JPS6334627A - Coordinate input device - Google Patents

Abstract

PURPOSE:To obtain a coordinate value with high accuracy, by obtaining the coordinate value based on the size of the voltage of the position of an input pen, at the time of setting an end part on one side of a resistance film as a high voltage side, and that of the voltage of the position of the input pen, at the time of setting the end part on the other side of the resistance film as the high voltage side. CONSTITUTION:The voltage is impressed setting the end part on one side of the resistance film 1 as the high voltage side. The size of the voltage of the contact position, or the approaching position of the input pen 9 at that time, is detected. Next, the voltage is impressed setting the end part on the other side of the resistance film 1 as the high voltage side, and the size of the voltage of the contact position, or the approaching position of the input pen 9 at that time, is detected. And the coordinate value is found based on detected two potential values. In other words, the sizes of these detected two potential voltages are related to a distance from the contact position, or the approaching position of the input pen 9 to the both ends of the resistance film 1. Therefore, the above stated distance, that is, the coordinate value can be obtained from the sizes of the two voltages.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a coordinate input device, and particularly relates to a coordinate input device using a resistive film and an input pen.

(Prior art) A coordinate input device using a resistive film applies AC voltages with different phases to both ends of the resistive film, detects the voltage generated in the resistive film with an input pen, and calculates the phase difference with a reference voltage. A phase difference detection method that determines coordinate values by comparison is disclosed in Japanese Patent Application Laid-Open No. 58-94068). When an AC signal is applied to a human-powered pen, the current flowing from the input pen into a resistor n is applied to the resistor. A current ratio detection system (Japanese Unexamined Patent Publication No. 56-97137) is known, in which coordinate values are printed based on the ratio of current flow to both ends of the membrane.

(Problem to be solved by the invention) However, in the above phase difference detection method, the phase difference and the coordinate values are not simply proportional, so in order to determine the coordinate values, complicated calculations or complicated analog circuits are required. In addition, the current ratio detection method requires two resistive films in order to obtain coordinate values in each of the mutually orthogonal directions (X direction and Y direction). The structure of the inlet panel becomes complicated, and a highly accurate resistive film is expensive, resulting in an increase in the cost of the entire device.

This invention solves the problems that exist in the phase difference detection method and the current ratio detection method described above, namely (a) complicated circuit device or calculation is required to determine position coordinates, (b) input cover panel part It eliminates the problem of a complicated structure, makes it possible to easily determine coordinate values based on the detection signal, and further simplifies the structure, making it possible to perform high-precision coordinate detection at low cost. The purpose is to provide an input device.

(Means for Solving the Problems) The coordinate input device of the present invention first applies a voltage to one end of the resistive film as a high voltage side, and then measures the magnitude of the voltage at the contact or approach position of the input pen. Then, apply a voltage to the other end of the resistive film as the high voltage side, detect the large difference in the voltage at the point where the input pen touches or approaches, and the values of the two potentials detected in this way. It calculates coordinate values based on .

[Effect]

The magnitudes of the two potential voltages detected as described above are related to the distance from the contact or approach position of the input pen to both ends of the resistive film. Therefore, the distance, that is, the coordinate value, can be determined from the difference in magnitude between the two voltages.

(Embodiment) FIG. 1 schematically shows the configuration of a coordinate input device of the present invention. In the coordinate input device of this embodiment, the input cover panel IP has a rectangular resistive film 1, and when the input pen 9 touches or approaches a point P on the resistive film 1, the position of the resistive film 1 at that point is This is to find the position of. The resistive film 1 has a uniform surface resistivity, and the input pen 9 is capacitively coupled to the resistive film 1 to transmit the voltage at point P to the amplifier circuit 10. amplifier 1
The distribution circuit 11 connected to the output side of the amplifier circuit 10
The output is divided into amplitude value detection circuits 12a to 12d. Each of the amplitude value detection circuits 128 to 12d receives input AC signals eX'l, eX2. eyl.

Amplitude value Ex of eV2 1. Ex 2. “y 1.gy
Outputs a signal representing 2. These signals are input to addition circuits 13a and 13bctj and division circuits 14a and 14b, and are used to obtain the X coordinate value and the X coordinate value as described later.

The position of point P on the resistive film 1 is expressed as a coordinate value with mutually perpendicular sides of the rectangular resistive film being the X direction and the y direction. In the illustrated example, the sides extending left and right on the drawing are 1X1, 1X
The direction of 2 is the X direction, and the vertically extending sides 1Y1, 1Y
The direction of 2 is the y direction.

The input panel part IP of this embodiment is located on the side 1 of the resistive film 1.
Three electrodes 2a to 2G, 2d to 2f, and 3a to 3C2 are provided along Y1, 1Y2, 1X1.1X2, respectively.
3d to 3f. Line 2y connecting electrodes 2a to 2C
The intersection point O of the line 3X connecting the electrodes 3a to 3C is the X coordinate, y
This is the origin of the coordinates.

Electrodes 2a-2C and 3a-3C are connected to conductor 6a via switches 4a-4G and 5a-5C, respectively. On the other hand, the electrodes 2d to 2f and 3d to 3f are
They are connected to the conductor 6b via switches 4d to 4f and 5d to 5f, respectively. The conductor 6a is connected to a high voltage side terminal 7a of an AC power source 7d or a ground potential terminal 7b via a changeover switch 7C. On the other hand, the conductor 6b is connected to the AC power source 8d via the changeover switch 8C.
It is connected to the high voltage side terminal 8a or the ground potential terminal 8b. AC power supplies 7d and 8d have the same voltage and frequency.

In addition, instead of providing two AC power sources 7d and 8d, as shown in FIG. 2, one AC power source (7d) is provided, and the switches 7c,
It is also possible to use components that interlock with each other as 8c and connect them as shown.

The switch control unit SC includes switches 4a to 4f.

5a to 5f', 7C and 8G as follows <a>
-・(d> is one operation cycle, and control is performed so that this cycle is repeated.

(a) In the first stage of operation, switches 48-4f
is closed, switches 58 to 5f are opened, and switch 7C is connected to high voltage side terminal 7a and switch 8G is connected to ground terminal 8b (state shown in FIG. 1).

(b) In the second stage of operation, switches 4a to 4f
is closed, the switches 58 to 5f are turned on (the above is the same as the first step), and the switch 7G is connected to the ground side terminal 7b, and the switch 8C is connected to the high voltage side terminal 8a.

(C) In the third stage of operation, switches 4a to 4f are opened, switches 58 to 5f are closed, and switch 7C is connected to high voltage side terminal 7d and switch 8C is connected to ground side terminal 8b.

(d> In the fourth stage of operation, switches 4a to 4f
, the switches 5a to 5f are closed (the above is the same as the third step), and the switch 7C is connected to the ground side terminal 7b and the switch 8C is connected to the high voltage side terminal 8a.

Among the above, the first stage and the second stage are performed at the point Pa'
) is necessary for determining the x-coordinate 11G, while the third and fourth stages are for determining the x-coordinate value of the point P. The principle of determining coordinate values will be explained below with reference to FIG. Here, we will take as an example the case where the X coordinate value is determined, but the same applies to the X coordinate value. FIGS. 3(a) and 3(b) show equivalent circuits of the resistive film 1, input pen 9, and amplifier 10 in the first and second stages described above.

R1 is the resistance from point P to electrodes 2a to 2C, while R2 is the resistance from point P to electrodes 2d to 2f. C represents the coupling capacitance formed between the input pen 9 and the resistive film 1. Further, R3 represents the input resistance of the voltage amplification circuit 10. R3 has a sufficiently large value compared to R'l and R2.

In the state of Fig. 3 (a>), the amplitude value E' of the voltage at point P is E' = E-R2/ (R1+R2>...(1) (However, E' is the amplitude value of the voltage at power supply 7d. Then, the amplitude value EX1 of the signal eX1 output from the amplifier circuit 10 is given by EX'1 = α・E′・R3/((1/ωC) +R]...
2) (10 shi, α is the amplification factor of the amplifier circuit 10, and ω is the angular frequency of the voltage.) Similarly, the amplitude value l3'' of the voltage at point P in FIG. 3(b) is E'' = E-R1/ (R1-+-R2>...(3)
The one-line width value EX2 of the signal ex2 output from the amplifier circuit 10 is given by
...(4) From equations (1) to (4), Ex 2/ (fEx 1 +Ex 2>=
R1/ (R1+R2>...(5) The distance from the electrode groups 2a to 2C to the point P (the distance from the line 2X connecting the electrodes 28 to 2C to the point P) is 11, and the electrode group 2d to
Distance from 2f to point P (line 2x connecting electrodes 2d to 2f
If the distance from ' to point P) is 12, the electrical resistance per unit length of the resistive film 1 is uniform, so R1/(R1+R2>=11/(11+12>...(6)) holds.Therefore, , (5), From equation (b), Ex 2/
(Lx 1+Ex 2> =11/(11+12)...(7)11+
Since 12 is constant, EX 1. If EX 2 is detected, 11, that is, the X coordinate value can be determined.

To achieve this, the distribution circuit 11 sends the output of the amplifier circuit 10, that is, exl, to the amplitude value detection circuit 12a in the first stage of operation, and sends the output of the amplifier circuit 10, that is, and ex2 from the second amplitude value detection circuit 12
send to b. These amplitude value detection circuits 12a and 12b are
Amplitude value EX1. of signal eX1°ex2. Detect EX2,
Outputs a signal indicating that value. The addition circuit 13a calculates the sum of both (Ex l+Ex 2>, and the division circuit 14a calculates the ratio Ex 2/(Ex 1+Ex 2>). The signal representing this ratio becomes the signal representing the X coordinate value.

The distribution circuit 11 sends the output ey1 of the amplifier circuit 11 to the amplitude value detection circuit 12c in the third stage of operation, and sends the output eV2 of the amplifier circuit 11 to the amplitude value detection circuit 12d in the fourth stage. Amplitude value detection circuits 12G and 12d find amplitude values EV1 and Ey2 of the input signals, respectively. The addition circuit 13b calculates the sum (Ey 1 +Ey 2>), and the division circuit 14b calculates the ratio EV 2/(EV 1 +EV). A signal representing this ratio becomes a signal representing the y-coordinate value.

As described above, the X coordinate value and the y coordinate value of point P are determined.

Note that the addition circuits 13a, 13b, and the division circuit 14a,
14b may be performed by a programmed microcomputer. In this case, the distribution circuit 11 is not provided, only one amplitude value detection circuit is provided, and its output is sampled at timings corresponding to the first to fourth stages, and A/D (analog/digital) converted. , respectively EX1. EX2. EV 1. It can be used as a signal representing EV2.

FIG. 4 shows an input panel part IP' that can be used in another embodiment of the present invention. In this inlet panel portion, the resistive film 40 consists of a rectangular high-resistance film portion 41 and a low-resistance film portion 42 formed in a band shape around the rectangular portion. The low resistance film portion 42 is a portion along each side, 42x1,4
It consists of 2x2°42'l/1,42y2. The low resistance film portions 42y1 and 42X1 are connected to the conductor 6a via switches 43a and 43b, 44a and 44b, respectively. On the other hand, the low resistance film portions 42M2, 42X2 are switches 431 and 43d, 44G and 44d, respectively.
It is connected to the conductor 6b via. Switch control part S
C is switches 43a to 43d, 44a to 44dk
: On the other hand, the same control as that for the switches 4a to 4f and 5a to 5f in FIG. 1 is performed. That is, in the description of the embodiment of FIG.
8 to 43d" and "switches 5a to 5f" to "switches 44a to 44dl", the explanation applies directly to the embodiment shown in FIG. 4.

When determining the X coordinate value (that is, in the first and second steps described in the embodiment of FIG. 1), the low resistance film portion 4
2y1, 42V\2 serves as an electrode for applying an alternating voltage between both ends of the high resistance film 41.

At this time, the low resistance film portions 42x'l and 42x2 act as resistors. On the other hand, when calculating the y-coordinate value, the low resistance film portion 4
2X1, 42X2 works as an electric current, and the low resistance film part 42
1/1.42'l/2 acts as a resistor and has a low resistance film portion 4
2y1 and 42V2 act as resistors. The lower the resistivity of the low-resistance film 42, the better it is as an electrode, but on the other hand, when used as a resistor, the bypass effect with respect to the high-resistance film increases. Therefore, the low resistance film 4
The resistivity of No. 2 needs to be appropriately determined in relation to the resistivity and dimensions of the high-resistance film 41. -For example, high resistance film is A
If the width of the low resistance film is approximately 1 cm, the surface resistivity of the high resistance film is set to 2.5 to 4 Ω/mm, and the surface resistivity of the low resistance film is set to 0. .6 to 1Ω/mouth.

The circuits connected to the input pen 9 and its output side are the same as those shown in FIG. 1 (10 to 14a).

14b) can be used, and the operation of the circuit for detecting coordinate values is also the same as in the case of FIG.

The coordinate values obtained in this way are the left side (
(Fig. 4) is bound to Y@, the base (Fig. 4) is taken as the X axis, and the position on the X and y coordinates with the intersection point as the origin is expressed.

In each of the above examples, the (film width value) of the voltage at point P was detected and the coordinate values were determined based on this, but if the effective value, average value, etc. It can be anything.

[Effects of the Invention] As described above, according to the present invention, the magnitude of the voltage at the position of the input pen when one end of the resistive film is set to the high voltage side and the input when the other end is set to the high voltage side Since the coordinate values are determined based on the magnitude of the voltage at the position of the pen, the coordinate values can be determined with high accuracy with a simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing an embodiment of the coordinate input device of the present invention, FIG. 2 is a circuit diagram showing a partial modification of the coordinate input device of FIG. 1, and FIG. (b) is an equivalent circuit diagram showing the electrical states of the resistive film, input pen, and amplifier circuit of the coordinate input device of FIG. 1 at each stage of operation, and FIG. 4 is a coordinate input device of another embodiment of the present invention. FIG. 2 is a schematic diagram showing an input panel part of the device. 1... Resistive film, 4a to 4f, 5a to 5f... Switch, 7G, 3c... Changeover switch, 7d, Qd...
AC power supply, 9... input pen, 10... amplifier circuit, 1
DESCRIPTION OF SYMBOLS 1... Distribution circuit, 12a-12d... Amplitude value detection circuit, 13a, 13b-... Addition circuit, 14a, 14b...
...Division circuit, 41...High resistance film, 42...High resistance film, 43a to 43d, 44a to 44d...Switch.

Claims (1)

[Scope of Claims] A resistive film; an AC voltage applying means for applying an alternating voltage between both ends of the resistive film; In a coordinate input device comprising an input pen that detects the potential of a point, and a detection circuit that detects the coordinate value of the point based on the detected voltage, the voltage applying means is configured to connect one end of the resistive film. applying a voltage with one end on the high voltage side and the other end on the low voltage side, and then applying a voltage with the other end on the high voltage side and the one end on the low voltage side; The coordinate value of the point is based on the magnitude of the voltage at the point when the end of is on the high voltage side and the magnitude of the voltage at the point when the other end is on the high voltage side. A coordinate input device characterized by determining.