KR19980016442A - How to automatically switch channels on television - Google Patents

Abstract

The present invention provides a method for automatically watching a video by switching a channel when there is an RF output of a video cassette recorder in a television connected to a video cassette recorder and a radio frequency (RF) line, in proportion to the strength of a received broadcast signal. Determining whether the automatic gain control signal whose voltage level is fluctuating rapidly rises above a predetermined setting range; If the automatic gain adjustment signal rises sharply above a predetermined setting range, determining whether a synchronization signal is detected while storing the currently tuned channel, switching to all RF output channels of the video cassette recorder, and tuning; Fixing the sync signal to the detected channel if the sync signal is detected and fixing to the stored current channel if the sync signal is not detected on all the RF output channels. By automatically determining and switching to the RF output channel of the video cassette recorder, it is possible to conveniently watch the video without the user's cumbersome channel manipulation.

Description

How to automatically switch channels on television

1 is a schematic block diagram of a typical television

2 is a flowchart illustrating a channel automatic switching process in a television according to the present invention.

＊ Explanation of symbols for main parts of drawing *

10: key input unit 20: microcomputer

30: tuner 40: image signal processing unit

50: voice signal processing unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic channel switching method in a television. In particular, when a user watches a video by connecting a video cassette recorder to an RF (Radio Frequency) terminal, the present invention automatically detects the channel and tunes the currently tuned channel to the RF output of the video cassette recorder. The present invention relates to an automatic channel switching method in a television for automatically switching to a channel so that a user can conveniently watch a video.

In general, a video cassette recorder modulates and outputs a reproduced video and audio signal to a predetermined channel (CH 3, CH 4), and outputs a video signal of a video cassette tape applied to the predetermined channel described above from a television connected thereto. Receive and watch the video.

On the other hand, the video cassette recorder applies a general broadcast signal from an antenna connected to the RF input terminal to the television when the power is turned off or in the television mode, and describes the signal reproduced from the video cassette tape when the power is turned on or in the video mode. Modulated to a predetermined RF output channel and output.

Therefore, when the user wants to watch the video, the user turns on the video cassette recorder and plays back the video cassette tape in the video mode to output the reproduced video signal to the predetermined RF channel.

Next, the channel currently being received on the television connected to the video cassette recorder by the RF line is switched to the RF output of the video cassette recorder described above, and the reproduced video signal is viewed.

Therefore, when a user watches a video, it is inconvenient to check which RF output channel the video cassette recorder is set to, and to switch the current channel to the set RF output channel of the video cassette recorder for viewing.

On the other hand, when receiving an RF broadcast signal from a TV, even if the size of the broadcast signal induced by the tuner changes, the output is automatically proportional to the intensity of the input video signal so as to automatically adjust the gain so that the output of the video signal is always constant. Automatic Gain Control (AGC) signal is fed back to the tuner to reduce the amplification when the intensity of the video signal is high and to increase the amplification degree when the intensity of the video signal is small so that the video signal of constant intensity is output. .

Therefore, when the video signal reproduced by the RF output of the video cassette recorder is modulated to the set channel and applied to the tuner of the television, the electric field strength of the broadcast signal from the channel of the television currently being received is weakened, so that the voltage level of the above-described AGC signal suddenly increases. Will rise.

Accordingly, it is an object of the present invention to automatically detect a video signal reproduced by a video cassette recorder connected to a television by using an AGC signal on a set RF output channel and automatically on the currently receiving channel. SUMMARY OF THE INVENTION An automatic channel switching method in a television is provided in which a video cassette recorder is switched to an RF output so that a reproduced video signal can be viewed.

The automatic channel switching method in a television according to the present invention is a method for automatically switching channels and watching a video when there is an RF output of a video cassette recorder in a television connected by an RF line with a video cassette recorder. Determining whether the automatic gain control signal whose voltage level is changed in proportion to the strength of the signal rapidly rises above a predetermined setting range; Determining whether a synchronization signal is detected while storing the currently tuned channel and switching to all RF output channels of the video cassette recorder when the automatic gain adjustment signal rises sharply above a predetermined setting range; Fixing the sync signal to the channel where the sync signal is detected and fixing to the stored current channel if the sync signal is not detected in all the RF output channels.

Other objects and various advantages of the present invention will become more apparent from the preferred embodiments of the present invention described below with reference to the accompanying drawings by those skilled in the art.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic block diagram of a general television, and as shown in the figure, a key input unit 10, a microcomputer 20, a tuner 30, a video signal processor 40, and an audio signal processor 50. It includes.

In the figure, the key input section 10 is provided with a plurality of keys including channel up / down keys for performing the operation of the television, and outputs a key signal corresponding to the user's key operation, and is usually remote A remote control capable of inputting is used to detect and output a key signal carried on an infrared carrier wave from the remote control.

Then, the overall operation of the television is controlled based on the key signal from the key input unit 10 of the microcomputer 20, and the tuning signal for channel tuning is performed based on the channel up / down key signal from the key input unit 10. Outputs (PLL (Phase Lock Loop) data), and if the applied AGC signal rises sharply above a predetermined setting range, the channel corresponding to the currently output tuning signal is stored and all the RF output channels of the video cassette recorder are scanned. Control channel switching according to the presence or absence of a synchronization signal.

In addition, the microcomputer 20 controls the video signal processor 40 and the audio signal processor 80, which will be described later, to output the broadcast signal from the tuner 30 to the monitor and the speaker.

On the other hand, the tuner 30 is connected to the RF output terminal of the video cassette recorder (not shown), and outputs a broadcast signal that is tuned and received based on the tuning signal from the microcomputer 20 and the AGC signal.

The video signal processor 40 separates and outputs an audio signal from a broadcast signal applied from the tuner 30, and outputs a video signal by separating and outputting a sync signal. The video signal is controlled according to the control of the microcomputer 20. It is processed as a displayable signal and output to the monitor.

In addition, the video signal processor 40 is proportional to the strength of the broadcast signal applied to automatically adjust the gain so that the output of the video signal is always constant even though the size of the broadcast signal induced by the antenna of the tuner 30 changes. The AGC signal is fed back to the tuner 30 and also applied to the microcomputer 20.

On the other hand, the audio signal processor 50 removes and amplifies the audio signal from the video signal processor 40 under the control of the microcomputer 20 and outputs the audio signal to the speaker.

Next, a channel automatic switching process according to a preferred embodiment of the present invention in a television including the above-described configuration unit will be described in detail with reference to the flowchart of FIG.

First, the RF output terminal of the video cassette recorder is connected to the RF input terminal of the tuner 30, and based on the channel up / down key manipulation of the key input unit 10 of the user, the microcomputer 20 performs channel tuning for the corresponding channel. The tuning signal is applied to the tuner 30 and the video signal processor 40 and the audio signal processor 50 are controlled to display and output a broadcast signal.

At this time, the microcomputer 20 periodically checks the AGC signal from the image signal processor 40 through the A / D port. As described above, the AGC signal is applied to the strength of the broadcast signal received from the tuner 30. Proportionally increases and decreases, and the increased or decreased AGC signal is fed back to the tuner 30 to maintain a constant intensity of the received broadcast signal, thereby always maintaining a constant amplitude video signal.

Therefore, the microcomputer 20 determines whether the applied AGC signal is rapidly rising above a predetermined range (step 200).

At this time, if the applied AGC signal rapidly rises above the predetermined range, the tuner 30 stores a currently tuned channel and applies a tuning signal to the tuner 30 to tune to channel 3 among the RF output channels of the video cassette recorder (step 202). ).

Next, in the tuner 30, a broadcast signal received through channel 3 is applied to the video signal processor 40, and the video signal processor 40 separates the synchronization signal and applies it to the microcomputer 20.

Accordingly, the microcomputer 20 determines whether a synchronization signal is applied (step 204), and when the synchronization signal is detected, the user recognizes that the user switches the video cassette recorder to the playback mode in order to watch the video, and changes the channel to channel 3. Keep fixing and exit.

On the other hand, if the synchronization signal is not applied in step 204, the channel 4, which is another RF output channel of the video cassette recorder, is tuned similarly to the above-described process (step 206), and it is determined whether the synchronization signal is applied (step 208). ).

At this time, if the synchronization signal is applied, the user also switches to the video cassette recorder playback mode and recognizes that the user wants to watch the video.

However, if no sync signal is applied in step 208, the microcomputer 20 recognizes that the user does not want to watch the video using a video cassette recorder and tunes back to the current channel stored in step 202. At step 210, the process ends.

As described above, according to the present invention, the video cassette recorder automatically judges the user's intention to watch the video on the television connected by the RF line as the presence or absence of a synchronization signal between the AGC signal and the RF output channel of the video cassette recorder. In order to eliminate the hassle of switching channels.

Claims (1)

A method for automatically switching channels to watch a video when there is an RF output of a video cassette recorder in a television connected to a video cassette recorder and a radio frequency (RF) line. Determining whether an automatic gain control signal whose voltage level changes in proportion to the strength of the received broadcast signal rises sharply above a predetermined setting range; If the automatic gain adjustment signal rises sharply above a predetermined setting range, determining whether a synchronization signal is detected while storing the currently tuned channel, switching to all RF output channels of the video cassette recorder, and tuning; Fixing the synchronization signal to the channel where the synchronization signal is detected and fixing to the stored current channel if the synchronization signal is not detected on all the RF output channels.