KR970004660B1 - Apparatus for video signal reversing - Google Patents

Abstract

Disclosed is a circuit for converting an image signal. The circuit comprises the first switching means(20), a synchronizing separator(60), a pulse generator(70), a blanking portion(30), an inverting amplifier(40), a mixer(50), the second switching means(100) and a controller(90). The first switching means(20) selects a signal from an output of a tuner, an external input signal and an output of deck A. The synchronizing separator(60) separates the complex synchronizing signal into the horizontal and vertical synchronizing signals. The pulse generator(70) outputs a complex blanking signal and the complex synchronizing signal according to the horizontal and vertical synchronizing signals. The blanking portion(30) outputs pure image signal according to the complex blanking signal and image signal. The inverting amplifier(40) inverts the pure image signal from the blanking portion(30) and amplifies the inverted signal. The mixer(50) outputs a complete image signal by mixing the inverted image signal and complex synchronizing signal. The second switching means(100) selectively applies the image signal from the mixer(50) or non-inverted image signal to a monitor or deck B. Thereby, the displayed image can be shown as a photographic film.

Description

Video signal switching circuit

1 is a block diagram of a video signal switching circuit according to an embodiment of the present invention.

2 (a) and (d) are output waveform diagrams of respective parts of an image signal switching circuit according to an exemplary embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal switching circuit applied to a video cassette tape recorder. In particular, a video signal is converted into a non-inverting signal and an inverting signal during dubbing using a double deck VCR or two VCRs. The present invention relates to a video signal switching circuit during dubbing.

In general, a video cassette tape recorder uses a double-deck video caste tape recorder when dubbing, or by connecting two VCRs together to dub consecutive portions of the video to copy the recordings of deck A to deck B or to copy deck B. Record the recorded content on A deck.

It is an object of the present invention to provide an image signal switching circuit that can obtain an image such as a photographic film when inverted by selectively switching an image signal when dubbing into an inverted signal and a non-inverted signal and selectively providing it from A deck to B deck.

According to an aspect of the present invention, there is provided a video signal switching method comprising: first switching means for selecting and outputting only one of an output of a tuner unit, an input signal of an external input unit, and an output signal of deck A; A sync separator for detecting a complex sync signal included in an image signal among the signals input through the first switching means and separating and outputting a horizontal sync signal and a vertical sync signal; A pulse generator for receiving the horizontal synchronizing signal and the vertical synchronizing signal separated by the synchronizing separator and outputting the composite blanking signal and the composite synchronizing signal, respectively; A blank unit which outputs only a pure video signal by inputting a composite blanking signal and a video signal of the pulse generator; An inverting amplifier for inverting the video signal of the blank part and amplifying the video signal to a predetermined level; A mixing unit for mixing the inverted image signal and the synthetic synchronous signal of the inversion amplifier unit to output a complete image signal; Second switching means for selectively switching the video signal of the mixing unit and the non-inverted video signal of the first switching means to output to the monitor or to the deck B; And a control unit for controlling the second switching means and the pulse generator.

Hereinafter, an embodiment of a video signal switching circuit according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a video signal switching circuit according to a preferred embodiment of the present invention.

Referring to FIG. 1, at least one of a dubbing means 10 including a tuner portion, an external input portion, and a deck A, and an output signal of the tuner portion, an input signal of the external input portion, and an output signal of the deck A may be provided at an output terminal of the dubbing means 10. The first switching means 20 for selecting and outputting the signal is connected to detect a composite synchronous signal included in the video signal among the signals inputted through the first switching means 20 and separates the horizontal synchronous signal and the vertical synchronous signal. The synchronous separation unit 60 is connected.

In addition, a pulse generator 70 for outputting a composite blanking signal and a composite synchronization signal, respectively, is connected to an output terminal of the synchronization separation unit 60, and extracting only a complete video signal by inputting the composite blanking signal and the composite synchronization signal. The blank section 30, the inverting amplification section 40, and the mixing section 50 are connected in series with the output terminal of the first switching means 20.

In addition, a second switching means 100 for switching and outputting an inverted video signal and a non-inverted video signal is connected to an output terminal of the mixing unit 50 and an output terminal of the first switching means 20. The deck B 110 is connected to the output terminal of the means 100.

In addition, an inverting / non-inverting MOS switching switch SW is connected to an input terminal of the control unit 90 that applies a control signal to the pulse generator 70 and the second switching means 100, and the switching switch SW is connected to one output terminal. The display unit 80 for displaying the mode operation state is connected.

The operation of the video signal switching circuit constructed as described above will be described with reference to FIG.

2 (a) to (d) are operation waveform diagrams of respective parts of the video signal switching circuit according to the preferred embodiment of the present invention.

Referring to FIG. 2A, when the TV video signal of the tuner unit, the video signal of the external input unit, or the video signal of the deck A is selected and output through the first switching means 20, the sync separation unit 60 may be applied to the video signal. The combined sync signal is detected, and the vertical sync signal and the horizontal sync signal as shown in FIGS. 2B and 2C are separated, and then output.

At this time, when the waveform of FIG. 2D is applied to the controller 90 by the mode switching switch SW connected to the controller 90, the controller 90 is connected to the second switching means 100. The waveform (e) is applied to connect the switch contact to the output terminal of the mixing section 50 to control the inversion operation.

In the inversion operation, the control unit 90 applies a control signal to the pulse generator 70, and the pulse generator 70 has a composite blank signal as shown in FIGS. And the composite synchronization signal is output.

In addition, the blank unit 30 receives the composite blank signal and outputs only the pure video signal from which the synchronization signal has been removed, as shown in FIG. 40 inverts the input signal and outputs the inverted pure video signal as shown in FIG.

In addition, the image signal output by the inverting amplifier 40 is applied to the mixing unit 50 and synthesized with the composite synchronization signal output from the pulse generator 70. The output waveform is as shown in FIG.

Therefore, the inverted video signal output from the mixing unit 90 is output to the monitor through the second switching means 100 or applied to the deck B (100).

In the non-inverting operation, the image signal of the first switching means 20 is displayed on the monitor as it is through the second switching means 100 or applied to the deck B 110.

Therefore, the video signal is divided into an inverting operation and a non-inverting operation as described above, and is supplied to the deck B. Therefore, the bright portion is darkened during the dubbing, and the dark portion is brightened to see the photographic film (negative).

Claims (3)

First switching means 20 for selecting and outputting only one of an output of a tuner, an input signal of an external input unit, and an output signal of deck A; A sync separator 60 for detecting a complex sync signal included in an image signal among the signals input through the first switching means 20 and separating the horizontal sync signal into a horizontal sync signal and outputting the sync signal; A pulse generator (70) for receiving the horizontal and vertical synchronization signals separated by the synchronization separation unit (60) and outputting the composite blanking signal and the composite synchronization signal, respectively; A blank unit 30 for outputting only the pure video signal by inputting the composite blanking signal and the video signal of the pulse generator 70; An inverting amplifier 40 for inverting and amplifying the video signal of the blank unit 30 to a predetermined level; A mixing unit 50 for mixing the inverted video signal of the inverted amplification port 40 with the synthetic synchronous signal to output a complete video signal; Second switching means (100) for selectively switching the video signal of the mixing section (50) and the non-inverting video signal of the first switching means (20) to output to the monitor or to the deck B; Image signal switching circuit, characterized in that consisting of a control unit 90 for controlling the second switching means 100 and the pulse generator 70, The video signal switching circuit according to claim 1, wherein the control unit (90) connects a mode switch to apply a control signal to the pulse generator (70) and the second switching means (100). The video signal switching circuit of claim 2, wherein the operation of all the switches is displayed on a display unit connected to a control unit output terminal.