JP2611038B2 - Television receiver - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television receiver to which a scrambled television signal is input.

2. Description of the Related Art Conventionally, for example, in pay television broadcasting in France, the starting point of a video signal in one horizontal scanning period is advanced or delayed from a specified starting point during one vertical scanning period, for example, as shown in FIG. As shown in (a), the whole video signal is shifted from the regular solid line position to the dotted line position by moving the video signal start point S 'forward by 2 μs from the specified start point S, and then the video signal in the next horizontal scanning period is shifted. The starting point S ″ is set to the specified starting point S
By shifting the entire video signal from the regular solid line position to the dotted line position with a delay of 2 μs (see FIG. 4 (c)),
A scrambled television signal is transmitted. Then, the subscriber of the pay television broadcast connects the lent decoder to the television receiver, and converts the television signal received by the decoder into a digital signal.
After scrambling, that is, the starting point S ', S "of the video signal advanced or delayed on the transmission side is returned to the specified starting point S as shown in FIG. 4 (b) and projected on the screen. Was.

Problems to be Solved by the Invention By the way, the video signal in one horizontal scanning period has a defined end point E, that is, the video signal is determined not to extend beyond the specified end point E. So
When the video signal is advanced as shown in FIG. 4 (a), its end point E 'is ahead of the specified end point E, and there is no problem.
When the video signal is delayed as shown in FIG. 4 (c), the video signal shifted after the end point E is cut and scrambled. Therefore, when the received television signal is subjected to day scrambling by a decoder and displayed on a screen, the video signal advanced by 2 μs returns to the original (prescribed) start point and end point as shown in FIG. 4 (a). As shown in FIG. 4 (c), the end point E ″ of the video signal delayed by 2 μs is 2 μs ahead of the specified end point E, and the 2 μs signal missing period T appears on the screen as a video missing portion. That is, a comb-shaped image missing portion was formed at the right end of the screen as viewed from the screen, which made the image unsightly.

The present invention has been made in view of such a point,
An object of the present invention is to provide a television receiver in which such a signal missing portion caused by scrambling does not appear on a screen as a video missing portion.

Means for Solving the Problems In order to achieve the above object, according to the present invention, scrambling is performed by advancing or delaying the start point of a video signal in one horizontal scanning period from a specified starting point during one vertical scanning period. In the television receiver to which the applied television signal is input, when the input television signal is subjected to day scrambling and projected on a screen, a configuration is provided in which means for shifting the center of horizontal deflection with respect to the screen is provided. Specifically, the means includes a horizontal deflection IC in which the center of horizontal deflection with respect to the screen is determined by a resistance value connected between the ground of the control terminal, and a resistance value connected to the control terminal. And a control transistor that varies depending on whether or not scrambling is performed.

Effect In a television receiver with such a configuration, the signal missing portion caused by scrambling is located in the overscan portion, does not appear on the screen, and has a resistance value connected to the control terminal of the horizontal deflection IC. Is variable depending on whether or not during the day scramble, so that the horizontal deflection center suitable for receiving the pay television broadcast and the normal television broadcast is set for the screen.

Embodiment Hereinafter, an embodiment of the present invention will be described with a screen.

In FIG. 1, (1) is a receiving antenna for receiving a scrambled television signal or the like as shown in FIGS. 4 (a) and (c), and (2) is a television signal received by the receiving antenna (1). And (3) a decoder connected via a 21-pin cable (5) to a 21-pin terminal (4) provided on the receiver main body (2). At the time of receiving a John broadcast, day scrambling is applied to the television signal. Therefore, the television signal received by the receiving antenna (1) is subjected to selection of a desired channel, video detection, and the like by the channel selection / video detection circuit (6) of the receiver body (2), and then to the 21-pin terminal section. (4) → Sent to the decoder (3) via the 21-pin cable (5). When receiving the pin television broadcast by the decoder (3), day scrambling is performed, and then the 21-pin cable (5) → 21
The signal is transmitted to the receiver main body (2) via the pin terminal section (4), and is subjected to signal processing such as synchronization separation, deflection, demodulation, etc. in the video processing circuit (7) of the receiver main body (2), and is transmitted to the picture tube. It is applied and projected on the screen.

When day scrambling is performed and projected on a screen, a signal missing portion (period T shown in FIG. 4 (b)) caused by scrambling is prevented from appearing as a video missing portion on the screen. The center of horizontal deflection is shifted from the screen. Specifically, a horizontal deflection IC that performs horizontal deflection included in the video processing signal (7)
(8) Connect a variable resistor (9) between the control terminal (8a) of (see FIG. 2) and the ground, and connect a control transistor (10) in parallel with the variable resistor (9). 1
1) is provided, and H is output from the decoder (3) to a specific pin terminal (4a) of the 21-pin terminal section (4) via the 21-pin cable (5) during day scrambling in the decoder (3). The control transistor (11) is
It is designed to be turned ON. Here, the horizontal deflection IC
(8) If the resistance value between the control terminal (4a) and the ground becomes small, the horizontal deflection center is shifted to the right with respect to the screen,
Conversely, when the resistance value increases, the screen is shifted to the left with respect to the screen. Normally, the horizontal deflection center is adjusted by the variable resistor (9) so as to coincide with the center of the screen.

Therefore, at the time of receiving an ordinary television broadcast without scrambling, an H-level voltage is applied from the decoder (3) to a specific pin terminal (4a) of the 21-pin terminal section (4) via the 21-pin cable (5). Since no output is made, the control transistor (11) is turned off, and only the variable resistor (9) is connected to the control terminal (8a) of the horizontal deflection IC (8). Therefore, the center of the horizontal deflection by the horizontal deflection IC (8) coincides with the center of the screen, and the center G of the horizontal amplitude of the raster (12) projected on the screen is shifted to the screen (13) as shown in FIG. ) Coincides with the center F, and the overscan portion is about 8% on both the left and right sides. next,
When receiving a scrambled pay television broadcast, day scrambling is performed by the decoder (3). At this time, the decoder (3) transmits the data via the 21-pin cable (5).
Since a high-level voltage is output to a specific pin terminal (4a) of the 21-pin terminal section (4), the control transistor (11) is turned on.
Thus, the variable resistance (9) and the resistance (10) are connected in parallel to the control terminal (8a) of the horizontal deflection IC (8). For this reason, the resistance value connected between the control terminal (8a) of the horizontal deflection IC (8) and the ground becomes smaller than that during normal television broadcast reception, and the center of horizontal deflection by the horizontal deflection IC (8) is reduced. Is shifted to the right with respect to the screen, and the center of the horizontal amplitude of the raster (12) projected on the screen is adjusted so that the overscan portion is about 4% on the left and about 12% on the right (FIG. 3 (b)). ) Is shifted rightward with respect to the center F of the screen (13). As a result, the comb-shaped image missing portion caused by scrambling at the right end of the raster (12) is located at the overscan portion and does not appear on the screen.

Note that the ratio of the left and right sides of the overscan portion when receiving pay television broadcast is determined by the value of the resistor (10).

According to the television receiver of the present invention as described above,
When receiving the scrambled television signal and projecting it on the screen, the center of the horizontal deflection is shifted using the horizontal deflection IC so that the signal missing portion caused by the scramble is located in the overscan portion. Therefore, the signal missing portion does not appear as a video missing portion on the screen, and the image quality can be significantly improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a decoder and a receiver main body used in the present invention, FIG. 2 is a diagram showing a concrete circuit configuration example for realizing the present invention, and FIG. FIG. 4 is a diagram showing the relationship, and FIG. 4 is a diagram showing a video signal in one horizontal scanning period to which scrambling and day scrambling have been applied, respectively. (2)… Receiver body, (3)… Decoder, (8)… Horizontal deflection IC, (8a)… Control terminal, (11)… Control transistor.

Claims (2)

(57) [Claims] 1. A television receiver to which a scrambled television signal is inputted by advancing or delaying a start point of a video signal in one horizontal scan period from a prescribed start point during one vertical scan period. 2. A television receiver according to claim 1, further comprising means for shifting the center of horizontal deflection with respect to the screen when the input television signal is subjected to day scrambling and projected on the screen. 2. The horizontal deflection IC wherein the center of horizontal deflection with respect to the screen is determined by a resistance value connected between the control terminal and ground, and a resistance value connected to the control terminal is descrambled. The television receiver according to claim 1, further comprising a control transistor that varies depending on whether or not the time has elapsed.