JP2531804B2 - Coordinate input device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an input pen used in a digitizer for setting coordinates on a propagation medium using ultrasonic vibration.

[Background technology]

As an operation method of the digitizer, an electromagnetic induction method and a resistance matrix method have been conventionally used.

Among them, in the electromagnetic induction method, a strong magnetic field is applied to the plate base, electromagnetic pulses are sent in the XY directions of the plate base, and the phase difference of the electromagnetic pulse determined by the positional relationship (coordinates) on the plate base is determined. This is a method of detecting with a stylus pen and knowing the position of the stylus pen head.

On the other hand, in the resistance matrix method, the conductive rubber is arranged in a grid on the plate base, and the position coordinate of the pen tip is determined by the resistance value that changes with the writing pressure when the conductive rubber is pressed with a pen (ordinary pen). A way to know.

[Problems to be Solved by the Invention]

However, in the above-mentioned digitizer of the electromagnetic induction system, it is necessary to apply a strong magnetic field to the plate base, and the structure is relatively complicated, so that it is expensive.

Further, the resistance matrix type digitizer is inexpensive, but there is a problem that the resolution is low due to the limitation of the resolution due to the size of the conductive rubber.

Therefore, the inventor of the present invention has developed an ultrasonic digitizer as a third method capable of obtaining high resolution at low cost. This is a method in which the vibration transmitted from the head of the digitizer input pen to the propagation medium is detected by a detection means such as a reception sensor, and the coordinate data of the head position is captured based on the delay time until the vibration reaches. However, the following inconveniences have become apparent during the development process.

When the coordinates are set, the head of the digitizer input pen is brought into contact with the propagation medium. At this time, the writing pressure of the head changes the contact pressure between the head and the propagation medium. A change also occurs in the propagation waveform and the waveform level of the vibration wave in. Therefore, even if the vibration wave is transmitted from a certain position on the propagation medium, the delay time until it reaches the detection means varies depending on the writing pressure of the head,
There was a problem that an error occurred in the coordinate data due to the measurement error of the delay time. Also, if the vibrating element is fixed in the case and the piezoelectric vibrator is always connected to the drive circuit, the vibration wave is transmitted to the propagating medium only by placing the digitizer input pen on the propagating medium. There was a risk that coordinate data would be captured in.

Therefore, an object of the present invention is to improve the accuracy of determining the coordinates of an input pen used in an ultrasonic digitizer and to cause the propagation medium to vibrate if the head portion carelessly touches the propagation medium. To prevent them from joining.

[Means for solving the problem]

In order to solve the above-mentioned problems, the present invention joins a piezoelectric vibrator to the base end surface of an amplification horn whose tip side is a head portion, and a vibration element slidably housed in a case, and the head portion. The piezoelectric vibrating unit includes a biasing unit that elastically biases the vibrating element so as to project outside the case, and a contact probe for applying a driving voltage when the pressure on the biasing unit reaches a predetermined value. A coordinate input device that outputs vibration by contacting a child, wherein the contact probe is arranged so as to face an upper surface electrode of a piezoelectric vibrator, and the surface of the upper surface electrode is covered with a conductive rubber. Provided is a coordinate input device, wherein a driving voltage from a contact probe is applied to the piezoelectric vibrator by contacting the conductive rubber.

[Action]

According to the present invention, unless the head portion is pushed into the case, the top electrode of the piezoelectric vibrator does not come into contact with the contact probe to generate vibration in the piezoelectric vibrator, so that vibration is output from the head portion. Therefore, there is no inconvenience that the digitizer input pen is accidentally placed on the propagation medium and the coordinate data is erroneously captured.

Further, when the head portion is pressed against the propagation medium, for example, when the writing pressure of the head portion reaches a predetermined value, the vibrating element is pushed into the case against the elastic force of the biasing means, and the upper surface electrode contacts the contact probe. The vibration generated upon contact with the piezoelectric vibrator can be output from the head unit. Therefore, when the vibration is output from the head portion to the propagation medium, a constant writing pressure (or a constant contact pressure between the head portion and the propagation medium) is applied to the head portion by the biasing means, It is possible to improve the measurement accuracy of the delay time of the vibration wave by stabilizing the propagation waveform in the propagation medium.
The accuracy of coordinate data can be improved.

Moreover, in the present invention, since the surface of the upper surface electrode is covered with the conductive rubber, even when the upper surface electrode and the tip surface of the contact probe are not arranged in parallel, the contact probe is made of the conductive rubber. When pressed, the conductive rubber elastically deforms along the tip surface of the contact probe, and the upper surface electrode and the contact probe can be surely brought into surface contact with each other via the conductive rubber. Further, the impact of the contact between the upper surface electrode and the contact probe can be alleviated by the elasticity of the conductive rubber. Therefore, a stable contact load state can be obtained between the upper surface electrode and the contact probe, contact failure such as chattering that occurs between the upper surface electrode and the contact probe can be prevented, and the output waveform can be stabilized. it can.

〔Example〕

 Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 and 2 are cross-sectional views of the digitizer input pen 5, in which the vibrating element 4 is incorporated in the pen type case 6. This vibrating element 4
Is a bottom surface electrode 13b of a piezoelectric vibrator 3 such as a piezoelectric ceramic or a crystal resonator bonded to the base end surface of the amplification horn 2 with an adhesive. ing. Although various shapes can be used as the amplification horn 2, in the illustrated example, the columnar portion 9 and the conical portion 10 are integrally formed into a stepped shape.
The material of the amplification horn 2 is preferably metal such as aluminum or stainless steel or high hardness resin such as engineering plastic. As shown in FIG. 3, an upper surface electrode 13a is formed on the upper surface of the piezoelectric vibrator 3, and the upper surface electrode 13a is a sheet-shaped conductive rubber 8a.
Coated with The vibrating element 4 is slidably delivered in a case 6 having a substantially tubular shape, and the head portion 1 at the tip projects from a through hole 11 at the tip of the case 6. Further, a coiled spring 7 (biasing means) having an appropriate spring constant is compressed and housed in the case 6, and the spring 7 presses the base end surface of the amplification horn 2 to move the vibrating element 4. The head portion 1 is elastically biased in the protruding direction. On the other hand, the end face of the columnar portion 9 forming the step is a through hole.
The vibrating element 4 is prevented from coming off at a predetermined position by contacting the stopper 12 at the edge of 11. A conductive contact probe 14 is arranged at the center of the case 6 so as to face the upper surface electrode 13a of the piezoelectric vibrator 3.
The a and the contact probe 14 act as a switch. A lead wire 15 for applying a pulsed driving voltage to the piezoelectric vibrator 3 is connected to the contact probe 14 and the spring 7, respectively. The lead wire 15 connected to the spring 7 is a spring 7 and an amplifier. It is always electrically connected to the lower surface electrode 13b of the piezoelectric vibrator 3 through the base end surface of the working horn 2 (a conductive film is formed when the amplifying horn 2 is not made of metal). Therefore, as shown in FIG.
Contact probe and stop
14 is separated from the upper surface electrode 13a, and the piezoelectric vibrator 3
Since no drive voltage is applied to the head section 1, vibration does not occur in the head section 1. Similarly, even if the head portion 1 is pressed by the propagation medium 16, while the writing pressure of the head portion 1 is small, the vibration element 4
Does not retreat and the upper surface electrode 13a and the contact probe 14 are separated, so that the piezoelectric vibrator 3 does not vibrate. On the other hand, when the writing pressure of the head unit 1 reaches a predetermined value, the second
As shown in the figure, the vibrating element 4 is retracted and the upper electrode 13
When a contacts the contact probe 14 via the conductive rubber 8 and becomes conductive, the circuit for applying the drive voltage to the piezoelectric vibrator 3 is closed, and the drive voltage is applied to the piezoelectric vibrator 3 mechanically. Vibration is generated, and this vibration is amplified by the amplitude expanding action of the amplification horn 2 and output from the head unit 1. Therefore, it is possible to vibrate the piezoelectric vibrator 3 while maintaining the writing pressure of the head unit 1 at a predetermined value and output the amplified vibration from the head unit 1 (in other words, the vibration is output from the head unit 1). Sometimes, the writing pressure of the head unit 1 is held at a predetermined value), which makes it possible to stabilize the propagation waveform and waveform level of the vibration wave, measure the delay time with high accuracy, and calculate the coordinate data. The accuracy can be increased. Further, since the upper surface electrode 13a is brought into contact with the contact probe 14 via the conductive rubber 8, the impact when the upper surface electrode 13a contacts the contact probe 14 can be alleviated by the elasticity of the conductive rubber 8. Bounce does not occur at the time of contact, and chattering between the upper surface electrode 13a and the contact probe 14 can be prevented. Further, even when the tip surface of the contact probe 14 and the upper surface electrode 13a are not parallel to each other, the conductive rubber 8
By elastically deforming, a reliable surface contact with the contact probe 14 can be obtained, and contact failure can be prevented. By thus stabilizing the contact load state between the upper surface electrode 13a and the contact probe 14, the output waveform can be stabilized, and the delay time measurement accuracy can be further improved.

Since the above writing pressure is determined by the pressing force of the spring 7, it can be set by adjusting the spring constant of the spring 7 and the amount of compression when the spring 7 is housed in the case 6. FIG. 5 shows the result of measurement of the relationship between the writing pressure of the head and the variation of the delay time. Writing pressure is 200gr ~ 7
Even if it changes in the range of 00gr, the fluctuation of the delay time is small,
When the writing pressure is less than 200 gr, the delay time fluctuates significantly, and the coordinate measurement accuracy deteriorates extremely in this unstable region. Therefore, the measurement accuracy can be improved by setting the spring constant of the spring 7 so that the writing pressure of the head portion 1 when the upper surface electrode 13a comes into contact with the contact probe 14 falls within the range where the fluctuation of the delay time is small. , Especially the 5th
As shown in the figure, it is preferable to set the delay time within a stable region in which the variation in delay time is gentle.

Next, a method for setting coordinates on the sheet-like propagation medium 16 using the digitizer input pen 5 and taking in the coordinate data will be described with reference to FIG. The propagation medium 16 is usually contained in a plate-shaped case (not shown) or the like, and propagates an oscillating wave in each direction along the surface thereof. Receiving sensors 17 are attached to a plurality of places (three places in the illustrated example) of the propagation medium 16 so that the vibration wave propagating through the propagation medium 16 can be received or detected. Detection signal is sent to the detection circuit 18. The lead wire 15 of the digitizer input pen 5 is connected to a drive circuit 19,
A signal transmission / reception path is formed between the drive circuit 19, the detection circuit 18, and the arithmetic circuit 20.

Then, the head portion 1 of the digitizer input pen 5
When the writing pressure reaches a predetermined value by pressing on the propagation medium 16, the upper surface electrode 13a comes into contact with the contact probe 14, and when a pulsed driving voltage is applied from the driving circuit 19 to the piezoelectric vibrator 3,
The piezoelectric vibrator 3 causes a resonance phenomenon to excite vibration of a specific resonance frequency (and an integral multiple thereof). This mechanical vibration is amplified by the amplification horn 2 and output from the head unit 1. At this time, if the head portion 1 of the digitizer input pen 5 is in contact with a certain portion of the propagation medium 16 as shown in FIG. 4, the amplified vibration of the head portion 1 causes the propagation medium 16 to travel.
Coordinates are set on the propagation medium 16 as they are transmitted to the.
This vibration uniformly spreads in each direction as a vibration wave from the contact point of the head unit 1, and when it reaches the mounting position of the reception sensor 17, it is detected by the reception sensor 17, and each reception sensor 17
Detection signal is sent to the detection circuit 18. In the detection circuit 18,
The delay time (or the delay time difference) until the vibration reaches the position of each reception sensor 17 is measured. The arithmetic circuit 20 determines the XY coordinates of the position set by the head unit 1 based on the delay time information obtained from the detection circuit 18,
Output as coordinate data.

〔The invention's effect〕

As described above in detail, according to the present invention, the contact probe is arranged so as to face the upper surface electrode of the piezoelectric vibrator, the surface of the upper surface electrode is covered with conductive rubber, and the contact probe is made of the conductive rubber. Since the drive voltage from the contact probe can be applied to the piezoelectric vibrator by making contact, the top electrode and the contact probe are surely brought into surface contact with each other by the simple configuration of covering the surface of the top electrode with conductive rubber. It is possible to stabilize the contact load state, and it is possible to reduce the impact at the time of contact between the contact probe and the piezoelectric vibrator that are arranged opposite to each other, so that the output waveform can be stabilized. .

[Brief description of drawings]

1 and 2 are cross-sectional views showing a state in which an upper surface electrode is separated from a contact probe and a cross-sectional view in a state in which the upper surface electrode is in contact with the contact probe, and FIG. A partially enlarged front view of the vibrating element, FIG. 4 is a perspective view for explaining the usage and operating principle of the digitizer, and FIG. 5 shows the relationship between the writing pressure of the head and the variation of the delay time. It is a graph shown. 1 ... Head part, 2 ... Amplification horn 3 ... Piezoelectric vibrator, 4 ... Vibrating element 6 ... Case 7 ... Spring (biasing means) 8 ... Conductive rubber, 13a ... Top electrode 14 ……Contact probe

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Joji Eihei 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inoue Jiro 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Murata Manufacturing Company (72) Inventor Shiro Makino 2 26-10 Tenjin, Nagaokakyo City, Kyoto Stock Company Murata Manufacturing Company (72) Inventor Jun Tayoda 2 26-10 Tenjin, Nagaokakyo City, Kyoto Murata Manufacturing Co., Ltd. (56) Reference JP-A-1-112418 (JP, A) JP-A-63-73413 (JP, A) JP-A-60-156131 (JP, A)

Claims (1)

(57) [Claims] 1. A vibrating element, wherein a piezoelectric vibrator is joined to a base end surface of an amplifying horn having a head portion on the tip side, and a vibrating element slidably housed in a case, and the head portion protruding outside the case. A vibrating element that vibrates the vibrating element elastically, and a contact probe for applying a drive voltage to the piezoelectric vibrator when the pressure on the vibrating means reaches a predetermined value, causes vibration. A coordinate input device for outputting the contact probe, the contact probe being arranged to face the upper surface electrode of the piezoelectric vibrator, the surface of the upper surface electrode being covered with conductive rubber, and the contact probe being brought into contact with the conductive rubber. The coordinate input device is characterized in that a drive voltage from a contact probe is applied to the piezoelectric vibrator.