JPH0810986Y2 - Television receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a television receiver,
In particular, a larger aspect ratio than the one that is currently popular (horizontal: vertical aspect ratio of 4: 3), for example, vertical ×
The present invention relates to an improvement of a television receiver having a wide size screen such as a 16: 9 wide high-definition screen.

[Prior art] In high-definition TV, the aspect ratio of the screen is high.
It is 16: 9, which is a landscape screen compared to the conventional 4: 3 screen. Therefore, if a conventional NTSC video signal having an aspect ratio of 4: 3 is directly input to a television receiver having a 16: 9 screen, a horizontally stretched reproduced image will result.

Therefore, a video signal with an aspect ratio of 4: 3 is time-compressed to 3/4 in the horizontal direction, and a constant gray signal is added to the remaining 1/4 horizontal scanning period. By this, 1
An image with an aspect ratio of 4: 3 can be normally obtained on a screen with an aspect ratio of 6: 9.

FIG. 3 (A) shows an example of a conventional video signal having an aspect ratio of 4: 3. In the figure, the signal S10 is a luminance signal and the signal S12 is a horizontal synchronizing signal. On the contrary,
A signal obtained by time compression of 3/4 in the horizontal direction is as shown in FIG. That is, the luminance signal becomes like S14, and before and after that, appropriate gray signals S16 and S1
8 is added. These processes are performed in units of 1H for one horizontal scanning period.

As a result, the image Q having the aspect ratio of 4: 3 shown in FIG. 7C is reproduced on the screen having the aspect ratio of 16: 9 with the same aspect ratio as shown in FIG. Become. Then, on the left and right of the screen, there are gray parts or non-display parts Q10 and Q12 by the gray signals S16 and S18.

Although the above example is mainly the case of the luminance signal in the video signal, color difference signals such as R (red) -Y (luminance), B (blue) -Y and R, G (green), B The same can be applied to the case of color signals. At this time, for example, if the color signal is subjected to a certain operation, the non-display portions Q10 and Q12 can be colored in a specific manner.

By the way, in a normal television receiver, a beam limiter circuit is provided so that the beam current in the CRT does not exceed a predetermined allowable value, whereby the brightness, contrast or color saturation of the reproduced image is increased. It is designed to be controlled within a predetermined range.
FIG. 4 shows an example of such a conventional device. In the figure, it is output from a video signal processing unit (not shown).
Video signal with 4: 3 aspect ratio (see Fig. 3 (B))
Are input to the compression processing circuit 10. The output side of this compression processing circuit 10 is a level control circuit.
It is connected to the input side of 12 and the output side of the level control circuit 12 is connected to the CRT 14 having an aspect ratio of 16: 9. Beam current value of CRT14
The detection output side is connected to the input side of the level control circuit 12.

The operation of the related art as described above will be explained as follows:
A video signal having an aspect ratio of 3 is input to the compression processing circuit 10, where the time compression processing of 3/4 as shown in FIG. 3 is performed. The processed signal undergoes necessary level adjustment in the level control circuit 12. That is, the level control circuit 12 controls the brightness, contrast, and color according to the beam current value in the CRT 14 detected by the beam detection circuit 16.

[Problems to be Solved by the Invention] However, in the above-described conventional techniques, the non-display portions Q10 and Q12 existing on the left and right of the time-compressed image (see FIG. 3D) on the CRT 14 also have the fourth feature. Since the beam limit operation shown in the figure is performed, the non-display areas Q10, Q1
There is an inconvenience that the brightness and color density of 2 also change.

For example, in the case of a bright screen where the average brightness of the image Q is high, the beam limiter operates to reduce the brightness and contrast of the video signal. Therefore, the brightness of the non-display portions Q10 and Q12 also becomes dark. On the contrary, in the case of a dark screen where the average brightness of the image Q is low, the beam limiter does not operate. For this reason, the non-display portions Q10 and Q12 are relatively bright and have a strong color depth.

Average luminance of such video signals (APL, Average Pictur
The variation of the non-display areas Q10 and Q12 due to e Lebel) is unpleasant when viewing an image with an aspect ratio of 4: 3 on a CRT with an aspect ratio of 16: 9, which is not preferable in terms of quality.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a television receiver capable of improving the quality as a whole by preventing the fluctuation of the non-display portion due to the beam limiter to be constant. , That is the purpose.

[Means for Solving the Problems] The present invention has a display unit having a first aspect ratio, and time-compresses a video signal of the second aspect ratio while taking into consideration the difference in the aspect ratio, and a non-video portion. And a fixed level signal generating means for outputting a signal for fixing the beam intensity of the display means in a television receiver which supplies the video signal to the display means in which the beam limit operation is performed. And a video discriminating means for detecting the non-video portion, and a switching means for setting the beam intensity by the output of the fixed level signal generating means for the non-video portion according to the discrimination result. It is a thing.

[Operation] According to the present invention, for the non-video signal portion of the time-compressed video signal, the beam intensity is set by the fixed level signal generating means instead of the normal beam limit operation. Therefore, in the non-video signal portion, the beam intensity is constant regardless of the display content of the video portion.

[Embodiment] An embodiment of a television receiver according to the present invention will be described below with reference to the accompanying drawings. The same reference numerals are used for the same or corresponding components as those of the above-mentioned conventional example.

FIG. 1 shows the main part of one embodiment of the present invention. In the figure, a video signal having an aspect ratio of 4: 3 output from a video signal processing unit (not shown) is input to the compression processing circuit 20. This compression processing circuit
20 has an identification pulse output section 22 for identifying the presence or absence of a video signal.

Next, the output side of the compression processing circuit 20 is connected to the input side of the level control circuit 12, and the output side of the level control circuit 12 is connected to one switching input side of the changeover switch 24. Further, the output side of the fixed level signal generator 26 is connected to the other switching input side of the changeover switch 24. Furthermore, the output side of the above-mentioned identification pulse output section 22 is connected to the switch control input side of the changeover switch 24.

Next, the output side of the changeover switch 24 is connected to the CRT 14, and the beam current of this CRT 14 is detected by the beam detection circuit 16. This beam detection circuit
The detection output side of 16 is the level control circuit 12 described above.
Is connected to the control input side of.

Of the above units, the compression processing circuit 20 performs the time compression processing of 3/4 as described with reference to FIG. 3 on the video signal having the aspect ratio of 4: 3, similarly to the above-mentioned conventional technique. It is a thing. The identification pulse output unit 22 outputs an identification pulse indicating an image display period. For example, a signal having a theoretical value “H” is present during a period when an image signal is present, and a signal having a logical value “L” is present during a period when no image signal is present. It is designed to be output as an identification pulse. The changeover switch 24 is switched to the level control circuit 12 side when the control signal has a logical value "H", and switched to the fixed level signal generator 26 side when the control signal has a logical value "L". ing.

Next, the overall operation of the above embodiment will be described with reference to the time chart of FIG. 4: 3 input
The video signal having the aspect ratio is as shown in FIG. In the figure, S10 is a luminance signal and S12 is a horizontal synchronizing signal. When this is input to the compression processing circuit 20, the time compression processing described with reference to FIG.
Gray signals S16 and S18 are added to each of them (see FIG. 7B). The compressed video signal is input to the level control circuit 12. Then, the beam limiter is controlled based on the detection value of the beam detection circuit 16 including the gray signals S16 and S18.

On the other hand, in the identification pulse output unit 22, in the time-compressed video signal, the logical value is “H” in the period in which the luminance signal S14 exists, and in the period including the other gray signals S16, S18 and the horizontal synchronization signal S12. An identification pulse having a logical value of "L" (see FIG. 7C) is output to the changeover switch 24 as a changeover control signal.

Therefore, the changeover switch 24 can be changed over as shown in FIG. That is, the output of the level control circuit 12 is input to the CRT 14 via the changeover switch 24 during the period when the luminance signal S14 is present in the video signal. Further, during the non-video period including the other gray signals S16 and S18, the output of the fixed level signal generator 26 is the changeover switch 24.
Is input to CRT14 via.

As a result, the beam limit operation by the level control circuit 12 and the beam detection circuit 16 is performed only in the video period in which the luminance signal S14 exists, and in the other periods, the fixed level output from the fixed level signal generator 26 (the same). (See FIG. (E)). That is, even if the brightness and contrast of the video signal change, the brightness and contrast of the gray signals S16 and S18, that is, the non-display areas Q10 and Q12 (see FIG. 3D) in the screen are constant. Becomes

It should be noted that the present invention is not limited to the above-described embodiments, and includes, for example, the following ones.

(1) Although the above-described embodiment is an embodiment mainly for a luminance signal of a video signal, it can be similarly applied to a color signal.

(2) In addition, in the above-described embodiment, all the periods without the video signal are fixed level, but the period of the synchronizing signal (or blanking) is excluded so as not to have the fixed level, for example, in order to guarantee the operation in the subsequent stage. You may do it.

(3) Furthermore, although the above-mentioned embodiment is the case of the NTSC system,
It is also applicable to the systems such as PAL and SECAM.

(4) In addition, the circuit configuration can be variously modified so as to achieve the same operation. For example, the aspect ratio of CRT is not limited to 16: 9.

[Advantages of the Invention] As described above, according to the television receiver of the present invention, the beam intensity of the display means in the non-image portion of the screen is set to a fixed level, so that the overall image quality is improved. The effect is that you can.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a television receiver according to the present invention, FIG. 2 is a time chart showing the operation of the embodiment, and FIG. 3 is a compression process of image signals having different aspect ratios. FIG. 4 is a configuration diagram showing a main part of a conventional television receiver. 12 ... Level control circuit, 14 ... CRT (display means), 20 ... compression processing circuit, 22 ... identification pulse output section (video identification means), 24 ... changeover switch (changeover means),
26: Fixed level signal generator (fixed level signal generating means).

Claims (1)

[Scope of utility model registration request] 1. A display device having a first aspect ratio, wherein a non-video portion is formed by time-compressing a video signal having a second aspect ratio while taking into consideration the difference in aspect ratio. A television receiver which supplies the display means performing a beam limit operation, a fixed level signal generating means for outputting a signal for fixing the beam intensity of the display means, and the non-video portion are detected. A television receiver comprising: a video discriminating means; and a switching means for setting a beam intensity by the output of the fixed level signal generating means for a non-video portion according to the discrimination result.