JPH09168190A - Identification circuit for remote control signal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a remote control receiving part from being affected by the power noises and the external noises. SOLUTION: The output of a regulator 10 is supplied to a 1st input amplifier 2 as the power voltage Vcc'. The regulator 10 is connected to a power supply Vcc having a constitution common to that of the next stage of the amplifier 2. In such a constitution, the influences of the superimposed noises of the supply Vcc and the external noises can be eliminated even when the noises of the frequency band that can pass through a BPF 4 are superimposed on the supply Vcc or an LED 1 applies the photoelectric conversion to the external noises in addition to the remote control signal. Thus the accurate remote control is attained in response to the instruction of the remote control signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention, when a remote control receiving unit built in an electronic device such as a TV receiver receives a remote control signal, the remote control receiving unit erroneously decodes the remote control signal and, as a result, the electronic signal is received. The present invention relates to a remote control signal identification circuit that prevents a device from malfunctioning.

[0002]

2. Description of the Related Art At present, most electronic devices such as TV receivers and VTRs have a remote control function (remote control function). FIG. 3 is a circuit block diagram showing a general remote control receiver, which is incorporated in the electronic device in an integrated state. In FIG. 3, (1) is a light receiving diode, which receives a remote control signal generated from a wireless remote controller (not shown) provided outside the electronic device and photoelectrically converts it into an electric signal. Here, the remote control signal is a signal obtained by intermittently combining a specific frequency (for example, 38 KHz) for an arbitrary time (for example, several tens of μsec), and depending on this combination, a plurality of operations set in the electronic device can be performed. You can control. (2) is a first-stage first input amplifier, which amplifies the current flowing through the light-receiving diode (1) to amplify the amplitude of the remote control signal. (3) is the second input amplifier of the next stage,
The output of the first input amplifier (2) is further amplified. Reference numeral (4) is a band-pass filter, which filters out a specific frequency band of the remote control signal.
A detector (5) detects the output of the bandpass filter (4) and forms an envelope. (6) is a drive circuit, which has a built-in comparator (not shown) whose reference voltage is lower than the envelope voltage of the bandpass filter (4), and when the envelope voltage is higher than the reference voltage,
5V (high level) is output for the envelope generation time, and when the envelope voltage is lower than the reference voltage,
It outputs 0V (low level). The binary output of the drive circuit (6) is applied to a 5V-driven microcomputer (not shown), and remote control of the electronic device is realized based on the output of the microcomputer. still,
The power supply Vcc of the electronic device is commonly applied to the remote control receiver.

However, when the electronic device is a TV receiver, the TV receiver has a built-in horizontal oscillator for performing horizontal scanning on a cathode ray tube, and the oscillation frequency (16.6 KHz) of the horizontal oscillator is set. It will be superimposed on the power line as noise. Then, the superimposed noise is
And the second input amplifiers (2) and (3) are amplified while being superimposed on the remote control signal. After that, since the superposed noise (16.6 KHz) is close to the specific frequency (38 KHz) of the remote control signal, it is attenuated to an amplitude smaller than the specific frequency of the remote control signal, but passes through the bandpass filter (4). Where the bandpass filter (4)
The amplitude of the superimposed noise that has passed through is caused by the amplification factors of the first and second input amplifiers (2) and (3), and the detector (5)
If the detection level is exceeded, an extra envelope will be formed in the portion where the superimposed noise occurs. As a result, the output of the drive circuit (6) originally becomes 0V, but becomes 5V, which causes a problem that the electronic device malfunctions.

Therefore, in order to solve the above problem, it is sufficient to devise a method in which the power source noise is not applied to the power source input of the first stage first input amplifier (2). FIG. 4 shows an example in which the above-mentioned device is applied, and FIG. 5 shows another example. In FIG. 4, (7)
Is the remote control receiver, which is an integration of the entire configuration of FIG. Reference numeral (8) is a smoothing capacitor, which is connected between the power supply Vcc and the ground, and when the oscillation frequency of the horizontal oscillator is superimposed on the power supply Vcc as noise, the superimposed noise is smoothed to remove the noise. It is appropriate that the smoothing capacitor (8) has a capacitance of about 10 μF.

Further, in FIG. 5, (9) is an integrated regulator, which regulates the power supply Vcc to newly generate a power supply voltage Vcc 'for the remote control receiver (7). Here, even if the superposed noise occurs in the power supply Vcc, the power supply Vcc and the remote control receiver (7)
Since the regulator (9) is interposed between and, the power supply voltage Vcc 'is not affected by the superimposed noise.

As described above, the smoothing capacitor (8) or the regulator (9) is provided for the entire remote control receiving section (7) to remove the superimposed noise of the power source Vcc.

[0007]

However, when the measures shown in FIGS. 4 and 5 are taken, it is necessary to add an external component to the integrated circuit which constitutes the remote control receiver (7). However, there is an unavoidable problem that the mounting board for the integrated circuit and the external parts is increased in size and the cost of the entire structure is increased.

In particular, as shown in FIG. 5, the output of the regulator (9) is supplied to the power supply voltage Vc for the entire remote control receiver (7).
In the case of the configuration in which C'is supplied, the following problems occur. Power supply Vcc which is the input / output of the regulator (9)
The relationship between the power supply Vcc ′ and the power supply Vcc ′ is inevitably lower than the power supply voltage Vcc due to the configuration of the regulator (9) (for example, the power supply Vcc is 4.5 V to 5.5 V).
In the case of V, the power supply Vcc 'is usually set to 4 V or less). As a result, the first remote controller receiver (7)
Since the power supply voltage of the second and second input amplifiers (2) and (3) becomes smaller than that in the case of FIG. 3, the dynamic range of the first and second input amplifiers (2) and (3) is less than the originally required range. Resulting in. Under these circumstances, if external noise is also projected together with the remote control signal to the light receiving diode (1) provided in front of the first and second input amplifiers (2) and (3), the second input amplifier The S / N of (3) decreases, that is, the maximum amplitude of the signal component (corresponding to the remote control signal) and the noise component (corresponding to external noise) output from the second input amplifier (3). The difference from the maximum amplitude becomes small. In the worst case, the maximum amplitude of the signal component and the noise component output from the second input amplifier (3) may be equal and the difference between them may become zero.
Further, the detection level of the detector (5) is also lowered. here,
When the frequency of the external noise is in the frequency band that can pass through the bandpass filter (4), the noise component is the first
Also, since the detection level of the detector (5) is reached as the S / N of the second input amplifiers (2) and (3) decreases, it is detected by the detector (5) via the bandpass filter (4). I will end up.
That is, an extra envelope is formed in the portion where the external noise is generated, which is not related to the portion where the remote control signal is generated. As a result, the drive circuit (6) outputs 5V where it should have originally output 0V, which causes a problem that the microcomputer malfunctions. That is, there is a problem that correct remote control cannot be realized.

Therefore, according to the present invention, the remote control receiver (7) is provided.
An object of the present invention is to provide a remote control signal identification circuit that can correctly identify a remote control signal without taking measures such as providing a smoothing capacitor (8) and a regulator (9) for the whole.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and is characterized in that it has a predetermined frequency and is generated intermittently for a predetermined time. At least one stage input amplifier for receiving a remote control signal for controlling the operation of the device, a band filter for extracting the predetermined frequency band from the output of the input amplifier, a detector for detecting the output of the band filter, and the detector. A drive circuit for generating a drive signal for controlling the operation of the electronic device corresponding to the remote control signal based on the output of the controller, and a remote control signal identification circuit, the power supply voltage for the input amplifier The point is that a regulator that outputs is provided.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be specifically described with reference to the drawings. FIG. 1 is a circuit block diagram showing the present invention. The same components as those in FIG. 5 are designated by the same reference numerals and the description thereof will be omitted. The entire configuration of FIG. 1 is integrated.

In FIG. 1, reference numeral (10) is a regulator, and a power input of the regulator (10) has a second input amplifier (3), a bandpass filter (4), a detector (5) and a drive circuit (6). The power supply Vcc of 1) is commonly applied. The voltage output from the regulator (10) is the first
It is supplied to the power supply input of the input amplifier (2) as the power supply Vcc '.

When the electronic device incorporating the remote control receiver is a TV receiver, the oscillation frequency (16.6 KHz) of the horizontal oscillator is superimposed on the power supply Vcc as noise, but the power supply Vcc 'is the power supply. The effect of noise does not appear. As a result, the first input amplifier (2) in the first stage is supplied with the power supply Vcc 'which is the output of the regulator (10) to perform the amplification operation, and the second input amplifier (3) in the next stage passes through the regulator (10). The power supply Vcc itself, which is not supplied, is applied to perform the amplification operation. Here, the first stage first
Since the power supply noise of the input amplifier (2) is reliably suppressed, only the amplification factor of the second input amplifier (3) at the next stage becomes a problem for the superimposed noise of the power supply Vcc. However, in comparison with the case where the power supply noise is conventionally amplified by the product of the amplification factors of the first and second input amplifiers (2) and (3), in the embodiment of the present invention, the power supply noise is Since it is amplified only by the second input amplifier (3), the amplitude of the power supply noise at the output point of the second input amplifier (3) is very small compared to the conventional one. Therefore, the power supply noise output from the second input amplifier (3) does not reach the detection level of the detector (5) even when passing through the bandpass filter (4). Further, the detector (5) has a power source Vcc.
Therefore, the level itself for detecting the pass output of the bandpass filter (4) does not decrease. From the above, it is possible to eliminate the influence of power supply noise, obtain a normal output of the detector (5) and an output of the drive circuit (6) according to the content of the remote control signal, and realize normal remote control.

Even when external noise is generated during the projection of the remote control signal and the light receiving diode (1) photoelectrically converts both the remote control signal and the external noise on the same time axis. , The second input amplifier (3) is connected to the power supply Vcc and performs an amplification operation, so that a sufficient dynamic range can be secured at the output point of the second input amplifier (3) and a sufficient S / N can be secured. In other words, the difference between the maximum amplitude of the signal component and the maximum amplitude of the noise component at the output point of the second input amplifier (3) can be made larger than in the conventional case. At this time, the detection level of the detector (5) does not decrease. As described above, it is possible to eliminate the influence of external noise, obtain a normal output of the detector (5) and a normal output of the drive circuit (6) according to the content of the remote control signal, and realize normal remote control.

Therefore, as described in the embodiment of the present invention, the regulator (10) is operated by the power source Vcc, and the first input amplifier (2) is operated by the output of the regulator (10), that is, the power source Vcc '. As a result, even if the power supply Vcc ′ becomes lower than the power supply Vcc,
The influence of power supply noise and external noise can be eliminated, and reliable remote control can be realized. Further, by integrating the circuit block diagram of FIG. 1, external parts are not required, and it is possible to prevent an increase in the size of the mounting board and an increase in the cost of the entire structure which have occurred conventionally.

FIG. 2 is a circuit block diagram showing a specific example of the regulator (10). In FIG. 2, (11)
Is a reference voltage source, which is connected to a power source Vcc to operate. (12) (13) is the power supply V which is the regulated output
A resistor connected in series between cc 'and ground. (1
4) and 15) are differentially connected NPN type transistors, the base of the transistor (14) is connected to the output of the reference voltage source (11), and the base of the transistor (15) is resistors (12) (13). ), The common emitter of the transistors (14) and (15) is connected to the current source (1
It is grounded via 6). Reference numeral (17) is a PNP type transistor whose base is connected to the collector of the transistor (14), whose emitter is connected to the collector of the transistor (15), and whose collector is connected to one end of the resistor (12). That is, the emitter-collector path of the transistor (17) is inserted between the power supply lines of the power supply Vcc and the power supply Vcc '.

In FIG. 2, when the power supply Vcc changes,
The emitter voltage of the transistor (17) changes and the bias of the transistor (17) changes. For example, when the power supply Vcc rises, the collector-emitter voltage of the transistor (17) decreases and the resistors (12) (13)
The connection point voltage of rises. Then, the transistor (1
The collector current of 5) increases, and the emitter current of the transistor (17) is shunted toward the collector of the transistor (15). As a result, the emitter voltage of the transistor (17) drops and the power supply voltage Vcc drops. When the power supply voltage Vcc drops, the operation reverse to the above operation. From the above, by controlling the bias of the transistor (17) according to the fluctuation of the power supply voltage Vcc, the power supply voltage Vcc
cc 'is held constant. In addition, the power source Vcc and the power source V
Since the collector-emitter voltage of the transistor (17) is always generated between cc 'and
cc 'is lower than the power supply Vcc.

[0018]

According to the present invention, the regulator is operated by the power supply of the electronic device and the input amplifier of the first stage is operated by the output of the regulator, so that the regulator output is lower than the power supply. It is possible to eliminate the influence of power supply noise and external noise and realize reliable remote control. Further, since the present invention is suitable for integration, external parts are not required, and it is possible to obtain an advantage that it is possible to prevent an increase in the size of the mounting board and an increase in the cost of the entire structure, which have occurred conventionally.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing an identification circuit of a remote control signal of the present invention.

FIG. 2 is a circuit block diagram showing a specific example of FIG.

FIG. 3 is a circuit block diagram showing a conventional circuit.

FIG. 4 is a circuit block diagram showing an example of a conventional circuit.

FIG. 5 is a circuit block diagram showing another example of a conventional circuit.

[Explanation of symbols]

 (2) First input amplifier (3) Second input amplifier (4) Band filter (5) Detector (6) Drive circuit (10) Regulator

Claims (3)

[Claims] 1. An at least one-stage input amplifier which receives a remote control signal for controlling the operation of an electronic device, which has a predetermined frequency and is intermittently generated for a predetermined time, and the predetermined frequency band from the output of the input amplifier. A band-pass filter for extracting the output of the band-pass filter, a wave detector for detecting the output of the band-pass filter, and a drive circuit for generating a drive signal for controlling the operation of the electronic device corresponding to the remote control signal based on the output of the wave detector. ,
A remote control signal identification circuit, comprising a regulator for outputting a power supply voltage for the input amplifier. 2. The remote control signal identification according to claim 1, wherein when the input amplifiers are connected in a plurality of stages, the output voltage of the regulator is supplied to the power input of the input amplifier in the first stage. circuit. 3. The power supply voltage for the input amplifier, the bandpass filter, the wave detector, and the drive circuit connected to the subsequent stage of the first stage input amplifier and the power supply voltage for the regulator are common. The remote control signal identification circuit according to claim 2.