JPS59127181A - Coordinate input device - Google Patents

Abstract

PURPOSE:To ensure an accurate input of coordinates even with a touch of hands by providing in division a conductive film on a single side of a pressure-sensitive sheet together with a resistance film provided on the other side of said sheet respectively. CONSTITUTION:A conductive film is divided into parts 3a-3d and set, and a control means 16 closes successivly the switches 14a-14d, one by one. When the switch 14c is closed, the film 3c operates. Thus the coordinates on the film 3c can be read. A wide region is divided into some parts, and the coordinates are read every divided region. Thus the coordinates can be fed accurately by means of a pen even in case where the input of coordinates is carried out with the pressure given to a certain region of the film 3d with the pen while having a contact between the hands and a certain region of the film 3a. In such a way, various deformations are possible in response to a presumed touch of hands to a region.

Description

Detailed Description of the Invention [Technical Field of the Invention] This invention uses a pressure-sensitive sheet to obtain a signal corresponding to the position of the pressure-sensitive sheet to which pressure is applied, and based on this signal, This invention relates to an improvement of a coordinate input device for inputting the above coordinate values.

[Technical background of the invention and its problems]

A conventional device of this type will be explained with reference to FIG. In the figure, 1 indicates a tablet. This tablet 1 is enlarged, and a conductive film 3 is placed on one side of a pressure-sensitive sheet 2 made of a pressure-sensitive resistor.
is formed in the shape of a metal sheet by vapor deposition, sputtering, etc., and a uniform resistive film 4 is formed on the other side of the pressure sensitive sheet 2 by vapor deposition, sputtering, etc., to form a laminated structure. Tablet 1 is a flow collection example with
A laminated structure of metal sheets, pressure-sensitive sheets, and resistance plates may also be used.

On each of the four sides of the resistive film 4, for example, three backflow prevention diodes 5a to 5d are provided with anodes connected to the resistive film 4. The cathode of the diode 5a is connected to the switch 7a via a resistor 6&, and the cathode of the diode 5b is connected to the switch 7a via a resistor 6b. Also, the cathode of the diode 5c is a resistor 6d.
The cathode of the diode 5d is connected to the switch 7b via a resistor 6c.

The switch 7a, 7bti is grounded via the resistor 8, and the voltage at the connection point between the resistor 8 and the switch 7a e 7b is configured to be input to the inverting input terminal of the operational amplifier IO. Further, a voltage source 9 for applying a reference voltage is connected to a non-inverting input terminal of the operational amplifier 10. The output terminal of this operational amplifier 10 is connected to the conductive film 3,
The output terminal of the operational amplifier 10, the conductive film 3, the short circuit point which is the suppression position of the pressure sensitive sheet 2, the resistive film 4, and the diodes 5a to 5.
d, resistors 6a to 6d, switch 'ya+7bb, resistor 8, and operational amplifier 100 input terminal form a constant current circuit.

Furthermore, the input terminal of an operational amplifier 11a is connected to both ends of the resistor 6a, and the sampling hold circuit 12a is connected to the output terminal of the operational amplifier 11m.

Further, the input terminal of the operational amplifier 11b is connected to both ends of the resistor 6C, and the sampling hold circuit 12b is connected to the output terminal of the operational amplifier 11b.

In the coordinate input device configured as described above, switch 7
The conceptual diagram when & is closed is like the person in Figure 2. When the conductive film 3 is pressed with the pick or pen 13, the pressure-sensitive sheet 2 is also pressed, and the suppressed position on the conductive film 3 and the position of the resistive film 4 directly below it are separated through the pressure-sensitive sheet 2. Short circuited. This state is shown in an equivalent circuit as shown in FIG. 2B. That is, the current (11+i2) flows out from the constant current source 10', and the resistance 2' corresponding to the pressure sensitive sheet 2 becomes almost zero due to the pressure, so the current (1, +i, ) flows out from the resistance corresponding to the resistive film 4. 4', the current 11 flows to the switch 7a via the diode 5a and the resistor 61, and the current 1. flows to switch 3-7a via diode 5b and resistor 6b. Current 1 and current 12 mean pen 13
It is determined by the resistance ratio of the resistive film 4 corresponding to the pressed position of the conductive film 3. Therefore, the coordinates can be determined based on this current. Therefore, the current 11 is
The operational amplifier 11a detects the voltage across the resistor 6a caused by the current flowing into the signal, and this signal is held in the sampling and hold circuit 12&.

The above has described the signals corresponding to the coordinates in the vertical direction (Y direction) in FIG. 1, but when the switch 7b is closed instead of the switch 7a, A signal corresponding to the coordinate value in the (X direction) is held in the sampling hold circuit 12b via the operational amplifier iib.

As shown in FIG. 3, the pressure-sensitive sheet 2 of the tablet 1 used in the coordinate input device described above is made of a base material 21 made of silicone rubber with particles of a good conductor such as metal or carbon as a filler n. It is mixed. In this case, the spacing between the fillers should be set at an appropriate distance, and when the pressure-sensitive sheet 2 is not suppressed, it will act as an insulator so that when the pressure-sensitive sheet 2 is pressed with a thin object such as a pen tip, the K allows it to work as a conductor even under low pressure.

Further, when pressing the pressure-sensitive sheet 2 with a relatively large area such as a fingertip, a certain amount of pressure is required.

However, it is extremely difficult to uniformly distribute the filler 4 within the base material 21. For this reason, generally, the filler 4 within the pressure sensitive sheet 2 is unevenly distributed.
In a portion where the filler n has a high density, that portion becomes a conductor even when pressed with a relatively small external pressure.

As a result, as shown in FIG. 4, the paper on the conductive film 3 was pressed down with the fingertips of the left hand! (21 points), or the tip or joint of the little finger of the right hand holding the pen 13 touches the paper (21 points).
Point 2) Then, if the density of filler B is high in that part as described above, the pressure sensitive sheet 2 becomes a conductor also at points 21 and 22. Therefore, the constant current flowing out from the operational amplifier 10 shown in FIG. A phenomenon called ``shitezuke'' has occurred. According to this phenomenon, the operational amplifier 11a,
The voltage detected by llb does not correspond to the position pressed by the pen 13, resulting in an erroneous input.

[Purpose of the invention]

The present invention has been devised in view of the drawbacks of the conventional example described above, and its purpose is to provide a coordinate input device that does not cause erroneous input even when using the newly developed ``hand''.

[Summary of the invention]

Therefore, in the present invention, a conductive film is separately arranged on a pressure-sensitive sheet, and a signal corresponding to the position on the pressure-sensitive sheet where pressure is applied is held from the resistive film through the pressure-sensitive sheet and the conductive film. The control means sequentially scans the divided conductive films and determines whether coordinate input is required based on at least the number of positions where pressure is applied.

[Embodiments of the invention]

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 5 is a block diagram of an embodiment of the present invention, in which the same members as in FIG. 1 are given the same numbers and their explanations will be omitted.

The fifth conductive film is divided into strip-shaped conductive films 3a+3b and 3c+3d, each having a length of about 5 m to 10<->, for example. Each conductive film 3a+3b+3c.

A lead wire is pulled out from 3d and switches 14&.

14b, 14c, and 14d, respectively. These switches 14a, 14b, 14c, 1
4d are both connected to the output terminal of the operational amplifier 10.

Sampling and holding circuits 15a and 15b are connected after sampling and holding circuits 12a and 12b, respectively. And operational amplifier 11a + llb, sampling hold circuits 12a, 12b, 15a
, 15b constitutes a holding means.

16 is a control means. This control means 16, for example,
Consists of a microprocessor and memory, signal line 1
6a to control the opening and closing of the switches 14a to 14d,
The opening/closing of the switch 7g+7b is controlled via the signal line 16b, and the sampling and hold circuits 12a, 12b, 15a are controlled via the signal lines 16c, 16d.
, 15b performs switching control between springing and holding.

Furthermore, the presence or absence of signals in the sampling and holding circuits 12a and 12b is taken in from the signal line 16c. Furthermore,
The control means 16 performs processing according to the flowchart in FIG. ``First, the control means 16 turns on one of the switches 14a to 14d (initially 14a) in the step ``turning on the switch 141.'' Here, the control means 16 turns on one of the switches 14a to 14d (initially 14a). The presence or absence of “X%Y” is received via the signal line 16c,
Execute the step "i" with coordinate data present. That is, the switch 7a is closed via the signal line 16b to detect the X coordinate data, and the switch 7b is closed to detect the X coordinate data. , if YES, the control means 1
Step 6 proceeds to the step of "data flag=17". That is, the control means 16 reads the "number of signal detections" written in the flag area of its own memory, and determines whether the number of times is 1 or not. If the result is NO, the control means 16 sets the sampling hold circuit 12a to the hold mode in the step of "Write S/H circuit 12alb". Then, in the step "Data Flag=1#", the contents of the flag area of the memory mentioned above are rewritten to 1.

Following this, or if NO is obtained in the step of "X%Y coordinate data present ↑" mentioned above, check whether the Stella 6 of "i-d?" and the closed switch was 14d. If NO, change the order of closing the switches to a-4b-+C
Turn on the rotation in the order of -4d, and then switch 'switch 1 again.
Return to step 41 “Insertion”.

That is, the conductive films 3a to 3d are sequentially scanned.

When the branch is made to YES in the step "i-d?", the control means 16 asks 'Data flag=1?' ”, read the “number of signal detections” written in the flag area of the memory, determine whether the number of times is 1, and
If it is ES, the sampling hold circuit 15a is set to the hold mode in the "S/H circuit 15a+b writing" step.

As a result of sequentially scanning the conductive films 3a to 3d, a signal was detected only for one conductive film.
This allowed the signal to be held.

Now, following this, or "X1Y coordinate data available ↑"
K! ! <If YES in the step “Data flag - 1?” or NO in the step “Data flag = 1?” following “i=d?” Ill, a
In the step ``, preparations are made to close the switch 14a, and then in the step %' data flag=0'', the data in the flag area in the memory is cleared. Then, the process is repeated again from the step of "turning on the switch 141". In this embodiment, even if there is a valid input, the next sequential scan is performed from the switch 14a, but the next input point following the valid input point corresponds to the valid input point. Since there is a % difference on the conductive film other than on the conductive film or on the conductive film adjacent to the conductive film, taking this into consideration, the next sequential scan is performed on the three conductive films before and after including the conductive film corresponding to the valid input point. You can also do as you like. In this way, the detection speed can be increased.

In the coordinate input device as described above, for example, as shown in FIG.
, 3d, one of the “
Data flag = 1? ” In the step “i=
A”, and the flowchart in Figure 6 can be repeated, so as long as there is some effort, all inputs will be invalidated, and the correct input point (one manual point for four conductive films) will be determined. It is valid only when

In the above explanation, the conductive film is in the form of a strip.
As shown in the figure, an area to be "touched" may be assumed, and the area may be divided into corresponding areas. of course,
The width of the strip may be narrowed to enable accurate input. Furthermore, even if the conductor is not uniform within one region of the conductive film,
A mesh-like structure or a structure in which slits or the like are arranged at suitable vortices may be used as long as the resolution is not degraded.

11-Also, in the embodiment, a signal corresponding to the position was obtained by dividing current using a constant current, but for example, as shown in FIG. 9A, with the voltage source 9,
Diode 5! Between L l S b (5c.

5d) at a constant voltage, and use the pen 13 to
When the pressure sensitive sheet 2 is pressed, the voltage generated on the conductive film 3 is
The voltage detector 17 may also be used for detection.

In other words, as shown in the equivalent circuit of FIG. 9B, a potential distribution from Ov to 'vOVK is created between the diodes 5a and 5b at the resistor 4' corresponding to the resistive film 4, so that the point pressed with the pen 13 A corresponding voltage is derived to voltage detector 17. Based on this voltage, coordinate values are calculated.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to input coordinates accurately, even though there is no erroneous input due to ``manipulation''.

Furthermore, since there is no need to consider the quality of the pressure-sensitive sheet as in the past, the time required for testing the pressure-sensitive sheet can be reduced, leading to a reduction in man-hours and costs.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the conventional example, Fig. 2 is a conceptual diagram for explaining the operation of Fig. 12-, Fig. 3 is a conceptual diagram for explaining the characteristics of the pressure-sensitive sheet, and Fig. 4 is a conceptual diagram for explaining the operation of the pressure-sensitive sheet. So-called "hands on"
FIG. 5 is a block diagram of the present invention, FIG. 6 is a flow chart for explaining the present invention, FIG. 7 is a plan view of a tablet for explaining the present invention in detail, and FIG. FIG. 8 is a plan view of a tablet in which the direction of the conductive film is changed, and FIG. 9 is a conceptual diagram of another embodiment of the present invention. 2...Pressure sensitive sheet 3.3a+3b+3ct3d"・Conductive film 4...Resistive film (lla, llb, 12a, 12b,
15a, 15b) = holding means 16...control means

Claims (3)

[Claims] (1) A pressure-sensitive sheet made of a pressure-sensitive resistor whose resistance value changes depending on the applied pressure, a conductive film divided and arranged on one side of this pressure-sensitive sheet, and the other side of the pressure-sensitive sheet. a resistive film disposed therein, and a holding means for capturing and holding a signal corresponding to a position on the pressure sensitive sheet from above the resistive film through the pressure sensitive sheet and the conductive film. ,
A coordinate input device comprising: a control means that sequentially scans the divided conductive film and determines whether coordinate input is valid or invalid based on at least the number of positions to which pressure is applied. (2) The coordinate input device according to claim 1, wherein the conductive film and the resistive film are disposed on the pressure-sensitive sheet by vapor deposition or sputtering. (3) The control means treats all the signals as invalid when signals are taken in from the plurality of conductive films to the holding means as a result of sequential scanning.
The coordinate input device according to item 1 or 2.