JPH0237141B2 - SHINGOKIRIKAESOCHI - Google Patents

Description

[Detailed description of the invention]

Industrial Application Field The present invention is suitable for receiving satellite (SHF) broadcasting.
This invention relates to a signal switching device in a television receiver with a built-in SHF tuner. Conventional Structure and Problems Satellite broadcasting has now been put into practical use, and television receivers capable of receiving it have been proposed. Currently, a so-called SHF tuner for receiving satellite broadcasts (hereinafter referred to as SHF broadcasts) is installed separately from the television receiver.
The SHF tuner demodulates the received SHF signal into a baseband composite video signal and audio signal, and allows channel selection. and is input to the audio input terminal, and the video and audio are projected on a cathode ray tube screen and emitted from a speaker via a video processing circuit and an audio processing circuit. Incidentally, a so-called SHF tuner built-in television receiver has been proposed in which the above-mentioned SHF tuner is integrated into the television receiver so that operations such as signal switching can be performed easily. First, the configuration of such a television receiver with a built-in SHF tuner will be explained. In Figure 1, 1 is a VHF/UHF tuner, 2 is a circuit that detects and processes the output of tuner 1, and 3 is a circuit that detects and processes the output of tuner 1.
SHF tuner 4 receives the composite video signal and audio signal from circuit 2 above.
A switching circuit that switches the composite video signal and audio signal from the SHF tuner 3, 5 a control circuit that controls this switching circuit 4, 6 and 7 each an external video and audio input terminal, 8 the output of the switching circuit 4 and the external A switching circuit that switches and outputs the video and audio signals applied to the video and audio input terminals 6 and 7, 9 a control circuit that controls this switching circuit 8, 10 a 21-pin terminal for connecting a character multiplexing adapter 11, 1
2 is a switching circuit that switches and outputs the composite video signal supplied from this 21-pin terminal 10 and the output of switching circuit 8, 13 is a control circuit that controls this switching circuit 12, 14 is a video processing circuit, and 15 is a chroma output circuit, 16 is a deflection circuit, 17 is a color cathode ray tube, 1
8 is an audio processing circuit, 19 is an audio output circuit, and 20 is a speaker. Therefore, in the above configuration, each control circuit 5,
At 9 and 13, SHF tuner 3 is connected to switching circuit 4.
Each switching circuit 4,
By controlling the channels 8 and 12, it becomes possible to view the program of the desired channel of the SHF broadcast received and selected by the SHF tuner 3. Here, in the SHF receiving system equipped with the SHF tuner separately from the receiver as described above,
In order to receive and view SHF broadcasts, the television receiver must first be set to video mode and the SHF tuner must be operated to select a channel, which is cumbersome to operate. Therefore, in a television receiver equipped with the above-mentioned SHF tuner, each channel selection switch (tuning button) for VHF broadcasting, UHF broadcasting, and SHF broadcasting is placed on the front of the television receiver body. VHF or UHF by simply pressing the channel selection button
It is desirable to be able to select a broadcasting channel or SHF broadcasting channel, and to operate so that the broadcast waves of the selected channel are supplied to the video/audio processing circuit. On the other hand, in Japan, there are areas where it is not possible to receive VHF/UHF broadcasts, and where only SHF broadcasts can be received;
Priority is given to broadcasting, that is, when the power is turned on,
There are some areas where people want to receive and watch SHF broadcasts. Therefore, it is desired to develop a device that satisfies these demands. Purpose of the Invention In view of the above-mentioned requirements, the present invention enables settings to be made so that either VHF/UHF broadcasting or SHF broadcasting is received with priority, and by operating the channel selection button, the desired broadcasting can be selected. It is an object of the present invention to provide a signal switching device capable of selecting a channel and selectively supplying the signal to a processing circuit. Composition of the Invention A channel selection control device according to the present invention includes a priority selection switch that can be set to preferentially receive either VHF/UHF broadcasting or SHF broadcasting;
It is equipped with a signal switching circuit that allows you to select a desired channel by operating a selection button and selectively supply that signal to a processing circuit.
When the power is turned on, the priority selection switch above selects the
It is now possible to watch SHF broadcasts, and by operating the channel selection button, the switching circuit can be controlled to supply the television signal of that channel (broadcast wave) to the signal processing circuit, making it easy to operate. This is extremely convenient in practice. DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. FIG. 2 shows the configuration of main parts of the control circuit 5 shown in FIG. 1. In the figure, 21 is a control circuit composed of two J-K flip-flops having reset terminals R ₁ and R ₂ , and 22 is a priority selection switch that determines the state of the switching circuit 4 when the power is turned on. The terminal a is connected to the output Q ₁ (9 pin terminal) of the control circuit 21, the second fixed terminal b is connected to the output ₂ (13 pin terminal), and the movable terminal is connected to the switching circuit 4. are doing. 23 and 24 are NAND gates, and one input of NAND gate 23 is SHF.
The SHF daily pulse generated when selecting a broadcast station is supplied, and the other input is in video mode (when external video signals applied to terminals 6 and 7 are selected). A signal is added that becomes a low level "L" and becomes a high level "H" in other modes. In addition, one input of the NAND gate 24 is supplied with the VHF/UHF daytime pulse generated when selecting a VHF/UHF broadcast, and the other input is supplied with a low pulse only in the above video mode. Level “L”
It supplies the signal. The output of the NAND gate 23 is connected to the control input _C1 , and the output of the NAND gate 24 is connected to the control input _C2 .
Further, reset terminals R ₁ and R ₂ of the control circuit 21 are connected to a 12V terminal via resistors 25 and 26, respectively, and to a power supply reset circuit (not shown) via diodes 27 and 28, and are further connected to a reset terminal R. ₁ to control input C ₂ via diode 29,
The reset terminals R ₂ are each connected via a diode 30 to the control input C ₁ . Next, the operation of the above configuration will be explained.
First, assume that the priority selection switch 22 is connected to the fixed terminal a as shown in the figure. Here, when the power is turned on, the power supply reset circuit momentarily goes to low level and then goes to high level, but at this low level, the reset input terminals R ₁ and R ₂ go to low level and the control circuit 21 is reset, and the output _Q1 ,
_Q2 changes to low level, and outputs ₁ and ₂ change to high level. Therefore, since the priority selection switch 22 is in the above state, its output becomes a low level. Here, the switching circuit 4 is configured to selectively output a television signal of VHF/UHF broadcasting when the output of the control circuit 5 is at a low level, and to selectively output a television signal of SHF broadcasting when the output is at a high level. At this time, the switching circuit 4 is
VHF/UHF broadcast television signals are supplied to the switching circuit 8. Therefore, at this time, VHF/UHF broadcast programs will be displayed first with priority.
Then, when a VHF or UHF broadcast channel selection operation is performed, a VHF/UHF day-to-day pulse is generated, both inputs of the NAND gate 24 become high level, the output becomes low level, and the control input
As C ₂ becomes low level, diode 29
As a result, one reset terminal _R1 is reset, and the output state is that the output _Q1 remains at a low level, and the output ₂ is inverted and becomes a low level. Therefore, the output state of the priority selection switch 22 remains unchanged.
The switching circuit 4 continuously outputs the television signal of VHF/UHF broadcast. If you tune in to a VHF or UHF broadcasting channel and then tune in to an SHF broadcast,
Both inputs of the NAND gate 23 are at high level, so its output is at low level, and the control input C ₁
goes low level and the reset terminal _R2 is reset by the diode 30, and the output ₂
maintains a high level, but the output _Q1 is inverted and becomes a high level. Therefore, the switching circuit 4 is switched to selectively output the SHF broadcast television signal. On the other hand, if the priority selection switch 22 is set in advance to the fixed terminal b side, when the power is turned on, the control circuit 21 is reset and the output is
₂ becomes high level, so the switching circuit 4 becomes SHF.
Selectively outputs broadcast television signals. here
When you perform SHF broadcast tuning operation, NAND gate 2
Output 3 becomes low level, and output ₂ maintains high level, so switching circuit 4 continues to switch to SHF.
Outputs broadcast signals. While receiving SHF broadcasts,
When a UHF broadcast is selected, the output of the NAND gate 24 becomes low level, so the output ₂ is inverted and becomes low level, and the switching circuit 4 outputs a VHF or UHF broadcast television signal instead of the SHF broadcast. do. The following table summarizes the level states of output Q ₁ (pin 9) and output Q ₂ (pin 13) in each state.

[Table] According to this device, when the power is turned on using the priority selection switch 22, it is possible to determine which broadcast wave television signal should be given priority and supplied to the signal processing circuit. For example, only SHF broadcasts can be received. Even in areas where this is not possible, if this switch 22 is set to the fixed terminal B side in advance, the SHF broadcasting channel can be displayed simply by operating the power switch. When a channel is selected, the switching circuit 4 is automatically switched to select the broadcast wave to which the channel belongs based on the daily pulse generated by the channel selection operation. It can be supplied to a signal processing circuit, and it is possible to switch television signals simply by performing a channel selection operation, making the operation easy and extremely convenient in practice. Note that in FIG. 2, capacitors 31 and 32 are capacitors for preventing malfunction. Effects of the Invention As described above, according to the present invention, by controlling the switching circuit for television signals of VHF/UHF broadcasting and SHF broadcasting with a priority selection switch, the television signal that is supplied to the signal processing circuit when the power is turned on is You can select the signal in advance, for example, if you flip this switch to the SHF broadcast side,
Just by turning on the power, you can select the SHF broadcast television signal and supply it to the subsequent processing circuit.For example, even in areas where only SHF can be received, it is possible to watch the broadcast with a simple operation. Furthermore, from then on, the switching circuit can be automatically switched based on the signal generated in response to the channel selection operation, and the signal switching can also be performed by the channel selection operation, which is extremely convenient in practice.

[Brief explanation of drawings]

FIG. 1 shows the signal switching device of the present invention applied.
FIG. 2 is a block diagram of a television receiver with a built-in SHF tuner. FIG. 2 is a circuit diagram of a signal switching device according to an embodiment of the present invention. 1...VHF/UHF tuner, 3...SHF tuner, 4...VHF/UHF/SHF switching circuit, 21
...Control circuit, 22...Priority selection switch, 2
3, 24...NAND gate, 27, 28, 29,
30...Diode.

Claims (1)

[Claims] 1 VHF/UHF broadcast television signals and SHF
A broadcast television signal is input, and when the switching control signal is at the first potential, one of the television signals is input, and when the switching control signal is at a second potential different from the first potential, the other one is input. A switching circuit outputs television signals, a first fixed terminal is connected to a first terminal that shows a first potential when the power is turned on, and a second fixed terminal is connected to a second terminal that shows a second potential when the power is turned on. a priority selection switch having fixed terminals connected to each other and a movable terminal serving as an output terminal for the switching control signal;
The first signal generated when selecting a VHF/UHF broadcasting channel and the second signal generated when selecting an SHF broadcasting channel are input, and when the first signal is input, control means for causing both the first and second terminals to exhibit a first potential, and for causing both the first and second terminals to exhibit the second potential when the second signal is input; Signal switching device.