JP2944385B2 - Television receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television receiver for displaying an input video signal on a screen having a horizontally long aspect ratio different from this aspect ratio.

[0002]

2. Description of the Related Art Hitherto, in a video display device such as a television receiver, the ratio of the length to the width of the screen is usually 3: 4 in the broadcasting standard such as NTSC.

[0003] In recent years, however, television broadcasts have tended to have larger screens in order to feel a sense of presence and power. Therefore, in a cathode ray tube or the like for displaying a television signal, a horizontally long screen having an aspect ratio of 9:16 has penetrated in order to cope with the enlargement of the screen.

[0004] However, television broadcasts are not all broadcasts having an aspect ratio of 9:16, but are still broadcasts having a 3: 4 aspect ratio.

Therefore, it is necessary to display a plurality of images having different aspect ratios even in a cathode ray tube having a single aspect ratio.

Therefore, in order to make use of the sense of presence and power,
There is a method (display mode) of displaying an image using a cathode ray tube having an aspect ratio of 16. An image having an aspect ratio of 3: 4 has a mode (hereinafter referred to as a normal mode) in which a 3: 4 image is displayed as it is as shown in FIG.

When a 3: 4 video signal is displayed on a 3: 4 CRT, the video portion of the video signal from the horizontal synchronizing signal differs due to variations in the transmission of the video signal. A few percent (about 8%) of the signal extends outside the area that can be displayed on a CRT, up, down, left, and right to display a video signal. This is what is called overscan.

However, when a 3: 4 screen is displayed on a 9:16 CRT in a normal mode, left and right overscanned video signals appear in the display area of the CRT, and the left and right of the image are not aligned due to the variation. Would be. That is, horizontal scanning is not performed on the entire 9:16 screen, and horizontal scanning is performed on the central region including the hatched region in FIG.

Therefore, in the conventional example, the circuit shown in FIG. 4 is used to blank out the overscan in the shaded area shown in FIG.

In FIG. 1, reference numeral 1 denotes a video signal processing circuit for outputting an input video signal as an RGB signal. 2 is an RGB signal for displaying an RGB signal on the CRT 3
Drive circuit. Reference numeral 3 denotes an input of an H pulse based on a horizontal synchronizing signal from the video processing circuit 1, and the generation of a blanking pulse for forcibly lowering the video signal to a predetermined level (substantially the ground level in this case) with the H pulse. Blanking pulse generation circuit.

Reference numerals 4R, 4G, and 4B denote transistors that set the RGB signals output from the video signal processing circuit 1 to a substantially ground potential by a blanking pulse.

The video processing circuit 1 is constituted by a block diagram as shown in FIG.
DA8360). Y / C separation circuit 11 for separating a video signal input to input terminal 1a into a luminance signal and a chrominance signal
, The chrominance signal is input to the color processing circuit 12 and the luminance signal is input to the luminance processing circuit 13 and the synchronization separation circuit 17. The signals processed by the color processing circuit 12 and the luminance processing circuit 13 are converted into RGB signals by an RGB processing circuit 14.

Also used for on-screen purposes, the RGB signal inputted from outside and the RGB signal are switched by an RGB switching circuit 15 by a switching signal Ys. That is, the RGB signal is input from the input terminals 1c, 1d, and 1e to perform the on-screen display, and at the same time, the switching signal Ys is input to the input terminal 1b.
Selects the on-screen RGB signal from the RGB signal of the video signal, and selects and outputs the RGB signal of the video signal when there is no on-screen display.

The selected RGB signal is supplied to terminal 1
f, the luminance level and the contrast ratio are adjusted by the luminance adjusting means 5a (for example, a variable resistor) and the contrast adjusting means 5b connected to the terminal 1g, and the terminals 1x, 1y, 1
output from z.

On the other hand, in the horizontal pulse (H pulse) generation circuit, the synchronization signal separated by the synchronization separation circuit 17 generates an H pulse which is at the H level only during the horizontal synchronization signal period.
The H pulse is output from the terminal 1h.

The H pulse generates a horizontal blanking pulse in a horizontal blanking generation circuit shown in FIG. FIG. 7 is a time chart of occurrence of horizontal blanking.

In these figures, a horizontal pulse a input to pin 2 obtains pulse b via a first three-input AND circuit and a first T-flip-flop. This pulse b
Becomes H level from the falling of the horizontal pulse, and 13,
The H level is maintained during the time constant τ1 determined by the time constant circuit including the resistor and the capacitor connected to the 14th pin, and the remaining period B1 of the horizontal scanning period H and the H pulse period HP are at the L level.

The generated pulse b is output from pin 13 and re-input to pin 9. Then, the pulse b obtains a pulse c via the second three-input AND circuit and the second T-flip-flop. This pulse c becomes L level from the falling edge of the pulse b, and keeps L level during a time constant τ2 determined by a time constant circuit composed of a resistor and a capacitor connected to pins 6 and 7; The remaining period is at the H level. Here, the time constant τ2 includes a period B2 having substantially the same length as the period B1, a period B1 and a horizontal pulse period HP.

Then, the signal is output from the 12th pin and inverted by a transistor to obtain a pulse d. This pulse d is output as a horizontal blanking pulse via a diode for preventing backflow.

Therefore, a blanking pulse wider than the horizontal pulse can be generated.

Next, the operation will be described with reference to FIG. In the video processing circuit 1, the input video signal is adjusted to a level R adjusted by the luminance adjustment unit 5 a and the contrast adjustment unit 5 b.
It is output as a GB signal.

Then, as described above, the 9:16 CRT
In order to prevent the left and right overscanned video signals from appearing in the display area of the CRT when the 3: 4 image is displayed in the normal mode, the left and right sides of the image are prevented from being aligned due to the variation. By the blanking signal from the blanking pulse generating circuit 3, the RGB signals are blanked at the same horizontal position, and the left and right image areas can be aligned as shown by the hatched portion in FIG. As a result, the left and right sides of the image do not vary.

[0023]

SUMMARY OF THE INVENTION However, RGB
A circuit that influences a blanking signal is required for each signal path, and at least three identical circuits are required. Therefore, various adjustments and settings have to be performed in each circuit, which is troublesome.

On the other hand, by blanking the input video signal, it is possible to blank even with one path. However, the blanked level is a pedestal level, and since the level is biased by the luminance adjusting means, even if the input video signal is blanked, the horizontal blanking area displayed on the CRT (the hatched area in FIG. 3) The level of the (area) does not become a perfect black level, and a difference in luminance level from the non-image area occurs, which may make it difficult to see.

[0025]

According to the present invention, there is provided a television receiver for displaying an input first video signal on a screen having an aspect ratio different from the aspect ratio of the first video signal. A signal processing unit for selectively outputting a video signal by a switching signal for switching a second video signal different from the first video signal to the first video signal and displaying the same on the same screen, and displaying an output video signal of the signal processing unit Display means for generating, a horizontal pseudo signal generation means for generating a horizontal pseudo signal from a horizontal synchronization signal of the first video signal, and the display means displaying at least a level of the output video signal during a period in which the horizontal pseudo signal is obtained. It is an object of the present invention to provide a television receiver comprising a video invalidating means for setting a cutoff level which is a level not to perform.

The input first video signal is converted to the first video signal.
In a television receiver for displaying on a screen having an aspect ratio different from that of a video signal, switching for switching a second video signal different from the first video signal to the first video signal and displaying the same on the same screen. Signal processing means for selectively outputting a video signal according to a signal, display means for displaying an output video signal of the signal processing means, and a horizontal pseudo signal for generating a horizontal pseudo signal from a horizontal synchronization signal of the first video signal Generating means, brightness adjusting means connected to the signal processing means for controlling the brightness of the selected output video signal, and brightness adjustment invalidating the output of the brightness adjusting means by the horizontal pseudo signal Means for adding the horizontal pseudo signal to the switching signal, and at least the level of the output video signal is obtained during the period in which the horizontal pseudo signal is obtained. The it is to provide a television receiver, characterized in that the cut-off level is the level that the display means does not display.

[0027]

According to the present invention, the horizontal blanking signal is superimposed on the on-screen switching signal, and the output of the adjusting means for adjusting the brightness is invalidated.

[0028]

FIG. 1 is a circuit block diagram showing an embodiment of the present invention. The same portions as those in the conventional example are denoted by the same reference numerals, and description thereof will be omitted.

Reference numeral 6 denotes a diode which conducts at the H level of the horizontal blanking signal. Reference numeral 7 denotes a transistor to which a horizontal blanking signal is input via a resistor 8. The base of this transistor 7 is connected to a horizontal blanking signal by a resistor 8
This emitter is grounded, and is used for adjusting the luminance of the video processing circuit 1 so that the DC level of the luminance adjusting means connected to the collector is invalidated when the horizontal blanking signal is at the H level. Set the terminal to almost zero potential.

Next, the present invention will be described with reference to FIG. As shown in FIG. 2, the input video signal a is switched by the video processing circuit 1 to an RGB signal such as an on-screen signal by a signal b indicating the switching signal Ys to obtain an output video signal. The circuit 1 separates the horizontal synchronizing signal and obtains the H pulse c.
The horizontal blanking pulse d is obtained by the horizontal blanking pulse generation circuit 4 based on the H pulse c. The horizontal blanking pulse d includes a front porch portion and a back porch portion before and after the horizontal synchronization signal, and is a wider pulse.

The horizontal blanking pulse d is added to the switching signal Ys via the diode 6,
A signal e is created and input to the video processing circuit 1 as a switching signal Ys'.

On the other hand, the transistor 7 to which the horizontal blanking pulse d is input is connected to the output of the brightness adjusting means 5a. When the horizontal blanking pulse is at the H level, the DC adjusted by the brightness adjusting means 5a is used. The level (which is a luminance level on the screen) is set to substantially zero level.

Therefore, when the horizontal blanking pulse d is input as shown in FIG. 7F, the DC level adjusted by the brightness adjusting means 5a is invalidated, and the video signal is output to the CRT.
The B0 level, which is a luminance level that cannot be displayed in 3 or a luminance level lower than that (that is, a cutoff level or less). In addition, the video signal becomes the B1 level, which is the lowest luminance level of the luminance level currently adjusted by the luminance adjusting means 5a, by the signal e which is the switching signal Ys'.

That is, since the lowest luminance level is made invalid by the horizontal blanking pulse and the B0 level is equal to or lower than the cut-off level, the horizontal blanking pulse is switched to the lowest luminance level by the switching signal Ys'. It becomes a certain B0 level.

During the period during which the RGB signals such as on-screen signals are inputted, the DC level set by the luminance adjusting means 5a is maintained, and the switching signal Ys' changes to the B1 level which is the lowest luminance level. Here, the display such as the on-screen is not described, but any of the RGB signals or a plurality of
It is displayed in the color set by the B signal, and is displayed at the highest luminance level as indicated by the hatched portion in FIG.

[0036]

According to the present invention, a CR having an aspect ratio of 9:16 is used.
When displaying a video signal having an aspect ratio of 3: 4 on a television receiver having a T, horizontal blanking for preventing left and right variations of an image is not applied to each of the RGB outputs. At the same time, the circuit for each of the RGB signals becomes unnecessary, and the circuit configuration is simple and the adjustment is easy.

Further, by controlling the luminance adjustment at the same time during the horizontal blanking period, even when the luminance adjustment is DC biased, the floating of black in the horizontal blanking portion is eliminated.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram of an embodiment of the present invention.

FIG. 2 is a waveform diagram of an embodiment of the present invention.

FIG. 3 is a diagram showing a CRT display screen.

FIG. 4 is a circuit block diagram of a conventional example.

FIG. 5 is a diagram showing a video processing circuit.

FIG. 6 is a diagram showing a horizontal blanking generation circuit.

FIG. 7 is a diagram showing generation of a horizontal blanking pulse.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Video processing circuit 2 RGB drive circuit 3 CRT 4 Horizontal blanking generation circuit 5a Brightness adjustment means (variable resistance) 5b Contrast adjustment means (variable resistance) 6 Diode 7 Transistor 8 Resistance

Claims (1)

(57) [Claims] 1. A television receiver for displaying an input first video signal on a screen having an aspect ratio different from the aspect ratio of the first video signal, wherein a second video signal different from the first video signal is displayed. A signal processing unit for selectively outputting a video signal by a switching signal for switching to the first video signal and displaying the same on the same screen; a display unit for displaying an output video signal of the signal processing unit; Horizontal pseudo signal generation means for generating a horizontal pseudo signal from a horizontal synchronization signal of a video signal; brightness adjustment means connected to the signal processing means for controlling the brightness of a selected output video signal; and the horizontal pseudo signal A brightness adjustment invalidating means for invalidating an output of the brightness adjusting means, and a horizontal pseudo adding means for adding the horizontal pseudo signal to the switching signal. Television period obtained the horizontal pseudo signal, characterized in that the cut-off level is a level at which the level of the output video signal is the display means does not display.