JPH0787416A - Television receiver - Google Patents

Abstract

PURPOSE:To prevent a title from extending over to the outside of a cathode ray tube by discriminating a video signal for a non-picture area called a latter box and using a discrimination signal so as to select an image display mode where the image of the non-picture area is least displayed when a video image whose aspect ratio is 3:4 is displayed with the cathode ray tube whose aspect ratio is 9:16. CONSTITUTION:When a latter box type signal such as a cinema size signal of a movie or the like is mixed in a broadcast signal whose aspect ratio in 3:4 and the signal is displayed in the zoom mode by a television receiver whose aspect ratio is 9:16, a title may extend overed from the display area of a cathode ray tube. The state of a F line of a lower non-picture area is detected after the mode is switched to the zoom mode. When any signal is included in the F line, it is discriminated that the title is in existence and a signal representing the presence of the title is outputted from an aspect ratio discrimination: a title detection circuit 8 to a main CPU 7. The main CPU 7 increases the vertical deflection speed by the F line in which the signal representing the title is in existence.

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 an 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 according to the broadcasting standard 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 some still have a 3: 4 broadcast. Further, some broadcasts have an aspect ratio of 3: 4 and have no image areas at the top and bottom of the screen. The screen is called, for example, a cinema size (or cinemasco size), and a video signal of 36:68 is added to a 3: 4 (51:68) image, and the remaining part is a video signal composed of a non-image area. is there.

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.

First, as shown in FIG. 9, there is a mode (hereinafter referred to as a normal mode: a) in which a video having a 3: 4 aspect ratio is displayed as it is as shown in FIG. Next, fit the screen size in the horizontal direction and expand it in the vertical direction at the same rate, and the image protrudes from the upper and lower screens, and the circularity ratio (which shows distortion in the vertical and horizontal directions when a perfect circle is drawn) is set to 1.
There is a mode (hereinafter referred to as zoom mode: b in the same figure) for keeping and displaying. In addition, there is a mode (hereinafter, referred to as full mode: c in the same figure) that does not expand in the vertical direction, fits the screen size in the horizontal direction, and does not set the roundness to 1. further,
There is a mode in which the zoom mode and the full mode are combined to display a horizontally long image on the left and right portions of the screen while maintaining the circularity at the center of the screen (hereinafter referred to as panorama mode: FIG. D).

Then, in a 9:16 CRT,
When the input video signal is a video of a 3: 4 screen (hereinafter referred to as a regular mode), it may be displayed in a normal mode or a panoramic mode. In addition, a letterbox type screen in which an input video signal has a non-image portion above and below a cinema size or the like may be displayed in a zoom mode.

Also, the viewer switches the display mode by selecting and switching each mode.

[0010]

However, since it is necessary for the viewer to select the optimum display mode according to the broadcast and the source to be supplied, it is necessary to set each time the broadcast and the source change. It can be annoying.

Further, when viewing a video signal having subtitles called open captions in the non-image area below the letterbox signal in the zoom mode, the letterbox video signal has various aspect ratios, and the aspect ratio of the video is different. Depending on the ratio, the subtitles may stick out of the cathode ray tube. Therefore, in order to display this subtitle, it is necessary to move the entire screen upward and display the subtitle at the bottom without breaking it.

[0012]

The present invention provides a television receiver for displaying an input video signal on a screen having an aspect ratio different from that of the video signal.
Video signal detecting means for detecting low-frequency video signals in a plurality of areas provided on the screen, video signal change detecting means for detecting changes in the low-frequency video signal in the areas, and output of the video signal change detecting means And an image discriminating means for discriminating the presence or absence of an image, and a display adjusting means for changing the aspect ratio of the screen display of the video signal by the output of the image discriminating means. Provided is a television receiver which discriminates a video signal having an area and displays the video signal on the screen in a screen display mode in which the display of the non-image area is minimized by the discrimination signal.

Further, in a television receiver which displays an input video signal on a screen having an aspect ratio different from that of the video signal, the low frequency video signal in at least two areas provided on the screen is detected. Video signal detection means, video signal change detection means for detecting a change in the low frequency video signal in the area, image discrimination means for discriminating the presence or absence of an image by the output of the video signal change detection means, and the image discrimination Display adjustment means for changing the aspect ratio of the screen display of the video signal by the output of the means, and a non-image area discrimination means for discriminating a video signal having a non-image area where there is no image on a part of the screen; Provided is a television receiver including a caption discriminating means for discriminating a change in a video signal in a non-image area as a caption signal.

Further, in a television receiver which displays an input video signal on a screen having an aspect ratio different from the aspect ratio of this video signal, the low frequency video signal in the area at least two places provided on the screen is detected. Video signal detection means, video signal change detection means for detecting a change in the low frequency video signal in the area, image discrimination means for discriminating the presence or absence of an image by the output of the video signal change detection means, and the image discrimination Display adjustment means for changing the aspect ratio of the screen display of the video signal by the output of the means, and a non-image area discrimination means for discriminating a video signal having a non-image area where there is no image on a part of the screen; A caption discriminating means for discriminating a change in the video signal in the non-image area as a subtitle signal so that the non-image area is displayed least And displays the screen display mode, there is provided a television receiver which is adapted increase the scanning speed of the display position for displaying the subtitle by the output of the caption judging means.

Further, in a television receiver which displays an input video signal on a screen having an aspect ratio different from that of the video signal, the low frequency video signal in the area at least two places provided on the screen is detected. Video signal detection means, video signal change detection means for detecting a change in the low frequency video signal in the area, image discrimination means for discriminating the presence or absence of an image by the output of the video signal change detection means, and the image discrimination Display adjustment means for changing the aspect ratio of the screen display of the video signal by the output of the means, and a non-image area discrimination means for discriminating a video signal having a non-image area where there is no image on a part of the screen; A caption discriminating means for discriminating a change in the video signal in the non-image area as a caption signal, and discriminating time between the image discriminating means and the caption discriminating means There is provided a television receiver, characterized in that shorter than the program time.

[0016]

According to the present invention, a blanking (no image) area is determined by detecting a video signal in an arbitrary horizontal scanning period, and the aspect ratio of the currently received video is determined.

[0017]

1a is a block diagram showing a television receiver according to an embodiment of the present invention.

Reference numeral 1a is an input terminal to which a television signal demodulated by the receiving circuit is input, 1b is an input terminal to which a composite video signal is input from a video reproducing apparatus such as a video reproducing apparatus, and 1c is a luminance. / Color separation (Y
/ C separated) luminance (Y) signal input terminal, 1
Reference numeral d is a terminal to which a color (C) signal separated by Y / C is input.

Reference numeral 2 denotes a selection switch for selectively switching the input signals respectively input by a control signal from a circuit for selecting and switching (a tuning CPU, etc.) and outputting them as a brightness signal and a color signal.

Reference numeral 3 denotes a Y / C separation circuit for separating a composite video signal such as a television signal or a composite video signal input to the selection switch 2 into a luminance signal and a color signal in order to match the output of the selection switch 2. Is.

Reference numeral 4 is for inputting the luminance signal and the color signal output from the selection switch 2 for synchronizing separation, separating and outputting a horizontal synchronizing signal and a vertical synchronizing signal, and R, G, B.
This is a video chroma processing circuit that converts and outputs the signal.

Reference numeral 5 denotes R from the video chroma processing circuit 4,
This is a CRT drive circuit that inputs the G and B signal outputs and drives the CRT 6.

Reference numeral 7 denotes a main CPU which controls a deflection circuit and the like (not shown) for switching each screen size according to the horizontal synchronizing signal and the vertical synchronizing signal from the video chroma processing circuit, and also serves as a channel selection CPU.

Reference numeral 8 denotes an aspect ratio discriminating / caption detecting circuit for discriminating the aspect ratio from the luminance signal, the horizontal synchronizing signal and the vertical synchronizing signal and detecting the subtitle position.

The aspect ratio discrimination / caption detection circuit 8 has a structure shown in FIG.

8a is an input terminal to which the luminance signal from the selection switch 2 is input, 8b is an input terminal to which the horizontal synchronizing signal from the video chroma processing circuit 4 is input, and 8c is a vertical synchronizing signal from the video chroma processing circuit 4. Is an input terminal to which is input.

Reference numeral 81 is a low-frequency pass filter (hereinafter referred to as LPF) for removing noise components of the input luminance signal, and 82 is A / A for converting the video luminance signal processed by the LPF 81 into a 6-bit digital signal. D conversion circuit,
Reference numeral 83 is a clamp pulse generation circuit that generates a clamp pulse from the input horizontal synchronizing signal in order to clamp the video luminance signal at the pedestal level in the A / D conversion circuit 82. Reference numeral 84 is a determination CPU that receives the upper 5 bits of the digitally converted luminance signal and determines the period of the video signal, that is, the aspect ratio and the caption displayed outside the image, according to the input data. is there.

The aspect discriminating signal which is the output of the discriminating CPU is output from the terminal 8d, and the subtitle detecting signal which is the other output is output from the terminal 8e and is input to the main CPU 7, respectively. In addition, this determination CPU 84
Outputs a clock for A / D conversion, and A / D conversion is performed by this clock.

Here, the upper 5 bits of the digital signal are used because the lower 1 bit is affected by noise and the like.
This is because it is unstable. Moreover, ± 1 is judged as an error and treated as the same. Therefore, for example, if (00010 ×) 2 is used as the reference, (00001 ×) 2
And (00011 ×) 2 are determined to be the same as the reference. Here, x is the sixth bit and may be "0" or "1".

Next, the operation will be described with reference to FIG.

The input television signal or composite video signal is separated into a luminance signal and a chrominance signal by the Y / C separation circuit 3 via the selection switch 2. Then, the luminance signal and the color signal are input to the selection switch 2 again,
The signal and the luminance signal and the color signal input from the S terminal are selectively switched and output.

Then, the luminance signal and the chrominance signal are input to the video chroma processing circuit 4, where the vertical synchronizing signal and the horizontal synchronizing signal are separated and converted into RGB signals for use in the CRT 6.

The RGB signal is input to the drive circuit of the CRT and converted into an RGB signal for driving the CRT 6. The CRT 6 is driven by the RGB signals, and the input signal is displayed as an image on the cathode ray tube.

On the other hand, the luminance signal from the selection switch 2 is taken into the aspect ratio discrimination / caption detection circuit 8, A / D-converted at the timing of the horizontal synchronizing signal and the vertical synchronizing signal, and the aspect ratio is discriminated / determined by the digital video signal. Detect subtitles. The discrimination and detection output is input to the main CPU 7, converted into a control signal, and supplied to a deflection circuit or the like. The control signal is a control signal for adjusting the horizontal deflection,
A control signal for adjusting the vertical deflection, a control signal for adjusting the S-shaped correction for the sawtooth wave for deflection, and the like.

FIG. 2 shows a case where the cinema mode is enlarged and displayed on a 9:16 CRT. The CRT display area includes a cinema mode image display area and a non-image area in which upper and lower images are not displayed. The figure a is AF
6 lines, and b is judged by 4 lines of A, B, E, and F. Here, the line may be a two-dimensional area shown by horizontal scanning lines or the like or a three-dimensional area shown by a plurality of horizontal scanning lines.

In this figure, it is assumed that the A line and the F line are set to the scanning area for scanning the non-image area, and the B to E lines are set to the scanning area for scanning the video display area.

As a method for discriminating the aspect ratio of the image currently displayed, the data in the scanning areas of the A line and the F line are detected, and the image data has a constant low brightness level, and B When at least one of the video data from the line to the E line is different, the aspect ratio can be determined to be horizontally long, and it can be determined that the video signal (cinema mode) includes blanking regions above and below. Further, when either of the above two points is not established, it cannot be determined that the aspect ratio is horizontally long, and it cannot be considered that the mode is the cinema mode.

Further, in the caption detection, when it is judged that there is a horizontal aspect ratio and it is judged that there is some signal in the lower non-image area, the caption is detected.

That is, in the aspect ratio discrimination and caption detection, the video data at the discriminable position are compared, and if all have a certain value, it is determined that the area is a non-image area with no video. , Aspect ratio discrimination and caption detection.

The discrimination process will be described with reference to the flowchart of FIG. First, the determination process starts in step S1. Regardless of which aspect ratio the current video signal has, the normal mode is set in step S2. At this time, if it is displayed on the 9:16 CRT,
If the video signal has an aspect ratio of 3: 4, it is shown in Fig. Aa.
It becomes a screen with no image area on the left and right like 9:16
If the video signal has the aspect ratio of, the screen becomes a normal 9:16 screen that fills the CRT.

Then, in step S3, it is determined whether the A / D-converted video data of the A line shown in FIG. 2 are all the same. If the video signal is 3: 4 or 9:16, there is some video signal on the A line, and this determination is OK.
However, the initial state is restored in step S3.

However, in a letterbox size image having a non-image part at the top and bottom such as a cinema mode, the A-line is located in the no-image part and all have the same brightness level, so the process proceeds to step S4.

In step S4, it is determined whether or not the data which are all determined to be the same in step S3 are equal to or less than 1/2 of the maximum brightness level Max. This is because if it is higher than this, the actual image is considered to be a background image or the like in which the high luminance level does not change, such as the sky or a wall.
Further, although set to 1/2 of MAX, this value may be set to a smaller value as long as the level of the non-image area can be discriminated.

In step S5, the central portions B and E (FIG. 2a)
In the case of, it is determined whether or not any one of the line data is different. For example, if the A line has the same brightness level and is Max / 2,
When the B and E lines have the same brightness level and Max / 2, it means that there is no signal input or there is no image. Therefore, in order to prevent the aspect ratio of the screen from being unintentionally converted by mistakenly considering it as the letterbox size, the initial state is restored. Therefore, the presence / absence of an image can be determined by discriminating the central portion of the screen.

In step S6, it is determined whether the video data of the F line are all the same. Same as step 3:
If it is a video signal of 4 or 9:16, there is some video signal in the F line, and this determination is not OK, and the initial state is restored in this step.

Next, in step S7, the data of the A line (here, all the same data are already here) and the data of the F line (here, all the same data are already here) are compared, and the respective lines are the same. Determines whether the brightness level is constant.

If they are the same, it can be determined from these processes that it is the letterbox mode, and that it is desirable to display in the zoom mode.

As a result, the aspect ratio discrimination / caption detection circuit 8 outputs a signal for converting the aspect ratio and controlling and selecting the zoom mode (performed in step S8).

In the zoom mode, the positions of the A, B, (C, D,) E and F lines fluctuate with respect to the position of the screen because they are enlarged vertically and horizontally. The line above the center is positioned further upward, and the line below is positioned further downward.

In step S9, as in step S3, A
It is determined whether the data on the lines are all the same. Here, when a video signal other than the letterbox is input in the zoom mode, that is, when a video signal having no upper and lower non-image areas is input, the determination is made so as to return to the normal mode.

In step S10, it is determined whether the video data of the A line when the zoom mode is set is equal to the current video data of the A line. If they are equal, it can be determined that the letterbox size remains as it is, but if they are not equal, it is considered that the letterbox size image has been canceled, and a determination is made to return to the normal mode.

In step S11, the process is executed when all the A lines are the same and the same as the data when the zoom mode is set, and it is determined whether all the F line image data are the same as in step S6. If they are the same, it can be continuously determined that the zoom mode is set.

In step S12, it is determined whether the video data of the F line when the zoom mode is set is equal to the current data. If they are equal, it can be determined that the letterbox size remains, and the process returns to step S8 to repeat the zoom mode step.

However, when NO is determined in step S9 and step S10, step S1 is performed for the F line as in step S11 and step S12.
4, the determination is made in step S15, and if NO here as well, it is considered that the letterbox size has been canceled, and the process returns to step S2.

However, if both of the steps S14 and S15 are YES, it means that only the A line is different, but to prevent misidentification, the process returns to the zoom mode setting step S9 again.

On the other hand, if NO in steps S11 and S12, it can be determined that there is some signal in the F line. And A line is letterboxed and F
When there is video data on the line, it can be determined that there is a caption signal. Therefore, the process proceeds to step S13 of subtitle setting, and subtitles are set. A signal with caption is output from the aspect ratio discrimination / caption detection circuit 8 and is used as a caption in command to the main CPU. And
The subtitle in state is maintained, and the process returns to step S9 of zoom mode setting. This subtitle in state is held until the normal mode is restored.

In this flow chart, the A and F lines which are non-image areas are detected during letterboxing, and the B to E lines at the center of the screen are detected to determine the current image size.

Next, a method of line discrimination (steps S3, S
5, S6, S9, S11, S14) will be described.

As a first embodiment, there is a method of making a determination by a plurality of horizontal scanning lines extending over a plurality of frames. In the screen of FIG. 2b, this may be done with 4 horizontal scanning lines for the A line, 16 horizontal scanning lines for the B and E lines, and 8 horizontal scanning lines for the F line. Since the A line is for discriminating the non-image area, 4 horizontal scanning lines are required, and the B and E lines are for discriminating only the image area. Therefore, a wide range is required. The 16 horizontal scanning lines, F line are the non-image area and the caption signal. Therefore, 8 horizontal scanning lines are set. Needless to say, the number of horizontal scanning lines is not limited to this, and another number of horizontal scanning lines may be used, as long as the video signal can be discriminated by the number of horizontal scanning lines.

The number of samplings per horizontal scanning line is about N = 20 in FIG. 2 because sampling is performed at about 10 μS due to digital video signal processing.
The sampling method is such that the sampling clock of 10 μS is 1
The sampled video data of 4 points in the horizontal period is extracted, and 2 μm is extracted from each sampling point.
S shift 4 points, 4μS shift 4 points, 6
4 points with μS offset and 4 points with 8 μS offset are extracted, and images are compared from a total of 20 points. The number of sampling points may be 16, 32, 64 points, ...

A method of discriminating the data of the A line will be described.
FIG. 4 shows sampling for data discrimination. The horizontal axis represents one horizontal scanning line data sampling point, and the vertical axis represents the horizontal scanning line. In the figure, a is the first frame, b is the second frame, and c is 3
Frame, d is 4th frame, e is 5th frame, and f shows the distribution of sampling data when these frames are superposed.

First, data 1 and data 6 of the first horizontal scanning line are compared in the first frame. If they are the same, data 6
And data 11 are compared, and if they are the same, data 11 and data 16 are compared. And if they are the same,
The data 16 is compared with the data 2 of the second horizontal scanning line of the next frame, which is two frames. Hereinafter, if the same comparison is made, if the data is the same, the sequential comparison is continued, and the data 15 and the data 20 of 5 frames are compared. . That is, if the data is sampled over 5 frames as shown in FIG. 5F and all are the same, it is possible to determine that all the areas are the same.

This determination shows the operation of step S3 in the flowchart of FIG. Therefore, 20 pieces of data are extracted from 5 horizontal scanning lines out of 5 frames, and the same data is discriminated.

Next, a method of discriminating B line data and E line data will be described. FIG. 5 shows sampling for data discrimination. Normally, processing is performed with 20 sampling points in the horizontal direction, but in the figure, the array up to the 10th sampling point continues after the 10th sampling point, and therefore the description is omitted.

In the figure, a is the first frame, b is the second frame, c is the third frame, d is the fourth frame, e is the 13th frame, f is the 14th frame, g is the 15th frame,
h is the 16th frame. Also, from the 5th frame to 1
The second frame is omitted as it is shown as follows.

First, in the fifth frame, the (5 × n (n = 1, 2, 3, 4)) th video data of the fifth horizontal scanning line is extracted. Here, if the sixth frame or more is a G frame, and G / 5 = S is too much A, the G frame is (5 × n (n: 0, Four pieces of 1st, 2nd, 3) + A) th video data are extracted. That is, when the fifth data is read, the first data is returned to the first, and the data is extracted from the next frame and the next horizontal scanning line.

Then, as in the case of the A line, it is compared with the adjacent data, and if they are all the same, it can be determined that there is no signal in the center of the screen or there is no brightness conversion.

Further, the image data of the F line is discriminated by 8 horizontal scanning lines. Therefore, 40 pieces of video data are extracted from 8 frames, and the same determination is performed.

Next, a specific processing method will be described with reference to the flowchart of FIG.

Initialization is performed in step S1. By default, the number of video data in one horizontal scanning period: N,
The time during which the video data in one horizontal scanning period is scanned:
By setting T and the sampling period: t, the number of samplings performed in one horizontal scan: n = T / t, and the sampling step for extracting video data when performing sampling: S = N / n are determined.

Further, in the case of discriminating A line, 4 horizontal scanning lines, in the case of discriminating B to E lines, 16 horizontal scanning lines, in the case of discriminating F line, 8 horizontal scanning lines, B to E.
When the line is discriminated, it is set so that the video data of 8 horizontal scanning lines can be captured.

In step S2, the first frame is set, the horizontal scanning line is reset, and the sampling value is reset.

In step S3, the first horizontal scanning line is set and the first video data of the first horizontal scanning line of the first frame is fetched into the area DV as a comparison data value.

In step S4, the sampling value J
Is set to 1 and the next sampling position b is calculated.
Then, the b-th video data of the same horizontal scanning line of the same frame is taken into the area D (horizontal scanning line h, sampling position b) as a comparison data value. In this case, the sampling position b is 6, and the area D (h, b) = D (1,6).

In step S5, the image data of D (1,1) stored in the area DV is compared with the image data of this area D (1,6). In this comparison, for example, the video data is converted into a 6-bit digital signal, of which the upper 5 bits are
Moreover, the comparison is performed with a tolerance of ± 1. Then, if they are not determined to be the same, the process returns to step S2 and the same process is performed in the next frame (second frame).

However, if it is determined that they are the same, the process proceeds to step S6. In this step S6, this D (h, b) = D (1,6) is newly stored in the area DV.

In step S7, lines A, B to E
Value H set to different number of horizontal scanning lines for line and F line
The value obtained by subtracting 1 from (I) is compared with the sampling value J. If they are not the same, the process returns to step S4 and steps S4 to S7 are repeated. That is, the comparison in step S5 is D (1,1) and D
After comparing with (1,6), D (1,6) and D (1,1)
1), D (1, 11) and D (1, 16) are compared, and when the sampling value J = (H (I) -1) is reached (the four sampled video data are the same in one horizontal period). (If there is), go to step S8.

In step S8, the frame is set to advance one frame from the current frame so as to advance to the next frame.

In step S9, the current horizontal scanning line h and the set horizontal scanning line H (I) are compared, and if they are not equal, the process returns to step S3 to set the number of horizontal scanning lines to 1
The number is increased, and the processes of steps S3 to S9 are similarly performed.

Then, in this step S9, h = H (I)
If it is determined, it can be determined that the A line, the B to E lines, or the F line, which is currently determined, are all the same.

Therefore, according to the flow chart shown in FIG. 6, it can be determined whether or not the video data of the lines are the same, and steps S3, S5, S6, S9 and S of FIG.
11, S14 can be processed.

As a second embodiment, there is a method of making a judgment by a single horizontal scanning line extending over a plurality of frames.
This is to perform each discrimination line by one horizontal scanning line.

However, as compared with the first embodiment, since there is no area to be discriminated in the vertical direction, A as shown in FIG.
Although it is possible to make a determination with 6 lines from line F to line F, at least 2 lines are required for the upper and lower screens for determining a non-image area, and it is necessary to increase the number of determination lines.

In this case, in the flow chart of FIG. 6, the position of the horizontal scanning line may be kept constant until it is determined that the video data are all the same, and H (I) =
It may be set to S (= 5).

Specifically, four samplings of one horizontal scanning line are performed, and when the comparison is completed, the process proceeds to the next frame, and a point on the same horizontal scanning line which is shifted by 2 μS in the horizontal direction from the sampled point is sampled. And compare. Then, by repeating the processing for 5 frames, the data of one horizontal scanning line is extracted in total, and the presence / absence of an image can be discriminated.

As a third embodiment, M (integer of 3 or more)
There is a method of making a distinction by a plurality of horizontal scanning lines extending over a field.

In the first and second embodiments, the processing is performed for each frame, and the data of 5 frames are compared to determine the presence or absence of an image. However, in the third embodiment, the data is compared by sampling over the M feeds. Therefore, it is possible to prevent a malfunction that occurs when the presence or absence of an image is instantaneously determined, and it is possible to sample video data for a long period of time and use it to determine the presence or absence of an image. Automatically, the display mode is automatically switched, and the fluttering of the screen caused by the change of the display mode is eliminated.

Next, setting of subtitle display will be described.
When subtitles are displayed as shown in FIG. 7a, for example, 'JIMAKU' is displayed in the non-image area below the 3: 4 image.

However, the subtitle display section is not displayed all the time and is often a blank image.
Therefore, in the present invention, when the cinema mode is received, the non-image area discrimination means switches to the zoom mode and is displayed as shown in FIG.

Then, as shown in FIG. 7B, 'JIMAKU'
The display may extend beyond the 9:16 screen because the image is enlarged.

In order to solve this, the present invention utilizes the discrimination of the F line in FIG. 2 when switched to the zoom mode, detects the presence or absence of subtitles, and performs subtitle processing (displays subtitles on the screen). Is to do. That is, the state of the F line is detected after switching to the zoom mode. The detection method is as shown in the flowchart of FIG. If the F lines are not all at the same level, or if they are not at the same level as the video level when the zoom mode is set, it can be determined that the F lines include some signal, and there is caption. Can be judged.

The main CPU is determined by the presence / absence of subtitles.
A signal with a caption 7 is output from the aspect ratio discrimination / caption detection circuit 8.

Upon receiving this signal, the main CPU 7 outputs the control signal so that the vertical deflection speed is increased only in the non-image area where the caption is present because it is considered that the caption display portion is outside the screen in the zoom mode. To do.

The deflection circuit which receives the control signal deforms the sawtooth wave of vertical deflection only when deflecting the non-image area where the caption is present, and sharply changes the sawtooth wave to increase the deflection speed. There is a method of deforming the sawtooth wave, for example, by increasing the current for shaping the sawtooth wave by that position. There is also a method of increasing the charging / discharging speed of a charging / discharging circuit that generates a sawtooth wave.

As a result, as shown in FIG. 7c, the region including the lower subtitle display position is vertically compressed, and the subtitle can be displayed without protruding from the screen.

FIG. 8 is a specific example of aspect ratio discrimination / caption detection.

The luminance signal input to the input terminal 8a is DC cut by the capacitor, biased to a predetermined value by resistance division, and amplified by the transistor.

An LPF composed of a capacitor and a resistor
At, only the low frequency luminance signal is extracted and amplified by the transistor. The LPF 81 is configured by these, and only the low frequency band of the luminance signal is extracted.

The output of the LPF 81 is an IC for A / D conversion.
(For example, Sanyo Denki Co., Ltd .: LC7480) is input to pin 6.

On the other hand, the horizontal synchronizing pulse input to the input terminal 8b is an IC composed of an AND circuit (for example, SN7
4LS123) 2 of the clamp pulse generation circuit 83
The clamp pulse is input to the pin, the clamp pulse is output from the pin 5, and is input to the pin 12 of the A / D converter 82.

Here, the clamp pulse generating circuit 83 is set to 2
From the horizontal synchronizing pulse input to the pin, a pulse set by a time constant circuit composed of a resistor and a capacitor connected to pins 14 and 15 is output from pin 13 and re-input from pin 9. Then, the pulse set by the time constant circuit composed of the resistor and the capacitor connected to pins 6 and 7 is output from pin 5 as a clamp pulse. This clamp pulse coincides with the position of the pedestal level in the video signal, and the level at that position is used as the reference level.
It is used to perform the clamp in the / D converter 82.

The video signal clamped by the clamp pulse is A / D converted into a 6-bit digital luminance signal,
The higher-order bits are sequentially output from the terminals from pin 18 to pin 18.

The timing clock for A / D conversion is determined by the determination CPU 84 (for example, M3 manufactured by Mitsubishi Electric Corporation).
4225) is created by a program based on the oscillator OSC connected to pins 27 and 28 as an oscillator of 4225), and is output from pin 12. Then, it is input as a clock to pin 20 of the IC of the A / D converter 82. This clock serves as a timing pulse for fetching data.

In the 6-bit digital luminance signal, the upper 5 bits are 11, 10, 9, 8, 6 of the discrimination CPU 84.
The upper bits are input to the pins in order.

Then, the above-mentioned discrimination processing is carried out, and a discrimination signal of the presence / absence of subtitles is outputted from the 22nd pin and a discrimination signal of whether the screen is letterbox or not is outputted from the 16th pin. These discrimination signals are input to the main CPU 7 through the output terminals 8d and 8e, and the deflection circuit is processed according to the discrimination signals.

Pins 17 to 21 of the discrimination CPU 84 are terminals for setting discrimination conditions. This determination is preset as in the above-mentioned flowchart. However, the determination condition can be set by setting these 17 to 21 pins to H level or L level. In the embodiment, the number of frames or the number of fields is used, but the time may be set at this terminal.

Pin 17 is a terminal for selectively setting how much time image data is used for comparison / determination, and pin 18 is a terminal for selectively setting which horizontal scanning line is used as a reference.
Pin 19 is a terminal for selectively setting a brightness level for determining a non-image area, pin 20 is a second terminal for selectively setting how much time image data is used for comparison and determination, and pin 21 is for one horizontal scanning line. This is a pin to select and set how much sampling is performed during the period.

Here, the setting of time will be described. The longer the time required for the determination is, the more the malfunction can be prevented, but it takes time for the determination. Also, malfunctions are most likely to occur in broadcast programs and programs from other sources in which the brightness around the product in the video signal is reduced to emphasize the product, and commercials (also called CMs) showing the company name. There is).

Most commercials currently available have a duration of 15 seconds. Therefore, it is conceivable that the maximum time during which the same image is displayed in a commercial is considered to be about 4 seconds and used for setting this time.

Therefore, it is determined that the letterbox size or the subtitle is displayed if the discrimination time is set to about 4 seconds, and if the same luminance level is discriminated after this time is exceeded.

[0111]

According to the present invention, when a letter box type such as a cinema size in movies or video software is mixed even in a broadcast with an aspect ratio of 3: 4, the aspect ratio is 9:16.
In a television receiver having a CRT, the screen size of normal mode, zoom mode, etc. is automatically switched by judging the reception state on the display screen according to each source, and the user operation is performed. Can be eliminated.

Further, even a subtitle in the non-image area on the lower side of the letterbox can be detected by the television receiver without the user's adjustment, and the subtitle can be automatically displayed without overflowing the screen. Is possible.

[Brief description of drawings]

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

FIG. 2 is a diagram showing discrimination lines on the screen of the present invention.

FIG. 3 is a flowchart of screen discrimination / caption detection according to the present invention.

FIG. 4 shows the first sampling of the present invention.

FIG. 5 shows a second sampling of the present invention.

FIG. 6 is a flowchart of image discrimination according to the present invention.

FIG. 7 is an explanatory diagram of subtitle display according to the present invention.

FIG. 8 is a diagram showing a specific example of aspect ratio discrimination / caption detection of the present invention.

FIG. 9 is a diagram showing a display mode.

[Explanation of symbols]

 1a, b, c, d input terminal 2 selection switch 3 Y / C separation circuit 4 video chroma processing circuit 5 CRT drive circuit 6 CRT 7 main CPU 8 aspect discrimination / caption detection circuit 8a, b, c input terminal 8d, e output Terminal 81 Low-frequency pass filter (LPF) 82 A / D converter 83 Clamp pulse generation circuit 84 CPU for discrimination

Claims (4)

[Claims] 1. A television receiver for displaying an input video signal on a screen having an aspect ratio different from that of the video signal, wherein a video for detecting a low-frequency video signal in a plurality of areas provided on the screen. A signal detecting means, a video signal change detecting means for detecting a change in the low frequency video signal in the area, an image determining means for determining the presence or absence of an image by the output of the video signal change detecting means, and the image determining means. And a display adjusting means for changing the aspect ratio of the screen display of the video signal by the output of the video signal, the video signal having a non-image area where there is no image on a part of the screen is discriminated, and the non-image area A television receiver that displays on the screen in the screen display mode in which is displayed the least. 2. A television receiver for displaying an input video signal on a screen having an aspect ratio different from the aspect ratio of the video signal, and detecting a low frequency video signal in an area at least at two positions provided on the screen. Video signal detection means, video signal change detection means for detecting a change in the low frequency video signal in the area, image discrimination means for discriminating the presence or absence of an image by the output of the video signal change detection means, and the image discrimination Display adjustment means for changing the aspect ratio of the screen display of the video signal by the output of the means, and a non-image area discrimination means for discriminating a video signal having a non-image area where there is no image on a part of the screen; A television receiver comprising a caption discriminating means for discriminating a change in a video signal in a non-image area as a caption signal. 3. A television receiver for displaying an input video signal on a screen having an aspect ratio different from the aspect ratio of the video signal, for detecting low frequency video signals in at least two areas provided on the screen. Video signal detection means, video signal change detection means for detecting a change in the low frequency video signal in the area, image discrimination means for discriminating the presence or absence of an image by the output of the video signal change detection means, and the image discrimination Display adjustment means for changing the aspect ratio of the screen display of the video signal by the output of the means, and a non-image area discrimination means for discriminating a video signal having a non-image area where there is no image on a part of the screen; A screen including a caption discriminating means for discriminating a change in the video signal in the non-image region as a caption signal, and displaying the least image in the non-image region. A television receiver adapted to display in a display mode and to increase a scanning speed of a display position for displaying a subtitle by the output of the subtitle discriminating means. 4. A television receiver for displaying an input video signal on a screen having an aspect ratio different from the aspect ratio of the video signal, the low frequency video signal being detected in at least two areas provided on the screen. Video signal detection means, video signal change detection means for detecting a change in the low frequency video signal in the area, image discrimination means for discriminating the presence or absence of an image by the output of the video signal change detection means, and the image discrimination Display adjustment means for changing the aspect ratio of the screen display of the video signal by the output of the means, and a non-image area discrimination means for discriminating a video signal having a non-image area where there is no image on a part of the screen; A caption discriminating means for discriminating a change in the video signal in the non-image area as a caption signal, and discriminating times of the image discriminating means and the caption discriminating means respectively A television receiver characterized in that is shorter than the time of one program.