WO2000030027A1 - Sensor and circuit architecture for three axis strain gauge pointing device and force transducer - Google Patents
Sensor and circuit architecture for three axis strain gauge pointing device and force transducer Download PDFInfo
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- WO2000030027A1 WO2000030027A1 PCT/US1999/027127 US9927127W WO0030027A1 WO 2000030027 A1 WO2000030027 A1 WO 2000030027A1 US 9927127 W US9927127 W US 9927127W WO 0030027 A1 WO0030027 A1 WO 0030027A1
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- Prior art keywords
- contact point
- strain gauges
- strain
- voltage
- perimeter
- Prior art date
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Classifications
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
- G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
- G06F3/02—Input arrangements using manually operated switches, e.g. using keyboards or dials
- G06F3/0202—Constructional details or processes of manufacture of the input device
- G06F3/021—Arrangements integrating additional peripherals in a keyboard, e.g. card or barcode reader, optical scanner
- G06F3/0213—Arrangements providing an integrated pointing device in a keyboard, e.g. trackball, mini-joystick
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
- G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
- G06F3/02—Input arrangements using manually operated switches, e.g. using keyboards or dials
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
- G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
- G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
- G06F3/033—Pointing devices displaced or positioned by the user, e.g. mice, trackballs, pens or joysticks; Accessories therefor
- G06F3/0338—Pointing devices displaced or positioned by the user, e.g. mice, trackballs, pens or joysticks; Accessories therefor with detection of limited linear or angular displacement of an operating part of the device from a neutral position, e.g. isotonic or isometric joysticks
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
- G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
- G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
- G06F3/033—Pointing devices displaced or positioned by the user, e.g. mice, trackballs, pens or joysticks; Accessories therefor
- G06F3/038—Control and interface arrangements therefor, e.g. drivers or device-embedded control circuitry
Definitions
- the present invention relates generally to pointing devices for use in connection with computers and other electronic instruments and devices. More specifically, the present invention relates to a pointing device used to move a pointer or cursor on a display of a computer or similar electrical or electronic device or instrument. Many operations relating to the use of modern computers, and in particular personal computers, require that a pointer or cursor be placed in a particular location on a display screen. In addition, many computer-operated and video games are operated based on positioning the cursor or pointing device in a particular location. In some applications, the position of the cursor may be governed by a touch pad, which is a small touch-sensitive pad embedded in the casing of the device or instrument.
- a joystick is used to control the movement of the cursor.
- this joystick may be a very small device positioned between several of the keys on the keyboard. The computer user manipulates such a small joystick by the end of the user's finger.
- the joystick may be somewhat larger, and be manipulated by the user grasping the entire joystick with the user's hand.
- Other applications may use joysticks of different sizes to manipulate a position indicator on the screen. The present invention will be described in connection with its application to joysticks.
- the position of the joystick, and its movement relative to its central "rest” or “neutral” position, should be identified so that such position information can be transferred to place the cursor at the appropriate spot on the computer screen or display.
- a variety of devices have been designed for detecting the position of a joystick.
- One particular mechanism for a pointing device is described in U.S. Patent No. 5,640,178 to Endo et al. This reference describes a joystick mounted on a resilient substrate. Strain gauges are formed on one surface of the substrate. A voltage is applied across a pair of the strain gauges in a particular direction, and the voltage at a half bridge output terminal between the strain gauges is measured. From this voltage, the amount of strain on each of the strain gauges of the pair may be determined.
- the present invention is a pointing device that measures strain on a substrate, and a method of operating such a pointing device.
- the strain gauges are configured as a series of voltage dividers across the substrate surface in a pattern that will allow the changes in the resistances of the strain gauges to be measured. From that determination, the position and displacement of the pointing device can be defined.
- a plurality of perimeter contact points is formed on the substrate surface, as is a plurality of strain gauges.
- Each strain gauge electrically connects a central contact point with one of the perimeter contact points.
- a controller circuit connected to a voltage source successively connects the voltage source across selected pairs of the perimeter contact points, and then detects the voltage at the central contact point between the strain gauges that are connected between the perimeter contact points across which the voltage source is connected. Different patterns of high and low voltages are connected to the perimeter contact points to establish the voltages across the different pairs of strain gauges.
- the strain gauges of the pointing device are formed of strain-sensitive ink applied to the substrate surface.
- a resistor having a known resistance is connected to the central contact point and the voltage is applied across that known resistance as well as the strain gauge resistances to determine a force applied along an additional axis.
- a resistor having a known resistance is connected in series with one of the pairs of strain gauges to measure the amount of strain when the strain gauges are stressed in the same direction. The voltage drop across each of the strain gauge resistors is measured to determine the force on each of the three axes.
- Figure 1 is a perspective view of a pointing device incorporating the present invention
- Figure 2 is a side elevational view of the pointing device illustrated in Figure 1
- Figure 3 A is a schematic diagram of the electrical circuit formed by a preferred arrangement of the strain gauge bridge structure of the present invention
- Figure 3B is a representation of a preferred physical arrangement of the strain gauge bridge structure of the present invention
- Figure 4 is a schematic representation of an electrical circuit formed by a second arrangement of the strain gauge bridge structure of the present invention
- Figure 5 is a schematic representation of an electrical circuit formed by a third arrangement of the strain gauge bridge structure of the present invention
- Figure 6 is a schematic representation of a first circuit architecture of the present invention
- Figures 7 A - 7D are schematic representations of operational configurations of the circuit architecture of Figure 6
- Figure 8 is a schematic representation of a second circuit architecture of the present invention
- Figure 9 is a schematic representation of a third circuit architecture of the present invention.
- the pointing device 21 includes a base 31 that may comprise a printed circuit board incorporating various circuit elements, as described below.
- a planar substrate 23 is suspended above the base 31.
- the substrate 23 is preferably formed of alumina, but it may also be formed of ceramic.
- the substrate 23 is preferably square, a shape that maximizes strength. Furthermore, the square shape optimizes space utilization by the strain gauge sensor arrays (as described below), thereby maximizing yields from existing alumina and ceramic plates that would be used for the substrate 23.
- a plurality of conductive solder contact pads 33 permit electrical contact between circuitry formed on the underside of the substrate 23 and circuitry formed on the base 31.
- a post or stick 25 projects from the upper side of the substrate 23.
- the stick 25 (which may be in the form of a joystick) forms the portion of the device 21 that may be manipulated (either directly or indirectly) by the user, and its movement from a predefined neutral position applies stress and/or strain to the substrate 23.
- an array 39 of strain gauges 41 , 42, 43, 44 is arranged on the lower surface of the substrate 23.
- the array 39 of strain gauges is applied to the surface of the substrate 23 that is opposite the surface from which the stick 25 projects.
- FIGS 4 and 5 respectively show a second strain gauge array 39a and a third strain gauge array 39b, both of which will be described in more detail below.
- Each array 39, 39a, 39b of strain gauges comprises a pattern of individual strain gauges.
- the pattern of strain gauges in the array is preferably symmetrical.
- the strain gauges 41-44 are arranged in a cruciform array, in pairs along each of the diagonals of the square substrate 23, and they are all substantially equidistant from the geometric center of the substrate 23.
- Each strain gauge constitutes a variable resistor, the resistance of which changes as a function of strain applied to the portion of the substrate 23 on which the strain gauge is located.
- a tensile strain may cause the resistance of a strain gauge to increase, while a compressive strain may cause the resistance of the strain gauge to decrease.
- the strain gauges are advantageously formed of strain-sensitive ink applied to the surface of the substrate. Suitable inks are well-known in the art.
- the other elements of the strain gauge array may be formed by applying conductive ink to the surface of the substrate. Referring, for example, to the embodiment illustrated in Figures 3A and 3B, four strain gauges 41 , 42, 43, and 44 are provided in a cross-shaped array 39.
- Figure 3 A illustrates the strain gauges 41, 42, 43, 44 schematically as variable resistors.
- Each strain gauge 41, 42, 43, 44 connects a central contact point 49 with a respective one of several perimeter contact pads 51, 52, 53, 54.
- the central contact point 49 may be formed as a contact on the surface of the substrate 23, or it may be formed on a circuit board (not shown) on the base 31. In the latter case, each of the strain gauges 41-44 would be electrically connected to the central contact point 49 by a discrete conductor, such as a contact pad or a wire (not shown).
- the central contact point 49 ( Figure 3A) is not on the substrate 23, but rather it is on the base 31.
- Each of the strain gauges is connected between its respective perimeter contact point and one of a plurality of secondary contact pads 55, each of which is electrically connected to the central contact point 49 on the base 31.
- the perimeter contact pads 51 , 52, 53, 54 and the secondary contact pads 55 are advantageously formed of a conductive ink, as are the connections between each of the contact pads and its respective strain gauge, and the connections among the strain gauges.
- the solder contact pads 33 ( Figure 1) may contact the perimeter contact pads 51, 52, 53, 54 and the secondary contact pads 55 of the substrate to provide electrical connection between the strain gauge array and the circuitry formed on the base board 31.
- First and second strain gauges 41, 42 along a first axis of the cross- shaped array 39 may be used to measure the strain caused in the substrate 23 by a movement of the stick 25 in the first axis (which for the purposes the following discussion may be described as the Y axis).
- Third and fourth strain gauges 43, 44 on the other (orthogonal) axis of the cross-shaped array 39 may be used to measure the strain caused in the substrate 23 by movement of the stick 25 in the orthogonal axis (which for the purposes of the following discussion may be described as the X axis).
- a tensile strain is applied to the second strain gauge 42, while a compressive strain may be applied to the first gauge 41.
- the compressive strain in the first strain gauge 41 will cause the resistance of the strain gauge 41 to change in one direction. For example, the resistance in the strain gauge under compression may decrease.
- the resistance of these second strain gauge 42 that is under tensile strain will change in the other direction. For example, the resistance of the second strain gauge under tensile strain may increase.
- a similar phenomenon is experienced by the strain gauges 43, 44 when the stick 25 is moved along the X axis. The change in strain gauge resistance will be substantially proportional to the distance that the stick 25 is moved from its neutral position.
- the magnitude of the stick's movement i.e., its distance from the neutral position
- the direction of movement is determined by which of the strain gauges along a particular axis increases in resistance and which decreases in resistance.
- the device can be configured to measure movement along a third (Z) axis orthogonal to the X axis and the Y axis (i.e., pe ⁇ endicular to the plane of the substrate).
- the strain gauge array of Figures 3 A and 3B is connected to control circuitry for selectively applying voltages to each of the perimeter contact pads 51, 52, 53, 54 of the strain gauge array 39, and for measuring outputs at others of the perimeter contact pads.
- Circuitry in the base 31 may include control circuitry such as the control circuitry shown in Figure 6.
- circuitry in the base circuit board 31 may connect the strain gauge array with control circuitry at another location. The control circuitry successively applies a voltage across different pairs of the strain gauges, and measures the voltage at the central point 49, to create a series of voltage dividers.
- FIGS. 7A to 7D voltage divider circuits are shown from which the changes in the resistances of the strain gauges 41 , 42, 43, 44 may be determined.
- FIGS. 7 A - 7D may be used with the control circuitry of Figure 6. Referring first to Figure 7 A, a voltage or potential is applied across the pair of Y axis strain gauges 41, 42.
- a high state may be connected to the first perimeter contact point 51 ( Figures 3 A, 3B), which is adjacent the first strain gauge 41, while a low state (ground) is connected to the second contact point 52 ( Figures 3A, 3B) adjacent the second strain gauge 42.
- the voltage at the central contact point 49 may be measured by detecting the voltage at one of the X axis perimeter contact points 53, 54 that are adjacent the orthogonal strain gauges 43, 44. In the schematic illustrated in Figure 7A, the voltage is detected at the perimeter contact pad 54 adjacent the strain gauge 44. This configuration produces a voltage divider across the Y axis strain gauges 41, 42.
- the voltage across the strain gauges 41, 42 may be reversed, with the high state V cc applied to the second perimeter contact point 52, and the low state (ground) applied to the first perimeter contact point 51. Measurement or detection of the midpoint voltage may again be taken off the fourth contact point 54.
- This configuration is shown schematically in Figure 7B. Taking the voltages measured at the central contact point 49 in the two voltage divider arrangements allows the relative values of the variable strain gauges 41 , 42 to be determined. By taking two voltage measurements at the fourth perimeter contact point 54, one for each polarity of the voltage applied across the Y-axis strain gauges 41, 42, the effect of the X-axis strain gauge 44 (through which the voltage at the central contact point 49 is measured) is essentially negated.
- the X axis strain gauges 43, 44 may be analyzed by applying a voltage across the X axis strain gauge pair 43, 44, and measuring the voltage at the central point 49 between them.
- a high state (Vcc) a y be applied to the third perimeter contact point 53 adjacent the strain gauge 43, and a low state (ground) may be applied to the fourth perimeter contact point 54.
- the voltage is detected at one of the other perimeter contact points, such as the first perimeter contact point 51.
- the voltage may then the reversed across the strain gauges 43, 44, as shown in Figure 7D.
- the control circuitry may perform this analysis on the strain gauges 41, 42, 43, 44 when the pointing device is first powered on, such as when the computer is initially turned on. If, at power-on, no pressure is being applied to the stick 25 of the pointer 21, the nominal, or "at rest,” values of the strain gauges 41, 42, 43, 44 may be determined.
- control circuitry may include a general pu ⁇ ose microprocessor 71 having a plurality of digital input/output ports P0, P 1 , P2, P3 , Q0, and Q 1.
- Each of the digital input/output ports P0 - P3 of the microprocessor 71 is connected to a corresponding one of the perimeter contact points 51, 52, 53, 54.
- the input/output port Q0 is connected to the fourth perimeter contact point 54 through a first fixed resistor 77
- the digital input/output port Ql is connected to the second perimeter contact point 52 through a second fixed resistor 79.
- the fixed resistors preferably have resistance values about 1.5 times the nominal (unstressed) resistance value of each of the strain gauge resistors 41 - 44.
- a summer 75 combines the states of some of the perimeter contact points and some of the digital input/output ports of the microprocessor 71 to produce a signal that can be inte ⁇ reted to determine the strain applied to the strain gauge elements 41 - 44.
- the states of the digital input/output ports P0, P3, Q0, and Ql of the microprocessor 71 are combined with the states of the perimeter contact points 52, 54.
- Some of the digital input/output ports of the microprocessor 71 are connected directly to the summer 75, while others are connected through fixed resistors.
- the digital input/output port Q0 is connected directly to a first input of the summer 75.
- the fourth perimeter contact point 54 is also connected to the first input of the summer 75 through the first fixed resistor 77.
- the digital port Ql is directly connected to a second input of the summer 75.
- the second perimeter contact point 52 is also connected to the second summer input through the second fixed resistor 79.
- the input/output port P3 and the fourth perimeter contact point 54 are connected to a third input of the summer 75 through a third fixed resistor 81.
- the input/output port P0 and the second perimeter contact point 52 are connected to a fourth summer input through a fourth fixed resistor 83.
- each of the third and fourth fixed resistors 81 , 83 has a resistance of approximately 2.5 times the nominal (unstressed) resistance of the strain gauge resistors 41 - 44.
- a digital to analog (D/A) converter 91 which may be a portion of the microprocessor 71, provides a negative the input to the summer 75.
- the output of the summer 75 is applied to an amplifier 93.
- the amplifier output is applied to an analog to digital (A/D) converter 95, which may be part of the microprocessor 71.
- An offset 97 may be a also applied to the amplifier 93 to compensate for any DC bias arising from mismatch among the individual components of the system.
- the circuit illustrated in Figure 6 may additionally provide measurement of a force applied to the stick 25 of the position control 21 in the Z axis (pe ⁇ endicular to the plane of the substrate 23, as seen in Figure 2).
- a Z axis force applied to the substrate 23 creates the same strain in the X axis strain gauges 43, 44 and in the Y axis strain gauges 41, 42, and the strain is in the same direction for all the strain gauges 41, 42, 43, 44.
- the Z axis force can be measured by placing a resistor in series with either the X axis strain gauges 43, 44, or the Y axis strain gauges 41, 42, and applying a voltage to both axes.
- One of the resistors 77, 79, 81, 83 may be used for this pu ⁇ ose.
- the strain applied in the Z direction to the strain gauge resistors 41 , 42, 43, 44 can be determined.
- the resistor 77 may placed in series with the X axis strain gauges 43, 44.
- the voltage drop across the resistor 77 can be measured through the electrical path connecting the perimeter contact point 54 with the summer 75 (through the resistor 81).
- the digital input/output ports P0 - P3, Q0, and Ql of the microprocessor 71 are set to successively establish the voltage divider configurations shown in Figures 7 A - 7D. To set those voltage dividers, the digital input/output ports P0 - P3, Q0, and Ql of the microprocessor 71 are set to the following states:
- V cc relatively high voltage
- ground relatively low voltage
- R high impedance
- the microprocessor 71 may be programmed to selectively set the microprocessor input/output ports P0 - P3, Q0, and Ql in the appropriate states.
- the microprocessor 71 has an output port 99, which may be any of several conventional microprocessor output ports.
- the port 99 may be a PS/2 port, an RS232 port, or a Universal Serial Bus. Other types of output ports will become apparent to those skilled in the art.
- the microprocessor 71 compares the voltage value received with a voltage value stored in the non- volatile memory of the microprocessor 71 that is read on power-up, or at another time when no strain is placed on the pointing device. From this comparison, the microprocessor 71 calculates the changes in the resistances of the Y axis strain gauges 41, 42. From these changes, the microprocessor 71 can, using conventionally known procedures, determine the stresses being applied to the stick 25 of the cursor control 21 in the Y axis. From these stresses, the microprocessor 71 can then further determine the appropriate position along the Y axis for the cursor or other pointing device.
- a succession of signals indicative of the voltage at the central contact point 49 is applied through the summer 75 to the microprocessor 71.
- the microprocessor 71 compares the voltage value received with a voltage value stored in the non- volatile memory of the microprocessor 71 that is read on power-up, or at another time when no strain is placed on the pointing device. From this comparison, the microprocessor 71 calculates changes in the resistances of the X axis strain gauges 43, 44. From these changes, the microprocessor 71 can determine, using conventionally known procedures, the stresses being applied to the stick 25 of the cursor control 21 in the X axis.
- the microprocessor 71 can then further determine the appropriate position along the X axis for the cursor or other pointing device.
- An alternative circuit for measuring a Z axis force applied to the pointing device is shown in Figure 8.
- contact is provided directly to the central contact point 49 of the strain gauge array. This direct contact allows direct measurement of the voltage division across the strain gauges 41 - 44.
- the central contact point 49 is connected to the input of an amplifier 101.
- the output of the amplifier 101 is applied to an analog to digital converter 103 for use by a microprocessor 105.
- the analog to digital converter 103 may form a portion of the microprocessor 105.
- the microprocessor 105 has a plurality of digital input/output ports 107, individually labeled P0 ⁇ P4. These digital input/output ports 107 are successively set to high and low voltages, and to high impedance to set up the series of voltage dividers.
- An external known (and generally fixed) resistor 108 is connected directly between the central contact point 49 and one of the digital input/output ports 107 (i.e., P4) of the microprocessor 105.
- This additional resistor 108 provides an additional bridge in the strain gauge array that may be measured.
- a fifth voltage divider can be set up across the additional fixed resistor 108 by appropriately controlling the digital input/output port P4 of the microprocessor 105.
- the voltage divider across the one of the Y-axis strain gauges (e.g., the strain gauge 42), one of the X-axis strain gauges (e.g., the strain gauge 44), and the external fixed resistor 108 allows the Z axis force to be determined.
- the high voltage (V cc ) may be applied to the strain gauges 42 and 44 simultaneously.
- the external resistor 108 may be connected between the central contact point and a very low potential (such as ground). By measuring the voltage at the central contact point, between the strain gauges 42 and 44 and the external resistor 108, a voltage divider is established.
- the digital input/output ports 107 are used to switch among a high voltage (V cc ), ground, and high impedance states around the array of strain gauges 41 - 44.
- the microprocessor 105 may generate an offset signal to compensate for differences among the values of the individual resistors 41 - 44 of the strain gauge array. This offset signal is converted to an analog signal in a digital to analog converter 109, which may also be a portion of the microprocessor 105. The analog offset signal is applied to the amplifier 101.
- FIG. 4 illustrates a triangular arrangement of strain gauge variable resistors 141, 142, 143, each connecting a central contact point 149 with one of three perimeter contact points 151, 152, 153.
- a fixed resistor 144 connects the central contact point 149 with a fourth perimeter contact 154.
- a known voltage V cc may be connected to the fourth perimeter contact 154, and a series of voltage dividers may be created that divide a known voltage across the fixed resistor 144 and, in succession, the variable resistances of the strain gauges 141, 142, 143.
- the midpoint voltage at the central contact point 149 is detected on a fifth perimeter contact 155. From such a series of voltage dividers, the resistances of the strain gauges 141, 142, 143 may be measured, and the strain applied to each of the strain gauges determined. From this information, the appropriate position for the cursor control may be determined.
- a known voltage V cc may be applied to the fourth contact point 154 that is connected to the fixed resistor 144.
- the second and third perimeter contacts 152, 153 may be connected to high impedances, and the first perimeter contact 151 may be connected to a high potential through a low impedance.
- the voltage divider is set up across the fixed resistor 144, and the first strain gauge variable resistance 141.
- the output voltage at the cenfral contact point 149 forming the midpoint of the voltage divider is measured at the fifth perimeter contact 155. From the known resistance of the fixed resistor 144, the value of the variable resistor 141 may be determined. Similar voltage dividers may successively be set up for the second and third strain gauges 142, 143.
- the strain gauge array 39a of Figure 4 is connected to control circuitry for establishing the voltage dividers described above.
- the known voltage V cc is supplied to the fourth perimeter contact point 154 of the strain gauge array 39a through a digital input/output port P3 of a microprocessor 105a.
- the perimeter contact points 151, 152, 153 of the strain gauge array are connected to the digital input/output ports P0, PI, P2, respectively, of the microprocessor 105a.
- the digital input/output ports P0, PI, P2 are selectively set to establish the voltage dividers across the three strain gauges 141, 142, 143.
- the fifth perimeter contact point 155 is connected to the input of a summing amplifier 101. An offset may be applied to the amplifier 101 from the microprocessor 105 a through a digital to analog converter 109.
- the output of the amplifier 101 is applied to be microprocessor 105a through an analog to digital converter 103.
- the strain measured in each of the triangular legs of the array illustrated in Figure 4 can be converted to X and Y axis values, or other appropriate coordinates.
- the triangular arrangement of the strain gauges is symmetrical, with a 120 degree angle between each of the strain gauge legs.
- a third strain gauge array 39b is illustrated in Figure 5, which illustrates a triangular array of three strain gauges 241, 242, 243.
- Each of the strain gauges 214, 242, 243 connects a central contact point 249 with one of three perimeter contact points 251, 252, 253.
- a series of voltage dividers may be established across successive pairs of the strain gauges 241, 242, 243. It will be recognized that control circuitry similar to that shown in Figure 9 may be configured to set up such a series of voltage dividers.
- the stresses measured on each leg of the array can be converted to an appropriate coordinate system.
- the systems and methods described above may consume less power than many existing systems and methods for pointing devices. Using the systems and methods described above, the pointing device and its controller circuitry need not be powered at all times, but need only be powered at times that measurements are being taken.
- the power is switched around the various contact points on the substrate, to successively power the different strain gauges, so that not all contact points need to be continuously powered.
- An additional advantage of the apparatus and methods described above is that automatic gain adjustment can be achieved by simply correcting the amplifier offset through the analog output feedback from the microprocessor 71 to the amplifier 93 (in the Figure 6 embodiment).
- a further advantage of the systems and methods described above is that the square, triangular, or other regular shape of the strain gauge array permits the substrate 23 to be manufactured in a similarly regular shape. Such regular shaped substrates are easier to manufacture than the intricate shapes often required with other pointing devices. Finally, using appropriate electronic techniques (including calculations by the microprocessor), differences in the specific characteristics of the strain gauges may be accounted for.
- the strain gauges need not exactly match one another, and expensive laser trimming of the strain gauges to match them is not necessary.
- modifications may be made to the particular embodiments described above without departing from the invention.
- other arrangements of the strain gauges on the substrate may be made, and different substrate materials may be used.
- other types of control circuitry may be used.
- the device 21 can be configured for use as a force transducer, with the control circuit employing a microprocessor that is programmed to yield a force-indicative output signal in response to the sensed displacement of the stick 25. Therefore, the particular embodiments described above are considered exemplary, and should not be considered limiting. Rather, the scope of the invention is defined in the claims that follow.
Abstract
Description
Claims
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP99972337A EP1131781A1 (en) | 1998-11-18 | 1999-11-16 | Sensor and circuit architecture for three axis strain gauge pointing device and force transducer |
KR1020017006103A KR20020001708A (en) | 1998-11-18 | 1999-11-16 | Sensor and circuit architecture for three axis strain gauge pointing device and force transducer |
JP2000582963A JP2002530755A (en) | 1998-11-18 | 1999-11-16 | Structure of sensor and circuit for 3-axis strain gauge position indicating device and force transducer |
CA002345413A CA2345413A1 (en) | 1998-11-18 | 1999-11-16 | Sensor and circuit architecture for three axis strain gauge pointing device and force transducer |
AU14788/00A AU1478800A (en) | 1998-11-18 | 1999-11-16 | Sensor and circuit architecture for three axis strain gauge pointing device and force transducer |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/195,345 | 1998-11-18 | ||
US09/195,345 US6243077B1 (en) | 1998-11-18 | 1998-11-18 | Sensor and circuit architecture for three axis strain gauge pointing device and force transducer |
Publications (1)
Publication Number | Publication Date |
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WO2000030027A1 true WO2000030027A1 (en) | 2000-05-25 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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PCT/US1999/027127 WO2000030027A1 (en) | 1998-11-18 | 1999-11-16 | Sensor and circuit architecture for three axis strain gauge pointing device and force transducer |
Country Status (7)
Country | Link |
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US (1) | US6243077B1 (en) |
EP (1) | EP1131781A1 (en) |
JP (1) | JP2002530755A (en) |
KR (1) | KR20020001708A (en) |
AU (1) | AU1478800A (en) |
CA (1) | CA2345413A1 (en) |
WO (1) | WO2000030027A1 (en) |
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US6411193B1 (en) | 2000-05-31 | 2002-06-25 | Darfon Electronics Corp. | Pointing stick with increased sensitivity |
CZ303035B6 (en) * | 2007-11-26 | 2012-03-07 | Ceské vysoké ucení technické v Praze, | Proportional sensors of shearing forces and contact pressure distribution |
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US6486871B1 (en) * | 1996-08-30 | 2002-11-26 | Semtech Corporation | Pointing device with Z-axis functionality and reduced component count |
JP2000259341A (en) * | 1999-03-12 | 2000-09-22 | Kooa T & T Kk | Pointing stick |
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- 1999-11-16 WO PCT/US1999/027127 patent/WO2000030027A1/en not_active Application Discontinuation
- 1999-11-16 KR KR1020017006103A patent/KR20020001708A/en not_active Application Discontinuation
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Also Published As
Publication number | Publication date |
---|---|
US6243077B1 (en) | 2001-06-05 |
AU1478800A (en) | 2000-06-05 |
KR20020001708A (en) | 2002-01-09 |
CA2345413A1 (en) | 2000-05-25 |
EP1131781A1 (en) | 2001-09-12 |
JP2002530755A (en) | 2002-09-17 |
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