JPS6238925A - Coordinate reader using elastic wave - Google Patents

Abstract

PURPOSE:To increase the sampling rate of coordinates by generating an elastic wave by a coordinate indicator and receiving the elastic wave by transducers installed at the edge part of a tablet substrate. CONSTITUTION:A pulse signal for elastic wave excitation is generated by a signal generating circuit 3 and applied to a coordinate reader 2, a signal which synchronizes with the leading edge of the pulse signal is generated by a signal generating circuit 3 to trigger a counter 4 to begin to count up, and the coordinate reader 2 which receives the pulse signal makes its electrostrictive element to generate the elastic wave. The elastic wave is propagated in a tablet substrate 1 to reach the transducers 5, 6, 7, and 8; and the wave is converted into an electric signal, which is inputted to a signal processing circuit 9 and amplified. Further, its noises are removed, its waveform is shaped, and then a signal indicating the arrival of the signal is sent to the strip trigger input terminal of the counter 4. Then, the counter 4 stops counting and holds information proportional to the propagation time of the elastic wave and this information is processed by a coordinate arithmetic circuit 10 to find the distance between a vibration input device 2 and the transducers.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a coordinate reading device using one elastic wave.

[Summary of the invention]

This invention provides a coordinate reading device using elastic waves.
By generating an elastic wave from a coordinate indicator, propagating this elastic wave into the tablet board, receiving it with a converter, and reading the coordinates, it is no longer necessary to excite the elastic waves separately for the Y-axis and the Y-axis as in the conventional method. Therefore, the sampling rate for coordinate reading can be increased.

[Conventional technology]

9 Conventional devices that detect coordinates using elastic waves include [
iTriple E Transaction on Electronic Computers J (IEEE Trans
action on Electronic Comp
uters) October 1964 issue, pages 609-611.

There is one described in Japanese Patent Publication No. 56-32669. FIG. 3 shows a schematic configuration of the conventional device. That is, a pulse signal is applied to the transducers 22 and 23 installed at the edge of the tablet substrate 21 to generate an acoustic wave or a surface acoustic wave, and at the same time, the counter 24 is triggered. The elastic wave or surface acoustic wave propagating through the tablet substrate 21 is picked up by the coordinate indicator 25, which passes through the counter 24 to complete the counting. At this time, counter 24
Since the content of is proportional to the propagation time of the elastic wave or surface acoustic wave, the position coordinates of the coordinate indicator 25 can be known by appropriately selecting the clock frequency of the counter 24.

[Problem that the invention seeks to solve]

However, in the conventional coordinate reading device using elastic waves, the Y-axis and the Y-axis converter 22 and 2 are used to read the coordinates once.
3 must be alternately pulse-driven at a constant cycle to alternately excite the X-axis elastic waves and Y-axis elastic waves to the tablet substrate 21, which means that the time required to read the coordinates is long (that is, the sampling rate is low). There was a problem. This leads to the problem that when inputting coordinate values by continuously changing them (for example, when inputting handwritten characters), input coordinates may be omitted. For example, if handwritten characters are input at a fast writing speed and a coordinate reading device with a low sampling rate is used, the number of sampling points will decrease and omissions will occur in the written stroke information. As a result, when handwritten strokes are displayed, omissions occur in the display, and when pattern recognition is performed, problems such as a decrease in recognition rate occur.

[Means for solving problems]

In order to solve the above problems, the present invention has a configuration in which an elastic wave is generated from a coordinate indicator and is received by a converter installed at the edge of the tablet substrate, thereby increasing the coordinate sampling rate. I made it possible to do this.

[Effect]

When using the coordinate reading device configured as described above, in order to read the coordinates once, an elastic wave is excited from the coordinate indicator, and this elastic wave is transmitted to the X
Since the coordinate converter and the Y coordinate converter=3- can be used to receive signals separately, the sampling rate can be doubled compared to the conventional method.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a diagram showing the configuration of the coordinate reading device of the present invention. Reference numeral 01 is a tablet substrate, and a uniform isotropic material such as metal or glass is used for elastic wave propagation. A coordinate indicator 2 has an electrostrictive element for excitation of elastic waves therein, and this electrostrictive element is connected to one output terminal of the signal generating circuit 3.

Further, the other output terminal of the signal generating circuit 3 is connected to the input terminal of the start trigger of the counter 4. on the other hand.

Transducers 5 and 6 are provided on the surface and edge of the tablet substrate 1.
・7 and 8 are installed to receive 9 elastic waves and convert them into electrical signals.

The converters 5, 6, 7, and 8 are electrically connected to input terminals of the signal processing circuit 9. The output terminal of the signal processing circuit 9 is connected to the input terminal of the counter 4. The output terminal of the counter 4 is connected to the input terminal of the coordinate calculation circuit 10. In FIG.

To avoid cluttering the diagram, the signal processing circuit 9 and counter 4 are shown as one each, but in reality, one is connected to each of the converters 5 and 6, 7, and 8. .

In the coordinate reading device configured as described above, a pulse signal for excitation of elastic waves is generated from the signal generating circuit 3 and is applied to the coordinate reading device 2. Further, the signal generating circuit 3 generates a signal synchronized with the rising edge of the pulse signal, and triggers the counter 4 to start counting. Upon receiving the pulse signal, the electrostrictive element of the coordinate indicator 2 vibrates and generates an elastic wave.

The elastic wave propagates through the tablet substrate 1 and the transducers 5 and 6/7
・After reaching 8 and being converted into an electrical signal.

The signal is input to the signal processing circuit 9. The signal processing circuit 9 amplifies the input signal, removes noise, shapes the waveform, and sends a signal indicating that the signal has arrived to the input terminal of the counter 4.0 Counter 4 stops counting. It holds information proportional to the propagation time of one elastic wave. This information is processed by the coordinate calculation circuit 10 to determine the distance (that is, corresponding to the coordinates) between the vibration input device 2 and the converter. Although not shown in the figure, each converter has a signal processing circuit and a counter, and the coordinate indicator and distance data for each converter are input to the coordinate calculation circuit 10, and coordinate values are determined using multiple distance data. Calculated by

As described above, according to the present invention, it is not necessary to alternately excite two elastic waves with respect to the X axis and the Y axis in order to read coordinates once.

FIG. 2 shows an embodiment of the coordinate indicator according to the present invention. A vibrating body (A) 11 in the figure is a cylindrical rod having one end formed into a conical shape, and an electrostrictive element 12 is installed at the other end. Reference numeral 13 denotes a vibrating body (B), which is installed on a surface opposite to the surface on which the vibrating body (B) of the electrostrictive element 12 is installed.

That is, the structure is such that the electrostrictive element is sandwiched between the vibrating body (A) and the vibrating body (B). A lead wire 14 is connected to the electrostrictive element 12, and a pulse signal is applied via this lead wire 14.

The coordinate indicator in the upper part allows efficient excitation of elastic waves. The reason for this will be explained below.

The minimum component of the coordinate indicator for generating elastic waves and propagating them to the tablet substrate may be a combination of a vibrating body (A) and an electrostrictive element, or a combination of a vibrating body (B) and an electrostrictive element. However, in these cases, when a signal is applied to the electrostrictive element to cause it to vibrate, the W motion is transmitted to each vibrating body as an elastic wave, while also being transmitted from one surface of the electrostrictive element to the air. This emission of vibration into the air results in a loss of two elastic waves for the tablet. Therefore, if a vibrating body (B) is provided as in the present invention.

The elastic waves transmitted to the vibrating body (B) are reflected by the end surface of the vibrating body (B) (the surface opposite to the surface on which the electrostrictive element is installed),
It is propagated to the vibrating body (A). As a result, the vibrations of the electrostrictive element can be efficiently transmitted to the tablet and two substrates.

Further, the diameter of the electrostrictive element 12 is different from that of the vibrating body (A) and the vibrating body (
If the diameter is larger than B), the electrostrictive element 12 will have a part that comes in contact with the vibrating body and a part that is outside the vibrating body and does not come into contact with the vibrating body, resulting in the generation of multiple vibration modes and the waveform of two elastic waves. Since they are complex and appear in multiple numbers, signal processing becomes difficult. Therefore, in the present invention, the diameter of the electrostrictive element 12 is set to be equal to or smaller than the diameter of the vibrating body (A).

[Effects of the Invention] As explained above, the present invention has a simple configuration in which an elastic wave is generated from a coordinate indicator and the elastic wave is received by a transducer installed at the edge of the tablet substrate, contrary to the conventional method. in,
There is no need to excite elastic waves separately for the X-axis and Y-axis for coordinate reading, and therefore the sampling rate can be easily increased.

[Brief explanation of drawings]

, indicates. FIG. 2 shows the transverse flute of the coordinate indicator according to the present invention. FIG. 2 shows the structure of the coordinate reading device according to the present invention. FIG. 3 shows the configuration of a conventional coordinate reading device. 1・21・・・・・・Tablet board 2 ・
・・・・・・Coordinate indicator 3・26・・・・・・・・・
・Signal generation circuit 4, 24...Counter 5, 6, 7, 8, 22, 23...Converter 9
．． 27... Signal processing circuit 10...
・・・・・・More than coordinate calculation circuit

Claims (3)

[Claims] (1) A coordinate reading device that uses elastic waves as a coordinate reading means, which has a tablet substrate, a converter and a coordinate indicator installed on the surface of the tablet substrate and at the edge, and generates an elastic wave from the coordinate indicator. A coordinate reading device using elastic waves, characterized in that the elastic waves are propagated into a tablet substrate and then received by the converter. (2) The coordinate indicator is composed of an electrostrictive element and a plurality of vibrating bodies that respectively contact the vibrating front and back surfaces of the electrostrictive element, and reads the coordinates using elastic waves according to claim 1. Device. (3) The electrostrictive element used in the coordinate indicator is constructed so that its diameter is equal to or less than the diameter of the vibrating body. Coordinate reading device used.