JPH0383113A - Coordinate detector - Google Patents

Abstract

PURPOSE:To prevent erroneous detection by generating a read timing signal only in the period when an output coordinate detection signal is stable and excluding an influence of chattering to read the output coordinate detection signal regardless of this influence included in the output coordinate detection signal. CONSTITUTION:The read timing signal for an output x-direction coordinate detection signal Ox' and an output y-direction coordinate detection signal Oy' is generated by a fourth integrating circuit 14 and a second comparing circuit 15. The integral rise time constant of the fourth integrating circuit 14 is set to a value longer than those of second and third integrating circuits 12 and 13, and the reference level of the second comparing circuit 15 is so determined that the integral output of the fourth integrating circuit 14 is allowed to pass as the read timing signal after the completion of rise of the output x-direction coordinate detection signal Ox' and the output y-direction coordinate detection signal Oy'. Thus, an influence of chattering is not included in output coordinate detection signals read in based on the read timing signal though chattering has an influence upon output coordinate detection signals Ox' and Oy'.

Description

[Detailed description of the invention]

<Industrial Field of Application> The present invention is used to detect input coordinate positions in CAD, personal computers, etc., and two resistive film sheets arranged facing each other are brought into contact by pressing a touch pen, and the The present invention relates to a coordinate detection device that detects the coordinate position of a contact point based on the level of an output signal in a pressure-sensitive tablet configured to output a signal with a level corresponding to the coordinate position of the contact point. <Prior Art> The schematic structure of a general pressure-sensitive tablet is shown in FIG. 3, and in the pressure-sensitive tablet A described below, a y-coordinate sensing resistive film sheet 1 and an are arranged parallel to each other with a minute gap in between. In the y direction, one end of the y-coordinate sensing resistive film sheet 1 is connected to a constant current power source 3, and the other end is connected to the constant current power source 3 via a current sensing resistor R3. Both ends of the current detection resistor R are connected to the double-blade terminal of the differential amplifier 4, and the y-direction coordinate detection signal Oy is output from its output terminal. In the X direction, both ends of the X coordinate sensing resistive film sheet 2 are connected to each other via an IIT flow sensing resistor R1. 1
Both ends of the tfL protruding resistor R1 are connected to the double-blade terminal of the differential amplifier 5, and the X-direction coordinate detection signals O,
It is designed to output l. A voltage detection resistor R3 is connected between the ground and the connection point between one end of the X-coordinate detection resistive film sheet 2 and the current detection resistor R2, and outputs the voltage across the voltage detection resistor R1 as a pen up/down signal O1. It looks like this. By pressing the two resistive film sheets 1 and 2 with a touch bench, both the resistive film sheets 1 and 2 are brought into contact at an arbitrary point P. Each distance from the contact point P to both ends of the y-coordinate sensing resistive film sheet 1 is y++ yi, and the supply current of the constant current power supply 3 is I
When tfL flowing through ll and current detection resistor R is i, yl + y! Since yi X11 0 and i6.0'+ yz) are constant, the y-direction coordinate position y of the contact point P is proportional to the current 11 flowing through the current detection resistor R8. Differential amplification! Since the magnitude of the y-direction coordinate detection signal O7 outputted from lS4 is R, xi, the y-direction coordinate value W y + of the contact point P can be detected by the y-direction coordinate detection signal 0. Further, if each distance from the contact point P to both ends of the X-coordinate sensing resistive film sheet 2 is "I + xz", and the current flowing through the current sensing resistor R8 is it, then X, +Xt Xl-X11 i. Since XI+1 is constant, the X-direction coordinate value fx+ of the contact point P is proportional to the current 12 flowing through the current detection resistor R.The magnitude of the X-direction coordinate detection signal 08 output from the differential amplifier 5 are R, Xi, so the X-direction coordinate position x of the contact point P can be detected by the X-direction coordinate detection signal 08. Furthermore, e6=R3Xi
, a constant voltage appears, but when the touch pen is released and the current stops flowing, the voltage becomes 0, so the voltage across the voltage detection resistor R1 is changed to the pen up/down signal Of
By extracting this as When the touch ben is moved with the touch ben down and both resistive film sheets 1.2 in contact with each other, each signal 01.
○8,0. Ideally, it should be as shown in FIG. 4(a). In the conventional example, the X-direction coordinate detection signal Oy and the y-direction coordinate detection signal Oy are sampled during the period when the pen up/down signal 01 is "H". However, in reality, the hand holding the touch pen As vibration and fluctuations in pressing force are unavoidable, chattering occurs in which both resistive films 1 and 2 repeat contact and non-contact at minute intervals, resulting in a distorted waveform as shown in Figure (b). In other words, even though the touch pen is down, the detection signal becomes "0 level" due to chattering, so it may be mistakenly detected as being up, or the contact point P may be incorrectly detected.
Although it is not on the X axis or the y axis,
If it is on the axis or the y-axis, it will be falsely detected. In order to eliminate this chattering noise, in the conventional coordinate detection device, as shown in FIG. Take out, human power X direction coordinate detection signal 0. 1, input y-direction coordinate detection signal Oa, and output X-direction coordinate detection signal 0.1, output y-direction coordinate detection signal 0. It is configured to be extracted as / . Even during the period when the signal becomes "O" level due to chattering, the input coordinate detection signal 0. ．． 0. Since it is necessary to maintain the level of the previous level, the integration time constant τ of the integration circuit 8.
2. τ is set sufficiently large. These integral time constants τ2. τ prevents overshoot and high frequency noise caused by shaking when moving the touch ben, and output coordinate detection signal 0. ．． 07' is appropriately determined so as to be smoothed well. Also, since the output pen amplifier/down signal oi' is used as a read timing signal for the output coordinate detection signals o, , o,', the integration time constant τ of the integrating circuit 6 is
1 is also set large. This integral time constant τ is appropriately determined so as to correspond to the maximum expected chattering interval. <Problems to be Solved by the Invention> However, if the integration time constant is set to a large value, the following new problems arise. (i) Integration time constant τ2 of the integration circuit 8.9. Since τ is set large, the input coordinate detection signal 08. as shown in FIG. 6(a). When a sudden level change occurs in Ol, it cannot be followed up well, and a significant response delay (time TI) occurs in the output coordinate detection signals O, o,'. As a result, the coordinate data indicated by the output coordinate detection signals o,, o,' no longer match the coordinate position currently being touched by the touch ben. (ii) Output coordinate detection signal o, , for chattering
Even though the integral time constants τ,, τ, are set large in order to smooth the input coordinate detection signal 0.o,', the chattering continues for a long time as shown in FIG. ．． 0. As the total time for the output coordinate detection signal 080,' to reach the 10" level increases, the level of the output coordinate detection signal 080,' gradually decreases and deviates from the normal level. Therefore, as above, the detection coordinate data and the current coordinate position of the touch ben are (1i) Because the integration time constant τ of the integration circuit 6 is set to a large value, the rise of the integration output (see broken line) is slow when the touch pen is down, as shown in Figure 6 (C). , it takes a long time to reach the reference level Vrefo set in the comparator circuit 7 and to start outputting the output pen up/down signal OL.Due to this response delay (time T8), if the touch pen is moved immediately after it is down, In this case, the detected coordinate data and the current coordinate data of the touch pen do not match as described above.The present invention has been made in view of these circumstances, and the present invention has been made in view of the above circumstances. It is also an object of the present invention to improve responsiveness and prevent false detection. That is, the coordinate detecting device of the present invention includes a first integrating circuit that integrates an input pen up/down signal from a pressure-sensitive tablet, and an integrated output of the first integrating circuit that is set to a value that eliminates chattering. A first comparator circuit that outputs a pen up/down signal when the level is equal to or higher than a reference level, and a small integration time constant that integrates and outputs the input X-direction coordinate detection signal from the pressure-sensitive tablef. A coordinate detecting device comprising a second integrating circuit and a third integrating circuit having a small integration time constant that integrates and outputs an input y-direction coordinate detection signal from the pressure-sensitive tablet.
a fourth integral pen up/down signal from the pressure sensitive tablet having an integral rise time constant greater than the integral time constant of the integrator circuit and an integral fall time constant set to substantially zero; and this fourth integration circuit.
As a reference level for the integral output of the integrating circuit, a reference level is determined such that the integral output is passed after the output X-direction coordinate detection signal and the output Y-direction coordinate detection signal have completed rising and become stable; A second comparison circuit compares the integrated output with the reference level and outputs a read timing signal for the output X-direction coordinate detection signal and the output y-direction coordinate detection signal when the integrated output is equal to or higher than the reference level. It is something to do. Effects> The effects of the above configuration of the present invention are as follows. The output pen up/down signal from the first comparison circuit is
It is used only as a signal to identify whether the touch pen is powered up or down for pressure-sensitive tablets, and is not used as a read timing signal. The read timing signal for the output X-direction coordinate detection signal and the output y-direction coordinate detection signal is provided by the fourth integration circuit and the second integration circuit.
is generated by the comparison circuit of The integration rise time constant of the fourth integration circuit is the same as that of the second integration circuit. The reference level of the second comparison circuit is set to be larger than the integration time constant of the third integration circuit, and the reference level of the second comparison circuit is set to the integration output of the fourth integration circuit after the output X-direction coordinate detection signal and the output y-direction coordinate detection signal have completed rising. Load Thailand

[It is specified that the signal must be passed as a signaling signal.] Therefore, when this read timing signal is output, the re-output coordinate detection signal has already completed its rise and is in a stable state, whether it rises due to the touch pen being down or due to chattering. Furthermore, since the integration fall time constant of the fourth integration circuit is set to substantially zero, when the re-output coordinate detection signal falls due to chattering, the read timing signal disappears at the moment when the fall starts. There is. As described above, the read timing signal is generated only during the period when both output coordinate horizontal output signals are stable, so even if the output coordinate detection signal is affected by chattering, the read timing signal will not be generated based on the read timing signal. The read output coordinate detection signal does not include the influence of chattering. And from this, the second point. The output coordinate detection signal from the third integrating circuit may be influenced by chattering, and as a result, the second. This means that the integration time constant of the third integration circuit may be made sufficiently small. <Example> Hereinafter, an example of the present invention will be described in detail based on the drawings. FIG. 1 is a block diagram showing the main parts of the coordinate detection device of the embodiment. A first integrator circuit 10 is connected to the output terminal of the pen up/down signal Oi of the pressure-sensitive tablef A shown in FIG. 3, and a first comparison circuit 11 is connected to the output terminal of this integrator circuit 10. An output pen up/down signal 05' is taken out from the output terminal of this comparison circuit 11. In addition, the X-direction coordinate detection signal O of pressure-sensitive tablef) A
A second integrating circuit 12 is connected to the output terminal of O8, and an output X-direction coordinate detection signal O8 is output from the output terminal of this integrating circuit 12.
' is extracted. Similarly, the output terminal of the y-direction coordinate detection signal O7 of
An integrating circuit 13 is connected, and an output y-direction coordinate detection signal O7f is taken out from the output terminal of this integrating circuit 13. The above configuration is the same as the conventional example. However, the integration time constants τ1, τ2τ,' of each of the integrating circuits 10, 12, and 13 are set to be sufficiently smaller than in the conventional example. That is, τ1 τ1, τ2 τg, τ3τ,
and τ,′−τ,′. The feature of this embodiment is that a fourth integrating circuit 14 is connected to the output terminal of the pen up/down signal 01 of the pressure-sensitive tablet A, and a second comparing circuit 15 is connected to the output terminal of this integrating circuit 14. The comparator circuit 15 is connected so that the read timing signal OA is output from the comparator circuit 15. The fourth integration circuit 14 has different integration time constants at rise and fall, and the integration rise time constant τ4 is different from the second. Integration time constant τ of the third integration circuit 12.13, τ
2', and the integral falling time constant τ
, is effectively set to zero. That is, τ4〉
τF'-τ3 and τS are 0. Incidentally, although the integral rise time constant τ4 is larger than τ2, τ]', it is larger than τ8. of the conventional example. This is a sufficiently small time constant compared to τ. Each of the above signals 〇5, 0. ．． 0. ．． The output terminal 0a' is connected to a microcomputer (not shown). Next, the operation of the coordinate detection device of this embodiment will be explained based on the time chart of FIG. Assume that at time t, the touch pen is placed down on pressure-sensitive tablet A. Then, due to the voltage e0 generated across the voltage detection resistor R3, the input pen up/down signal 01 shown in FIG. At the same time, the human power X-direction coordinate detection signal 0.4 from the differential amplifier 5°4 shown in FIGS.
The input y-direction coordinate detection signal O2 rises sharply at the same time t0, and is input to the second integration circuit 12 and the third integration circuit 13, respectively. The human pen up/down signal O1 in figure (a) is
), the first integration circuit 10 integrates with the integration time constant τ1' and gradually increases, and when the integrated output reaches the reference level V ref + of the first comparison circuit 11, the first The output of the comparator circuit 11 becomes "H0 level. This is the output pen amplifier/down signal Q,/ shown in Figure (C). This pen amplifier/down signal 0./ is used only to detect the up/down of the touch pen. used,
Unlike the conventional example, it is not used as a read timing signal. The input pen up/down signal Oi in figure (a) is
As shown in FIG. d), the fourth integration circuit 14 integrates the signal with the integration rise time constant τ and gradually increases, and reaches the reference level Vrefz of the second comparison circuit 15 at time 1.
At this point, the output of the second comparator circuit 15 becomes "H" level. This is the read timing signal OA shown in figure (e).
It is. This read timing signal O, is shown in figure (g).
, (i) to determine the reading timing of the output X-direction coordinate detection signal 08 and the output y-direction coordinate detection signal ○,'. The human power X-direction coordinate detection signal 01 shown in FIG.
' is integrated and becomes the output X-direction coordinate detection signal 08',
Input y-direction coordinate detection signal 0 in figure (h). are the integration time constants τ,
' is integrated and becomes the output y-direction coordinate detection signal O7'. What should be noted here is the second. Third integration circuit 12.
13 integration time constants τ2, τ,' are the fourth integration circuit 14
is smaller than the integral rise time constant τ4 of (τ 1−
τ3' - τ4), time t when the integrated output of the fourth integrating circuit 14 reaches the reference level Vreh and the read timing signal OA rises! , the output X-direction coordinate detection signal O
8. The time t1 at which the output y-direction coordinate detection signal OV' completes rising and starts stabilizing is earlier. In other words, the reading of the output coordinate detection signals 08, ○, ' is based on the output coordinate detection signals 0. ．． This means that it is to be carried out after 0° has stabilized. If the touch pen is moved while touching the pressure-sensitive tablet A, chattering will occur due to shaking or the like. Assuming that the occurrence of chattering starts from time t3, the input pen up/down signal 01 in Figure (a) is set to ``0''.
The state of Rubel appears. Due to this chattering, the integrated output of the first integrating circuit 10 shown in FIG. The output pen amplifier/down signal OI' maintains the 'H level. That is, despite the occurrence of chattering, the output pen up/down signal O% eliminates the chattering noise. In contrast, the input pen up/from time t4
The transition of the down signal OL to the "L" level is due to the raising of the touch pen, and at this time, the integral output of the first integrating circuit 10 becomes lower than the reference level Vref+, as shown in Fig. (c).
) output pen up/down signal O1' is inverted to °L" level. In other words, the microcomputer monitors only the up/down of the touch pen by the output pen up/down signal 0.', and determines whether chattering occurs or not. Not monitored. Now, return to the stage at time t3 and continue the explanation. When a state of "0" level appears in the human-powered pen amplifier/down signal Oi in Figure <8) due to chattering, the fourth integrating circuit 14 In other words, since the integral fall time constant τ is almost zero, the integral output in Figure (d) falls sharply. Therefore, Figure (e) output from the second comparator circuit 15 ) read timing signal 0^ also falls sharply at the same time t. Input coordinate detection signal 01lO shown in Figures (f) and (h)
A also fell sharply at the same time t due to chattering, and the second. The figure (
g), output coordinate detection signals oIl, o shown in (i)
, ' also fall to the "0" level in the case of the 0 example in which they fall relatively quickly because their integral time constants τ, , τ8 are relatively small. However, at the stage where the output coordinate one-meal output signals a,,o,' are falling, the read timing signal OA in Figure <e> has already been at the "0" level at the previous time t. Output coordinate detection signal o, which is in the middle of falling
o,' are not read.The output coordinate detection signals o,,o,' are read by the read timing signal OA only when the output coordinate detection signals o,,o,' are stable. . As a result, since the integration time constant τ, , τ,′ is small, even if the output coordinate detection signal 0, , ○,′ is affected by chattering, this effect is eliminated and there is no risk of false detection. Second. Third integration circuit 12.
The integral time constant τ2τ,′ of 13 may be sufficiently small,
Output coordinate detection signals a,,o,' when the touch pen is down
It is possible to have a sharp rise with very good responsiveness, and the input coordinate detection signal 0.0. ．． 0. It is possible to quickly follow sudden level changes. Second. The third integrating circuit 12.13 exclusively uses the input coordinate detection signal 0. ．． 0. This is provided to prevent overshoot and high frequency noise from occurring at the rise and fall of the signal. In the conventional example, since the output pen amplifier/down signal 01 was used as a read timing signal, the output coordinate detection signal 01IO2' was affected by chattering during the period when the output pen up/down signal OL' was "H". Therefore, the integration time constant τ of the integration circuit 7.8 had to be made sufficiently large, and as a result, the response and tracking performance were reduced. Note that due to chattering at time ′Rt, the figure (
Even though the read timing signal OA in e) has been inverted to the 6L'' level, the output pen amplifier/down signal O1' in Figure (c) maintains the °H'' level. It can be determined that the reversal of the signal OA to the "L" level is not due to the touch pen being raised, but due to chattering. <Effects of the Invention> According to the present invention, the following effects are achieved. The fourth integration circuit and the second comparison circuit allow the second and third
Output X-direction coordinate detection signal and output y from the integrating circuit of
Since the read timing signal is generated only during the period when the direction coordinate detection signal is stable, even if the output coordinate detection signal includes the influence of chattering, the output coordinate detection signal can be read with this influence removed. It is possible to prevent false detection. In addition, if the chattering continues for a long time, the output coordinate detection signal becomes 1.
Even if the total time at the 0'' level becomes longer, the influence of chattering has been eliminated as described above, so the level of the output coordinate detection signal that has been read will be the same as the normal level, and the accurate coordinates will be determined. Position detection can be performed.Since the output coordinate detection signal may include interference due to chattering, the integration time constants of the second and third integration circuits can be made sufficiently small. It is possible to quickly follow sudden changes in the coordinate detection signal and rises during touch down.

[Brief explanation of drawings]

1 and 2 relate to an embodiment of the present invention, in which FIG. 1 is a block diagram of a coordinate detection device, and FIG. 2 is a time chart for explaining the operation. FIG. 3 is a schematic diagram of the pressure-sensitive tablet common to the embodiment and the conventional example, and FIG. 4 is an output waveform diagram of the pressure-sensitive tablet during normal operation and chattering. 5 and 6 relate to the conventional example;
The figure is a block diagram of the coordinate detection device, and FIG. 6 is a waveform diagram for pointing out problems.

Claims (1)

[Claims] (1) A first integrating circuit that integrates an input pen up/down signal from a pressure-sensitive tablet, and compares its integrated output with a reference level determined as a value for eliminating chattering, and when the integrated output is equal to or higher than the reference level. a first comparison circuit that outputs a pen up/down signal; a second integration circuit with a small integration time constant that integrates and outputs an input x-direction coordinate detection signal from the pressure-sensitive tablet; a third integrating circuit with a small integration time constant that integrates and outputs an input y-direction coordinate detection signal, wherein a fourth integrator circuit having a time constant and an integral fall time constant set to substantially zero, the fourth integrator circuit integrating an input pen up/down signal from the pressure sensitive tablet; As a reference level for the integral output, a reference level is set such that the integral output is passed after the output x-direction coordinate detection signal and the output y-direction coordinate detection signal have completed rising and become stable, and the integral output is A coordinate detection device comprising: a second comparison circuit that outputs a read timing signal for the output x-direction coordinate detection signal and the output y-direction coordinate detection signal when the output x-direction coordinate detection signal and the output y-direction coordinate detection signal are equal to or higher than the reference level. .