JPS6339150B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a circuit configuration for switching the operation of an AFC circuit in a case where a channel selection circuit with an AFC circuit is provided for a television receiver and a recording device, respectively. AFC during recording
It is an object of the present invention to provide a device whose state is not accidentally switched.

Recently, recording devices such as video tape recorders are increasingly being used in combination with television receivers. In this case, it is often desirable to have different channels for viewing on the television receiver and recording channels on the recording device, so separate channel selection circuits are provided for the television receiver and for the recording device. is common. However, when providing two sets of channel selection circuits, conventionally each channel selection circuit had a separate switch for switching the operation of each AFC circuit, so the switching operation was difficult. It is complicated and troublesome, and it is easy to make mistakes in operation, and there are problems in that the recording state on the recording device may be different from the desired AFC state.

Therefore, the present invention solves such conventional drawbacks, and enables the operations of the AFC circuits of the respective channel selection circuits for television receivers and recording devices to be switched in conjunction with one set of switches, and furthermore, When recording with a recording device, even if the AFC switch is changed during television reception, the AFC switch is set in advance according to the reception status of the recording channel.
It is an object of the present invention to provide a device capable of recording in a desired AFC state without changing the AFC state.

EMBODIMENT OF THE INVENTION Hereinafter, the present invention will be described in detail with reference to the drawings showing one embodiment thereof.

In the figure, 1 is a channel selection circuit for a television receiver, 2 is a channel selection circuit for a recording device, and includes tuners 3 and 4, and AFC circuits 5 and 6 that apply AFC voltage for AFC control to them. , and AFC switching circuits 7 and 8 for switching whether to operate or stop the AFC circuits 5 and 6. In addition,
9 and 10 are default pulse generation circuits that generate an AFC default pulse for stopping the AFC operation for a certain period of time of about 0.3 seconds each time the channels are switched in the respective channel selection circuits 1 and 2; 11; Reference numeral 12 denotes a waveform shaping circuit which makes the pulse widths of the daily pulses uniform and supplies them to the AFC switching circuits 7 and 8 via diodes 13 and 14.

On the other hand, 15 is the AFC circuit 5, 6 by manual operation.
A switch 16 is used to switch the operation of the AFC circuits 5 and 6 in accordance with the opening and closing of the door of the storage chamber in which the variable resistor for presetting the tuning voltage of the tuning circuits 1 and 2 is housed. It is a switch,
Both switches 15 and 16 are configured to stop the AFC operation when closed.
Further, the switch 16 is configured to be closed when the door is opened to adjust the channel selection voltage.
These switches 15 and 16 are connected in parallel, and the output from one end is directly supplied as an AFC switching control voltage to the AFC switching circuit 7 of the channel selection circuit 1 for the television receiver, and is also applied to the state holding circuit 17. ing. This state holding circuit 17 is mainly composed of a latch circuit, etc., and its holding control terminal H
During the period when a low-level control voltage is applied to the input terminal I, the input to the input terminal I at the time of application is held, and even if the input changes thereafter, the held content is output as is, and the low-level control When no voltage is applied, the input to the input terminal I is passed through as is and output. This state holding circuit 1
The output of 7 is inverted by an inverter 18 and applied to the base of a switching transistor 19, and from the transistor 19 to the channel selection circuit 2 for the recording device.
An AFC switching control voltage is applied to the AFC switching circuit 8.

Furthermore, 20 is a recording control circuit in the recording apparatus, which generates a low-level state detection output when the recording apparatus is in a recording operation state. Also,
Reference numeral 21 denotes a recording timer circuit in the recording device, which is arbitrarily set to perform a recording operation at a preset predetermined time. A level condition detection output is generated. The recording standby state detection outputs from both circuits 20 and 21 are applied to the holding control terminal H of the state holding circuit 17 via diodes 22 and 23.

Next, the operation in such a configuration will be explained. First, it is assumed that the recording device is neither in a recording state nor in a recording standby state. At this time, since the input and output of the state holding circuit 17 are always the same, the switching transistor 19
It turns on and off in the same state as the on and off states of 5 and 16 parallel circuits. Therefore, at this time, if the switches 15 and 16 are both turned off, the switching transistor 19 will also be turned off, and the AFC operation stop control voltage will not be applied to either of the two channel selection circuits 1 and 2, and the AFC circuit will be turned off. 5 and 6 both work. Furthermore, when either the switch 15 or 16 is turned on, the switching transistor 19 is also turned on, and both the channel selection circuits 1 and 2 are turned on.
AFC operation stop control voltage is applied to the AFC circuit 5,
6, both stop operation. In this way,
At this time, the AFC operations of the two channel selection circuits 1 and 2 can be switched in conjunction with the switches 15 and 16.

Therefore, in this state, adjust the channel selection circuit 2 for the recording device, close the door and turn off the switch 16, and then record with the AFC circuit 6 operating.
It can be set by the switch 15 whether to stop the operation of the AFC circuit 6 and record the video.

Next, in the recording device, the recording control circuit 20 is operated to put it into a recording operation state, or the recording timer circuit 21 is operated to put it into a recording standby state. Then, a low level status detection output is output from either the circuit 20 or 21 and the status holding circuit 17 is output.
added to. Therefore, the state holding circuit 17 holds the AFC operation setting input from the switches 15 and 16 immediately before it, and thereafter outputs the held contents until the recording operation is completed.
Therefore, the switching transistor 19 is maintained in a preset on or off state by the output of the state holding circuit 17 until the end of recording. As a result, when the switches 15 and 16 are changed thereafter, only the operating state of the AFC circuit 5 of the channel selection circuit 1 for the television receiver is changed.
The AFC circuit 6 of the channel selection circuit 2 for the recording device is maintained in a preset operating state regardless of the switching of the switches 15 and 16. Therefore, in other words, even in the recording state or the recording command state, the AFC operation state of the recording device is not affected.
Switches 15 and 16 turn on the television receiver.
The AFC operating state can be changed freely.

As described above, according to the present invention, the AFC operations of the channel selection circuits for the television receiver and the recording device can be switched in conjunction with each other using a single AFC changeover switch, thereby reducing the number of switches. The circuit can be simplified and the operability can be greatly improved. In addition, when a recording device is in a recording state or a recording standby state, the AFC operation of the channel selection device for that recording device is maintained at the previous setting state, so that the recording device can be set in a preset state. It is possible to record correctly as is, and moreover, the AFC operation of the television receiver can be freely switched during recording. Also, above
By connecting in parallel to the AFC selector switch a second switch that opens and closes in conjunction with the opening and closing of the door of the storage chamber in which the variable resistor for presetting the tuning voltage of the tuning circuit is stored, the state holding circuit and switching The device can be used as is to achieve the intended purpose.

[Brief explanation of the drawing]

The figure is a circuit diagram of an AFC device in an embodiment of the present invention. 1... Tuning circuit for television receiver, 2...
...Tune selection circuit for recording device, 3, 4...Tuner,
5, 6...AFC circuit, 7, 8...AFC switching circuit,
15, 16...Switch, 17...State holding circuit, 18...Inverter, 19...Switching transistor, 20...Recording control circuit, 21...
Recording timer circuit, 22, 23...diode.

Claims (1)

[Claims] 1 A first AFC circuit provided in the channel selection circuit for the television receiver, a second AFC circuit provided in the channel selection circuit for the recording device, and the first and second AFC circuits provided in the channel selection circuit for the recording device.
first and second AFC switching circuits for switching between operating and stopping the AFC circuits; a first switch for switching the operation of the first and second AFC circuits by manual operation; The first variable resistor for presetting the tuning voltage of the tuning circuit opens and closes in conjunction with the opening and closing of the door of the storage chamber in which the variable resistor for presetting the tuning voltage of the tuning circuit is housed.
A second switch is connected in parallel to the second switch, and during the period when a control voltage of a predetermined level is applied to the control terminal, the input to the input terminal is maintained at the time when the control voltage is applied, and the input changes thereafter. a state holding circuit that outputs the held content as is even when the control voltage is applied, and that outputs the input to the input terminal by passing it as is when the control voltage at the predetermined level is not applied;
A recording control circuit and a recording timer circuit that generate a detection output at the predetermined level and supply it to the control terminal when recording or in a recording standby state, and a power supply terminal and an input terminal of the second AFC switching circuit. a switching element inserted between the switches and controlled on/off by the output of the state holding circuit, one end of the parallel circuit of the first and second switches is connected to the power supply terminal, and the other end is connected to the first switch. An AFC device, characterized in that it is connected to an input terminal of an AFC switching circuit and an input terminal of the state holding circuit.