JPS6314559B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a system for, for example, a remotely controllable television receiver, in which the television receiver itself determines the presence or absence of a remote control signal, and displays an audio output indicating that a remote control signal has been received. In particular, the purpose is to eliminate transient noise in circuits that operate.

FIG. 1 shows a block diagram of the above circuit. In the figure, a is a signal from a remote device and is output from the transmitter 1. The signal a enters a receiver 2 on the receiver side, is further amplified by an amplifier 3, and is applied to a signal processing circuit 4. Based on the output of the signal processing circuit 4, channel switching, volume adjustment, etc. are performed. On the other hand, the signal from the amplification section 3 is applied to a buffer and waveform conversion circuit 5, where it is converted into a pulse with a constant width.
It is added as a control signal for the oscillation circuit 6. The output of this oscillation circuit 6 is applied to the audio circuit 7 in parallel with the television audio signal b, and is further input to the speaker 8. As a result, when the remote control signal is input, a sound is output from the speaker 8, and it can be confirmed that the remote control signal has been input.

In FIG. 1, the transmitting section 1, the receiving section 2, the amplifying section 3, the signal processing circuit 4, and the audio circuit 7 are already known, so their explanation will be omitted.

FIG. 2 shows specific examples of the buffer/waveform conversion circuit 5 and oscillation circuit 6 that were proposed prior to the present invention. Further, FIG. 3 shows a waveform diagram for explaining the operation. In FIG. 2, resistors 9 and 12 and transistor 11 constitute an emitter follower circuit, which serves as a buffer circuit. Resistor 10 is transistor 1
1 protection resistor. Capacitor 13 is an integrating capacitor, and its discharge time is determined by resistors 12 and 14. transistor 16,
The resistor 15 is a waveform shaping circuit, and the polarity is further reversed by the transistor 17. Resistor 18, 19, 20, 21, capacitor 2
2, 23 and transistors 24, 25 constitute an astable multivibrator. The resistor 26 is an output resistor, and the capacitor 27 is for DC cut, both of which are selected to eliminate the influence of the audio circuit 7 in the subsequent stage.

In FIG. 2, the signal of FIG. 3a passing through transistor 11 is integrated by integrating capacitor 13. In FIG. This waveform is shown in Figure 3b. The discharge time constant of this capacitor 13 is determined by the resistors 12 and 14. The integrated signal is transferred to transistor 16
is added to the base of the signal and is inverted and amplified (Figure 3c).
Further, the collector output of the transistor 16 is connected to the base of the transistor 17 and inverted and amplified to improve the sharpness of the waveform. The collector output of this transistor 17 is shown in FIG. 3d. The collector of the transistor 17 is connected to one end of the output resistor 26 of the oscillation circuit 6.

With this configuration, when a signal from a remote device comes in, the collector of transistor 17 goes high as shown in FIG. 3d. Since the collector of transistor 17 is connected to the base of transistor 25, the base of transistor 25 will be at a low level in the absence of a remote control signal. Therefore, the astable multivibrator becomes stable and oscillation stops. On the other hand, when there is a remote control signal, the transistor 17 becomes non-conductive, and the astable multivibrator starts oscillating, producing a pulse train of about 3 KHz with a constant time width. This signal is superimposed on the television audio signal and output from the speaker 8.

By the way, FIG. 2 has the following drawbacks.

When there is a remote control signal, transistor 17 is turned off, but due to the leakage current of the transistor,
In addition to affecting the oscillation frequency, the load resistance 2
I can't even lower 6 too much. It also has the disadvantage of producing transient noise when the remote control signal is lost.

The present invention obviates the above drawbacks. An example of this is shown in FIG. 4 below. With this configuration, the oscillation circuit 6 is always off and oscillates only when a remote control signal is input, so there is no need to worry about oscillation leakage. Furthermore, compared to the circuit shown in FIG. 2, one transistor is not required, resulting in cost reduction. Further, there are advantages such as being advantageous against transient sounds.

4 will be explained below along with the waveform diagram of FIG. 5. 4 differs from FIG. 2 in that transistor 17 is removed and the collector of transistor 16 is directly connected to the emitter of transistor 24.

Next, its operation will be explained.

First, when the remote control signal is not input, in this case, the base of transistor 11 is at a low level, so the emitter of transistor 11 and the base of transistor 16 are also at low level, transistor 16 is cut off, and its collector is at high level. become the level. As a result, transistor 24
When the emitter voltage becomes larger than the base voltage, it becomes cut-off. Therefore, the astable multivibrator stops oscillating.

On the other hand, when a remote control signal is input, both the base and emitter of transistor 11 and the base of transistor 16 become high level, transistor 16 is turned on, and its collector becomes low level. Therefore, at this time, the astable multivibrator starts oscillating. In this way, by controlling the emitter of the transistor 24, the oscillation frequency can be stabilized,
Further, the value of the load resistor 26 can also be reduced to some extent.

Next, the transient sound at the falling edge of the remote control signal will be explained using FIG. Now, assume that the base of the transistor 24 is at a high level (≈V _BE ).
At this time, if the remote control signal is cut off, the base of the transistor 16 changes from high level to low level, so the collector of transistor 16 changes from low level to high level. At this time, the base of the transistor 24 is 0.7V as shown in Figure 5a.
However, since the transistor 16 is turned off, the emitter of the transistor 24 rises as shown in FIG. 5b. The V _BE voltage of transistor 24 then decreases, and at some point transistor 24 turns off. When the transistor 24 is turned off, the emitter of the transistor 24 is in an open state, and the collector voltage of the transistor 24 is
The 5th is transmitted from the base of 4 to the collector.
The level becomes high as shown in Figure c.

By the way, the base of the transistor 25 is charged up from the negative direction as shown in FIG. 5d, and when the transistor 24 is off, it is still
Assume that it has not reached 0.7V. At this time, when the transistor 24 is turned off, the collector of the transistor 24 becomes a high level, and therefore the base of the transistor 25 also becomes a high level, and the transistor 25 is turned on. Therefore, the base of the transistor 25 becomes 0.7V, which remains constant thereafter. At this time, the collector of the transistor 25 becomes low level,
The base of transistor 24 drops momentarily. However, at this point, the emitter voltage of the transistor 24 continues to rise, so the transistor 24 is off, and this variation in the base voltage of the transistor 24 is transmitted to the collector of the transistor 24. Therefore, the collector voltage of transistor 24 drops momentarily, but if there is enough voltage to turn on transistor 25, the base of transistor 25 maintains a constant voltage _VBE . Note that the base voltage of the transistor 24, which momentarily dropped, continues to rise due to the time constant of the resistor 19 and capacitor 22.

Therefore, transient noise occurs at the base and collector of transistor 24, but not at the base of transistor 25. Therefore, no transient sound is generated from the speaker 8.

As explained above, according to the present invention, in a buffer/waveform conversion circuit for connecting a received signal from a remote control device to an audio circuit in parallel with a television audio signal, the output end of the waveform shaping circuit is By connecting the emitter of one transistor of the vibrator and the base of the other transistor of the astable multivibrator to the audio circuit, the oscillation frequency of the astable multivibrator can be made stable; It is also possible to prevent the generation of transient sounds when the remote control signal is cut off.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a remote control device including a response device of the present invention, FIG. 2 is a specific circuit diagram of a response device proposed prior to the present invention, and FIG. 3 is a diagram for explaining the operation of FIG. A waveform diagram, FIG. 4 is a specific circuit diagram of a remote control response device in an embodiment of the present invention, and FIG.
This figure is a main part voltage waveform diagram for explaining the operation of FIG. 4. 9, 12, 11... Resistor and transistor forming the buffer circuit, 13... Integrating capacitor,
16... Inverting amplification transistor, 24, 25...
...A transistor that constitutes an astable multivibrator.

Claims (1)

[Claims] 1 The remote control signal from the remote control device is passed through a waveform conversion circuit and an oscillation circuit in sequence, and connected to the audio circuit in parallel with the television audio signal so that the operation of the controlled device in response to the remote control operation can be confirmed by audio. In the device configured as above, the waveform conversion circuit and oscillation circuit are composed of a waveform shaping circuit and an astable multivibrator, the output terminal of the waveform shaping circuit is connected to the emitter of one transistor of the astable multivibrator, and the astable A remote control response device characterized in that the base of the other transistor of the multivibrator is connected to an audio circuit.