KR920000867Y1 - Picture-in-picture automatic mute circuit - Google Patents

Abstract

No content.

Description

Picture-in-Picture Auto Mute Circuit

1 is a circuit diagram of the present invention.

2 is an input pulse waveform diagram of FIG.

* Explanation of symbols for the main parts of the drawings

10: video switching circuit 20: mute means

30: control signal generator R1-R7: resistance

Q1-Q4: Transistor D1, D2: Diode

The present invention relates to a picture in picture (PIP) function of a video tape recorder, and particularly to a tape playback picture during a picture-in-picture operation. It relates to a circuit for muting picture-in-picture subpictures when listening to the multifunction.

In general, the PIP function sets a specific area of the mother screen to the child screen and displays a screen of a different image from the mother screen on the monitor. In addition, the multi-function functions such as Picture Search, Still, and 2x.

Conventionally, when the mother screen is the tape playback screen during the PIP operation, noise occurs on the mother screen when listening to the multifunction of the tape. In order to eliminate this phenomenon, if the PIP is turned off during the playback screen of the mother screen and the PIP is turned on, this time, the sub screen always goes to the initial position, so the PIP must be shifted back to the position just before the multifunction test. There was discomfort.

Therefore, the purpose of the present invention is that when the mother screen is the tape playback screen during the PIP operation, even if the playback of the tape in multi-function, the picture can be repositioned to the position immediately before the multi-function after watching the multi-function- An in-picture auto mute circuit is provided.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. 1 is a circuit diagram of the present invention, which includes a video switch circuit 10 for receiving a window signal applied from a predetermined window signal generator for generating a window signal and forming a magnetic screen on a mother screen, and the video switching circuit 10. The muting means 20 for muting the applied window signal and the muting means 20 can be muted by controlling the muting means 20 when the PIP screen is generated during tape playback. It consists of a control signal generator 30 to control so that.

2 is an input pulse waveform diagram of FIG.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the above-described configuration and the attached first and second drawings.

First, when the PIP is turned on in the video switching circuit 10, the window signal is a switching signal for loading the child screen on the mother screen and has a state similar to that of the waveform of FIG. When the signal becomes high in synchronization with the switching signal, the mother screen becomes a tape reproducing signal, and when the mother screen becomes low, the sub picture becomes a tape reproducing signal. In addition, if the multi-function signal is high only when multi-function is performed during tape playback, and the same state as the waveform of FIG. In the signal, M denotes when the tape playback screen is the mother screen and S denotes when the broadcast signal is the mother screen. In this case, when the PIP is turned on, the window signal is applied to the video switching circuit 10 through the resistor R7 to load the child screen on the mother screen. Then when watching the multi-function of the tape when the mother screen is the tape playback screen The signal goes high and the multifunction signal goes high to apply these signals to the control signal generator 30.

When the multifunction signal applied to the control signal generator 30 becomes high, the transistor Q1 is turned on through the bias resistors R1 and R2. When the transistor Q1 is turned on, the transistor Q1 is applied to the control signal generator 30. When the signal has a high state, the transistor Q2 is turned on through the bias resistors R3 and R4. When the transistor Q2 is turned on, a low signal is generated at the collector terminal of the transistor Q2, and a low signal is applied to the muting means 20. At this time, the low signal generated at the collector terminal of the transistor Q2 turns off the transistor Q3 via the diode D1, and when the transistor Q3 is turned off, the power is supplied from the external power supply VCC. Transistor Q4 is turned on via R6) and diode D2. Eventually, since the transistor Q4 is turned on, the window signal is bypassed through the transistor Q4 and muted. The period during which the window signal is muted is shown in FIG. 2d.

Since the window signal is not applied to the video switching circuit 10 during the period, the PIP is muted because it is not switched so that the sub picture does not appear on the mother screen. However, when the multifunction ends, the multifunction signal and The signals are transitioned to the low state, and they are applied to the control signal generator 30 so that the transistors Q1 and Q2 are turned off. Therefore, a supply power supply VCC is applied to the collector terminal of the transistor Q2, which is output to the video signal controller 20 through a resistor R5. The signal input to the video signal controller 20 turns on the transistor Q3 through the diode D1 and turns off the transistor Q4.

Therefore, the window signal is released in the mute state and applied to the video switching circuit 10 again so that the normal screen is normally switched to appear in its original position in the parent screen. And When the signal goes low, the transistor Q2 is turned off regardless of the multifunction signal, and the transistor Q3 of the mute means 20 is turned on as the transistor Q2 is turned off. When the transistor Q3 is turned on, the transistor Q4 is turned off to release the window signal from the mute state. Since the unmuted window signal is applied to the video switching circuit 10, a normal PIP operation is performed. Meanwhile If the signal is low, the tape playback signal becomes the own screen. At this time, it is not necessary to mute the PIP if the multi-function does not affect the parent screen.

As described above, when the mother screen is playing the tape when watching the PIP, muting only the switching signal that carries the PIP subscreen on the mother screen without turning off the PIP when the mother screen signal is multifunctional. There is a convenient advantage in using the PIP function by bringing the sub screen.

Claims (1)

In a PIP system of a videotape recorder having a video switching circuit 10 for generating a PIP screen or a single screen by operating by a window signal applied from a predetermined window signal generator, the window signal generator is applied from the window signal generator. A video switching circuit 10 for receiving a window signal to form a child screen on the mother screen, a muting means 20 for muting the window signal applied to the video switching circuit 10, and a PIP child screen during tape playback. When the multi-function is being performed, the picture-in-picture automatic muting is characterized in that it comprises a control signal generator 30 for controlling the muting means 20 so that the muting means 20 can mute the window signal. Circuit.