JPH0665928U - Stylus pen and tablet for coordinate position input device - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the S / N ratio of the received signal of the coordinate input device. [Structure] The tip portion of the stylus pen pen shaft is made of conductive resin, and the bearing for holding the pen shaft is made of a small synthetic resin having a dielectric constant of 2.1 or less at 1 MHz. This suppresses signal attenuation on the pen axis and improves electrostatic coupling with the X and Y electrodes of the tablet. ITO is used for the X and Y electrodes of the tablet,
By selecting the area resistance to be 10 to 25 Ω / cm ² , while maintaining the transmittance of 85% or more, and when the size of the tablet is the same as the conventional one, the reception frequency is considerably higher than the conventional one, 1 MHz or (For example, 1.
It is possible to set it to 8 MHz), and external noise having a relatively low frequency and a large level can be easily cut by the filter of the coordinate input device.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a stylus pen and a tablet of a coordinate position input device, and more particularly to improvement of signal attenuation.

[0002]

[Prior art]

 FIG. 3 is a block diagram of a coordinate position input device proposed mainly for the purpose of making a stylus pen cordless before obtaining the present invention. Reference numeral 1 indicates a carrier signal transmitting means, and 2 indicates a receiving means. The signal transmission pen (stylus pen) 11 includes a carrier wave oscillator 12, an oscillation control circuit 13, an activation switch 14, a battery voltage detection circuit 15 and a battery 16, and the outer cylinder of the pen 11 is connected to a battery reference electrode. . The tip of the pen 11 is electrically insulated from the outer cylinder.

The tablet 21 has a plurality of X electrodes (X _{1 to} X _m ) and Y electrodes (Y _{1 to} Y _n ) arranged similarly to a conventional tablet, and is connected to the X and Y electrode selectors 22 and 23, respectively. To be done. For scanning the X electrodes and the Y electrodes, input signals (start signals) STX and STY, a shift clock signal CLK, and a clear signal CLR are given from the tablet controller 41 to the X and Y shift registers 24 and 25, respectively. The output of the Y shift register controls switching of the X and Y electrode selectors 22 and 23, respectively. A time series signal of the received signal of each X or Y electrode is obtained from the X and Y electrode switching devices 22 and 23. This signal is amplified by the amplitude unit 27 to an appropriate size, only the carrier wave of the pen 11 is taken out by the band pass filter 28, and the position signal is taken out by the absolute value detector 29.

A staircase-shaped position signal is input to a filter (active filter module) 30 to remove high frequency components, and then input to a comparator 31 to generate a stop signal STP and input to a tablet controller 41, where a coordinate position is calculated. Data DX and DY are obtained. Next, the pen operation will be described. When the tip of the pen comes in contact with the tablet 21, the pen pressure moves due to this contact pressure, the start switch 14 is turned on, and the oscillation control circuit 13 such as a Schmitt circuit is activated. When the output of the oscillation control circuit 13 and the signal of the battery voltage detector 14 that detects the battery voltage and raises the signal if the battery voltage is higher than the reference value are applied to the carrier wave oscillator 12, the oscillator 12 is started, A carrier wave is applied to the tip of the pen tip. By using the signal of the battery voltage detector 15, it is possible to display the battery replacement time by a light emitting diode or the like.

Next, a detailed description will be given with reference to signal waveforms. The carrier wave signal transmitted from the pen 11 is received by the X and Y electrodes (FIG. 3A), but the reception level varies depending on the distance from the pen position. The X, Y start signals STX, STY and the shift clock CLK are given to the X, Y shift registers 24, 25 from the tablet controller 41, and the X or Y electrode switching signal (FIG. 3B) is generated to successively output the X, Y electrodes. The received signals of the electrodes are given to the switches 22 and 23 and are sequentially collected in time series to obtain a stepwise received signal (FIG. 3C). After amplifying this signal by the amplifier 26, the carrier is selected by the bandpass filter 28, noise is removed (FIG. 3D), and the absolute value detector 29 detects it (FIG. 3E).

This signal is input to an active filter module (a bandpass filter or a lowpass filter having a center frequency of about 5 kHz) 30, high-frequency components are cut, and the stylus pen shifts below the pitch of the X or Y electrodes. An output signal with sinusoidal peaks with corresponding phase shifts is obtained (Fig. 3F). The stop signal S TP is input to the comparator (module) 31 to detect the phase of this filter output signal, and falls when an input of the threshold voltage V _th or more comes and rises at the zero crossing point of the input (Fig. 3G) is obtained and given to the tablet controller 41.

A coordinate counter is built in the tablet controller 41, and the coordinate counter that started counting at a certain time is stopped at the first rising edge of the STP signal, and X and Y coordinate data DX and DY are obtained from the count value. , Is input to the CPU. FIG. 5 shows a sectional view of the stylus pen 11, and FIG. 6 shows a sectional view and an exploded perspective view of the tablet 21. The X and Y electrodes are made of a transparent ITO film. An oscillation control circuit 13, a carrier wave oscillator 12, a battery voltage detector 15 and the like are mounted on the substrate 1a of the stylen pen 11. The output of the carrier wave oscillator 12 is propagated to the moving shaft 1k made of metal through the coil spring 1h and the metal chuck 1f, and the chip 1d made of an insulating material such as synthetic resin and the glass plate of the tablet 21 are made into a dielectric material. Is transmitted through the electrostatic capacitance formed between the moving shaft 1k and the X or Y electrode and received by each electrode.

FIG. 7 shows the change in signal level with respect to the distance in the longitudinal direction of each electrode of the conventionally proposed tablet 21. As can be seen from the figure, the signal level decreases with the distance between the electrodes and also with the signal frequency. When the length of the electrode is 240 mm, it is difficult to increase the carrying frequency above 1 MHz from the viewpoint of signal attenuation.

[0009]

[Problems to be solved by the device]

 The conventionally proposed stylus pen in FIG. 5 has a large signal propagation loss in the Ben shaft 1c and a poor electrostatic coupling property with the electrode of the tablet. As a result, the S / N ratio on the receiving side using the tablet is reduced. There was a problem of decline. In addition to the stylus pen transmission signal, each electrode of the tablet receives a relatively large frequency of external noise in the environment in which the tablet input device is located, which is relatively low. Therefore, it is difficult to obtain highly reliable coordinate position data with a poor S / N ratio even through the BPF 28.

In order to eliminate the above-mentioned drawbacks, if the carrier frequency of the pen is increased and noise is easily attenuated by the BPF 28, the sheet resistance of the transparent electrode of the tablet and the capacitance between the upper glass pattern and the lower glass pattern cause the noise. Limited by carrier frequency. Immediately, when an attempt is made to receive a high frequency carrier wave using a conventional glass tablet, the attenuation due to the distance in the longitudinal direction of the electrode is remarkable as shown in FIG. 7, and the size of the usable tablet becomes small. Therefore, it was difficult to set the carrier frequency above 1 MHz.

A first object of the present invention is to improve the signal propagation loss in the pen shaft of the stylus pen and to improve the electrostatic coupling with the tablet electrode to improve the S / N ratio of the received signal. Especially. The second purpose is to make the length of the X and Y electrodes of the tablet and the size of the X and Y electrodes, and hence the size of the tablet, smaller than that of the conventional one by reducing the degree of the signal level decrease with the increase of the carrier frequency. Without lowering the carrier frequency, the carrier frequency is selected to be larger than the conventional one to facilitate separation from external noise by the filter, improve the S / N ratio, and obtain highly reliable coordinate position data. is there.

[0012]

[Means for Solving the Problems]

 (1) As a measure to improve the S / N ratio, it is no problem if the received signal of each electrode is set higher than the noise level by about 30 dB. Therefore, it is a matter of course to increase the output of the carrier oscillator as much as possible. A conductive plastic is used to improve the electrostatic coupling with the tablet electrode. Moreover, by using an insulator bearing with a small dielectric constant between the pen outer cylinder and the pen shaft, we aim to improve the signal propagation loss in the pen shaft.

Further, by selecting the carrier frequency as high as about 1 MHz or higher, it becomes easy to suppress external noise having a relatively low frequency and a large level by the filter on the receiving side using the tablet, and the S / N ratio is increased. To improve. (2) By increasing the sheet resistance value (also called area resistance value) of each electrode of the tablet to R = 10 to 25 Ω / cm ² , increase the length of the electrode while ensuring the transmittance of 85% or more. Both the decrease in signal level due to and the decrease in signal level due to increase in carrier frequency are made smaller than before, and the carrier frequency is made higher than before without making the tablet size smaller than before, and the external noise due to the filter is eliminated. Separation is facilitated, S / N is improved, and highly reliable coordinate position data is obtained.

[0014]

【Example】

 FIG. 2 is a structural example of the stylus pen 11 according to the present invention. Reference numeral 1a is a substrate in which the oscillation control circuit 13, the carrier wave oscillator 12, and the battery voltage detector 15 shown in FIG. Reference numeral 14 is a start-up switch whose lead terminal 14a is soldered to a pin 1b provided on the substrate 1a. Reference numeral 16 denotes a battery, which accommodates two button types in the figure. Reference numeral 1f is a chuck that transmits a signal to the tip 1d of the pen tip and can be slightly actuated in the axial direction by the writing pressure of the pen, electrically insulates from the outer cylinder 1e, and easily tip 1d (pen shaft 1c). A sliding bearing 1g is provided. The chip 1d is pressed into the chuck 1f made of an elastic metal material. A coil spring 1h is provided on the outer peripheral surface of the semi-cylindrical chuck 1f and is electrically connected to the chuck 1f.

The other end of the coil spring 1h is covered with an insulating tube and is soldered to the substrate 1a. A member 1f 'for operating the starting switch 14 is attached to the other end of the chuck 1f. The shape and function of the member 1f 'may be changed according to the type of the starting switch 14. For example, if the activation switch 14 is a switch such as a photo interrupter, it may have a shape capable of blocking light. The coil spring 1h has not only the function of transmitting a signal but also the function of returning the movement of the pen shaft 1c due to the writing pressure.

In the figure, the negative electrode of the battery is in contact with the outer cylinder 1e made of a metal material to shield the entire pen, and the negative electrode is connected to the substrate 1a from the outer cylinder 1e through the coil spring 1i. Further, the positive electrode voltage is supplied to the substrate 1a through the positive electrode current collecting coil spring 1j, and at the same time, when excessive writing pressure is applied, it is absorbed by the coil spring 1j to protect intermediate members. Conventionally, an insulating resin is used for the tip 1d of the stylus pen tip for the sake of writing. In the present invention, a conductive resin such as a carbon fiber-containing polyacetal resin is used as the chip 1d. Although the detection signal of the tablet plate is larger when the tip 1d is thick and the tip is flat, it is not possible to make it too thick for practical use, and it is better that the tip is spherical rather than flat in view of writing and the like. The tip 1d is press-fitted into the semi-hollow portion of the chuck 1f, which is made of a cylindrical semi-hollow metal, but the tip 1d may be integrally formed of the same material as the tip 1d up to the chuck 1f.

Conventionally, polyacetal resin (POM) is used as the bearing 1g, and its mechanical characteristics are good, but since the permittivity is as large as 3 to 4 at 1 MHz, it is between the pen shaft 1c and the outer cylinder 1e. Since the formed capacitance becomes large and the carrier wave leaks to the outer cylinder, the propagation loss of the signal on the pen shaft was large. Therefore, in the present invention, by using, for example, a fluororesin (trade name: Teflon) for the bearing 1g, its dielectric constant is reduced to about 2.1 at 1 MHz, and the electrostatic capacitance is about half that of the conventional one. Therefore, the propagation loss on the pen axis is improved.

Next, the tablet will be described. The ITO film is a transparent electrode material with excellent conductivity. It has chemical and thermal stability that can withstand practical use, and because it has good electrode pattern processability, it is often used in segment display and dot matrix display. It is used as a transparent electrode for liquid crystal displays. The ITO film is a crystalline transparent film produced by vapor deposition, sputtering, pyrolysis spray, etc., and has a wide range of resistance from high resistance (200 Ω / cm ² or more) to low resistance (10 Ω / cm ² ). This is the film used.

When the film resistivity is ρ [Ω · cm], the sheet resistance (area resistance) is R [Ω / cm ² ] and the film thickness is d [Å], ρ = R · d × 10 ⁻⁸ I have a relationship. FIG. 1A shows the relationship between the sheet resistance R and the film thickness d. When the resistivity ρ of ITO is 2.0 × 10 ⁻⁴ Ω · cm, the film thickness d = 200 Å is about 100 Ω / cm ² , the 670 Å is about 30 Ω / cm ² , and the 2,000 Å is about 10 Ω / cm ² . It becomes a value. FIG. 1A also shows the relationship between the film thickness d and the transmittance.

FIG. 1B shows the relationship between the transmittance of the ITO film and the sheet resistance R at a wavelength of 550 [nm]. From FIG. 1B, the sheet resistance R at which a transmittance of 85% or more is obtained is 70 Ω / cm. ² Above and 10 to 25 Ω / cm²There are two resistance ranges. In the past, the former range was used, but in the present invention, by selecting the latter range, it is possible to reduce the signal level in the electrode length direction and the signal level due to an increase in the carrier frequency. I was able to reduce it considerably. FIG. 1C shows a signal attenuation characteristic with respect to the distance in the longitudinal direction of the electrode of the tablet using the low resistance film of the present invention. At a distance of 240 mm, a signal of 1.8 MHz is attenuated by only 85%, which means that it can be practically used as a tablet. Further, the decrease in the signal level due to the increase in the signal frequency is also significantly reduced as apparent from the comparison with the conventional example of FIG. Therefore, in this invention, the signal frequency (the carrier frequency of the stylus pen) is selected to be 1 MHz or higher, for example, 1.8 MHz, so that the BPF 28 of the coordinate position input device can easily remove the external noise having a relatively low frequency and a large level. You can

[0021]

[Effect of device]

(1) In the stylus pen of the present invention, since the tip portion of the tip of the pen shaft is made of conductive resin, the effective distance between the pen shaft and the X and Y electrodes of the tablet is shortened, and the coupling capacitance is reduced. , And signal propagation loss is reduced. (2) In the stylus pen of the present invention, when the bearing for the pen shaft is made of a resin having a small dielectric constant, the distribution capacity between the pen shaft and the outer cylinder, which is generated by the bearing, is significantly reduced. Signal propagation loss on the shaft is reduced. Therefore, it contributes to the improvement of the S / N ratio on the signal receiving side using the tablet together with the item (1). (3) In the tablet of this invention, the ITO film forming the X and Y electrodes is selected to have the sheet resistance R 10 of 10 to 25 Ω / cm ² , so that the transmittance of 85% or more can be secured and the length of the electrode can be increased. Directional distance and the decrease in signal level due to the increase in frequency are much smaller than before, so if the size of the tablet is the same as before, the signal frequency will be 1 MHz or more, for example 1.8 MHz Higher selection is possible. Therefore, a filter on the receiving side using a tablet can easily cut off external noise having a relatively low frequency and a large level, and the S / N ratio can be greatly improved. (4) As described above, according to the stylus pen and the tablet of the present invention, the S / N ratio on the signal receiving side of the input device is greatly improved, so that highly reliable coordinate position data can be obtained.

[Brief description of drawings]

FIG. 1A is a diagram showing the relationship between the ITO film thickness d and the transmittance or sheet resistance R, B is a diagram showing the relationship between the sheet resistance R and the transmittance of ITO, and C is the tablet X or Y of the present invention. The figure which shows the attenuation | damping characteristic of the signal with respect to the distance of the longitudinal direction of an electrode.

FIG. 2 is a sectional view showing an embodiment of a stylus pen of the present invention.

FIG. 3 is a block diagram of a coordinate position input device proposed at a stage before obtaining the present invention.

FIG. 4 is an operation waveform diagram of a main part of FIG.

5 is a cross-sectional view showing an example of the structure of the stylus pen 11 of FIG.

6A and 6B are a sectional view and an exploded perspective view showing the structure of the tablet 21 of FIG. 3, respectively.

7 is a diagram showing signal attenuation characteristics with respect to the longitudinal distance of the X or Y electrode of the tablet of FIG.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Creator Takayuki Hashi, 1387 Tobuki-cho, Hachioji-shi, Tokyo Tokyo Cosmos Electric Co., Ltd.

Claims (4)

[Scope of utility model registration request] 1. A stylus pen for a coordinate position input device, which transmits an output of a built-in carrier wave oscillator, wherein a tip portion of a tip of the pen shaft is made of a conductive resin. Stylus pen. 2. The stylus pen for a coordinate position input device according to claim 1, wherein a bearing attached to the tip of the pen outer cylinder and movably holding the pen shaft is 1 MHz.
Is characterized by being composed of a synthetic resin having a dielectric constant of about 2.1 or less. 3. The stylus pen for a coordinate position input device according to claim 1 or 2, wherein the oscillation frequency of the carrier wave oscillator is selected to be approximately 1 MHz or higher. 4. A plurality of electrodes parallel to the X axis are formed on the inner surface of the first glass plate at substantially the same pitch, and a plurality of electrodes parallel to the Y axis are formed on the inner surface of the second glass plate at substantially the same pitch. In a tablet for a coordinate position input device, which is formed by integrally bonding the inner surfaces of the first and second glass plates with an insulating film interposed therebetween, the electrodes are formed of ITO, and the sheet resistance thereof is 1
A tablet for a coordinate position input device, which is selected from 0 to 25 Ω / cm ² .