JP2002169648A - Ultrasonic touch panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize, in an ultrasonic touch panel of a compact and simple construction, lower power consumption and a faster operation. SOLUTION: In the ultrasonic touch panel which a plurality of ultrasonic transducers 2 of which roller screen like electrodes Tn, Rn are formed on the surface of piezoelectric ceramic thin plate composed of piezoelectric material are opposed and provided on the surface of one side of a non-piezoelectric substrate 3, and which propagation paths for surface acoustic wave are disposed on so that the paths mutually intersect with, if a finger 4 comes into contact with the non-piezoelectric substrate, by shifting, with a selection circuit 5, to a partial scanning mode that limitedly selects the roller screen like electrodes Tn, Rn corresponding to the indicated position of the finger 4 and its adjoining area, it becomes possible to lower the power consumption and accelerate the position output in the ultrasonic touch panel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic touch panel provided with an ultrasonic transmission / reception device on a non-piezoelectric substrate to detect contact of a finger or an object with the non-piezoelectric substrate.

[0002]

2. Description of the Related Art As a conventional ultrasonic touch panel, a method using a surface acoustic wave has been widely used.

Conventional methods using surface acoustic waves include a method of indirectly exciting a non-piezoelectric substrate such as glass by a wedge transducer using a bulk wave oscillator.
A method of directly exciting with a piezoelectric thin film transducer may be used.

[0004]

In a system using a wedge-shaped transducer using a bulk wave oscillator, a non-piezoelectric substrate is indirectly excited and a surface array is provided by a reflection array arranged around the non-piezoelectric substrate. Since the wave is reflected twice, the loss of the surface acoustic wave is large, and it is necessary to set the driving voltage of the transducer high, which makes it difficult to reduce the power consumption.

A piezoelectric thin film transducer is a method in which a piezoelectric thin film such as ZnO is vapor-deposited on a substrate and surface acoustic waves are excited by interdigital electrodes. The piezoelectric thin film transducer is used as a high-frequency device because it exhibits various transmission characteristics due to the configuration of the interdigital electrodes. , UHF and VHF bands, the signal processing circuit and the like become complicated, and it is difficult to reduce power consumption.

An object of the present invention is to provide an ultrasonic touch panel having a simple configuration, low power consumption and excellent efficiency.

[0007]

Means for Solving the Problems As means for solving the above-mentioned problems, as a first configuration, a plurality of ultrasonic transducers having interdigital electrodes formed on the surface thereof are opposed to one surface of the non-piezoelectric substrate, And, the propagation paths of the surface acoustic waves propagating between the opposed ultrasonic transducers are provided so as to intersect with each other, and a pair is selected by a selection circuit from among the interdigital transducers of the opposed ultrasonic transducers, In an ultrasonic touch panel for detecting the position of a finger or an indicator from attenuation of surface acoustic waves propagating between interdigital electrodes, when the finger or the indicator is in contact with a non-piezoelectric substrate, the finger or the indicator is From the detection result of the pointing position of the container, the selection circuit selects an interdigital electrode corresponding to the pointing position and an area adjacent to the pointing position, and Select the region adjacent to the fine the indicated position to constitute a ultrasonic touch panel so as to have a partial scan mode to scan.

As a means for solving the above-mentioned problem, as a second configuration, a plurality of ultrasonic transducers each having interdigital electrodes formed on the surface thereof face one surface of the non-piezoelectric substrate. Propagation paths of surface acoustic waves propagating between the ultrasonic transducers are provided so as to intersect with each other, and a pair of interdigital transducers of the ultrasonic transducer facing each other is selected by a selection circuit, and propagated between the interdigital transducers. In the ultrasonic touch panel that detects the position of a finger or an indicator from the attenuation of surface acoustic waves, a pair of comb-shaped electrodes arranged so that arc-shaped electrode fingers are interposed between them is formed by an ultrasonic wave. At least one transducer is arranged at one corner of one surface of the non-piezoelectric substrate, and another ultrasonic transducer on the receiving side is disposed from the ultrasonic transducer. Has a scanning mode for detecting the presence or absence of contact between the finger or indicator and the non-piezoelectric substrate from the attenuation of surface acoustic waves emitted against, and has detected contact between the finger or indicator and the non-piezoelectric substrate. In this case, the ultrasonic touch panel is configured so that the selection circuit selects the IDT corresponding to the detection portion and starts detecting the position of the finger or the indicator.

As a means for solving the above-mentioned problems, a third configuration is such that, in addition to the second configuration, the presence or absence of contact between a finger or an indicator and a non-piezoelectric substrate is detected, and Or, after calculating the pointing position of the indicator once, the partial scanning mode in which the selection circuit selects the interdigital electrode corresponding to the pointing position of the finger or the indicator and the area adjacent to the pointing position, and has a surface elasticity. The ultrasonic touch panel is configured to calculate the designated position from the attenuation of the wave.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the ultrasonic touch panel according to the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing the first embodiment.

Reference numeral 1 denotes an ultrasonic touch panel main body. 2a
2d are interdigital electrodes T on the surface of a piezoelectric material such as PZT.
This is an ultrasonic transducer in which n and Rn are formed. Reference numeral 3 denotes a non-piezoelectric substrate made of glass, acrylic, or the like and serving as a transmission path for surface acoustic waves. Reference numeral 4 denotes a finger for inputting a designated position. In this embodiment, the finger is used as the object for indicating the position. However, similarly to the finger, it is also possible to use an indicator such as a stylus pen or a cursor accompanied by attenuation of the surface acoustic wave when the non-piezoelectric substrate contacts. It is.

FIG. 2 is a perspective view showing the actual shape of the IDT. The interdigital transducer 11 is formed of a metal thin film such as aluminum, is formed on the surface of a piezoelectric ceramic thin plate 12 composed of a piezoelectric material such as PZT, and the electrode fingers of the interdigital transducer 11 transmit the wavelength of the ultrasonic wave to be transmitted or received. Are formed in a comb-tooth shape with an electrode cycle length determined in accordance with. The interdigital transducer 11 is formed by a pair of comb-shaped electrodes having electrode fingers interposed therebetween.

FIG. 3 shows a variation of the shape of the ultrasonic transducer. In the configuration of the ultrasonic touch panel shown in FIG. 1, the ultrasonic transducers 2 a to 2 d are formed so as to include a plurality of interdigital electrodes. A plurality of small ultrasonic transducers may be arranged in the direction.

FIG. 4 shows a circuit block configuration of the ultrasonic touch panel. 2 is an ultrasonic transducer, 5 is an ultrasonic transducer and a selection circuit for selecting an interdigital transducer included in the ultrasonic transducer, and 6 generates an electric signal having a frequency corresponding to the electrode cycle length of the interdigital transducer. A pulse generator 7 is a signal processing circuit;
The electric signal converted by the ultrasonic transducer on the receiving side is subjected to processes such as rectification, smoothing, and amplification, and a signal corresponding to the attenuation of the surface acoustic wave is output. Reference numeral 8 denotes a comparator, which compares the output signal of the signal processing circuit with a reference voltage to determine whether or not the surface acoustic wave has been attenuated. Reference numeral 9 denotes a CPU, which controls the pulse generator, the selection circuit, and the signal processing circuit, and determines the amount of surface acoustic wave attenuation and the positions of the selected interdigital transducers Tn, Rn.
Calculate the pointing position of the finger.

FIG. 5 is a flowchart showing a scanning method of the selection circuit for selecting the interdigital electrodes Tn and Rn.

The operation of the ultrasonic touch panel will be described with reference to FIG. 1 and FIGS.

First, a case where the finger 4 is not in contact with the non-piezoelectric substrate 3 (non-contact state) will be described.

The pulse generator 6 generates an electric signal of several MHz which is a frequency corresponding to the electrode cycle length of the interdigital transducer of the ultrasonic transducer 2 and outputs it as a pulse output signal. Subsequently, the pulse output signal is input to the transmission-side ultrasonic transducer via the selection circuit 5, and is converted into a surface acoustic wave. On the other hand, the ultrasonic transducer 2 on the receiving side receives the surface acoustic wave using the non-piezoelectric substrate as a medium, converts the surface acoustic wave into an electric signal, inputs the electric signal to the signal processing circuit 7 via the selection circuit 5, and rectifies the electric signal. , Smoothing, amplifying, and comparing with a reference voltage by the comparator 8 to determine whether or not the surface acoustic wave is attenuated. When it is determined that the surface acoustic wave is less attenuated and is in the non-contact state, the entire surface scanning is started again.

Next, the operation when the finger 4 is in contact with the non-piezoelectric substrate 3 (contact state) will be described.

When the finger 4 comes into contact with the non-piezoelectric substrate 3, the surface acoustic wave output from the transmitting ultrasonic transducer is partially absorbed by the finger and attenuated compared with the surface acoustic wave in the non-contact state. The elastic wave reaches the ultrasonic transducer 2 on the receiving side. By converting the surface acoustic wave into an electric signal by the ultrasonic transducer 2 on the receiving side, inputting the electric signal to the signal processing circuit 7 via the selection circuit 5, rectifying, smoothing and amplifying, and comparing the rectified, smoothed and amplified voltage with the reference voltage by the comparator 8 Then, the presence or absence of the attenuation of the surface acoustic wave is determined. The attenuation of surface acoustic waves is large,
If it is determined that the finger is in the contact state, the entire surface of the finger is scanned in the y-axis direction to obtain the designated position in the y-axis direction, and the selected ultrasonic transducer 2 and interdigital electrodes Tn, Rn when the surface acoustic wave is attenuated. CPU 9 calculates the position indicated by the finger from the position.

Further, assuming that the interdigital electrodes corresponding to the calculation result of the pointing position of the finger 4 are Tk and Rm, for example, the interdigital electrodes Tk and Rm and the interdigital electrodes Tk-1 and Tk + in the peripheral area.
The selection (partial scanning) of 1, Rm-1 and Rm + 1 is performed in the order of the x-axis and the y-axis, and while the finger 4 contacts the non-piezoelectric substrate 3 and the attenuation of the surface acoustic wave is detected. The partial scan is repeated, and the CPU 9 calculates the pointing position of the finger from the positions of the interdigital transducers Tn and Rn of the ultrasonic transducer selected when the surface acoustic wave is attenuated.

In the case of full-surface scanning, in the first configuration of this embodiment, a maximum of 7 points in the x-axis direction is required to calculate the pointing position of the finger.
It is necessary to switch the selection circuit four times in the y-axis direction. On the other hand, in the case of partial scanning, switching of the selection circuit in each of the x-axis direction and the y-axis direction can be performed up to three times at the maximum. Therefore,
In the first embodiment, the time required to obtain the designated position of the finger once is reduced as compared with the method of performing only full-surface scanning, so that the power consumption is reduced and the number of times the designated position is output is increased. Is possible.

Next, a description will be given of a second embodiment of the ultrasonic touch panel according to the present invention.

FIG. 6 is a schematic diagram showing the configuration of the second embodiment. In the ultrasonic touch panel of the first embodiment, another ultrasonic sensor as shown in FIG. The ultrasonic transducer 2e having the same electrode cycle length as the acoustic transducer and having arc-shaped electrode fingers interposed therebetween is arranged at the corner of the upper surface of the non-piezoelectric substrate 3. In the configuration shown in FIG. 6, the fan-shaped ultrasonic transducer 2e is disposed between the interdigital transducers T1 and T11. However, depending on the attenuation characteristics of the surface acoustic wave, the interdigital transducer 2e is disposed between the interdigital transducers T7 and R11. For example, it is sufficiently possible to dispose a plurality of ultrasonic transducers at other positions or to dispose a circular ultrasonic transducer that propagates a surface acoustic wave radially.

Next, the operation of the second embodiment will be described with reference to FIG. 4 and FIGS.

FIG. 8 is a flowchart showing a scanning method in the second embodiment of the ultrasonic touch panel.

At the start of scanning, a pulse output signal having a frequency corresponding to the electrode cycle length is output from the pulse generation circuit 6 via the selection circuit 5 to the ultrasonic transducer 2e, and a surface acoustic wave is transmitted from the ultrasonic transducer 2e. You.
Next, the interdigital transducer R of the ultrasonic transducer on the receiving side
1 to 7 and R11 to R14 are sequentially selected by the selection circuit 5.

When the finger 4 comes into contact with the non-piezoelectric substrate 3, the surface acoustic wave is attenuated, and the output signal level of the ultrasonic transducer 2 on the receiving side decreases. Therefore, the comparator 8 determines the decrease in the output signal level,
The presence or absence of contact between the finger 4 and the non-piezoelectric substrate 3 can be detected.

Thereafter, the entire surface is scanned in the x-axis direction and the y-axis direction, and the positions of the interdigital transducers Tn and Rn of the ultrasonic transducer selected when the surface acoustic wave is attenuated are determined.
The CPU 9 calculates the pointing position of the finger.

In the above-described second embodiment, the number of times of selecting the non-contact ultrasonic transducer and the interdigital transducer and the number of transmissions are determined by using the transmitting ultrasonic transducer disposed at the upper corner of the non-piezoelectric substrate. Time can be reduced, power consumption can be reduced, and output of a finger pointing position can be speeded up.

Further, as a third embodiment, by performing the partial scanning shown in the first embodiment with the configuration of FIG. 6 shown in the second embodiment, an ultrasonic transducer and a blind in a contact state are performed. It is possible to further reduce the number of times of selection of the shape electrode, and it is possible to reduce the power consumption and to speed up the output of the finger pointing position.

It is to be noted that, instead of the circuit block configuration shown in FIG. 4, an ultrasonic transducer on the transmitting side and an ultrasonic transducer on the receiving side are connected to an amplifier 10 via a selecting circuit 5.
Even when the circuit block configuration shown in FIG. 9 configured as a delay line oscillator is applied, as in the first to third embodiments, it is effective in reducing power consumption and increasing the output speed of the finger pointing position. It is.

[0034]

According to the present invention, based on the calculation result of the pointing position of the finger, there is provided a partial scanning mode in which the ultrasonic scanning and the interdigital transducer corresponding to the pointing position of the finger and the surrounding area are selected only. In the configuration 1, while the finger is in contact with the non-piezoelectric substrate, it is possible to reduce power consumption or increase the number of times the designated position is output.

According to the second aspect of the present invention, in the second configuration having a scanning mode in which an ultrasonic transducer is provided at a corner on the upper surface of the non-piezoelectric substrate and the ultrasonic transducer is used as a transmitting side, While not in contact with the piezoelectric substrate, there is no need to select another ultrasonic transducer on the transmission side, and there is no need to switch the selection circuit on the transmission side, thus reducing power consumption and increasing the speed of finger pointing position output. It is effective for conversion.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of an ultrasonic touch panel according to the present invention.

FIG. 2 is a perspective view showing the arrangement of interdigital electrodes of the ultrasonic transducer.

FIG. 3 is a schematic diagram showing a configuration of an ultrasonic touch panel on which a small ultrasonic transducer is arranged.

FIG. 4 is an explanatory diagram showing a circuit block configuration of an ultrasonic touch panel.

FIG. 5 is a flowchart illustrating a scanning method of the ultrasonic touch panel.

FIG. 6 is a schematic diagram showing a configuration of an ultrasonic touch panel in which an ultrasonic transducer is arranged at a corner of a non-piezoelectric substrate.

FIG. 7 is an explanatory diagram showing an electrode shape of an ultrasonic transducer on a non-piezoelectric substrate.

FIG. 8 is a flowchart illustrating a scanning method of an ultrasonic touch panel on which an ultrasonic transducer of a non-piezoelectric substrate is arranged.

FIG. 9 connects an ultrasonic transducer and an amplifier,
FIG. 3 is an explanatory diagram illustrating a circuit block configuration of an ultrasonic touch panel configured as a delay line oscillator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Ultrasonic touch panel 2, 2a, 2b, 2c, 2d, 2e Ultrasonic transducer 3 Non-piezoelectric substrate 4 Finger 5 Selection circuit 6 Pulse generator 7 Signal processing circuit 8 Comparator 9 CPU 10 Amplifier 11 Interdigital electrode 12 Piezoelectric thin plate Tn Electrode (transmitting side) Rn IDT electrode (receiving side)

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Takafumi Sarada 1-8-8 Nakase, Mihama-ku, Chiba-shi, Chiba Inside SII IRD Center Co., Ltd. (72) Inventor Masataka Shinogi Nakase, Mihama-ku, Chiba-shi, Chiba 1-8, SII IRD Center F-term (reference) 5B068 AA02 AA03 BB21 BC14 BE01 BE06

Claims (3)

[Claims] A plurality of ultrasonic transducers each having an interdigital transducer formed on a surface thereof face one surface of a non-piezoelectric substrate;
And, the propagation paths of the surface acoustic waves propagating between the opposed ultrasonic transducers are provided so as to intersect with each other, and a pair is selected by a selection circuit from among the interdigital transducers of the opposed ultrasonic transducers, In an ultrasonic touch panel for detecting the position of a finger or an indicator from the attenuation of surface acoustic waves propagating between interdigital electrodes, when the finger or the indicator is in contact with a non-piezoelectric substrate, the finger or the indicator is A partial scanning mode for selecting, from the detection result of the pointing position of the vessel, the IDT corresponding to the pointing position and the area adjacent to the pointing position by the selection circuit, and selecting the pointing position and the area adjacent to the pointing position; Ultrasonic touch panel having a. 2. An ultrasonic transducer having interdigital electrodes formed on a surface thereof, a plurality of ultrasonic transducers facing one surface of a non-piezoelectric substrate,
And, the propagation paths of the surface acoustic waves propagating between the opposed ultrasonic transducers are provided so as to intersect with each other, and a pair is selected by a selection circuit from among the interdigital transducers of the opposed ultrasonic transducers, In an ultrasonic touch panel that detects the position of a human finger or an indicator from attenuation of surface acoustic waves propagating between interdigital electrodes, a pair of comb-shaped electrodes arranged so that arc-shaped electrode fingers are interposed between each other At least one ultrasonic transducer on which the non-piezoelectric substrate is formed is disposed at one corner of the surface of the non-piezoelectric substrate, and the person is determined from attenuation of surface acoustic waves emitted from the ultrasonic transducer to another ultrasonic transducer on the receiving side. A scanning mode for detecting the presence or absence of contact between the finger or the indicator and the non-piezoelectric substrate; If detected, in the selection circuit,
Selecting the interdigital transducer corresponding to the detection portion,
An ultrasonic touch panel that starts detecting the position of a finger or an indicator. 3. The method according to claim 1, further comprising detecting the presence or absence of contact between the finger or the indicator and the non-piezoelectric substrate, calculating the indicated position of the finger or the indicator once, and then indicating the position of the finger or the indicator and the designated position. 3. The ultrasonic touch panel according to claim 2, further comprising a partial scanning mode in which an interdigital electrode corresponding to a region adjacent to the position is selected by a selection circuit, and wherein the designated position is calculated from attenuation of surface acoustic waves.