JPH07115652A - Television receiver - Google Patents

Abstract

PURPOSE:To unnecessitate the respective circuits for RGB signals, to simplify circuit configuration and to facilitate adjustment by applying no horizontal blanking to respective RGB outputs at the time of displaying video signals whose aspect ratio is 3:4 in a receiver provided with a CRT whose aspect ratio is 9:16. CONSTITUTION:The inputted video signals (a) are switched with the RGB signals of on-screen or the like by signals (b) indicated in switching signals Ys in a video processing circuit 1 and output video signals are obtained. Also, the circuit 1 separates horizontal synchronizing signals to obtain H pulses (c). In a horizontal blanking pulse generation circuit 4, horizontal blanking pulses (d) are obtained by the pulses (c). The pulses (d) are provided with a front porch part and a back porch part present in front and back of the horizontal synchronizing signals and are the wider pulses. The pulses (d) are added to the switching signals Ys through a diode 6, prepare the signals (d) and are inputted to the processing circuit 1 as the switching signals Ys'. In the meantime, a transistor turns a DC level adjusted in a brightness adjustment means 5a to an approximately zero level when the pulses (d) are H.

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 landscape aspect ratio different from this aspect ratio.

[0002]

2. Description of the Related Art Conventionally, in a video display device such as a television receiver, the aspect ratio of the screen is generally 3: 4 in view of broadcasting plans such as NTSC.

However, in recent years, there has been an increasing tendency for television broadcasting to have a larger screen in order to feel a sense of reality and power. Therefore, in a cathode ray tube or the like which displays a television signal, a horizontally long screen having an aspect ratio of 9:16 has permeated in order to cope with the large screen.

However, not all television broadcasts have an aspect ratio of 9:16, but there are still 3: 4 broadcasts.

Therefore, it is necessary to display a plurality of images having different aspect ratios even on a CRT having a single aspect ratio.

Therefore, in order to make the most of the sense of presence and the force, 9:
There is a method (display mode) for displaying an image using a CRT having an aspect ratio of 16. As for an image having an aspect ratio of 3: 4, there is a mode in which an image of 3: 4 is displayed as it is (hereinafter referred to as a normal mode), as shown in FIG.

When a 3: 4 video signal is displayed on a 3: 4 CRT, the video portion from the horizontal synchronizing signal of the video signal is different due to variations in transmission on the side transmitting the video signal. A few percent (about 8%) of the signal is displayed outside the area where it can be displayed on the CRT, vertically and horizontally to display the video signal. This is so-called overscan.

However, when a 3: 4 screen is displayed in the normal mode on a 9:16 CRT, 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. Will be lost. That is, horizontal scanning is not performed on the entire screen of 9:16, and horizontal scanning is performed on the central area including the hatched area in FIG.

Therefore, in the conventional example, the circuit as shown in FIG. 4 blanks the overscan in the shaded area shown in FIG.

In this figure, reference numeral 1 is a video signal processing circuit for outputting an input video signal as an RGB signal. 2 is RGB for displaying RGB signals on the CRT 3
It is a drive circuit. Further, 3 receives the H pulse by the horizontal synchronizing signal from the video processing circuit 1 and generates a blanking pulse for forcibly lowering the video signal to a predetermined level (here, substantially the ground level) with the H pulse. It is a horizontal blanking pulse generation circuit for.

Reference numerals 4R, 4G, and 4B are transistors that bring 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 constructed by a block diagram as shown in FIG. 5. For example, a Philips IC (T
DA8360). The Y / C separation circuit 11 that separates the video signal input to the input terminal 1a into a luminance signal and a chrominance signal.
The color signal is input to the color processing circuit 12, and the luminance signal is input to the luminance processing circuit 13 and the sync separation circuit 17 via the. The signals processed by the color processing circuit 12 and the brightness processing circuit 13 are converted into RGB signals by the RGB processing circuit 14.

Also used for on-screen, the RGB signal input from the outside and the RGB signal are switched by the RGB switching circuit 15 by the 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 when there is no on-screen display, selects and outputs the RGB signal of the video signal.

Then, the RGB signal obtained by selection is the terminal 1
f, the brightness level and the contrast ratio are adjusted by the brightness adjusting means 5a (for example, variable resistance) and the contrast adjusting means 5b connected to the terminals 1g, and the terminals 1x, 1y, 1
It is output from z.

On the other hand, in the horizontal pulse (H pulse) generating circuit, the synchronizing signal separated by the synchronous separating circuit 17 forms an H pulse which is at the H level only during the horizontal synchronizing signal period.
The H pulse is output from the terminal 1h.

The H pulse is generated by the horizontal blanking generation circuit shown in FIG. FIG. 7 is a time chart diagram of horizontal blanking occurrence.

In these figures, the horizontal pulse a input to the 2nd pin obtains the pulse b through the first 3-input AND circuit and the first T-flip-flop. This pulse b
Becomes H level from the fall of the horizontal pulse, 13,
The H level is maintained during the time constant τ1 determined by the time constant circuit composed of 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 the 13th pin and input again to the 9th pin. Then, this pulse b obtains a pulse c via the second 3-input AND circuit and the second T-flip-flop. This pulse c becomes L level from the trailing edge of the pulse b, keeps L level during the time constant τ2 determined by the time constant circuit composed of the resistor and capacitor connected to pins 6 and 7, and keeps the L level during the horizontal scanning period H. The H level is maintained for the rest of the period. Here, the time constant τ2 is composed of 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 the transistor to obtain the pulse d. This pulse d is output as a horizontal blanking pulse via a diode for preventing backflow.

Therefore, it is possible to create a blanking pulse wider than the horizontal pulse.

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

Then, as described above, a 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 and the left and right images are not aligned due to the variation, By the blanking signal from the blanking pulse generation circuit 3, the RGB signals are blanked at the same horizontal position, and the left and right video areas can be aligned as shown by the shaded area in FIG. As a result, the left and right sides of the image do not fluctuate.

[0023]

However, the RGB
A circuit that affects the blanking signal is required for each signal path of the signal, and at least three identical circuits are required. Therefore, various adjustments and settings must be performed in each circuit, which is troublesome.

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

[0025]

The present invention provides 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 second video signal different from the first video signal and a signal processing means for selectively outputting the video signal by a switching signal for displaying on the same screen and an output video signal of the signal processing means are displayed. Display means, horizontal pseudo signal generation means for generating a horizontal pseudo signal from the horizontal synchronizing signal of the first video signal, and the display means displays the level of the output video signal at least during the period when the horizontal pseudo signal is obtained. (EN) Provided is a television receiver including image invalidating means for setting a cutoff level which is a level not to be set.

In addition, the input first video signal is converted into the first video signal.
In a television receiver displaying on a screen having an aspect ratio different from that of a video signal, a switching for switching a second video signal different from the first video signal with the first video signal and displaying the same on the same screen. A signal processing means for selectively outputting a video signal by a signal, a display means for displaying the output video signal of the signal processing means, and a horizontal pseudo signal for generating a horizontal pseudo signal from the horizontal synchronizing signal of the first video signal. A generation unit, a brightness adjustment unit that is connected to the signal processing unit and controls the brightness of a selected output video signal, and a brightness adjustment invalidation that invalidates the output of the brightness adjustment unit by the horizontal pseudo signal. Means and horizontal pseudo adding means for adding the horizontal pseudo signal to the switching signal, and at least during the period when the horizontal pseudo signal is obtained, the level of the output video signal is increased. 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 switching signal for the on-screen and the output of the adjusting means for adjusting the brightness is invalidated.

[0028]

1 shows a circuit block diagram of an embodiment of the present invention. The same parts as those of the conventional example are designated by the same reference numerals and the description thereof will be omitted.

Reference numeral 6 is a diode which conducts at the H level of the horizontal blanking signal. Reference numeral 7 is a transistor to which a horizontal blanking signal is input via the resistor 8. A horizontal blanking signal is input to the base of the transistor 7 through a resistor 8 and an emitter of the transistor 7 is grounded. When the horizontal ranking signal is at the H level, the DC level of the brightness adjusting means connected to the collector is invalidated. As described above, the luminance adjustment terminal of the video processing circuit 1 is set to a substantially 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 on-screen by a signal b indicating the switching signal Ys to obtain an output video signal. The circuit 1 also separates the horizontal sync signal to obtain the H pulse c.
With this H pulse c, the horizontal blanking pulse generation circuit 4 obtains a horizontal blanking pulse d. The horizontal blanking pulse d is a wider pulse including the front porch portion and the back porch portion before and after the horizontal synchronizing signal.

The horizontal blanking pulse d is added to the switching signal Ys via the diode 6,
The signal e is created and input to the video processing circuit 1 as the 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, and when the horizontal blanking pulse is at H level, the DC adjusted by the brightness adjusting means 5a. The level (brightness level on the screen) is set to almost zero level.

Therefore, when the horizontal blanking pulse d is input to the video signal as shown in FIG. 6F, the DC level adjusted by the brightness adjusting means 5a is invalidated and the CRT is set.
The B0 level, which is a luminance level that cannot be displayed at 3 or lower (that is, equal to or lower than the cutoff level). The video signal becomes the B1 level which is the lowest brightness level currently adjusted by the brightness adjusting means 5a by the signal e which is the switching signal Ys'.

That is, the lowest brightness level disables the brightness adjusting means 5a by the horizontal blanking pulse and becomes the B0 level below the cutoff level, so that the horizontal brightness is at the lowest brightness level in the switching signal Ys'. It becomes a certain B0 level.

The DC level set by the brightness adjusting means 5a is maintained during a period in which an RGB signal such as an on-screen is input, and the switching signal Ys' brings the level to the lowest brightness level B1. Here, although there is no description about the display on the on-screen or the like, any RGB signal or a plurality of RGs is displayed on the on-screen.
It is displayed in the color set by the B signal, and is displayed at the highest luminance level as shown by the hatched portion in FIG.

[0036]

According to the present invention, a CR having an aspect ratio of 9:16 is used.
In a television receiver having T, when displaying a video signal with an aspect ratio of 3: 4, horizontal blanking for preventing left and right image variations is not applied to each of the RGB outputs, so that there is variation in horizontal blanking width. Besides, the circuit for each RGB signal becomes unnecessary and the circuit configuration is simple and the adjustment is easy.

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

[Brief description of drawings]

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

FIG. 2 is a waveform diagram of an example 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 horizontal blanking pulses.

[Explanation of symbols]

 1 Video Processing Circuit 2 RGB Drive Circuit 3 CRT 4 Horizontal Blanking Generation Circuit 5a Luminance Adjusting Means (Variable Resistance) 5b Contrast Adjusting Means (Variable Resistance) 6 Diode 7 Transistor 8 Resistance

Claims (2)

[Claims] 1. A television receiver for displaying an input first video signal on a screen having an aspect ratio different from that of the first video signal, wherein a second video signal different from the first video signal is displayed. A signal processing means for selectively outputting a video signal according to a switching signal for switching to the first video signal and displaying it on the same screen; a display means for displaying the output video signal of the signal processing means; Horizontal pseudo signal generating means for generating a horizontal pseudo signal from a horizontal synchronizing signal of the video signal; and a cutoff level which is a level at which the display means does not display the level of the output video signal for at least the period during which the horizontal pseudo signal is obtained. A television receiver comprising a video invalidating means. 2. A television receiver for displaying an input first video signal on a screen having an aspect ratio different from that of the first video signal, wherein a second video signal different from the first video signal is displayed. A signal processing means for selectively outputting a video signal according to a switching signal for switching to the first video signal and displaying it on the same screen; a display means for displaying the output video signal of the signal processing means; Horizontal pseudo signal generating means for generating a horizontal pseudo signal from a horizontal synchronizing signal of the video signal; brightness adjusting means connected to the signal processing means for controlling the brightness of the selected output video signal; and the horizontal pseudo signal. A brightness adjustment invalidating means for invalidating the output of the brightness adjusting means, and a horizontal pseudo adding means for adding the horizontal pseudo signal to the switching signal, Serial television receiver horizontal pseudo signal period obtained of which is characterized in that the cut-off level is a level that does not display the display means the level of the output video signal.