JPH0830377A - Touch panel device - Google Patents

Abstract

PURPOSE:To provide a touch panel device with which an intended touch is discriminated from a foreign object stuck on a touch surface and proper processing can be conducted. CONSTITUTION:First of all, waveform data at non-touch time are possessed in a memory 13 and their contents are stored in a reference memory 16 as an initializing operation. Concerning a normal position detecting operation, a differential waveform generating part 17 calculates the difference between new received signal waveform data and the contents stored in the reference memory 16 and outputs it as differential waveform data. When any touch operation is performed in this case, the differential waveform data show a positive value at a correspondent part near a touch position. A touch width calculating part 18 compares the differential waveform data with a previously decided threshold level and when data exceeding the threshold level exist, a range T of those data is outputted to a touch kind judging part 19 as touch width. The touch kind judging part 19 judges whether the detected state is caused by the touch of a finger or the touch of something excepting for the finger and outputs the result to a touch position calculating part 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a touch panel device utilizing surface acoustic waves.

[0002]

2. Description of the Related Art A conventional touch panel device is disclosed in Japanese Patent Application Laid-Open No. 61-61
-239322, a surface acoustic wave of a constant intensity emitted intermittently from the transmitting piezoelectric element is branched into a plurality of paths by the surface acoustic wave reflection array, crosses the touch detection area, and is opposed to another surface acoustic wave. The wave reflection array again collects the light in one path to reach the receiving piezoelectric element. At this time, the reception signal level output from the reception piezoelectric element is determined by the physical propagation characteristics of the path from the transmission piezoelectric element to the reception piezoelectric element.

In the first place, the touch operation with a finger has the effect of attenuating surface acoustic waves. Therefore, when the touch operation is performed on the touch detection area (hereinafter, referred to as “when touching”), when the touch operation is not performed (hereinafter,
Compared with "when not touched"), the propagation attenuation on the path increases and the received signal level decreases. As described above, in the conventional touch panel device, when the received signal level is lower than the value measured in advance, it is determined that the touch operation is performed in the touch detection area, and the touch position on the touch surface is calculated. are doing.

[0004]

However, when such a conventional touch panel device is used, foreign matter adhering to the touch surface due to saliva, precipitation, or the like is propagated through the touch detection area. Since it has an effect of attenuating, the touch surface is considered to have been touched and the same processing as a normal touch operation with a finger is performed. This has been a serious cause of malfunction of the conventional touch panel device.

As described above, the conventional touch panel device has a problem that a foreign substance causes a malfunction, and further, in order to avoid the problem, a usage environment of the conventional touch panel has to be strictly selected.

Therefore, the present invention solves such a problem, and an object of the present invention is to provide a touch panel device capable of discriminating a foreign substance adhering to a touch surface from an intentional touch and performing an appropriate process. There is a place to do it.

[0007]

A touch panel device according to the present invention includes a touch surface for transmitting a surface wave, a surface wave generating means for generating a surface wave on the touch surface, and an intensity of the surface wave on the touch surface. Having a surface wave detecting means for detecting,
In a touch panel device that detects a touch on the touch surface from the intensity change of the surface wave on the touch surface, and calculates the touch position on the touch surface, the intensity change of the surface wave on the touch surface to the touch surface. And a touch type determining unit that identifies the type of touch on the touch surface from the time variation of the touch width.

[0008]

【Example】

(Embodiment 1) FIG. 1 is a block diagram showing an embodiment of the present invention. The operation of this embodiment is roughly divided into a transmitting operation, a receiving operation, and a position coordinate calculating operation. Hereinafter, each operation will be described in detail.

First, the transmission operation will be described.

In accordance with the transmission control signal 21 from the control section 15, the transmission section 7 sends out a burst piezoelectric element drive signal as shown in FIG. According to the piezoelectric element switching signal 22, the transmission switching unit 8 transmits a piezoelectric element driving signal to the piezoelectric element 2 when detecting the Y coordinate and to the piezoelectric element 3 when detecting the X coordinate. The piezoelectric elements 2 and 3 convert the piezoelectric element drive signal into a surface acoustic wave and propagate it on the touch surface 1. The surface acoustic wave emitted from the piezoelectric element 2 is reflected by each reflection element of the reflection element group 6a by 90 degrees, traverses the touch surface 1, and is reflected again by 90 degrees by the reflection element group 6b to reach the piezoelectric element 5. . Similarly to this, the piezoelectric element 3
The surface acoustic wave emitted from reaches the piezoelectric element 4 through the reflecting element groups 6c and 6d.

Next, the receiving operation will be described.

The piezoelectric elements 4 and 5 convert the reached surface acoustic wave into an electric signal again, and output a reception signal as shown in FIG. 2 (b). It should be noted that FIG. 2B shows a waveform when there is no touch. The reception switching unit 9 selects and outputs the reception signal from the piezoelectric element 5 when detecting the Y coordinate and the reception signal from the piezoelectric element 4 when detecting the X coordinate according to the piezoelectric element switching signal 22. The amplification unit 10 amplifies the signal from the reception switching unit 9, removes a noise component, and then outputs the signal to the detection unit 11. The detection unit 11 detects and rectifies the signal from the amplification unit 10, and outputs the envelope signal shown in FIG. The AD converter 12 converts the envelope signal from the detection unit 11 into digital data according to the sampling control signal 23, and stores the result in the memory 13.

The position coordinate calculation operation includes an initialization operation for obtaining the characteristics of the panel when not touched and a position detection operation for detecting the touched position.

In the initialization operation, as shown in FIG. 3A, the reception signal level data at the time of non-touch is acquired in the memory 13 and the contents thereof are stored in the reference memory 16. It is desirable that such an initialization operation be performed regularly or when an abnormal state occurs.

In the position detection operation, the transmission operation and the reception operation are performed at least once, and new reception signal level data is acquired in the memory 13. After acquiring the data, the differential signal generation unit 17
Takes the difference between the received signal level data stored in the memory 13 and the contents stored in the reference memory 16, and outputs the difference signal level data. Here, memory 1 when not touched
Since the data stored in 3 is substantially the same as the data stored in the reference memory 16, the differential signal level data has a value of about zero or a noise level. On the other hand, when the touch operation is performed on almost the central portion of the touch surface 1, the received signal level data as shown in FIG. 3B is stored in the memory 13, so that the differential signal level data is shown in FIG. It becomes like c).

As shown in FIG. 3C, the touch width calculating section 18 compares the difference signal level data with a predetermined threshold level, and if there is data exceeding the threshold level, the range T of the data is set. The touch width is output to the touch type determination unit 19. As shown in FIG. 4, a range T'exceeding the threshold level may be calculated using linear interpolation or the like and used as the touch width.

The touch type determination unit 19 determines whether the detected state is a touch with a finger or a touch other than the finger according to a determination method described later, and outputs the result to the touch position calculation unit 21.

The touch position calculation unit 21 determines the peak of the difference signal level data or the zero cross point that appears when the difference signal level data is differentiated as the touch position, and outputs it to the host computer together with the output from the touch type determination unit 19. To do.

Next, a touch type determination method will be described.

As described above, the touch panel device using surface acoustic waves has a problem that it is determined that there is a touch even in a case other than the touch operation by the finger. A typical example of this is a malfunction caused by liquid droplets.

Therefore, the change in the touch width between the case where the finger is intentionally touched and the case where the water droplet is attached was measured. FIG. 5A is a diagram showing a touch with a finger, and FIG. 5B is a diagram showing variations in the touch width when a water droplet is attached. In the case of touching with a finger, it increases almost monotonically after the touch is started, and remains almost constant after 100 msec from the start of the touch. On the other hand, when a water drop adheres, it increases sharply after the touch is started, and then increases and decreases toward a constant state.

From the above, it is possible to distinguish whether the surface acoustic wave is attenuated intentionally by the finger or by the water droplet by analyzing the change in the touch width after the touch is started.

Therefore, in the touch type judging section 19, as shown in FIG.
When the touch width becomes larger than zero, that is, when the touch is started, a predetermined number of touch width data are sequentially stored in the touch width data memory 20, as shown in FIG. If the touch width data becomes zero before the predetermined number is stored, the data storage operation is restarted from the beginning as an abnormal state.

When a predetermined number of data are stored, the data in the touch width data memory 20 is taken out in chronological order, and if the change shows a monotonically increasing tendency, it is touched by the finger. It is judged as a touch by.

(Embodiment 2) FIG. 7 is a block diagram showing another embodiment of the present invention.

In this structure, the piezoelectric elements 101 to 1 for transmission are used.
24 and the receiving piezoelectric elements 201 to 224 are paired with each other, and the surface acoustic waves emitted from the respective transmitting piezoelectric elements are arranged so as to reach the respective receiving piezoelectric elements forming a pair.

First, the transmission operation will be described.

In accordance with the transmission control signal 21 from the control unit 15, the transmission unit 7 outputs a piezoelectric element drive signal as shown in FIG. 8A to the transmission switching unit 8. According to the piezoelectric element switching signal 22, the transmission switching unit 8 sequentially transmits the piezoelectric element driving signal to the piezoelectric elements 101 to 112 when detecting the X coordinate and to the piezoelectric elements 113 to 124 when detecting the Y coordinate. The piezoelectric elements 101 to 124 convert the piezoelectric element drive signal into a surface acoustic wave and propagate it on the touch surface 1.

Next, the receiving operation will be described.

The piezoelectric elements 201 to 224 convert the reached surface acoustic waves into electric signals again. The reception switching unit 9 sequentially selects the reception signals from the piezoelectric elements 201 to 212 when detecting the X coordinate and the reception signals from the piezoelectric elements 213 to 224 when detecting the Y coordinate according to the piezoelectric element switching signal 22. The received signal as shown in 8 (b) is output. Note that FIG.
(B) is a waveform when not touched. The amplification unit 10 amplifies the signal from the reception switching unit 9, removes a noise component, and then outputs the signal to the detection unit 11. The detector 11 is the amplifier 1
The signal from 0 is detected and rectified, and the envelope signal shown in FIG. 8C is output. The AD converter 12 converts the envelope signals of the piezoelectric elements 201 to 224 into digital data according to the sampling control signal 23, and stores the result in the memory 13.

The position coordinate calculation operation includes an initialization operation for obtaining the characteristics of the panel when not touched and a position detection operation for detecting the touched position. In addition, in order to simplify the description, the following description will be given using the X coordinate as an example.

In the initialization operation, as shown in FIG. 9A, the reception signal level data at the time of non-touch is acquired in the memory 13, and the contents are stored in the reference memory 16. It is desirable that such an initialization operation be performed regularly or when an abnormal state occurs.

In the position detection operation, the transmission operation and the reception operation are performed at least once for each piezoelectric element pair, and new reception signal level data is acquired in the memory 13. After acquiring the data, the differential signal generation unit 17 takes the difference between the received signal level data stored in the memory 13 and the content stored in the reference memory 16, and outputs the differential signal level data. Here, the data stored in the memory 13 when not touched is
Since the data is almost the same as the data stored in the reference memory 16, the difference signal level data has a value of zero or a noise level. On the other hand, if the touch operation is performed on almost the central portion of the touch surface 1, FIG.
The received signal level data as shown in FIG.
3, the differential signal level data is stored in FIG.
It becomes like (c).

As shown in FIG. 9C, the touch width calculator 18 compares the difference signal level data with a predetermined threshold level, and if there is data exceeding the threshold level, the range T of the data is determined. The touch width is output to the touch type determination unit 19. Note that, as shown in FIG. 10, a range T'exceeding the threshold level may be calculated using linear interpolation or the like and used as the touch width.

The touch type determination unit 19 determines whether the detected state is a touch with a finger or a touch other than the finger according to the determination method described in the first embodiment, and sends the result to the touch position calculation unit 21. Output.

The touch position calculation unit 21 determines the peak of the differential signal level data or the zero cross point that appears when the differential signal level data is differentiated as the touch position, and outputs it to the host computer together with the output from the touch type determination unit 19. To do.

In this embodiment, the transmission / reception operation is sequentially performed for each piezoelectric element pair, but it may be performed in parallel for a plurality of piezoelectric element pairs.

[0038]

As described above, in the touch panel device of the present invention, the touch width on the touch surface is calculated from the intensity change of the surface acoustic wave generated by the touch on the touch surface, and the touch width is changed by time. Foreign matter adhering to the surface, in particular, a pseudo touch operation caused by a water droplet and an intentional touch operation performed by a finger are discriminated from each other, and stable touch detection without malfunction can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a waveform diagram of the piezoelectric element drive signal, the reception signal, and the reception signal after detection in FIG.

FIG. 3 is a diagram showing an example of received signal waveform data in FIG. 1 and a touch width calculation method.

FIG. 4 is a diagram showing another touch width calculation method in FIG. 1.

FIG. 5 is a diagram showing an example of a change over time in the touch width depending on the touch type.

FIG. 6 is a flowchart of a determination method for determining a touch type from a touch width.

FIG. 7 is a block diagram showing another embodiment of the present invention.

8 is a waveform diagram of the piezoelectric element drive signal, the reception signal, and the reception signal after detection in FIG.

9 is a diagram showing an example of received signal waveform data in FIG. 8 and a touch width calculation method.

10 is a diagram showing another touch width calculation method in FIG.

[Explanation of symbols]

 1: Touch surface 2-5, 101-124, 201-224: Piezoelectric element 6: Reflective element group 7: Transmission section 8: Transmission switching section 9: Reception switching section 11: Detection section 12: AD converter 13: Memory 14: CPU 15: Control unit 16: Reference memory 17: Difference waveform generation unit 18: Touch width calculation unit 19: Touch type determination unit 20: Touch width data memory 21: Touch position calculation unit

Claims (1)

[Claims] 1. A touch surface for transmitting a surface wave, a surface wave generating means for generating a surface wave on the touch surface, and a surface wave detecting means for detecting the intensity of the surface wave on the touch surface. In a touch panel device that senses a touch on the touch surface from a change in the intensity of a surface wave on the touch surface and calculates a touch position on the touch surface, a change in the intensity of the surface wave on the touch surface to the touch surface is performed. A touch panel device comprising: a touch width calculating means for calculating a touch width; and a touch type determining means for specifying a touch type on the touch surface based on a change over time of the touch width.