JP3131903B2 - Connection switching device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Table of Contents] Overview Industrial application field Conventional technology (Fig. 3) Problems to be solved by the invention Means for solving the problem (Fig. 1) Action Embodiment (a) One Description of Embodiment (FIG. 2) (b) Description of Another Embodiment [Outline] Out of a plurality of external terminals, connection by cable connection connecting an external terminal connected to an external cable and an internal circuit. The purpose of the switching device is to automatically perform the switching operation by connecting a cable so as to save labor and eliminate the need to provide a changeover switch. A signal switching unit for switching the connection between an external terminal and an internal circuit, and a connection switching system for connecting an external cable to one external terminal and connecting the external terminal connected by the signal switching unit to the internal circuit. The external cable is provided with a control signal line, a control terminal connected to the control signal line is provided, and the external cable is connected to a corresponding external terminal and connected to the control terminal. The signal switching unit is switched to the connected external terminal according to the control signal of the control signal line.

[Industrial applications]

The present invention relates to a connection switching device that connects an internal terminal to an external terminal to which an external cable is connected, among a plurality of external terminals.

For external input or external output of the device, an external cable is generally used, connected to an external terminal of the device, and connected to an internal circuit.

In this external input / output, a plurality of external terminals are provided to input or output various kinds of signals and are connected to the same internal circuit.

In this case, a switching circuit is provided between the plurality of external terminals and the internal circuit according to the difference in signal type and input / output, and the external circuit and the internal circuit are connected by the switching circuit. .

 It is desired that this switching be simple.

[Conventional technology]

 FIG. 3 is an explanatory diagram of the prior art.

For example, in a video converter 1 used for video input to a computer or the like, a video deck, a video camera, or a laser image disk device is connected via a cable.
NTSC signals are converted to RGB signals.

Such video signals include a video signal in which a color signal C and a luminance signal Y are mixed (NTSC composite signal),
An S-video signal (Y /
C-separate signal), and an NTSC external terminal 2a and an S-video external terminal 2b are provided to convert both into RGB signals.

Switching circuits 3a and 3b are provided to convert both of them into RGB signals by one NTSC-RGB conversion circuit 4d.

To connect the NTSC signal cable to the external terminal 2a and convert the NTSC signal to RGB signal, as shown in FIG.
a, 3b, and switches the NTSC signal from the external terminal 2a to the switching circuit 3a.
Then, the signal is guided to the video amplifier 4a, and the synchronization signal SYNC is separated by the sync separation circuit 4b after amplification.

The amplified output of the video amplifier 4a is the comb filter 4c
The color signal C and the luminance signal Y are separated from the NTSC composite signal, input to the NTSC-RGB conversion circuit 4d via the switching circuit 3b, and are converted and output into RGB signals.

On the other hand, in order to connect the S-video signal cable to the external terminal 2b and convert the S-video signal into an RGB signal, the switching circuits 3a and 3b are switched to the opposite side from FIG.

As a result, the Y signal of the S-video signal is input from the switching circuit 3a to the video amplifier 4a, and the synchronization signal SYNC is separated by the amplified synchronization separation circuit 4b.

On the other hand, the Y signal from the switching circuit 3a and the C signal from the external terminal 2b are input from the switching circuit 3b to the NTSC-RGB conversion circuit 4d and are converted into RGB signals.

As described above, the switching circuit 3a needs to be provided to cut an input signal from an external terminal to which no cable is connected. Further, since the switching circuit 3b shares the sync separation circuit 4b, it is necessary to provide the switching circuit 3b for cutting the output of the comb filter 4c of the Y signal of the S-video signal.

Such switching of the switching circuits 3a and 3b has conventionally been performed manually by providing a manual switching switch.

[Problems to be solved by the invention]

However, in the prior art, there is a problem that it takes time to manually operate the changeover switch together with the connection of the cable, and furthermore, a space for providing the changeover switch is required, and there is also a problem that it is difficult to reduce the size of the device.

Accordingly, the present invention provides a connection switching device using a cable connection in which a switching operation is automatically performed by connecting a cable to save labor and eliminate the need to provide a changeover switch. Aim.

[Means for solving the problem]

 FIG. 1 is a diagram illustrating the principle of the present invention.

As shown in FIG. 1, the present invention provides a plurality of external terminals 2a, 2a connected to a conversion cable to which an external cable is connected.
b, in a connection switching device each having a plurality of external terminals 2a, 2b for receiving signals from different types of external cables, the conversion corresponding to the type of the external cable connected to the conversion cable A control terminal 2c connected to a control signal line provided on the cable, and a signal switching unit 3 for switching connection between the plurality of external terminals 2a and 2b and the internal circuit 4 are provided. To connect the control signal line to the control terminal 2c, and switch the signal switching unit 3 to the connected external terminal according to a control signal from the connected control signal line. .

[Action]

According to the present invention, a control signal line CS is provided on the external cables 5a and 5b in addition to a normal signal line, and a control terminal 2c is provided on the device. The control signal of CS is inputted, and the signal switching section 3 is switched to the external terminal side connected to the cable.

For this reason, the switching section 3 is automatically switched only by connecting the cables 5a, 5b to the external terminals 2a, 2b, so that a special manual switching operation is not required, and no switching switch is required. This contributes to downsizing of the device.

〔Example〕

 (A) Description of one embodiment FIG. 2 is a configuration diagram of one embodiment of the present invention.

In the figure, the same components as those shown in FIGS. 1 and 3 are denoted by the same symbols, and 6 is a switching control circuit.
The potential Vcc is applied through the resistor r, and the control terminal 2
switching circuit 3a, which is connected to
3b is switched and controlled in accordance with the input potential (control signal) of the control terminal 2c.

The NTSC cable 5a includes an original cable 50a and an NTSC conversion cable 51a.

The NTSC conversion cable 51a has an open control signal line CS in addition to the signal line NS connected to the original cable 50a.

The S-video cable 5b is different from the original cable 50b.
And an S-video conversion cable 51b.

The S-video conversion cable 51b is the original cable 50b.
And a control signal line CS in a ground state in addition to the signal line VS connected to the control signal line VS.

Fig. 2 (A) to input NTSC composite signal
As shown in (1), the original cable 50a is connected to the NTSC conversion cable 51a, and this cable 5a is connected to the external terminal 2a and the control terminal 2c.

As a result, since the control signal line CS of the cable 5a is open, the switching control circuit 6 is pulled up to the potential Vcc, and a high-level output is given as a control voltage to the switching circuits 3a and 3b composed of electronic switches. As shown in FIG. 2A, the switching circuit 3a is connected to the external terminal 2a, and the switching circuit 3b is connected to the comb filter 4c.

Therefore, as described above, the NTSC signal from cable 50a is
Converted to GB signal.

On the other hand, to input an S-video signal, as shown in FIG. 2 (B), the original cable 50b is connected to the S-video conversion cable 51b, and this cable 5b is connected to the external terminal 2b and the control terminal 2c. Connect to

As a result, the control signal line CS of the cable 5b
Is grounded, the switching control circuit 6 supplies the low level output as a control voltage to the switching circuits 3a and 3b.

Therefore, as shown in FIG. 2B, the switching circuit 3a is connected to the external terminal 2b, and the switching circuit 3b is connected to the switching circuit 3a and the external terminal 2b.
To the side.

Therefore, as described above, the S-video signal from the cable 50b is converted into an RGB signal.

In this way, the switching circuits 3a, 3b are automatically switched to the external terminal connected to the cable by the control signal (open or ground) of the control signal line CS of the cables 5a, 5b.

In this embodiment, since the conversion cables 51a and 51b are used, the original cables 50a and 50b can be used, and the cables themselves can be simplified and contribute to cost reduction.

In this embodiment, since the control signal line CS is opened and grounded to apply the control signal, no special signal needs to be supplied from the input device side, and the cable itself can be used.

(B) Description of Other Embodiments The present invention includes the following embodiments in addition to the above-described embodiments.

In the above-described embodiment, switching of two inputs has been described. However, three or more inputs can be switched by increasing the number of control signal lines or types of control signals.

In the above-described embodiment, the conversion cables 51a and 51b provided with the control signal lines CS are used. However, the control signal lines may be provided on the cables themselves without using the conversion cables.

In this case, various control signals may be supplied from the input device using the control signal line.

In the above embodiment, the video converter has been described as an example, but other devices may be used, and the signal is not limited to the NTSC signal or the S-video signal.

In the above embodiment, the example of switching the signal input has been described. However, the present invention can be used for signal output from an internal circuit.

In the above-described embodiment, the switching control circuit 6 is configured by a potential source and a resistor, but may be configured by a decoder or the like.

Although the present invention has been described with reference to the embodiments, the present invention can be variously modified in accordance with the gist of the present invention, and these are not excluded from the present invention.

〔The invention's effect〕

As described above, the present invention has the following effects.

Since the cable is switched and connected to the internal circuit by the connection of the cable, the trouble of manually operating the changeover switch and the like can be saved.

Further, since the changeover switch is not required, an external space for providing the changeover switch is not required, and the apparatus can be downsized.

[Brief description of the drawings]

 FIG. 1 is a diagram illustrating the principle of the present invention, FIG. 2 is a diagram illustrating the configuration of an embodiment of the present invention, and FIG. In the figure, 2a, 2b ... external terminal, 2c ... control terminal, 3 ... switching part, 4 ... internal circuit, 5a, 5b ... cable, CS ... control signal line.

Continuation of the front page (56) References JP-A 1-320832 (JP, A) JP-A 61-66457 (JP, A) JP-A 2-13867 (JP, A) Jpn. , U)

Claims (1)

(57) [Claims] 1. A connection switching device having a plurality of external terminals connected to a conversion cable to which an external cable is connected, each of which has a plurality of external terminals for receiving signals from different types of external cables. A control terminal corresponding to a type of the external cable connected to the conversion cable and connected to a control signal line provided on the conversion cable; and a signal switching unit configured to switch connection between the plurality of external terminals and an internal circuit. The control cable is connected to the corresponding external terminal by connecting the conversion cable to a corresponding external terminal, and the signal switching unit is connected to the control signal line according to a control signal from the connected control signal line. A connection switching device using a cable connection, which switches to a connected external terminal.