JPH07114441A - Touch panel device - Google Patents

Abstract

PURPOSE:To improve the S/N without being affected by large external disturbance light by a small optical signal level in a touch panel device using the transmission/reception of the optical signal. CONSTITUTION:A carrier generated by a carrier generator 1 is modulated at a modulator 2 by a pulse signal generated by a contact operation by the operator, the modulated signal is converted into an optical signal by a light emitting element 3 and the optical signal is outputted, a light receiving element 5 receives the optical signal via an infrared ray filter 4 and converts the optical signal into an electric signal. A synchronization detector 9 receives the electric signal and applies synchronization detection to the electric signal by using the carrier generated by the carrier generator 1 via a delay device 8 as a switching signal. A waveform shaping device 7 applies wavefrom shaping to the detection output to convert into a pulse, which is outputted. The delay device 8 compensates a phase delay generated in a path from the modulator 2 to the light receiving element 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical touch panel device capable of transmitting a human instruction by simply touching the screen of a display.

[0002]

2. Description of the Related Art In recent years, the number of operation switches has become enormous due to other functionalization and systemization of equipment, which makes it difficult to use. In order to solve this problem, a touch panel device that can input a request by simply touching an icon displayed on the screen is a computer terminal, an in-vehicle audiovisual device as one of means for considering compactness and operability. Widely used in input devices such as.

A conventional touch panel device will be described below with reference to the drawings. FIG. 3 is a block diagram showing the functions of a conventional optical touch panel device. In the figure, 1 is a carrier wave generator that generates a stable carrier wave, 2 is a modulator that modulates the carrier wave output by the carrier wave generator 1 with pulses, and 3 is light emission that converts the modulated wave output by the modulator 2 into an optical signal. An element 4, an infrared filter that blocks visible light components of an input optical signal, 5 a light receiving element that converts the optical signal that has passed through the filter 4 into an electrical signal, and 6 an envelope of the electrical signal output by the light receiving element 5. An envelope detector for line detection, and a waveform shaper 7 for shaping the detection output of the envelope detector 6.

Explaining the mutual relation and operation of the above-mentioned components, the modulator 2 multiplies the pulse of the modulation signal by the carrier wave output from the carrier wave generator 1 to obtain ASK (Amplitude).
(Sift Keing) signal is generated. The ASK signal is converted into an infrared light signal by the light emitting element 3, passes through the operation surface, and then passes through the infrared filter 4 for blocking visible light and is sent to the light receiving element 5. The optical signal is converted into an electric signal by the light receiving element 5, envelope-detected by the envelope detector 6, and then shaped into a pulse by the waveform shaper 7. Here, the reason why the pulse is adopted as the modulation signal is to improve the noise resistance property against the ambient light. Note that the SN ratio can be further increased by encoding the signal.

In the configuration in which the pulse of the modulation signal is turned off when the touch panel switch (not shown) is operated,
When the touch panel switch is not operated, infrared light is intermittently output from the light emitting element 3, so the waveform shaper 7
Outputs a pulse signal, the infrared light is not output from the light emitting element 3 when the touch panel switch is operated. Therefore, it is possible to determine whether the touch panel operation is on or off depending on the presence or absence of the output of the waveform shaper 7.

[0006]

In such a conventional touch panel device, in the case where sunlight reaching up to 100,000 lux is used, if the infrared filter 4 has a high transmittance, the light receiving element 5 is saturated. In addition, if the low transmittance filter is used, it becomes impossible to secure a desired minimum light receiving sensitivity, and it becomes very difficult to secure stable operation as a touch panel device. To solve this problem,
Although it is a reality that the structure of the optical system and the mechanism system is devised so that sunlight or the like does not directly irradiate the light receiving element 5, a satisfactory result cannot be obtained yet.

The present invention solves the above problems, and an object of the present invention is to provide a touch panel device which operates stably even under adverse conditions such as the irradiation of ambient light such as sunlight.

[0008]

In order to achieve the above object, the present invention provides a carrier wave generator for stably generating a carrier wave, and a modulator for modulating the carrier wave by a modulation pulse generated by a touch operation of an operator. A light emitting element that converts a modulated wave output by the modulator into an optical signal and outputs the signal, an infrared filter that blocks a visible light component in the path of the optical signal, and an optical signal that passes the optical signal through the filter. A light receiving element for converting and outputting, a delay device for inputting and delaying the carrier wave from the carrier wave generator, a switching signal for the carrier wave output by the delayer, and a synchronous detection for the output signal of the light receiving element. A synchronous detector and a waveform shaper for shaping the detected output into a pulse are provided, and the delay device corrects the phase delay of the signal generated in the path from the modulator to the light receiving element. It is the touch panel device.

[0009]

According to the present invention, in the above structure, the modulator modulates the carrier wave generated by the carrier wave generator with the pulse signal generated by the touch operation of the operator, and the light emitting element outputs the modulated signal as an optical signal, and the infrared filter. The light receiving element converts an optical signal input via the light receiving element into an electric signal. The synchronous detector inputs the carrier wave as a synchronizing pulse from the carrier wave generator through the delay device, and synchronously detects the signal obtained by the light receiving element.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A touch panel device according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of this embodiment. It should be noted that the same components as those of the conventional example are given the same reference numerals and detailed description thereof will be omitted. The difference of the present embodiment from the configuration of the conventional example is that the delay detector 8 is provided and a synchronous detector 9 is provided instead of the envelope detector.

The operation of the above configuration will be described. An operation in which the carrier wave generator 1 generates a stable carrier wave, the modulator 2 multiplies a pulse input for modulation and the carrier wave to generate an ASK modulated wave, and the modulated wave is converted into an optical signal by the light emitting element 3. Is the same as the conventional example. Also, the process in which the optical signal reaches the infrared filter 4 after passing through the operation surface, the visible light component is removed and the light signal is input to the light receiving element 5 and converted into an electric signal is the same as the conventional example. In the present embodiment, in order to detect this electric signal, a synchronous detector 9 is used instead of the envelope detector used in the conventional example. In synchronous detection, detection is performed by multiplying a carrier wave and a signal. In order to obtain this carrier wave, the carrier wave is obtained from the carrier wave generator 1 through the delay device 8 and supplied to the synchronous detector 9. The delay device 8 is provided to delay the phase of the carrier wave corresponding to the delay of the phase of the modulation signal reproduced by the light receiving element 5.

The operation of the synchronous detector will be described below with reference to the drawings. 2A is a circuit diagram showing a configuration of a synchronous detector using a multiplier having a differential amplifier as a constituent element, and FIG. 2B is a waveform diagram showing waveforms at respective parts of the multiplier. Is. In the figure, the transistor Q
3 and the transistor Q6 constitute a differential amplifier having a constant current source in the common emitter circuit, the amplitude-modulated wave output from the light receiving element 5 is applied to the transistor Q3, and the current obtained by amplifying the input is connected to the transistor Q3. Transistor Q6
Flow to the collectors in opposite phase to each other. Also, the transistors Q1 and Q2, and the transistor Q
4 and a transistor Q5 form a differential amplifier, the collectors of which are connected to a common load resistor R1 and R2, and the common emitter circuit includes a transistor Q3 and a transistor Q6. The output current of the differential amplifier flows as an emitter input.

On the other hand, the transistor Q1 and the transistor Q
4, and switching signals for synchronous detection are input to the transistors Q2 and Q5 in opposite phases to each other. As described above, these switching signals are carriers input from the carrier generator 1 through the delay unit 8, and each differential amplifier alternately switches the emitter current to one of the two transistors by the saturation operation. Is input at a sufficiently large level to perform switching operation, and equivalently serves as a switching signal input. It should be noted that if switching is simply performed, it is possible to use only the transistor Q3 and the differential amplifiers Q1 and Q2, but in order to prevent the switching signal component from being included in the detection output, another transistor Q6 and a differential amplifier are used. Using amplifiers Q4 and Q5, each output is connected to a common load resistor R
The switching signal components are canceled by combining with 1 and R2, and this configuration is also suitable for integration into an integrated circuit. For example, when the current of the transistor Q1 is increased by one switching signal input of the pair of signals whose phases are opposite to each other, the current of the transistor Q5 is decreased by the other switching signal input, and the combined current value in the common load resistor R2 hardly changes. . The same applies to the combined current of the transistors Q2 and Q4. This means that the waveform of the switching signal is not output to the load resistance.

On the other hand, a differential amplifier Q for inputting a modulated wave signal
As for the output of 3.Q6, as shown in the waveform 7 of FIG. 2B, the waveforms of the upper half of the modulated wave are combined and output. This operation is, for example, as shown in FIG.
When the phase relationship between the modulation signal and the switching signal is set so that the transistor Q1 conducts when the current of the transistor Q3 increases, the signal opposite in phase of the transistor Q6 is blocked by the transistor Q5 and the load resistance R
Since it does not appear in 2, it is not offset. Therefore, the base input of the transistor Q1 and the base input of the transistor Q1 are in phase relationship with the base input of the transistor Q3 shown by the waveform 1 in FIG. 2B, and the collector current of the transistor Q1 is positive as shown in the waveform 3. It becomes a half-wave current. In other words, only the current of the transistor Q3 flows through the load resistor R2, and the current of the transistor Q6 is cut off. Further, in the above phase relationship, the phase relationship between the current of the transistor Q6 and the current of the transistor Q5 also becomes the same phase relationship, and from the relationship of the base inputs shown in the waveform 4 and the waveform 5, the positive relationship of the transistor Q6 Only half waveform is load resistance R2
Flow to. Since the waveform 3 and the waveform 6 are the waveforms obtained by differentially amplifying the modulated signal input, they have a phase difference of 180 degrees from each other. It is obtained as a waveform. This is exactly the detection output.

When this synchronous detector 9 is used, since it is a double-wave rectification, it is more efficient than envelope detection, and a signal obtained by synthesizing a large converted voltage by direct light and a converted voltage of a small optical signal is enveloped. As in the case of detection, the desired signal is not cut by a large detection bias, and by this means, the S / N ratio is improved by about 20 dB, and the signal may be made smaller by that amount. Sufficient results can be obtained even when the signal level is lowered when an infrared filter having a transmittance is used to directly block light.
As described above, according to this embodiment, since the S / N ratio can be improved by synchronously detecting the received signal, there is an effect that a signal can be transmitted / received with a stable operation at a small signal level even in the presence of ambient light.

[0016]

As is apparent from the above embodiments, the present invention provides a carrier wave generator that stably generates a carrier wave, and a modulator that modulates the carrier wave by a modulation pulse generated by a touch operation of an operator. A light emitting element that converts the modulated wave output by the modulator into an optical signal and outputs the signal, an infrared filter that blocks visible light components in the path of the optical signal, and an optical signal that passes through the filter to an electrical signal. And a light receiving element for outputting as a carrier wave from the carrier wave generator,
A delay device for delaying and outputting, a switching signal for the carrier wave output by the delay device, a synchronous detector for synchronously detecting the output signal of the light receiving element, and a waveform shaper for shaping the detected output into a pulse The delay device is a touch panel device configured to correct the phase delay of the signal generated in the path from the modulator to the light receiving element,
Since the / N ratio can be improved, there is an effect that a signal can be transmitted and received with a stable operation at a small signal level even in the presence of ambient light.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a touch panel device according to an embodiment of the present invention.

FIG. 2A is a circuit diagram showing a circuit configuration of a synchronous detector in a touch panel device according to an embodiment of the present invention. FIG. 2B is a waveform diagram showing waveforms of respective parts in the touch panel device according to an embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a conventional touch panel device.

[Explanation of symbols]

 1 Carrier wave generator 2 Modulator 3 Light emitting element 4 Infrared filter 5 Light receiving element 6 Envelope detector 7 Waveform shaper 8 Delay device 9 Synchronous detector

Claims (1)

[Claims] 1. A carrier wave generator that stably generates a carrier wave, a modulator that modulates the carrier wave by a modulation pulse generated by a touch operation of an operator, and a modulated wave output by the modulator is converted into an optical signal. A light emitting element that outputs the light signal, an infrared filter that blocks a visible light component in the path of the optical signal, a light receiving element that converts the optical signal that has passed through the filter into an electric signal and outputs the electric signal, and a carrier wave from the carrier wave generator. A delay device that inputs, delays and outputs, a carrier signal that the delay device outputs, a switching signal, a synchronous detector that synchronously detects the output signal of the light receiving element, and a waveform shaper that shapes the detection output into pulses. And a delay unit for correcting a phase delay of a signal generated in a path from the modulator to the light receiving element.