JP3258159B2 - Ultrasonic detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic detecting apparatus for detecting the presence or absence or position of an object by ultrasonic waves.

[0002]

[Prior art]

Conventional example A: An ultrasonic detection device is composed of a panel arranged so as to cover a display screen of a general CRT or the like, and a control unit for controlling a detection operation. , The position (touch position) or presence / absence of the object is detected.

[0003] Available ultrasonic waves include surface acoustic waves (SAW: Surface Acoustic Wave) propagating on a solid surface.
ic Wave) and elastic waves propagating in solids (GAW:
Guided Acoustic Wave).

FIG. 9 shows a schematic plan view of an ultrasonic panel. The panel 1 is formed of a substantially rectangular glass having the same curvature as a liquid crystal panel or a CRT display or the like. In each part, a reflection array 3 including a plurality of reflection elements 2 printed with low-melting glass powder is formed. A rectangular portion surrounded by the reflection array 3 is a detection surface 6, and a transmitter 4 for transmitting an ultrasonic wave is provided at one end of two parallel reflection arrays 3 opposed to each other with the detection surface 6 interposed therebetween. A receiver 5 for receiving the ultrasonic wave transmitted from the transmitter 4 is attached to one end of the reflection array 3 to constitute a set of detection pairs. The position coordinates on the detection surface 6 are specified by two detection pairs perpendicular to each other on the panel 1. The reflection arrays 3 of the two detection pairs respectively correspond to the XY coordinate axes of the normal XY coordinate plane, and the reflection array 3 of the one detection pair
Is the X axis, the reflection array 3 of the other set of detection pairs corresponds to the Y axis.

FIG. 10A shows a state where a transmitter or a receiver for a surface acoustic wave is attached. The transmitter 4 and the receiver 5 are composed of a piezoelectric element 7 and a prism 8, and are provided on the surface of the panel 1. Attached to the aforementioned position. Further, a transmitter 4 and a receiver 5 of an elastic wave (GAW) propagating in a solid
Is directly attached to the end face of the panel 1 as shown in FIG. In the following description, the ultrasonic wave shown in FIG.
Description will be made by taking the surface acoustic wave shown in FIG.

Next, the operation principle of detecting the coordinate position of an object on the panel surface will be briefly described. As shown in FIG. 11A, when a 5.5 MHz transmitted shock wave is applied from the control unit to the piezoelectric element 7, vibration is generated in the piezoelectric element 7 and converted into a longitudinal wave in the prism 8. Prism 8 and panel 1
At the interface, the longitudinal wave is converted into a surface acoustic wave, propagates on the reflection array 3 on the panel 1, and a very small amount of energy is reflected at right angles by each reflection element 2 of the reflection array 3. The reflected surface acoustic waves propagate over the entire detection surface 6 of the panel 1 as shown by the arrow in FIG. 9 and propagate toward the opposing reflection array 3, and are reflected at right angles by the reflection array 3,
It is received by the piezoelectric element 7 of the receiver 5. The signal received by the receiver 5 has a long duration as shown in FIG. In this case, when an object comes into contact with the detection surface 6 of the panel 1 (touch occurs), elastic wave energy is absorbed by the contact portion, and a signal corresponding to the contact portion is lost as shown in FIG. , The depression H in the received signal
Appears as. In this case, an elastic wave passing through the shortest distance a, an elastic wave passing through the touch position b, or an elastic wave passing through the longest distance c in FIG. Touch position b from wave
And the elapsed time T of the received elastic wave corresponding to the longest distance c
By measuring 0 and T1, the coordinate component of the position (touch position) of the object 9 can be obtained.

Although the received wave shown in FIG. 11 is converted into a voltage by the receiving piezoelectric element, the time change of the voltage (amplitude) indicating the received wave is not uniform as shown in FIG.
In actuality, it becomes uneven on the time axis as shown in FIG. The shape of this amplitude is because the interface between the prism 8 and the panel 1, the reflection element 2, the panel surface, and the like are not necessarily uniform, and the surface acoustic wave does not propagate uniformly. Is determined as a unique shape (constant). When the user touches the panel 1 with a finger or the like, as shown by a dotted line in FIG. 12, a surface acoustic wave at a portion corresponding to the touch position is absorbed. The coordinate component of the touch position is calculated from the position on the time axis of the dent due to this absorption. That is, by transmitting the transmitting shock wave alternately to the transmitters 4 of the two pairs of detection pairs on the panel 1, the plane coordinate position of the touch position is calculated from the position of the dent due to the absorption on the X and Y coordinate axes, and the touch position is calculated. The coordinates are detected.

More specifically, first, when there is no contact object on the detection surface 6 (no touch is made), the voltage waveform of FIG.
High-speed sampling is performed by the D converter, and the sampled data is stored in the RAM. This stored data is
This is sampling data of surface acoustic waves received when no touch is made, and serves as a baseline (reference) for detecting touch-on later.

Next, at the time of normal detection, the received wave is sampled in the same manner, and the difference between the current sampling data and the data corresponding to the current sampling time previously stored in the RAM as a baseline is calculated. , Measured data at time t. This difference indicates a value indicating the presence of the absorption of the ultrasonic wave due to the contact of the object.
After memorizing the baseline, if there is no object contact,
The measured sampling data does not change and the difference from the baseline becomes zero.

FIG. 14 shows, by a dotted line, a dent of a received voltage waveform that appears when a finger is touched with respect to a baseline. Further, FIG.
FIG. 15 is an enlarged view of a dotted line portion indicating a touch in FIG. 14 and also represents a difference between a digital value of a base line and a digital value of a received voltage waveform. In FIG. 15, each sampling time shown on the time axis,..., T _n−2 , t _n−1 , t _n , t _{n + 1} , t
.., _{n + 2} ,... In the figure, the difference Δ
An is a maximum at time _t = t _n.

Conventionally, to determine the presence or absence of a touch and the touch coordinates, every time a transmitting shock wave is output from the transmitter 4,
The maximum difference ΔAn is obtained and compared with the reference level value Ath. ΔAn ≦ Ath... No touch, ΔAn> A
th · · · There touch, and judgment, and a touch has touch position coordinate components on the panel 1 a coordinate component obtained from the time t _n corresponding to ΔAn in the case of the touch coordinate position from the coordinate components of the X and Y coordinate axes Has been detected.

Conventional Example B A stylus used for input (touch-on) to the panel 1 of the above-described ultrasonic detection apparatus has been conventionally performed by an input with a finger capable of absorbing ultrasonic waves.

[0013]

[Problems to be solved by the invention]

Problem A The circuit of the control unit of the conventional ultrasonic detection device is easily affected by noise from a power supply circuit, a host computer, or electromagnetic waves. This is because sampling of the A / D conversion is performed at a high speed, and the internal impedance of the piezoelectric element 7 is high, so that external noise is easily picked up. For example, as shown in FIG. 16, an error E due to noise is superimposed on the A / D-converted sampling data, and in a normal case, the noise P is superimposed over the point R detected as the maximum value of the difference from the baseline. is detected as the maximum value the difference between the point and the point Q is increased, Therefore the touch position is incorrect sampling time corresponding to the point P or point Q without being calculated from the correct sampling time t _n corresponding to the R point t _P since obtained from or t _Q, so that the detection of the touch position being erroneous due to noise.

As shown in FIG. 17, although noise does not actually exceed the reference value for detecting a touch, noise is added as shown at point B to instantly exceed the reference value Ath. The fluctuation may cause erroneous operation such as erroneous detection or repeated touch / no touch.

SUMMARY OF THE INVENTION An object of the present invention is to provide a highly reliable ultrasonic detecting device capable of preventing erroneous detection due to noise and reliably detecting touch-on. It is another object of the present invention to provide a highly reliable ultrasonic position detecting device capable of preventing erroneous detection or fluctuation of coordinates due to noise and reliably detecting coordinates of a touch position.

It is another object of the present invention to prevent touch-on / touch-off chattering (repetition of touch-on / touch-off) due to electric noise and fluctuation of the touched finger pressure, and to reliably detect touch-on / touch-off. It is to provide an ultrasonic detection device. It is a further object of the present invention to provide a highly reliable ultrasonic position detecting device capable of reliably detecting the coordinates of a touch position.

Problem B When a finger is used as a conventional stylus used for input to the panel 1 of the above-described ultrasonic detection device, the input is different from that of a pen because it is soft and has a large contact surface with the panel surface. Handwriting input was difficult and the resolution was poor. Further, even with a tip having a small contact surface, a conventional pen or the like made of a hard material that hardly absorbs ultrasonic waves does not absorb ultrasonic waves, and thus cannot input itself. For this reason, the ultrasonic detection device cannot perform high-resolution handwriting input with a pen or the like, so that a pen computer or a PDA (Personal Digital Assist) or the like employs an electric induction type tablet or a resistive touch panel.
Ultrasound was not used.

[0018]

[0019]

[Means for Solving the Problems]

According to the ultrasonic detection apparatus of the present invention, there is provided a reference level detecting device for detecting whether or not the level of an ultrasonic signal passing through a receiver exceeds a predetermined reference level indicating the presence of an object absorbing the ultrasonic wave. Means, first reference time detecting means for determining whether or not the level of the ultrasonic signal exceeding the reference level detected by the reference level detecting means has continued for a first reference time or more; Means for outputting a touch-on signal indicating the presence of an object when it is detected that the level of the ultrasonic signal exceeding the reference level detected by the reference time detection means has continued for a first reference time or more;
A second reference time for determining whether or not the level of the ultrasonic signal exceeding the reference level detected by the first reference level detection means continues for a second reference time shorter than the first reference time; Touch-off indicating absence of an object when the detection means and the second reference time detection means do not detect that the level of the ultrasonic signal exceeding the reference level continues for more than the second reference time. Means for outputting a signal. Further, when the first reference time detecting means detects that the level of the ultrasonic signal exceeding the reference level continues for the first reference time or more, the first time point at which the reference level is passed And a coordinate calculating means for calculating the X or Y coordinate from the average at the second time point.

[0021]

[0022]

[0023]

The present invention indicates the presence of an object when it is detected that the level of the ultrasonic signal exceeding the reference level detected by the first reference time detecting means has continued for the first reference time or more. When a touch-on signal is output and the second reference time detecting means does not detect that the level of the ultrasonic signal exceeding the reference level continues for the second reference time shorter than the first reference time. To output a touch-off signal indicating the absence of an object.

[0024]

[0025]

[0026]

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A schematic configuration of an embodiment of an ultrasonic detection apparatus according to the present invention will be described with reference to FIG. In FIG.
The ultrasonic shock wave output from the shock wave generator 11 is supplied to the X-axis switch 13 and the Y-axis switch 14 via the transmission amplifier 12. Shock waves output from the X-axis switch 13 and the Y-axis switch 14 are respectively input to the X-axis transmitter 4a and the Y-axis transmitter 4b corresponding to the transmitter 4 provided in the panel 1 shown in FIG. Is done. The ultrasonic waves output from the X-axis transmitter 4a and the Y-axis transmitter 4b propagate in the X-axis direction and the Y-axis direction, respectively, with the panel surface as a surface acoustic wave, and are provided with the receiver provided in the panel 1 shown in FIG. 5 are received by the X-axis receiver 5a and the Y-axis receiver 5b, respectively. The surface acoustic waves received by the X-axis receiver 5a and the Y-axis receiver 5b are converted into ultrasonic electric signals and provided to the corresponding X-axis switch 15 and Y-axis switch 16, respectively.
The ultrasonic signal via 6 is input to the receiving amplifier 17.
X-axis switches 13 and 15 and Y-axis switches 14 and 16
Is controlled by a microprocessor 26, and one of the X-axis switches 13, 15 and the Y-axis switches 14, 16 is turned on and the other is turned off.

The ultrasonic signal amplified by the receiving amplifier 17 is sent to a demodulator 18 where the ultrasonic signal is
(Amplitude modulation) is detected and converted into a DC component. The output of the demodulator 18 is an A / D (analog / digital) converter 19
Where it is sampled at high speed over time. The sampling data from the A / D converter 19 is sent to an SRAM (static random access memory) 21 via a buffer 20 and stored therein.
When the sampling operation of the A / D converter 19 is completed, the CPU 23 of the microprocessor 26 writes the sampling data stored in the SRAM 21 via the buffer 22 to calculate whether or not an object touches the panel 1. And the calculation for obtaining the coordinates of the touch position is started. The above-described baseline sampling data serving as a reference for the touch determination is also stored in the SRAM 21 and written into the CPU 23 at the time of the determination. The CPU 23 controls the buffers 20 and 22 to adjust the direction of the data flow. The microprocessor 26 has a CPU 23 as well as a CP.
A RAM 24 used for storing the operation of U23 and a ROM 25 storing a program for the operation are provided.
The coordinate data of the touch-on / touch-off and the touch position determined by the CPU 23 are sent to the host computer 28 via the interface 27.

Next, the operation of detecting the presence / absence of touch-on of an object and the position coordinates according to the present invention will be described. First, prior to the detection operation, shock waves are output in the X-axis direction and the Y-axis direction, respectively, and the sampling data of the ultrasonic waves corresponding to the X-axis and the Y-axis are stored in the SRAM 21 as a baseline serving as a determination reference. Shall be X-axis switches 13 and 15 are turned on (Y-axis switch 1
The detection operation for the X-axis is performed in a state where 4 and 16 are off). That is, the shock wave is intermittently output from the shock wave generator 11, and the A / D of the ultrasonic electric signal based on the shock wave is output.
The sampling data via the converter 19 is stored in the SRAM 21 as measurement data. In the RAM 24, a reference level value and a reference time serving as a reference for determining the presence or absence of touch-on are set for the X axis and the Y axis, respectively. The CPU 23 performs an operation of detecting measurement data in accordance with an arithmetic program stored in the ROM 25.

FIG. 2 is a flow chart showing an embodiment of the present invention. In step S1, a sampling time (hereinafter referred to as a start value) for starting measurement data representing an ultrasonic electric signal and a sampling time for ending reception (hereinafter referred to as a start value) are shown. Less than,
End value) is read from the SRAM 21 and the CP
It is stored in the register of U23. In step S2, the reference level value and reference time for the X axis stored in the RAM 24 are written to the CPU 23. Next, step S
3 and the baseline sampling data and the measurement sampling data stored in the SRAM 21 are stored in the CPU 21.
23, the difference data between the measured sampling data and the baseline is calculated corresponding to each sampling time, and stored in the register of the CPU 23. Next, at step S4, as shown in FIG. 3, it is determined whether or not the difference data has exceeded the reference level value Ath stored in the register for each sampling time from the start value to the end value. the sampling time exceeds the level value Ath the first time point X _L, the reference level value a
The sampling time immediately before the following again the reference level from beyond th is stored in the registers as the second time point X _R. Next, the processing proceeds to step S5, the second time point _{X R} from the first time point _{X L} is subtracted with the reference level value time width _W beyond the Ath as shown in FIG. 3 ₍₌ X R _-X L)
Is calculated, and it is determined whether or not the time width W is equal to or longer than the reference time Wth stored in the X register. If it is determined that this is the case, the process proceeds to step S6, where the Y-axis switches 14 and 16 are turned on, and the same applies to steps S1 to S1 for the Y-axis.
When S5 is executed and it is determined that the measured sampling data of the ultrasonic wave of the Y-axis exceeds the reference level value of the Y-axis for the reference time or more, it is determined that an object touches the panel 1 (touch-on). If it is determined, the process proceeds to step S7.
In step S7, the sampling time X _O = (X _L
+ X _R ) / 2 is calculated, the position of the X axis corresponding to the time X _O is specified as the X coordinate of the touch-on, and the Y coordinate is specified similarly. In step S8, the CPU 23 sends data indicating touch-on to the host computer 28 together with the coordinate data.

If the difference data does not exceed the reference level value in step S4, or if the time width W is determined to be shorter than the reference time Wth in step S5 even if the difference data exceeds the reference level value, touch-on is performed. Is determined to have not existed, and without moving to step S6, X
The operation of detecting the next measurement sampling data is repeated on the axis. If it is not determined in step S6 that the measured sampling data on the Y axis exceeds the reference level value by the reference time or more, the touch-on is not detected and the detection operation is repeated without moving to step S7.

Next, another embodiment of the present invention will be described with reference to FIG.
This will be described with reference to the flowchart of FIG. FIG.
In step S11, the start value and the end value of the measurement data representing the ultrasonic electric signal are read from the SRAM 21 and stored in the register of the CPU 23. Step S1
In step 2, the reference level value for the X axis and the first reference time stored in the RAM 24 are written to the CPU 23. Next, proceeding to step S13, the sampling data of the baseline and the measurement sampling data stored in the SRAM 21 are read out by the CPU 23, and the data of the difference between the measurement sampling data and the baseline corresponding to each sampling time, respectively. Is calculated and the CPU 23
Is stored in the register. Next, the process proceeds to step S14.
Whether or not the difference data has exceeded the reference level value Ath stored in the register is determined for each sampling time from the start value to the end value, and the sampling time when the difference level exceeds the reference level value Ath is first determined at the first time X is _L, are stored in respective registers sampling time immediately before the following again the reference level from exceeding a reference level value Ath as a second time point X _R. Next, the process proceeds to step S15, where the second
From the time X _R is calculated first time point X _L is subtracted with the reference level value Ath traversal time width W (= X R _{-X L)} is first of said time width W is stored in the register of whether the reference time W ₁ or more is determined. Time width W is the case shown in FIG. 5 (A), it is determined that a touch-off from the first smaller than the reference time W _1, the time width W is the case shown in Fig. 5 (B)
Is determined to touch since it is the first reference time W ₁ or more. If it is determined in step S15 that the time width W is equal to or longer than the first reference time, the process proceeds to step S16, where Y
The axis switches 14 and 16 are turned on, and steps S11 to S15 are similarly performed for the Y axis. The measurement sampling data for the Y axis ultrasonic wave also changes the reference level value of the Y axis to the Y axis. If it is determined that the time exceeds the first reference time, touch-on is determined and step S1 is performed.
Move to 7. In step S17, the calculated sampling time _{X O = (X L + X} R) / 2 is the position of the X axis corresponding to said time _{X O} is identified as the X-coordinate of the touch, as well Y-coordinate are also specified. In step S18, the CPU 23 sends data indicating touch-on to the host computer 28 together with the coordinate data.

[0033] In step S19, the register of CPU23 said first second reference time shorter than the reference time of said 1 _{W 2} in place of the reference time _{W 1} is written from the SRAM 21. Next, the second reference time _{W 2} steps S11~S15 based on is repeated proceeds to step S20, whether the second reference time _{W 2} or more times the width W in the step S15 is stored in the register not Is determined. Time width W is the case shown in FIG. 5 (C) is determined to touch since it is the second reference time W ₂ or more is continued, the time width W is the case shown in FIG. 5 (D) is first The touch-off is determined because it is shorter than the reference time W2 of No. ₂ . The CPU 23 sends data indicating touch-off to the host computer 28. Thereafter, the same detection operation is repeated from S11.

Next, another embodiment of the present invention will be described with reference to FIG.
This will be described with reference to the flowchart of FIG. FIG.
In step S21, the start value and the end value of the measurement data representing the ultrasonic electric signal are read from the SRAM 21 and stored in the register of the CPU 23. Step S2
2, the first X-axis associated with the X-axis stored in the RAM 24.
Reference level value _{A 1} and the reference time of the Wth is written to the CPU 23. Next, the process proceeds to step S23, where the SRAM 21
Is read by the CPU 23, and the data of the difference between the measured sampling data and the baseline is calculated corresponding to each sampling time, and C is calculated.
It is stored in the register of PU23. Next, step S24
To transfer, first whether it exceeds the reference level value A ₁ is determined for each sampling time from the start value to the end value the difference data is stored in the register, beginning with the first reference level value A ₁ The sampling time exceeding the first time point _XL
And then, are stored in respective registers sampling time immediately before the following again the reference level from exceeding a first reference level value A ₁ as the second time point X _R. Next, the processing proceeds to step S25, the second time point X _R from the first time point X _L is subtracted by the first reference level value A ₁ of the time width W beyond
(= X R _{-X L)} is calculated, said time width W whether the stored reference time Wth above register is judged. Time width W is the case shown in FIG. 7 (A), it is determined that a touch-off from smaller than the reference time Wth in the first reference level value A _1, the time width W is the case shown in FIG. 7 (B) is a reference Since it is longer than the time Wth, it is determined that the touch-on is performed.
If it is determined in step S25 that the time width W is equal to or longer than the reference time Wth, the process proceeds to step S26, where the Y-axis switches 14 and 16 are turned on, and steps S21 to S25 are similarly performed for the Y-axis. If it is determined that the measurement sampling data of the ultrasonic wave of the axis exceeds the first reference level value of the Y axis by the reference time of the Y axis or more, it is determined that touch-on is performed, and the process proceeds to step S27. In step S27, the sampling time X _O =
_{(X L + X R) /} 2 is calculated, the position of the X axis corresponding to said time X _O is identified as the X-coordinate of the touch, as well Y-coordinate are also specified. In step S28, the CPU
23 sends data indicating touch-on to the host computer 28 together with the coordinate data.

In step S29, the register of the CPU 23 stores the first reference level value A1 in place of the _first reference level value A1.
A _second reference level value A2 smaller than the reference level value is written from the SRAM 21. Next, step S30
To step S based on the _second reference level value A2.
21~S25 are repeated, the second reference level value _{A 2} of the time width W of the measurement sampling data exceeded is determined,
In step S25, it is determined whether the time width W is equal to or longer than the reference time Wth stored in the register. In the case shown in FIG. 7C, the time width W is equal to or longer than the reference time Wth, so it is determined that the touch-on is continued. In the case shown in FIG. 7D, the time width W is longer than the reference time Wth. It is judged to be touch-off because it is small. The CPU 23 sends data indicating touch-off to the host computer 28. Thereafter, the same detection operation is repeated from S21.

When detecting touch-on, the first reference level value A ₁ and the first reference time W ₁ are used, and when detecting touch-off after touch-on is detected, the second reference level is used. a ₂ and may be configured to use the second reference time W _2. Further, when detecting a touch-off, the coordinates at the time of touch-off may be detected in the same manner as the coordinate calculation at the time of touch-on.

Next, an embodiment of a stylus used in the ultrasonic detection device of the present invention will be described with reference to FIG. As shown in FIG. 8A, the entire stylus 31 has the same size and shape as a pencil or a ball-point pen in use, and is formed so as to be suitable for handwriting input. The stylus 31 has a point 32 that directly contacts the surface of the panel 1,
And a bar-shaped portion 33 provided with the pointed end 32 at one end. As shown in FIG. 8 (B), the pointed portion 32 has a core 34 formed of rubber, sponge or the like as an ultrasonic absorbing member, and a non-super It is formed by a contact portion 35 coated with a metal which is a sound absorbing member. The rod portion 33 is formed of a hard material so as to be suitable for handwriting input.
Ordinary non-ultrasonic absorbing materials such as wood and metal may be used. The core portion 34 may be filled with a material other than rubber, which has a high ability to absorb ultrasonic waves, such as a solid or a liquid or a mixture of a liquid and a solid. Further, as shown in FIG. 8C, the entire tip 32 may be formed of rubber or the like which is an ultrasonic absorbing material. At the point 32, the panel 1 of the ultrasonic detection device
For this purpose, an ultrasonic absorbing material is used in such an amount that it has an appropriate amount of slip according to the material from which characters and the like can be input and that can detect the absorption of ultrasonic waves.

[0038]

As described above, according to the present invention, even if the level of the ultrasonic signal measured by electric noise exceeds the reference level instantaneously, it is not detected as a touch-on signal, and Even if the input to the input fluctuates and fluctuates near the reference level, the touch-on is not determined, and the touch-on can be reliably detected by preventing erroneous touch-on detection due to electric noise and chattering at the time of input. . Furthermore, this one invention is
The touch-on coordinates can be reliably obtained, and the detection of the coordinates is not erroneously recognized or the detected coordinates do not fluctuate unstablely due to the influence of electric noise or chattering at the time of input.

Further, according to the present invention, it is possible to reliably detect touch-on by preventing the above-described electric noise and chattering, and to surely detect touch-off without being affected by electric noise and chattering. Can be.

[0040]

[Brief description of the drawings]

FIG. 1 is a schematic overall configuration diagram of an ultrasonic detection device of the present invention.

FIG. 2 is a flowchart showing a detection operation of the ultrasonic detection device of the present invention.

FIG. 3 is a diagram for explaining the principle of the detection operation of FIG. 2;

FIG. 4 is a flowchart showing another detection operation of the ultrasonic detection device of the present invention.

FIG. 5 is a diagram for explaining the principle of the detection operation of FIG. 4;

FIG. 6 is a flowchart showing another detection operation of the ultrasonic detection device of the present invention.

FIG. 7 is a diagram for explaining the principle of the detection operation of FIG. 6;

FIG. 8 is a diagram showing an embodiment of a stylus used in the ultrasonic detection device of the present invention.

FIG. 9 is a diagram showing a panel surface of an ultrasonic detection device through which ultrasonic waves are propagated.

FIG. 10 is a diagram showing a mounting structure of a transmitter for transmitting ultrasonic waves.

FIG. 11 is a diagram illustrating a state of a reception signal of an ultrasonic wave that is received by propagating through a panel.

FIG. 12 is a diagram showing a time lapse of a voltage of a received ultrasonic signal.

FIG. 13 is a diagram illustrating sampling of a received ultrasonic signal.

FIG. 14 is a diagram showing a sampled ultrasonic signal as a reference baseline.

FIG. 15 is a diagram showing a difference between measurement sampling data with touch-on and a baseline.

FIG. 16 is a diagram illustrating the reason why a detection malfunction due to noise occurs.

FIG. 17 is a view for explaining another reason why a detection malfunction due to noise occurs.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Panel 2 Reflection element 3 Reflection array 4 Transmitter 5 Receiver 6 Detection surface 9 Object 19 A / D converter 21 SRAM (Static random
Access memory) 23 CPU 25 ROM 26 Microprocessor 31 Stylus 32 Pointed end 33 Bar-shaped part

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-61-239322 (JP, A) JP-A-54-27726 (JP, A) JP-A-1-116723 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G06F 3/03-3/033 G01S 13/00-13/95 H01H 35/00 H03K 17/74-17/98

Claims (2)

(57) [Claims] An ultrasonic wave transmitted from a transmitter is transmitted in an X direction and a Y direction of a panel, and a receiver is provided for receiving the ultrasonic wave, and there is an object absorbing the ultrasonic wave propagating on the panel. Alternatively, in an ultrasonic detection device for detecting a position, reference level detection for detecting whether or not the level of an ultrasonic signal via the receiver has exceeded a predetermined reference level indicating the presence of an object that absorbs the ultrasonic wave Means, first reference time detection means for determining whether or not the level of the ultrasonic signal exceeding the reference level detected by the reference level detection means has continued for a first reference time or more; When it is detected that the level of the ultrasonic signal exceeding the reference level detected by the first reference time detecting means has continued for the first reference time or more, the touch-on indicating the presence of the object is detected. Means for outputting an ultrasonic signal, and whether or not the level of the ultrasonic signal exceeding the reference level detected by the first reference level detecting means has continued for a second reference time shorter than the first reference time. Second reference time detecting means for judging whether or not the level of the ultrasonic signal exceeding the reference level continues for at least a second reference time by the second reference time detecting means. Means for outputting a touch-off signal indicating absence of the object when there is no such object. 2. When the first reference time detecting means detects that the level of the ultrasonic signal exceeding the reference level continues for a first reference time or more, the signal passes the reference level. 2. The ultrasonic detecting apparatus according to claim 1, further comprising a coordinate calculating means for calculating the X or Y coordinate from an average of the first time point and the second time point.