JPH02110618A - Coordinate input device - Google Patents

Abstract

PURPOSE:To prevent the interference of vibration, and to detect a correct coordinate by providing a supporting member which is in contact directly with a vibration transmission plate through a surface and supports the vibration transmission plate, and setting the vibration transmission speed of the supporting member slower than the vibration transmission speed of the vibration transmission plate. CONSTITUTION:The vibration transmission plate 8 is made of glass, and the supporting member 30 is made of the material of acrylic resin, etc. When the vibration is impressed upon a point A on the vibration transmission plate 8 from a vibration pen 3, the state of the vibration becomes like 2A. Besides, when the vibration passes through the member 30, the vibration like 2B is excited. On the assumption that the head of the inputted vibration of the transmission plate 8 reaches the point C after certain time elapses, the state of the vibration becomes as shown by 2C. If the speed of the transmission in the transmission plate 8 of a wave propagating in the member 30 is slow, it becomes like 2E. Thus, by making the transmission speed in the member 30 slower than the transmission speed in the transmission plate 8, waveform to be detected at the point C is never influenced even if the transmission plate 8 is arranged, and the distortion of a signal to be detected by a vibration sensor can be made smaller, and correct vibration detecting timing can be obtained.

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. The present invention relates to a coordinate input device that detects coordinates on the top.

[Prior Art] Coordinate input devices using various input pens, tablets, etc. have been known as devices for inputting handwritten characters, figures, etc. to a processing device such as a computer. In this type of system, input image information consisting of characters, figures, etc. is output to a display lid 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) Electromagnetic or static electricity such as conductive sheets placed opposite each other 3
A method for detecting conduction.

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

[Problems to be Solved by the Invention] However, the conventional device as described above has the following drawbacks.

In other words, in the above-mentioned resistive film type, the uniformity of the resistor directly affects the accuracy of graphic input, so a resistor with particularly excellent uniformity is required, and it is relatively expensive considering its accuracy and resolution. Become something.

Two resistive films are required, one for the X coordinate and one for the Y coordinate, so
It also has the disadvantage of reduced transparency.

In addition, the electromagnetic three-conductor type has electric wires arranged in a matrix, so it is not transparent and is not suitable for use over a document, display, etc.

Furthermore, with conventional coordinate input devices that use ultrasonic vibration,
A method is used to detect the delay time during which vibrations generated by a human-powered pen propagate through a vibration transmission plate and reach a conversion element. In this method, when surface waves are used, if you touch or place an object on the vibration transmission plate when inputting coordinates with an input pen, or if there is a scratch on the surface of the vibration transmission plate, There is a drawback that the surface waves cannot pass through that part, the surface waves cannot reach the sensor, and coordinate detection cannot be performed.

On the other hand, in the case of a plate wave propagating through a thin plate-like object, the above-mentioned phenomenon is not as pronounced as in a surface wave, and even if a hand is placed on the propagation medium, the wave can pass through the wave, although the vibration is somewhat attenuated. Therefore, in order to construct a coordinate input device based on this method, it goes without saying that more stable coordinate detection can be performed by using a plate wave than by using a surface wave.

A plate wave is a wave that propagates through a finite thickness, and is also called a Lamb wave. However, considering the configuration, size, weight, and energy of human vibration (which greatly affects power consumption) of the device, for example, a vibration transmission plate is a wave that propagates through a finite thickness. , if the material is aluminum,
Its thickness ranges from a few tenths of a millimeter to about 2 to 3 mm at most. Therefore, as the coordinate input device becomes larger, the vibration transmission plate also becomes larger, which not only deforms the human power surface greatly when inputting coordinates, resulting in poor operability, but also permanently reduces mechanical strength. I can't keep it.

[Means for Solving the Problems] In order to solve the above problems, in the present invention, vibrations manually applied 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 support member is provided that directly contacts the vibration transmission plate on a surface and supports the vibration transmission plate, and the vibration transmission speed of the support member is determined by the vibration transmission speed of the vibration transmission plate. We adopted a configuration that is set slower than the speed.

[Function] According to the above configuration, the vibration transmission speed of the support member that is in direct surface contact with the vibration transmission plate and supports the vibration transmission plate is set to be slower than the vibration transmission speed of the vibration transmission plate. The vibration wave component transmitted to the vibration sensor is not affected by interference of vibration transmitted through the support member. Furthermore, since the vibration transmission plate is supported by the support member, strength in terms of human power is guaranteed.

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

FIG. 1 shows the overall structure of a coordinate input device employing the present invention. The apparatus shown in FIG. 1 is for performing coordinate manual input using a vibrating pen 3 on a human powered tablet comprising a vibration transmitting plate 8.

The vibration transmitting plate designated by the reference numeral 8 in the figure transmits the vibration transmitted from the vibrating ben 3 to three vibration sensors 6 provided at its corners.

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 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.

A vibrator 4 built into the vibrator 3 is connected to a vibrator drive circuit 2.
Driven by. A drive signal for the vibrator 4 is supplied as a low-level pulse signal from the arithmetic and control circuit 1 shown in FIG. 1, and a vibrator drive circuit 2 capable of low-impedance driving
After being amplified by a predetermined gain, the signal is applied to the vibrator 4. electrically transmitted.

The vibration frequency of the vibrator 4 is selected to a value that can generate plate waves in the vibration transmission plate 8. Further, when driving the vibrator, a vibration mode in which the vibrator 4 mainly vibrates in a direction perpendicular to the vibration transmission plate 8 is selected. 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 susceptible to the effects of scratches, obstacles, etc. on the surface of the vibration transmission plate 8 compared to surface waves.

FIG. 2 shows a support structure around the vibration transmission plate of the coordinate input device according to the present invention. In Fig. 2, reference numeral 8 denotes a vibration transmission plate as an input tablet, which is made of a metal plate such as aluminum alloy, and its thickness is within a few mm in order to efficiently transmit plate waves with little input energy (power consumption of the vibrator). It's Toshide. Reference numeral 7 indicates an anti-reflection material that prevents the vibration input by the vibration ben 3 from reflecting on the end face of the vibration transmission plate 8 and interfering with the waves directly input to the vibration sensor. Reference numeral 31 indicates an anti-reflection material for the coordinate input effective area. Anti-reflection material 7
This is the upper case of the input tablet in which the vibration transmission plate 8 is positioned on the outside of the input tablet and the vibration transmission plate 8 is fixed together with the support member 30 by screws (32). The support member 30 reinforces the thin vibration transmission plate 8 and ensures the strength of the input surface.

A vibration sensor 6 is fixed to the back surface of the vibration transmission plate 8 corresponding to the inside of the upper case 31 in the peripheral area of the vibration transmission plate 8, and this vibration sensor 6 detects the vibration manually applied from the vibration bench 3. Ru.

In this embodiment, the material (plastic or the like), thickness, etc. of the support member 30 are selected so that the vibration transmission speed of the support member 30 is slower than the vibration transmission speed of the vibration transmission plate 8. The reason for this will be explained below.

FIG. 3 schematically shows vibrations transmitted through the vibration transmission plate 8 and the support member 30. Here, it is assumed that vibration is applied to the vibration transmitting plate 8 from the vibration vent 3 at point A. At that time, when the state of vibration at point A is shown with the time axis plotted on the horizontal axis, it becomes as shown by reference numeral 2A in FIG. Further, when the vibration passes through the support member 30, a vibration as indicated by reference numeral 2B is excited. If the beginning of the input vibration of the vibration transmission plate 8 reaches the 0 point after a certain time, its waveform will similarly become as shown by reference numeral 2C in FIG. 3.

Here, unlike the present embodiment, if the wave propagating through the support member 30 is faster than the speed propagating through the vibration transmission plate 8, it will proceed to the dot position as shown by the symbol 2D, and if it is slower, it will become as shown by the symbol 2E. . The waves that propagate through these support members 30 adversely affect the vibration transmission plate 8, and if a phenomenon like symbol 2D occurs, it directly affects the waves 2C that have propagated through the vibration transmission plate 8.

The detection signal waveform detected by the vibration sensor 6 attached to the vibration transmission plate has a small output level in the state shown by reference numeral 2D, but it first passes through the support member 30 halfway and then passes through the vibration transmission plate 8 halfway. Then, the waves propagating only through the vibration transmission plate 8 are detected. In other words, if the vibration transmission speed of the support member 30 is faster, the waves transmitted by the vibration transmission plate 8 and the support member 30 will interfere with each other, causing the vibration waveform on the vibration transmission plate 8 to be detected by the vibration sensor 6 to be This results in distortion and a decrease in the accuracy of the coordinate input device itself.

Conversely, if the vibration transmission speed in the support member 30 is slower than the transmission speed in the vibration transmission plate 8 as in this embodiment, the waveform detected at the 0 point will not be affected even if the vibration transmission plate 8 is provided. Therefore, in the coordinate detection process described later, accurate coordinates can be determined based on the accurate vibration transmission time. value can be obtained.

The above explanation describes the phenomenon at a certain point on the vibration transmission plate 8-8-, but if the support member 30 and the vibration transmission plate 8 are in contact in the same way, the support member 30
Interference occurs due to the interference of the transmitted waveform of the vibration transmission plate 8. However, even in that case, if the speed of the wave passing through each vibration transmission plate 8 is slower than that of the vibration transmission plate 8, the vibration wave 2C that should be detected will not be affected, and the vibration sensor 6 will be able to accurately detect the vibration wave 2C. A vibration detection waveform can be obtained.

Note that the vibration transmission plate 8 may be made of glass, and the support member 30 may be made of a transparent material such as acrylic. When using transparent materials for these members, it is possible to place a document at the bottom of the input tablet and use it for tracing purposes, or to place a display device at the bottom of the tablet to display the trajectory input from the tablet. It is possible to do so.

In particular, when a display is used, by displaying handwritten characters, figures, etc. in the same size at the input position, good operability similar to that of writing on paper can be achieved. Furthermore, it goes without saying that the coupling structure between the support member 30 and the vibration transmission plate 8 is not limited to screwing.

Referring again to FIG. 1, 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 the waveform detection circuit 9 and converted into detection signals that can be processed by the arithmetic control circuit 1 in the subsequent stage. Arithmetic control device 1
performs vibration transmission time measurement processing and detects the coordinate position of the vibration ben 3 on the vibration transmission plate 8.

FIG. 4 shows the structure of the arithmetic control circuit 1 shown in FIG.

Here, the structure of the drive system of the vibrating ben 3 and the vibration detection system using the vibration sensor 6 are mainly shown. The vibration detection and coordinate input processing will be explained below.

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 the figure, 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 manually inputted to each human-powered boat 15.

A timing signal manually input from the waveform detection circuit 9 is input to the input boat 15 and stored in a 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.

FIG. 5 explains the detected waveform manually input to the waveform detection circuit 9 of FIG. 1 and the vibration transmission time measurement process based on the detected waveform. In FIG. 5, reference numeral 41 indicates a drive signal pulse applied to the vibrating ben 3. As shown in FIG. Ultrasonic vibrations transmitted from the vibration ben 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. 5 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 vibration sensor 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 a point on a certain waveform, for example, a peak, is detected as indicated by reference numeral 43 in FIG.
(1) Although this equation relates to one of the vibration sensors 6, the distances between the other two vibration sensors 6 and the vibration ben 3 can be expressed using the same equation.

Furthermore, in order to determine coordinate values with higher precision, processing based on phase signal detection is performed. Phase waveform 4 in Figure 5
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 = n · λp + Vp + tp
... (2) becomes. Here, λp is the wavelength of the elastic wave, 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). Here N is O
Use an appropriate value. For example, N=
2, and if the fluctuation of the group delay time tg is within ±1/2 wavelength, n can be determined.

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

In order to measure the two vibration propagation times tg and tp shown in FIG. 5, the waveform detection circuit 9 can be configured as shown in FIG. 6, for example.

In FIG. 6, 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 comparator detection circuit 58 from this Tg signal and the original signal delayed by the delay time adjustment circuit 57, and is inputted to the arithmetic control circuit 1.

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

If the number of sensors is generalized to h, then h detection signals each of envelope delay time Tgl~h and phase delay time "rpt~h" are input to the arithmetic control circuit 1.

In the arithmetic control circuit of FIG. 1, the above Tgl~h1Tpl~
The h signal is input manually 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 vibrating pen, the latch circuit 14 receives data indicating the respective delay times of the envelope and the phase.

As shown in FIG. 7, when the three vibration sensors 6 are arranged at the positions S1 to S3 at the corners of the t-thin motion transmission plate 8, the vibration pen 3 is moved from the position P by the process explained in relation to FIG. Straight-line distances d1 to d3 to the positions of each vibration sensor 6 can be determined.

Furthermore, the arithmetic control circuit 1 calculates the linear distance 11i11dl~d.
3, the coordinates (x, y) of the position P of the vibrating pen 3 can be determined from the 3-square theorem as shown in the following equation.

x= X/2+(di + d2) (di
-dz)/zx-(4)y-Y/2+(di+d3
) (di - d3)/2Y... (5) where X
%Y is the vibration sensor 6 at the positions S2 and S3 and the origin (position S
l) is the distance along the X and Y axes of the sensor.

In the manner described above, the position coordinates of the vibrating pen 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 the vibration transmitting plate, and the coordinates of the vibrating pen on the vibration transmitting plate are determined. In the coordinate input device for detecting the vibration transmission plate, a support member is provided that directly contacts the vibration transmission plate on a surface and supports the vibration transmission plate,
Since the vibration transmission speed of this support member is set to be slower than the vibration transmission speed of the vibration transmission plate,
Since the vibration transmission speed of the support member that directly contacts the vibration transmission plate and supports the vibration transmission plate is set to be slower than the vibration transmission speed of the vibration transmission plate, the vibration wave component transmitted to the vibration sensor is is not affected by the interference of vibrations transmitted through the support member, and can perform accurate coordinate detection based on the undistorted vibration detection waveform.By supporting the vibration transmission plate with the support member, it is possible to reduce the amount of human effort required. It has excellent effects such as guaranteed strength.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the configuration of a coordinate input device employing the present invention, FIG. 2 is an explanatory diagram showing the configuration of a vibration transmission plate and a support member in the coordinate input device employing the present invention, and FIG. An explanatory diagram explaining the operation of the support structure of the vibration transmission plate, Fig. 4 is a block diagram showing the structure of the arithmetic control circuit in Fig. 1, and Fig. 5 explains the measurement of the distance m between the vibrating pen and the vibration sensor. FIG. 6 is a block diagram showing the configuration of the waveform detection circuit of FIG. 1, and FIG. 7 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... Human powered boat O... Support member 2... Envelope detection circuit 4.58... Signal detection circuit 9... A/D conversion circuit 5 Sanyu Saka 11 B'o-, F diagram with the Asahi flea.

Claims (1)

[Claims] 1) In a coordinate input device that detects vibrations input from a vibrating pen using a plurality of sensors provided on a vibration transmitting plate to detect the coordinates of the vibrating pen on the vibration transmitting plate, A coordinate input device characterized in that a support member is provided to support a vibration transmission plate in contact with the support member, and a vibration transmission speed of the support member is set to be slower than a vibration transmission speed of the vibration transmission plate.