JPH0260101B2 - - Google Patents

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, waveform-shaped, 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 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. Detection circuit 2 that detects the received light signal
A signal discriminating circuit 4 is installed at the front stage of the detector circuit 4 for discriminating the first and second input signals when they arrive at the same time and applying one of them to the detection circuit 2 with priority. That is, the signal discrimination circuit 4 receives the first input signal from the first input terminal 6A and the second input signal from the second input terminal 6A.
is applied through the input terminal 6B of the . Input terminal 6
A light-receiving element 8 that converts received infrared rays into an electrical signal is installed between it and a power terminal 10.

The output of the detection circuit 2 is the output of the waveform shaping circuit 1.
After the waveform is shaped in step 2, it is taken out from the output terminal 14 as a control output.

Conventionally, infrared remote control receiving circuits required a signal discrimination circuit to discriminate one of two types of input signals and take it out with priority, resulting in a complex configuration.

Therefore, an object of the present invention is to provide an infrared remote control receiving circuit that simplifies the priority switching between two input signals. A light receiving element 8 that generates a level signal corresponding to the infrared rays, and a capacitor 22 that should hold the peak value of the level signal obtained by this light receiving element.
and a first comparator 18 that includes a differential pair that receives the peak value held in the capacitor and the level signal, and generates a current depending on the magnitude relationship between the peak value and the level signal; A pulse generating means (pulse generating section 26) generates a pulse according to the current obtained by the first comparator, and a second pulse generating means generates a current by comparing the pulse generated by the pulse generating means with a reference level. a comparator 24, a current combining means (current inversion circuit 64) that combines the currents generated in the first and second comparators to control charging and discharging of the capacitor, and an input other than the level signal. a signal switching circuit 28 that receives a signal, stops the operation of the second comparator according to the input signal, and outputs the input signal; The waveform shaping circuit 12 receives the input signal, shapes the waveform, and outputs the waveform.

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 10 and the input terminal 6 of the preamplifier 16,
The light receiving element 8 receives infrared rays for remote control, and obtains a level signal corresponding to the received infrared rays. That is, this level signal is the first input signal. Preamplifier 1 receiving this input signal
Reference numeral 6 has a built-in filter (not shown), which functions as a tuning circuit and discriminates received signals.

The output of this preamplifier 16 is input to a detection circuit 2 composed of a peak value detection circuit, and the detection circuit 2 detects its peak value. This detection circuit 2
A first comparator 18 is installed as a detection comparator in the front stage thereof, and a peak hold capacitor 22 is connected between the external terminal 20 of this comparator 18 and the power supply terminal 10. There is. 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 pulse generator 26, and the output thereof 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, a second input signal different from the first input signal is applied to the input terminal 30, and this second input signal is an input signal that should be given priority over the level signal obtained on the light receiving element 8 side. Based on this second input signal, the signal switching circuit 28 controls the operation of the comparator 24 to lower the threshold level of the comparator 18, thereby stopping its operation and changing the operation of the detection circuit 2. At the same time, the second input signal is applied to the waveform shaping circuit 12 from the output side of the detection circuit 2.

With 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 signal discrimination circuit for discriminating between the first and second input signals, the circuit configuration can be simplified and the reliability of the signal priority selection operation can be improved.

Next, 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 given the same reference numerals.

In FIG. 3, this embodiment includes a detection circuit 2
A constant current circuit 34 is installed to supply a predetermined constant current to the waveform shaping circuit 12 which also serves as an output circuit. This constant current circuit 34 includes transistors 35,
36, 40, 42 and resistors 44, 46.

The detection circuit 2 includes a pair of transistors 50, 5.
A first comparator 18 consisting of a transistor 50 and a transistor 56 as a constant current source for setting an operating current is installed on the emitter side of the transistors 50 and 52.
is installed, and the base of this transistor 56 is commonly connected to transistors 35 and 38.

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

Further, on the output side of the comparator 18, first, second, and third current inversion circuits 58 are provided as current detection means for detecting and extracting a current based on an input signal.
60 and 62 are installed, and a fourth current inverting circuit 64 is installed as a current combining means.

The current inversion circuit 58 includes transistors 70, 7
2, 73 and a resistor 74. The transistor 73 is set so that a current corresponding to 1/2 of the current flowing through the transistor 70 flows, and detects the current flowing through the transistor 50.

The current inversion circuit 60 includes transistors 76, 7
8 and 80, and detects the current flowing through the transistor 73.

The current inversion circuit 62 includes transistors 82, 8
3, 84, 85 and a resistor 86, and detects the current flowing through the transistor 52.

Further, the current inverting circuit 64 includes a transistor 8
8, 89, and 90, and constitute a current combining means that combines the currents of the comparators 18 and 24 to control charging and discharging of the capacitor 22.

The transistor 80 of the current inversion circuit 60
and the transistor 85 of the 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, transistors 94, 96 and resistors 98, 100, 10 that constitute a switching circuit
2 constitutes a pulse generating section 26. Therefore, the pulse generator 26 obtains a pulse corresponding to the current obtained by the comparator 18.

The output of this pulse generator 26 is applied to a comparator 24 and compared with a reference comparison voltage. Comparator 2
4 is composed of transistors 106 and 108,
A transistor 113 is connected between the emitters of the transistors 106 and 108 and the positive power supply line as a constant current source for flowing a reference current, and a base current is supplied to the base of the transistor 113 from a constant current circuit 34. Added. Diodes 114 and 11 are connected to the base of the transistor 106.
6, 118, and a reference voltage formed by the voltage division of resistor 120 is applied to transistor 108.
The collectors of are connected to a common line. Further, the collector of the transistor 106 is connected to the comparator 1
It is connected to the base of the transistor 52 of No. 8.

The signal switching circuit 28 then switches the transistor 1
22, 124, 126, 128 and resistor 130,
It is composed of 132, 134, 136, and 138. The transistor 122 forms a switching circuit that controls the comparator 24 to lower the threshold level of the comparator 18 and stop its operation based on the second input signal applied to the input terminal 30. ,126,128
constitutes a signal input circuit that applies the second input signal to the waveform shaping circuit 12.

The waveform shaping circuit 12 includes transistors 142,1
44, 146, 148, 150 and external terminal 15
It consists of a collector 154 connected to 2. A load 156 to be controlled is connected between the input terminal 14 and the power supply terminal 10, and a terminal 158 on the common line side 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 _A1 is applied to the input terminal 17, its peak value is detected by the detection circuit 2, and the charging/discharging waveform of the capacitor 22 is shown in FIG. 4C.
It becomes C ₁ .

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 absorbs the influence of the second input signal. In response, the terminal voltage of capacitor 22 is reduced to a low level. In this case, the peak value 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 C ₂ and C ₃ .

As a result, the output of the pulse generator 26 has a waveform as shown in FIG. 4D. Furthermore, since the second input signal is applied to the output side of the detection circuit 2,
As shown in the waveforms E ₁ , E ₂ , and E ₃ of Fig. 4E, the second
After the input signal arrives, a second input signal is applied to the waveform shaping circuit 12, and its waveform shaping output becomes pulse waveforms F ₁ , F ₂ , F ₃ shown in FIG. 4F, applied to 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 the second input signal can be extracted with priority over the first input signal.
System 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. Noise output can also be blocked 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, a switching circuit is installed to cancel the detection output of the first input signal. circuit 12
A similar effect can be expected even if a second input signal is applied to.

As explained above, according to the present invention, when another input signal that should be prioritized is added to the level signal obtained on the light receiving element side by infrared rays for remote control, priority switching of that input signal is performed. This can be done with a simple configuration without installing a conventional signal discrimination circuit, and the reliability of signal switching can be improved.

[Brief explanation of drawings]

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. FIG. 4 is a diagram showing operating waveforms of the infrared remote control receiving circuit shown in FIG. 2... Detection circuit, 8... Light receiving element, 12... Waveform shaping circuit, 18... First comparator, 22... Capacitor, 24... Second comparator, 26... Pulse generator (pulse 28... signal switching circuit, 64... current inverting circuit (current combining means).

Claims (1)

[Scope of Claims] 1. A light-receiving element that receives infrared rays for remote control and generates a level signal corresponding to the infrared rays; A capacitor that holds the peak value of the level signal obtained by this light-receiving element; and This capacitor. a first comparator comprising a differential pair that receives the peak value held in the level signal and the level signal, and generates a current according to the magnitude relationship between the peak value and the level signal; a second comparator that generates a current by comparing the pulse generated by the pulse generating means with a reference level; and the first and second comparators. current synthesizing means for synthesizing currents generated in the comparators to control charging and discharging of the capacitor; and receiving an input signal different from the level signal and operating the second comparator in accordance with the input signal. a signal switching circuit that stops the input signal and outputs the input signal; and a waveform shaping circuit that receives the pulse generated by the pulse generating means or the input signal applied from the signal switching circuit, shapes the waveform, and outputs the signal. An infrared remote control receiving circuit.