JP3150019B2 - Teletext decoder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a text multiplex broadcast, in which the level of a received television signal is reduced, and conversion of text information is performed.
If the subtitle display me by the de-code error is an error has become unsightly, it relates to a teletext decoder to control so as to cancel the display.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram showing a configuration of a television receiver having a conventional teletext decoder. In the figure, reference numeral 1 denotes a television antenna for receiving broadcast radio waves in which text multiplex broadcasting is performed, and reference numeral 2 denotes a tuner for selecting broadcast radio waves of a specific channel. Reference numeral 3 denotes a television signal processing circuit, which amplifies and detects an audio intermediate frequency, an audio amplifying unit 3a for amplifying and detecting the video intermediate frequency, a video amplifying unit 3b for amplifying and detecting the video intermediate frequency, and generates horizontal / vertical synchronization signals And a luminance / color separation processing circuit 3d that separates a luminance signal and a chrominance signal from each other. Reference numeral 4 denotes a deflection circuit for deflecting the electron beam of the picture tube 5.

Reference numeral 6 denotes a channel selection processing circuit which receives a channel selection signal from a remote controller and performs control for channel selection.
a and a tuning display signal generator 6b for displaying the selected channel and the like. Reference numeral 7 denotes a text multiplex broadcast processing circuit unit, which includes a preprocessing unit 7a for extracting character information and the like multiplexed into the color television signal output from the television signal processing circuit unit 3, and a character information extracted by the preprocessing unit 7a. A decoding unit 7b for decoding display data and outputting display information; generating a RGB signal and a blanking signal corresponding to the character information in accordance with a horizontal / vertical synchronization signal supplied from the deflection circuit 4; 3 and a screen display control unit 7c that outputs the image data to the display unit 3. A tuning display signal is output from the tuning processing circuit unit 6 to the screen display control unit 7c.

Next, the operation will be described. In the receiving state of the teletext, the television signal including the text information of the teletext is transmitted from the antenna 1 via the tuner 2 to the channel of the channel selected by the remote controller. The signal is supplied to the section 3b and amplified. Then, the preprocessing unit 7a of the teletext processing circuit unit 7
In this case, character information and the like (hereinafter, referred to as a caption signal) by character multiplex broadcasting multiplexed on the scanning line 21 of the television video signal are separated. The separated caption signal is decoded by the decoding unit 7b, and the next screen display control unit 7c adjusts the RGB corresponding to the character information in accordance with the horizontal / vertical synchronization signal supplied from the deflection circuit 4 of the television receiver 5.
The signal and the blanking (BL) signal are sent to the television signal processing circuit unit 3 together with the channel selection display signal. That is, the display information is output to the luminance / color separation processing circuit unit 3d, and is output to the screen of the picture tube 5 together with the image of the television image signal.

[0005]

Since the conventional teletext decoder is constructed as described above, when the reception level of the color television signal decreases, the horizontal synchronizing signal is lost.
Table increases the error rate of the horizontal sync signal, decodes the caption signal such as character information at the decoder from
Decoding errors often occur when converting to display information, and there are problems such as incorrect characters being displayed as subtitles and the displayed subtitles being difficult to see.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a character multiplex broadcasting decoder for preventing the display of subtitles of a character multiplex broadcasting that has caused a decoding error due to a poor reception condition or has become unsightly. The purpose is to obtain.

[0007]

Teletext decoder according to the present invention According to an aspect of the mosquito that is output from the TV signal processing circuit section
Such as character information multiplexed in the color TV signal.
A pre-processing unit that separates and extracts the option signal, and the extracted
A decoder that decodes caption signals and outputs display information
And the deflection circuit that deflects the electron beam from the picture tube
The display information according to the supplied horizontal / vertical synchronization signal.
To generate an RGB signal and a blanking signal corresponding to
Screen display control for outputting to the television signal processing circuit unit
It includes a teletext processing circuit and a part, the collar
In teletext decoder for controlling the television signal processing circuit section so as to display the character information superimposed on the video screen by the over television signals, movies of the television signal processing circuit section
The horizontal sync signal reproduced in the image amplifier is
Voltage and then applied.
With Hazuki calculates and detects the error rate of the horizontal synchronizing signal of the color television signal, when the error rate of the detected the horizontal synchronizing signal is equal to or greater than a predetermined amount, not displayed in the multiplexed text information off mode Command signal
Signal to the screen display control unit and the error
An on-mode command signal for displaying the character information when the rate is equal to or less than a predetermined amount;
Error rate detection and on / off mode system output to the section
It is equipped with control means .

[0008]

In the teletext decoder according to the present invention, the error rate of the horizontal synchronizing signal, that is, the error rate is equal to the error rate.
Is monitored constantly by the detection and ON / OFF mode control means, when Erareto water <br/> horizontal sync signal I Do to reception state defective color television signal is larger than a predetermined amount,
Error rate detection and on / off mode that detects this state
The control means sends an off mode command signal to the screen display control unit.
Output, so the screen display control unit
The RGB signal and the blanking signal
It is no longer output to the road. Therefore, the display of the subtitles by the text multiplex broadcasting is turned off, and the conversion error of the character information multiplexed by the text multiplex broadcasting, that is, the display of the subtitles due to the erroneous characters due to the increase of the decoding error or the displayed subtitles While it is possible to avoid such a situation that it becomes hard to see, the color
Conversion of character information to a normal reception state over a television signal
Errors are reduced to the point where they do not interfere with the display
Therefore, only in such a state, display of subtitles by text multiplex broadcasting is performed . This prevents erroneous or unsightly subtitles from being displayed on the screen .

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a television receiver using the teletext decoder according to the present embodiment. 1, the same or corresponding parts as in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted.

In the figure, reference numeral 3e denotes an output terminal of a horizontal synchronizing signal reproduced by the video amplifier 3b of the television signal processing circuit 3. Reference numeral 10 denotes a teletext broadcasting decoder according to the present invention, which comprises a teletext processing circuit 7 and a microcomputer (CPU) 11. An input terminal 11b of the microcomputer 11 (error rate detection means, on / off mode control means) is connected to the video amplifier 3b.
The horizontal synchronization signal output from the output terminal 3e is supplied through the transistor Tr. Here, R ₁ , R ₂ , R ₃
Is a resistor, and C ₁ and C ₂ are capacitors, respectively. These values are appropriately selected so that a voltage of an appropriate value is applied to the input terminal 11b of the microcomputer 11. Then, a horizontal synchronizing signal of the video amplifying unit 3b is detected, and an error rate of the horizontal synchronizing signal is calculated and obtained. When the error rate becomes, for example, 20% or more, an off mode command is sent to the image display control unit 7c. The signal is output from the output terminal 11c of the microcomputer 11. When the error rate of the horizontal synchronizing signal becomes 20% or less, the image display controller 7
An on-mode command signal is output from the output terminal 11c of the microcomputer 11 to c. A program for realizing these series of functions is stored in a ROM of the microcomputer 11.
11a.

[0011] Next, a description will be given based on Hazuki <br/> operation flow chart shown in FIG. In the teletext decoder, first, a horizontal synchronizing signal output from an output terminal 3e of a video amplifier 3b is converted into a voltage corresponding to the horizontal synchronizing signal .
This voltage is the input terminal 11b of the microcomputer 11.
And the microcomputer 11 operates based on the input voltage.
Then, a horizontal synchronizing signal is detected (step S1). here
If the reception level of the color TV signal deteriorates ,
In this case, the reproduction of the horizontal synchronizing signal in the video amplifier 3b becomes unstable, and the voltage converted to a value corresponding thereto is applied to the input terminal 11b of the microcomputer 11 . Ma
The microcomputer 11 refers to the input voltage and
The program stored in 0M11a is executed to calculate and calculate the error rate of the horizontal synchronization signal due to the lack of the horizontal synchronization signal, and it is determined whether or not the error rate is 20% or more (step S2). And microcomputer
Motor 11, when the error rate of the horizontal sync signal is determined to be 20% or more in the step S2, with respect to the screen display control unit 7c the off mode command signal for turning off the subtitle display by teletext Output (Step S
3). Screen display control unit 7c receives the off mode command signal, turns off the display subtitles teletext that has been displayed until then.

On the other hand, the microcomputer 11 determines in step S2 that the error rate is 20% or less.
When outputs an ON mode instruction signal to turn on the subtitle display by teletext to screen display control unit 7c (step S4). Screen display control unit 7c receives the on mode command signal, to resume closed caption display by teletext broadcasting has been stopped the display before.

As a result, when the reception state of a television signal which has been conventionally teletext broadcast is deteriorated, subtitles due to teletext are difficult to read or subtitles due to incorrect text are output. In the example, such subtitles with unsightly or incorrect characters are not output.

[0014]

As described above, according to the present invention, when the reception state of the television signal being teletext broadcast is poor and the error rate of the horizontal synchronizing signal is equal to or more than a predetermined amount, the display of subtitles by teletext broadcasting is performed. Is not performed, so that it is possible to prevent the display of subtitles with characters having many errors.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a television receiver using a text multiplex broadcast decoder according to one embodiment of the present invention.

FIG. 2 is a flowchart illustrating an operation of a teletext decoder according to an embodiment of the present invention;

FIG. 3 is a block diagram illustrating a configuration of a television receiver using a conventional teletext decoder.

[Description of Signs] 3 TV signal processing circuit section 3b Video amplification section 4 Deflection circuit 5 Picture tube 7 Text multiplex broadcast processing circuit section 7a Preprocessing section 7b Decoder section 7c Screen display control section 10 Text multiplex broadcast decoder 11 Microcomputer (error rate) Detection and ON /
Off mode control means)

Claims (1)

(57) [Claims] 1. A power output from a television signal processing circuit.
Such as character information multiplexed in the color TV signal.
A pre-processing unit that separates and extracts the option signal, and the extracted
A decoder that decodes caption signals and outputs display information
And the deflection circuit that deflects the electron beam from the picture tube
The display information according to the supplied horizontal / vertical synchronization signal.
To generate an RGB signal and a blanking signal corresponding to
Screen display control for outputting to the television signal processing circuit unit
It includes a teletext processing circuit and a part, the collar
In teletext decoder for controlling the television signal processing circuit section so as to display the character information superimposed on the video screen by the over television signal, and reproduced in the video amplifying section of the television signal processing circuit section
After converting the horizontal synchronization signal to the corresponding voltage,
Been applied, the operation on the basis of this applied voltage to detect an error rate of the horizontal synchronizing signal of the color television signal
Both when the error rate of the detected the horizontal synchronizing signal is a predetermined amount or more, the multiplexed said off mode instruction signal is not performed the display of the character information screen display control unit
And output to and said error rate when the predetermined amount or less to perform the display of the character information Onmo
Output command signal to the screen display control unit
A character multiplex broadcasting decoder, comprising a port detection and on / off mode control means .