JPH11353104A - Coordinate input device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an internal electric circuit from short-circuiting owing to foreign matter intruding from the outside in an ultrasonic-wave vibration type coordinate input device. SOLUTION: A shield case 62 is provided in the inside of a housing 61 of a device to cover a vibration sensor 6a, an electrode 63, a preamplifier 401 etc., on a vibration transmission plate 8 to carry out shielding them from an external noise. A case 62 is constituted by applying metal plating 621 of a ferromagnetic material to a magnetized material 622 which is a magnetized ferromagnetic material and is magnetized so that an intense magnetic field is formed specially at the side edge part 62a of the case 62. In the case that external foreign matter intrudes into the housing 61 through a gap formed with the transmission plate 8 and trys further to intrude into the case 62, when the foreign matter is a ferromagnetic body such as iron, it is attracted to the side edge part 62a of the case 62 with magnetic force and checked from intruding into the case 62. Consequently, an electric circuit in the case 62 is never short-circuited by the foreign matter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coordinate input device, and more particularly to a vibration input means for detecting a vibration input to an arbitrary input point on a vibration transmission plate by a vibration detection means provided at a predetermined portion of the vibration transmission plate. The present invention also relates to a coordinate input device for calculating coordinates of an input point based on a vibration transmission time from the input point to a vibration detecting means.

[0002]

2. Description of the Related Art As a coordinate input device for inputting coordinates by ultrasonic vibration, for example, as disclosed in Japanese Patent Publication No. 5-62771, a vibration sensor is provided on a tablet (vibration transmission plate) constituting a coordinate input surface. The vibration sensor detects vibration input to an arbitrary vibration input point on the coordinate input surface of the tablet, and calculates the coordinates of the input point based on a vibration transmission time from the input point to the vibration sensor. In this method, there is no need to perform any work on the tablet such as a matrix-shaped electric wire, so that an inexpensive device can be provided. Moreover, if a transparent plate glass is used for the tablet, a coordinate input device having higher transparency than other methods can be configured. Utilizing this high transparency, there is an input / output integrated device in which a liquid crystal display device and a coordinate input device of an ultrasonic vibration type are overlapped. In this device, coordinates can be directly input to the display screen, so that the visibility and the operability are excellent, and the spread thereof is expected in the future.

[0003]

FIG. 9 is a schematic sectional view showing a structure around a vibration sensor of a conventional example of the above-mentioned integrated input / output device. In the figure, reference numeral 81 denotes a housing of the apparatus. Reference numeral 82 denotes a vibration input pen for a coordinate input operation, which oscillates ultrasonic vibration. 83 is a vibration transmission plate (glass plate) constituting a coordinate input surface. 84 is a vibration transmission plate 8
3 is a vibration sensor provided at an end. Reference numeral 85 denotes an electrode for connecting the vibration sensor 84 to a subsequent circuit. 8
Reference numeral 6 denotes a liquid crystal display device.

[0004] The tip of the vibration input pen 82 is
The ultrasonic vibration oscillated from the pen 82 is transmitted from the input point and is detected by the vibration sensor 84 by making contact with an arbitrary input point on the coordinate input surface of the. Then, the coordinates of the input point are calculated based on the vibration transmission time from the input point to the vibration sensor 84.

The basic principle of this device is to calculate the coordinates of the input point based on the transmission time and the sound speed of the ultrasonic vibration. Therefore, the sound speed in the vibration transmission plate 83 is not only constant. It is preferable that the detection signal waveform detected by the vibration sensor 84 always has the same shape. For this reason, it is desirable that nothing besides the vibration transmission plate 83 be interposed in the transmission path of the ultrasonic vibration, so that a gap is formed between the housing 81 and the vibration transmission plate 83 as shown by the arrow in FIG. In this way, the housing 81 does not interfere with the vibration transmission of the vibration transmission plate 83.

However, if there is such a gap, there is a problem that external foreign matter easily enters the inside of the housing 81. In particular, when a metal foreign object enters the inside of the housing 81, the internal electric circuit is short-circuited, and the device malfunctions,
There is a possibility of causing an accident such as a malfunction or a fire, and there is a problem in reliability and safety of the device.

SUMMARY OF THE INVENTION It is an object of the present invention to prevent a short circuit of an electric circuit inside a coordinate input device of this kind due to a foreign substance that has entered from the outside, thereby improving the reliability and safety of the device.

[0008]

According to the present invention, there is provided a vibration transmitting plate and a vibration detecting means provided at a predetermined portion of the vibration transmitting plate. In a coordinate input device, a vibration input to an arbitrary input point on the vibration transmission plate is detected by the vibration detection means, and coordinates of the input point are calculated based on a vibration transmission time from the input point to the vibration detection means. A shield case made of a ferromagnetic material that covers the vibration detection means on the vibration transmission plate and shields from external noise, the shield case being at least partially magnetized and made of a ferromagnetic material When a foreign substance tries to enter the inside of the shield case from outside, the foreign substance is attracted by magnetic force to prevent the foreign substance from entering.

According to such a configuration, when a foreign object attempts to enter the shield case from outside, if the foreign object is made of a ferromagnetic material such as iron, the foreign object is attracted to the shield case by magnetic force, and Foreign matter is prevented from entering the shield case. Therefore, the circuit around the vibration detecting means in the shield case is not short-circuited by the foreign matter.

In addition, since this short circuit can be prevented beforehand,
The shield case and the casing of the coordinate input device can be arranged separately from the vibration transmission plate so as to form a gap between the vibration transmission plate, and can prevent interference with the vibration transmission of the vibration transmission plate.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

<Description of Overall Configuration of Coordinate Input Device> First,
The overall configuration of a coordinate input device according to an embodiment of the present invention will be described with reference to FIG.

In FIG. 1, reference numeral 1 denotes an arithmetic control circuit,
In addition to controlling the entire apparatus, the coordinates of the input point are calculated as described later, and the coordinate data is stored in the host computer 10.
To a serial cable. The details of the arithmetic control circuit 1 will be described later.

Reference numeral 2 denotes a pen code, through which various signals are transmitted from the arithmetic and control circuit 1 to a pen internal circuit 4 in the vibration input pen 3. Details of the vibration input pen 3 will be described later.

Reference numeral 8 denotes a vibration transmission plate made of a transparent plate material such as an acrylic or glass plate, the upper surface of which serves as a coordinate input surface. The upper surface of the vibration transmission plate is provided for preventing scattering when the vibration transmission plate 8 is broken. An anti-scattering film (laminate) made of PET, PET, or the like is attached via an adhesive layer. The coordinate input by the vibration input pen 3 is performed by touching the upper surface of the vibration transmission plate 8. In practice, this is performed by touching the area indicated by the symbol A indicated by the solid line in FIG. A vibration isolator 7 is provided on the outer periphery of the vibration transmission plate 8 to prevent (attenuate) the vibration reflected on the end face of the outer periphery of the vibration transmission plate 8 from returning to the center. further,
At each of the four corners at the end of the vibration transmission plate 8, vibration sensors 6 a to 6 d that convert mechanical vibration of a piezoelectric element or the like into an electric signal are fixed near the boundary of the vibration isolator 7.

Reference numeral 9 denotes a signal waveform detection circuit which processes a vibration detection signal input from each of the vibration sensors 6a to 6d to generate a signal indicating the arrival timing of the vibration in each vibration sensor. Output.

Reference numeral 11 denotes a display, such as a liquid crystal display device, capable of displaying on a dot-by-dot basis. The display 11 displays a dot at a position of an input point touched by the vibration input pen 3 based on an image signal output from the host computer 10. This can be seen through a transparent vibration transmission plate 8.

<Description of Vibration Input Pen> Next, the details of the vibration input pen 3 will be described with reference to FIG. As shown in FIG. 2, a pen internal circuit 4 built in the vibration input pen 3
It is composed of a vibrator drive circuit 41 and a vibrator 42.
The drive signal of the vibrator 42 is supplied as a low-level pulse signal from the arithmetic and control circuit 1, amplified by the vibrator drive circuit 41 with a predetermined gain, and applied to the vibrator 42. The electric drive signal is converted into mechanical ultrasonic vibration by the vibrator 42 and transmitted to the vibration transmitting plate 8 via the pen tip 5 of the pen 3. The vibrator drive circuit 42
May be provided not on the vibration input pen 3 but on the control board on the coordinate input device main body side.

The vibration frequency of the vibrator 42 is selected to a value at which a plate wave can be generated on the vibration transmission plate 8 made of glass or the like. Furthermore, the vibration input pen 3 is not limited to the above-described plate wave, and for example, when a surface wave propagating through the vibration transmission plate 8 is used as a detection wave, the frequency of the vibration generated by the vibration input pen 3 is It may be set to a value sufficiently high with respect to the thickness of the vibration transmission plate 8 (a state in which the wavelength λ of the wave propagating through the vibration transmission plate 8 becomes sufficiently small with respect to the thickness of the plate).

<Description of Operation Control Circuit> Next, the operation control circuit 1 will be described in detail. First, an outline of the operation will be described.
Every millisecond), a signal for driving the vibrator 42 of the vibration input pen 3 is output to the vibrator drive circuit 41, and time measurement by the internal timer (constituted by a counter) is started. The vibration generated by the vibration input pen 3 reaches each of the vibration sensors 6a to 6d with a delay according to the distance from the vibration input point on the vibration transmission plate 8.

The signal waveform detection circuit 9 is provided for each of the vibration sensors 6a to 6a.
6d, and a signal indicating the timing of arrival of vibration at each vibration sensor is generated by a waveform detection process described later. The arithmetic and control circuit 1 inputs this signal for each sensor and outputs the signal to each vibration sensor. The vibration transmission time from 6a to 6d is detected, and the coordinates of the vibration input point are calculated based on this. Further, the arithmetic and control circuit 1 outputs the calculated coordinate information of the input point to the host computer 10.

Next, the configuration and operation of the arithmetic control circuit 1 will be described in detail with reference to the block diagram of FIG.

In FIG. 3, reference numeral 31 denotes a microcomputer for controlling the arithmetic and control circuit 1 and the coordinate input device as a whole, and includes a CPU, an internal counter, and an R storing control procedures.
It is composed of an OM, a RAM used for calculations and the like, a nonvolatile memory for storing constants and the like.

32a to 32d are vibration sensors 6a to 6d
When a start signal for starting the driving of the vibrator 42 of the vibration input pen 3 is input to the vibrator driving circuit 41, Start timing. As a result, the start of timing and the detection of vibration by the sensor are synchronized, and the delay time (vibration transmission time) until vibration is detected by the vibration sensors 6a to 6d can be measured.

The vibration arrival timing signal output from the signal waveform detection circuit 9 in each of the vibration sensors 6a to 6d is
Counters 32a to 32d via detection signal input circuit 34
Is input to

When the determination circuit 33 determines that all the vibration arrival timing signals have been received, it outputs a signal to the microcomputer 31 to that effect. When the microcomputer 31 receives this signal from the determination circuit 33, the microcomputer 31 sends the signal from the counter 32a to 32d to the vibration sensor 6a.
The vibration transmission time up to 6d is read from the latch circuit,
The coordinates of the vibration input point on the vibration transmission plate 8 are calculated by performing a calculation described later.

By outputting the calculated coordinate information to the host computer 10 via the I / O port 35, it is possible to display dots or the like at positions corresponding to the vibration input points on the display 11, for example.

<Explanation of Vibration Transmission Time Measurement> Next, details of the measurement of the vibration transmission time from the vibration input point to the vibration sensors 6a to 6d and the measurement of the distance between the input point and the sensor based on the vibration transmission time will be described. This will be described with reference to FIGS. FIG. 4 is a block diagram showing a configuration of the signal waveform detection circuit 9, and FIG. 5 shows a signal waveform processed by each unit of the signal waveform detection circuit 9, and a description will be given of a process of measuring a vibration transmission time based on the signal processing. FIG. 4 is a signal waveform diagram for the present invention. Hereinafter, the case of the vibration sensor 6a will be described, but the description is the same for the other vibration sensors 6b to 6d. The circuit of FIG. 4 is similarly provided for the vibration sensors 6b to 6d.

As described above, the measurement of the vibration transmission time from the vibration input point to the vibration sensor 6a starts simultaneously with the output of the start signal to the vibrator drive circuit 41. At this time, a drive signal 51 shown in FIG. 5 is applied from the vibrator drive circuit 41 to the vibrator 42. The drive signal 51 is, for example, two short rectangular pulses. When the vibrator 42 is driven by the signal 51 and the operator brings the pen tip 5 of the vibration input pen 3 into contact with a desired input point on the upper surface of the vibration transmission plate 8, ultrasonic vibration is generated from the input point. Is transmitted.

The ultrasonic vibration proceeds after taking a transmission time corresponding to the distance from the vibration input point to the vibration sensor 6a.
It is detected by the vibration sensor 6a as a short detection waveform. The reason why the drive signal 51 is set to a short pulse is to prevent erroneous detection due to interference (superposition) between an unnecessary reflection component mainly at the end face of the vibration transmission plate 8 and the vibration to be detected, and to reduce the size of the entire apparatus. is there.

The output of the vibration sensor 6a detecting the vibration is amplified by the preamplifier 401 in FIG. 52 in FIG.
Shows the signal waveform of the detection output. The signal processing is performed on the envelope 521 and the phase 522 of the signal waveform 52 as follows.

First, in the processing of the envelope 521, the signal 52 is passed through a high-pass filter 402 to remove unnecessary vibration components, and the signal after passing is processed.
That is, since the processing of the envelope 521 is easily affected by the reflected wave, the short detection signal after passing through the high-pass filter 402 is used only for the envelope detection.

The envelope signal 53 is extracted from the detection signal after passing through the high-pass filter 402 by the envelope detection circuit 403.

The envelope signal 53 is input to an envelope inflection point detection circuit 404 and a gate signal generation circuit 406. The gate signal generation circuit 406 generates a reference level signal 541 obtained by attenuating the envelope signal 53 to an appropriate amplitude and adding a certain offset. The gate signal generation circuit 406 also receives the second-order differential output waveform 54 obtained by performing the second-order differentiation of the envelope signal 53 by the envelope inflection point detection circuit 404. The gate signal generation circuit 406 generates a gate generation signal 542 by comparing the second-order differential output waveform 54 with the reference level signal 541, and outputs the signal to the monostable multivibrator 407.

The monostable multivibrator 407 generates a gate signal 55 having a predetermined pulse width from the rising timing of the gate generation signal 542,
5 and output to the tp comparator 411.

The tg comparator 405 outputs the gate signal 5
The tg (group delay time) signal 501 is generated by using the zero-cross point while the gate signal 55 is open as an inflection point of the envelope with the fifth and second derivative waveforms 54 as inputs. The tg signal 501 is supplied to the arithmetic and control circuit 1.

On the other hand, in the processing relating to the phase 522 of the detection signal 52, first, the detection signal 52 is passed through a narrow band band-pass filter 409 to be a signal of a frequency component having a predetermined width.
Furthermore, the waveform is sliced (waveform level compression) by the slice circuit 410 to a predetermined amplitude level or less. The outputs of the phase signal 58 and the gate signal 55 are input to the tp comparator 411. tp comparator 411
Detects the zero-crossing point of the rising edge of the phase signal 58 in the predetermined order (second in FIG. 5) while the gate signal 55 is open, and outputs the signal 59 of the phase delay time tp as the output of the arithmetic control circuit 1. Supplied to

Here, the reference level signal 541 for outputting the gate generation signal 542 may be a variable level synchronized with the pulse of the drive signal 51 in accordance with the distance between the vibration input pen 3 and the vibration sensor 6a. When the fluctuation range of the detection level is large, setting the variable level is more effective because the detection point is stabilized.

Since the vibration used in the apparatus of the present embodiment is a plate wave, the relationship between the envelope 521 and the phase 522 of the detected waveform with respect to the transmission distance in the vibration transmission plate 8 indicates the transmission distance during the vibration transmission. It changes according to. Here, the traveling speed of the envelope 521, that is, the group velocity is Vg, and the traveling speed of the phase 522, that is, the phase velocity is Vp. The distance between the vibration input point of the vibration input pen 3 and the vibration sensor 6a can be detected from the group velocity Vg and the phase velocity Vp.

First, focusing only on the envelope 521, the speed is Vg. When a point on a specific waveform, for example, an inflection point is detected, the vibration input point and the vibration sensor 6a
Is given by d = Vg · tg (1), where tg is the vibration transmission time. This equation is for one of the vibration sensors 6a, but the same equation is used for the other three vibration sensors 6b.
6d and the distance between the vibration input point can be similarly expressed.

Further, in order to determine coordinates with higher accuracy, processing based on the detection of the phase signal is performed. Detection signal 5
From the phase delay time tp detected as described above from the second phase 522, the distance d between the vibration sensor and the vibration input point is as follows: d = n · λp + Vp · tp (2) Here, λp is the wavelength of the elastic wave, and n is an integer.
The above-mentioned integer n can be obtained by the equation (3) from the equations (1) and (2).

N = int [(Vg · tg−Vp · tp) / λp + ／] (3) As described above, since the plate wave is used as the detection wave, the distance of the group delay time tg to the distance This is why the linearity is not good, and the integer conversion is performed in Expression (3). A necessary and sufficient condition for obtaining an accurate integer n is shown in Expression (5) derived from the following Expression (4).

N ^* = (Vg · tg−Vp · tp) / λp (4) ΔN = n ^* −n ≦ 0.5 (5) That is, if the generated error amount is within ± 1/2 wavelength. ,
This shows that the integer n can be accurately determined even if the linearity of the group delay time tg is not good. The distance d between the vibration input point and the vibration sensor 6a can be accurately measured by substituting the determined n into the equation (2).

Incidentally, the distances between the other vibration sensors 6b to 6d and the vibration input points can be similarly measured with high accuracy.

<Description of Calculation of Input Point Coordinates> Next, details of the calculation of the coordinates of the vibration input point based on the measurement of the vibration transmission time and the distance will be described with reference to FIG.

Now, if the vibration sensors 6a to 6d are provided at positions Sa to Sd near the four corners of the vibration transmission plate 8 shown in FIG. 6, the vibration input pen is measured based on the measurement of the vibration transmission time described above. 3 from the vibration input point P to each of the vibration sensors 6a.
The linear distances da to dd to the positions 6 to 6d can be obtained. Further, based on the linear distances da to dd, the arithmetic control circuit 1 can obtain the coordinates (x, y) of the vibration input point P by the following equations (6) and (7) from the square theorem.

X = (da + dd) · (da−dd) / 2X (6) y = (da + db) · (da−db) / 2Y (7) where X is the distance between the vibration sensors 6a and 6d, and Y is This is the distance between the vibration sensors 6a and 6b.
, The coordinates of the vibration input point P can be calculated in real time.

In the above calculation, the calculation is performed using the distance information from the input point P to the three sensors. However, in the present embodiment, since four sensors are installed, the distance of one remaining sensor is set. Using the information, for example, the certainty of the output coordinates can be verified. Further, when the distance d between the input point and the sensor increases, the detection signal level decreases and the probability of being affected by noise increases. Therefore, the distance information of the sensor having the largest distance d is not used, and the remaining three sensors are used. The coordinates may be calculated. In this embodiment, four sensors are arranged and coordinates are calculated from the distance information of the three sensors. However, geometrically, the coordinates can be calculated by two or more sensors. It goes without saying that the number of sensors is set accordingly.

<Description of the Shield Structure of the Vibration Sensor Unit> Next, the shield structure of the vibration sensor unit will be described with reference to FIGS. Although the shield structure of the vibration sensor 6a is shown here, it goes without saying that the same shield structure is provided in the other vibration sensors 6b to 6d.

FIG. 7 is a sectional view showing the structure around the vibration sensor 6a.

In FIG. 7, reference numeral 61 denotes a casing of the coordinate input device, which covers the periphery of four sides of the vibration transmission plate 8.
The housing 61 is separated from the vibration transmission plate 8 so as not to interfere with the vibration transmission in the vibration transmission plate 8, and the right side edge 61 a of the housing 61 in the drawing is bent downward and the vibration transmission plate 8 is bent. Although it is close to the vibration transmission plate 8, the vibration transmission plate 8 is arranged so as to have a necessary gap to prevent interference with the vibration transmission.

A shield case 62 is provided inside the housing 61. The shield case 62 is necessary to prevent external noise from being mixed into the weak detection signal of the vibration sensor 6a. The shield case 62 includes a vibration sensor 6 a provided on an end of the vibration transmission plate 8, a vibration isolator 7,
It is arranged so as to cover and surround the electrode 63 and the preamplifier 401, and is connected to a frame ground (not shown) or the ground of the preamplifier 401. The electrode 6
Numeral 3 is for transmitting a detection signal of the vibration sensor 6a to the preamplifier 401.

The shield case 62 is separated from the vibration transmission plate 8 so as not to interfere with the vibration transmission in the vibration transmission plate 8, like the housing 61, and
Although the right side edge portion 62a in FIG. 2 is bent downward and approaches the vibration transmission plate 8, the right side edge portion 62a is
It is arranged so as to have a necessary clearance so as not to interfere with the transmission of vibration. The gap between the side edge 62a and the vibration transmission plate 8 communicates with the gap between the side edge 61a of the housing 61 and the vibration transmission plate 8.

The shield case 62 is configured by applying a ferromagnetic metal plating 621 to the surface of a magnetized material 622 obtained by magnetizing a ferromagnetic material such as cobalt nickel. The magnetized material 622 is particularly suitable for the vibration transmission plate 8.
Is designed so as to form a strong magnetic field at the side edge portion 62a which is close to. For example, as shown in FIG. 8, a portion of the magnetizing material 622 in the side edge portion 62a of the shield case 62 has a plurality of stripes having a predetermined width and has a magnetization pattern having alternately opposite polarities as viewed in the direction of the arrow in FIG. Magnetized. The metal plating 621 serves as a path for magnetic flux between the magnetic poles of the magnetic material 622, and serves to weaken the self-demagnetizing action of the magnetic material 622.

As described above, since the shield case 62 is magnetized, the housing 6 is removed from the gap between the housing 61 and the vibration transmitting plate 8.
1 is invaded by a metallic foreign matter,
If the metal is made of a ferromagnetic material such as iron, the foreign matter may enter the inside of the side edge 62a of the shield case 62.
, And is prevented from entering the shield case 62.

Therefore, the circuit around the vibration sensor 6a such as the electrode 63 and the preamplifier 401 is not short-circuited by the foreign matter, and a malfunction such as malfunction, non-operation, or fire of the device due to the short-circuit is prevented. be able to.
Further, in order to prevent these accidents, it is not necessary to fill the gap between each of the housing 61 and the shield case 62 and the vibration transmission plate 8, and the housing 61 and the shield case 62 do not interfere with the vibration transmission of the vibration transmission plate 8. Therefore, the accuracy of calculating the coordinates of the apparatus is not reduced. Thus, a coordinate input device excellent in reliability and safety can be configured.

In the above-described embodiment, the shield case 62 has a configuration in which the magnetic material 622, that is, the magnet is coated with the metal plating 621. However, the shield case 62 may be formed of only the magnetic material without applying the metal plating. However, in this case, since the coercive time becomes short, the shield case is configured to be easily replaceable.

Although the number of assembling steps is increased, the main body of the shield case 62 is formed of a non-magnetized ferromagnetic material, and corresponds to the side edge portion 62a opposed to the vibration transmission plate of the main body via a gap. The magnet may be fixed to the portion to be fixed with a double-sided tape or the like.

[0059]

As is apparent from the above description, according to the present invention, there is provided a vibration transmitting plate and vibration detecting means provided at a predetermined portion of the vibration transmitting plate. A coordinate input device for detecting vibration input to an arbitrary input point on the board by the vibration detecting means and calculating coordinates of the input point based on a vibration transmission time from the input point to the vibration detecting means; It has a shield case made of a ferromagnetic material that covers the vibration detecting means on the transmission plate and shields from external noise.
At least a portion is magnetized, so that when a foreign substance made of a ferromagnetic substance attempts to enter the shield case from the outside, the foreign substance is attracted by a magnetic force and is prevented from entering, so that the ferromagnetic substance is used. No foreign matter enters the shield case and short-circuits the circuit around the vibration detection means.
Accidents such as malfunction, non-operation or fire of the device due to the short circuit can be prevented beforehand, and the reliability and safety of the device can be improved. In addition, the shield case and the casing of the coordinate input device can be arranged separately from the vibration transmission plate so as to form a gap between the vibration transmission plate, and can prevent interference with the vibration transmission of the vibration transmission plate. ,
An excellent effect that the coordinate calculation accuracy is not reduced is obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an overall configuration of a coordinate input device according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing a schematic configuration of a vibration input pen of the device.

FIG. 3 is a block circuit diagram showing a detailed configuration of an arithmetic control circuit of the device.

FIG. 4 is a block circuit diagram showing a detailed configuration of a signal waveform detection circuit of the device.

FIG. 5 is a signal waveform diagram showing a signal waveform processed in each section of the signal waveform detection circuit.

FIG. 6 is an explanatory diagram for explaining a method of calculating coordinates of a vibration input point in the same device.

FIG. 7 is a schematic sectional view around a vibration sensor showing a shield structure around the vibration sensor in the same device.

FIG. 8 is an explanatory diagram showing an example of a magnetization pattern of the shield case in FIG. 7;

FIG. 9 is a schematic cross-sectional view of a peripheral portion of a vibration sensor for explaining a problem of a conventional coordinate input device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Operation control circuit 2 Pen code 3 Vibration input pen 4 Pen internal circuit 5 Pen point tip 6a-6d Vibration sensor 7 Vibration isolator 8 Vibration transmission board 9 Signal waveform detection circuit 10 Host computer 11 Display 61 Housing 62 Shield case 621 Metal Plating 622 Magnetizing material 63 Electrode 401 Preamplifier

Continuation of the front page (72) Inventor Ryozo Yanagisawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Yuichiro Yoshimura 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc.

Claims (2)

[Claims] 1. A vibration transmission plate, comprising: a vibration detection unit provided at a predetermined portion of the vibration transmission plate, wherein the vibration input unit transmits a vibration input to an arbitrary input point on the vibration transmission plate. In a coordinate input device for detecting by a detecting means and calculating coordinates of an input point based on a vibration transmission time from the input point to the vibration detecting means, the vibration transmitting means covers the vibration detecting means on the vibration transmitting plate and is shielded from external noise. A shield case made of a ferromagnetic material that performs magnetizing. At least a part of the shield case is magnetized. A coordinate input device characterized in that the coordinate input device is configured to adsorb and prevent intrusion. 2. A housing of the coordinate input device covers the shield case, and is disposed apart from the vibration transmission plate so as to form a gap between the housing and the vibration transmission plate. 2. The coordinate input device according to claim 1, wherein the case is also disposed apart from the vibration transmission plate such that a gap is formed between the shield case and the vibration transmission plate. 3.