JPH0520949B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a television receiver having an outline correction function for emphasizing the outline of a displayed image and a teletext receiving function.

[Conventional technology]

In recent years, with the rapid development of electronic technology and semiconductor integration technology, there is a tendency for television receivers to have various functions added to them. These additional functions include a contour correction function and a teletext broadcast reception function.

Here, the contour correction function extracts a signal indicating the contour portion of the image from the video signal, and uses a speed modulation signal obtained by differentiating this signal to speed modulate the horizontal deflection of the electron beam in the cathode ray tube.
The display image is sharpened by emphasizing the outline of the display image. Further, the teletext multiplexing reception function extracts character signals that are multiplexed and sent during a predetermined horizontal retrace period and displays them as a character screen or superimposes them on a television screen.

[Problem that the invention seeks to solve]

However, when receiving and displaying teletext broadcasting on a television receiver that has an outline correction function, the outline correction function also acts on the character display screen, so the outline of the character screen is overemphasized. The problem is that the screen becomes difficult to view.

[Means for solving problems]

The television receiver according to the present invention receives a teletext broadcast from a signal output from a character decoder section that is built into the television receiver or connected to an external adapter through a connector. The apparatus is provided with a contour correction stop control section that determines the reception display of teletext broadcasting and stops the operation of the contour correction section.

[Effect]

In a television receiver configured in this manner, contour correction for a character screen that receives teletext is automatically stopped, making both the television screen and the character screen easy to view.

[Embodiments of the invention]

FIG. 1 is a block diagram of essential parts of an embodiment of a television receiver according to the present invention. In the figure, 1 is a tuner circuit that selects and extracts only a target television broadcast signal from signals supplied from an antenna (not shown). 2 is a video intermediate frequency amplification circuit that amplifies the output signal of the tuner circuit 1; 3 is a 21-pin type connector to which a teletext broadcast receiving adapter (not shown) is connected; and 3a is a video intermediate frequency amplification circuit that is supplied from the video intermediate frequency amplification circuit 4. 3b is a terminal to which a video signal is supplied from the teletext receiving adapter, 3c is a terminal to which a switching signal is supplied, and 3d to 3f are RGB (three primary color) signals. The terminals 3g are supplied with the TV/text screen switching signal Y _S , and 3h is the terminal supplied with the back brightness switching signal Y _M.
Reference numeral 4 denotes a video signal switching circuit which selects the video signal supplied from the video intermediate frequency amplification circuit 4 and the video signal supplied from the outside via the terminal 3b of the connector 3 according to the switching signal, and converts the video signal into a video chroma circuit. 5
supply to. Reference numeral 6 denotes an RGB signal switching circuit which selects an RGB signal supplied from the video chroma circuit 5 and an RGB signal supplied from a teletext receiving adapter (not shown) and supplies the selected RGB signal to the video output circuit 7. This RGB signal switching circuit 6 is connected to the TV signal supplied via the terminal 3g of the connector 3.
When the character screen switching signal _YS is at L level, the RGB signal supplied from the video chroma circuit 5 is selected,
When the television/text screen switching signal Y _S is at H level, the RGB signal supplied from the teletext receiving adapter is selected and output via terminals 3d, 3e, and 3f. 7 is a video output circuit connected to the RGB signal selection circuit 6, and 8 is a cathode ray tube for displaying the output of the video output circuit 7. 9 is a signal supplied from a teletext receiving adapter (not shown);
A contour correction stop control unit that determines the reception status of teletext broadcasting and outputs a correction stop signal, which is supplied from the character decoder unit built in the teletext broadcast reception adapter via terminals 3g and 3h of connector 3. It is composed of an OR gate 10 that calculates the logical sum of the television/text screen switching signal Y _S and the back brightness switching signal Y _M. Reference numeral 11 denotes an outline correction unit that enhances the outline of the displayed image, which extracts a signal indicating the outline of the image from the video signal supplied from the video signal switching circuit 4, differentiates this signal, and generates a speed modulation signal. a speed modulation signal generation circuit 12 that turns on and off the speed modulation signal output from the speed modulation signal generation circuit 12; a switch circuit 13 that turns on and off the speed modulation signal output from the speed modulation signal generation circuit 12; The speed modulation drive circuit 14 drives a speed modulation coil 15 attached to the neck portion of the tube 8. In this case, the switch circuit 13 supplies the speed modulation signal generated from the speed modulation signal generation circuit 12 to the speed modulation drive circuit 14 in the normal state, and supplies the speed modulation signal generated from the speed modulation signal generation circuit 12 to the contour correction stop control section 9.
When a correction stop signal is supplied from the speed modulation signal generation circuit 12, the speed modulation signal generated from the speed modulation signal generation circuit 12 is bypassed to ground, and the operation of the contour correction section 11 is stopped.

In the television receiver configured in this manner, the tuner circuit 1 selects and outputs a specified television broadcast signal from signals supplied from an antenna (not shown), and the video intermediate frequency amplification circuit 2 selects and outputs a specified television broadcast signal from the signals supplied from the antenna (not shown). The output television broadcast signal is amplified and supplied to the video signal switching circuit 4.
Here, in the state of receiving television broadcasting, the teletext broadcasting receiving adapter is inoperative, and therefore no switching signal is supplied. As a result, the video signal switching circuit 4 selects the video signal supplied from the video intermediate frequency amplification circuit 2 and supplies it to the video chroma circuit 5.

Furthermore, when the teletext receiving adapter (not shown) connected to the connector 3 is inactive, the TV/text screen switching signal Y _S is at the L level, so the RGB signal switching circuit 6
selects the RGB signal supplied from the video chroma circuit 5 and supplies it to the video output circuit 7. The video output circuit 7 displays the received image by driving the cathode ray tube 8 according to the RGB signal supplied from the RGB signal switching circuit 6.

On the other hand, since both the TV/text screen switching signal Y _S and the back brightness switching signal Y _M supplied from the teletext decoder section of the teletext receiving adapter (not shown) via the connector 3 are at L level, The correction stop signal outputted from the OR gate 10 constituting the contour correction stop control section 9 becomes L level, rendering the switch circuit 13 inactive.

Here, when the video signal selected by the video signal switching circuit 4 is supplied to the contour correction section 11, the speed modulation signal generation circuit 12 first detects the high frequency component of the video signal and differentiates this signal. By doing this, a limbal signal corresponding to the contour part of the image is extracted. This speed modulation signal is then supplied to the speed modulation drive circuit 14 via the switch circuit 13 which is inactive and allows the signal to pass through. When the speed modulation drive circuit 14 receives the speed modulation signal, it supplies the speed modulation coil 15 with a current corresponding to the speed modulation signal. Here, since the speed modulation coil 15 is arranged so that the magnetic field generated by it influences the horizontal deflection speed of the electron beam in the cathode ray tube 8, the horizontal deflection speed is modulated according to the speed modulation signal. become. Here, since the velocity modulation signal corresponds to the contour portion of the image, a portion of the phosphor film at the contour portion of the displayed image is increased in stimulation by the electron beam. As a result, the brightness at the outline of the displayed image increases, resulting in a sharp image.

Next, when the teletext receiving adapter (not shown) connected to the connector 3 is powered on and set to the teletext receiving mode, the teletext receiving adapter connects the video intermediate frequency amplification circuit 2 to the connector 3. The video signal received from the television broadcast supplied through the terminal 3a of the terminal 3a is taken in. Then, the teletext receiving adapter extracts the character signal that is multiplexed and sent during the horizontal retrace period of the video signal, and converts it into an RGB signal by decoding it with the built-in character signal decoder section. . The RGB signals for character display extracted in this way are supplied to the RGB signal switching circuit 6 via the terminals 3d to 3f of the connector 3. Further, the character signal decoder section built into the teletext broadcast receiving adapter sets the television/text screen switching signal Y _S to H level when sending out the RGB signal as the character display signal. As a result, RGB signal switching circuit 6
selects the RGB signal supplied via the connector 3 from the teletext receiving adapter when the television/character screen switching signal Y _S is generated, and supplies it to the video output circuit 7 . In this case, since the RGB signal supplied from the teletext receiving adapter is text information that is multiplexed and sent during the horizontal retrace period of television broadcasting, the cathode ray tube 8 is The characters will be superimposed on, for example, the lower part of the television broadcast reception screen. In addition, the text signal decoder section built into the teletext receiving adapter is
Generates a back brightness switching signal _YM corresponding to the horizontal deflection period for the area where characters are superimposed;
This back luminance switching signal _YM is supplied to the RGB signal switching circuit 6. When the RGB signal switching circuit 6 receives the back brightness switching signal _YM , it lowers the back brightness during that period to make the superimposed characters easier to see.

Here, since the OR gate 10 constituting the contour correction stop control section 9 receives the TV/character screen switching signal Y _S and the back luminance switching signal Y _M , the period when either of these signals is generated,
In other words, the correction stop signal is sent during the period in which the area for displaying received characters of teletext broadcasting is horizontally deflected. When this correction stop signal is generated, the switch circuit 13 provided in the contour correction section 11 is activated to bypass all the speed modulation signals generated from the speed modulation signal generation circuit 12 to ground. As a result, the operation of the contour correction section 11 is stopped. In other words, the outline enhancement process for the area where the characters are superimposed is stopped, thereby automatically preventing the outlines of the characters from being too emphasized and becoming difficult to see.

FIG. 2 is a circuit diagram showing a specific example of the speed modulation signal generation circuit 12 and switch circuit 13 shown in FIG. 1. In the speed modulation signal generation circuit 12,
The video signal is amplified by transistors 16 and 17. The low frequency component of this amplified video signal is grounded by the inductance 18, whereby a high frequency component signal corresponding to the outline of the displayed image is extracted. This wide-range component signal is differentiated by a differentiating circuit including a capacitor 19 and a resistor 20, and then sent out via a transistor 21 as a speed modulation signal. Further, the switch circuit 13 includes a transistor 22 connected in parallel to the inductance 18 in the speed modulation signal generation circuit 12 and turned on by the correction stop signal. Here, in normal times, since the correction stop signal is at L level, the transistor 22 is turned off and does not have any influence on the speed modulation signal generation circuit 12. On the other hand, when the correction stop signal becomes H level and the transistor 22 is turned on, all the video signals amplified by the transistor 17 in the speed modulation signal generation circuit 12 are bypassed to ground. , the speed modulation signal generation operation in the speed modulation signal generation circuit 12 is completely stopped.

FIG. 3 is a main part block diagram showing another embodiment of the television receiver according to the present invention, and the same parts as in FIG. 1 are indicated using the same symbols. The television receiver shown in Fig. 1 is configured to receive text broadcasts by externally connecting a text multiplex adapter, whereas the television receiver shown in Fig. 3 is configured to receive text broadcasts by externally connecting a text multiplex adapter. Character signal decoder section 2 extracts character signals from video signals in which signals are multiplexed and converts them into RGB signals.
3 built into a television receiver. _In this case, as in the case of the embodiment shown in _FIG . A similar operation can be obtained by controlling the operation of the section 11.

As explained above, the television receiver according to the present invention receives a teletext broadcast from a signal output from a character decoder unit built in or built into an adapter and connected via a connector in order to receive a teletext broadcast. The operation of the contour correction section is stopped by determining the reception display of the contour correction section. For this reason,
This has the effect of automatically stopping contour correction for a character screen that has received a teletext broadcast, thereby preventing deterioration in image quality due to excessive contour enhancement of the character screen.

[Brief explanation of the drawing]

FIG. 1 is a main part block diagram showing an embodiment of the television receiver according to the present invention, FIG. 2 is a circuit diagram showing a specific example of the contour correction section shown in FIG. 1, and FIG. 3 is a television receiver according to the present invention. FIG. 4 is a block diagram of main parts showing another embodiment of the digital image receiver. DESCRIPTION OF SYMBOLS 1...Tuner circuit, 2...Video intermediate amplification circuit, 3...Connector, 4...Video signal switching circuit, 5...Video chroma circuit, 6...RGB switching circuit, 7...Video output circuit, 8... ...Cathode ray tube, 9
... Contour correction stop control unit, 10 ... OR gate,
DESCRIPTION OF SYMBOLS 11... Contour correction section, 12... Speed modulation signal generation circuit, 13... Switch circuit, 14... Speed modulation drive circuit, 15... Speed modulation coil, 23... Character signal decoder.

Claims (1)

[Scope of Claims] 1. A contour correction unit that enhances the contour of a displayed image by modulating the horizontal deflection speed with a speed modulation signal obtained by differentiating a signal indicating the contour portion of the video extracted from the video signal, and a teletext broadcasting system. In a television receiver having a character signal decoder part built in or connected to an externally connected adapter and connected via a connector in order to receive text broadcasting from the signal output from the character signal decoder part. What is claimed is: 1. A television receiver comprising: a contour correction stop control section that determines reception of the contour correction section and stops the contour correction operation of the character image by the contour correction section. 2. The contour correction stop control section that determines the reception status of the teletext broadcast and stops the operation of the contour correction section controls the back of the TV/text screen switching signal output from the text signal decoder section and the area where text information is displayed. The television receiver according to claim 1, characterized in that it is constituted by an OR gate that obtains a logical sum with a back brightness switching signal that performs control to reduce the brightness of the ground. 3. The television receiver according to claim 1, wherein the contour correction section has a switch circuit that prevents the transmission of the speed modulation signal when a correction stop signal is supplied from the contour correction stop control section. .