JPS6266788A - Flicker eliminating circuit in television receiver - Google Patents

Abstract

PURPOSE:To eliminate flicker of a picture that occurs at the position of an idle channel when switching channel and to display in an elementary color by separing a synchronizing signal in a video signal and making on and off an elementary color generating circuit. CONSTITUTION:As synchronizing signals are contained in the video signal when selecting channel during broadcasting, synchronizing signals (preferably vertical synchronizing signals) are separated and detected by a synchronizing signal separating circuit 2. These are amplified by an amplifier circuit 3 and turns a switching circuit 4 on or off. Then, elementary color generating circuits 9, 10 are controlled to an inactive state, and a normal image is projected. As no synchronizing signal exists when idle channel is selected, the synchronizing signal is not detected from the synchronizing signal separating circuit 2, and the switching circuit 4 is turned on or off. Then, the circuits 9, 10 operate and the picture is displayed in the elementary color.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a flicker erasing circuit for erasing screen flickering caused by noise when selecting an empty channel on a television receiver and displaying the screen in a single color. It is.

``Prior Technology J: When a television receiver selects an idle channel, an extremely disturbing flicker occurs across the screen, but conventionally there was no circuit to eliminate this.

``Problem that the invention aims to solve'' 2 This flickering causes an unpleasant feeling every time you change channels, so when selecting an empty channel, immediately erase it, pass through the empty channel, and select the channel that is currently broadcasting. What was desired was something that would return the screen to normal again.

"Means for Solving the Problems" The present invention has been made to solve the above-mentioned problems, and includes a synchronization signal separating circuit in a video signal and a circuit for amplifying this separated synchronization signal. It consists of a switch circuit that turns on and off depending on the presence or absence of an output from this amplifier circuit, and a single color generation circuit that is controlled by this switch circuit.

"Operation" When a channel being broadcast is selected, the video signal contains a synchronization signal, so the synchronization signal (preferably the vertical synchronization signal) is separated and detected by the synchronization signal separation circuit.
This is amplified by an amplifier circuit and turns the switch circuit on or off. Then, the single color generating circuit is controlled to be inactive and a normal image is displayed on the screen.

When an empty channel is selected, there is no synchronization signal, so no synchronization signal is detected by the synchronization signal separation circuit.
The switch circuit turns off or on. Then, the single color generation circuit operates and the screen is displayed in a single color.

"Example" An embodiment of the present invention will be described below with reference to the drawings.

(1) is a video signal input terminal, this input terminal (1) is coupled to a synchronization signal separation circuit (2) for separating a vertical synchronization signal, and an amplifier circuit (3) for amplifying the separated synchronization signal. It is coupled to a switch circuit (4) which outputs an output when the synchronization signal disappears. This switch circuit (4)
is the transistor (5) (6) and the collector resistance (
7) 1st consisting of (8). Second single color generation circuit (9)
(10). Of these, the first single color generating circuit (9) connects the base resistor (12) of the chroma matrix transistor (11) via the collector resistor (7).
) and the base resistor (14) of the video matrix transistor (13). In addition, (15) (1
6) are the input and output terminals of the chroma signal, and (17)
(18) are an input terminal and an output terminal for video signals.

The second single color generating circuit (10) has a collector resistor (
8) between the emitter resistors (21) and (22) of a transistor (20) of a primary color output circuit (19) that outputs one of the three primary colors R, G, and B.

The base of the transistor (20) is connected to a color difference signal input terminal (23), and the emitter is connected to a resistor (24) (
25), a luminance signal input terminal (27) is coupled via a capacitor (26), and a primary color output terminal (28) is connected to the collector.
) are combined.

In order not only to display a single color on the screen but also to eliminate the noise, a transistor (29), a diode (30),
An audio mute circuit (32) consisting of a resistor (31) is coupled. The resistor (35) in the volume control line runs from the volume control terminal (33) to the audio output terminal (38) via the volume control transistor (36) and the attenuator (37).
34) Connect the audio mute circuit (3) to the connection point of (35).
2) are combined. (39) is an audio signal input terminal.

In the above configuration, while a video signal is being sent to the video signal input terminal (1), the vertical synchronization signal is separated and detected by the synchronization signal separation circuit (2), and this is detected by the amplifier circuit (3). The transistors (5) (6) (29) of the first and second single color generation circuits (9) (10) and the audio mute circuit (32) are amplified and turn off the switch circuit (4).
) is off. Therefore, the first single color generation circuit (9
), the color signal at the chroma input terminal (15) is output to the output terminal (16) via the transistor (11), and the video signal at the video input terminal (17) is output to the output terminal (18) via the transistor (13). Output. Further, the second single color generating circuit (10) also outputs a single primary color to the output terminal (29) without being distorted. In addition, the volume control terminal (
The volume control signal input to the volume control transistor (36) and the attenuator (
37), and the audio signal is sent to the output terminal (38) as it is.
Sent to nine.

Next, when selecting an empty channel or passing through a channel with no video signal, there is no video signal at the video No. 43 input terminal (1), so there is no output from the synchronization signal separation circuit (2), and the amplifier circuit ( There is no output for 3).

Therefore, the switch circuit (4) is turned on and the output is turned on. The output of this switch circuit (4) causes the first and second
Transistors (5) (of single color generation circuits (9) (10))
6) and the transistor (29) of the audio mute circuit (32)
) turns on. When the transistor (5) of the first single color generation circuit (9) is turned on, the chroma matrix transistor (11) and the video matrix transistor (13) are turned on.
) is lowered and becomes a black level signal. Also the second
When the transistor (6) of the single color generation circuit (10) is turned on, the emitter potential of the transistor (20) of the primary color output circuit (19) decreases, but the base potential does not change.
The base-emitter voltage increases, and the collector potential decreases accordingly. Therefore, the primary colors from the input terminal (23) are emphasized and output to the output terminal (28). However, the screen is R, G, and B that are present at the output terminal (28).
Displayed in one of the primary colors.

Further, when the transistor (29) of the audio mute circuit (32) is turned on, the volume control terminal (33)
The noise signal input to the audio mute circuit (32) passes through the diode (30) and the transistor (29) and is released to the ground, and is then connected to the transistor (36) and attenuator (3).
7) and the noise is eliminated.

In the embodiment, in order to display the screen in a single color, a first single color generating circuit (9) and a second single color generating circuit (10) are used.
Both are provided, but only the first single color generating circuit (9) is provided,
The screen may simply be displayed in black.

In the embodiment described above, in addition to eliminating screen flickering, noise cancellation is also performed at the same time, but it is also possible to eliminate only screen flickering.

In the above embodiment, the vertical synchronization signal is separated and used in the synchronization signal separation circuit (2), but it is also possible to separate and use the horizontal synchronization signal (ff signal) as long as it can be distinguished from a noise signal.

In the embodiment described above, the volume control signal is grounded by the audio mute circuit (32), but the present invention is not limited to this. The operation may be stopped.

[Effects of the Invention] Since the present invention is configured as described above, the flickering that occurs on the screen at the position of an empty channel when switching channels is eliminated and the screen is displayed in a single color, thereby eliminating discomfort. Furthermore, if one of the primary colors of R, G, and B is emphasized, not only will it not be mistaken for a malfunction in the receiver, but it will also give a more pleasant feeling. The exposed circuit configuration is also simple and inexpensive.

[Brief explanation of drawings]

The figure is an electrical circuit diagram showing one embodiment of the flicker erasing circuit according to the present invention. (1)...Video signal input terminal, (2)...Sync signal separation circuit. (3)...Amplifier circuit, (4)...Switch circuit, (
9)...first single color generation circuit, (10)...second
Single color generation circuit. (11)...Chroma matrix transistor,
(13)...transistor for video matrix, (
19)...Primary color output circuit.

Claims (3)

[Claims] (1) A synchronization signal separation circuit in the video signal, a circuit that amplifies this separated synchronization signal, a switch circuit that turns on and off depending on the presence or absence of the output of this amplification circuit, and a single color controlled by this switch circuit. 1. A flicker elimination circuit for a television receiver, comprising a generation circuit. (2) The single color generating circuit comprises a first single color generating circuit for lowering the bias of the color signal and the video signal to produce a black screen.Flicker elimination in the television receiver according to claim 1 circuit. (3) The single color generation circuit consists of a first single color generation circuit that lowers the bias of the color signal and video signal to create a black screen, and a second single color generation circuit that emphasizes the primary color output circuit to create a primary color screen. A flicker elimination circuit for a television receiver according to claim 1, comprising a single color generation circuit.