JPS6012833B2 - Noise suppression circuit for television receiver equipped with remote control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a noise suppression circuit for a television receiver equipped with a remote control device.

Generally, when selecting a channel on a television receiver, unpleasant noise is generated from a loudspeaker or noise appears on the picture tube screen during a period of switching from one channel to another.

A conventional technique for muting such noise is disclosed in, for example, US Pat. No. 3,597,531.

In this follow-up example, auto-search tuning and muting are started using a tuning pulse, and when the motor is tuned to a broadcast channel by rotation, a synchronizing signal and video carrier are detected from the television receiver, and the output is used to deactivate the relay. The drive current for the channel switching motor is cut off and the mute switch is turned off. Therefore, in this conventional example, the overall configuration becomes complicated, as it necessarily requires means for detecting that the television receiver is in a tuned state and means for unmuting using the output of the detection means. In view of the above, the present invention provides a noise suppression circuit that has a simple configuration and that ensures muting.

The present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a noise suppression circuit embodying the present invention.

1 is a transmitter of a remote control device.

Reference numeral 2 denotes a receiver of the remote control device, and the receiver includes a microphone 3 that converts a remote control signal such as an ultrasonic wave transmitted from the transmitter into an electrical signal, and a remote control signal received by the microphone. An amplifier 4 for amplifying a control signal, a signal selector 5, 5', 5'' for selecting and extracting only a specific control signal from a large number of remote control signals, and a signal selector 5, 5', 5'' for selecting and extracting only a specific control signal from a large number of remote control signals, and a signal selector 5, 5', 5'' that is controlled by the output of the selector. drive circuits 6 and 6'.

Reference numeral 7 denotes an envelope detection circuit, and 8 smooths and shapes the output of the detection circuit, so that its rise coincides with the control signal.
A waveform shaping circuit outputs a pulse signal with an extended pulse width so that its falling edge is slightly delayed from the end point of the control signal, 9 is a television receiver, 10 is an audio intermediate frequency circuit, an audio low frequency circuit, etc. An audio signal circuit, 11 a video signal circuit such as a video intermediate frequency circuit or a video amplification circuit, and 12 a tuner.

Note that the receiver 2 of the remote control device is built into the television receiver 9.

Further, the remote control device shown in FIG. 1 uses continuous signals such as waveforms A and B during the transmission period t as the remote control signal. FIG. 2 shows a concrete circuit diagram of the block diagram shown in FIG. 1, and the same parts as in FIG. 1 are denoted by the same reference numerals.

In FIG. 2, Tr, Tr2 are transistor amplifiers,
5 and 5' are capacitors C, , C2 and inductances L, , L2, respectively, and have a resonance frequency f. , f2 are resonant circuits, Tr3 and Tr4 are amplifying transistors, 6 is a drive circuit for power ON/OFF operation and volume adjustment operation, and relay switch 13,
Steps for power ON/OFF operation and volume adjustment operation
It is composed of a relay 14. Reference numeral 6' denotes a drive circuit for channel selection operation, which is composed of a relay switch 15 and a channel selection drive motor 16.

Next, its operation will be explained. Now, when a remote control signal for ultrasonic channel selection (continuous wave of frequency f2: 42.0Hz) is transmitted from the transmitter 1, it is converted into an electrical signal by the microphone 3, amplified by the amplifier 4, and then the signal is sorted. 5', amplified by transistor Tr4, and a current flows through the coil of relay switch 15. When no current flows through the coil, normal off switch S2, which is in the OFF state, is closed, and channel selection is performed. The drive motor 16 is driven to perform channel selection on the television receiver. In this case, since it is necessary to sequentially perform the tuning operation from a certain channel to another desired channel, the transmitter 1 transmits a continuous waveform like waveform A during the required selection time t. A remote control signal is being sent.

This continuous remote control signal is derived from the collector of the transistor Tr4 and applied to the envelope detection circuit 7 to obtain a pulse with a waveform such as C.
and field effect transistor Tr6 and smoothing circuit 24
The pulse waveform is shaped into a pulse waveform D by the waveform shaping circuit 8 made up of the above, and applied to the gate circuit 17 made up of the transistor Tr7 and the diode D2, and the gate circuit is made conductive during the period of transmitting the remote control signal. The audio signal circuit 10 or the video signal circuit 11, for example, the audio signal or video signal is bypassed to the ground point on the input side of the audio intermediate frequency or video amplification transistor Tr8, and the transmission of the audio signal to the subsequent stage is cut off. . In this way, the generation of noise caused by the channel selection operation by the remote control device is prevented. In this case, in connection with the remote control signal, an AC signal with a duration approximately equal to the duration of the remote control signal also appears at point P of the drive circuit 6', so this voltage should be used for noise suppression (as indicated by the broken line). The wires may be connected as shown in the figure.

In that case, it is necessary to break the wire at point Q. Figures 1 and 2
It will be easily understood that the periods t of the remote control signals A and B in the figure do not have to be constant.

The point is that the drive circuit 6' continues the channel switching operation during each period t during which the control signal exists, and completes channel switching as the control signal ends.On the other hand, during the period t during which the control signal exists. Even if the mute pulse is not constant but arbitrary, the fall of the mute pulse is always delayed by a certain amount of time than the end of the control signal, and the desired mute is performed. FIG. 3 shows an example in which the present invention is applied to a television receiver equipped with a remote control device for compatibility; a variable capacitance diode is used in the tuner selection device of the television receiver, and a so-called electronic tuning type This is a channel selection device.

The remote control device is composed of a digital circuit, and the time required for tuning operations is extremely short.At first glance, it appears to be a direct switching tuning system, but in a strict sense, it is a sequential tuning system. It is a method. The correspondence switching remote control device shown in FIG. 3 will be explained.

A compatible switching remote control device is a device in which the same number of remote control signals of the transmitter of the remote control device is provided corresponding to the number of selectable channels of the channel selection device of the television receiver, and is, for example, a controlled device. To select channel A on the channel selection device, send the a control signal from the remote control device,
Similarly, to select the B channel, the b control signal is sent, and the number of remote control signals and the number of channels that can be selected (or the number of operations of the controlled device controlled by the remote control signal) are determined. This is a device that has a one-to-one correspondence between the two. To explain this compatible control device in more detail, if we assume that a TV receiver's channel selection device can select 10 channels, the transmitter of the remote control device will generate one unique remote control signal. In order to do this, the transmitter is provided with a lq-fixed tuning switch, and by pressing the first tuning switch, one pulse modulated pulse train remote control signal is transmitted from the transmitter, and the second tuning switch is pressed. By pressing , the transmitter transmits two pulse-modulated pulse train remote control signals in the same manner as described above, while the receiver of the remote control device provided in the receiver receives the aforementioned control signals, The remote control device selects the receiver channel corresponding to the remote control signal.

In a television receiver equipped with such a corresponding remote control device for sliding doors, the receiver of the remote control device receives a remote control signal transmitted from the transmitter, and the first First, a reference channel is preset by a pulse, and the fog station is sequentially switched from the reference channel one channel at a time for each pulse, and a desired channel is received.

Next, the operation of the circuit shown in FIG. 3 will be explained. In the figure, parts similar to those in FIG. 1 are designated by the same reference numerals. Since the receiver 2 of the remote control device shown in FIG. 3 is almost the same as that described in Tokugan Sho 46-91251, which was invented by the same inventor, a brief explanation will be provided. For example, if the third channel selection switch of transmitter 1 of the remote control device is pressed and the transmitter transmits an ultrasonic remote control signal containing three pulses as shown in FIG. The signal is microphone 3
The signal is converted into an electrical signal, amplified by the amplifier 4, sorted by the signal selector 5', applied to the detector 18, shaped into a pulse waveform as shown in FIG.
9 is applied.

When a pulse train remote control signal as shown in FIG. 4 is applied to the pulse discriminator 19, only the first pulse x appears at the reset signal output terminal n as shown in FIG. The first pulse × does not appear at the output terminal m, and the second and third pulses
Only pulses Y and Z appear.

These reset signals and shift signals are applied to the channel selection circuit 201, the reset signal resets the channel selection circuit to a reference channel, for example, the first channel, and the shift signal is counted to perform a desired channel selection operation. In this case, since the above-mentioned station switching operation is completed instantaneously, it is as if the desired third channel is selected at the same time as pressing the third channel selection switch, and the desired third channel is selected at the same time as when the third channel selection switch is pressed. A desired channel can be selected in accordance with the selected channel selection switch, and a so-called compatible switching remote control system becomes possible. Now, in such a compatible remote control device for sliding doors, when selecting the 10th channel, for example, the tuning device of the tuner 12 from the second channel selection circuit first selects the first channel for 20 milliseconds (msec). 20 (ms) on the second channel
ec), similarly, the 3rd, 4th, 5th, 6th, 7th, 8th, and 9th channels are also stopped for 20 (msec), for a total of 180 (msec).
), the station stops at an undesired channel, and during that time, noise from an empty channel or noise from a broadcast signal from a broadcast channel is received.

In order to suppress such noise, in FIG. 3, the remote control signal is extracted from the amplifier 5', detected by the detection circuit 7 to form a waveform as shown in FIG. The output signal is connected to a field effect transistor Tr.
9, Tr. The gate pulse is applied to the impedance conversion circuit 22 consisting of the following, to create a gate pulse as shown in the tree in FIG. to suppress noise in audio or video. FIG. 5 is a specific circuit connection diagram of the main part of FIG. 3, and the terminal 23 is a terminal provided so that it can be applied to the sequential switching channel selection method shown in FIGS. 1 and 2. Yes, the output of a waveform shaping circuit that uses a regular switching channel selection method is applied.

As described above, although the present invention uses a remote control signal for channel selection, it applies a mute pulse separately from the channel selection system, and the rear end of the mute pulse [output of the waveform shaping circuit 8] Since it is not controlled in any way by the channel selection system, the overall configuration is simple.

Since the trailing end of the mute pulse falls after channel switching is completed, audio and video are reliably muted.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a noise suppression circuit of a television receiver equipped with a remote control device of the present invention, FIG. 2 is a specific circuit connection diagram thereof, and FIG. 3 is a television receiver equipped with a pulse train remote control device. FIG. 4 is a diagram for explaining FIG. 3, and FIG. 5 is a specific circuit diagram of the main part of FIG. 3. 1... Transmitter of remote control device, 2...
Receiver of remote control device, 4... Remote control signal amplifier, 6, 6'... Drive circuit, 8...
Waveform shaping circuit, 9... Television receiver, 10.
... Audio signal circuit, 11 ... Video signal circuit, 21, 24 ... Smoothing circuit. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. In a television receiver equipped with a remote control device that can perform channel selection operations, the remote control device performs channel selection operations only while a control signal is being received, and when this control signal ends, it switches channels. A driving circuit is provided which is directly controlled by the control signal so that the control signal is completed, and a part of the control signal is envelope-detected and passed through a waveform shaping circuit including a smoothing circuit, so that the rising edge of the control signal is controlled directly by the control signal. , but the pulse width is extended so that the falling edge is slightly delayed from the end point of the control signal, and this pulse signal is used as a gate pulse to control the sound of the television receiver over its duration. A noise suppression circuit for a television receiver equipped with a remote control device, characterized in that it disables a signal circuit or a video signal circuit.