JPH0583748A - Video cable connection state check device in av system - Google Patents

Abstract

PURPOSE:To provide a message representing at which of two AV equipments at output and input sides a video cable is disconnected. CONSTITUTION:A synchronizing signal extract section 4 is connected to a video output terminal 2 and a mechanical switch 2a is provided to the check device. When an extract signal S3 is lower than a prescribed level and the mechanical switch 2a is closed, it is discriminated that the connection state is normal and when the extract signal S3 is higher than a prescribed level and the mechanical switch 2a is closed, it is discriminated that a cable is disconnected at a 2nd AV equipment side Y, and it is discriminated that a cable is disconnected at a 1st AV equipment side X, when the mechanical switch 2a is opened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal output side such as a connection between a television receiver and a video tape recorder, a connection between a television receiver and a laser disc player, and a connection between television receivers. For checking the connection state between the AV device and the video cable in an AV system in which the first AV device and the second AV device on the video signal input side are connected via a video cable (including an optical cable) Regarding

[0002]

2. Description of the Related Art As a conventional video cable connection state checking device of this type, a mechanical switch that operates in a video cable connection state is provided at the video output terminal of a first AV device on the video signal output side. There is a device which outputs a cable disconnection detection signal when the physical switch is in a non-operating state and turns on an LED to notify the user that the cable is disconnected.

[0003]

However, in the case of such a conventional example, even if the video cable is disconnected from the video input terminal of the second AV equipment on the video signal input side, this cannot be detected at all. there were.

For this reason, for example, when an attempt is made to record a video signal on a VTR by recording, even if the video cable is disconnected from the VTR on the video signal input side, the user does not notice this and the video recording is performed. There was a problem that failed.

When the mechanical switch is in a bad state, it is erroneously determined that the video cable is disconnected even though the video cable is normally connected, or the video cable is normally connected even when the video cable is disconnected. There was also the problem of making an erroneous decision.

Further, even when the mechanical switch is in a good state, it merely detects whether or not the video cable is plugged into the video output terminal, and apparently even if it is plugged in, It was impossible to distinguish whether the connection was normal or whether there was an abnormality such as poor contact.

In particular, when the video cable is an optical cable, if the light emitting portion and the light receiving portion are misaligned or the reflection efficiency is deteriorated, even if the video signal is input, the signal is input. There was a problem that the initial function could not work normally because the level was lower than the regular level.

The present invention was devised in view of the above circumstances, and its first object is not to rely solely on mechanical switches, but to use the first AV equipment on the video signal output side. The reliability of the determination is improved by determining the connection state based on the change in the level of the signal that is actually output. The second purpose is to detect the first AV when the video cable is disconnected. It is to be able to distinguish whether it has come off on the device side or the second AV device side,
A third object is to enable determination of whether the connection state is substantially good or not, not whether the connection state is apparently good or bad.

[0009]

A first AV according to the present invention
The video cable connection status check device in the system connects a first AV device on the video signal output side and a second AV device on the video signal input side via a video cable A
In the V system, a synchronizing signal extracting section is connected to the video output terminal of the first AV device, and when the level of the extracting signal by the synchronizing signal extracting section is lower than a predetermined value, a connection state normal signal is output, When the level of the extraction signal is higher than the predetermined value, a cable connection state determination means for outputting a cable disconnection detection signal is provided.

A video cable connection status check device in a second AV system according to the present invention is a video signal output side first AV device and a video signal input side second AV device.
In an AV system in which a device is connected via a video cable, a mechanical switch that connects the video signal output terminal of the first AV device with a sync signal extracting unit and operates in a state in which the video cable is connected to the video output terminal Is provided, when the level of the extraction signal by the synchronization signal extraction unit is lower than a predetermined value and the mechanical switch is in the operating state, a connection state normal signal is output, and the level of the extraction signal is higher than the predetermined value. When it is high and the mechanical switch is in the operating state, the second AV device side outputs an input side disconnection detection signal indicating that the video cable is disconnected, and the mechanical switch is in the non-operating state. In this case, the cable for outputting the output side disconnection detection signal indicating that the video cable is disconnected on the side of the first AV device. In which characterized in that a connection state determining means.

Further, the video cable connection state checking device in the third AV system according to the present invention comprises a first AV device on the video signal output side and a second A on the video signal input side.
In an AV system in which V equipment is connected via a video cable, a synchronization signal extracting section is connected to the video input terminal of the second AV apparatus, and the level of the extraction signal by the synchronization signal extracting section is higher than a predetermined value. In this case, a cable connection state determination means is provided, which outputs a connection state normal signal in this case, and outputs a connection state defect detection signal in the case where the level of the extraction signal is lower than the predetermined value.

[0012]

[Operation] The first video cable connection state checking device is
If the video cable is normally connected between the first AV device and the second AV device, the first AV device
The video signal output from the video output terminal of the device is divided into the video output terminal side and the video input terminal side of the second AV device, so that the level of the output video signal becomes low. It is a thing.

Since the level itself of the output video signal varies according to the change in luminance, it is an uncertain factor, but the level of the sync signal included in the output video signal is stable. Therefore, the synchronization signal is extracted and used as a reference for determining the cable connection state.

That is, when the level of the sampling signal is lower than the predetermined value, it is determined that the connection state of the video cable to both the first and second AV devices is normal, and when the level is higher than the predetermined value, the video cable is not connected. It is determined that it is in the disengaged state.

According to the first video cable connection state checking device, whether the video cable is normally connected or disconnected even if the mechanical switch is in a bad state or does not have a mechanical switch. It is judged correctly.

Further, in the case of the second video cable connection status check device, a mechanical switch provided at the video output terminal is also used so that the level of the sampling signal is higher than a predetermined value and the mechanical switch is in the operating status. In some cases, the second AV device side determines that the video cable is disconnected, while when the mechanical switch is in the non-operating state, the first AV device side determines that the video cable is disconnected. ..

Further, the third video cable connection state checking device is arranged so that, even if the video cable is connected satisfactorily in appearance, if there is a contact failure or a positional deviation between the light emitting portion and the light receiving portion, the This is because the video signal input to the video input terminal of the second AV device is deteriorated and its level is lowered.

Also in this case, a synchronization signal which is stable against a change in luminance is used as a criterion for the determination. That is,
The sync signal extracting portion is connected to the video input terminal of the second AV device, and when the level of the extraction signal thereby is higher than a predetermined value, it is determined that the substantial connection state of the video cable to the video input terminal is normal. When it is lower than the predetermined value, it is determined that there is a defect in the substantially connected state (such as contact failure or positional deviation between the light emitting unit and the light receiving unit).

Therefore, according to the third video cable connection status check device, not only the appearance connection quality but also the above-mentioned substantial connection status can be determined.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a video cable connection status checking device in an AV system according to the present invention will be described below in detail with reference to the drawings.

First Embodiment FIG. 1 is a block circuit diagram showing a main part of a video cable connection state check device according to a first embodiment of the present invention.

In the figure, X is a first AV device on the video signal output side, Y is a second AV device on the video signal input side, and Z is a connection between the first AV device X and the second AV device Y. It is a video cable to do.

The first AV equipment X includes the following elements. Q1 is a transistor for video output buffer, R
1 is its emitter resistance, R2 is an output resistance, C1 and C2 are coupling capacitors, and R3 is a grounding resistance. Reference numeral 2 is a video output terminal, 2a is a mechanical switch that closes when the pin terminal 12a of the video cable Z is inserted and connected to the video output terminal 2, and 4 is a coupling capacitor C2 to the video output terminal 2.
The reference numeral 6 is a waveform shaping section connected to the next stage of the sync signal extracting section 4. The waveform shaping section 6 is composed of, for example, a one-shot multivibrator.

A part of the video signal to be output from the video output terminal 2 is input to the sync signal extracting section 4 as a video signal S1 via a coupling capacitor C2, and a video signal is output by a sync separation circuit (not shown). The more separated horizontal synchronizing signal is input as the sampling timing signal S2. Then, the synchronization signal extracting unit 4
Is adapted to extract the horizontal synchronizing signal included in the video signal S1 in synchronization with the sampling timing signal S2 and output the sampling signal S3 to the waveform shaping section 6.

Reference numeral 8 is a microcomputer, and this microcomputer 8 has a video output level monitoring means 8a.
And a cable disconnection portion determining means 8b, and a cable connection state determining means 8A and a message sending means 8B.
Is included.

Reference numeral 10 denotes a video input terminal in the second AV device Y, to which the pin terminal 12b of the video cable Z is inserted and connected. Video input terminal 1
A cable core grounding resistance R4 (75Ω) is connected to 0.

Next, the operation of the video cable connection status check device having the above-mentioned configuration will be described.

Now, the pin terminal 12 of the video cable Z
a is plugged and connected to the video output terminal 2 of the first AV device X, whereby the mechanical switch 2a is closed and the pin terminal 12b is plugged and connected to the video input terminal 10 of the second AV device Y. It has been done.

The video signal output from the video output buffer transistor Q1 is shunted to the sync signal extracting section 4, and the cable core grounding resistance R4 is supplied from the video output terminal 2 via the video cable Z and the video input terminal 10.
Will be diverted to. Therefore, the level of the video signal S1 flowing into the sync signal extracting section 4 is small as in the first half of FIG. Similarly, the sync signal is also small.

The sync signal extracting section 4 tries to extract the sync signal from the video signal S1 at the input timing of the extraction timing signal S2. However, since the level of the sync signal is small, the sync signal is not actually extracted. The sampling signal S3 input from the synchronization signal extracting unit 4 to the waveform shaping unit 6 and the signal S4 output from the waveform shaping unit 6 are both stable at a zero level.

Therefore, the signal S5 output from the video output level monitoring means 8a in the cable connection state determining means 8A of the microcomputer 8 to the cable disconnection portion determining means 8b becomes "L" level. Also, the signal S6 input from the mechanical switch 2a is
Since "a" is closed and connected to the ground line, it also becomes "L" level.

When the two input signals S5 and S6 are both at "L" level, the cable disconnection part determining means 8b outputs the video cable Z to the first AV equipment X as the signal S7 to the message sending means 8B. "Connection status normal signal" indicating that it is correctly connected to the second AV device Y
Is output. In this case, the message sending means 8B outputs nothing as the signal S8 for the message part (not shown).

Next, it is assumed that the pin terminal 12a of the video cable Z is disconnected from the video output terminal 2 of the first AV device X. Then, the mechanical switch 2a is opened, and the signal S6 input from the mechanical switch 2a to the cable disconnection portion determination means 8b of the microcomputer 8 is changed from "L" level to "H" as shown in the central portion of FIG. Switch to level.

In this case, the cable disconnection portion determining means 8b
Is a signal S7 to the message sending means 8B,
An "output side disconnection detection signal" indicating that the video cable Z has disconnected on the side of the first AV device X is output.

Then, the message sending means 8B outputs a message M1 indicating "the video cable is not connected to the first AV device" as a signal S8 for a message part (not shown). As the message M1, the corresponding LED may be turned on, or characters may be displayed on the display screen by controlling the on-screen display circuit.

Since the video cable Z is disconnected,
The level of the video signal S1 input to the sync signal extracting unit 4, and thus the level of the sync signal, increases as shown in the central portion of FIG. 2, and the sync signal is extracted from the video signal S1 in synchronization with the extraction timing signal S2. Accordingly, the output signal S4 from the waveform shaping section 6 becomes "H" level, and the signal S5 from the video output level monitoring means 8a to the cable disconnection part determining means 8b also becomes "H" level. But this is not directly related. However, this may be used.

Next, the video cable Z is not on the side of the first AV device X, but on the video input terminal 10 of the second AV device Y.
It is assumed that the pin terminal 12b has come off. In this case, the mechanical switch 2a maintains the closing operation state, and the input signal S6 to the cable disconnection portion determination means 8b remains at "L" level. On the other hand, from the video input terminal 10 to the pin terminal 12
Since b is removed, the cable core ground resistance R4 is the first
The video output terminal 2 of the AV device X is disconnected.

As a result, all the video signals output from the video output buffer transistor Q1 flow into the sync signal extracting section 4, and the level of the video signal S1 increases as shown in the latter half of FIG. 2 ( Doubled). Since the level of the video signal S1 and hence the level of the sync signal increases, the sync signal extracting unit 4
Is the video signal S in synchronization with the sampling timing signal S2.
The synchronization signal is extracted from 1 and the signal S3 from the synchronization signal extraction unit 4 to the waveform shaping unit 6 becomes a pulse signal synchronized with the extraction timing signal S2.

Since the waveform shaping section 6 is configured as a one-shot multivibrator, it outputs the "H" level signal S4 as long as this pulse signal continues. This is because the pulse interval of the horizontal synchronizing signal is 63.556 μsec, but the holding time of the waveform shaping section 6 is set longer than this.

The signal S5 output from the video output level monitoring means 8a is at "H" level, and is maintained at "H" level as long as the pulse signal continues.

In this way, one input signal S5 to the cable disconnection portion determination means 8b becomes "H" level and the other signal S6 remains "L" level.
The cable disconnection portion determination means 8b outputs, as the signal S7 to the message transmission means 8B, an "input side disconnection detection signal" indicating that the video cable Z has disconnected on the second AV equipment Y side.

Then, the message sending means 8B outputs a message M2 indicating that "the video cable is not connected to the second AV device" as a signal S8 for a message part (not shown), and turns on the corresponding LED. Or display characters on the display screen.

As described above, when the video cable Z is disconnected, a message clearly indicating which side of the first AV device X and the second AV device Y is disconnected, so that the connection is immediately made. can do.

Therefore, for example, it is possible to avoid a recording error when the reserved recording is performed by the VTR. In addition, when you press the record button or the reservation button, this circuit works,
It is preferable to give a message when the connection status is bad.

By the way, the first embodiment corresponds to the second video cable connection state checking device according to the present invention, but the mechanical switch 2a is omitted from the first embodiment, but the present invention is not limited thereto. This corresponds to the first video cable connection status check device.

Second Embodiment FIG. 3 is a block circuit diagram showing a main part of a video cable connection state check device according to a second embodiment of the present invention. In FIG. 3, the first AV device X on the video signal output side is simply illustrated, but it may be considered that the first AV device X has the same configuration as that of the first embodiment or a different configuration. May be.

In the figure, 20 is a video input terminal into which the pin terminal 12b of the video cable Z is inserted and connected, R5 is a cable core grounding resistance, C3 and C4 are coupling capacitors, and R is a capacitor.
6 is a resistor for surge input, 22 is a sync signal extracting portion,
Reference numeral 24 is a microcomputer, 24A is a sampling signal judging means, 24B is a message sending means, and 26 is a video input switching IC. The extraction signal determination means 24A constitutes a cable connection state determination means.

Next, the operation of this video cable connection status check device will be described.

It is assumed that the video cable Z is correctly connected to both the first AV device X and the second AV device Y. Second
AV device Y side, the pin terminal 1 of the video cable Z
This means that 2b is inserted and connected to the video input terminal 20 without a contact failure.

The video signal output from the video output terminal 2 of the first AV device X and input to the video input terminal 20 via the video cable Z passes through the coupling capacitor C3 and the surge input-compatible resistor R6 to switch the video input. The signal S16 input to the IC 26 for input and the signal S11 input to the synchronization signal extracting unit 22 via the coupling capacitor C4 are shunted.

Since the video cable Z is properly connected, the level of the video signal S11 becomes a normal and relatively high level as shown in the first half of FIG. Extraction timing signal S12 input from a sync separation circuit (not shown)
In synchronism with, the sync signal of the video signal S11 is extracted,
The pulse signal S13 is supplied to the sampling signal determination means 24a.
Is entered as.

In this case, the sampling signal judging means 24a
Determines that the connection state of the pin terminal 12b with respect to the video input terminal 20 is a normal state without contact failure, and outputs a "connection state normal signal" as the signal S14 to the message sending means 24b. As a result, the message sending means 24b does not output the message to the message part.

Next, assume that the connection state of the pin terminal 12b with respect to the video input terminal 20 is poor contact. Then,
The level of the video signal input to the video input terminal 20 becomes lower than the normal level as shown in the latter half of FIG. Similarly, the sync signal is also small.

Therefore, the sync signal extracting unit 22 does not extract the sync signal from the video signal S11.
The signal S13 switches to a stable state at zero level.
Then, the sampling signal determining means 24a outputs a "connection state defect detection signal" as the signal S14 to the message sending means 24b. As a result, the message sending means 24b
Outputs a message M3 to the effect that the "input video signal is not at a normal level" to a message part (not shown). That is, the corresponding LED is turned on or the on-screen display is driven to display characters on the display screen.

When the video cable Z is an optical cable, the signal level becomes small due to the deterioration of the reflection efficiency, the position shift between the light emitting portion and the light receiving portion, and the same message as above is issued. In the case of an optical cable, a photoelectric conversion circuit is used. For signal level detection,
It is also conceivable to perform light amount detection using a beam splitter.

[0056]

According to the first video cable connection state check device of the present invention, the level of the output video signal becomes low in the normal connection state, and the level of the sync signal is stable even when the brightness changes. By taking advantage of the fact that the sync signal is extracted from the output video signal, it is determined that the video cable is disconnected when the level of the extracted signal is higher than a predetermined value. Also, even without a mechanical switch, it is possible to correctly determine whether the video cable is normally connected or disconnected, and the reliability of the connection state determination can be improved.

Further, according to the second video cable connection state check device of the present invention, the mechanical switch provided at the video output terminal is also used, and the level of the extraction signal is higher than a predetermined value and the mechanical switch operates. While the second AV device side determines that the video cable is disconnected when in the state, the first is when the mechanical switch is in the non-operating state.
Since it is determined that the video cable is disconnected on the AV device side, it is clear if the video cable is disconnected whether it is the first AV device side or the second AV device. Can be distinguished.

Further, according to the third video cable connection state check device of the present invention, not only the appearance connection state of the video cable is good but also the contact failure, the positional deviation between the light emitting portion and the light receiving portion, and the like. It is also possible to make a determination as to whether or not the actual connection state such as the presence or absence is good or bad.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing a main part of a video cable connection status check device in an AV system according to a first embodiment of the present invention.

FIG. 2 is a waveform diagram for explaining the operation of the first embodiment.

FIG. 3 is a block circuit diagram showing a main part of a video cable connection status check device in an AV system according to a second embodiment of the present invention.

FIG. 4 is a waveform diagram for explaining the operation of the second embodiment.

[Explanation of symbols]

 X First AV device Y Second AV device Z Video cable 2 Video output terminal 2a Mechanical switch 4 Synchronous signal extraction unit 6 Waveform shaping unit 8 Microcomputer 8A Cable connection state determination unit 8a Video output level monitoring unit 8b Cable disconnection Part determination means 8B Message transmission means 10 Video input terminal 20 Video input terminal 22 Synchronous signal extraction section 24 Microcomputer 24A Extraction signal determination means 24B Message transmission means

Claims (3)

[Claims] 1. An AV system in which a first AV device on the video signal output side and a second AV device on the video signal input side are connected via a video cable, wherein a video output terminal of the first AV device is provided. Connect the sync signal extraction unit, output a connection status normal signal when the level of the extraction signal by this synchronization signal extraction unit is lower than a specified value, and disconnect the cable when the level of the extraction signal is higher than the specified value. A video cable connection state check device in an AV system, characterized in that a cable connection state determination means for outputting a detection signal is provided. 2. An AV system in which a first AV device on the video signal output side and a second AV device on the video signal input side are connected via a video cable, wherein a video output terminal of the first AV device is provided. A mechanical switch that operates in a connected state of the video cable is provided to the video output terminal while connecting the synchronization signal extracting unit, and the level of the extraction signal by the synchronization signal extracting unit is lower than a predetermined value and the mechanical switch is When in the operating state, the connection state normal signal is output, and when the level of the extraction signal is higher than the predetermined value and the mechanical switch is in the operating state, the video cable is connected to the second AV device side. When the mechanical switch is in the non-operating state, it outputs the input side disconnection detection signal indicating the disconnection, and the first AV device side A video cable connection state check device in an AV system, further comprising cable connection state determination means for outputting an output-side disconnection detection signal indicating that the video cable is disconnected. 3. An AV system in which a first AV device on the video signal output side and a second AV device on the video signal input side are connected via a video cable, wherein a video input terminal of the second AV device is provided. Connect the sync signal extraction unit, output a connection status normal signal when the level of the extraction signal by the synchronization signal extraction unit is higher than a predetermined value, and connect the connection signal when the level of the extraction signal is lower than the predetermined value. A video cable connection state check device in an AV system, characterized in that a cable connection state determination means for outputting a defect detection signal is provided.