JPS6339019A - Pressure-sensitive coordinate input device - Google Patents

Abstract

PURPOSE:To ensure simultaneous detection of two coordinate positions by providing the 1st and 2nd pressure-sensitive rubber sheets at both sides of an electrode sheet and then the 1st and 2nd coordinate driving electrode group sheets at the outside of each rubber sheet. CONSTITUTION:The 1st driving electrode group sheet 11 contains a thin wire conductor 11a printed in the direction (x) and a belt-shaped resistor 11b applied in the direction (y). The resistor 11b is chiefly made of carbon and crosses an end of the conductor 11a. The sheet 11 is provided on an insulated substrate 10 and the conductor 11a has a contact with a pressure-sensitive rubber sheet 12. An electrode sheet 13 is put on the sheet 12 and a pressed area of the sheet 12 conducts. The 2nd pressure-sensitive rubber sheet 14 and the 2nd driving electrode group sheet 15 are provided on the sheet 13. The sheet 15 has the different coordinates from the sheet 11. Therefore it is possible to obtain simultaneously the potentials corresponding to both coordinate positions when the pressure is applied.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a pressure-sensitive coordinate human-powered device that detects a position pressurized by a writing instrument and digitizes and outputs a voltage corresponding to the detected position. .

(Prior art) Devices for inputting characters and figures into electronic computers, such as
In the F-character human-powered device, a pressure-sensitive coordinate input device has conventionally been used as a device for detecting the coordinates of the pen position.

The basic configuration of a conventional pressure-sensitive Jv) coordinate human-powered device is shown in FIG. 2 (for example, Japanese Patent Laid-Open No. 58-24977). In the figure, a high resistance film 2 is coated on an insulating substrate l, and the surrounding area 4
A low resistance film 3 having a sufficiently smaller resistance value than the high resistance film 2 is applied to the sides, a pressure sensitive rubber 4 is provided on the resistance films 2 and 3, and an electrode sheet 5 is placed on top of the pressure sensitive rubber 4. A shield sheet 6 is provided. Note that the high resistance M2 is specifically one in which fine carbon particles are kneaded and applied to a binder resin. Furthermore, the low resistance film 3 is coated with silver as the main material. Specifically, the pressure-sensitive rubber 4 is made by embedding metal particles in silicone rubber, and uses anisotropic pressure-sensitive conductive rubber in which the metal particles conduct only in the vertical direction at a certain pressure or higher when pressurized. ing. Further, the electrode sheet 5 and the shield sheet 6 are made of flexible material.

The operation is performed in the x and X directions in a time-division manner, and when determining the X coordinate, a voltage is applied in the X direction. When applying voltage in the X direction, apply voltage E [V] to points B and C, and apply 0 to points A and D.
When [V] is applied, the entire low resistance 11Q3-BC takes a value near E [V], and the low resistance 11!23-A
The entire D takes a value near 0 [V]. In addition, low resistance Il
! 23-AB and low resistance film 3-DC are O[V] to E
The high resistance film 2, which has a potential gradient to [V] and is driven by the low resistance film 3-BC and AD, also has a potential gradient from O[V] to E[
V], by making the resistance distribution inside each resistor 2.3 uniform regardless of the size of the resistive film, the potential gradients of both resistors become almost equal, and there is little disturbance in potential. becomes.

Next, when finding the Y coordinate, apply a voltage in the X direction,
Voltage E [V] is applied to points A and B, and voltage 0 [V] is applied to points C and D.
] is applied to form a potential gradient in the X direction in the same manner as when determining the Xi mark.

When a voltage is applied alternately in the X direction and the
It is transmitted to the electrode sheet 5 as a conductor film through the conductive film.

This potential is A/D converted in synchronization with the timing of drive voltages applied alternately in the x and x directions, and as a result, the x and y coordinate values on the tablet are obtained.

(Problems to be Solved by the Invention) However, the above-described conventional pressure-sensitive coordinate human-powered device has the following problems.

(a) Since a time division method is used to detect voltages corresponding to the X and Y coordinate positions, the X and Y coordinates cannot be obtained simultaneously. Furthermore, there is a problem in that the time-division sampling period is limited due to the circuit characteristics of the tablet structure. Hereinafter, this problem will be explained in detail.

FIG. 3 shows an equivalent circuit of the device shown in FIG.

In the figure, SW indicates an operating part that applies voltage in the x and X directions in a time-division manner, N indicates a noise source, and UPI and OP2 indicate an impedance converter. In FIG. 3, when the SW is closed while pressing an arbitrary point on the tablet, the corresponding point '' and '' on the resistor R1 are guided to the electrode sheet 5 via the resistor R2, and the impedance converter OPI via A/
It is manually transferred to the D conversion section. At this time, a distributed capacitance C1 between the electrode sheet 5 and the ground, which depends on the pressure-sensitive characteristics of the pressure-sensitive rubber 4, is
, there is a time delay from when the SW is closed until the voltage of the electrode sheet 5 becomes stable. When the SW is closed, if the combined resistance of the resistors R1 and R2 for charging the distributed capacitance C1 is equivalently R, the voltage waveforms guided to the electrode sheet 5 are as shown by ■ to ■ in Fig. 4. Change exponentially. In this case, the time constant is =R-CI. The resistance value R changes depending on the degree of suppression of the pressure-sensitive rubber 4, and as the pressure decreases, R becomes large, and the time constant also increases, so the voltage waveform changes as shown in ■ and ■ as the suppression decreases. . The X and Y coordinates must be obtained by sampling the value 1 when the voltage introduced to the electrode sheet 5 is in a steady state.

Therefore, in the time division method, the sampling period for detecting the voltage corresponding to the X and Y coordinate positions must be determined in consideration of the time delay until the voltage of the electrode sheet 5 becomes stable.

(b) High resistance 1 and 2, which are one element that determines the absolute degree of voltage that supports the X and Y coordinate positions, apply pressing force through the shield sheet 6, electrode sheet 5, and pressure sensitive rubber 4 when writing. receive. In this case, when the writing instrument sweeps while being pressed, a frictional force is generated between the high-resistance film 2 and the pressure-sensitive rubber 4. Due to this frictional force, among the metal particles contained in the pressure sensitive rubber 4, the high resistance parts 1 and 2 are scraped by the metal particles exposed on the rubber surface. As a result, there is a problem in that the absolute volume deteriorates and the life span is significantly shortened.

(C) The absolute particle size depends on the uniformity of the resistance value distribution of high resistance +15!2 and low resistance 15!3. Therefore, it is necessary to manufacture these resistive films with high precision and uniform resistance value distribution. As a method for this purpose, a method of controlling the resistance film coating conditions must be applied to the high resistance film 2, and a method of trimming must be applied to the low resistance film 3. This trimming method involves, for example, providing check terminal patterns at regular intervals of 10 to 20 mm in the longitudinal direction of Low Resistance@3, and trimming the resistive film so that the resistance between these terminals becomes the specified resistance value. It is something to be adjusted. In this way, manufacturing a resistive film must be carried out under strict control conditions, and the resistance value distribution must be adjusted through complicated trimming, which leads to the problem of extremely low manufacturing efficiency. There is a point.

Furthermore, since two resistive films are formed on one substrate, if one of the resistive films is out of specification, the device itself becomes unusable, resulting in a low yield.

Therefore, it is an object of the present invention to solve the problems mentioned in -F.

(Means for Solving the Problems) The present invention provides a first drive electrode group having an insulating substrate, a plurality of arranged thin wire conductors, and a strip resistor crossing one end of the plurality of thin wire conductors on the upper surface. a first pressure-sensitive rubber sheet provided on the sheet, a first pressure-sensitive rubber sheet provided on the first drive electrode group sheet, and a conductor film provided on the first pressure-sensitive rubber sheet and mutually insulated on the upper surface and the F surface. an electrode sheet, a second pressure-sensitive rubber sheet provided on the electrode sheet, and a plurality of thin wire conductors provided on the second pressure-sensitive rubber sheet and spaced apart in a direction orthogonal to the predetermined direction. The device includes a second drive electrode group sheet having a band-shaped resistor on its lower surface that crosses one end of a plurality of thin wire conductors, and a protection sheet provided on the second drive electrode group sheet.

Then, a potential difference is applied to both ends of each strip-shaped resistor of the first and second drive electrode group sheets, and potentials corresponding to the respective coordinates are obtained from the conductor films of the electrode sheets.

(Function) When the protective sheet is pressed with a writing instrument, the first pressure-sensitive rubber sheet is electrically connected in the upper direction at the pressing point, and the thin wire conductor of the first driving electrode group sheet at the pressing point and the lower surface of the electrode sheet conductor film provided on the conductive film. Therefore, the potential of the strip resistor of the first drive electrode group sheet to which the thin wire conductor at the pressing point is connected is provided on the lower surface of the electrode sheet via the thin wire conductor and the first pressure-sensitive rubber sheet. It is transmitted to the conductive film that is Therefore, a potential corresponding to one coordinate of the pressing point can be obtained from this conductor JIQ.

Simultaneously with this operation, a potential corresponding to the other coordinate of the pressing point is obtained from the conductor film provided on the upper surface of the electrode sheet in the same manner as the above operation.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of the present invention. In the figure, a drive electrode group sheet II is provided on an insulating substrate L-H. This drive electrode group sheet II is made by printing thin wire conductors 11a made of silver paste at a pitch of about 3 mm on a flexible polyester film in the X direction, and carbon fibers crossing one end of these thin wire conductors 11a. Band-shaped resistors 11bF, 2y mainly made of
It is applied in the direction. This drive electrode group sheet 11
is the insulating substrate+(
11. A sheet-like pressure-sensitive rubber 12 is provided on the drive electrode group sheet TI. The pressure-sensitive rubber 12 is, for example, silicone rubber with metal particles embedded therein, and is an anisotropic pressure-sensitive conductive rubber in which the metal particles conduct only in the upper direction when pressurized at a certain pressure or higher. An electrode sheet 13 is provided on this pressure sensitive rubber 12F.

The electrode sheet 13 is, for example, a flexible insulating film provided with conductor films (formed of silver, for example) that are insulated from each other on the upper surface and the F surface. This electrode sheet 13
A sheet-like pressure sensitive rubber 14 is provided on the top.

Pressure sensitive rubber 14 is formed similarly to pressure sensitive rubber 12. A drive electrode group sheet 15 is provided on the pressure sensitive rubber 14 . This driving electrode group sheet 15 is made by printing thin wire conductors 15a made of silver paste in the X direction at a pitch of about 3 mm on a flexible polyester film, for example.
A band-shaped resistor +5b made mainly of carbon is applied in the X direction across one end of these thin wire conductors 15a. The drive electrode group sheet I5 is provided so that the thin wire conductor 15b faces downward, that is, in contact with the pressure sensitive rubber 14. A protective S sheet +6 is provided on the drive electrode group sheet 15. The protective sheet 16 is a film made of, for example, urethane, vinyl chloride, polyester, etc.
The thickness is selected taking into account writing comfort, durability, pressure sensitivity, etc. Preferably, the thickness is about 100 to 250 μm.

Next, the operation of this embodiment will be explained.

First, drive electrode group sheet 1! One end of the strip resistor 11b has a potential of 0 [V], and the other end C has a potential of E [V]
shall be. That is, 0[V] is applied to the strip resistor 11b in the X direction.
] to E [V]. On the other hand, the end portion B of the strip resistor 15b of the drive electrode group sheet 15 is placed at a potential of 0.
[V], and the other end A is set to a potential E [V].

That is, the strip resistor 15b is made to have a potential gradient from 0 [V] to E [V] in the X direction.

In such a state, when a writing instrument such as a ballpoint pen is pressed from above the paper placed on the protective sheet 16, the pressure-sensitive rubber 14 becomes conductive in the vertical direction at the pressing point, and the thin line of the drive electrode group sheet 15 at the pressing point Conductor 15a and electrode sheet 13
The conductor film provided on the top surface of the is electrically conductive. Therefore,
The potential of the strip resistor 15b at the point where the thin wire conductor 15a is connected at the pressing point is transmitted to the conductor film provided on the upper surface of the electrode sheet 13 via the thin wire conductor 15a and the pressure sensitive rubber I4. Therefore, a potential corresponding to the X coordinate of the pressing point can be obtained from this conductive film.

On the other hand, a potential corresponding to the Y coordinate of the pressing point is also obtained at the same time. That is, the pressure-sensitive rubber 12 is electrically connected in the vertical direction at the pressing point, and the thin wire conductor 11a of the drive electrode group sheet 11 at the pressing point
and the conductor film provided on the lower surface of the electrode sheet 13 are electrically connected. Therefore, the potential of the strip resistor 11b at the point where the thin wire conductor 11a is connected at the pressing point is transmitted to the conductor film provided on the lower surface of the electrode sheet 13 via the thin wire conductor 11a and the pressure sensitive rubber 12. . Therefore, a potential corresponding to the Y coordinate of the pressing point can be obtained from this conductive film.

(Effects of the Invention) As explained above, according to the present invention, the following effects F can be obtained.

(a) Since the present invention has a structure in which the members for detecting the X and Y coordinates are electrically insulated and separated, the X and Y coordinates of the pressed point can be obtained at the same time. Therefore,
It is much faster than detection using the conventional time division method.

(b) Members corresponding to the high resistance film 2 and low resistance film 3 of the conventional device are two drive electrode group sheets in the present invention. These drive electrode group sheets are comprised of sheets provided with the thin wire conductors and strip-shaped resistors provided as described above. Therefore, no pressing force is applied to the strip resistor itself which determines the absolute granularity of coordinate detection. Therefore, it is possible to avoid deterioration in the absolute accuracy of the resistor and damage caused by pressing, and to extend the life of the resistor. In the present invention, the pressing force is applied to the thin wire conductor, but even if the thin wire conductor is scraped due to the frictional force with the pressure-sensitive rubber as described above, it is unlikely to be cut. Therefore, is the thin wire conductor conductive? Absolute accuracy is not affected as long as the accuracy is maintained.

(C) In the conventional device, one resistor was provided on the entire surface of the writing surface, but in the present invention, by using a band-shaped resistor provided at the end of the writing surface, the area of the resistor is significantly reduced compared to the conventional device. can do. Furthermore, since the conventional low resistance film is removed, the resistance value distribution and coating film thickness of only the strip resistor can be controlled and adjusted by trimming. Therefore, it is easier to manage and adjust absolute accuracy than in the past.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an embodiment of the present invention, FIG. 2 is a diagram showing an example of a conventional pressure-sensitive coordinate human-powered device, FIG. 3 is a diagram showing an equivalent circuit of the conventional device, and FIG. 4 is a diagram of the conventional FIG. 3 is a diagram showing the electrical characteristics of the device. IO... Insulating substrate ++, +5... Drive electrode group sheet 11a, 15a---Thin wire conductor 11b, 15b---Strip resistor 12.14...Pressure sensitive rubber 16...Protection sheet.

Claims (1)

[Scope of Claims] An insulating substrate; a first resistor provided on the insulating substrate and having on its upper surface a plurality of thin wire conductors arranged at intervals in a predetermined direction and a strip resistor crossing one end of the plurality of thin wire conductors; A drive electrode group sheet, a first pressure sensitive rubber sheet provided on the first drive electrode group sheet, and a conductor film provided on the first pressure sensitive rubber sheet and mutually insulated on the upper and lower surfaces. a second pressure-sensitive rubber sheet provided on the electrode sheet; and a plurality of thin wire conductors provided on the second pressure-sensitive rubber sheet and spaced apart in a direction orthogonal to the predetermined direction. and a second drive electrode group sheet having on its lower surface a band-shaped resistor that crosses one end of the plurality of thin wire conductors; and a protection sheet provided on the second drive electrode group sheet; A pressure-sensitive coordinate input device characterized in that a potential difference is applied to both ends of each band-shaped resistor of two drive electrode group sheets, and a potential corresponding to each coordinate is obtained from a conductor film of the electrode sheet.