JPH0792724B2 - Coordinate input device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a coordinate input device, and more particularly to vibration transmission of the vibrating pen by detecting vibration input from a vibrating pen by a vibration sensor provided on a vibration transmitting plate. The present invention relates to a coordinate input device that detects coordinates on a board.

[Prior Art] Various input devices have been conventionally known as coordinate input devices. In this type of device, a coordinate system is set on a predetermined input surface, and an input member of a predetermined method is used to perform input on the input surface to detect coordinate information in the coordinate system on the input surface.

As a detection method, an input tablet is configured by arranging resistance films or conductive films facing each other, and a film such as a finger or a pen that makes the films arranged in contact with each other contact, or an input member such as an ultrasonic pen is used. A method is known in which ultrasonic vibration is input to an input tablet composed of a vibration transmission plate and the like, and coordinate values are detected from the vibration transmission time on the tablet.

With the method that uses ultrasonic vibration, the tablet can be made of a transparent material such as an acrylic plate or glass plate, so you can place the input tablet on a liquid crystal display etc. and use it as if you were writing an image on paper. A sensible information input / output device can be configured.

In the ultrasonic method, a plurality of vibration sensors including piezoelectric elements are provided on a vibration transmission plate, ultrasonic vibration input from a vibrating pen is detected, and input coordinates are determined by calculation from the vibration transmission time.

The number of vibration sensors provided on the vibration transmission plate is at least two. However, in this case, both of the vibration sensors must be provided on the sides of the vibration transmission plate or the like, and the input must be performed only on one side of the line connecting the two vibration sensors.

When the number of vibration sensors is two, the hardware is simple, but the calculation tends to be complicated, and the arithmetic processing tends to be long due to a microprocessor or the like. Therefore, since the hardware is not so complicated and the calculation can be easily performed, it is common to provide three vibration sensors at the corners of the vibration transmission plate.

[Problems to be Solved by the Invention] However, when using the minimum required number of sensors such as two or three as described above, the distance between sensors increases as the effective input surface increases. , Therefore,
The vibration transmission distance to the sensor at the time of input becomes long.

For example, when the sensors are attached to the three corners, respectively, and when the vibration is input from the corners of the input surface where the sensor is not provided, the vibration transmission distance becomes maximum and the vibration transmitted to the vibration sensor is Highest damping. Therefore, the gain of the amplifier that amplifies the output of the vibration sensor must be large. On the other hand, when the vibration input point is directly above one sensor (when the vibration sensor is provided on the back side of the vibration transmission plate), the vibration intensity input to the vibration sensor is higher than that when the above-mentioned maximum attenuation is obtained. Is tens or hundreds of times higher.

As described above, the amplifier that amplifies the output of the vibration sensor needs to have a sufficient dynamic range even when the input level is low and has a wide dynamic range that does not clip even at the maximum input level. There is a problem that such a high quality amplifier is very expensive. Conversely, if the amplifier cannot secure a sufficient dynamic range, the performance and functions of the entire device will be limited, such as reducing the input surface.

Even if a high-quality amplifier is configured, it is necessary to increase the power supply voltage in order to widen the dynamic range of the amplifier, which requires a configuration such as boosting the power supply voltage, which is costly. There was a problem.

[Means for Solving Problems] In order to solve the above problems, according to the present invention, the vibration pen detects vibrations input from the vibration pen by a plurality of vibration sensors provided on the vibration transmission plate. In the coordinate input device for detecting the coordinates on the vibration transmission plate, a comparison unit for comparing whether or not each level of the signals obtained from the plurality of vibration sensors is a predetermined value or more, and a result of the comparison by the comparison unit. Excluding means for excluding the signal of the vibration sensor whose level is equal to or higher than the predetermined value as invalid, and computing means for calculating coordinates using the signals obtained from the remaining vibration sensors not excluded by the excluding means. Adopted the configuration that has.

[Operation] According to such a configuration, it is compared whether or not each level of the signals obtained from the plurality of vibration sensors is equal to or more than a predetermined value,
As a result, the signal of the vibration sensor whose level is equal to or higher than the predetermined value is excluded as invalid, and the coordinates are calculated using the signals obtained from the remaining vibration sensors that are not excluded. Therefore, if the predetermined value of the level is appropriately set according to the dynamic range of the amplifier that amplifies the output signal of the vibration sensor, the signal of the vibration sensor whose waveform is distorted due to the saturation of the amplifier may be used for the coordinate calculation. In addition, coordinate detection can be performed with high accuracy using a signal without distortion.

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

FIG. 1 shows the structure of an information input / output device adopting the present invention. The information input / output device of FIG. 1 causes the input tablet composed of the vibration transmission plate 8 to input coordinates by the vibrating pen 3, and the display 11 'composed of a CRT arranged on the input tablet in accordance with the input coordinate information. The input image is displayed on.

In the figure, reference numeral 8 is a vibration transmission plate made of acrylic, glass plate or the like, and one vibration is transmitted from the vibration pen 3 at the center of each of the four sides and one at the center. The vibration sensor 6 is transmitted.

These vibration sensors 6 are for detecting the vibration input from the vibration pen 3 via the vibration transmission plate 8. The coordinates of the vibration pen 3 on the vibration transmission plate 8 are detected by measuring the transmission time of the ultrasonic vibration from the input point to the vibration sensor 6, but in the present embodiment, all five sensors are always used. Instead, a sensor suitable for coordinate calculation is selectively used by the method described below.

The vibration transmitting plate 8 has its peripheral portion supported by an antireflection material 7 made of silicon rubber or the like in order to prevent the vibration transmitted from the vibrating pen 3 from being reflected at the peripheral portion and returning toward the central portion. ing.

The vibration transmission plate 8 is a CRT (or a liquid crystal display, etc.),
It is arranged on a display device 11 'capable of dot display, and dot display is performed at a position traced by the vibrating pen 3. That is, a dot display is performed at a position on the display 11 ′ corresponding to the detected coordinates of the vibrating pen 3, and the image composed of elements such as points and lines input by the vibrating pen 3 is written on paper. Appears after the locus of the vibrating pen as you did.

Further, according to such a configuration, a menu is displayed on the display 11 ', and the vibrating pen is used to select the menu item, or a prompt is displayed to bring the vibrating pen 3 into contact with a predetermined position. Can also be used.

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

The drive signal for the vibrator 4 is supplied as a low-level pulse signal from the arithmetic control circuit 1, amplified by a predetermined gain by the vibrator drive circuit 2 capable of low impedance driving, and then applied to the vibrator 4.

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

The vibration frequency of the vibrator 4 is selected to a value capable of generating a plate wave on the vibration transmission plate 8 such as acrylic or glass. Further, when the vibrator is driven, a vibration mode in which the vibrator 4 mainly vibrates in the direction perpendicular to the vibration transmission plate 8 is selected. Further, by setting the vibration frequency of the vibrator 4 as the resonance frequency of the vibrator 4, it is possible to perform efficient vibration conversion.

The elastic wave transmitted to the vibration transmitting plate 8 as described above is a plate wave, and has an advantage that it is less susceptible to scratches and obstacles on the surface of the vibration transmitting plate 8 as compared to surface waves.

Each vibration sensor 6 provided on the vibration transmission plate 8 is also composed of a mechanical-electrical conversion element such as a piezoelectric element. The output signal of each of the vibration sensors 6 is input to the waveform detection circuit 9. The waveform detection circuit 9 determines the detection timing by waveform processing of the output signal of the vibration sensor 6. The arithmetic control circuit 1 measures the vibration transmission time based on the timing signal output from the waveform detection circuit 9, and detects the coordinate position of the vibration pen 3 on the vibration transmission plate 8. The counter 1b is used to measure the vibration transmission time.

The detected coordinate information of the vibrating pen 3 is processed in the arithmetic and control circuit 1 according to the output system by the display 11 '. That is, the arithmetic control circuit controls the output operation of the display 11 'via the video signal processing device 10 based on the input coordinate information.

FIG. 2 is a layout of the sensors of the coordinate input device used in this embodiment. In the figure, S (x, y) and P (x, y) respectively indicate the arrangement position of each vibration sensor 6 and the coordinates of the vibration input point. Further, reference character A indicates an area where the coordinate input is effective (determined by a reflected wave or the like at the end of the input surface).

In this configuration, when an elastic wave is generated at point P in the figure, the sensor that the vibration reaches first is S4,
Below is the order of S0, S3, S1, S2. Therefore, the time required for the vibration to reach the sensor is t4≤t0≤t3≤t1≤t2 (1). Here, if there are only the minimum sensors required for coordinate calculation, depending on the position of the coordinate input point P,
The vibration input from the point P is attenuated by the time it reaches the sensor and drops to the noise level, which may occur depending on the size of the propagating body. Therefore, there is a drawback that the size of the vibration transmission plate 8 is naturally limited.

For the above reasons, more vibration sensors 6 are attached to the vibration transmission plate 8, and a sensor necessary for calculating coordinates at a certain point is selected from the vibration transmission plate 8 so that the coordinates can be detected even when the vibration transmission plate 8 becomes large. It is possible to

In the case of the present embodiment, one vibration sensor 6 is provided at the center of each side of the vibration transmission plate 8 and one vibration sensor 6 is provided at the central portion of the vibration transmission plate 8. This performs coordinate detection by three sensors. In this case, the maximum length of the distance between the vibration input point and the three sensors can be minimized regardless of the position of the vibration input point P.

The arrival time t of the plate acoustic wave from the vibration input point to the sensor is counted by the arithmetic control circuit 1 using the counter 1b. The distance d is the traveling speed of the elastic wave is v,
Each sensor coordinate can be calculated by v × t
Distances corresponding to the vibration transmission times t0, t1, t2, t3, and t4 from S0 to S4 are d0, d1, d2, d3, and d4, respectively.

FIG. 3 is a processing flowchart of the coordinate input device of the present embodiment stored in the ROM 1a of the arithmetic control circuit 1.

First, in step S1, initialization of internal clocks, flip-flops, etc. is performed by initialization.

In step S2, the vibrator of the vibrating pen 3 is driven and the counter is started.

In step S3, elastic wave detection signals from all the sensors are received from the reception waveform detection circuit 9. If the detection signal is not received within the predetermined time, the process is skipped from step S11 and another process is performed.

Next, the levels of the detection signals received in step S4 are compared. At this time, if the vibration input point comes very close to the sensor as shown in FIG. 4, the output signal obtained from this sensor is saturated depending on the saturation input level of the amplifier.

This saturation input level setting value corresponds to the extent to which the output signal saturates as the vibration input point approaches from the sensor, and the size of the vibration transmission plate, sensor layout, and amplifier cost. It is changed as appropriate.

In FIG. 3, when there is a sensor whose output signal is saturated in step S5, the signal from the sensor is ignored in step S12.

When the detection signal levels have the same value (sensor S1 = sensor
In the case of S3, etc.), the process proceeds from step S6 to step S13, and the same signal level is obtained according to a predetermined rule (for example, "use the younger of the same value sensor as the sensor required for coordinate detection"). Decide which of the sensors to use.

In step S7, determine the sensor number required for coordinate detection,
In step S8, coordinate calculation is performed by the sensor determined above. Here, an example of a calculation formula used for coordinate calculation is shown below.

If there is no sensor with saturated output signal: Here, in the equation (2), when dx = d2, α = 1, dx = d4
In the case of α = −1, and in the case of dy = d1 in equation (3) β
When = 1 and dy = d3, β = −1.

On the other hand, when there is a saturated sensor (in the present embodiment, the sensors S1, S2, S3, and S4 are outside the coordinate input effective area A, so only the sensor S0 can be saturated), the remaining four sensors Using Becomes

In this case, the maximum value of the distance between the vibration input source and the sensor is the distance between the sensors at the corners, that is, between S1 and S2, between S2 and S3, and between S3 and S4.
If the upper limit of the amplifier is set so as to be equal to or less than the distance between S4 and S1, the maximum distance between the vibration input source and the sensor can be equal to or less than the above-described inter-sensor distance.

Referring again to FIG. 3, the calculation is performed in step S8, and when the coordinates are thus determined, the coordinates are RA in step S9.
It is stored in M and output to the external display drive circuit 10 or the like to end one cycle.

Hereinafter, this is repeated according to the sampling number. The output to the display drive circuit 10 or the like may be a display of the point indicated by the coordinates stored in the RAM or the like on the display 11, or may be transmission of coordinate value data to another device. .

As described above, according to the present embodiment, the vibration transmission plates are provided with more vibration sensors 6 than the minimum required number.
Since the sensor used for coordinate calculation is determined according to the signal level obtained from, even if the output of a certain sensor saturates or the detection level is insufficient, another sensor should be used. The coordinate calculation can be reliably performed. Further, since the vibration sensor 6 having an appropriate output level can be selected and used for coordinate calculation, a relatively inexpensive amplifier having a narrow dynamic range can be used for amplifying the output signal of the vibration sensor 6.
In addition, the restriction on the vibration transmission distance regarding vibration damping can be relaxed, and the area of the coordinate input surface can be easily increased.

As mentioned above, the greater the distance between the vibration input source and the sensor, the smaller the vibration reaching the sensor due to damping. As one method, a method of increasing the vibration energy generated from the vibrator in the vibrating pen serving as the vibration input source can be considered. It is also conceivable to increase the vibration propagation arrival time by increasing the driving voltage of the vibrator or increasing the vibrator. However, in both cases, the size of the vibration transmission plate is limited, which is not advantageous in terms of cost. In this embodiment, five sensors are attached to detect the coordinates, but the number may be more than that depending on the size of the vibration transmitting plate. By providing more sensors, it becomes possible to easily cope with a large-area input surface by using the same sensor, amplifier, and vibrator.

Further, although one sensor is attached in the coordinate input area in this embodiment, a plurality of sensors may be attached depending on the size of the vibration transmitting plate. That is, the coordinate position can be detected by changing the algorithm for detecting the coordinate depending on the number and position of the sensors.

EFFECTS OF THE INVENTION As is apparent from the above description, according to the present invention, the vibration input from the vibrating pen is detected by the vibration sensors provided on the vibration transmitting plate, and the vibration transmitting plate of the vibrating pen is detected. In the coordinate input device for detecting the coordinates at, the level of each of the signals obtained from the plurality of vibration sensors is compared with a predetermined value or more, and as a result, the signal of the vibration sensor with the level being the predetermined value or more is detected. Excluded as invalid, and adopted a configuration to calculate the coordinates using the signals obtained from the remaining vibration sensor not excluded, so the predetermined value of the level,
If you set it appropriately according to the dynamic range of the amplifier that amplifies the output signal of the vibration sensor, the signal of the vibration sensor whose waveform is distorted due to the saturation of the amplifier will not be used for coordinate calculation, and you can use the signal without distortion. Coordinates can be detected with high accuracy. Then, by lowering the predetermined value of the level, even if the power supply voltage of the amplifier is lowered to reduce the dynamic range, coordinate detection can be performed with high accuracy, and an inexpensive amplifier can be used. It is possible to provide a coordinate input device that does not require a configuration such as boosting the power supply voltage, can operate at a relatively low voltage, is low in cost, and has high reliability. Further, by adopting the above configuration, an excellent effect that there is no problem that the size of the input surface is limited by the sensitivity of the vibration sensor and the dynamic range of the amplifier after the vibration sensor is obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing the structure of an information input / output device adopting the present invention, FIG. 2 is an explanatory diagram showing the placement of a vibration sensor and coordinate detection processing, and FIG. 3 is the arithmetic and control unit of FIG. FIG. 4 is a flowchart showing the control procedure of FIG. 4, and FIG. 4 is an explanatory view showing the arrangement of the vibration sensor and the coordinate detection processing. 1 ... Arithmetic control circuit, 3 ... Vibration pen 4 ... Vibrator, 6 ... Vibration sensor 8 ... Vibration transmission plate

Claims (2)

[Claims] 1. A coordinate input device for detecting vibrations input from a vibrating pen by a plurality of vibration sensors provided on a vibration transmitting plate to detect coordinates of the vibrating pen on the vibration transmitting plate. Comparing means for comparing whether or not the respective levels of the signals obtained from the sensors are equal to or higher than a predetermined value, and exclusion as a result of the comparison by the comparing means, invalidating the signal of the vibration sensor whose level is equal to or higher than the predetermined value. A coordinate input device comprising: means for calculating coordinates using signals obtained from the remaining vibration sensors not excluded by the exclusion means. 2. The selection means for selecting the signal of the vibration sensor used for the coordinate calculation from each of the signals obtained from the remaining vibration sensors not excluded by the exclusion means. The coordinate input device according to the first item of the range.