JPH065496B2 - Ultrasonic application tablet - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ultrasonic application tablet for handwriting information input by a computer or the like.

[Background of the Invention]

Conventionally, in a writing device of an elastic wave application tablet used as a handwriting input device, one of the problems is the variation of the orientation position due to the inclination angle of the input pen. In particular, in the case of the method of performing the orientation using the propagation time of the elastic wave, the phase angle changes depending on the inclination angle of the input pen, which is essentially an unavoidable problem.

Hitherto, a writing device using a surface wave among elastic waves has been proposed which has a layered structure. For example, in Japanese Unexamined Patent Publication No. 50-50830, a contact type position encoder using surface acoustic waves has a structure having a second sheet under a first sheet for transmitting surface waves. Since the purpose is to attenuate the bulk wave, a material with a large bulk wave attenuation factor is used. As described above, regarding the writing plate combined for other purposes, the consideration of the material necessary for eliminating the influence of the inclination of the input pen as proposed in the present invention is not taken into consideration.

[Object of the Invention]

The object of the present invention is to enable coordinate detection by ordinary handwriting input, and to reduce the waveform change of the detected wave caused by the incident angle of the ultrasonic wave from the input pen or the rotation angle of the input pen, and in particular the phase inversion. An object is to provide an ultrasonic application tablet that can achieve higher accuracy by preventing it.

[Outline of Invention]

The principle of the longitudinal wave method according to the present invention and the problem of pen tilt will be described.

FIG. 1 shows the configuration of an ultrasonic application tablet using longitudinal waves. The writing unit includes an input pen 1 and a writing device 2. The writing device 2 comprises a writing plate 3 and wave receivers 4 (a, b, c, d) installed at respective corners thereof. The input pen 1 includes a transmitter 1a, a pen tip 1b,
It is composed of a grip 1c, a pulse voltage is applied by a pulse excitation circuit 5, and a longitudinal ultrasonic wave is emitted from the pen tip 1b of the input pen 1. The longitudinal ultrasonic wave incident on the writing plate 2 propagates through the writing plate 3 and the wave receiver 4 (a
~ D), and input to the waveform shaping circuit 6. The output of the waveform shaping 6 is input to the time counting circuit 7, and the propagation time from the ultrasonic wave incident point to each wave receiver is measured.
The output of the time counting circuit 7 is input to the coordinate calculating circuit 8 to perform position locating calculation, and then the locating result is displayed on the display device 9.
Is displayed at.

FIG. 2 shows a situation in which the longitudinal ultrasonic wave input to the waveform shaping circuit 6 changes depending on the inclination angle of the input pen 1. This figure shows waveforms detected by both wave receivers when the wave pen A and B are installed at both ends of the writing plate 3 and a longitudinal ultrasonic wave is incident from the intermediate point P by the input pen 1. FIG. 3A shows a detection waveform when the input pen 1 is vertically placed, and the first arrival wave F is detected by the receivers A and B in the same phase. On the other hand, (b), (c) and (d) of the same figure show detected waveforms when the input pen 1 is gradually inclined toward the wave receiver A side. The first arriving wave F at the wave receiver B has a slight level change, but no phase change is observed, whereas the first arriving wave F at the wave receiver A changes in phase with a change in level and has a slope. In (d) with a large angle, the phase is inverted. Therefore, when measuring the propagation time focusing on the first arrival wave F,
For example, when focusing on the peak point, the propagation time varies depending on the inclination angle θ, which causes a localization error.

The phenomenon in which the waveform of the detected wave changes when the pen is tilted is because the component of the ultrasonic wave incident on the medium 10 parallel to the medium surface is affected by the tilt of the input pen. Proved by simulation analysis. The results are shown in FIG. When the input pen 1 is perpendicular to the medium surface as shown in FIG. 3 (a), it can be seen that the phase of the wave spreading in the medium is symmetric with respect to the pen. However, when the input pen 1 is tilted as shown in FIG. 3 (b), the wave phase is reversed in a region near the surface of the medium 10 on the tilted side of the pen,
It can be seen that the phase is asymmetrical about the pen. Further, when analyzed in detail, the region in which the phase is reversed expands as the inclination of the input pen increases. From these, it can be seen that the inclination of the input pen 1, that is, the component of the ultrasonic wave incident on the medium 10 parallel to the medium surface directly affects the phase of the wave component parallel to the medium surface in the medium. . Due to this phenomenon, the waveform of the detected wave changes when the pen tilts.

However, if you look carefully, you can see that not all phases on the tilted side of the pen are reversed.
That is, the wave phase is symmetric with respect to the pen at a position deep below the surface of the medium where the ultrasonic waves are incident, particularly below the depth at which the vortex of the arrow representing the wave phase is generated. Therefore, if the wave having the symmetric phase can be guided to the detecting element earlier than the asymmetric wave, the influence of the inclination of the pen can be reduced, and the waveform change of the detected wave, especially the phase inversion can be prevented.

Example of Invention

The present invention was born from the idea described above, and an embodiment thereof is shown in FIG. In the writing device 2, the writing plate 3 has a structure including at least two layers, and a longitudinal wave velocity (a propagation velocity of a longitudinal wave component of ultrasonic waves) on the propagation layer medium 3a for propagating ultrasonic waves from the propagation layer medium. 2), the input layer medium 3b made of a slow material is provided, and the wave receiver 4 (a, b, c, d) is attached to the propagation layer medium 3a side.

FIG. 5 is a diagram in which the effect of the present invention is confirmed by simulation. The materials used in this analysis are shown in Table 1. From FIG. 5, it is proved that the idea of the present invention is correct when the medium is made into two layers and a region in which the phase is made symmetrical is formed even when the pen is tilted. Furthermore, the in-phase region in which this phase is symmetrized by detailed analysis becomes larger as the input layer with slower sound waves becomes thicker when the inclination of the pen is constant, and when the input layer is constant, the in-phase region becomes larger. The smaller the slope of, the larger the in-phase region, but
The length of the in-phase region in the direction parallel to the surface of the writing plate 3 is
It has been found that when the length becomes about half the wavelength of the ultrasonic wave transmitted through the propagation layer medium 3a, the in-phase region does not increase thereafter even if the input layer is thickened. That is, if one wavelength of the wave is explained with the waveform of FIG. 2, it is like a peak portion and a valley portion of the waveform, and with the arrow of FIG.
This is because the components having opposite phases, such as the rightward component and the leftward component, are composed of approximately half of the wavelength, and one component does not become longer than half.

Therefore, the fact that the length of the in-phase region is about half the wavelength of the ultrasonic wave transmitted through the propagation layer medium 3a means that the phase reversal due to the inclination of the input pen 1 is almost completely prevented. It means that you can.

From this, it is understood that the thickness of the input layer medium 3b does not need to be excessively thick. It was also found that by slowing the sound wave in the input layer, the thickness of the layer for achieving the same effect can be reduced.

From a practical point of view, if the length of the in-phase region in which the phase is made symmetric is half the wavelength of the ultrasonic wave transmitted through the propagation layer medium 3a at the time of the maximum practical pen inclination, the ultrasonic wave is actually ultrasonic wave. Input pen 1 when using an application tablet
The orientation position will not change due to the inclination of.

Therefore, in practice, when the maximum possible pen tilt angle is set, the length of the in-phase region is half the wavelength of the ultrasonic wave in the propagation layer medium 3a, so that the ultrasonic propagation velocity is low. The material and thickness of the layer medium 3b are determined. Specifically, when the ultrasonic frequency is 400 kHz and the material of Table 1 is used, if the maximum inclination of the input pen is 40 °, the thickness of the input layer may be 1.2 mm, and the maximum inclination is 30 °. It was found that the thickness of the input layer should be 0.8 mm if it exists.

By configuring the tablet as described above, it is possible to reduce the waveform fluctuation due to the inclination of the pen, and especially to prevent the phase inversion, and it is possible to realize an ultrasonic application tablet that can highly accurately evaluate the position.

The materials shown in Table 1 are transparent, and tablets made of such transparent materials can be used for liquid crystal display devices and CRTs.
If laminated on the display surface such as, there is an advantage that an ultrasonic application tablet in which the input surface and the display surface are integrated can be realized. There are many transparent materials having different longitudinal wave velocities, and combinations thereof are possible. Also, the same material, acoustically 2
The same effect can be obtained by using a layered material.

Although the above description has been made on the transparent writing plate, the same effect can be obtained with an opaque material. For example, aluminum (longitudinal wave velocity: 6260 m / s) is used as the propagation layer medium, and bakelite ((longitudinal wave velocity: 2590
By using m / s), the influence of the inclination of the pen can be eliminated.

Next, another embodiment will be described. FIG. 6 shows an application of the composite structure of the writing device. An intermediate layer medium 3c intermediate the propagation layer medium 3a and the input layer medium 3b of the writing plate 3 is provided, and the longitudinal wave velocity is the above-mentioned intermediate layer medium. It is characterized in that a medium having an intermediate speed between longitudinal wave velocities of the propagation layer medium and the input layer medium is used.

Next, the effect of this embodiment will be described.

In the embodiment shown in FIG. 4 described above, it is explained that the thickness of the input layer required to prevent the phase inversion due to the tilt of the pen can be reduced by using the material having the slow ultrasonic wave propagation velocity.

However, on the other hand, if there is an excessive difference between the propagation speed of the longitudinal wave component in the propagation layer medium 3a and the propagation speed of the longitudinal wave component in the input layer medium 3b, the propagation from the input layer medium 3b to the propagation layer medium 3a is increased. There is a problem that the transmissibility of ultrasonic waves is reduced.

Therefore, even if the propagation speed of the longitudinal wave component between the two types of media is too different and the transmissivity of the ultrasonic waves is low, the propagation speed of the longitudinal wave component between these media is By interposing an intermediate medium having an intermediate speed between the medium and the other medium, it is possible to suppress a decrease in the transmissibility of ultrasonic waves.

Therefore, in the embodiment of FIG. 6, the intermediate layer medium 3c is provided. Therefore, according to this embodiment, the transmissivity of ultrasonic waves can be kept high, and as a result, as shown in FIG. It is possible to increase the level of the signal detected by the wave receiver 4 shown.

Therefore, the embodiment shown in FIG. 6 has an effect that ultrasonic waves can be sufficiently detected even if the size of the writing plate 3 is large, and a large tablet can be easily dealt with.

Also, FIG. 7 differs from the above-described two embodiments in that the input pen is improved. As shown in the enlarged view of the same figure,
A contact piece 11 is provided at the tip of the pen tip 1b of the input pen 1, and a material having a longitudinal wave velocity lower than that of the writing plate 3 is used as the contact piece material. In this case, as the material of the pen tip 1b, it is preferable to use a material having a longitudinal wave velocity higher than that of the contact piece. As described above, this embodiment is effectively the same as the case of FIG. 4, and the influence of the inclination of the input pen can be eliminated.

As a method of manufacturing the above-mentioned composite writing plate, there is a method of bonding a plurality of plates having different sound speeds, for example, a plywood method of bonding a polycarbonate plate or an acrylic plate on a glass plate. As another method, there is a manufacturing method in which the two-layered medium is made in the same material in terms of acoustic characteristics by using the physical properties of the material in the manufacturing process, for example, the difference in specific gravity.

EFFECTS OF THE INVENTION According to the present invention, in the ultrasonic application tablet, the waveform change of the detection plate caused by the inclination of the pen can be reduced, and in particular, the phase inversion can be prevented, so that the tablet with high accuracy can be obtained. Further, compared to a tablet that corrects a waveform change using a special detector or an additional circuit, it is possible to obtain an effect that it can be easily configured.

[Brief description of drawings]

FIG. 1 is a block diagram showing the principle of an ultrasonic application tablet using longitudinal waves, FIG. 2 is a waveform state detected by a wave receiver when the input pen is tilted, and FIG. 3 is a writing plate from the input pen. Simulation result of ultrasonic wave behavior incident on the inside, FIG. 4 is an example showing a composite writing device according to the present invention, FIG.
FIG. 6 is a simulation result showing the effect of compounding, and FIG. 6 is another embodiment of the compounding writing device according to the present invention.
FIG. 7 shows another embodiment according to the present invention in which the input pen side is improved. DESCRIPTION OF SYMBOLS 1 ... Input pen, 2 ... Writing device, 3 ... Writing board, 4 ... Receiving element, 5 ... Pulse excitation circuit, 6 ... Waveform shaping circuit, 7 ... Time counting circuit, 8 ... Coordinate operation circuit, 9 ... Display device.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masanori Tanabe 4026 Kuji Town, Hitachi City, Hitachi, Ibaraki Prefecture Hitachi Research Laboratory, Ltd. (72) Hiroko Kawakami 4026 Kuji Town, Hitachi City, Ibaraki Prefecture Hitachi, Ltd. In Hitachi, Ltd. (72) Inventor Shigeru Inose, 800, Tomita, Ohira-cho, Shimotsuga-gun, Tochigi Hitachi, Ltd., Tochigi factory (72) Inventor, Norio No. 800, Tomita, Ohira-cho, Shimotsuga, Tochigi Hitachi, Ltd., Tochigi factory (72) Inventor Hideo Fukuhashi 800 Tomita, Ohira-machi, Shimotsuga-gun, Tochigi Prefecture Tochigi Plant, Hitachi Ltd. (56) Reference JP-A-63-103317 (JP, A)

Claims (3)

[Claims] 1. A transmitter that is excited by an electric signal to generate ultrasonic waves, an input pen having a pen tip that radiates the ultrasonic waves from one point, and a writing plate that propagates the ultrasonic waves from the input pen. A writing device, which is provided at an end portion of the writing plate and includes a wave receiver that converts propagated ultrasonic waves into an electric signal,
In an ultrasonic application tablet consisting of a signal processing device which locates the position of the input pen from the detection signal of the writing device and displays it on a display device, a writing plate of the writing device is a propagation layer medium for propagating ultrasonic waves. , And at least two layers of an input layer medium provided thereon, wherein the propagation velocity of the longitudinal wave component of the ultrasonic wave in the input layer medium is the longitudinal wave of the ultrasonic wave in the propagation layer medium. An ultrasonic application tablet characterized in that the wave receiver is attached to the medium of the propagation layer using a material made of a material having a velocity slower than the propagation velocity of the component. 2. In the ultrasonic application tablet according to the structure of the first aspect, the propagation velocity of the longitudinal wave component of the ultrasonic wave in the propagation layer medium constituting the writing plate and the input layer medium is An intermediate layer medium made of a material having an intermediate velocity between the propagation velocity of the longitudinal wave component of the ultrasonic wave in the propagation layer medium and the propagation velocity of the longitudinal wave component of the ultrasonic wave in the input layer medium is provided. An ultrasonic application tablet characterized by being used. 3. An input pen provided with a wave transmitter excited by an electric signal to generate an ultrasonic wave, a pen tip for emitting the ultrasonic wave, a writing plate for propagating the ultrasonic wave from the input pen, and the writing. A writing device, which is provided at an end of the plate and includes a wave receiver that converts propagated ultrasonic waves into an electric signal, and a signal processing device that locates the position of the input pen from a detection signal of the writing device and displays the position on a display device. In the ultrasonic application tablet consisting of, when writing on the writing plate with the pen, a contact piece is provided so as to be located between the pen and the writing plate, and the contact piece As a characteristic of using a material made of a material in which the propagation velocity of the longitudinal wave component of the ultrasonic wave therein is slower than the propagation velocity of the longitudinal wave component of the ultrasonic wave in the propagation layer medium. And super Wave applications tablet.