JPS6236379Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an automatic switching termination circuit that can connect and disconnect a terminating resistor to a circuit by simply inserting a plug into a terminal or not. The purpose is to provide

In general, for example, when a VTR is connected to a television receiver equipped with a bridge mechanism (hereinafter referred to as a TV receiver with BR), the video signal is played back by the VTR and displayed on the TV receiver, and when two VTR of 1
When connecting to two BR-equipped TV receivers, playing the video signal on one VTR and monitoring it on the BR-equipped TV receiver, you can dub and record it on the other VTR.
It is necessary to use different terminating resistors for TV receivers with BR. In other words, the impedance needs to be different depending on whether or not a device is connected to the rear of the TV receiver with BR.The former requires a terminating resistor of, for example, 75Ω, while the latter requires a terminating resistor of, for example, 75Ω. is not necessary.

Also, when a certain video signal is displayed simultaneously on multiple TV receivers with BR, a terminating resistor is not required for the TV receiver with BR installed in the previous stage, but the terminal resistor is not required in the TV receiver with BR in the last stage.
TV receivers require a terminating resistor.

In this way, it is necessary to perform impedance matching by turning the terminating resistor on or off depending on the presence or absence of equipment connected to the subsequent stage, but conventionally, this turning on and off has been done using a manual changeover switch.
For this reason, not only is the operation cumbersome, but it is also possible to make a mistake and operate the device with mismatching.It is especially difficult for general users without specialized knowledge to understand, and it is not recommended for general users. There were some drawbacks that made it unsuitable.

The present invention eliminates the above-mentioned drawbacks, and various embodiments thereof will be described below with reference to the drawings.

1 and 2 respectively show a circuit diagram of a first embodiment of an automatic switching termination circuit according to the present invention and a schematic diagram for explaining the usage state of a TV receiver with a BR to which this is applied. Jack 2 is attached to TV receiver 1 with BR.
₁ , 2 ₂ and a terminating circuit path 4 consisting of a terminating resistor 3 is provided. Here jack 2 ₁ terminal 2 ₁₁
and terminal ₂₂₁ of jack ₂₂ are connected to form the hot side of the signal line. Also, jack 2 ₁
The terminal 2 12 of the terminal 2 ₁₂ and the terminal 2 ₂₂ of the jack 2 ₂ are connected to normally closed contacts _a and b, respectively.
and terminal 2 ₂₂ are connected, and a resistor 3 is connected between the connection point between terminal 2 ₁₂ and terminal 2 ₂₂ and the ground. Terminal 2 ₁₃ of jack 2 ₁ and terminal 2 ₂₃ of jack 2 ₂ are both grounded.

On the other hand, the VTR 5 is provided with a plug 6 that can be inserted into the jack ₂₁ of the TV receiver 1 with BR.

Here, as shown in Figure 2, connect the VTR5 to the TV with BR.
When connecting to TV receiver 1 and displaying the video signal played on VTR 5 to TV receiver 1 with BR, insert plug 6 of VTR 5 into jack ₂₁ (jack 2 ₂ is also acceptable) of TV receiver 1 with BR. .

As a result, contacts a and b of jacks 2 ₁ and 2 ₂
is opened, while the contacts of jacks 2 ₂ and 2 ₁
Since ba is closed, the VTR 5 and the terminating resistor 3 are connected between the terminal 7 and the ground. Here, the video signal from the VTR 5 is sent to the jack 2 ₁ ,
The signal is taken out from the terminal 7 via ₂₂ , and is signal-processed inside the TV receiver 1 with BR.

On the other hand, as shown in Figure 3, VTRs 5 and 8 are equipped with Br.
The video signal connected to TV receiver 1 and played back by VTR 5 is monitored by TV receiver 1 with BR, and this is transmitted to VTR 8.
When dubbing recording to
A VTR is installed in the jacks 2 ₁ and 2 ₂ of the TV receiver 1 with BR.
Plug 9 of 8 into jack 2 of TV receiver 1 with BR
₂ and 2 ₁ respectively.

As a result, contact a of jack ₂₁ and contact b of jack ₂₂ are both opened, terminating resistor 3 is not connected between terminal 7 and ground, and VTR 5 and
VTR8 is connected. Here, the video signal from the VTR 5 is taken out from the terminal 7 via the jacks 2 ₁ and 2 ₂ , and is also taken out via the jacks 2 ₂ and 2 ₁ .
Supplied to VTR8.

In this way, simply plug 6 and 9 of VTR 5 and 8.
The terminal impedance of the TV receiver with BR 1 can be changed by simply inserting the terminal impedance into the jacks ₂₁ , ₂₂ of the TV receiver with BR 1, and it is easier to handle than the conventional one, which was changed using a manual switch etc. Moreover, there is no risk of making a mistake in operation.

FIG. 4 shows a circuit diagram of a second embodiment of the circuit of the present invention, in which parts having the same functions as those in FIG. 1 are given the same numbers. In the figure, terminal 2 ₁₁ of jack 2 ₁ and terminal 2 ₂₁ of jack 2 ₂ are connected, and between terminal 2 ₁₂ of jack 2 ₁ and ground, and between terminal 2 ₂₂ of jack 2 ₂ and ground. Terminating resistors 10 ₁ and 10 ₂ are connected between them, respectively.
Similar to the above embodiment, the TV receiver has two jacks.
A terminating circuit 11 is provided which includes terminating resistors 10 ₁ and 10 ₂ and terminating resistors 10 _{1 and} 10 2 . Other configurations are similar to those of the first embodiment.

Here, as shown in FIG. 2, when the plug 6 is inserted into the jacks 2 ₁ , 2 ₂ , the jacks 2 ₁ , 2 ₂
Contacts a and b are opened, and the VTR 5 and terminating resistors 10 ₂ and 10 ₁ are connected between the terminal 7 and the ground. On the other hand, as shown in FIG. 3, when the plug 6 is inserted into the jack ₂₁ and the plug 9 is inserted into the jack ₂₂ , both the contact a of the jack ₂₁ and the contact b of the jack ₂₂ are opened, and the terminal 7 VTRs 5 and 8 are connected between this and ground. Other operations and effects are the same as those in the first embodiment, so their explanation will be omitted.

In addition, when displaying a certain video signal on multiple BR-equipped TV receivers at the same time, the BR-equipped TV receivers
Connect with a lead wire that has plugs 6 and 9 on both ends, and connect it to the jack 2 of the TV receiver with BR in the first stage.
Plug 6 is inserted into ₁ and 2 ₂ to supply video signals, while jack 2 of the final stage BR equipped TV receiver
Do not insert plugs into ₂ and 2 ₁ . This results in
Only the final stage BR-equipped TV receiver can be operated with the terminating resistor connected.

As mentioned above, the automatic switching termination circuit according to the present invention has terminals each having a normally closed contact at both ends of a signal line, and these contacts are connected between the hot side of the signal line and the ground via a terminating resistor. , by inserting a plug into either one of the terminals, the contact of the terminal into which the plug is inserted is opened, and the contact of the other terminal is closed, thereby creating a terminating resistor between the signal line and ground. is connected, but by inserting a plug into each of the two terminals, the contacts of these two terminals are opened, and the terminating resistor is not connected between the signal line and the ground, so it is simply a plug. The impedance of the circuit can be automatically switched depending on whether or not the terminating resistor is inserted into the terminal, making it easier to operate than conventional systems in which the terminating resistor was turned on and off using a manual switch, etc. Moreover, it has the advantage that there is no risk of operational errors and is optimal for general users.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of the first embodiment of the circuit of the present invention, FIGS. 2 and 3 are schematic diagrams for explaining the usage state when the circuit of the present invention is applied to a TV receiver with BR, and FIG. The figure is a circuit diagram of a second embodiment of the circuit of the present invention. 1...TV receiver with BR, 2 ₁ , 2 ₂ ...Jack, 3, 10 ₁ , 10 ₂ ...Terminal resistor, 5, 8...
...VTR, 6, 9...Plug, a, b...Normally closed contact.

Claims (1)

[Scope of utility model registration request] Terminals each having a normally closed contact are provided at both ends of the signal line, the contacts are connected between the hot side of the signal line and the ground via a terminating resistor, and a plug is inserted into either of the terminals. The contact of the terminal into which the plug is inserted is opened, and the contact of the other terminal is closed, so that the terminating resistor is connected between the signal line and the ground. An automatic switching termination circuit configured such that when a plug is inserted into each of the terminals, the contacts of the two terminals are opened and the termination resistor is not connected between the signal line and the ground.