JP5349158B2 - Input signal switching device - Google Patents

Description

  The present invention relates to an input signal switching device suitable for, for example, switching an input source of a video / audio device, in which two or more systems of connectors are mounted.

AV output of AV (Audio Visual) devices such as commercially available video cameras and TV game machines is output via two types of connectors of different specifications such as an RCA plug or a stereo mini club depending on the model.
For this reason, it is desirable that an in-vehicle display or an RSE (rear seat entertainment) device that connects these AV devices to display video content includes at least the two types of external AV input terminals described above.

By the way, when an AV signal is input to both of the two AV input terminals described above, it is necessary to have a function of selecting only one of the signals and connecting it to the reproduction circuit at the subsequent stage.
For this reason, conventionally, a priority is given to one of the plurality of types of video equipment, and when this video equipment is in use, an AV signal from which the AV signal from the priority video equipment can be automatically selected and switched. An automatic switching device is known (see, for example, Patent Document 1).

  In addition, a plurality of AV input terminals are provided. Among them, a function of selecting only one AV signal and outputting it to a subsequent playback circuit is provided. A video signal detection circuit is provided after each video signal terminal of each set input. There is also known an external input automatic switching device realized by providing it. According to this external input automatic switching device, when a plurality of video signal inputs are detected, the AV input signal having the highest priority is selected based on the selection priority set in advance for each input group. It is controlled (see, for example, Patent Document 2).

JP-A-5-145847 Japanese Patent Laid-Open No. 3-49485

  However, both of the above-mentioned Patent Documents 1 and 2 require a video signal detection circuit for detecting the presence / absence of a video signal input, which causes a problem in terms of cost.

  The present invention has been made to solve the above-described problems, and provides an input signal switching device that eliminates the need for a video signal detection circuit and realizes switching of an input signal at a low cost by adding a small amount of hardware. For the purpose.

In order to solve the above-described problem, the input signal switching device according to the present invention has two input terminals and a signal input from each input signal source via the two input terminals. Signal switching means for outputting a signal of one input signal source to a circuit connected to a subsequent stage through one output terminal by a resistor connected in series according to the priority order.

  According to the input signal switching device of the present invention, the video signal detection circuit is unnecessary, and switching of the input signal can be realized at a low cost by adding a little hardware.

It is a figure which shows the circuit structure of the input signal switching apparatus which concerns on Embodiment 1 of this invention. It is the figure quoted in order to demonstrate the operation principle of the input signal switching apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the circuit structure of the modification of the input signal switching apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the circuit structure of the input signal switching apparatus which concerns on Embodiment 2 of this invention. It is the figure quoted in order to demonstrate the operation | movement principle of the input signal switching apparatus which concerns on Embodiment 2 of this invention.

Hereinafter, an input signal switching device according to an embodiment of the present invention will be described in detail with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a circuit configuration of an input signal switching device according to Embodiment 1 of the present invention. As shown in FIG. 1, an input signal switching device 1 according to Embodiment 1 of the present invention is connected between input signal sources 2 and 3 and a playback device (not shown). Are connected through AV input connector group J1 (5) and AV input connector group 6 (L, R, V), and are connected to playback equipment through output terminals Lo, Ro, Vo.

Each AV input connector group J1 (5), J2 (6) includes two terminals (L, R) for audio signals and one video signal terminal (V). Here, a stereo mini plug is used as the AV input connector group J1 (5), and an RCA cable is used as the AV input connector group J2 (6).
The AV input connector groups J1 (5) and J2 (6) described above may not include the video signal terminal (V).

In FIG. 1, symbol L ₁ is an audio L signal from the input signal source 2, symbol R ₁ is an audio R signal from the input signal source 2, and symbol V ₁ is a video signal from the input signal source 2. Symbol L ₂ is an audio L signal from the input signal source 3, symbol R ₂ is an audio R signal from the input signal source 3, and symbol V ₂ is a video signal from the input signal source 3. Symbol Lo is an audio L signal output terminal, symbol Ro is an audio R signal output terminal, and symbol Vo is a video signal output terminal.
J1 is a stereo mini plug, J2-L is an RCA plug for audio L signal, J2-R is an RCA plug for audio R signal, and J2-V is an RCA plug for video signal.

  The audio signal terminals L and R and the video signal terminal V of each AV input connector group J1 (5), J2 (6) are, for example, input to the subsequent circuit after signal switching in the AV input connector group J1 (5). Resistors R14, R13, and R12 that are sufficiently small with respect to the impedances R01, R02, and R03 and sufficiently large with respect to the impedance of the input signal source 2 are inserted in series, and these resistors R14, R13, and R12 are After being connected to each signal line of the AV input connector group J2 (6), it is wired so as to hang over to the output terminals Lo, Ro, Vo.

  For example, the resistors R10, R11, R20, and R21 all have a circuit constant of 75Ω, the resistors R12, R13, and R14 all have a circuit constant of 1 kΩ, and the resistors R01, R02, and R03 all have a circuit constant of 100 kΩ.

FIG. 2 is a diagram quoted for explaining the operation principle of the input signal switching device 1 according to the first embodiment of the present invention, and only one output terminal (Lo) is shown here for the sake of simplicity. Extracted and shown.
2A shows the operation principle when signals are input from the input signal sources 2 and 3 via the AV input connector groups J1 (5) and J2 (6), and FIG. An operation principle when a signal is input from one of the input signal sources 2 and 3 via the AV input connector group J1 (5) or J2 (6) will be described.

As shown in FIG. 2 (a), AV input connector group J1 (5), J2 if the signal from the respective input signal sources 2 and 3 through the (6) is input, the input signal L ₁ is the resistance Since R14 is inserted in series, it is attenuated and is not transmitted to the output terminal Lo at the subsequent stage.
On the other hand, the signal input L ₂ which the resistor R14 is not inserted without throat attenuated N殆, is transmitted to the subsequent stage of the output terminal Lo. That is, when the signals L ₁ and L ₂ from the input signal sources 2 and 3 are input to the input signal switching device 1, the signal input L ₂ is preferentially selected and output to the output terminal Lo. (Lo≈L ₂ × ((R14 + r _g1 ) / (R14 + r _g1 + r _g2 )) ≈L ₂ ).

On the other hand, as shown in FIG. 2B, when the signal input to the input signal switching device 1 is only the signal L ₁ of the input signal source 2 of the AV input connector group J1 (5), the signal L ₁ is transmitted to the output terminal Lo in the subsequent stage with almost no attenuation (Lo = L ₁ × (R01 / (R01 + R14 + r _g1 )) ≈L ₁ ).
In the same principle, when only the signal L ₂ of the input signal source 3 of the AV input connector group J2 (6) is input, it is apparent that the input signal L ₂ is transmitted to the output terminal Lo without being attenuated. . In this way, an input signal switching operation for giving priority to one of two target signal inputs and outputting them is realized.

In FIGS. 2A and 2B, only the audio signals L ₁ and L ₂ input from the input signal sources 2 and 3 have been extracted and described. However, the audio signals R ₁ and R ₂ and the video signal are also extracted. The same input signal switching operation can be realized for the pair of V ₁ and V ₂ by inserting the resistors R13 and R12, respectively.

According to the above-described input signal switching device 1 according to the first embodiment of the present invention, the signals L ₁ and L ₂ from the respective input signal sources 2 and 3 are supplied to the AV input connector group J1 (5) and the AV input connector. When signals L ₁ and L ₂ are input by outputting to one output terminal Lo through a resistor R14 connected in parallel according to the priority order of the two systems of input terminals of group J2 (6), 1 Only the signal L ₂ from the input terminal with the higher priority (here, the AV input connector group J2 (6)) can be output to the subsequent playback circuit via the output terminals Lo. Of the _two signals L ₁ and L ₂ input at this time, the signal L ₂ on the side where the resistor R14 is not inserted is output to the output line L ₀ with little attenuation, and the resistor R14 is inserted. signal L ₁ of the side is not being sufficiently attenuated output, whereas, if the signal on the side not connected to the resistor R14 is not input, without the signal L ₁ of the insertion of the resistor R14 side is attenuated Is output.

However, the resistor R14 inserted at this time has a sufficiently large value as compared with the impedance (here, r _g1 , r _g2 ) possessed by the signal input sources 2 and 3, and the impedance R 01 possessed by the circuit in the subsequent stage. It is necessary to make the value sufficiently small in comparison. Here, for example, the resistor R14 has a circuit constant of about 1 kΩ, r _g1 and r _g2 have a circuit constant of about 1Ω, and R01 has a circuit constant of about 100 kΩ.

  As described above, according to the input signal switching device 1 according to the first embodiment of the present invention, for example, in FIG. 1, two input terminals (AV input connector group J1 (5), J2 (6)) are used. When signals are input from the respective input signal sources (1, 2), the signals of one input signal source 1 (2) are connected by resistors (R12, R13, R14) connected according to the priority order of the input terminals. Signal switching means for preferentially selecting and outputting (terminal resistors R11, R21 for matching with signal input impedances R10, R20 of each video input signal source, and resistors R12, R13, connected to the audio video signal line, R14 and a combination of input impedances R01, R02, and R03 of the subsequent circuit), thereby providing poles of resistors R11, R12, R13, and R14. Since the switching input is realized by Kano circuit components, a video signal detecting circuit disclosed in the prior art becomes unnecessary, and therefore, can provide an input signal switching device 1 at low cost.

  In addition, according to the above-described input signal switching device according to the first embodiment of the present invention, two systems of connectors having different specifications (AV input connector group J1 (5), AV input connector group J2 (6)) are connected. However, even if the same specifications are used or connectors with different specifications of the three systems are connected, the input terminals of the third system should be connected to the output of the signal switching device 1 described above. Similarly, signal switching based on the priority order is possible. Furthermore, by repeating the same connection, it is possible to perform input switching based on the priority order set for each of three or more systems of n (n is an arbitrary positive integer) input terminal (input signal source). FIG. 3 shows the circuit configuration as a modification of the first embodiment described above.

FIG. 3 shows a configuration example of the signal switching device 10 when there are n input signal sources (2, 3, 4, n). Here, n-1 (1, 1 _-2 , 1 _n-1 ) cascade connection (cascade connection) of signal switching devices having the same circuit configuration and circuit constants as the signal switching device 1 (signal switching means) described above. Thus, the signal switching device 10 is configured.
That is, Lo, Ro, and Vo that are outputs of the signal switching device 1 according to the first embodiment shown in FIG. 1 are switched together with L3, R3, and V3 that are input signal sources 4 of the third system input terminal. enter the device 1 ₂ inputs Lo that is output ', Ro', the Vo 'Ln is an input signal source n of n systems th input terminals, Rn, together with Vn, the signal switching device 1 _n-1 . Finally, one input signal Lout, Rout, Vout corresponding to the priority set for each of the n system input terminals is selectively output from the signal switching device 1 _n−1 .

In FIG. 3, symbol L ₃ is an audio L signal of the input signal source 4, symbol R ₃ is an audio R signal of the input signal source 3, and symbol V ₃ is a video signal of the input signal source 4. L _n is an audio L signal of the input signal source n, symbol R _n is an audio R signal of the input signal source n, and symbol V _n is a video signal of the input signal source n. Symbol Lout is an audio L signal output selected by the signal switching device 1 _n-1 , symbol Rout is an audio R signal selected, and symbol Vout is a video signal output selected.

Embodiment 2. FIG.
FIG. 4 is a diagram showing a circuit configuration of the input signal switching device 11 according to the second embodiment of the present invention.
As shown in FIG. 4, the input signal switching device 11 according to the second embodiment of the present invention is provided with an audio stereo input of Lch and Rch via an AV input force connector group 13 (RCA cable not including a V signal terminal). The signal source 12 is connected. The difference from the first embodiment shown in FIG. 1 resides in that two signal output terminals Lo and Ro are provided in the circuit at the subsequent stage after signal switching.

  However, here, the resistors R01 and R02 have sufficiently large resistance values with respect to the resistor R22. For example, R22 has a circuit constant of about 1 kΩ, whereas the resistors R01 and R02 have both about 100 kΩ. It shall have a circuit constant.

  FIG. 5 is a diagram cited for explaining the operation principle of the input signal switching device 11 according to the second embodiment of the present invention, and FIG. 5A shows a case where Lch and Rch signals are input. Operation Principle, FIG. 5B shows the operation principle when only one signal of Lch or Rch is input. Here, it is assumed that the resistors R01 and R02 have circuit constants of about 100 kΩ and the resistor R22 has a circuit constant of about 1 kΩ.

In FIG. 5A, when the Lch input signal L and the Rch input signal R are input from the input signal source 12 to the input signal switching device 11, the input signal L is output to the output terminal Lo. The input signal R is attenuated by the resistor R22 and is not output. On the other hand, the input signal R is output to the output terminal Ro, but the input signal L is attenuated and not output by the resistor R22 (Lo = L × ((( R22 + r _gR ) / (r _gL + R22 + r _gR )) + R × (r _gL / (r _gL + R22 + r _gR )) _≈L , Ro = R × ((R22 + r _gL ) / (r _gL + R22 + r _gR )) + L × (r _gR / (R _gL + R22 + r _gR )) _≈R ).

In FIG. 5B, when only one of the Lch input signal L and the Rch input signal R is input from the input signal source 12, the input signal L or R is applied to either of the output terminals Lo and Ro. Is output without being attenuated (Lo≈L × (R01 // (R02 + R22)) / (r _gL + (R01 // (R02 + R22))) ≈L, Ro = L × ((R22 + R02) // R01 )) / ((R22 + R02) // R01) + r _{gL ≈L} ).

  As described above, according to the input signal switching device according to the second embodiment of the present invention, when the Lch input signal L and the Rch input signal R are input from the input signal source 12, the outputs corresponding to each of them. In addition to outputting a stereo signal via the terminals Lo and Ro, when only one of the Lch input signal L and the Rch input signal R is input, the input signal is used as both output terminals. It is output via Lo and Ro.

According to the above-described input signal switching device according to the second embodiment of the present invention, a signal drawn from both ends of the resistor R22 connected between a pair of input terminals having a correlation with each other like a stereo signal is output. By providing the output terminals Lo and Ro, when a signal is input from the input signal source 12 via the pair of input terminals 13, each signal is output via the respective output terminals Lo and Ro. When only a signal is input, one of the signals input to the output terminals Lo and Ro can be output together.
Here, if a pair of input terminals are configured to be assigned to audio Lch and Rch, unlike a circuit configuration in which normal Lch and Rch inputs are directly output to the reproduction circuit, either Lch or Rch signal input is performed. Even if only one of them is connected, it is possible to output one input signal to both channels as a monaural signal. For example, one of the output terminals Lo and Ro is connected to the input signal source 12 due to poor connection or the like. Even if not, viewing via the other output terminal is possible.

_{1,1 -2, 1 n-1,} 10,11 input signal switching device, 2, 3, 4, n, 12 an input signal source, 5, 6, 13 AV input connector group, the R01, R02, R03 subsequent circuit Input impedance, impedance of _rg1 , _rg2 input signal source, R10, R11, R12, R13, R14, R20, R21, R22 resistors, Lo, Ro, Vo, Lout, Rout, Vout output terminals.

Claims (5)

Two input terminals;
When a signal is input from each input signal source through the two input terminals, the signal from one input signal source is output as one output by a resistor connected in series according to the priority order of the input terminals. A signal switching means for outputting to a circuit connected to a subsequent stage via a terminal ;
An input signal switching device comprising: The circuit constant of the resistor is
Wherein compared to each of the impedance signal input source has a sufficiently large value, the input according to claim 1, characterized in that a sufficiently small value compared to the impedance of the circuit side is connected to the subsequent stage Signal switching device. N-1 (n is an arbitrary positive integer) cascade connection of the signal switching means, and one input signal is selectively output corresponding to the priority set for each of the n input terminals. The input signal switching device according to claim 1 or 2, characterized in that The signal derived from both ends of the resistor that will be connected between a pair of input terminals and an output terminal for outputting respectively,
The signal switching means is
When signals are input from the input signal source via the pair of input terminals, each signal is output via the respective output terminals, and only one signal is input via the pair of input terminals. 2. The input signal switching device according to claim 1, wherein the one of the input signals is output to each of the output terminals. An output terminal for outputting signals drawn from both ends of a resistor connected between a pair of input terminals;
The signal switching means is
When signals are input via the pair of input terminals assigned to the left and right audio channels, a stereo signal is output via the respective output terminals, and left via the pair of input terminals. 2. The input signal switching device according to claim 1, wherein when only one signal of the channel or the right channel is input, a monaural signal is output to each of the output terminals.

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