivibrator 240 over wire 234 at about the same time as a pulse would be sent over wire 227 if a character had been printed.

Another output of bistable multivibrator 240 is carried on wire 241 and is used to similarly trigger another bistable multivibrator 242 to assume its opposite condition after each complete excursion of bistable multivibrator 240. Since the outer two streams of ink droplets are always deflected downwardly onto the mask while the center stream is printing, in the preferred embodiment of the invention, the discrete vertical deflection signal issuing from vertical digital-to- analog converters 208 and 211 are used at any given time to drive only half of the forty ink transfer devices used in the page printer. Of these twenty ink transfer devices driven at any given time, ink is issuing from only one; therefore, only that one is printing. Alternate pairs of vertical deflection electrodes are driven together by the vertical digital-to- analog converters 208 and 211; thus, all of the even-numbered pairs of vertical deflection electrodes are driven together, and all of the odd-numbered pairs of vertical deflection electrodes are driven together. Bistable multivibrator 242 determines whether the even-numbered or the odd-numbered vertical deflection electrodes respond to the signals carried on wires 195 and that the non-responding vertical deflection electrodes direct their associated streams of ink droplets downwardly onto the mask.

In order to determine which set of deflection electrodes receive character-generating signals, two outputs of opposite binary polarity are taken from bistable multivibrator 242 and are carried over wires 244 and 245. These wires are shown in FIG. 11 as conducting these signals to suitable amplifiers 246 through 249. When wire 245 carries volts (one state), amplifiers 247 and 249 amplify and conduct deflection signals from digital-to- analog converters 208 and 249 to the vertical deflection electrodes of the ink transfer device of the Winston patent reproduced in FIG. 11. The same signals are carried to alternate ones of the other ink transferring devices, none of which are emitting ink. Since wire 244 carries 6 volts (zero state), amplifiers 246 and 248 determine that the vertical deflection electrodes of the ink transferring devices to which amplifiers 246 and 248 are connected deflect those of their associated streams of ink droplets that are flowing, downwardly onto the mask placed below and in front of the paper. Since each nozzle prints two adjacent characters, a change of vertical deflection amplifiers is accomplished only after the printing of every second character. The output of bistable multivibrator 240 on wire 241 is also amplified by amplifier 243. The output of amplifier 243 is used to turn on the next stream of ink droplets to the right and to turn off the last stream of ink droplets to the left; thus, stepping the on condition of the nozzles one step to the right.

In order to turn on three of the forty jets required to print across a page, it is necessary that the valving electrodes of each nozzle-corresponding to the control grids of cathode-ray tubes-be maintained at one or the other of two voltages, an on voltage or an off voltage. This can be done by the use of a 40-stage ring counter with the count advancing through the ring counter with three adjacent elements on at once. In order to conserve over half of these expensive ring counter elements, a matrix format has'been devised with AND-gates at the junction points of the matrices. The inputs of these matrices are provided by similar but smaller ring counters, the first of which comprises bistable multivibrators 250 to 257. Three adjacent bistable multivibrators are in their one state at any given time. The output of each element of this ring counter primes the next element in the ring and all elements are triggered simultaneously by the trigger pulse issuing from amplifier 243 in order to advance the three one" states one step in the ring. Bistable multivibrator 257 primes bistable multivibrator 250 in order to keep the three one states circulating. Another ring counter is provided which comprises bistable multivibrators 260 to 264. The outputs of these bistable multivibrators coact with the outputs of bistable multivibrators 250' to 253 to provide inputs to the first matrix 275 of two matrices of AND-gates. A third ring counter comprising bistable multivibrators 265 to 269 coacts with bistable multivibrators 254 to 257 of the first ring counter to provide the inputs for the second matrix 276 of AND-gates.

In order to begin a spacing operation at the left-hand margin of a page, a carriage-return signal is received at AND-gate 50 in FIG. 1. The pulse issuing from gated amplifier 51 passes over wire 52 and resets all three ring counters to their initial condition by triggering bistable multivibrators 250', 251, 252, 260, and 265 to assume their one state and by triggering bistable multivibrators 253, 254, 255, 256, 257, 261, 262, 263, 264, 266, 267, 268, and 269 to assume their zero state. With the three ring counters in this condition, AND-gates 280 281, and 282 of AND-gate matrix 275 are selected. These selected AND-gates provide on voltage to their associated outputs 285, 286, and 287 that are in turn connected to the control or valving electrodes of the leftmost three nozzles 291, 292, and 293 which are shown in FIGS. 6 and 11 along with several other of the valving electrodes to illustrate the relationship between the column selector circuits and the ink transferring device of the Winston patent.

In the leftmost condition, the nozzle associated with AND-gate 280 is a dummy, provided only to balance the electrostatic field for the nozzle associated with AND-gate 281 which is now prepared to print a character. The nozzle associated with AND-gate 282 is the next nozzle to print after the nozzle of AND-gate 281 has completed printing its right-hand character. After the nozzle of the AND-gate 281 has printed its right-hand character, the pulse appearing on wire 227 triggers bistable multivibrator 240 to cause the horizontal deflection amplifier system to print the left-hand character. Bistable multivibrator 240 triggers bistable multivibrator 242 to interchange'the function of the two vertical amplifier systems. This same pulse passes through amplifier 243 and triggers all of the bistable multivibrators 250-257 of the first ring counter. Each bistable multivibrator assumes the condition of the preceding bistable multivibrator. Therefore, bistable multivibrators 251, 252, and 253 are now in their one state energizing AND- gates 281, 282, and 283. After the nozzle of AND-gate 282 prints its lefthand character and then finishes printing its right-hand character, the first ring counter advances one step and energizes AND- gates 282, 283, and 284. As characters are printed across the page, the first ring counter continues to advance; and when bistable multivibrators 254, 255, and 256 are all energized, bistable multivibrator 253, upon changing state from one to zero, sends a trigger pulse over wire 290 to advance the energized condition in the second ring counter from bistable multivibrator 260 to bistable multivibrator 261. This prepares the second column of the first matrix 275 for operation while operation of the printer continues to be controlled by the first column Of he second matrix 276. In a similar manner, when bistable multivibrator 257 changes state from one to zero, bistable multivibrators 250, 251, and 252, are set to the one state, and a trigger pulse is supplied to the third ring counter to advance the energized condition in the counter from bistable multivibrator 265 to bistable multivibrator 266. Thus, control of the printing positions then is being eflected through the AND- gates in the second columns of the matrices 275 and 276. The ring counters continue to cycle from row to row and column to column in this manner until another carriage return character is received at the code input resetting the three ring counters to their original condition.

In order to provide the page printer with an automatic carriage return and line feed system, outputs from suitable ones of the bistable multivibrators of the three ring counters can readily be combined in an AND-gate which can be used to energize the resetting system in parallel with the carriage return AND-gate 50 and can also energize the line feed mechanism 57.

Although only one embodiment of the invention is shown in the drawings and described in the foregoing specification, it will be understood that invention is not limited to the specific embodiment described, but is capable of modification and rearrangement and substitution of parts and elements without departing from the spirit of the invention.

What is claimed is:

1. In an ink transferring apparatus for printing indicia on a record:

a plurality of ink transferring devices;

means for selectively rendering less than all of said ink transferring devices operable;

means for directing the ink issuing from less than all of the operable ink transferring devices onto the record and for guiding said ink, and

means for controlling said directing and guiding means to guide the ink to trace an indicium on the record.

2. In an ink transferring apparatus for printing indicia on a record:

a plurality of individual sources of streams of ink droplets;

means associated with each source for initiating operation of said source;

control means associated with each individual source for rendering its associated initiating means operative to cause a stream of ink droplets to flow from that source;

means for selectively energizing less than all of the control means at any one time to render less than all but more than one of the sources operative at any one time;

means for selectively deflecting some of the streams of ink droplets flowing from the operative sources out of impinging relationship with the record; and means for causing at least one of the flowing streams of ink droplets to print an indicium on said record.

3. In an ink transferring apparatus for printing indicia on a record:

a plurality of individual sources of streams of ink droplets;

means for selectively energizing less than all but more than one of the individual sources at a time for causing streams of ink droplets to flow only from the energized sources at any one time;

means for selectively deflecting at least some of the flowing streams of ink droplets out of impinging relationship with the record; and

means for deflecting at least one of the floWin-g streams of ink droplets into impinging relationship with the record for printing an indicium on said record.

4. In an ink transferring apparatus for printing indicia on a record:

a plurality of individual sources of streams of ink;

means for selectively energizing three or more adjacent sources at a time for causing said three or more adjacent sources to issue ink in streams directed toward the record;

means for deflecting at least one of the streams of ink out of impinging relationship with the record; and

means for directing at least one of the streams of ink onto the record for printing indicia thereon.

5. In an ink transferring apparatus for printing indicia on a record:

a plurality of individual sources of streams of ink;

a plurality of valving electrodes, each source having one associated valving electrode for controlling the volume of flow of ink in the stream of ink depending upon the voltage applied to the electrode;

a plurality of coincidence gates, each coincidence gate having two inputs and also two output voltage states with each gate associated with and connected to a valving electrode for turning the associated stream of ink on or ofl in response to signal applied to both of the inputs of the associated gate, and

means for selectively applying signals to both of the inputs of less than all of the gates at any one time thereby rendering less than all of the sources operative at any one time.

6. In an ink transferring apparatus for printing indicia on a record:

a plurality of individual sources of streams of ink;

a plurality of valving electrodes, each source having one associated valving electrode for controlling the volume of flow of ink in the stream of ink depending upon the voltage applied to the electrode;

a plurality of groups of coincidence gates, each gate having two inputs and also two output voltage states with each gate associated with and having its output connected to a valving electrode for turning the associated stream of ink on or oil? in response to different voltages obtained from the output of the associated gate;

a plurality of first signal sources, each first signal source being connected to one of the inputs of each gate of one of the groups of gates;

a plurality of second signal sources, each second signal source being connected to the other of the inputs of one gate of each group of gates;

means for energizing one of the second plurality of signal sources and at least one of the first plurality of signal sources for emitting signals whereby coincidence of signals from said signal sources causes energization of the gates to which the signals are applied whereupon the energized gates attain that output voltage state at which a stream of ink will issue from an individual ink source.

7. In an ink transferring apparatus for printing indicia on a record:

a plurality of individual sources of streams of ink;

a plurality of valving electrodes, each ink source having one associated valving electrode for turning the ink source on or off depending upon the voltage applied to the electrode;

a plurality of roups of coincidence gates each gate having two inputs and an output, the output of each coincidence gate connected to a valving electrode for controlling the voltage applied to said electrode;

a first ring counter, the output from each element thereof connected to one of the inputs of each gate of one of the groups of gates for selectively driving the inputs of said group of gates;

a second ring counter, the output from each element thereof conneted to the other of the inputs of a gate of each group of gates for selectively driving said gates; and

means for causing the first ring counter to advance one element for each complete cycle of the second ring counter, whereby coincidence of signals from the ring counters causes one or more of said gates to emit that References Cited output voltage state to its connected valving elec- UNITED STATES PATENTS trode, at which ink will issue from an associated individual source Winston 8. An ink transferring printer comprising: 3,136,594 6/1964 Ascoli 3461 a plurality of ink transferring stations; 5 1174;427 3/1965 Taylor 101-93 printing means at each station controllable for print- $298,030 1/1967 Lewls et 346-75 ing any of the characters of a font;

means associated with each station for preparatorily qualifying only that station to issue ink for transfer; 10 and means for activating the qualifying means in succession. 10193; 17830 JOSEPH W. HARTARY, Primary Examiner US. Cl. X.R.

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