JPS62130082A - Television receiver - Google Patents

Abstract

PURPOSE:To prevent the disturbance of a picture by using a free run oscillation signal of a horizontal and vertical synchronizing oscillation circuit s a video RAM access timing signal during the automatic preset or during the operation of a search function. CONSTITUTION:Under the automatic preset condition or the searching condition, a command signal of a switch off is outputted from a display controller 11 to a switch circuit 10. Thereby, in the horizontal and vertical synchronizing oscillation circuit 3, the signal of the free run frequency is generated and inputted to an address forming circuit 13 through a waveform a shaping circuit 12. Then, when the superimposing is commanded from the controller 11, character information is read from the video RAM VRAM14 in a timing synchronizing with the free run frequency, processed as an RGB signal and impressed to a mix circuit 2. In this case, a CRT4 is scanned by the free run frequency of the circuit 3, so that a clear video can be formed and the disturbance of the picture can be prevented.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a television receiver equipped with a superimpose function that allows images such as text to be superimposed on a received image and played back. be.

[Technical background and problems of the invention]

Television receivers are being supplied which reproduce text images, such as receiving channel numbers, superimposed on received images.

Figure 2 shows an example of this, where ■ is a tuner section that receives a television signal, and 2 is a mixer that mixes the video signal obtained by tuner section 1 with a superimposed video signal such as text. 3 is a horizontal/vertical synchronization oscillator circuit that generates a synchronization signal for video scanning in synchronization with the horizontal and vertical synchronization signals in the video signal supplied from the tuner section 1; 4 is a video signal from the mixer circuit 3; 3 shows a display such as a CRT that reproduces video in response to a synchronization signal from the horizontal/vertical synchronization oscillation circuit 3.

The mix circuit 2 includes a video display processor 5 (hereinafter referred to as V) that generates RGB signals as character information.
DP 5) is connected, and this VDP
5 is supplied with horizontal and vertical synchronization signals obtained from the tuner section 1 during broadcast reception.

Control data is further inputted to the VDP 5 from the display controller 6, and the VDP 5 accesses the video ram 7 based on the address data, receives and receives data such as character information, and supplies it to the mix circuit 2 as an RGB signal.

Since a conventional television receiver having a superimpose function is configured as described above, for example, during auto preset or when the search function is operating, no video signal is input from the tuner section 1, and the horizontal - Since it is no longer possible to obtain a 1υ1 signal between vertical lines, if characters such as channel display are superimposed on the display 4, the screen is distorted and the displayed characters have the disadvantage of being extremely unsightly.

[Purpose of the invention]

This invention was made in order to eliminate the drawbacks of the conventional ones described above, and at least during automatic preset generation, the timing signal for reading out the video ram is switched during the operation of the search function. The aim is to provide a television receiver.

[Summary of the invention]

In order to achieve the object described in item 1, in this invention, at least during the autopreset/node generation operation of the search function, data such as character information is read out from the video ram using free run signals of the horizontal and vertical synchronized oscillator circuits. The feature is that this read data is used to superimpose.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG.

That is, in FIG. 1, the tuner section 11 mix circuit 2, horizontal/vertical synchronized oscillation circuit 3, and display 4 are the same as those explained in FIG. 2 above, and their explanation will be omitted.

A switch circuit 10 is provided between the tuner section I and the mix circuit 2, and this switch circuit 10 prevents transmission of the video signal from the tuner section I to the mix circuit 2.
0 is controlled by the display controller 11,
At least when the television receiver is performing automatic preset generation, the switch circuit 10 is turned off while the search function is operating.

A waveform shaping circuit 12 is connected to the horizontal/vertical synchronous oscillation circuit 3, and the waveform shaping circuit 12 is connected to the horizontal/vertical synchronized oscillation circuit 3 when the switch circuit 10 is turned off.
The free run frequency of the vertical synchronization oscillation circuit 3 is given.

The horizontal and vertical synchronizing signals corresponding to the free run frequency whose waveforms have been shaped by the waveform shaping circuit 12 are applied to the address generation circuit 13.

A video ram 14 in which character information etc. to be superimposed is written is connected to this address generation circuit 13, and based on a command from the display controller 11, the video ram 14 is is accessed and specific character 19 information etc. are read out.

The character information etc. read out from the video ram 14 is applied to a character generator 15 connected to the video ram 14, and this character generator 15 generates actual screen data. The signals are input to register 16 in parallel.

An RG 13 generation circuit 17 is connected to this shift register 16, and this RGB generation circuit 17 receives a color signal from the screen data read out from the shift register 16 and converts it into an RGB signal. The voltage is configured to be applied to the circuit.

In the second configuration, when the television receiver is in the television broadcast reception mode, the switch circuit 10 is turned on and the video signal is reproduced on the display 4 via the mix circuit 2. Further, the horizontal/vertical synchronized oscillation circuit 3 causes the +IJIL display 4 to be scanned by the horizontal and vertical signals in the video signal obtained from the tuner section 1.

Further, the horizontal and vertical synchronizing signals are passed through a waveform shaping circuit 12,
The address generation circuit 13 is entered. At this time, when the display controller 11 issues a command to pause the command as required, the video RAM 14 is accessed according to the timing from the address generation circuit 13, the necessary character information is read from the RAM 14, and the character generator 15, It is processed by a shift register 16 and an RGB generation circuit 17, and text information such as a reception channel is superimposed on a display 2 through a mix circuit 2.

In an auto preset state in which the television receiver automatically presets broadcasts in the area or in a search state in which a preset channel is called, the display controller 11 sends a command signal to the switch circuit 10 to turn off the switch. is emitted.

Therefore, the horizontal/vertical synchronization oscillation circuit 3 generates a signal of the free-run frequency (adjusted approximately to the period of the normal horizontal and vertical synchronization signals) that this oscillation circuit has, and this signal is It passes through the waveform shaping circuit 12 and enters the address generation circuit 13.

When superimposition is commanded by the display controller 11, character information is read out from the timing video ram 14 synchronized with the free-run frequency by the same action as described above, and is processed as an RGB signal by the same action as described above. is applied to the mix circuit 2.

At this time, the display 4 is scanned by the free run frequency of the horizontal/vertical oscillation circuit 3, and the RGB signals read out and processed using the same free run frequency generate a clear image on the display 4 without any disturbance. .

〔Effect of the invention〕

As described above, according to the present invention, auto preset generation uses the free-run oscillation signals of the horizontal and vertical synchronized oscillation circuits as timing signals for accessing the video ram while the search function is in operation, so even if the received signal disappears, It is possible to provide a television receiver with superimposition in which images output to a display are not disturbed.

[Brief explanation of drawings]

Figure 1 is a block diagram showing one embodiment of the present invention, Figure 2 is a block diagram showing an embodiment of the present invention.
The figure is a block diagram showing an example of a conventional device. 1...Tuner section, 2...Mix circuit, 3...
Horizontal/vertical synchronous oscillation circuit, 4...Display, 10
... switch circuit, 11 ... display controller, 12 ... waveform shaping circuit, 13 ... address generation circuit, 14 ... video ram, 15 ... character generator, 16 ... shift register, 17...
RGB generation circuit.

Claims (1)

[Claims] A tuner section that receives a television signal, a mix circuit that mixes the video signal obtained by this tuner section and a superimposed video signal supplied from the outside, and a horizontal and a horizontal/vertical synchronization oscillation circuit that synchronizes with the vertical synchronization signal and generates a synchronization signal for video scanning, and receives the video signal from the mix circuit and the synchronization signal from the horizontal/vertical synchronization oscillation circuit to reproduce the video. A switch circuit is provided between the tuner section and the mix circuit to prevent transmission of the video signal from the tuner section to the mix circuit at least during auto preset generation and search function operation; A television receiver characterized in that the superimposed video signal is generated by using the free line frequency of the horizontal/vertical synchronous oscillation circuit as a synchronization signal in a state in which transmission of the video signal is blocked by the switch circuit.