JPH02116922A - Coordinate input device - Google Patents

Abstract

PURPOSE:To decrease the influence onto a vibration transfer caused by a supporting member by enlarging the surface roughness of at least a part of the contact surface to a vibration transfer plate of the supporting member of the vibration transfer plate. CONSTITUTION:Fine irregularity is worked on the supporting surface 71t of a supporting member 71 to a vibration transfer plate 8, and it is set to a state that the surface roughness is large. In such a way, the vibration transfer plate 8 does not adhere closely to the supporting surface 71t of the supporting member 71, and the influence exerted on the vibration transfer of the vibration transfer plate 8 by the supporting member 71 such as vibration of the vibration transfer plate 8 is absorbed by the supporting member 71, and an operation of a vibration waveform detecting system becomes unstable due to attenuation can be decreased.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention detects vibrations input from a coordinate input device, particularly a vibrating pen, using a plurality of sensors provided on a vibration transmitting plate, and transmits the vibrations of the photographing pen. This invention relates to a coordinate input device that detects coordinates on a board.

[Prior Art] Coordinate input devices using various types of input pens, tablets, etc. have been known as devices for inputting handwritten characters, figures, etc. to processing devices such as computers.

In this type of system, input image information consisting of characters, graphics, etc. is output to a display device such as a CRT display or a recording device such as a printer.

The following various methods are known for detecting the coordinates of a tablet in this type of device.

1) A method that detects changes in the resistance value of a sheet material placed opposite the resistive film.

2) A method that detects electromagnetic or electrostatic induction from conductive sheets placed opposite each other.

3) A method that detects ultrasonic vibrations transmitted from the input pen to the tablet.

In the above methods 1) and 2), it is difficult to form a transparent tablet because a resistive film or a conductive film is used. On the other hand, in method 3), the tablet can be constructed from a transparent material such as an acrylic plate or a glass plate, so the input tablet can be placed on top of a liquid crystal display, etc., and can be used as if it were writing an image on paper. A good coordinate input device can be constructed.

At the same time, even if an opaque tablet is used, the structure is very simple and there is no need to provide electrodes or the like on the tablet, so it is possible to provide an inexpensive tablet.

[Problems to be Solved by the Invention] While ultrasonic coordinate detection has superior advantages over other methods as described above, conventional ultrasonic coordinate input tablets have the following problems. there were.

With the ultrasonic method that uses surface acoustic waves, coordinate detection becomes impossible if there are propagation obstacles such as scratches on the tablet surface, so an ultrasonic method tablet that uses plate wave acoustic waves has been proposed.

By the way, in the case of plate wave elastic waves, the vibration does not occur on the front surface of the tablet, but rather on the entire plate body of the tablet, so the back surface of the tablet vibrates at the same time as the input surface of the tablet.

Therefore, if the member supporting the tablet that propagates the plate wave elastic wave is made of a material such as resin that relatively absorbs ultrasonic waves, the vibration will be greatly attenuated, making it impossible to stably input vibration to the vibration sensor. Accurate coordinate detection was not possible. Furthermore, under the same vibration input conditions, the effective transmission distance of vibrations also becomes smaller, resulting in the problem that the size of the input surface is limited.

An object of the present invention is to solve the above problems and to minimize the influence of the support member of the vibration transmission plate on vibration transmission.

[Means for Solving the Problems] In order to solve the above problems, in the present invention, vibrations input from a vibration vent are detected by a plurality of sensors provided on a vibration transmission plate, and the vibrations of the vibration vent are transmitted. In a coordinate input device that detects coordinates on a plate, a structure is adopted in which the surface roughness of at least a portion of the contact surface with the vibration transmission plate of a support member that supports the vibration transmission plate in a contact state is increased.

[Function] According to the above configuration, the contact area of the support member with the vibration transmission plate can be substantially reduced, and the influence of the support member on the vibration transmission of the vibration transmission plate can be reduced.

[Example] Hereinafter, the present invention will be described in detail based on the example shown in the drawings.

FIG. 1(a) shows the structure of a coordinate input device employing the present invention. The coordinate input device shown in FIG. 1(a) inputs coordinates to an input tablet consisting of a vibration transmission plate 8 using a vibrating ben 3.

In the figure, the reference numeral 8 is a vibration transmission plate made of acrylic, glass plate, etc., or other opaque materials such as resin or metal. Three vibration transmission plates are provided at the corners of the plate to transmit the vibration from the vibration ben 3. transmitted to the vibration sensor 6.

In this embodiment, the coordinates of the vibration ben 3 on the vibration transmission plate 8 are detected by measuring the transmission time of the ultrasonic vibration transmitted from the vibration ben 3 to the vibration sensor 6 via the vibration transmission plate 8.

The vibration transmission plate 8 is configured to prevent vibrations transmitted from the vibration vent 3 from being reflected at the periphery and returning toward the center.
Its peripheral portion is supported by an antireflection material 7 made of silicone rubber or the like.

As shown in the figure, the vibration sensor 6 is fixed at a predetermined position on the vibration transmission plate 8 by adhesion, pressure bonding, or the like. One electrode of the vibration sensor 6 is grounded, and an output signal is taken out from the other electrode and input to the waveform detection circuit 9.

The vibration ben 3 transmits ultrasonic vibration to the vibration transmission plate 8.
It has a vibrator 4 made of a piezoelectric element or the like inside, and transmits ultrasonic vibrations generated by the vibrator 4 to a vibration transmission plate 8 via a horn portion 5 having a sharp tip.

FIG. 2 shows the structure of the vibrating vent 3. A vibrator 4 built into the vibrator 3 is driven by a vibrator drive circuit 2. The driving wJ signal of the vibrator 4 is supplied as a low-level pulse signal from the arithmetic and control circuit 1 shown in FIG. , is applied to the vibrator 4.

The electrical drive signal is converted into mechanical ultrasonic vibration by the vibrator 4 and transmitted to the diaphragm 8 via the horn section 5.

The vibration frequency of the vibrator 4 is selected to a value that allows the vibration transmission plate 8 to generate plate waves. Further, when driving the vibrator, a vibration mode is selected in which the vibrator 4 mainly vibrates in the vertical direction in FIG. 2 with respect to the vibration transmission plate 8. Further, by setting the vibration frequency of the vibrator 4 to the resonance frequency of the vibrator 4, efficient vibration conversion is possible.

The elastic waves transmitted to the vibration transmission plate 8 as described above are plate waves, which have the advantage that they are less affected by scratches, obstacles, etc. on the surface of the vibration transmission plate 8 than surface waves.

FIG. 1(b) shows the structure of a support member that supports the vibration transmission plate 8 of the present invention, and FIG. 1(C) is a partially enlarged view thereof.

In FIG. 1(b), the vibration transmission plate 8 is supported by a support member 71. In FIG. The support member 71 is for guaranteeing the strength of the input surface made of the vibration transmission plate 8, which is thinly constructed so as to transmit vibration efficiently, and is made of a predetermined material such as resin, and the vibration transmission plate 8 is supported by the surface. The vibration sensor 6 is fixed at a predetermined position on the support member 71, and the detection surface of the vibration sensor 6 is brought into contact with the vibration transmission plate 8 by a pressure contact means such as a spring (not shown).

The support member 71 supports the vibration transmission plate 8 by its surface, but from a microscopic perspective, as shown in FIG. 1(C),
The support surface 71t of the vibration transmission plate 8 of the support member 71 is machined with fine irregularities, and the surface roughness is 6.3S (J
IS B 0601). As a result, the vibration transmission plate 8 does not come into close contact with the support member 71, and the vibration of the vibration transmission plate 8 is not absorbed by the support member 71, or the operation of the vibration waveform detection system described below becomes unstable due to attenuation. There is no. In particular, the above effect can be achieved even if the material of the support member 71 is a general ultrasonic absorbing material such as resin, or a material with acoustic impedance close to or equal to that of the vibration transmission plate 8.

Furthermore, the vibration transmission distance is not restricted by the vibration absorption of the support member 71, making it easy to set up an input surface with a large area.

Here, the reason why the above-mentioned surface roughness condition was set to 6.3S or more will be explained.

Table 1 Table 1 shows the experimental results of investigating the relationship between the vibration transmission characteristics of the contacting vibration transmission medium '#a' and the surface roughness of the vibration transmission medium. Here, the vibration transmission medium is not the vibration transmission plate and its supporting member, but the experimental results regarding vibration transmission between the vibrator 4 of the vibrating pen 3 and the horn portion 5 of the pen tip. This is the same phenomenon as in the case of a vibration transmission plate and its supporting member in that two members are in contact and vibration transmission occurs between them.

Here, two vibrating pens with poor vibration output characteristics and two vibrating pens with good vibration output characteristics are prepared, and the characteristics of the surface of the horn part 5 of the pen tip of these vibrating pens, that is, the maximum peak height, maximum each imposition, and measurement. Value Rx.

R,,R, were measured.

Here, the measured values RX, Ra, and R2 are as follows.

Rx: When the sampled part is sandwiched between two straight lines parallel to the average line of the part extracted by the standard length from the cross-sectional curve, these two
The distance between straight lines measured in the direction of the longitudinal magnification of the cross-sectional curve (
JIS B 0601).

Rt: Select the line that passes through the third peak from the highest and the line that passes through the bottom of the third valley from the highest among the straight lines that are parallel to the average line of the part extracted from the cross-sectional curve by the standard length, and connect these two lines. The distance between straight lines is measured in the direction of the vertical magnification of the cross-sectional curve.

R1: Pick out a part of measurement length 2 from the roughness curve in the direction of its center line, set the center line of this cut out part as the X axis, the direction of vertical magnification as the Y axis, and make the roughness curve y = f (x) When expressed as , the value of R1 is given by the following formula.

Furthermore, a vibrating pen with poor output characteristics is one in which input is performed at a predetermined point on the vibration transmission plate, and a detection voltage above a certain level cannot be obtained by a predetermined vibration sensor.

Specifically, for the tablet used in the experiment, a vibration sensor output voltage of 1.5 to 1.6μ is required for normal coordinate input. 3.4), we were able to obtain a voltage in this range, but the two defective vibrating pens (number 1.2) had an extreme voltage of about 0.8 to 1.0■, which is about half to 2/3 of that of a good pen. (lower output voltage) is not obtained.

As is clear from the measured values of the pressure contact surface of the pen tip of each vibrating pen in Table 1 with the vibrator of the horn, the more uneven the pressure contact surface is, the lower the signal strength obtained by the vibration sensor is.

The applicant also conducted a number of measurements on a vibrating pen (not shown), and found that the vibration transmission efficiency drops sharply at a surface roughness of around 6.3S. Of course, the driving conditions for each vibrating pen, the pressure contact conditions between the vibrator and the horn, etc. are the same for all pens, so even if you change the pressure contact conditions between the vibrator and the horn, the vibration will still occur beyond the above boundary value. It was the same that the transmission efficiency changed drastically.

As is clear from the above, the surface roughness of the contact surface between two contacting vibration transmission media is at least 6.3.
It can be seen that when the value is smaller than 3, the vibration transmission efficiency is good, and when the value is larger than 3, the efficiency is significantly reduced.

Therefore, as described above, by setting the surface roughness of the contact surface of the support member 71 with the vibration transmission plate 8 to be equal to or higher than the above value, the vibration transmission efficiency between the two is reduced, and the support member 71
It can prevent vibration absorption to the side.

Next, some modification examples regarding the structure of the support member 71 will be shown.

It goes without saying that the supporting member 71 may have patterns such as grains and grooves as long as the surface roughness is greater than 6.33.

Furthermore, FIG. 1(d) and FIG. 1(e) show the support member 7.
An example is shown in which the vibration transmission plate 8 is not supported on the entire surface of the plate 1.

First, in FIG. 1(d), the vibration transmission plate 8 is made of a transparent material,
A display 81 such as a liquid crystal is disposed below the support member 71, and the support member 71 has a recess for accommodating the display 81. With such a structure, the surface roughness of the peripheral portion of the support member 71 that contacts the vibration transmission plate 8 is 6.3.
It only needs to be larger than 3. This structure is more effective because the possibility that the vibration of the vibration transmission plate 8 is transmitted to the support member 71 is reduced. In FIG. 1(d), the display 81 is fixed to the support member 71 side by adhesive or the like, and is not in contact with the vibration transmission plate 8.
does not affect vibration transmission. However, if the display 81 also functions as a support member for the vibration transmission plate 8, the roughness of the contact surface of the display 81 with the vibration transmission plate 8 should be set to be the same as that of the support member 71 within a range that does not impair the display function. is possible.

Further, FIG. 1(e) shows a case where the vibration transmission plate 8 is partially supported by the convex portion 71a on the upper surface of the support member 71. The convex portion 71a in FIG. 1(e) can be considered to be an extremely rough surface finish of the support member 71 in FIG. 1(C), and this alone can affect the vibration transmission of the vibration transmission plate 8 of the support member 71. Although it can be made smaller, the contact portion of the support member 71 to the vibration transmission plate 8 is further reduced to 6.
A greater effect can be obtained by processing the surface to have a surface roughness greater than approximately 3S. In addition, Figure 1 (
In the structure of e), since the vibration transmission plate 8 is supported also in the central portion, there is an advantage that the rigidity of the input surface can be increased compared to the structure of FIG. 1(d).

Next, the vibration detection system and coordinate calculation system in the above configuration will be explained.

Referring again to FIG. 1(a), the vibration sensor 6 provided at the corner of the vibration transmission plate 8 is also constituted by a mechanical to electrical conversion element such as a piezoelectric element. The output signals of each of the three vibration sensors 6 are input to a waveform detection circuit 9, and the timing of vibration arrival at each sensor is detected by waveform detection processing described later.

This detection timing signal is input to the arithmetic control circuit 1.

The arithmetic control circuit 1 detects the vibration transmission time to each sensor based on the detection timing input from the waveform detection circuit, and further detects the coordinate input position of the vibrating pen 3 on the vibration transmission plate 8 from this vibration transmission time.

FIG. 3 shows the structure of the arithmetic control circuit 1 shown in FIG. 1(a). Here, the structure of the drive system of the vibrating pen 3 and the vibration detection system using the vibration sensor 6 are mainly shown.

The microcomputer 11 includes an internal counter, ROM, and RAM. The drive signal generation circuit 12
It outputs a drive pulse of a predetermined frequency to the vibrator drive circuit 2 shown in FIG. 2A, and is activated by the microcomputer 11 in synchronization with the coordinate calculation circuit.

The count value of the counter 13 is latched into the latch circuit 14 by the microcomputer 11.

On the other hand, the waveform detection circuit 9 outputs timing information of a detection signal for measuring vibration transmission time from the output of the vibration sensor 6 as described later. These timing information are input to the input ports 15, respectively.

The timing signal input from the waveform detection circuit 9 is input to the input port 15 and stored in the storage area corresponding to each vibration sensor 6 in the latch circuit 14, and the result is transmitted to the microcomputer 11.

That is, the vibration transmission time is expressed as a latch value of the output data of the counter 13, and coordinate calculation is performed using this vibration transmission time value. At this time, the determination circuit 16 determines whether all waveform detection timing information from the plurality of vibration sensors 6 has been input, and
Notify 1.

FIG. 4 explains the detected waveform input to the waveform detection circuit 9 of FIG. 1(a) and the measurement process of vibration transmission time based on the detected waveform. In FIG. 4, reference numeral 41 indicates a drive signal pulse applied to the vibrating pen 3. Ultrasonic vibrations transmitted from the vibrating pen 3 driven by such a waveform to the vibration transmission plate 8 pass through the vibration transmission plate 8 and are detected by the vibration sensor 6.

After traveling within the vibration transmission plate 8 for a time tg corresponding to the distance to the vibration sensor 6, the vibration reaches the vibration sensor 6. Reference numeral 42 in FIG. 4 indicates a signal waveform detected by the vibration sensor 6. The plate wave used in this embodiment is a dispersive wave, so the envelope 42 of the detected waveform
The relationship between 1 and phase 422 changes depending on the vibration transmission distance.

Here, the speed at which the envelope advances is assumed to be group velocity Vg, and the phase velocity is assumed to be Vp. The distance between the vibrating pen 3 and the vibration sensor 6 can be detected from the difference in group velocity and phase velocity.

First, if we focus only on the envelope 421, its speed is g, and when a point on a certain waveform, for example a peak, is detected as indicated by reference numeral 43 in FIG. The distance 1111id is d = Vg - tg, where the vibration transmission time is tg.
...(1) This equation relates to one of the vibration sensors 6, but the same equation applies to the other two vibration sensors 6.
can indicate the distance of the vibrating pen 3.

Furthermore, in order to determine coordinate values with higher precision, processing based on phase signal detection is performed. Phase waveform 4 in Figure 4
22 specific detection points, for example, if tp is the time from vibration application to the zero cross point after passing the peak, then the distance between the vibration sensor and the vibration pen is d=n1λp+Vp l tp ee・(
2). Here, λp is the wavelength of the elastic wave, and n is an integer.

From the above equations (1) and (2), the above integer n is n= [
(Vg-tg-Vp-tp)/λp+1/N] ・
...(3) is shown. Here, N is a real number other than O, and an appropriate value is used. For example, if N=2 and the fluctuation of the group delay time tg is within ±1/2 wavelength, n can be determined.

By substituting n obtained as described above into equation (2), the distance between the vibration vent 3 and the vibration sensor 6 can be accurately measured.

In order to measure the two vibration transmission times tg and tp shown in FIG. 4, the waveform detection circuit 9 can be configured as shown in FIG. 5, for example.

In FIG. 5, the output signal of the vibration sensor 6 is amplified to a predetermined level by the amplification circuit 51 described above.

The amplified signal is input to the envelope detection circuit 52, and only the envelope of the detection signal is extracted. The timing of the peak of the extracted envelope is detected by the envelope peak detection circuit 53. From the peak detection signal, an envelope delay time detection signal Tg having a predetermined waveform is formed by a signal detection circuit 54 composed of a mono-multivibrator or the like, and is input to the arithmetic control circuit 1.

Further, a phase delay time detection signal "rp is formed by the detection circuit 58 from this Tg flaw signal timing and the original signal delayed by the delay time adjustment circuit 57, and is inputted to the arithmetic control circuit 1.

That is, the Tg flaw signal is converted into a pulse of a predetermined width by the monostable multivibrator 55. Further, the comparator level supply circuit 56 outputs t according to this pulse timing.
Form a threshold for detecting the p signal. As a result, the comparator level supply circuit 56 is connected to the reference numeral 44 in FIG.
A signal 44 having a level and timing as follows is generated and input to the detection circuit 58.

That is, the monostable multivibrator 55 and the comparator level supply circuit 56 are used to ensure that the phase delay time measurement is activated only for a certain period of time after the envelope peak is detected.

This signal is sent to a detection circuit 5 consisting of a comparator etc.
8 and is compared with the delayed detection waveform as shown in FIG.

The circuit shown above is for one vibration sensor 6, and the same circuit is provided for each of the other sensors.

If the number of sensors is generalized to h, then h detection signals of envelope delay times Tgl to h and phase delay times Tpl to h are input to the arithmetic and control circuit 1, respectively.

In the arithmetic control circuit of FIG. 3, the above 1g1~h, Tp1~
The h signal is input from the input port 15, and the count value of the counter 13 is taken into the latch circuit 14 using each timing as a trigger. As described above, since the counter 13 is started in synchronization with the driving of the vibration ben, the latch circuit 14 receives data indicating the respective delay times of the envelope and the phase.

When three vibration sensors 6 are arranged at the positions S1 to S3 at the corners of the vibration transmission plate 8 as shown in FIG. The straight line distance 1 mfdl to d3 to the position of the imaging sensor 6 can be determined.

Furthermore, the arithmetic and control circuit 1 can determine the coordinates (X Sy) of the position P of the vibrating vent 3 based on the linear distances d1 to d3 using the following formula using the 3-square theorem.

x=X/2+(d1+d2)(d1-d2)
/2X...(4) y=Y/2+(d1+d3)(d1-d3)
/ 2Y...(5) Here, X, Y are the X, Y of the vibration sensor 6 at the positions S2 and S3 and the sensor at the origin (position St)! lI [is the distance along h.

As described above, the position coordinates of the vibrating ben 3 can be detected in real time.

[Effects of the Invention] As is clear from the above, according to the present invention, vibrations input from a vibrating pen are detected by a plurality of sensors provided on a vibration transmission plate, and vibrations inputted from a vibrating pen are detected by a plurality of sensors provided on the vibration transmission plate. In a coordinate input device that detects coordinates, a structure is adopted in which the surface roughness of at least a portion of the contact surface with the vibration transmission plate of the support member that supports the vibration transmission plate in a contact state is increased, so that the surface roughness of the support member is increased. The contact area with the vibration transmission plate can be substantially reduced, and the influence of the support member on the vibration transmission of the vibration transmission plate can be reduced, so there is no reduction in coordinate input accuracy or vibration transmission distance due to vibration damping of the support member. Without,
This has the excellent effect of allowing stable and accurate coordinate input.

[Brief explanation of drawings]

FIG. 1(a) is an explanatory diagram showing the configuration of a coordinate input device employing the present invention, FIGS. 1(b) and (C) are sectional views showing the support structure of a vibration transmission plate according to the present invention, Figure 1 (d), (
e) is a sectional view showing different support structures of the transmission plate support member, Fig. 2 is an explanatory view showing the structure of the vibrating pen in Fig. 1(a), and Fig. 3 is a cross-sectional view showing the structure of the vibrating pen in Fig. 1(a). A block diagram showing the structure of the arithmetic control circuit, Fig. 4 is a waveform diagram showing detected waveforms to explain distance measurement between the vibrating pen and the vibration sensor, and Fig. 5 is the waveform detection circuit of Fig. 1 (a). FIG. 6 is an explanatory diagram showing the arrangement of vibration sensors. 1... Arithmetic control circuit 3... Vibration pen 4... Vibrator 6... Vibration sensor 8... Vibration transmission plate
51...Preamplifier 15.16...Input boat 52...Envelope detection circuit 54.58...Signal detection circuit 59...A/D conversion circuit 71...Support member Fig. 1 ( b) Sai ■ Kaimur (wa η and ear i op 1 shi examination, iic fig. 1 (C) 1000 y η i Cl gloss μ 之 (and 14 geo error get tσ')
Discontinuation i [ffi Figure 1 (d) 8 years old 1blr) a! m 6 contact action C 吋) shield meeting hii yun shang off z talent JY main negative summoning inner red hook stop 11E
Figure 1 (e) Shows a macroscopic pupil of 1 degree. Specified in Part 6 of Disbursement

Claims (1)

[Claims] 1) In a coordinate input device that detects the coordinates of the vibration pen on the vibration transmission plate by detecting the vibration input from the vibration pen using a plurality of sensors provided on the vibration transmission plate, the vibration transmission plate is in contact with the coordinate input device. A coordinate input device characterized in that the surface roughness of at least a portion of a contact surface of a support member that contacts a vibration transmission plate is increased.