JPH0713325Y2 - Video signal switching device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a video signal switching device, and more particularly to a color television receiver (hereinafter abbreviated as color television) capable of connecting video signals from the front and rear surfaces. The present invention relates to an improvement in a video signal switching device suitable for video equipment such as a video tape recorder (hereinafter abbreviated as VTR).

[Problems to be solved by conventional techniques and devices]

Conventionally, in a video device capable of connecting a video signal from the front surface and the rear surface, if an image signal is connected to an input terminal provided on the front surface with respect to an input terminal provided on the rear surface, only the front surface can be input. There is a configuration in which when a video signal is connected to both rear surfaces, the video signal from the rear surface is output on the front surface, which functions as a so-called through terminal.

With the spread of portable small video cameras in recent years,
It has become necessary to improve the playback operability of the video camera by allowing the video camera to be input from the front of the video device.

On the other hand, as a video recording system, the S / VHS system, which requires higher image quality than the VHS system, is becoming widespread, and video equipment has both VHS and S / VHS system input terminals, and the S / VHS system S ・ V when video signal is connected
A video signal switching device that preferentially selects an input terminal for an HS signal is desired.

However, from the front and back of video equipment
Configured so that VHS and S / VHS video signals can be input,
Priority is given to the input terminals on the front, and S / VH
A video signal switching device that gives top priority to the S system video signal requires special measures and is required to be provided.

The present invention has been made under such a circumstance, and it is possible to give priority to the input terminal on the front side rather than the rear side of the image device and give priority to a specific input terminal on the front side. Video signal switching device.

[Means for Solving the Problems]

In order to solve such a problem, the first structure according to the present invention is the first and second structures arranged on the front side of the video equipment.
The front input terminal, the first and second rear input terminals arranged on the rear side of the video equipment, and the first and second changeover switch circuits.

The first front input terminal is connected to the first video signal and outputs a control signal when the first video signal is connected. The second front input terminal is connected to the second video signal. , The first rear input terminal is connected to the third video signal, and the second rear input terminal is connected to the fourth video signal.

Further, the first changeover switch circuit switches and outputs the first video signal and the third video signal and selects the first video signal by the control signal, and the second changeover switch circuit The video signal from the first changeover switch circuit and the fourth video signal are switched and output, and the first video signal is selected by the control signal.

The video signal from the first changeover switch circuit is connected to the second rear surface input terminal, and the second rear surface input terminal is connected to the fourth rear surface input terminal.
Is formed so as to preferentially select the fourth video signal by connecting the second video signal to the second front input terminal to which the second changeover switch circuit is connected, and the second front input terminal is connected to the second front input terminal. The connection of the two video signals is configured to preferentially select the second video signal.

Further, the second structure according to the present invention is the first and second front input terminals arranged on the front side of the video equipment and the first and second rear input terminals arranged on the rear side of the video equipment. And a first to a third switch circuit.

That is, the first front input terminal is connected to the first video signal, and when the first video signal is connected, the first
The second front input terminal is connected to the second video signal and outputs the second control signal when the second video signal is connected.

The first rear input terminal is connected to the third video signal, the second rear input terminal is connected to the fourth video signal, and the third control is performed when the fourth video signal is connected. It outputs a signal.

Further, the first changeover switch circuit switches and outputs the first and third video signals and preferentially outputs the first video signal according to the first control signal. The circuit switches and outputs the second and fourth video signals, and preferentially outputs the second video signal according to a second control signal.

The third switch circuit switches and outputs the video signals from the first and second changeover switch circuits, and when the second or third control signal is output, the video signal from the second changeover switch circuit. Is output by switching.

[Action]

In the first configuration of the present invention provided with such means, the second configuration
When the second video signal is connected to the front input terminal of, the second video signal is preferentially output, and the first video signal is connected to the first front input terminal in the state where the second video signal is not connected. Is connected, the first video signal is output via the first and second changeover switch circuits.

The second with the first and second video signals not connected
When the fourth video signal is connected to the rear surface input terminal, the fourth video signal is output via the second changeover switch circuit and the second changeover input terminal, and the first, second and fourth When the third video signal is connected to the first rear surface input terminal while the video signal is not connected, the third video signal is connected to the first changeover switch circuit, the second rear surface input terminal, and the second changeover switch. It is output via the circuit and the second front input terminal.

Further, in the second configuration of the present invention, when the second video signal is connected to the second front input terminal, the second video signal is preferentially output via the second and third changeover switch circuits. Then, when the first video signal is connected to the first front input terminal in the state where the second video signal is not connected, the first video signal is output via the first and third changeover switch circuits. It

The second with the first and second video signals not connected
When the fourth video signal is connected to the rear input terminal, the fourth video signal is preferentially output via the second and third changeover switch circuits, and the first, second and fourth video signals are output. When the third video signal is connected to the first rear surface input terminal with no signal being connected, the third video signal is output via the first and third changeover switch circuits.

〔Example〕

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

FIG. 1 is a block circuit diagram showing a first configuration of a video signal switching device according to the present invention.

In FIG. 1, a front video input terminal (first front video input terminal) 1 and a front S input terminal (second front video input terminal) 3 are video devices, such as a color television or a VT.
It is arranged on the front panel side of R and is connected with a video signal and an S video signal (first and second video signals), respectively.

The rear video input terminal (second rear video input terminal) 5 and the rear S input terminal (second rear video input terminal) 7 are arranged on the rear panel side, and the video signal and the S video signal (third and third video signals) are arranged. 4 video signals) are connected.

In the present invention, the connection of the video signal and the S video signal to each of the input terminals 1 to 7 is made by a connector, but the illustration and description thereof are omitted.

Further, although the video signal and the S video signal include an audio signal, the description and illustration thereof are omitted.

The front video input terminal 1 is connected to one fixed contact 9b of a changeover switch circuit (first changeover switch circuit) 9, and the other end of a resistor R ₁ having one end connected to a power source B is grounded. Have 11.

This switching circuit 11 has a resistance when the video signal is not connected.
The other end of R ₁ is set to the “L” level, and is set to the “H” level when the video signal is connected. It is designed to output to 29.

The changeover switch circuit 9 has movable contacts according to its control signal.
9a selects the fixed contact 9b, the rear video input terminal 5 is connected to the other fixed contact 9c, and the movable contact
9a is connected to the fixed contact 13b of the changeover switch circuit 13.

The other fixed contacts 13c and 13d of the changeover switch circuit 13 are respectively connected to the rear video input terminals 15 and 17, and the movable contact 13a is connected to the fixed contact 19c of the changeover switch circuit 19.

The remaining fixed contacts 19b and 19d of the changeover switch circuit 19 are connected to, for example, a tuner circuit (not shown) of a color television and a personal computer signal input terminal 21, and the movable contact 19a has a comb filter 23 and a video signal output terminal 25. It is connected to the.

In these changeover switch circuits 13 and 19, the movable contacts 13a and 19a are switched by a control signal from a control circuit (not shown), but normally the fixed contacts 13b and 19c are selected.

The comb filter 23 includes a video signal from the front video input terminal 1 and the rear video input terminal 5 and a VI from the tuner circuit.
The Y signal and the C signal are separated from the F signal and output. The Y signal is output to the fixed contact 27c of the changeover switch circuit (second changeover switch circuit) 27, and the C signal is changed to the changeover switch circuit (second changeover circuit). The switch circuit) 29 is connected to a fixed contact 29c.

The Y signal and C signal line from the rear S input terminal 7 are connected to the other fixed contacts 27b and 29b of the changeover switch circuits 27 and 29, and the rear S input terminal 7 is connected to the Y signal from the comb filter 23. A switch function is formed to connect the signal and the C signal to the Y signal and the C signal line, and to disconnect the Y signal and the C signal when the S video signal is connected.

The Y signal and the C signal from the comb filter 23 are connected to the fixed contacts 31c and 33c of the changeover switch circuits 31 and 33, respectively.

The movable contacts 27a and 29a of the changeover switch circuits 27 and 29 are connected to the Y signal and C signal lines from the front S input terminal 3.

The front S input terminal 3 has a switch function of disconnecting the Y signal and the C signal from the changeover switch circuits 27 and 29 when the S video signal is connected. Other fixed contacts of 31,33 31b, 33b
It is connected to the.

The movable contacts 31a and 33a of the changeover switch circuits 31 and 33 are connected to the rear video input terminals by a control signal from a control circuit (not shown).
The fixed contacts 31c and 33c are selected when video signals are input from the signal input terminals 15 and 17 and the personal computer signal input terminals, and Y and C signals are selected and output, respectively.

Reference numeral 34 in FIG. 1 is a cable for connecting the front video input terminal 1 and the front S input terminal 3 arranged on the front panel side to the changeover switch circuits 9, 13, 19, 27, 29, 31, 33. .

Next, the operation of the first configuration of the present invention thus constructed will be described.

First, a case where an S video signal is connected to the front S input terminal 3 will be described.

In this case, the Y signal and the C signal from the changeover switch circuits 27 and 29 at the front S input terminal 3 are the Y signal and the C signal.
Not connected to the signal line, the changeover switch circuit 31,3
Since the three fixed contacts 31b and 33b are selected, the S video signal applied to the front S input terminal 3 is transferred to the changeover switch circuit 31,3.
It is output as is via 3.

Therefore, the video signal and S are input to the other input terminals 1, 5 and 7, respectively.
Even if the video signal is connected, the S video signal connected to the front S input terminal 3 is unconditionally output.

Next, a case where a video signal is connected to the front video input terminal 1 while the S video signal is not connected to the front S input terminal 3 will be described.

In this state, even if a video signal is connected to the front video input terminal 1, the other end of the resistor R ₁ remains at “H” level, and the fixed contacts 9b, 27b, 29b of the changeover switch circuits 9, 27, 29 are connected. Is selected, the video signal changes to the changeover switch circuit 9,
The signals are output via 13, 19, comb filter 23, changeover switch circuits 27, 29, front S input terminal 3 and changeover switch circuits 31, 33.

In this case, even if the video signal and the S video signal are connected to the rear video input terminal 5 and the rear S input terminal 7, the video signal applied to the front video input terminal 1 is preferentially output.

Further, a case where an S video signal is connected to the rear S input terminal 7 while no signal is connected to the front S input terminal 3 and the front video input terminal 1 will be described.

In this state, since the other end of the resistor R ₁ is grounded by the changeover circuit 11 and becomes the “L” level, the changeover switch circuits 9, 2
As for 7,29, movable contacts 9a, 27a, 29a are switched to fixed contacts 9c, 27b, 29b, respectively.

At the rear S input terminal 7, Y from the comb filter 23
Signal and C signal are separated from the Y signal and C signal lines, and the S video signal from the rear S input terminal 7 is changed over to switch switch circuits 27, 29, front video input terminal 1, changeover switch circuit.
It is output via 31,33.

In this case, even if a video signal is connected to the rear video input terminal 5, the changeover switch circuits 27 and 29 and the rear S
By the switching operation of the input terminal 7, the S video signal from the rear S input terminal 7 is preferentially output.

Further, a case where the video signal is connected only to the rear video input terminal 5 and the signal is not connected to the other terminals will be described.

In this state, the changeover switch circuits 9, 13, 19 are similar to the state in which they are connected to the S video signal at the rear S input terminal 7,
The video signal applied to the rear video input terminal 5 is the changeover switch circuits 9, 13, 19, the comb filter 23, the rear S input terminal
7, the changeover switch circuits 27 and 29, the front S input terminal 3, and the changeover switch circuits 31 and 33.

As described above, in the first configuration according to the present invention, the signals are preferentially selected and output in the order of the front S input terminal 3, the front video input terminal 1, the rear S input terminal 7, and the rear video input terminal 5. The signal connected to the subsequent terminals is output only when the signal is not applied to the priority input terminal.

Therefore, the front S input terminal 3 and the front video input terminal 1 arranged on the front side of the color television are connected to the rear S input terminal 7
Also, it is possible to preferentially output to the rear video input terminal 5.

Moreover, by simply connecting a video signal or an S video signal to each of the input terminals 1 to 7, the signal is switched by the switch operation of each of the signal terminals 3 and 7, and the operation of the switching circuit 11 formed in the front video input terminal 1 is performed. Since each changeover switch circuit 9, 27, 29 is switched by the control signal based on the above, the circuit configuration is extremely simple and inexpensive.

FIG. 2 is a block circuit diagram showing a second configuration of the video signal switching device according to the present invention.

The structure of the front video input terminal 1, the changeover switch circuits 9, 13, 19 and the comb filter 23 is the same as that shown in FIG.

The comb filter 23 sends the Y signal to the fixed contact 35c of the changeover switch circuit (third changeover switch circuit) 35 and the C signal to the fixed contact 37 of the changeover switch circuit 37 (third changeover switch circuit).
output to c.

The Y signal and C signal lines extending from the front S input terminal (second front video input terminal) 39 are fixed contacts of the changeover switch circuits 35 and 37 via the switch circuits (second changeover switch circuits) 41 and 43, respectively. It is connected to 35b and 37b.

The front S input terminal 39 has a switch circuit 45 whose one end is connected to the power source B via the resistor R _{2 and} whose other end is grounded, and which is always short-circuited when the S video signal is connected.
Has the function of opening.

The connection point between the switch circuit 45 and the resistor R ₂ is connected to the inverter I ₁ and the OR circuit 57 described later, and also the switch circuit.
It is designed to control the opening and closing of 41 and 43.

That is, when the S video signal is connected and the switch circuit 45 is opened, the other end of the resistor R ₂ becomes “H” level to output the control signal.

The Y signal and C signal lines extending from the rear surface S input terminal (second rear surface video input terminal) 47 are switched through the switch circuits (second changeover switch circuits) 49, 51.
It is connected to the fixed contacts 35b and 37b of 37, and its switch circuits 49 and 51 are controlled to be opened and closed by the output from the inverter I _1, and the output of the inverter I ₁ is short-circuited at the “H” level,
The release control is performed at the "L" level.

That is, when the S video signal is connected to the front S input terminal 39, the Y signal and C from the front video input terminal 1 are input.
When an S video signal is connected to the rear S input terminal 47 on the signal line, the Y signal and C from the rear S input terminal 47 are output.
The signal line is connected to the changeover switch circuits 35 and 37.

The rear S input terminal 47 has a switch circuit 53 whose one end is connected to the power source B through the resistor R ₃ and whose other end is grounded.
Switch circuit that always short-circuits when a video signal is connected
It has a function of opening 53, and a control signal is generated by the opening operation of the switch circuit 53 by connecting the S video signal.

Control signal lines from the other end of the resistor R ₁ is connected to the inverter I _2, the inverter I ₂ is connected to one input terminal of 2-input AND circuit 55, the other input terminal resistor R ₃ and the switch circuit 53
Is connected to the connection point of.

The output end of the AND circuit 55 is connected to the other input end of the 2-input OR circuit 57, and the output end of the OR circuit 57 is the changeover switch circuit 3
It is designed to control 5,37.

When the S video signal is connected to the front and rear S input terminals 39 and 47, the output of the OR circuit 57 becomes "H" level, and when the video signal is connected to the front and rear video input terminals 1 and 5. When the output terminal of the OR circuit 57 is at "L" level and the control signal from the OR circuit 57 is at "L" level, the movable contacts 35a, 37a have fixed contacts 35c, 3a.
5c is selected, and in other cases, the movable contacts 35b and 37b are selected.

That is, the inverter I ₂ , the OR circuit 55 and the AND circuit 57 form a control circuit 59 for switching control of the changeover switch circuits 35 and 37 by the control signals from the changeover circuit 11, the front S input terminal 39 and the rear S input terminal 47. ing.

The other structure is substantially the same as that shown in FIG.

Next, the operation of the second structure having such a structure according to the present invention will be described.

First, when an S video signal is connected to the front S input terminal 39,
The switch circuit 45 is opened and the switch circuits 41 and 43 are short-circuited, while the switch circuits 49 and 51 are opened and the front side S
The S video signal applied to the input terminal 39 is the switch circuit 41, 4
5, output through the changeover switch circuits 35 and 37.

Therefore, even if signals are connected to the other input terminals 1, 5, 47, the S video signal connected to the front S input terminal 39 is unconditionally output.

Next, when the video signal is connected to the front video input terminal 1 in the state where the S video signal is not connected to the front S input terminal 3, the fixed contact 9b of the changeover switch circuit 9 is selected and the control signal from the OR circuit 57 is selected. Becomes "L" level and the fixed contacts 35c and 37c of the changeover switch circuits 35 and 37 are selected.

Therefore, the video signal added to the front video input terminal 1 is output via the changeover switch circuits 9, 13, 19, the comb filter 23, and the changeover switch circuits 35, 37, and the rear S input terminal 4
Even if the S video signal is connected to 7 and the video signal is connected to the rear video input terminal 5, the video signal applied to the front input terminal 1 is preferentially output.

Furthermore, front S input terminal 39 and front video input terminal 1
Signal is not applied to the rear S input terminal 47
When the S video signal is connected to the
Switch circuit 45 is short-circuited, the switch circuit 53 of the rear S input terminal 47 is opened, the control signal from the OR circuit 57 becomes "H" level, and the fixed contacts 35b, 37b of the changeover switch circuits 35, 37 are short-circuited. On the other hand, the switch circuits 41 and 43 are opened and the switch circuits 49 and 51 are short-circuited.

Therefore, the S video signal applied to the rear S input terminal 47 is output via the switch circuits 49, 51 and the changeover switch circuits 35, 37.

In this state, the S video signal from the rear S input terminal 47 is output prior to the video signal from the rear video input terminal 5.

Finally, when a video signal is connected to the rear video input terminal 5 in a state where no signal is connected to the rear video input terminal 5, the fixed contact 9b of the changeover switch circuit 9 is selected and the OR circuit 57 The control signal becomes "L" level and the fixed contacts 35c, 37c of the changeover switch circuits 35, 37 are selected.

Therefore, the video signal connected to the rear video input terminal 5 is output through the changeover switch circuits 9, 13, 19, the comb filter 23 and the changeover switch circuits 35, 37.

In the second configuration as well, similar to the first configuration, the front S input terminal 3 and the front video input terminal 1 on the front side of the color television have priority over the rear video input terminal 5 and the rear S input terminal 7. And the front S input terminal 3 is unconditionally selected with respect to the front video input terminal 1.

In addition, the switch operation of the front S input terminal 39 and the rear S input terminal 47 and the operation of the switching circuit 11 in the front video input terminal 1 can be achieved simply by connecting signals to the respective input terminals 3, 5, 39, 47. , 43,49,51 and the changeover switch circuits 9,35,37 are changed over.
The configuration is extremely simple.

In the above-mentioned configuration, the front video input terminal 1 and the front S input terminals 3 and 39 are front input terminals, and the rear video input terminal 5 and the rear S input terminals 7 and 47 are rear input terminals. The present invention is not limited to the video signal and the S video signal, but can be applied to the priority switching control of the video signal and the video signal having a specific relationship with the video signal.

[Effect of device]

As described above, according to the present invention, when the first to fourth video signals are connected, the second and first front input terminals and the second front input terminal are connected.
And the first rear-face input terminal is preferentially switched, and when any of the preferential first to fourth video signals is not connected, the above-mentioned priority is given to the input terminals to which the video signal is connected. Video signals to the input terminal on the front side are prioritized over the rear side of the image device, in which the video signals are selected and output in order, and there is no S / VHS video signal connected to a specific input terminal on the front side. It can be selectively output depending on the conditions.

Moreover, since the first front input terminal has the control signal output function and the second front input terminal and the second rear input terminal have the switch function, the configuration is not complicated and the cost is low.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing a first configuration of a video signal switching device according to the present invention, and FIG. 2 is a block circuit diagram showing a second configuration of the present invention. 1 …… First front video input terminal (front video input terminal) 3,39 …… Second front video input terminal (front S input terminal) 5 …… First rear video input terminal (rear video input terminal) 7,47 …… Second rear video input terminal (rear S input terminal) 9 …… First changeover switch circuit (changeover switch circuit) 13,19,31,33 …… Changeover switch circuit 11 …… Changeover circuit 15 , 17 …… Rear side video input terminal 21 …… Personal computer signal input terminal 23 …… Comb filter 25 …… Video signal output terminal 27, 29 …… Second changeover switch circuit (changeover switch circuit) 35, 37 …… 3 changeover switch circuit (changeover switch circuit) 41,43,49,51 ...... second changeover switch circuit (switch circuit) 45,53 ...... switch circuit 55 ...... AND circuit 57 ...... OR circuit 59 ...... control Circuit R _{1 to} R ₃ ...... Resistance I ₁ , I ₂ ...... Inverter

Claims (2)

[Scope of utility model registration request] 1. A first front input terminal, which is arranged on the front side of a video device and to which a first video signal is connected, and which outputs a control signal when the first video signal is connected, A second front input terminal arranged on the front side of the video equipment and connected to a second video signal; and a first rear input terminal arranged on the rear side of the video equipment and connected to a third video signal. A second rear surface input terminal arranged on the rear surface side of the video device and connected to a fourth video signal; switching between the first video signal and the third video signal and outputting the same; A first change-over switch circuit for selectively outputting a first video signal; a video signal from the first change-over switch circuit; and a fourth video signal. A second changeover switch circuit for selectively outputting the first video signal, wherein the video signal from the first changeover switch circuit is connected to the second rear surface input terminal, and the second rear surface input A terminal is formed to preferentially select the fourth video signal by connecting the fourth video signal, the second changeover switch circuit is connected to the second front input terminal, and the second front switch terminal is connected to the second front input terminal. 2. The video signal switching device according to claim 1, wherein the front input terminal is formed so as to preferentially select the second video signal by connecting the second video signal. 2. A first front input terminal which is arranged on the front side of a video device and to which a first video signal is connected, and which outputs a first control signal when the first video signal is connected. A second front input terminal that is arranged on the front side of the video device and is connected with a second video signal, and outputs a second control signal when the second video signal is connected; A first rear surface input terminal arranged on the rear surface side of the equipment and to which a third video signal is connected, and a fourth video signal arranged on the rear surface side of the video equipment and connected to this fourth video signal. A second rear surface input terminal that outputs a third control signal when is connected, and outputs the first and third video signals by switching and outputs the first video signal by the first control signal. Output selectively A first changeover switch circuit; and a second changeover switch circuit which selectively outputs the second and fourth video signals and selectively outputs the second video signal in response to the second control signal, When the video signals from the first and second changeover switch circuits are switched and output, and the second or third control signal is output and the first control signal is not output, the second changeover switch circuit is output. And a third switch circuit for switching and outputting the video signal of 1., and a video signal switching device.