JPH0443293B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a system in which, when a figure, etc. is drawn on a tablet board with a stylus, the position of the stylus on the tablet board is sequentially detected. A graphic display device or graphic creation device that obtains data such as graphics, and uses this data to display graphics, etc. on a cathode ray tube display device, or to change the display on the cathode ray tube display device. The present invention relates to a position detection device suitable for use as a part that includes a stylus.

BACKGROUND TECHNOLOGY AND PROBLEMS The above-mentioned position detection device has a position detection plate constituting a tablet board and a stylus whose position on the position detection plate is detected. , one in which the position of the stylus is detected by an electrostatic method has been proposed.

FIGS. 2 and 3 show an example of such a position detection device, and a position detection plate 10 constituting a tablet board has a plurality of strip conductors Y ₁ , Y ₂ on an insulating layer 11.
...Y _n are arranged in parallel at regular intervals, and on the insulating layer 12 deposited on the insulating layer 11, a plurality of strip conductors Y ₁ , Y ₂ ... orthogonal to Y _n are formed. The strip conductors X ₁ , X ₂ ...X _o are the strip conductors Y ₁ , Y ₂
. . . The structure is such that insulating layers 13 are deposited and are arranged in parallel with the same center spacing as the center spacing of Y _n . Further, the stylus includes a detection electrode 31 forming a voltage detection means disposed on the insulating layer 13 of the position detection plate 10, and a capacitor having a capacitance Cf is connected between the detection electrode 31 and the ground. It is done. Moreover, the strip conductors X ₁ , X _{2 .} . . X _o of this position detection plate 10 and the strip conductors Y ₁ ,
A switch circuit 22 is connected to one end of each of Y ₂ ... Y _n .
switches 22 ₁ , 22 ₂ ... 22 _o and switches 23 ₁ , 23 ₂ ... 23 _n of the switch circuit 23 are provided, and these switch circuits 22 and 23
The terminal A side of each switch is grounded, and the terminal B side is connected to a common voltage supply terminal 21.

Then, within a certain period of time, pulse signals of a certain width are sequentially applied from the output terminals N ₁ , N ₂ . . . _No of the shift register 24 to the switches 22 ₁ , _{22 2} . , switches 22 ₁ , 22 _{2 ,} . . . , 22 _o are sequentially switched from the terminal A side to the terminal B side at regular intervals. As a result, as shown in FIG. 4, the strip conductors X ₁ , X ₂
...For each of X _o , sequentially for each period of unit time Ts,
A predetermined voltage Vcc is supplied from the voltage supply terminal 21. In addition, within a certain period other than this,
Similarly, the output terminals M ₁ and M ₂ of the shift register 25
...from M _n to the switch 23 ₁ of the switch circuit 23,
Pulse signals of a constant width are sequentially applied to the terminals 23 2 . . _. 23 _n , and the switches 23 _{1 ,} 23 ₂ . As a result, in the same manner as in the case _{of the} strip conductors _{X 1} , X _{2 .} . . A voltage of Vcc is supplied.

Here, if the capacitance formed between the strip conductor to which voltage Vcc is applied and the detection electrode 31 is Cp, the signal voltage Vo obtained at the detection electrode 31 at that time is Vo=Cp/Cp+CfVcc. The larger the capacitance Cp is, the more the voltage Vcc is applied to the strip conductor and the sensing electrode 3.
1, the signal voltage Vo becomes larger. Therefore, the strip conductors X ₁ , X ₂ ...X _o or Y ₁ ,
When voltage Vcc is sequentially supplied to Y ₂ ... Y _n as described above, an electrostatic charge is formed between the strip conductor to which voltage Vcc is supplied and the detection electrode 31, as shown in FIG. As the capacitance Cp sequentially changes for each unit time Ts, the signal voltage Vo obtained at the detection electrode 31 changes stepwise for each unit time Ts, and the strip conductors X ₁ , X ₂ . . . X _o or Y ₁ , Y ₂ ...
When the voltage Vcc is applied to the one of _Yn closest to the position of the detection electrode 31, the maximum value Vm is obtained.
However, the signal voltage Vo is actually obtained only when the voltage Vcc is applied to several strip conductors before and after the detection electrode 31, as shown in FIG. 6A. When the voltage Vcc is applied to a strip conductor located further away, the voltage becomes almost zero.

Based on this signal voltage Vo, the strip conductors X ₁ and X ₂ on the position detection plate 10 of the detection electrode 31
...X direction which is the arrangement direction of X _o and the strip conductor Y ₁ ,
Y ₂ ...The position in the Y direction, which is the arrangement direction of Y _n , is detected. Specifically, the signal voltage Vo obtained at the detection electrode 31 is supplied to the tuned amplifier circuit, and as shown in FIG. 6B, the signal voltage Vo reaches the maximum value Vm.
A signal Sb of a predetermined frequency that reaches its maximum amplitude after a certain time delay from the point in time when A signal that falls from high level to low level when it crosses the positive level Vs of
Sz is obtained. And the strip conductors X ₁ , X ₂ ...X _o
or strip conductors Y _{1 , Y 2 . .} . Y During the period up to the time _t2 when the signal Sz first rises, the counter counts the clock pulses whose period is sufficiently shorter than the unit time Ts mentioned above, thereby detecting the period Td from the time _t1 to the time _t2 . The output data of the counter at time _t2 is taken out as a detection output of the position of the detection electrode 31 on the position detection plate 10 in the aforementioned X direction or Y direction.

By the way, in the position detection plate 10, the strip conductor
X ₁ , X ₂ ... The surface where X _o is arranged and the strip conductor Y ₁ , Y ₂ ...
The surface on which Y _n is arranged is separated by the thickness of the insulating layer 12 in the thickness direction of the position detection plate 10. Therefore, the strip conductor X ₁ at a certain position on the position detection plate 10, One of the _strip conductors _{Y 1 , Y 2} . Furthermore, the capacitance Cp formed between the strip conductor to which the voltage Vcc is supplied and the detection electrode 31 becomes smaller as the distance from the strip conductor to the detection electrode 31 increases; It becomes larger as the width of the strip conductor becomes larger.

For this reason, as shown in Figure 2, the strip conductor
Each of Y ₁ , Y ₂ ……Y _n is a strip conductor X ₁ , X ₂ ……X _o
The strip conductor X ₁ ,
In the case of position detection in the X direction where the voltage Vcc is sequentially supplied to X ₂ ... X _o , and the voltage is applied to the strip conductors Y ₁ , Y ₂ ... Y _n
The change in the maximum value Vm of the signal voltage Vo obtained at the detection electrode 31 is made small in the case of position detection in the Y direction in which Vcc is sequentially supplied.

However, in the conventional position detection plate 10, each of the strip conductors X ₁ , X _{2 . .} .
Y ₁ , _{Y 2} . . . Y
The change in the maximum value Vm of the signal voltage Vo in the case of position detection in the direction is not made small enough. This is because when making the widths of the strip conductors X ₁ , X _{2 .} . . It becomes difficult to form,
Further, the width of each of _the strip conductors Y ₁ , Y ₂ . and strip conductor
Y ₁ , Y ₂ ……Strip conductor to increase the width of each Y _n
If the pitch of Y ₁ , Y _{2 .} . . Y _n is increased, the accuracy of position detection will decrease.

Also, the maximum value Vm of the signal voltage Vo in the case of position detection in the X direction and in the case of position detection in the Y direction.
In order to minimize the change in the strip conductors X ₁ , X ₂ ...X _o
It is conceivable to reduce the thickness of the insulating layer 12 that separates the surface where the strip conductors Y ₁ , Y _{2 .} . . layer 1
Since it is formed using a transparent adhesive to bond 1 and 13 together, it cannot be made smaller than a certain level.

As mentioned above, when there is a change in the maximum value of the signal voltage Vo between the case of position detection in the X direction and the case of position detection in the Y direction, the value obtained based on the signal voltage Vo is shown in FIG. 6B. As a result, the amplitude of the signal Sb changes, and there is a possibility that the position detection output obtained based on the signal Sb may contain an error.

Purpose of the Invention In view of the above, the present invention provides a position detection plate having a plurality of first strip conductors arranged in the X direction,
Then, a voltage is sequentially applied to a plurality of second strip conductors arranged in the Y direction, for example, on a surface that is farther from the voltage detection means than the surface on which the first strip conductors are arranged. When the position of the voltage detecting means on the position detecting plate is detected based on the signal voltage obtained from the voltage detecting means, a voltage is supplied to the plurality of first strip conductors. The difference in the level of the signal voltage obtained from the voltage detection means is effectively reduced between the case of position detection performed by supplying voltage to the plurality of second strip conductors and the case of position detection performed by supplying voltage to the plurality of second strip conductors. The purpose of the present invention is to provide a position detection device that has the following characteristics.

Summary of the Invention A position detection device according to the present invention includes a plurality of first strip conductors arranged in parallel at a predetermined interval on one side of an insulating layer, and a plurality of first strip conductors arranged in parallel at a predetermined interval on the other side of an insulating layer. a position detection plate having a plurality of second strip conductors arranged in a direction intersecting the first strip conductor; a drive unit that sequentially supplies the first voltage and supplies a second voltage higher than the first voltage to each of the plurality of second strip conductors for a predetermined period in the order in which they are arranged; voltage detection means placed on the position detection plate from one side of the insulating layer and obtaining a voltage output based on the first or second voltage supplied to the first or second strip conductor; and a position data generating section that obtains a position detection signal representing the position of the voltage detection means on the position detection plate based on the voltage output from the detection means.

By doing so, each of the second strip conductors disposed on a surface where the distance from the voltage detection means is greater than the surface on which the first strip conductor is disposed,
A voltage higher than the voltage sequentially supplied to each of the first strip conductors is supplied, and the voltage can be applied to the first strip conductor without changing the configuration of the position detection plate. detecting the position of the voltage detecting means in the arrangement direction of the first strip conductor;
A second conductor is supplied with a voltage to the second strip conductor.
When detecting the position of the voltage detecting means in the arrangement direction of the strip conductors, the difference in the level of the voltage output obtained from the voltage detecting means can be significantly reduced.

Example Examples of the present invention will be described below.

FIG. 1 shows an example of a position detection device according to the present invention. In FIG. 1, parts corresponding to those shown in FIG. 2 are designated by the same reference numerals as those in FIG. 2, and detailed explanation thereof will be omitted.

This example includes a position detection plate 10, switch circuits 22 and 2 similar to those shown in FIGS.
3 and shift registers 24 and 25. The difference from the position detection device shown in FIG. 2 is that the terminal B side of each of the switches 22 ₁ , _{22 2 .} 2
1, while the voltage Vcc is supplied through the switches 23 ₁ , 23 ₂ . . . 23 _n of the switch circuit 23.
Each terminal B side of
A voltage Vcc' higher than Vcc, for example, about 1.6 times the voltage Vcc, is supplied. Therefore, the strip conductor of the position detection plate 10
X ₁ , X _{2 . .} .
When each of 2 ₁ , 22 ₂ ...22 _o is switched from the terminal A side to the terminal B side, the voltage Vcc changes over a unit time.
The strip conductors Y ₁ ,
Y ₂ ...Y _n is connected to switch 2 from the switch circuit 23 by a pulse signal from the shift register 25.
When each of 3 ₁ , 23 ₂ . . . 23 _n is switched from the terminal A side to the terminal B side, the voltage Vcc' is sequentially supplied for each unit time Ts.

The strip conductors X ₁ , X ₂ . . . of such position detection plate 10
In order to drive the shift registers 24 and 25 to supply voltage to X _o , Y ₁ , Y ₂ . . . Y _n ,
A clock pulse generation circuit 41, a frequency division circuit 42 and a signal generation circuit 43 are provided.

From the clock pulse generation circuit 41, for example,
A basic clock pulse Co of 2400 KHz is obtained, and this clock pulse Co is supplied to a frequency divider circuit 42 and frequency-divided to obtain a clock pulse Cs of, for example, 60 KHz as shown in FIG. 7. This clock pulse Cs is supplied to the signal generation circuit 43, which has a period corresponding to the unit detection period Tx and Ty as shown in FIG. 7, and a pulse width of one period of the clock pulse Cs. Detection start signal Sp and this detection start signal
Drive start signal St delayed by one cycle of clock pulse Cs with respect to Sp, and detection start signal
A detection period identification signal Sxy whose level is inverted every cycle of Sp, a signal Stx consisting of a pulse during a period Tx in which the detection period identification signal Sxy of the drive start signal St is at a high level, and a signal Stx of the drive start signal St. detection period period during which the identification signal Sxy is at a low level
A signal Sty consisting of pulses at Ty is obtained.

Then, the clock pulse Cs is supplied to the shift register 24 as a shift pulse, and the signal Stx is supplied to the shift register 24 as a start pulse, and a period of n cycles of the clock pulse Cs starts from the leading edge of the signal Stx within the period Tx. During the drive period up to the point in time, the output terminals N ₁ , N _{2 .} . . _x1 , P _x2 ...
P _xo is the unit time Ts for one cycle of clock pulse Cs
These pulse signals P _x1 , P _x2 are obtained sequentially for each period of
...P _xo is the switch 22 ₁ , 2 of the switch circuit 22
2 ₂ ...22 _o , and switches 22 ₁ , 2
2 ₂ ...22 _o is sequentially switched from the terminal A side to the terminal B side for each unit time Ts corresponding to one period of the clock pulse Cs, and as a result, the strip conductors X ₁ , X ₂ ...
…The voltage Vcc from the voltage supply terminal 21 is applied to X _o ,
Unit time Ts for one cycle of clock pulse Cs, respectively
will be supplied sequentially for each period.

Similarly, the clock pulse Cs is supplied to the shift register 25 as a shift pulse, and the signal Sty is supplied to the shift register 25 as a start pulse, and a time period of m periods of the clock pulse Cs starts from the leading edge of the signal Sty within the period Ty. During the driving period up to the point in time when the clock pulse Cs elapses, the output terminals M ₁ , M _{2 .} . . _y1 , _Py2 ...
P _yn is the unit time Ts for one period of the clock pulse Cs
These pulse signals P _y1 , P _y2 are obtained sequentially for each period of
...P _yn is the switch 23 ₁ , 2 of the switch circuit 23
3 ₂ ...23 _n , and switches 23 ₁ , 2
3 _{2 .} . . 23 _n is sequentially switched from the terminal A side to the terminal B side for each unit time Ts corresponding to one cycle of the clock pulse Cs, and as a result, the strip conductors Y ₁ , Y ₂ .
...Voltage from voltage supply terminal 21' to Y _n
Vcc′ (Vcc′≒1.6Vcc) is equal to each clock pulse Cs
It is sequentially supplied for a period of unit time Ts corresponding to one period of .

Voltage detecting means 3 forming a stylus for drawing figures etc. on a position detecting plate 10 forming a tablet board
0 is equipped with a detection electrode 31, and the detection electrode 31 is placed on the position detection plate 10 with its head facing the outside of the grounded shield case 33, and inside the shield case 33. It is grounded via a capacitor 32 having a capacitance Cf.
Further, the detection electrode 31 is connected to the gate of a field effect transistor 34 inside the shield case 33, and a bias resistor 35 is connected between the gate of the field effect transistor 34 and a ground potential point. Then, in the period Tx, the strip conductors X ₁ , X ₂ ...
The capacitance Cp formed between the detection electrode 31 and the one to which the voltage Vcc from the voltage supply terminal 21 of _Xo is supplied changes sequentially in units of time Ts corresponding to one period of the clock pulse Cs. Along with this, the level of the signal voltage Vo obtained at the detection electrode 31 also changes, and the voltage is supplied to the strip conductor closest to the position of the detection electrode 31 among the strip conductors X ₁ , X ₂ ...X _o . It becomes maximum when voltage Vcc from terminal 21 is supplied. Similarly, in the period Ty, the strip conductors Y ₁ , Y ₂ ...
...Voltage from voltage supply terminal 21' of Y _n
The capacitance Cp formed between the detection electrode 31 and the one to which Vcc' is supplied changes sequentially for each unit time Ts corresponding to one period of the clock pulse Cs. Signal voltage Vo
The level also changes, reaching a maximum when the voltage Vcc' from the voltage supply terminal 21' is supplied to the strip conductor closest to the detection electrode 31 among the strip conductors Y ₁ , Y ₂ . . . Y _n . Become.

Here, the detection electrodes 31 on the position detection plate 10 and the strip conductors X ₁ , X ₂ . _{. .}
The strip conductor Y ₁ , which is arranged in a plane with a large distance from the detection electrode 31 and to which the detection electrode 31 and the voltage Vcc' are supplied, is compared to the capacitance Cp between the detection electrode 31 and the voltage Vcc'.
Although the capacitance Cp between Y ₂ ... Y _n becomes small, the voltage Vcc' is about 1.6 times higher than the voltage Vcc, so that the strip conductors Y ₁ , Y ₂ ... ...The case where position detection is performed in the Y direction, which is the arrangement direction of Y _n , and the case where the position detection is performed in the Y direction, which is the arrangement direction of Y _n , and the case where the position detection is performed in the _{Y direction} , which is the arrangement direction of the strip conductors
The maximum value Vm of the signal voltage Vo obtained at the detection electrode 31, expressed by the above-mentioned Vo=Cp/Cp+CfVcc, is made approximately equal in the case where the position in the direction is detected.

The signal voltage Vo obtained at the detection electrode 31 passes through the field effect transistor 34 to the tuned amplifier circuit 5.
1 and is supplied to 2 after a certain time delay from the time when the signal voltage Vo reaches its maximum, as shown in FIG.
At each point in time, a signal of a predetermined frequency with a large peak level portion becomes Sbx during period Tx,
Moreover, in the period Ty, it is obtained as Sby.
These signals Sbx and Sby have approximately the same amplitude because the maximum value Vm of the signal voltage Vo is approximately equal when the position is detected in the X direction and when the position is detected in the Y direction. .

The signals Sbx and Sby obtained in this way are
The seventh
As shown in the figure, the signals Sbx and Sby fall from high level to low level when they cross a predetermined positive level Vs to be greater than this level Vs, and then the signals Sbx and Sby fall below the ground potential. A signal Sz that rises from a low level to a high level is obtained when the signal crosses from positive to negative.

The drive start signal St obtained from the signal generation circuit 43 is supplied to the set terminal S of the RS flip-flop circuit 53, and the signal Sz obtained from the Schmitt trigger circuit 52 is supplied to the reset terminal R of the RS flip-flop circuit 53. RS
From the flip-flop circuit 53, the strip conductor X ₁ to
Time t ₁ when voltage Vcc or Vcc' is applied to Y ₁ , respectively
Then, after the signal Sbx or Sby from the tuned amplifier circuit 51 exceeds the level Vs, the signal from the Schmitt trigger circuit 52 crosses the ground potential from positive to negative for the first time.
A signal that falls at the time t ₂ when Sz first rises
Gc is obtained.

Then, the clock pulse Co obtained from the clock pulse generation circuit 41 and the signal Gc obtained from the RS flip-flop circuit 53 are supplied to the AND gate circuit 55, and during the high level period of the signal Gc,
That is, in the period Td from time t ₁ to time t ₂ ,
Clock pulse Co is extracted.

On the other hand, the detection start signal Sp obtained from the signal generation circuit 43 is supplied to the clear terminal CLR of the counter 54, and the counter 54 is cleared at the beginning of the period Tx or Ty, and the period after this counter 54 is cleared. During the high level period of the signal Gc in Tx to Ty, the clock pulses obtained from the AND gate circuit 55 are supplied to the clock terminal CK of the counter 54 and counted. By this,
The time from time t ₁ to time t ₂ , and therefore the output data of the counter 54 corresponding to this time, corresponds to the conductor strips X ₁ , X ₂ . _. .
Y ₁ , Y ₂ ...Distance from the reference one (first strip conductor X ₁ to Y ₁ ) of Y _n , that is, depending on the position in the X direction or Y direction, and therefore, In the period from the fall of the signal Gc obtained from the RS flip-flop circuit 53 in the middle of the period Tx to the leading edge of the detection start signal Sp obtained from the signal generation circuit 43 thereafter, the counter 54 calculates the following values:
The position of the detection electrode 31 at that time is X on the detection plate 10
It holds the output data indicating the position in the direction, and from the fall of the signal Gc obtained from the RS flip-flop circuit 53 in the middle of the period Ty to before the detection start signal Sp obtained from the subsequent signal generation circuit 43. In the period up to the edge, the content indicating the position of the detection electrode 31 on the position detection plate 10 in the Y direction at that time is held. The output data of this counter 54 is then supplied to a data processing circuit 57.

Note that the signal from the Schmitt trigger circuit 52
Sz is supplied to the set terminal S of the RS flip-flop circuit 56, and the detection start signal Sp obtained from the signal generation circuit 43 is supplied to the RS flip-flop circuit 5.
6, a signal Sa is obtained from the RS flip-flop circuit 56 which becomes high level during the period in which the output data of the counter 54 is indicative of the time period Td.
The output data of the counter 54 and the detection period identification signal Sxy obtained from the signal generation circuit 43 are supplied to the data processing circuit 57.
Thus, data as a detection output of the position of the detection electrode 31 on the position detection plate 10 in the X direction and the Y direction can be obtained.

As described above, when detecting the position in the X direction and in the Y direction,
Signal voltage from detection electrode 31 when detecting position in direction
Since the signals Sbx and Sby obtained from the tuned amplifier circuit 51 based on Vo are made to have substantially equal amplitudes, the first rising edge of the signal Sz obtained from the Schmitt trigger circuit 52 occurs during the period Tx.
and the period Ty, that is, when detecting the position in the X direction and when detecting the position in the Y direction.
The counter 5 is obtained under the same conditions as when detecting the position in the direction, and as a result, the counter 5 has contents representing the position of the detection electrode 31 on the position detection plate 10.
The output data of No. 4 contains no errors.

Effects of the Invention As is clear from the above description, according to the position detection device according to the present invention, the position detection plate, for example,
a plurality of first strip conductors arranged in a direction;
For example, a plurality of second strip conductors arranged in the Y direction are placed on a surface that is farther from the voltage detection means arranged on the position detection plate than the surface on which the first strip conductors are arranged. When voltage is sequentially supplied to the strip conductors and the position of the voltage detection means on the position detection plate is detected based on the signal voltage obtained from the voltage detection means, the voltage of the plurality of second strip conductors is detected. Since the voltage supplied to each of the plurality of first strip conductors is selected to be higher than the voltage supplied to each of the plurality of first strip conductors,
The voltage detection means can be used to detect the position in the arrangement direction of the first strip conductor and to detect the position in the arrangement direction of the second strip conductor without changing the configuration of the position detection plate. The levels of the signal voltages obtained can be made equal. Therefore, the position detection state is made equal when the position is detected in the arrangement direction of the first strip conductor and when the position is detected in the arrangement direction of the second strip conductor, and the detection error is reduced. significantly reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an example of a position detection device according to the present invention, FIG. 2 is a schematic configuration diagram showing a part of a conventional position detection device, and FIG. 3 is a diagram of the position detection device shown in FIG. 2. The cross-sectional views of the position detection plate, FIGS.
This figure is a waveform diagram used to explain the operation of the example shown in FIG. 1. In the figure, 10 is a position detection plate, 21 and 21' are voltage supply terminals, 22 and 23 are switch circuits, and 24
and 25 is a shift register, 30 is a voltage detection means, 31 is a detection electrode, 43 is a signal generation circuit, and 51
is a tuned amplifier circuit, 52 is a Schmitt trigger circuit, 54 is a counter, 57 is a data processing circuit,
X ₁ , X ₂ ...X _o and Y ₁ , Y ₂ ... Y _n are strip conductors.

Claims (1)

[Claims] 1 A plurality of first strip conductors arranged in parallel at predetermined intervals on the first surface side of the insulating layer, and a plurality of first strip conductors arranged in parallel at predetermined intervals on the second surface side of the insulating layer opposite to the first surface. a position detection plate having a plurality of second strip conductors arranged in parallel in a direction intersecting the first strip conductors; 1 in order of their arrangement by period
a driving section that supplies a voltage higher than the first voltage to each of the plurality of second strip conductors for a predetermined period and sequentially in the order in which they are arranged; Voltage detecting means placed on the position detecting plate from the first surface side and obtaining a voltage output based on the first or second voltage supplied to the first or second strip conductor; and a position data generating section that obtains a position detection signal representing the position of the voltage detection means on the position detection plate based on the voltage output from the voltage detection means.