JPS63123115A - Coordinate position detecting method - Google Patents

Abstract

PURPOSE:To obtain a highly accurate coordinate input device by specifying either of auxiliary electrodes to sandwich a depressed point, operating a depressed point position from the voltage of the specified auxiliary electrode and the voltage of the pressure point and detecting the coordinate position of the pressure point. CONSTITUTION:Plural linear auxiliary electrodes 13 and 14 parallel to respective collecting electrodes 5a, 5b, 8a and 8b are formed at an equal interval, for example, the good electric conductor such as a silver paste on resistance films 4 and 7 of respective resistance sheets 1 and 2. Thus, since plural auxiliary electrodes 13 and 14 are formed, an equipotential line is formed on the resistance films 4 and 7 by these auxiliary electrodes, and at the narrow section between the auxiliary electrodes, the distortion of the equipotential line due to the resistance film thickness difference and the presence of a scratch is compensated by the auxiliary electrode at both sides and comes to be very small. The operation is executed by the voltage measuring value due to the comparatively short resistance part between the auxiliary electrodes 13 and 14 and the voltage value of the auxiliary electrode. Thus, the highly accurate coordinate position detection can be rapidly executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a coordinate position detection method for a coordinate input device.

[Conventional technology]

2. Description of the Related Art Coordinate input devices have been proposed in which input is performed by pressing resistive films of resistive sheets that face each other in close proximity.

For example, FIGS. 9 and 10 show basic examples of conventional coordinate input devices that detect input coordinates using voltage. 1 is a lower resistance sheet, 2 is an upper resistance sheet, and the lower resistance sheet 1 is A thin resistive film 4 made of indium oxide or the like is deposited on the top surface of an insulating substrate 3 made of polyester film or the like by vapor deposition or the like, and current collecting electrodes 5a are arranged at both ends of the resistive film 4 parallel to the Y direction.
, 5b are deposited. Further, the upper resistive sheet 2 has a resistive film 7 similar to that described above on the lower surface of a flexible insulating substrate 6 such as a polyester film, and current collecting electrodes 8a extending in the X direction orthogonal to the Y direction at both ends of the resistive film 7.

8b is deposited and formed. Each of these resistance sheets 1.
2 are arranged close to each other in parallel, with the respective resistive films 4.7 facing each other, with an insulating spacer 9 in the form of a frame or dots being interposed between them. Then, one current collecting electrode 5a of each resistor sheet 1.2
, 8a are connected to a DC power supply 11 via a switching circuit 10, and each of the other current collecting electrodes 5b, 8b is grounded via another switching circuit 12. Each switching circuit 10.12 is controlled by a computer, for example, to apply a constant DC voltage to each current collecting electrode 5a of each resistor sheet 1, 2.

5b and 8a, 8b alternately.

Now apply a DC voltage to the lower resistor sheet 1, open the upper resistor sheet 2, and open the upper resistor sheet 2.
Pressure is applied to an arbitrary point p from above with a stylus, a finger, etc., and the resistive film 4°7 of each resistive sheet 1.2 is brought into point contact with the point p. Then, a potential distribution occurs in the resistor M4 of the lower resistor sheet 1 in the X direction, and a divided voltage eX is generated at a point p on the resistor film 4 as shown in FIG. It is detected from the current collecting electrode 8a of the resistance sheet 2. Here point p
With the coordinates of (x, y), both current collecting electrodes 5 of the lower resistive sheet 1
If the distance between a and 5b is taken and the voltage between the current collecting electrodes is E, then
The following formula holds under the condition that the resistance value per unit area of the resistive film 4 is uniform.

E L Therefore, by finding eX, the X coordinate of point p can be found. Further, after detecting the X coordinate, if the DC voltage is switched and connected to the upper resistor sheet 2 and the lower resistor sheet 1 is opened, the X coordinate of point p will be set to the current collecting electrode 5a of the lower resistor sheet 1 using the same detection principle as described above. It is determined by detecting the voltage e.

[Problem that the invention seeks to solve]

In order to accurately detect the input coordinates, as is clear from equation (1), it is necessary to make the thickness of each resistive film 4.7 constant over the entire surface and to make the resistance value per unit area uniform. be.

However, as a practical matter, it is difficult to form each of the resistive films 4.7 to be a regular film, and some variation in film thickness inevitably occurs. Further, the resistive film 4.7 may be damaged during the manufacturing process or during use, resulting in partial discontinuities.

Furthermore, if the film thickness is uneven or the resistive film is scratched, local differences in the temperature deformation state of the resistive film will increase depending on the operating temperature conditions of the device.
.

The equipotential lines on the resistive film 4, which should be parallel to the resistive film 5b, are distorted.

For example, if the equipotential lines on the resistive film 4 are distorted due to differences in the film thickness of the resistive film, the presence of scratches, or the operating temperature conditions of the device, the il1 equation on the same line parallel to the Y axis in FIG. voltage eX
are different, and although the same X coordinate should be obtained, the values are different, which is inconvenient.

The present invention was made in view of the current status of the coordinate position detection method described above, and its purpose is to compensate for differences in film thickness of resistive films, the presence of scratches, differences in operating temperature, etc., and to minimize local measurement errors. An object of the present invention is to provide a coordinate position detection method that can quickly and accurately detect coordinate positions.

[Means for solving problems]

In order to achieve the above object, the present invention includes two resistor sheets each having a resistor film, and current collecting electrodes extending parallel to both ends of each resistor film of these resistor sheets. In a coordinate position detection method for detecting the coordinate position of the pressing point of a coordinate input device in which each resistive film of a sheet is arranged so that each resistive film faces each other and each electrode is perpendicular to each other, and input is performed by pressing the resistive film. , a plurality of auxiliary electrodes are provided on the resistive film in parallel to the current collecting electrode,
Identifying one of the auxiliary electrodes that sandwich the pressing point, calculating the pressing point position from the voltage of the specified auxiliary electrode and the voltage of the pressing point, and detecting the coordinate position of the pressing point. I decided to do so.

[Effect]

According to the present invention, equipotential lines are formed between the current collecting electrodes of the resistive film by the auxiliary electrodes, and at each pressing point between the auxiliary electrodes in the direction parallel to the auxiliary electrodes, there are Since fluctuations in the voltage value caused by It can be done.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to FIGS. 1 to 8.

FIG. 1 used for detailed explanation of the present invention is a partially cutaway plan view showing the configuration of a coordinate input device used in an embodiment of the present invention, and FIG. Fig. 3 is a circuit diagram of an embodiment of the present invention, Fig. 4 is a flowchart when identifying an auxiliary electrode section sandwiching a pressing point in an embodiment of the present invention, and Fig. 5 is a flowchart when detecting coordinate positions in an embodiment of the present invention. FIG. 6 is a circuit diagram when measuring offset in the embodiment of the present invention, FIG. 7 is a circuit diagram when measuring the voltage of the auxiliary electrodes sandwiching the pressing point in the embodiment of the present invention, and FIG. 8 is the circuit diagram when measuring the offset in the embodiment of the present invention. It is a circuit diagram at the time of press point voltage measurement in the Example of this invention.

As shown in FIGS. 1 and 2, the coordinate input device used in the embodiment of the present invention includes resistive films 4 and 7 of each resistive sheet 1 and 2.
On top are respective current collecting electrodes 5a, 5b.

Multiple linear auxiliary electrodes 13°1 parallel to 8a and 8b
4 are formed of a good conductor such as silver base at equal intervals.

Since a plurality of auxiliary electrodes 13.14 are formed in this way, equipotential lines are formed on the resistive film 4.7 by these auxiliary electrodes, and in narrow sections between the auxiliary electrodes, differences in resistive film thickness, Distortions in the equipotential lines due to the presence of scratches are compensated for by the auxiliary electrodes on both sides, making them extremely small.

In the embodiment of the present invention, when detecting the coordinate position, one of the auxiliary electrodes sandwiching the pressing point is first specified.

For this purpose, pressure detection is performed in the first step of the flowchart shown in FIG. In the circuit used in the example, each auxiliary electrode 13-1. is formed on the resistive film 4 as shown in FIG.
13-2...13-7 has switches Sl, S2.
...One end of S7 is connected in a 0N-OFF manner,
The other end of each switch is connected to terminal T2. Also,
One end of switch wi, W2/old...W8 is connected to each auxiliary electrode 1
3-1.13-2...13-8 0N-OFF
and the other end of each switch is connected to terminal T1. Further, one end of the switch SO is connected to one end of the resistor Rd in an ON-OFF manner, and the other end of the resistor R is connected to the current collecting electrode 8b. Auxiliary electrode 14-1...
...Switch S'O also for 14-8...
- S'7 is connected in exactly the same way.

The other ends of switches W'l to W'8 and switches S°0 to S'
7 is the input terminal tII+txt of the differential amplifier 21
are connected to the input terminals tIIIt!, respectively. ! are connected to terminals Tz and TI, respectively. Further, the output terminal of the differential amplifier 21 is connected to the input terminal of the AD converter 22.

When detecting a press, the switch 10 is switched to the current collecting electrode 5a side, the switch 12 is switched to the neutral position, and the switches SO and S'0 are turned on.

Now, it is assumed that pressing is performed at point p in FIG. 3, and the resistive films 4 and 7 come into contact at point p. In the switching state of the switch as described above, the terminal t2g of the differential amplifier 21 is grounded, and the voltage E of the DC power supply 11 is applied to the switch 5a, the resistive film 4, and the terminal t2g of the differential amplifier 21.
point, resistive film 7, switch SO1 terminal T2 and terminal tl+
is applied to the terminal tl+ of the differential amplifier 21 via the terminal tl+. Therefore, since a detection signal that detects the presence of pressure is obtained from the AD converter 22, it is determined whether or not the pressure has been applied in the second stage of the flowchart in FIG. will be held.

Next, the process proceeds to the third step of the flowchart of FIG. 5, in which the auxiliary electrode section sandwiching the pressing point is detected. Detection of this auxiliary electrode section is performed according to the flowchart shown in FIG.

In this case, in FIG. 3, the switch 10 is the current collector electrode 5a.
The switch SO is turned on, the switch SlO is turned FF, and the switch 12 is turned to the collector electrode 5b side. In this switch state,
The voltage at the pressing point p with respect to the current collecting electrode 5b is applied to the terminal t of the differential amplifier 21 via the resistive film 7 and the switch SO1 terminal T2.
applied to l+.

In this state, the switches WI, W connected to terminals T,
z...W8 is sequentially turned on. First, when the switch WI is turned ON, the voltage of the auxiliary electrode 13-1 with respect to the current collecting electrode 5b is applied to the differential amplifier 2 via the terminal T11.
It is applied to the terminal tz'x of 1. In the differential amplifier 21, the voltage at the pressing point p and the voltage at the auxiliary electrode 13-1 are compared. The processes up to this point are performed in the first and second stages of the flowchart in FIG.

In the third step of the flowchart of FIG. 4, it is compared whether the voltage at the pressing point p and the voltage at the auxiliary electrode 13-1 at the terminal t are greater than a predetermined difference.

The criterion in this case is, for example, that the difference between the two is
The voltage is set to be 1/8 or less of the voltage E of . In this case, since the difference between the voltage of the auxiliary electrode 13-1 and the voltage of the pressing point p is 1/8E or more, the process proceeds to the fourth step of the flowchart in FIG. 4, the switch WI is turned OFF, and the switch W2 is turned OFF. It is turned ON.

By switching this switch, the voltage of the auxiliary electrode 13-2 is changed from the terminal t2 to the terminal t of the differential amplifier 21.

The voltage of the auxiliary electrode 13-2 and the voltage of the pressing point p are compared.

In this case as well, since both voltage values are 1/8E or more, the switch W2 is turned off and the switch W3 is turned on.

In this state, the voltage of the auxiliary electrode 13-3 and the voltage of the pressing point p are compared, and since the difference between the two is less than 1/8E, the process proceeds to the 5th and 7th steps of the flowchart in FIG. ~3 is determined to be the electrode sandwiching the pressing point p,
The third stage of the flowchart of FIG. 5 is completed.

Note that if the auxiliary electrode is selected beyond the pressing point p, the process proceeds to the fifth and sixth stages of the flowchart of FIG. 4, and the direction of selection of the auxiliary electrode is changed.

Next, the process proceeds to the fourth step of the flowchart of FIG. 5, where the offset of the measurement system is measured.

That is, switch S4 and switch W3 are turned on,
Auxiliary electrodes 13-3 sandwiching the pressing point p are connected to the input terminal of the measurement system as shown in FIG. 6, and the offset voltage e''
is measured.

Next, proceed to step 5 of the flowchart in FIG.
The voltage between the auxiliary electrodes 13-3 and 13-4 sandwiching the pressing point p is measured.

For this purpose, in FIG. 3, the switch 10 is switched to the current collecting electrode 5a side, the switch 12 is switched to the current collecting electrode 5b side, the switch S4 and the switch W3 are turned on, and the auxiliary electrode is turned on as shown in FIG. The voltage between 13-3 and 13-4 is measured.

Furthermore, proceeding to step 6 of the flowchart in Figure 5,
The voltage at the pressing point p is measured. For this reason, in FIG. 3, the switch 10 is placed on the collector electrode 5a side, and the switch 1
2 is switched to the current collecting electrode 5b side, and the switch SO is turned on.
Then, the switch SIO is set to ON, and the voltage e' at the pressing point p is detected as shown in FIG.

Next, proceeding to step 7 of the flowchart in FIG. 5, the current is collected using the following formula, where K is the distance between the auxiliary electrodes 13-3 and 13-4, and k is the distance between the current collecting electrode 5b and the auxiliary electrode 13-3. The distance between the electrode 5b and the pressing point p, that is, the X coordinate lx of the pressing point p
is calculated.

The above describes the detection of the X-coordinate position of the pressing point p, but the detection of the X-coordinate position of the pressing point p is also
This can be done in exactly the same way using the auxiliary electrode I4.

The pressure point exists in a narrow area sandwiched between multiple auxiliary electrodes, and the auxiliary electrodes on both sides have respective equipotential lines, so even if the pressure point moves parallel to the auxiliary electrodes, the resistance film Fluctuations in pressure point voltage due to variations in thickness or occurrence of scratches are extremely small.

Therefore, there is no fluctuation in the measured coordinate value due to a change in the pressing point position in the direction perpendicular to the measured coordinate direction. In addition, the resistance path that may include a fluctuation component is shortened, and the ratio of the relatively small voltage value measured across this short resistance path to the voltage value that does not include the resistance fluctuation component measured between the auxiliary electrodes is calculated. The detected value of the coordinate position obtained by the proportional calculation based on the calculation can be obtained with extremely high accuracy.

When these auxiliary electrodes are formed at equal intervals between the current collecting electrodes, the voltages of the auxiliary electrodes can be obtained from the voltage values applied between the current collecting electrodes.

However, the voltage of the auxiliary electrode may fluctuate slightly due to the atmosphere in which the device is used or the aging of the resistive film, so when detecting the coordinate position, the latest voltage value is measured and calculated as in the example. It is desirable to do so. Further, in the embodiment, the coordinate position was detected by specifying one auxiliary electrode 13-3 that sandwiched the pressing point, but it is also possible to specify the other auxiliary electrode 13-4 and detect the coordinate position. .

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to measure the coordinate values of a pressed point using the auxiliary electrode near the pressed point as a reference, thereby providing an extremely high-precision coordinate input device with little measurement error. can do.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway plan view showing the configuration of a coordinate input device used in an embodiment of the present invention, FIG. 2 is a sectional view taken along the IT-II line in FIG. 1, and FIG. A circuit diagram, FIG. 4 is a flowchart for specifying the auxiliary electrode section sandwiching the pressing point in the embodiment of the present invention, FIG. 5 is a flowchart for detecting the coordinate position in the embodiment of the present invention, and FIG. 6 is the flowchart for detecting the coordinate position in the embodiment of the present invention. 7 is a circuit diagram when measuring the voltage of the auxiliary electrodes sandwiching the pressure point in the embodiment of the present invention. FIG. 8 is a circuit diagram when measuring the voltage at the pressure point in the embodiment of the present invention. FIG. 9 is a partially cutaway plan view showing the configuration of a conventional coordinate input device, and FIG. 10 is a sectional view taken along the line I--I in FIG. 9. 1.2... Resistance sheet, 4, 7... Resistance film, 5a. 5b, 8a, 8b... Current collecting electrode, 13.14-... Auxiliary electrode, 21... Differential amplifier, 22... A/D converter. Fig. 1 '4b Sugar Fig. 2 52 va 4 J 13 5b Fig. 3 Soup'' Fig. 4 5 tart Fig. 5 Fig. 6 Fig. 7 Fig. 9 Fig. 3x it [- Fig. 1O

Claims (1)

[Claims] It has two resistive sheets each having a resistive film, and current collecting electrodes extending in parallel to both ends of each resistive film of these resistive sheets, and the resistive films of each of the resistive sheets face each other and each The electrodes are arranged orthogonally,
In the coordinate position detection method of detecting the coordinate position of the pressing point of a coordinate input device in which input is performed by pressing the resistive film, a plurality of auxiliary electrodes are provided on the resistive film in parallel to the current collecting electrode, and the pressing One of the auxiliary electrodes sandwiching the point is specified, and the pressing point position is calculated from the voltage of the specified auxiliary electrode and the voltage of the pressing point, and the coordinate position of the pressing point is detected. A coordinate position detection method characterized by: