JPH0349485A - External input automatic switching device - Google Patents

Abstract

PURPOSE:To avoid troublesome switching by judging the presence of an external signal input and its priority, selecting automatically an external input terminal whose priority is higher and inputting a signal and connecting the selected terminal to an external output terminal. CONSTITUTION:Changeover switches C1-Cn are switched based on an output from signal detection circuits D1-Dn outputting a control signal when a signal inputted from plural external input terminals A1-An is detected. The signal detection circuits D1-Dn are provided respectively corresponding to the external input terminals A1-An, inhibit circuits E2-En decide the priority of the plural external input terminals and inhibit the transmission of a control signal form the signal detection circuits D1-Dn to the changeover switches C1-Cn when a signal from one of the external input terminals A1-A n is inputted to an external input terminal with lower priority than that of the external input terminals A1-An. Thus, the presence of an external signal and the priority are judged in this way and the connection between the plural external input terminals and one external output terminal is selected and switched automatically.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an external input automatic switching device, and more specifically,
It is used in video equipment having multiple external input terminals, such as televisions, video cassette recorders, AV selectors, etc.

(Prior Art) In video equipment having a plurality of external input terminals, as a method for selecting an external input terminal of an IWA from the plurality of external input terminals, conventionally, a mechanical switch or an electronic switch is provided. ■ A method for the user to manually select one external input terminal as necessary.
A method has been used in which an external input terminal is selected by inserting a jack of an external input device into a desired external input terminal from among a plurality of external input terminals.

(Problem to be Solved by the Invention) However, in the former method (■) described above, when the number of external input terminals increases, the switching operation becomes complicated. Since it is necessary to connect and unplug the jack to perform the switching, there is also the problem that the switching operation becomes complicated.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an automatic external input switching device that eliminates the hassle of switching by automating the selection of a plurality of external input terminals.

(Means for Solving the Problems) In order to solve the above problems, an external input automatic switching device of the present invention has a plurality of external input terminals, one external output terminal, and a plurality of external input terminals. A plurality of open/close switches inserted between each of the external output terminals and the plurality of external input terminals detect signals input from the external input terminals and the external input terminals to which the signals S are input. a signal detection circuit that outputs a control signal to turn on an open/close switch provided between the output terminal and the plurality of external input terminals; If a signal is given to an external input terminal with a lower priority than that external input terminal when the external input terminal is When a signal is being input, if a signal is given to an external input terminal with a higher priority than that external input terminal, the transmission of the signal from the one external input terminal is prohibited, and the priority is and a prohibition circuit that sends out a signal applied to an external input terminal of a higher order.

(Function) Multiple external input terminals and one external output terminal are connected via open/close switches, and the open/close operation of this open/close switch is performed when signals input from multiple external input terminals are detected. This is performed based on the output of a signal detection circuit that sends out a control signal to turn on the open/close switch provided between the external input terminal and the external output terminal to which the signal is input. This signal detection circuit is usually provided corresponding to each external input terminal. In addition, the prohibition circuit determines the priority order of multiple external input terminals, and when a signal is input from one external input terminal, the prohibition circuit determines the priority order of multiple external input terminals. When a signal is input, it operates to prohibit the signal detection circuit from sending out a control signal to the open/close switch provided between the external input terminal and the external output terminal below it. Therefore, when a signal is input from one external input terminal and output to an external output terminal via the corresponding open/close switch, the signal is sent to an external input terminal with a lower priority than that external input terminal. When a signal is input, the open/close switch provided between the lower external input terminal and the external output terminal will not turn on due to the prohibition circuit, so the signal input from the lower external input will be It will not be sent to the external output terminal.

That is, in this case, the above-mentioned 1 which has a higher priority
The signals from the two external input terminals will continue to be output to the external output terminal.

On the other hand, when a signal is input from one external input terminal and is output to an external output terminal via the corresponding open/close switch, the signal is sent to an external input terminal with a higher priority than that external input terminal. When a signal is input, the open/close switch provided between the external input terminal and the external output terminal is turned on based on the control signal from the signal detection circuit.
At the same time, the prohibition signal from the prohibition circuit turns off the open/close switch provided between the one external input terminal and the external output terminal, which have the lowest priority. Instead of the signal input from the external input terminal with a lower priority, the signal input from the external input terminal with a higher priority is output to the external output terminal.

In addition, when input of a signal to one external input terminal is finished, all external input terminals enter the input standby state, so when a signal is input to any external input terminal after that, the Since the open/close switch connected between the external input terminal and the external output terminal is turned on, the signal input to the external input terminal is output to the external output terminal.

As described above, the external input automatic switching device of the present invention determines the presence or absence of signals from the outside and the priority order for a plurality of external input terminals, and switches the plurality of external input terminals based on the determination result. The connection between the output terminal and one external output terminal is automatically selected and switched.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the electrical structure of the automatic external input switching device of the present invention.

In the figure, A l+ A z. Aff+...
A, are external input devices X r. Xt. X
z. ...Multiple external input terminals connected to XI,
B is one external output terminal connected to the input terminal of video equipment Y. Each external input terminal A In A t. A
s. ...A7 is the open/close switch C r, C
z, Cs, . . . are connected to external output terminal B via C7. In addition, each external input terminal A I+ A
z. A s. ... Aゎ is each signal detection circuit D + . which detects the input signal. Dt. Ds,...
D7, and the output of the signal detection circuit D1 is sent as an opening/closing control signal to the corresponding opening/closing switch C.
．． is given to the opening/closing control input. In addition, other signal detection circuits D,,D! , . E s.・・・
-E7, each open/close switch C2 . Cs.
...It is guided by the opening/closing control input of C7.

In addition, the output of the signal detection circuit mountain is output from each inhibition circuit E t.
E s. ...E. The output of the prohibition circuit E2 is guided to the control input of the other prohibition circuits Es,...E7, and the output of the prohibition circuit E3 is guided to the control input of the prohibition circuit E.
It is led to the control inputs of the other inhibition circuits Ea, . . . , except for E7. In this way, the output of the prohibition circuit located at the top in the drawing is sequentially guided to the control inputs of all the prohibition circuits located at the bottom in the drawing, so that the control input of the prohibition circuit Ea located at the bottom is as follows. The output of the signal detection circuit D1 and the output of all the upper-level prohibition circuits [specifically, (n-
1) The structure is guided by the book.

The signal detection circuits D, . Dt. Ds. ...D7 is the external input terminal A+. Az. A s. -A,
From the video signal S a l rS m 2 + ...S
When un is input, rH, 3 level signals are output, and the video signal S al+ SS! +...S
When an is not input, it is configured to output a "L" level signal, and the on/off switch Cr
Cz Cs...C7 is set to be in the ON state when an "H" level signal is applied to its opening/closing control input.

Further, the prohibition circuit E z. E 3. ... Efi has at least one of its control inputs set to "H".
” level signal is being led, the signal detection circuit D z. D3. ...D, output is open/close switch C
z, C s, . . . is configured to prohibit its output so that it is not applied to C1.

That is, such prohibition circuits E z, E 3,...
・E. By connecting each external input terminal A,,A. ,A
．． , . . . 80, priority is set for connection to external output terminal B. In other words, a signal input from one external input terminal is prohibited from being output when a signal is input from an external input terminal located above it in the drawing, and a signal is prohibited from being output from an external input terminal located below it in the drawing. Since the output continues when an input is received, the external input terminal A. is the lth priority input terminal, the next external input terminal A2 is the second priority input terminal, and the lowest external input terminal A1 is the nth priority input terminal.

Figure 2 shows the signal detection circuits Dr, Dz, D3, .
. . . An example of a specific circuit configuration of D7 is shown.

In the figure, external input terminal A. (or A z. A
s. ...A. ) is connected to the diode D.
is connected to the cathode of diode D. The anode of is connected to the base of transistor Q1 via resistor RI and capacitor CI. The terminal of the transistor Q is connected to the power supply voltage ycc, and the collector is grounded through the resistor R and is also connected to the output terminal 2. Also, transistor Q
．． A bias resistor Rt is connected between the emitter and base of.

With the above structure, when no signal is input from the input terminal 1, the transistor Q1 is turned off, and as a result, an "L" level signal is output from the output terminal 2. When a signal is input from the input terminal 1, a peak detection circuit consisting of a diode D6, a resistor R1, and a capacitor C1 generates a signal from the transistor Q. As a result, the base potential of the transistor Q1 is reduced and the transistor Q1 is turned on, and as a result, a signal of rH level is output from the output terminal 2.

Figure 3 shows the prohibition circuit E. ,E. , . . . shows an example of a specific circuit configuration of E7.

In the figure, signal detection circuit D. (or D,...D
stomach)? The terminal 3 into which these signals are input is connected to the output terminal 4 which is connected to the opening/closing control input of the opening/closing switch Cz (or C3+...C.) via the resistor R4, and
The output side of the resistor R4 is connected to the collector of a transistor Q2 whose terminal ξ is grounded. Moreover, the plurality of input terminals a In a 28...an-■ are connected to the plurality of diodes D. ,D.
,...I) connected to the anode of n-+,
The cathodes of the diodes DI, Dz, . . . D n-+ are connected to the transistors Q. connected to the base of. That is, multiple diodes D. ,D. ,...D7-1, O having a plurality of input terminals al+a2,...an-1
The R circuit is configured. However, this input terminal aI,
a! + ”' a n − 1 is the prohibition circuit E..E.
,・E. Since it corresponds to each control input of
The circuit shown in FIG. 3 has a circuit structure corresponding to the prohibition circuit E7. Therefore, other prohibited circuits E2, E
s. ... In Ea-+, it is necessary to provide a structure in which the number of input terminals and the number of diodes shown in FIG. 3 correspond to the respective control inputs.

With the above configuration, the signal from the signal detection circuit D is given to the opening/closing control input of the opening/closing switch C through the terminal 3, the resistor R4, and the output terminal 4, and the opening/closing switch C7 is turned ON.
When the input terminals a l, a t,
...at least one input terminal of a1-1 is connected to "
When a "H" level signal is input, the transistor Q2 is turned on, so that the signal detection circuit D. The signal from the transistor Qt is led to ground through the transistor Qt, and is not applied to the open/close control input of the open/close switch C, l. As a result, the open/close switch C7 maintains the OFF state, so that the signal input to the external input terminal A7 is not output to the external output terminal B.

Next, the operation of the external input automatic switching device having the above structure will be explained.

Now, as an example, the third priority external input terminal A
A signal is input from external input device X, connected to ,
Consider the case where no signals are input to the other external input terminals.

In this case, the signal from the external input terminal A3 is detected by the signal detection circuit D3 and input to the input terminal 3 of the inhibition circuit E3. At this time, each control input a of the inhibition circuit E,
l. Since no "H" level signal is input to a2, transistor Q2 is in the OFF state,
Therefore, the signal input to input terminal 3 is transmitted through resistor R4
, is applied to the opening/closing control input of the opening/closing switch C, via the output terminal 4. As a result, the open/close switch c3 is turned on, so the signal input from the external input terminal A3 is output to the external output terminal B via the open/close switch c3, and is connected to the external output terminal B. It will be sent to video equipment Y. Further, the signal output from the prohibition circuit E3 is transmitted to the prohibition circuits E4, . . . , which are connected to external input terminals Am, . . . E7, these inhibition circuits E4, . . . E7 are connected to each signal detection circuit D4 . . . . operates to inhibit the signal output from D7 (that is, it is led to ground by the transistor Q2, and the on/off switch Ca.
...operates so that it is not applied to each control input of C7)
are doing. In this state, the external input terminals A4, . . . , the external input terminals A4.・
...A. When a signal is input to , each inhibition circuit E4 connected to the lower external input terminal Aa, . . . A7
,...En prohibits signal output from each signal detection circuit D4,...D,, so the corresponding open/close switch C4. ...C, will maintain the OFF state. As a result, the signal input from the third priority external input terminal A is successively output to the external output terminal B.

Next, in a state where the signal input from the third priority external input terminal A is output to the external output terminal B,
Consider a case where a signal is input to the external input terminal A2, which has a higher priority than the external input terminal A, which has the third priority. In this case, the signal from the upper external input terminal Aa is detected by the signal detection circuit D2 and input to the input terminal 3 of the inhibition circuit E2. At this time, since the "H" level signal is not input to the control input a1 of the inhibition circuit E2, the transistor Q2 is in the OFF state, and therefore the signal input to the input terminal 3 is transmitted to the resistor R4,
It is applied to the opening/closing control input of the opening/closing switch C2 via the output terminal 4.

As a result, the open/close switch C2 is turned on, so the signal input from the external input terminal A2 is output to the external output terminal B via the open/close switch C8, and the video signal connected to the external output terminal B is output. It will be sent to device Y. At this time, since the signal output from the output terminal 4 of the prohibition circuit Et is given to the control input of the prohibition circuit E, which is connected to the external input terminal A of the third priority, the prohibition circuit E is It operates to inhibit signal output from the signal detection circuit D3 connected at the preceding stage. As a result, the open/close switch C3, which had been in the ON state until then, is switched to the OFF state, and the transmission of the signals from the external input terminals A and 3 with the third priority, which had been sent out to the external output terminal B, is stopped. That will happen. That is, in this case, instead of the signal input from the external input terminal A, which has a lower priority, the external input terminal A2, which has a higher priority,
The signal input from the terminal B is output to the external output terminal B.

Furthermore, when the input of the signal from the external input device X to the external input terminal A is completed, all the prohibited circuits Ez,
E s. ...Since E returns to its initial state, J
All external input terminals A i , A z , A 's.
...80 enters the input standby state. After that, any external input terminal A r , A z . A s.・
...When a signal is input to 80, the external input terminals A1, Az. A s. ...A. Open/close switch CI Ct C connected between C and external output terminal B
s...Since C7 is turned on, its external input terminal A
r. A t, A z. ...The signal input to A7 will be output to external output terminal B.

(Effects of the Invention) The automatic external input switching device of the present invention determines the presence or absence and priority of external signal input for a plurality of external input terminals, and determines whether the priority is on the higher side and the signal is on the higher side. Since the input external input terminal is automatically selected and connected to the external output terminal, it is possible to automatically switch to the specified external input terminal, eliminating the need for manual switching unlike conventional devices. becomes.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the electrical structure of the external input automatic switching device of the present invention, Fig. 2 is a circuit diagram showing a more specific structure of the signal detection circuit, and Fig. 3 is a block diagram showing the more specific structure of the signal detection circuit. FIG. 3 is a circuit diagram showing a specific configuration. AI, Al,...A7...External input terminal B...Input terminal

Claims (1)

[Claims] 1) A plurality of external input terminals, one external output terminal, and a plurality of opening/closing devices inserted between each of the plurality of external input terminals and the external output terminal. a switch; detects a signal input from the plurality of external input terminals, and outputs a control signal to turn on an open/close switch provided between the external input terminal and the external output terminal to which the signal is input; A signal detection circuit, which determines the priority order of the plurality of external input terminals, and when a signal is input from one external input terminal, transmits the signal to an external input terminal having a lower priority than that external input terminal. is given, prohibits the sending of the signal given to the lower external input terminal, and when a signal is being input from one external input terminal, the signal given to the external input terminal with a higher priority than that external input terminal is prohibited from being sent. and a prohibition circuit that prohibits transmission of the signal from the one external input terminal when a signal is applied to the external input terminal, and transmits the signal applied to the external input terminal having a higher priority. An external input automatic switching device characterized by: