JPH0119177B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coordinate detection device for detecting the position of a pen, cursor, or the like having an excitation coil on a tablet on which conducting wires for detection are arranged.

In general, a coordinate detection device consists of a stylus pen or cursor with an excitation coil attached to its tip, a tablet on which a detection lead wire is arranged on which the tip of the stylus pen or cursor is placed, and a detection lead wire connected to the tablet by the excitation coil. and a detection section that detects the coordinates of the stylus pen or cursor based on the generated signal.

1 and 3 show the arrangement of conductive wires belonging to the X-axis base arranged on the insulating plate or sheet of the tablet. Reference numeral 1 denotes first conductive wires (hereinafter referred to as cos wires), which are arranged at regular intervals in a meandering manner with a pitch p. Reference numeral 2 denotes a second conducting wire (hereinafter referred to as a sine wire), which is arranged at equal intervals in a meandering manner at the same pitch p as the cosine wire 1, but is shifted by 1/4 pitch from the cosine wire 1. a ₁ and a ₂ are both terminals of the cos wire 1, and a ₂ and a ₂ are both terminals of the sine wire 2. on the other hand,
In Fig. 3, 3 is the third conductor wire (hereinafter referred to as the selector wire), which is arranged in a comb-like shape at equal intervals, whereas the cosine wire 1 and sine wire 2 are arranged in a meandering pattern. . The number and spacing of the comb teeth of the selector wire 3 can be selected as appropriate, but as an example,
They can also be arranged at the same spacing as the pitch p of the cosine lines 1 and sine lines 2. A ₃₁ to _{a 36} are terminals at the end of each comb tooth of the selector wire 3. 4 represents an excitation coil attached to the tip of the stylus pen or cursor.
The excitation coil 4 is supplied with a sinusoidal current of a predetermined amplitude and frequency.

FIGS. 2a and 2b and FIG. 4 show the induced voltage V generated in the cosine line 1, sine line 2, and selector line 3 with respect to the position X where the excitation coil 4 is placed. cos line 1 and
Induced voltage generated in sin line 2 (curves A _{1 and 2} , respectively)
Indicated by A ₂ . ) are shifted from each other by π/2.
Therefore, the position of the excitation coil 4 within the pitch p can be detected by the combination of the induced voltages of the cosine line 1 and the sine line 2. On the other hand, a high voltage (shown by curve A ₃ ) is induced in the selector wire 3 only between the comb teeth where the excitation coil 4 is present. Therefore, by sequentially checking the voltage between each terminal a ₃₁ to _{a 36} of the selector wire 3, it is possible to detect which pitch the excitation coil 4 is placed at. As a result, the pitch number is detected from the voltage induced in the selector wire 3, and the position within the pitch is detected from the voltage induced in the cosine wire 1 and the sine wire 2. Therefore, the X-axis coordinate of the stylus pen or cursor can be detected.

The Y-axis base is configured identically to the X-axis base and is arranged at right angles thereto, and the Y-axis coordinate is detected by the same means.

The above-mentioned coordinate detection device is
Since it is described in Publication No. 34855, detailed explanation will be omitted.

FIG. 5 is a block diagram showing a schematic configuration of a conventional coordinate detection device. Reference numeral 4 denotes an excitation coil shown in FIGS. 1 and 3, which is composed of a coil L including a resistor R. 5 is a tablet consisting of an X-axis base having a cosine line 1, a sine line 2, and a selector line 3, and a Y base. E ₁ , E ₂ , E ₃ are the terminals of cos wire 1, respectively.
This is an induced voltage generated between a ₁ and a ₁ , between terminals a ₂ and a ₂ of the sine wire 2, and between two terminals of the terminals a ₃₁ to a ₃₆ of the selector wire 3. Reference numeral 6 denotes a detection unit that calculates the voltages E ₁ , E ₂ , and E ₃ to detect the coordinates of the exciting coil 4 . 7 is a sine wave generating circuit for generating a sine wave voltage to be applied to the excitation coil 4; 8 is an amplifier for amplifying the sine wave voltage generated by the sine wave generating circuit 7.

A sine wave voltage of a predetermined frequency generated by the sine wave generating circuit 7 is converted into a sine wave of a predetermined amplitude by an amplifier 8 and is supplied to the exciting coil 4 . When this excitation coil 4 is placed on the tablet 5, as mentioned above,
Voltages E 1 , E 2 , and E 3 are induced in the cosine line ₁ , the sine line ₂ , and the selector line ₃ according to their positions. This voltage is taken out from each terminal a ₁ , a ₂ , a ₃₁ to a ₃₆ and sent to the detection unit 6.
The X and Y coordinates of the excitation coil 4 are thereby detected.

In such a conventional coordinate detection device, the current supplied to the excitation coil 4 by the amplifier 8 is always constant. On the other hand, the voltage induced in each conducting wire by the excitation coil 4 is equal in the cosine wire 1 and the sine wire 2 (E ₁ = E ₂ ), but the induced voltage in the selector wire 3 is equal to the voltage E ₁ due to the wiring. , E ₂ (E ₁ , E ₂ < E ₃ ). For this reason, when detecting the selector line 3 in the detection section 6, the gain of the detection circuit is lowered so that the signal levels are the same. As described above, in the configuration in which the current supplied to the excitation coil 4 is constant, considerable heat is generated in the excitation coil 4. Furthermore, as for the usage of the coordinate detection device, for example, the cos line 1, the sine line 2, the selector line 3 If it is necessary to arrange the excitation coil at a considerable distance from the surface of the tablet (therefore, the excitation coil and each conductor are quite far apart), at least
In order to induce a predetermined voltage in the cosine wire 1 and the sine wire 2, the current supplied to the excitation coil 4 must be increased, and this increase in current has the disadvantage that the excitation coil 4 generates more heat. It was hot.

SUMMARY OF THE INVENTION An object of the present invention is to provide a coordinate detection device that eliminates the above-mentioned conventional drawbacks and can suppress the amount of heat generated by the excitation coil to a low level.

To achieve this objective, the present invention combines the cos
The present invention is characterized in that the value of the current supplied to the excitation coil is converted depending on the detection of the induced voltage generated in the sine wire and the detection of the induced voltage generated in the selector wire.

Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 6 is a block diagram showing a schematic configuration of a coordinate detection device according to an embodiment of the present invention. In the figure, the fifth
Components that are the same as those shown in the figures are given the same reference numerals and explanations will be omitted.

9 is a switching device interposed between the sine wave generation circuit 7 and the amplifier 8; r is a variable resistor connected to the sine wave generation circuit 7; A is a terminal connected to the sine wave generation circuit 7; B is a terminal connected to variable resistor r, and C is a terminal connected to amplifier 8. 1
0 is a switching piece that is connected to terminal C and switches between terminals A and B. Although the switching device 9 is normally composed of an electronic switching element, it will be shown as a mechanical structure to make the explanation easier to understand. e ₁ and e ₂ are detection mode signals from the detection section 6, and the switching piece 10 is switched to either terminal A or terminal B by these detection mode signals e ₁ and e ₂ .

Next, the operation of this embodiment will be explained with reference to FIG.

When the excitation coil 4 is placed at a certain position on the tablet 5, induced voltages E ₁ , E ₂ and E 3 are generated in the cosine wire 1, sine wire 2 and selector wire ₃ as described above.
The detection unit 6 sequentially takes in the voltages E ₁ , E ₂ , and E ₃ as data, performs necessary calculations and controls, and detects the coordinates of the exciting coil 4 . The voltages E ₁ , E ₂ , E ₃
In order to take in the wires in order, the detection unit 6 has terminals for each wire.
A switching unit is provided which is connected to a ₁ , a ₂ , a ₃₁ to a ₃₆ , and the switching unit performs a switching operation in response to a switching signal from the data processing unit in the detection unit 6 to change the voltages E ₁ , E ₂ ,
E ₃ is gradually being introduced. Now, such switching signals will be used as detection mode signals e ₁ and e ₂ for switching the switching pieces 10 of the switching device 9.

When the detecting section 6 receives the voltage of the cosine line 1 or the sine line ₂ (period T1 in FIG. 7), the detecting section 6 outputs the detection mode signal _e1 , and the switching piece 10 is connected to the terminal A.
Connect to the side. Therefore, the sine wave output from the sine wave generating circuit 7 is directly input to the amplifier 8, and a sine wave voltage with the same peak value _V1 as in the past is applied to the excitation coil 4, and a current corresponding to this is applied. flows. Next, when the detection section 6 takes in the voltage of the selector line 3 (period T ₂ in FIG. 7), the detection mode signal e ₂ is output from the detection section 6, and the switching piece 10 is connected to the terminal B side. . Therefore, the sine wave output from the sine wave generating circuit 7 is input to the amplifier 8 via the adjusted resistor r, so that the excitation coil 4 receives a sine wave voltage with a lower peak value V ₂ than before. is applied, and a corresponding current flows. By the way, as mentioned above, the voltage E ₃ induced in the selector line 3
is larger than the voltages E ₁ and E ₂ , so even if the current supplied to the exciting coil 4 becomes small in the selector detection mode (period T ₂ ), there is no problem in detecting it. By appropriately selecting the gain of the detection circuit of the detection unit 6,
It can be kept constant when detecting either the line 2 or the selector line 3. This is the excitation coil 4
When viewed from the side, in the selector detection mode, the supply current decreases, so the current of the excitation coil 4 as a whole decreases, and the amount of heat generated also decreases. Furthermore, if the switching is performed at the zero point of the sine wave current, no transient phenomenon will occur.

In this way, in this embodiment, the magnitude of the sine wave input to the amplifier is switched when detecting the cosine line, the sine line, and the selector line.
The current in the excitation coil can be reduced to suppress its heat generation, and it is also possible to deal with an increase in the current to the excitation coil when the excitation coil is used apart from each conductor.

FIG. 8 is a block diagram showing a schematic configuration of a coordinate detection device according to another embodiment of the present invention. In the figure, parts that are the same as those shown in FIG. 5 are given the same reference numerals, and explanations thereof will be omitted.

Reference numeral 11 denotes a ring counter which sequentially repeats and outputs a predetermined numerical value by inputting a clock pulse.
12 is a ROM (read only memory) in which a predetermined value is stored in a predetermined location, and a ring counter 1
Depending on the numerical value output from 1, the numerical value stored at the address corresponding to this numerical value is read out. 13
is the numerical value (digital value) read from ROM12
This is a D/A converter that converts the data into analog values. Each numerical value of the ring counter 11 and ROM 12 is D/
The output of the A converter 13 is set to have step-like waveforms g ₁ and g ₂ shown in FIG. 9. That is, in FIG. 9, the voltage V is plotted on the vertical axis and the time t is plotted on the horizontal axis, but the horizontal axis can also be expressed as an address. For example, when the numerical value from the ring counter 11 is n, the ROM 12 This means that a digital value that becomes V _o when converted to an analog value is stored at address n. 14 is a filter circuit that converts the stepped output from the D/A converter 13 into a gentle sine waveform. Filter circuit 14
The sine wave output of is applied to the excitation coil 4 via an amplifier 8. e ₃ and e ₄ are detection mode signals corresponding to the detection mode signals e ₁ and e ₂ in the previous embodiment, and these detection mode signals e ₃ and e ₄ are composed of digital value signals, for example, two conductive wires. is input to the ROM12.

Next, the operation of this embodiment will be explained with reference to FIG.

When the excitation coil 4 is placed at a certain position on the tablet 5, voltages E ₁ , E 2 and E 3 are generated in the cosine line 1, the sine line ₂ and the selector line ₃ . As described in the description of the previous embodiment, the voltages E ₁ , E ₂ , and E ₃ are sequentially taken in in the detection section 6 by the switching signal. This switching signal is used as detection mode signals e ₃ and e ₄ .

When the detection unit 6 receives the voltage of the cosine line 1 or the sine line 2, the detection unit 6 outputs a detection mode signal e ₃ (for example, “00”). On the other hand, a certain value (for example, "1010") is also output from the ring counter 11, and this value is used together with the value of the detection mode signal _e3 .
A numerical value (for example, "101000") designating a predetermined address of the ROM 12 is configured. The numerical value stored at the address corresponding to this numerical value is read from the ROM 12 and converted into an analog value by the D/A converter 13. A new value (for example, ``101100'') is given to the ROM 12 by the next value from the ring counter 11 (for example, ``1011''), and the new value stored there is read out from the address corresponding to this value. An analog value corresponding to the value is output from the D/A converter 13. In this way, the stepwise waveform _g1 shown in FIG. 9 is sequentially output. This output is smoothed by the filter 14 and output from the amplifier 8 during the period T ₁ of FIG.
The same sine wave as in is output. Next, when the detection section 6 receives the voltage of the selector line 3, the detection section 6 outputs a detection mode signal e ₄ (for example, "11"). On the other hand, ring counter 11
From then on, the same combination of numerical values is repeated regardless of the detection mode signal, but since the detection mode signal has been switched from signal e ₃ to signal e ₄ , the cos
This results in a different numerical value than in the case of detecting line 1 and sin line 2 (for example, a signal with a numerical value of "101000" for mode signal e ₃ becomes a numerical value of "101011" for mode signal e ₄ ). , therefore, the designated address of the ROM 12 is also a different address. In this way,
The numbers are different from those in the case of detecting cosine line 1 and sine line 2.
It is output from the ROM 12 and converted into an analog value by the D/A converter 13. In this way, the stepwise waveform _g2 shown in FIG. 9 is sequentially output from the D/A converter 13. Since waveform g ₂ is selected to be smaller than waveform g ₁ at each step (that is, so that the value of the ROM 12 read at the same time is smaller than for waveform g ₁ ),
The sine wave output from the amplifier 8 via the filter 14 becomes smaller and becomes the same sine wave as the sine wave in period _T2 in FIG.

In this way, in this example as well, sine and cosine
Since the same sine wave voltage as in the previous embodiment is applied to the excitation coil when detecting the line and when detecting the selector line, the same effect as in the previous embodiment is achieved.

Note that in each of the above embodiments, cosine, sin
We have only explained the cases when detecting wires and selector wires, but at times other than when detecting cosine wires, sinus wires, and selector wires, the input to the excitation coil is set to 0 using the detection mode signal. In this way, the excitation coil current can be further reduced. Moreover, although the case where the switching signal in the detection section is used as the detection mode signal is illustrated, other appropriate signals in the detection section can also be used.

As described above, in the present invention, the current value supplied to the excitation device is changed depending on the detection of the voltage induced in the cosine line and the sine line, and the detection of the voltage induced in the selector line. The amount of heat generated by the device can be suppressed to a low level, and it is possible to cope with an increase in current when the excitation device is used separated from each conductor.

[Brief explanation of drawings]

Figure 1 is an arrangement diagram of cos and sine lines, Figure 2 a and b are waveform diagrams showing changes in voltage induced in the cos and sine lines of Figure 1 with respect to position, and Figure 3 is the arrangement of selector lines. 4 is a waveform diagram showing changes in the voltage induced in the selector line of FIG. 3 with respect to position, FIG. 5 is a block diagram showing a schematic configuration of a conventional coordinate detection device, and FIG. Seventh block diagram showing the schematic configuration of the coordinate detection device according to the embodiment
6 is a waveform diagram of the voltage applied to the excitation coil shown in FIG. 6, FIG. 8 is a block diagram showing a schematic configuration of a coordinate detection device according to another embodiment of the present invention, and FIG.
This figure is a waveform diagram of the output voltage of the A/D converter shown in FIG. 8. 1...cos wire, 2...sin wire, 3...selector wire, 4...excitation coil, 5...tablet, 6...
...Detection unit, 7...Sine wave generation circuit, 9...Switching device, 11...Ring counter, 12...ROM,
13...D/A converter, 14...filter.

Claims (1)

[Claims] 1 A first conductor wire arranged at a predetermined pitch, a second conductor wire arranged at the same pitch as the first conductor wire and shifted by 1/4 pitch, and the first conductor wire and the second conductor wire arranged at a predetermined pitch.
an X-axis base and a Y-axis base having a third conductive wire arranged at a predetermined position with respect to the conductive wire; and an excitation device that generates a signal to the first conductive wire, the second conductive wire, and the third conductive wire. , a coordinate detection device comprising: a detection unit that detects the position of the excitation device based on the signals generated in each of the conductive wires; A coordinate position detection device characterized by comprising means for changing a current value supplied to the excitation device depending on the time of signal detection.