JPH04116487U - signal processing device - Google Patents

Abstract

(57) [Summary] [Purpose] To reliably prevent the return current of the video signal from flowing into the audio signal transmission path at low cost. [Configuration] Ground GND1 connected to the video signal input terminal 8 of the AV amplifier 3. is connected to the ground GND14 of the video signal power supply via the switch 20, and the ground GND2 connected to the audio signal input terminal 9 is connected to the ground GND14 of the video signal power supply, which is electrically isolated from the ground GND14 of the video signal power supply. Connected to the ground GND13 of the signal power supply. Similarly,
The ground GND3 is connected to the ground GND14 of the video signal power source via a switch 21. When using the VTR 1, by closing the switch 20 and opening the switch 21, only the ground of the video signal transmission line connected to the VTR used is connected to the ground GND14 of the video signal power supply. .

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention allows you to select any device from multiple connected devices, and AV amplifiers, AV selectors, etc. that perform signal processing of video and audio signals supplied from The present invention relates to a signal processing device.

0002

[Conventional technology]

An example of a conventional signal processing device is an AV amplifier (audio/video amplifier). FIG. 3 shows an example in which two video tape recorders are connected.

0003 Occurs at the video signal generation source 12 of the video tape recorder (hereinafter referred to as VTR) 1 The video signal to be output is outputted from the video signal output terminal 4 and sent to A via the pin code 16. The signal is supplied to the video signal input terminal 8 of the V amplifier 3. Then, the audio signal of VTR1 is The audio signal generated by the audio source 13 is output from the audio signal output terminal 5 and sent to the pin code. The signal is supplied to the audio signal input terminal 9 of the AV amplifier 3 via the cable 17 .

0004 Similarly, the video signal generated by the video signal generation source 14 of the VTR 2 is The video signal is output from the power terminal 6 and connected to the video signal input terminal of the AV amplifier 3 via the pin code 18. child 10. Then, the audio generated by the audio signal generation source 15 of the VTR 2 The signal is output from the audio signal output terminal 7 and sent to the AV amplifier via the pin code 19. The audio signal is supplied to the audio signal input terminal 11 of No. 3.

[0005] Then, in the AV amplifier 3, an input (not shown) is received from the connected VTRs 1 and 2. connected to the device (here, VTR1) selected by the signal switching circuit. Video signal and sound of VTR 1 supplied to video signal input terminal 8 and audio signal input terminal 9 The voice signals are each amplified and output to an output device (for example, a TV monitor) not shown.

[0006] In this way, in the AV amplifier 3 to which VTRs 1 and 2 are connected, Resistors R1 and R2 of each video signal transmission line in the AV amplifier 3 and the resistance of the video signal transmission line in the AV amplifier 3. The values of resistors R3 and R5 are each 75 [Ω], and the resistance of the audio signal transmission line in the AV amplifier 3 is The values of R4 and R6 are each 47 [kΩ], and the video signals output from VTRs 1 and 2 are If each voltage is 1 [Vp-p], if VTR1 is selected, the image of this VTR1 will be The characteristic impedance of the image signal transmission path is 75 [Ω], so the video signal of VTR1 The video signal supplied from the signal output terminal 4 to the video signal input terminal 8 of the AV amplifier 3 is In the figure, the return current flowing through the path GND1 → GND5 → GND9 and returning to VTR1 is 1 [V p-p]/75 [Ω] = approximately 13.3[mAp-p], and the ground input of GND1, GND5, and GND9 If the value of pedance is small, a fairly large voltage will flow. stop Similarly, when VTR2 is selected, the video signal transmission path of VTR2 is considerably affected. A return current flows at a large voltage.

[0007] The AV amplifier 3 also includes an amplification circuit (see Figure 1) for amplifying and outputting each input signal. Input signal switching circuit (not shown) that electronically switches the input signal from the device (not shown) (not shown) and a power supply circuit (not shown) that supplies power to them. The ground GND15 of the signal transmission line connected to each input terminal 8 to 11 (GN D1 to GND4) are commonly connected to each other. And if VTR1 is selected , from the video signal output terminal 4 of the VTR 1 to the video signal input terminal 8 of the AV amplifier 3. The return current of the supplied video signal is shown in the diagram from GND15→GND2→GND6→GND10. It also flows into the road. As a result, this return current is applied to the ground of the audio signal transmission path. Since the error voltage is determined by the value of the impedance, the audio signal of VTR1 The audio signal generated at the source 13 is no longer transmitted correctly to both ends of the resistor R4. This caused noise and deterioration of sound quality. In particular, the vertical synchronization signal component in the video signal When the resulting error voltage flows into the audio signal transmission path, it becomes loud enough for anyone to hear. There was a significant deterioration in sound quality.

[0008] Therefore, in the conventional AV amplifier 3, all grounds are connected to the rear panel of the housing. Each signal input terminal 8 to 11, which is the return current outlet of the AV amplifier 3, Ground each signal line with a low-impedance conductor as close as possible. By directly connecting the ground impedance (GND1, GND2) inside the AV amplifier 3, , GND3, GND4 impedance) can be ignored.

[0009]

[Problem that the idea aims to solve]

In the conventional AV amplifier 3, the ground impedance (GND) inside the AV amplifier 3 1, GND2, GND3, GND4) can be ignored, but the impedances supplied to AV amplifier 3 The return current of the video signal is not prevented from flowing into the audio signal transmission path. So, the ground impedance of pin codes 16 to 19 (GND5, GND6, GND7, GND8 impedance) and ground impedance inside VTR1 and 2 (GND9, GND10, GN D11, GND12 impedance) cannot be ignored, and return current flows. due to the transmission of error voltages caused by these ground impedances. It was not possible to prevent noise and sound quality deterioration.

0010 It also prevents the return current of the video signal transmission path from flowing into other signal transmission paths. In order to It would be fine if they were separated, but in order to do so, it is necessary to create a dedicated section for each signal transmission path inside the signal processing device. AV amplifiers, etc. that connect many devices require a separate power source, and are cost-effective. This was practically impossible because it would require too much effort.

[0011] Therefore, the present invention aims to reduce the return current of the video signal to the audio signal transmission path at low cost. The purpose is to reliably prevent the inflow of

0012

[Means to solve the problem]

As a means for achieving the above object, a plurality of first signals are supplied with the first signal. a signal input terminal, and a plurality of second signals supplied with a second signal related to the first signal. a signal input terminal, and has a configuration in which the first and second signals can be arbitrarily selected. In the processing equipment, first and second grounds electrically insulated from each other; each inserted between the first ground and the ground of the plurality of first signal input terminals. a plurality of switches connected to the second ground and the plurality of second signal inputs; The power terminal is connected directly to ground and connected only through one of the switches. The first ground and the ground of the first signal input terminal are connected. An object of the present invention is to provide a signal processing device characterized by the following.

[0013]

【Example】

An embodiment of the signal processing device of the present invention will be described with reference to the drawings.

[0014] Figure 1 shows an AV amplifier (audio/video amplifier) that is an embodiment of the present invention. This is an example in which two video tape recorders are connected. The conventional example shown in Fig. 3 and Identical components are given the same reference numerals, and their explanations will be omitted.

[0015] The AV amplifier 30 shown in the figure is a video signal to which a video signal (first signal) is supplied. The ground GND1 connected to the signal input terminal (first signal input terminal) 8 is The ground (first ground) GN of the video signal power supply (not shown) is Audio signal input terminal connected to D14 and supplied with audio signal (second signal) (Second signal input terminal) The ground GND2 connected to 9 is the video signal mentioned above. GND14 is the electrically isolated audio signal power supply ground (not shown). Connected to ground (second ground) GND13. Similarly, the video signal input terminal The ground GND3 connected to the terminal 10 is connected to the video signal voltage via the switch 21. Connected to the source ground GND14 and connected to the audio signal input terminal 11. The ground GND4 is connected to the ground GND13 of the audio signal power supply. and, When using VTR 1, close switch 20 and open switch 21. However, when using VTR2, open switch 20 and close switch 21. When closed, it is the ground for the video signal transmission line connected to the VTR being used. It is configured to be connected to the ground GND14 of the power supply for injury video signals, and the rest are as shown in Figure 3. It has the same configuration as the conventional example shown in .

[0016] In the AV amplifier 30 having such a configuration, each of the video signal outputs of the VTRs 1 and 2 is The output terminals 4 and 6 are connected to the video signal input terminals 8 and 10 of the AV amplifier 30, and the VTR The audio signal output terminals 5 and 7 of 1 and 2 are the audio signal input terminal 9 of the AV amplifier 30. , 11, and use the VTR 1. At this time, A The switch 20 of the V amplifier 30 is closed and the video signal from the VTR 1 is supplied. The video signal transmission line from the image signal input terminal 8 is connected to the ground GND14 of the video signal power supply. Also, the switch 21 is opened, and the video signal from the VTR 2 is supplied with the video signal. Is the video signal transmission path from the image signal input terminal 10 connected to the ground GND14 of the video signal power supply? It will be in a state where it is separated from the

[0017] The video signal generated by the video signal generation source 12 of the VTR 1 is output from the video signal output source 12 of the VTR 1. The signal is supplied from the power terminal 4 to the video signal input terminal 8 of the AV amplifier 30 via the pin cord 16. After being supplied with electricity, it flows through the path GND1 → GND5 → GND9 in the figure and becomes the return current of VTR1. and return to GND16 of VTR1, and also connect the ground of the video signal power supply of AV amplifier 30. It also flows into GND14. However, the ground GND14 of the video signal power supply and the audio signal Since it is electrically isolated from the ground GND13 of the video signal power supply, The return current of the video signal of VTR1 flowing into the land GND14 is the power supply for the audio signal. As a result, no sound is transmitted to the VTR1 audio signal transmission path. Only the voice signal will be transmitted. In addition, the switch 21 is in an open state. Therefore, the return current of the video signal of VTR1 is connected to the ground GND1 of the video signal power supply. 4 The audio of VTR2 is transmitted from VTR2 via the video signal transmission line (GND3→GND7→GND11). Flows from the signal transmission path (GND12 → GND8 → GND4) to the ground GND13 of the audio signal power supply, Furthermore, it also prevents the sound from flowing into the audio signal transmission path of the VTR1 and causing audio deterioration. can be done.

[0018] Also, when using the VTR 2, the switch 21 of the AV amplifier 30 is closed. and video signal transmission from the video signal input terminal 10 to which the video signal of the VTR 2 is supplied. is connected to the ground GND14 of the video signal power supply, and the switch 20 is opened. The video signal is transmitted from the video signal input terminal 8 to which the video signal of the VTR 1 is supplied. Since the transmission path is separated from the ground GND14 of the video signal power supply, the above-mentioned VTR As in case 1, the video signal of VTR2 flows only to the video signal transmission path of VTR2. , the return current of the video signal of VTR2 flows into the audio signal transmission path of VTR2. This can be prevented.

[0019] Next, a specific example of the present invention is shown in FIG. The AV amplifier 31 shown in the same figure is similar to that shown in FIG. Switches 20 and 21 are constructed of NPN transistors Q1 and Q2, respectively, and the VTR An amplifier (not shown) can be selected to process input signals from either VTR 1 or VTR 2. An input signal switching circuit 22 that switches the input to etc., and from this input signal switching circuit 22 A control signal is supplied, and the NPN transistors Q1 and Q2 are turned on and off electronically. control circuit 23, and control from the input signal switching circuit 22. The video signal transmission path can be automatically switched depending on the signal. This is what I did.

[0020] In the AV amplifier 31 shown in the figure, when using VTR1, the input switching circuit is A control signal indicating that VTR 1 has been selected via path 22 is sent to the switch control circuit. 23, this switch control circuit 23 is an NPN transistor. Supplying current to the transistor Q1 to turn on the NPN transistor Q1, and By not supplying current to the NPN transistor Q2 and turning it off, V Connect the video signal transmission line of TR1 to the ground GND14 of the video signal power supply, and The video signal transmission line shall not be connected to the ground GND14 of the video signal power supply. stop As a result, as in the case explained in FIG. Be electrically isolated from the audio signal transmission line of R1 and the video signal transmission line of VTR2. , the return current of the video signal of VTR1 flows into the audio signal transmission path of VTR1. This can prevent deterioration of sound quality.

[0021] In addition, when using VTR2, select VTR2 using the input switching circuit 22. A control signal is supplied to the switch control circuit 23, and this switch The control circuit 23 supplies current to the NPN transistor Q2 to While transistor Q2 is turned on, current is applied to NPN transistor Q1. By not supplying the video signal and turning it off, the video signal transmission line of VTR2 is turned off. Connect the video signal transmission path of VTR1 to the ground GND14 of the power supply for the video signal. It is not connected to the ground GND14.

[0022] Also in this case, the return current of the video signal of VTR2 is the same as that of the audio signal of VTR2. can be prevented from flowing into the signal transmission path.

[0023] The AV amplifiers 30 and 31 described above using FIGS. 1 and 2 are the VTRs 1 and 2. The configuration is the same when three or more devices are connected. Just do it. In other words, each video signal transmission from the video signal input terminal connected to each device A switch is provided on each path, and each video signal transmission path and video Connect the ground GND14 of the signal power supply as well as the audio signal connected to each device. Connect each audio signal transmission line from the input terminal to the ground GND13 of the audio signal power supply. , close only the switch installed on the video signal transmission path of the equipment you are using, and close the switch installed on the video signal transmission path of the equipment you are using. By leaving all switches open, the return current of the video signal of the equipment being used can be reduced. can be prevented from flowing into the audio signal transmission path.

[0024] Note that in each of the above-mentioned embodiments, video signals and audio signals are used as examples. However, it is not limited to this, and for example, a combination of a video signal and a VTR control signal may be used. Of course, it may also be a combination of an audio signal and a VTR control signal. Ru.

[0025]

[Effect of the idea]

The signal processing device of the present invention includes a plurality of first signal input terminals to which a first signal is supplied. and a plurality of second signal input terminals to which a second signal related to the first signal is supplied. In a signal processing device having a configuration in which the first and second signals can be arbitrarily selected. the first and second grounds electrically insulated from each other; a plurality of switches each inserted between the first signal input terminal of the number and the ground; The second ground and the grounds of the plurality of second signal input terminals are directly connected. At the same time, the first ground and the ground of the first signal input terminal are connected only through one switch. Since the terminals are connected to the lands, any one of the plurality of first signal input terminals the return current of the first signal supplied to the arbitrarily selected one of the first signal input terminals; flows into the first signal transmission path connected to the other first signal input terminal. This prevents signal deterioration.

[0026] It also prevents the return current of the first signal from flowing into the second signal transmission path. As a result, the quality of the second signal can be improved, e.g. When the proposal is applied to an AV amplifier or AV selector, the S/N of the audio signal will improve. , which has the effect of improving sound quality.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining one embodiment of a signal processing device of the present invention.

FIG. 2 is a diagram for explaining a specific example of the present invention.

FIG. 3 is a diagram for explaining a conventional example.

[Explanation of symbols]

1,2 Video tape recorder (VTR) 3, 30, 31 AV amplifier (signal processing device) 4, 6 Video signal output terminal 5, 7 Audio signal output terminal 8, 10 Video signal input terminal (first signal input terminal) 9, 11 Audio signal input terminal (second signal input terminal) 12, 14 Video signal generation source 13,15 Audio signal generation source 16-19 pin code 20, 21 switch 22 Input signal switching circuit 23 Switch control circuit Q1,Q2 NPN transistor (switch) R1 ~ R6 resistance GND13 Audio signal power supply ground (second ground) GND14 Video signal power supply ground (first ground)

Claims (1)

[Scope of utility model registration request] 1. A device comprising: a plurality of first signal input terminals to which a first signal is supplied; and a plurality of second signal input terminals to which a second signal related to the first signal is supplied. and the first
and a signal processing device having a configuration in which a second signal can be arbitrarily selected, first and second grounds electrically insulated from each other, and a connection between the first ground and the plurality of first signal input terminals. and a plurality of switches respectively inserted between the second ground and the ground of the plurality of second signal input terminals, and the second ground and the ground of the plurality of second signal input terminals are directly connected and only through one of the switches. A signal processing device characterized in that the first ground and the ground of the first signal input terminal are connected.