JPS58127279A - Co-ordinate detecting device - Google Patents

Abstract

PURPOSE:To eliminate a noise generates in a detecting circuit, etc., by changing a characteristic of a filter in accordance with the cases of pen-down and pen-up. CONSTITUTION:A position co-ordinate is detected by a position co-ordinate detecting device 100. signals corresponding to an (x) co-ordinate and a (y) co- ordinate, which have been detected are outputted to a detected (x) signal terminal 101 and a detected (y) signal terminal 102, respectively. Also, a (z) signal showing up-and-down of a pen is outputted to a detected (z) signal terminal 103. On the other hand, signals from the terminals 101, 102 are inputted to a variable filtering circuit 110 and 111, respectively. When the (z) signal is in a state of showing pen-down, the circuits 110, 111 execute an operation of an LPF having cut-off frequency fL, and when the (z) signal is in a state of showing pen- up, they execute an operation of an LPF having cut-off frequency fH. Also, by setting to fL<<fH, it is possible to smooth the (x) and (y) co-ordinate signal, making a delay of the (x) and (y) co-ordinate signals very small, immediately after the pen-down.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coordinate detection device that detects the position of an input point.

FIG. 1 is a perspective view showing the configuration of a conventional position coordinate detection device, in which 1 is a fixed plate, 2 is a first flexible plate, and 3 is a second flexible plate. parallel electrode group, 4
is one end of the first parallel electrode group 2 that is in contact with IIIK.
The resistor S is KI! on one end side of the second parallel electrode group 3.
The third resistor touched, 6.1 and $, - is the first
This is an electrode provided on the resistor 4°S of 11E2. 10
11 is an insulating substrate, and 11 is a pressure-sensitive rubber sheet that is electrically conductive only in the vicinity of the pressed point. In addition, worms, b, c, and d are terminals provided at both ends of the electrodes s, y, @, and s, respectively, and W represents an input surface.

FIG. 2 is a configuration diagram showing details of the first parallel electrode group 2, in which electrodes Ys-Yse are formed on the insulating base 1 [10].

YM are arranged in parallel. Similarly, the second parallel electrode group 3 in FIG.
t, Xs*..., x's are arranged in parallel. First parallel electrode group 1 and second parallel electrode group 3
are orthogonal, and both parallel electrodes #2.1 face each other in the ^ key, and the first parallel electrode #P! There is a pressure sensitive rubber sheet 11 between the parallel electrode #3 and the second parallel electrode #3.
When drawing the input image Wk uppercase figure which is the layer surface of the parallel electrode group 3, conduction occurs at the point where the pressure sensitive rubber sheet 11 is pressed due to linear pressure, and the first parallel electrode 11#2 and the parallel electrode *g 5 so that each one electrode in detail 3 is conductive.

Figure m3 is a detailed diagram of a conventional position detection circuit, and is a 12tt
Constant @ current source, 13.14 is: t bear: /p, 15° 16 is a microresistor, 1r and 1s are the X output terminal and Y output terminal e, 11 is the current detection circuit, 20 is the pentawan output It is a terminal. Note that other symbols indicate the same parts as in FIG.

In order to operate this, in FIG. 1, the input surface VdK1 is located above the part where the parallel electrode group 2 of 11 and the parallel electrode group 3 of #I2 overlap.

When a figure or the like is inserted, the pressure-sensitive rubber sheet 11 becomes electrically conductive, and one electrode in each of the second parallel electrode group 3 and the first parallel electrode #2 becomes electrically conductive due to the pressure of the pen.

Therefore, as shown in FIG. 3, the X and Y coordinates can be detected by the currents flowing in and out of the terminals - and 1cfi, and the currents flowing in and out of the terminals C and 1cfi.

However, as shown in Fig. 4, an example of the output waveform is shown in Fig. 5. As the input point moves, the output waveform becomes step-like, and noise is added due to the pressure-sensitive rubber seal (see Fig. 11). , there was a drawback if the detection accuracy was significantly impaired.

In order to eliminate these drawbacks, the present invention provides a position coordinate detection device with the function of a low filter only while it is pendant. Learn more about JiKli! I will clarify.

FIG. 5 shows an embodiment of the present invention, in which 110 is a position coordinate detection device, 101 is a detection X signal terminal, and 102 is a detection y
Signal terminal, 10'l is detection 2 signal terminal, 110 and 1
11 is a variable filter circuit, 112 is a 2-signal processing circuit, 1
21 is a 2-signal output terminal, 121 is a y-signal output terminal, 12
2 is a two-signal output terminal.

FIGS. 6(&) to (e) are signal waveform diagrams for explaining the present invention in detail.

#17 Figure is the variable filter path 11@ shown in Figure 5.

111, 130 is "coordinate signal input terminal, 1
31 is a switching signal input terminal, 132 is a coordinate signal output terminal, and 133 is an operational amplifier. Also, a turtle.

Rg, R'+, R'm are resistors, C is capacitor, T
I.

■ is an analog switch.

48(a) to (d) are the variable filter circuit 11 of FIG.
0.111 is a waveform diagram for explaining the operation.

Next, the operation of the embodiment shown in FIG. 5 will be explained using FIG. 6.

The position coordinates are detected by a position coordinate detection device 10G constructed using a conventional technique. Signals corresponding to the detected X and y coordinates are respectively connected to the detection X signal terminal 1.
01. The detected y signal is output to terminals 1 and 2. In addition, the 2nd signal indicating the 7th stroke of the pen is sent to the detection 2nd signal terminal 101.
is output to.

The detected two signals enter the two-signal processing circuit 111 and perform processing as shown in section 611(e)K.
The product of the input signal shown in FIG. 6(a) K and the input signal delayed by a certain time τ0 as shown in FIG. 6(b) K is obtained.

On the other hand, the detection X signal terminal 101 and the detection y signal terminal 10
The signals from the variable filters 1] and 110 .
Enter 111. When the 2 signals indicate pen-up, the variable filter circuits 110 and 111 operate as a low-pass filter with a cut-off frequency f, and when the 2 signals indicate pen-up, the variable filter circuits 110 and 111 operate at the cut-off frequency afwIk.
-The operation of the low-pass filter with 5 degrees is as described below.
By setting f L << fm, immediately after Penmewan x, yI! While minimizing the delay of the target signal, x,
This can be solved by smoothing the y-coordinate signal.

Next, an example of how to configure the variable filter circuits 110 and 111 will be described.

If the circuit shown in FIG. 7<=, the switching signal input terminal 131
When the switching signal input from the switch indicates pen-down, the analog switches Tt and Tm are non-conducting, and when the switching signal indicates pen-up, the analog switches T, , T* are conducting. ing. therefore,
The transmission relationship between the signal ν1 inputted from the coordinate signal input terminal 13G and the signal V outputted to the coordinate signal output terminal 132 is as follows.

However, ω is the angular frequency. Also, R, m is switching 1
When No. 6 is pen down, frK is)t-R, +R,,R=straight+R'.

So, when the switching signal is pen 7 sub, R = R1, R
= Rt. Here, R+ = R'+, R* = R*, CRt
= 1/f weight.

If the element constants are selected so that CR dew = t/ft 1/fs+, the DC gain will not change due to pen-down or pen-up foreshadowing.

Only the cutoff frequency can be changed. Note that since there are several degrees of freedom between each element, a variable filter can be configured without setting constants as described above.

By doing this, the X or Y coordinate signal (FIG. 8(a)) from the position coordinate detection device 100 can be changed to two signals (
By switching in Figure 8 (@)), Figure 8 (
b) The signal is smoothed as shown by K. Note that the switching response time and rise time T of the variable filter circuits 110 and 111.

However, if the two signals are delayed as shown in the 8th wA(d), the correct x and y coordinates immediately after the pendant 9 can be obtained.

As described in detail above, 1. This invention can smooth the rising or falling delay of the coordinate (11-1) by varying the filter characteristics at pen-down time and pen-up time. Therefore, there is an advantage that noise generated in the detection circuit etc. can be removed. Further, the x and y coordinate signals from the position coordinate detection device have a step-like waveform depending on the distance between the electrode sheets, but according to the present invention, intermediate values are interpolated, so the equivalent This has the advantage that the resolution of the position coordinate detection device can be improved.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a configuration example of a conventional position coordinate detection device, FIG. 2 is a perspective view showing a configuration example of a parallel electrode group in FIG. 1, FIG. 3 is a conventional position detection circuit diagram, and FIG. The figure is an output signal waveform diagram obtained from a conventional position coordinate detection device, and FIG. 5 is a gang diagram showing one embodiment of the present invention.
a) to (4t) are waveform diagrams of the two signal processing circuits of the embodiment shown in Figure 5, Figure 7 is a detailed diagram of the variable filter circuit, and Figure 8 is a detailed diagram of the variable filter circuit.
Figures (a) to (d) are waveform diagrams for explaining the operation of the embodiment of Figure 5. In the figure, 100 is a position coordinate detection device, 101 is a detection X signal terminal, 102 is a detection Y signal terminal, 103 is a configuration 2 terminal, and 110.111 is a variable filter 1g1w! , 112
2 signal processing circuit, 120 is an X signal output terminal, 121 is a y signal output terminal, 122 is an X signal output terminal, 130 is a coordinate signal input terminal, 131 is a switching signal input terminal, 132
1 is a coordinate signal output terminal, and 133 is an operational amplifier. Figure 1 d Figure 2 Figure 3

Claims (1)

[Scope of Claims] A position coordinate detection device that detects position coordinates and outputs a signal indicating X-coordinates and pe/da-kun, and a low-pass filter whose cutoff frequency l! can be changed by bend-a-one and pen-up. , a means for lowering the cutoff frequency of the low-pass filter in the pen-up state to be high<L; and a means for lowering the cut-off frequency of the low-pass filter in the pen-down state.