JPS60153237A - Infrared-ray remote control receiving circuit - Google Patents

Abstract

PURPOSE:To output the 2nd input signal with priority by simple costitution by providing a signal switching circuit for stopping the operation of a detecting circuit detecting the 1st input signal by the input of the 2nd input signal and outputting the 2nd input signal. CONSTITUTION:A photodetecting signal detected by a photodetecting element 8 is inputted to a pre-amplifier 16 as the 1st input signal. The amplifier 16 incorporating a filter discriminates the receiving signal and inputs its output to a comparator in a peak value detecting circuit 2. The comparator 18 is connected to a peak holding capacitor C22 and a comparator 24 for switching the charging/discharging of the C22. The output of the comparator 18 is supplied to a current operating part 26 and the output of the operating part 26 is supplied to a waveform shaping circuit 12 and also supplied as the control input of the comparator 24. If the 2nd input signal with priority is supplied to a terminal 30, a signal switching circuit 28 controls the operation of the comparator 24, drops the threshold level of the comparator 18, stops the operation of the comparator 24, releases the operation of the circuit 2, and supplies the 2nd input signal to the circuit 12 with priority.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an infrared remote control receiving circuit, and particularly to priority switching between a received signal and other input signals.

Conventionally, in an infrared remote control receiving circuit, the only input signal is a remote control signal sent from a transmitter, and the signal is detected, shaped into a waveform, and output as a control signal. For example, when this infrared remote control receiving circuit is used to operate a TV receiver, it is inconvenient to operate only by remote control, and it is also necessary to operate the TV receiver by directly touching it.

In such a case, it is necessary to adjust between the manual input signal and the remote control signal, and the former operation signal is generally given priority.

FIG. 1 shows a conventional infrared remote control receiving circuit. A signal discrimination circuit 4 is installed before the detection circuit 2 that detects the received light signal, which discriminates the first and second signals when they arrive at the same time, and gives priority to one of them and applies it to the detection circuit 2. There is. That is, the signal discrimination circuit 4 is provided with a first input terminal 6A to which a first input signal is applied, and a second input terminal 6B to which a second input signal is applied. A light receiving element 8 that converts received infrared rays into an electrical signal is installed between the first input terminal 6A and the power supply terminal 10.

The output of the detection circuit 2 is waveform-shaped by the waveform shaping circuit 12 and then taken out from the output terminal 14 as a control output.

Conventionally, in an infrared remote control receiving circuit, in order to distinguish one of two types of input signals and take it out with priority, it is necessary to
Since the signal discrimination circuit was required, its configuration was complicated.

This invention enables two
The purpose of this invention is to provide an infrared remote control receiving circuit that enables system signal discrimination.

The present invention includes a detection circuit that detects a first input signal, and a signal switching circuit that cancels the detection output of the first input signal by a second input signal and outputs the second input signal. It is characterized by

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.

FIG. 2 shows an embodiment of the infrared remote control receiving circuit of the present invention, and the same parts as those of the infrared remote control receiving circuit shown in FIG. 1 are given the same reference numerals.

In FIG. 2, the light receiving element 8 is installed between the power supply terminal 1o and the input terminal 6 of the preamplifier 16, and in this embodiment,
In this case, the light reception signal of the light receiving element 8 is the first input signal. This preamplifier 16 has a built-in filter (not shown), and this filter functions as a tuning circuit.
Discriminate the received signal.

The output of this preamplifier 16 is input to a detection circuit 2 composed of a peak 414 detection circuit, and the detection circuit 2 detects its peak value. In this detection circuit 2, a first comparator 18 is installed as a detection comparator at the front stage thereof,
A peak-bold capacitor 22 is connected between the external terminal 20 of the comparator 18 and the power supply terminal 1o. In order to switch between charging and discharging the capacitor 22, a second comparator 24 is installed as a charging/discharging comparator.

The output of the comparator 18 is applied to a current calculation unit 26, and its calculation output is applied to the waveform shaping circuit 12 and serves as a control input for the comparator 24.

A signal switching circuit 28 is installed in the detection circuit 2. That is, the second input signal to be given priority is applied to the input terminal 30. Based on this input signal, the signal switching circuit 2B controls the operation of the comparator 24 to lower the threshold level of the comparator 18, thereby stopping its operation, canceling the operation of the detection circuit 2, and simultaneously A second input signal is applied to the waveform shaping circuit 12 from the output side of the detection circuit 2.

According to such a configuration, when the second input signal arrives, the detection operation of the first input signal is canceled and at the same time, the second input signal can be shaped and extracted. Therefore,
Without installing a discrimination circuit for discriminating between the first and second input signals, the circuit configuration can be simplified and the reliability of the signal selection operation can be improved.

FIG. 3 shows a specific example of the circuit configuration of the infrared remote control receiving circuit of the present invention, and the same parts as in the embodiment shown in FIG. 2 are denoted by the same reference numerals. In this example, a constant current circuit 34 is installed which supplies a predetermined constant current to the waveform shaping circuit 12 which also serves as a detection circuit &2 and an output circuit. .42
and resistors 44 and 46.

The detection circuit 2 is provided with a first comparator 18 composed of a pair of transistors 50.
A transistor 56 as a constant current source for setting an operating current is installed on the emitter side of 52, and the base of this transistor 56 is commonly connected to transistors 35 and 38.

A signal input is applied from the amplifier 16 to the input terminal 17 formed at the base of the transistor 50 of the comparator 18, and between the external terminal 20 formed at the base of the transistor 52 and the positive power supply line. is connected to a capacitor 22 that holds the peak value of the input signal.

The comparator 18 also includes first, second, third, and fourth current inversion circuits 58, 60 as current detection means for detecting and extracting current for detecting a current based on an input signal.
．． 62.64 is added.

The first current inversion circuit 58 includes transistors 70, 72 .
73 and a resistor 74. transistor 73
For example, it is set so that a current equivalent to 1/2 of the current flowing through the transistor 70 flows, and the current flowing through the transistor 50 is detected.

The second current inversion circuit 60 includes transistors 76, 78 .
80, and detects the current flowing through the transistor 73.

The third current inversion circuit 62 includes transistors 82, 83 .
84, 85 and a resistor 86, the transistor 52
The current flowing through the circuit is detected. Further, the fourth current inverting circuit 64 includes transistors 88, 89, and 90, and detects the current flowing through the transistor 84.

The transistor 80 of the second current inversion circuit 60 and the transistor 85 of the third current inversion circuit 62 have a common collector, and are connected between the positive power supply line and the common line. These transistors 80.85 and transistors 94.96 forming a switching circuit.
and resistors 98, 100, and 102 constitute the current calculation section 26.

The output of this current calculation section 26 is applied to the second comparator 24 and compared with a reference comparison voltage. The second comparator 24 is composed of transistors 106 and 108, and a transistor 113 is connected between the emitter of the transistor 106 and 10B and the positive power supply line as a constant current source for flowing a reference current. A base current is applied to the base of this transistor 113 from the constant current circuit 34 .

At the base of transistor 106 is a diode 114 .
A reference voltage formed by the voltage division of 116, 118 and resistor 120 is applied, and the collector of transistor 108 is connected to the common line. Also, transistor 1
06 is connected to the transistor 5 of the comparator 118.
Connected to 20 base.

The signal switching circuit 28 includes a transistor 122.1.
24.126.128 and resistance 130.132.134
．． 136.138. transistor 12
2 constitutes a switching circuit that controls the comparator 24 to lower the threshold level of the comparator 18 and stop its operation based on a second input signal applied to the input terminal 30; .126.12
8 constitutes a signal input circuit that applies a second signal to the waveform forming circuit 12.

The waveform shaping circuit 12 includes transistors 142, 144,]
46, 148, 150 and a capacitor 154 connected to the outer node 152. A load 156 to be controlled is connected between the output terminal 14 and the power supply terminal 10, and the common line side terminal 15J3 is connected to a reference potential point.

Based on the above configuration, its operation will be explained with reference to the operation waveforms shown in FIG.

In FIG. 4, A is the first input signal applied to the input terminal 17, and B is the second input signal applied to the input terminal 30.

When the first input signal AI is applied to the input terminal I7, its peak value is detected by the detection circuit 2, and the charging/discharging waveform of the capacitor 22 becomes CI shown in FIG. 4C.

Next, as shown in FIG. 4B, when the second input signal arrives, the transistor 122 performs a switching operation, so that the current flowing from the transistor 106 to the capacitor 22 and the transistor 89 is affected by the second input signal. In response, the terminal voltage of capacitor 22 is reduced to a low level. In this case, the peak detection operation of the first input signal is stopped, and the capacitor 22 is charged and discharged at a low level based on the second input signal, resulting in waveforms C2 and C3.

As a result, the output of the current calculation section 26 has a waveform as shown in the fourth diagram. In addition, since the second input signal is applied to the output side of the detection circuit 2, the waveform El% shown in FIG.
As shown in E2 and E3, after the second input signal arrives, the second human input signal is applied to the waveform shaping circuit 2,
The waveform shaped output is a pulse waveform F l shown in FIG.
, , F 2 , F 3 and are added to the load 156.

Then, when the second input signal is released and the first signal arrives, the first input signal is detected again, and after predetermined waveform processing is applied to the load 156 as a control output.

According to such a configuration, the second input signal can be extracted with priority over the first input signal, and two systems of signal discrimination can be realized without requiring a complicated signal discrimination circuit.

In this embodiment, the threshold level of the comparator 18 is lowered by the second input signal, and the detection operation is canceled even when the first input signal arrives, so that the noise output from the input terminal 17 is also reduced. can be prevented at the same time.

In the embodiment, the comparison operation of the comparator 18 is stopped in this way, but a switching circuit is installed to cancel the detection output of the first input signal based on the second input signal, and at the same time, the waveform shaping is performed. A similar effect can be expected even if a second input signal is added to the circuit 12.

As explained above, according to the present invention, the detection operation of the first signal is stopped by the second signal, and at the same time, the detection operation of the first signal is stopped.
Since the second signal is generated, the second signal can be output with priority using an extremely simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional infrared remote control receiving circuit, FIG. 2 is a block diagram showing an embodiment of the infrared remote control receiving circuit of the present invention, and FIG. 3 is a specific example of the infrared remote control receiving circuit of the present invention. FIG. 4 is a circuit diagram showing an example of a typical circuit configuration, and FIG. 4 is an explanatory diagram showing its operating waveforms. 2...Detection circuit, 28...Signal switching circuit.

Claims (2)

[Claims] (1) Equipped with a detection circuit that detects the first input signal and a signal switching circuit that cancels the detection output of the first input signal in response to the second input signal and outputs the second input signal. An infrared remote control receiving circuit featuring: (2) The signal switching circuit, based on the second input signal,
2. The infrared remote control receiving circuit according to claim 1, wherein the threshold level of the comparator of the detection circuit is lowered to stop the detection operation.