US3377599A - Electrosensitive recording apparatus - Google Patents

Electrosensitive recording apparatus Download PDF

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US3377599A
US3377599A US405800A US40580064A US3377599A US 3377599 A US3377599 A US 3377599A US 405800 A US405800 A US 405800A US 40580064 A US40580064 A US 40580064A US 3377599 A US3377599 A US 3377599A
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heat
layer
surface layer
temperature
base layer
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US405800A
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Charles S Reis
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HP Inc
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Hewlett Packard Co
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/20—Duplicating or marking methods; Sheet materials for use therein using electric current

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  • a very low voltage electrosensitive recording medium is produced by treating a conductive base layer disposed on backing material to form an ohmic contact between a surface layer of heat-sensitive material and the base layer. This overcomes the effects of any barrier layers which form between the base layer and the surface layer and presents sufiiciently high conductivity to applied writing signals to produce contrasting marks in response to applied wriling signals as low as 1 to 3 volts.
  • relative motion of the recording medium 9 with respect to the electrodes 11, 13 may be produced by moving the recording medium 9 and electrodes 11, 13 at dissimilar velocities.
  • Writing signals from source 15 are applied to the electrodes 11, 13 disposed in contact with the surface of recording medium 9 through switches 17, 19 which are actuated by writing controls 21, 23.
  • Contrasting lines or marks 25 are produced on the medium 9 in response to the writing signals as the electrodes pass along the surface.
  • the electrosensitive recording medium 9 is prepared according to one embodiment of the present invention as follows: aluminum is alloyed with indium in an amount typically of about 1 to percent but less than 20 percent by weight.
  • the alloy is vapor-deposited or laminated onto suitable backing material 27 such as paper or plastic film using well-known methods to form a thin conductive base layer 29.
  • suitable backing material 27 such as paper or plastic film using well-known methods to form a thin conductive base layer 29.
  • Other elements such as gallium, tin or other tri-valent electron donors may also be used in place of (or in addition to) the in
  • a conductive surface coating 31 comprising a heat: sensitive material which changes color at elevated temperatures is deposited on the base layer 29 using such conventional techniques as spraying or rolling.
  • the surface coating 31 may be prepared according to one embodiment of the present invention by combining grams of indium-doped zinc oxide which acts as a white pigment as well as an electrical conductor, 62.5 grams of a suitable binder such as Lucite No. 2040, 137 milliliters of a solvent such as xylene or toluene and 25 grams of heatsensitive substance formulated using four parts by weight of a heavy metal salt such as nickel acetate or nickel stearate to one part by weight of an alkaline earth metal sulfide such as calcium sulfide, barium sulfide or the like.
  • a heavy metal salt such as nickel acetate or nickel stearate
  • an alkaline earth metal sulfide such as calcium sulfide, barium sulfide or the like.
  • heat-sensitive substances may be formulated using 7.5 parts by weight of nickel palmitate, 2.5 parts by weight of barium or calcium sulfate and 1 part by weight of stearic or palmitic acid.
  • Still another heatsensitive substance may be formulated using 5 parts by weight of a stearate of a metal such as cobalt, copper, lead, magnesium, manganese, mercury, nickel or zinc and 1 part by weight of diphenylcarbozone.
  • a metal such as cobalt, copper, lead, magnesium, manganese, mercury, nickel or zinc
  • diphenylcarbozone any heat-sensitive material including azo, diazo and leuco dyes (the latter dye being less light-sensitive than the azo and diazo dyes) may be used in the surface coating material.
  • This coating material is rolled onto the base layer 29 to a wet thickness of about 3 mils and is dried at a temperature below the threshold value at which the color transiaion in the heat-sensitive material takes place.
  • the surface layer 31 thus formed comprises a matrix of heatsensitive and electrically conductive materials which are bonded to the base layer 29.
  • the base layer 29 which is an alloy of aluminum becomes coated with a discontinuous film of oxide when exposed to air during the fabrication process.
  • This oxide layer acts as an insulator which decreases the conductivity of the recording medium from the surface layer 31 to the base layer 29. This increases the amplitude of writing signal necessary to provide sufficiently high current density to produce a contrasting record on the surface layer.
  • the indium in the alloy base layer is believed to retard development of an oxide coating and to wet the contiguous surfaces of the base layer and surface layer through regions of discontinuity in the oxide film, thereby forming a low ohmic resistive contact between the two layers. A minute amount of diffusion of the indium into the surface layer is also believed to occur, thereby further increasing the conductivity of the ohmic contact.
  • the high conductivity of the recording medium thus reduces the-writing signal amplitude required to produce a contrasting record on the surface layer 31.
  • the writing signal amplitude required to produce a contrasting record may be reduced further according to one embodiment of the present invention by providing a biasing signal for the heat-sensitive surface layer.
  • a biasing signal for the heat-sensitive surface layer As is commonly known, leuco dyes and other mentioned heatsensitive compounds used in the surface layer 31 change composition, and hence, change color rather abruptly with temperature.
  • the surface layer 31 may be elevated in temperature by heating element 30 disposed near the electrodes 11, 13 to a temperature just below the threshold value at which the color transition in the dye occurs. This transition may occur typically within a 5 C. range so that the internal or joule heating provided by the writing signal need only produce a small increment in temperature.
  • electrosensitive recording may be achieved using the recording medium and apparatus of the present inventionwith writing signals levels, typically 100 may be due in part of a few volts at very low power milliwatts or less per electrode.
  • Recording apparatus comprising:
  • a base layer of conductive material including an alloy of aluminum and an element selected from the group comprising indium, gallium and tin;
  • a conductive surface layer disposed on said base layer and including a heat-sensitive material which changes color at elevated temperatures
  • said element diffusing into said surface layer to form an ohmic contact between said surface layer and said base layer;
  • a writing signal applied to said surface coating provides current flow therethrough with suflicient current density to elevate the temperature of local regions thereof to produce a color change in such regions.
  • said surface layer includes a heat-sensitive material selected from the group comprising azo, diazo and leuco dyes and a material which shows high electrical conductivity.
  • a conductive layer on said backing layer including an alloy of aluminum and iridium in a ratio of less than one part indium to four parts aluminum;
  • said surface layer including a heat-sensitive material selected from the group comprising azo, diazo and leuco dyes which change color at elevated temperatures;
  • a conductive surface coating disposed on said base layer and including a heat-sensitive material which changes color at elevated temperatures
  • a heat source disposed near said surface coating in a selected region for heating said surface coating to a temperature below the elevated temperature at which said heat-sensitive material changes color
  • an electrode connected to said source and disposed to apply a writing signal to said surface coating with sufficient amplitude to produce a current flow therethrough with sufiicient current density to increase the temperature of local regions of the surface coating near the electrode to a temperature above the elevated temperature at which said heat-sensitive material changes color, thereby to produce a contrasting record in such regions.
  • said heat-sensitive material in said surface layer is selected from the group comprising azo, diazo and leuco dyes.
  • Recording apparatus comprising:
  • a base layer including an alloy of aluminum and an element selected from the group comprising indium, gallium and tin;
  • a conductive surface coating disposed on said base layer and including a heat-sensitive material which changes color at elevated temperatures
  • said element being diffused into the surface coating to form an ohmic contact between said surface layer and said base layer;
  • a heat source disposed near said surface coating in a selected region for heating said surface coating to a temperature below the elevated temperature at which said heat-sensitive material changes color
  • an electrode connected to said source and disposed to apply a writing signal to said surface coating with sufiicient amplitude to produce a current flow therethrough with sufficient current density to increase the temperature of local regions of the surface coating near the electrode to a temperature above the elevated temperature at which said heat-sensitive material changes color, thereby to produce a contrasting record in such region.

Description

April 1968 c. s. REIS 3,377,599
ELECTROSENS ITI VE RECORDING APPARATUS Filed Oct. 22, 1964 WRITING 21 CONTROL WRITING r23 CONTROL HEAT SOURCE INVENTOR CHARLES S. REIS BY ac swag ATTORNEY United States Patent 3,377,599 ELECTROSENSITIVE RECORDING APPARATUS Charles S. Reis, Mountain View, Calif., assignor to Hewlett-Packard Company, Palo Alto, Calif., a
corporation of California Filed Oct. 22, 1964, Ser. No. 405,800 6 Claims. (Cl. 346-74) ABSTRACT OF THE DISCLOSURE of energy in the form of an applied electrical writing,
signal.
It is an object of the present invention to provide an improved electrosensitive recording medium which responds to lower voltage writing signals of the order of 1 to 3 volts.
It is another object of the present invention to provide an electrosensitive recording medium which may be biased below recording levels by a source of energy to decrease the power required in the writing signal to produce a recording.
It is another object of the present invention to provide an improved method of electrosensitive recording.
In accordance with the illustrated embodiment of the present invention, a very low voltage electrosensitive recording medium is produced by treating a conductive base layer disposed on backing material to form an ohmic contact between a surface layer of heat-sensitive material and the base layer. This overcomes the effects of any barrier layers which form between the base layer and the surface layer and presents sufiiciently high conductivity to applied writing signals to produce contrasting marks in response to applied wriling signals as low as 1 to 3 volts.
These and other objects of the invention will be apparent from a reading of this specification and an inspection of the accompanying drawing which shows electrosensitive medium and recording apparatus according to the present invention.
In the drawing, relative motion of the recording medium 9 with respect to the electrodes 11, 13 may be produced by moving the recording medium 9 and electrodes 11, 13 at dissimilar velocities. Writing signals from source 15 are applied to the electrodes 11, 13 disposed in contact with the surface of recording medium 9 through switches 17, 19 which are actuated by writing controls 21, 23. Contrasting lines or marks 25 are produced on the medium 9 in response to the writing signals as the electrodes pass along the surface. The electrosensitive recording medium 9 is prepared according to one embodiment of the present invention as follows: aluminum is alloyed with indium in an amount typically of about 1 to percent but less than 20 percent by weight. The alloy is vapor-deposited or laminated onto suitable backing material 27 such as paper or plastic film using well-known methods to form a thin conductive base layer 29. Other elements such as gallium, tin or other tri-valent electron donors may also be used in place of (or in addition to) the indium.
A conductive surface coating 31 comprising a heat: sensitive material which changes color at elevated temperatures is deposited on the base layer 29 using such conventional techniques as spraying or rolling. The surface coating 31 may be prepared according to one embodiment of the present invention by combining grams of indium-doped zinc oxide which acts as a white pigment as well as an electrical conductor, 62.5 grams of a suitable binder such as Lucite No. 2040, 137 milliliters of a solvent such as xylene or toluene and 25 grams of heatsensitive substance formulated using four parts by weight of a heavy metal salt such as nickel acetate or nickel stearate to one part by weight of an alkaline earth metal sulfide such as calcium sulfide, barium sulfide or the like.
Other heat-sensitive substances may be formulated using 7.5 parts by weight of nickel palmitate, 2.5 parts by weight of barium or calcium sulfate and 1 part by weight of stearic or palmitic acid. Still another heatsensitive substance may be formulated using 5 parts by weight of a stearate of a metal such as cobalt, copper, lead, magnesium, manganese, mercury, nickel or zinc and 1 part by weight of diphenylcarbozone. Of course, it will be appreciated by those skilled in the art that any heat-sensitive material including azo, diazo and leuco dyes (the latter dye being less light-sensitive than the azo and diazo dyes) may be used in the surface coating material.
This coating material is rolled onto the base layer 29 to a wet thickness of about 3 mils and is dried at a temperature below the threshold value at which the color transiaion in the heat-sensitive material takes place. The surface layer 31 thus formed comprises a matrix of heatsensitive and electrically conductive materials which are bonded to the base layer 29.
It is believed that the base layer 29 which is an alloy of aluminum becomes coated with a discontinuous film of oxide when exposed to air during the fabrication process. This oxide layer acts as an insulator which decreases the conductivity of the recording medium from the surface layer 31 to the base layer 29. This increases the amplitude of writing signal necessary to provide sufficiently high current density to produce a contrasting record on the surface layer. The indium in the alloy base layer is believed to retard development of an oxide coating and to wet the contiguous surfaces of the base layer and surface layer through regions of discontinuity in the oxide film, thereby forming a low ohmic resistive contact between the two layers. A minute amount of diffusion of the indium into the surface layer is also believed to occur, thereby further increasing the conductivity of the ohmic contact. The high conductivity of the recording medium thus reduces the-writing signal amplitude required to produce a contrasting record on the surface layer 31.
' The writing signal amplitude required to produce a contrasting record may be reduced further according to one embodiment of the present invention by providing a biasing signal for the heat-sensitive surface layer. As is commonly known, leuco dyes and other mentioned heatsensitive compounds used in the surface layer 31 change composition, and hence, change color rather abruptly with temperature. Thus the surface layer 31 may be elevated in temperature by heating element 30 disposed near the electrodes 11, 13 to a temperature just below the threshold value at which the color transition in the dye occurs. This transition may occur typically within a 5 C. range so that the internal or joule heating provided by the writing signal need only produce a small increment in temperature. Considerably less power per electrode is then required from the writing signal to elevate the temperature of record regions on the surface layer 31 above the transition temperature to produce a contrasting record. Thus electrosensitive recording may be achieved using the recording medium and apparatus of the present inventionwith writing signals levels, typically 100 may be due in part of a few volts at very low power milliwatts or less per electrode. This to the highly conductive ohmic contact formed between the base and surface layers by the indium in the base layer alloy and in part to the locally applied heat which biases the heat-sensitive material in the surface layer to a temperature just below the temperature at which the heat-sensitive material undergoes a color transition.
I claim:
1. Recording apparatus comprising:
a base layer of conductive material including an alloy of aluminum and an element selected from the group comprising indium, gallium and tin;
a conductive surface layer disposed on said base layer and including a heat-sensitive material which changes color at elevated temperatures;
said element diffusing into said surface layer to form an ohmic contact between said surface layer and said base layer;
whereby a writing signal applied to said surface coating provides current flow therethrough with suflicient current density to elevate the temperature of local regions thereof to produce a color change in such regions.
2. Recording apparatus as in claim 1 wherein said surface layer includes a heat-sensitive material selected from the group comprising azo, diazo and leuco dyes and a material which shows high electrical conductivity.
3. Recording apparatus comprising:
a backing layer;
a conductive layer on said backing layer including an alloy of aluminum and iridium in a ratio of less than one part indium to four parts aluminum;
a conductive surface layer disposed on said conductive layer;
said surface layer including a heat-sensitive material selected from the group comprising azo, diazo and leuco dyes which change color at elevated temperatures;
the indium in said conductive layer diffusing into said surface layer to form an ohmic contact between said surface layer and said conductive layer;
whereby a writing signal applied to said surface layer provides current flow therethrough with sufiicient current density to elevate the temperature of local regions thereof to produce a color change in such regions. I
4. Recording apparatus comprising:
a base layer of conductive material;
a conductive surface coating disposed on said base layer and including a heat-sensitive material which changes color at elevated temperatures;
a heat source disposed near said surface coating in a selected region for heating said surface coating to a temperature below the elevated temperature at which said heat-sensitive material changes color;
a source of writing signal; and
an electrode connected to said source and disposed to apply a writing signal to said surface coating with sufficient amplitude to produce a current flow therethrough with sufiicient current density to increase the temperature of local regions of the surface coating near the electrode to a temperature above the elevated temperature at which said heat-sensitive material changes color, thereby to produce a contrasting record in such regions.
5. Recording apparatus as in claim 4 wherein:
said heat-sensitive material in said surface layer is selected from the group comprising azo, diazo and leuco dyes.
6. Recording apparatus comprising:
a base layer including an alloy of aluminum and an element selected from the group comprising indium, gallium and tin;
a conductive surface coating disposed on said base layer and including a heat-sensitive material which changes color at elevated temperatures;
said element being diffused into the surface coating to form an ohmic contact between said surface layer and said base layer;
a heat source disposed near said surface coating in a selected region for heating said surface coating to a temperature below the elevated temperature at which said heat-sensitive material changes color;
a source of writing signal; and
an electrode connected to said source and disposed to apply a writing signal to said surface coating with sufiicient amplitude to produce a current flow therethrough with sufficient current density to increase the temperature of local regions of the surface coating near the electrode to a temperature above the elevated temperature at which said heat-sensitive material changes color, thereby to produce a contrasting record in such region.
References Cited UNITED STATES PATENTS 1,844,199 2/1932 Bicknell 346 X 2,680,062 6/1954 Sus 117-36.8 2,855,266 10/1958 James 346-76 X 3,089,952 5/1963 Wartman 11736.8 X 3,152,321 10/1964 Peltzer 34674 3,158,506 11/1964 Ellison 34676 X 3,167,444 1/1965 Baumann 11736.8 3,176,278 3/1965 Mayer 34674 3,299,433 1/1967 Reis 34672 BERNARD KONICK, Primary Examiner.
T ERRELL W. FEARS, Examiner.
L. SCHROEDER, Assistant Examiner.
US405800A 1964-10-22 1964-10-22 Electrosensitive recording apparatus Expired - Lifetime US3377599A (en)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3861952A (en) * 1971-01-30 1975-01-21 Sony Corp Recording medium for a spark burning recorder
US3864684A (en) * 1974-03-22 1975-02-04 Mitsubishi Paper Mills Ltd Multicolor electrothermic recording sheet
US4056823A (en) * 1976-12-03 1977-11-01 Xerox Corporation Analog chart recorder employing thermal printing means
US4309117A (en) * 1979-12-26 1982-01-05 International Business Machines Corporation Ribbon configuration for resistive ribbon thermal transfer printing
US4654677A (en) * 1982-04-07 1987-03-31 Hitachi, Ltd. Recording apparatus

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1844199A (en) * 1928-08-30 1932-02-09 Rca Corp Pyro-recording paper
US2680062A (en) * 1949-07-23 1954-06-01 Keuffel & Esser Co Process for the production of azo dyestuff images
US2855266A (en) * 1953-02-16 1958-10-07 Little Inc A Heat sensitive materials for recording instruments
US3089952A (en) * 1960-01-21 1963-05-14 Minnesota Mining & Mfg Method and means for thermographic reproduction
US3152321A (en) * 1961-04-12 1964-10-06 Litton Systems Inc High frequency transducing apparatus
US3158506A (en) * 1961-09-11 1964-11-24 Graphic Controls Corp Recording materials and their manufacture
US3167444A (en) * 1962-11-19 1965-01-26 Nashua Corp Heat responsive marking sheets
US3176278A (en) * 1958-04-22 1965-03-30 Litton Systems Inc Thermal method and system of magnetic recording
US3299433A (en) * 1964-10-21 1967-01-17 Reis electrosbnsitive recording

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1844199A (en) * 1928-08-30 1932-02-09 Rca Corp Pyro-recording paper
US2680062A (en) * 1949-07-23 1954-06-01 Keuffel & Esser Co Process for the production of azo dyestuff images
US2855266A (en) * 1953-02-16 1958-10-07 Little Inc A Heat sensitive materials for recording instruments
US3176278A (en) * 1958-04-22 1965-03-30 Litton Systems Inc Thermal method and system of magnetic recording
US3089952A (en) * 1960-01-21 1963-05-14 Minnesota Mining & Mfg Method and means for thermographic reproduction
US3152321A (en) * 1961-04-12 1964-10-06 Litton Systems Inc High frequency transducing apparatus
US3158506A (en) * 1961-09-11 1964-11-24 Graphic Controls Corp Recording materials and their manufacture
US3167444A (en) * 1962-11-19 1965-01-26 Nashua Corp Heat responsive marking sheets
US3299433A (en) * 1964-10-21 1967-01-17 Reis electrosbnsitive recording

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3861952A (en) * 1971-01-30 1975-01-21 Sony Corp Recording medium for a spark burning recorder
US3864684A (en) * 1974-03-22 1975-02-04 Mitsubishi Paper Mills Ltd Multicolor electrothermic recording sheet
US4056823A (en) * 1976-12-03 1977-11-01 Xerox Corporation Analog chart recorder employing thermal printing means
US4309117A (en) * 1979-12-26 1982-01-05 International Business Machines Corporation Ribbon configuration for resistive ribbon thermal transfer printing
US4654677A (en) * 1982-04-07 1987-03-31 Hitachi, Ltd. Recording apparatus

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