JPH02143783A - Interchangeable television receiver - Google Patents

Abstract

PURPOSE:To prevent baking of a CRT without deteriorating ease of observation of a video image displayed in the middle of the screen by giving a somewhat lower brightness to the circumferential frame picture above and under the display screen than the average brightness of the video image. CONSTITUTION:When a wide aspect video signal is introduced from an input terminal 2, the signal is compressed in the middle of the vertical scanning period and the video signal of the front edge and the tail edge of the vertical scanning period not including the picture information is brought into a somewhat lower level than the average picture level of the video signal in the middle and outputted from a video signal synthesis circuit 6. The wide aspect video is displayed in the middle of the CRT display screen of the display device 4 and the brightness of the upper and lower circumferential frame picture is somewhat lower than the average brightness of the wide aspect video image. Thus, the case of observation of the picture is not deteriorated and baking of the CRT is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a compatible television receiver that is compatible with the NTSC system, high-definition television control system, wide aspect television system, and the like.

(Prior Art) High-definition television receivers and wide-aspect television receivers, which are expected to become popular these days, have different screen aspect ratios from those of current standard television receivers. Due to the difference in aspect ratio of the video signals supplied to these television receivers, for example, the video signal to be supplied to a wide aspect television receiver (
If a wide aspect video signal (hereinafter referred to as a wide aspect video signal) is displayed on a current standard revision receiver, the video will be vertically long. Therefore, conventionally, television receivers that can receive video signals with different aspect ratios have been developed.

FIG. 2 is a block diagram showing the circuit configuration of such a conventional compatible television receiver. In Figure 2 [. [It is compatible with current standard television receivers and other wide-assigned TV receivers, and the asbestos ratio of the display screen is the same as that of current standard television receivers.

A video signal for current standard digital video reception (hereinafter referred to as a standard video signal) and a wide aspect video signal are introduced into the human-powered QQR1.2. When introducing a standard video signal from the input terminal 1, the method switching circuit 3 selects the input terminal 1, and the standard video signal from the input terminal 1 is supplied to the Daysbu 1 Noise Equipment 4 via the method switching circuit 3. be done. In this case, the picture tube (CRT) of display device d4
) displays a normal image (hereinafter referred to as standard image).
is displayed.

On the other hand, the wide-aspect vector 1-video signal introduced from the input terminal 2 is supplied to the signal conversion circuit 5. Signal conversion circuit 5
compresses the video signal to the center of the vertical scanning period and sends it to the video signal synthesis circuit 6. The video signal synthesis circuit 6 applies one novel set in the peripheral frame homemade level setting circuit 7 to the video signals at the leading and trailing edges of the vertical scanning period. When introducing a wide asvector 1-video signal from the input terminal 2, the system switching circuit 3 is
is selected, and the video signal from the video signal synthesis circuit 6 is supplied to the 1st noise device 4. The 1st noise device 4 processes the wide aspect video signal.
Display wide aspect video on the display screen.

FIG. 3 is an explanatory diagram for displaying a wide aspect image displayed on the display screen of the CRT of the display device 4. Figure 3 (a) (shows the aspect ratio of the image; Figure 3 (1)) shows the wide aspect images 9 and 1 displayed on the CRT display screen 8 (42) of the display device 4. The peripheral frame image @10 is shown.

1111 As mentioned above, the video signal number is compressed to the wide asvector 1, and the video signal number is compressed to the center between the 1-fold direct scan brightness, and as shown in Fig. 3 (b
)! , 2, the leading edge and (edge) of the 3° vertical scanning period in which the wide ast vector 1-image 9 appears at the center of the CRI display screen E3 in the vertical direction are fixed at a predetermined level, and the screen 8 The top image appears as the bottom peripheral frame image 10. As a result, the wide asperity vector 1 that appears on the display screen
- The aspect ratio of the image 9 and the wide aspect image of FIG. 3(a) is the same, and an image with 41 degrees of distortion is obtained.

On the other hand, the wide asbestos l-7 revision receiver and the current (j
Standard) - If you have adopted a display device that has 17 compatibility with a standard image receiving jacket () and a display screen with a wide aspect ratio of wide aspect images, input terminals 1 and 2 in Figure 2. sends the video signal and standard video 1;- to people wide 7 scale 1. For a standard video signal, the video signal is compressed to the center of the horizontal scanning period, and the edges and recovery edges of the horizontal scanning period 1) are brought to a predetermined level.

FIG. 4 is an explanatory diagram for explaining the standard video displayed on the display screen of the display device in this case.6 FIG. (b) shows the standard video 12 and left and right peripheral frame images 13 displayed on the display screen 11 of the display device.

The +1 video signal is compressed by the center km I1 of the horizontal scanning period, and the leading and trailing edges of the horizontal scanning period are set to a predetermined level and t.
Therefore, the standard video 12 is displayed in the center of the display screen 11 for video display to the wide aspic 1, and the / of the display screen is
On the right, left and right peripheral frames 1iii image 13 of a predetermined level are shown.

In this way, the video signal is converted to (f
By displaying an image at a reduced size in the center of the display screen and displaying a frame image of a predetermined level around the periphery, an image with a jnosvector ratio of η; is displayed. - [, bottom and left and right peripheral frame images (ilo, +3 Do it again, center image 9.12
In general, the black level is set to 1 for ease of viewing.

In this way, when displaying images with different aspect ratios, a predetermined black level will be displayed on the top and ktj of the display screen for a relatively long period of time. Therefore, in the central part of cr
・Although it is 1, the peripheral areas such as left and right and below -F are irradiated for less time, so the degree of burn-in in the center of the CRT increases. When such a burn-in phenomenon occurs, there is a problem in that it becomes an obstacle when using the entire display screen.

(Problems to be Solved by the Invention) As described above, in the above-mentioned conventional compatible television set, the top and bottom or left and right sides of the screen are fixed at a predetermined black level for a long time in order to make the image easier to see. There was a problem that a CRT burn-in phenomenon occurred.

The present invention has been made in view of such problems, and includes:
To provide a U-type television receiver capable of preventing the occurrence of CRT burn-in without deteriorating the visibility of images.

[Structure of the Invention] (Means for Solving the Problems) The present invention is based on the aspect ratio of the display screen. A signal conversion means that introduces a video signal with an aspect ratio of ζ, compresses and outputs the introduced video signal based on the difference from the 7 aspect ratio of the display screen, and detects an average image level from the output of this signal conversion means. level detecting means for outputting a control signal based on the detected value; image level setting means for setting an image level 6 lower than the average image level under the control of the control signal; The apparatus further includes a signal synthesizing means for applying the image level set by the image level setting means to the video signal from the signal converting means and outputting the same during a period when no information is included.

(Function) In the present invention, the level detection means detects the average image level of the video signal and outputs a control signal, and the image level setting means sets an image level lower than the average image level. The signal synthesizing means introduces a compressed video signal based on the difference in aspect ratio, and during a period when no image information is included, gives the video signal an image level set by the image level setting means and outputs it. As a result, for example, an image converted to a 7 aspect ratio is displayed in the center of the display screen, and images at the level set by the image level setting means appear at the top, bottom, left, and right of the display screen. The upper, lower, left and right peripheral areas of the screen also have a brightness close to that of the center, and the degree of burn-in in the central and peripheral areas of the CRT is similar. Therefore, undesired reduction in burn-in can be prevented.

(Example) Hereinafter, the present invention will be described in detail based on the drawings. FIG. 1 is a block diagram showing an embodiment of a compatible television receiver according to the present invention. In FIG. 1, the same components as in FIG. 2 are given the same reference numerals. This embodiment is compatible with wide aspect television receivers and current standard television receivers, and is adapted to devices where the display screen of the display device has the same aspect ratio as the current standard television receiver. be.

A standard video signal is introduced into input terminal 1, and a wide aspect video signal is introduced into input terminal 2.

System switching circuit 3, display device 4, signal conversion circuit 5
The configuration of the video signal synthesis circuit 6 is the same as the conventional one. That is, when the standard video signal is introduced from the input terminal 1, the system switching circuit 3 selects the input terminal 1, supplies the standard video signal to the display device 4, and introduces the wide aspect video signal from the input terminal 2. In this case, the wide aspect video signal from the video signal synthesis circuit 6 is supplied to the display device 4. Based on the difference in aspect ratio, the signal conversion circuit 5 compresses the video No. 15 portion of the wide angle video signal to the center of the vertical scanning period and outputs it. As a result, all image information of the wide aspect video signal is displayed on the display screen. Video signal synthesis circuit 6 (for the video signal in the vertical scanning period that does not include image information,
After that, the level provided by the peripheral frame image level setting circuit 15 is applied and output to the C method switching circuit 3.

In this embodiment, the output of the UG signal 8 conversion circuit 5 is APL.
It is also supplied to the detection circuit 14. The APL detection circuit 1/I detects the average image level (hereinafter referred to as APL) from the level of the bright single signal from the signal conversion circuit 5, and converts the control signal based on this detected value to the peripheral frame image level. It is applied to the setting circuit 15. The peripheral frame image level setting circuit 15 is
Control 2+1 (, j Sets the signal level given to the C video low-signal synthesis circuit 6 every month. As a result, in the video signal synthesis circuit 6, the video signal during the period when image information is not included is set. G,! A P A slightly lower level than L is given and output.

In the embodiment device configured as described above, when a standard video signal is introduced from the input terminal 1, the standard video is displayed on the display screen of the display device 4, as in the conventional case. On the other hand, when a wide aspect video signal is introduced from input terminal 2, the wide aspect video signal is compressed at the center of the vertical scanning period, and the leading and trailing edges of the vertical ICJ scanning period that do not contain image information are compressed. video signal C
The video signal is outputted from the video signal synthesis circuit 6 at a level slightly lower than the APL of the video signal of medium heat. A wide aspect image is displayed at the center of the CRT display screen of the display device 4 (see FIG. 3(b)), and the upper and lower peripheral frame images are images with slightly lower brightness than the average brightness of the wide aspect image. .

As described above, in this embodiment, the peripheral frame images at the top and bottom of the display screen have a slightly lower luminance than the average luminance of the video, so the display screen is medium-high! l! Since the image is always easy to see and changes with changes in average brightness, it is possible to prevent the occurrence of burn-in phenomenon on CRTs.

Note that the present invention is not limited to the above embodiments,
For example, it is obvious that the present invention can be applied to devices that have a display screen with the same aspect ratio as a wide aspect video and are compatible with current standard television receivers and wide aspect television receivers.

[Effects of the Invention] As explained above, according to the present invention, the burn-in phenomenon of a picture tube constituted by a CRT or the like can be prevented without deteriorating the visibility of the IIJ image displayed at the center of the screen. be able to.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a compatible television receiver according to the present invention, FIG. 2 is a block diagram showing a conventional compatible television receiver, and FIG. 3 is a wide aspect diagram displayed on a display screen. Explanatory diagram for explaining the video, 4th
The figure is an explanatory diagram for explaining the standard video displayed on the display screen. 1.2...Input terminal, 3...Method switching circuit, 4...
・Display device, 5... signal conversion circuit, 6...
Video signal synthesis circuit, 14... APL detection circuit, 15.
...Peripheral frame image level setting circuit.゛~Table゛, :12 Fig. 1 Fig. 2 1゜(b) Fig. 3(b) Fig. 4

Claims (1)

[Scope of Claims] A signal conversion means for introducing a video signal having an aspect ratio different from that of a display screen, compressing the introduced video signal based on the difference from the aspect ratio of the display screen, and outputting the signal; Level detecting means detecting an average image level from the output of the converting means and outputting a control signal based on the detected value; Image level setting means controlling by the control signal and setting an image level lower than the average image level; and signal synthesizing means for applying the image level set by the image level setting means to the video signal from the signal converting means and outputting the same during a period when the video signal from the signal converting means does not include image information. A compatible television receiver featuring: