JP2008072300A - Image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display device being a hold type image display device using a backlight as a light source, which enables a user to recognize natural movements by resolving irregular movements in a 3:2 pull-down system and reduces blur caused by a retinal after-image effect due to user's eye's following when displaying a telecine-converted video image signal in the 3:2 pull-down system. <P>SOLUTION: The hold type image display device using a backlight 11 as the light source includes a means 8 which controls a turning-on/off pattern and period of the backlight at a frame rate different from a frame rate of image signal processing by a LSI and data write to a display device 7 without changing this frame rate when displaying the video image signal telecine-converted by the 3:2 pull-down system. The backlight is controlled so as to be extinguished for a prescribed time at the start and the end of an image held for three frames. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a video display device, and more particularly to a backlight blinking control method in a video display device.

3: 2 pull-down telecine conversion To display video from film sources shot at 24 frames per second, such as movies, on an NTSC TV receiver via package media such as TV broadcast, video tape, and DVD Needs to be converted into a video image signal of about 60 fields per second. This conversion is called telecine conversion by the 3: 2 pull-down method. The image of each frame on the film is captured as a digital image. . . The odd-numbered line image and the even-numbered line image are developed in the odd-numbered field and even-numbered field of the video image signal which is the interlaced scanning method.

  FIG. 1 illustrates telecine conversion by the 3: 2 pull-down method. In the figure, the frames of the film taken at a time interval of 1/24 seconds are arranged from the left side to the right side in the figure. In the 3: 2 pull-down method, the first frame located at the left end of the figure is assigned to two fields, and the second frame located on the right side is assigned to three fields. By repeating the assignment to the third and subsequent frames in two fields and three fields, a film of 24 frames / second can be converted into a video image signal of about 60 fields / second.

Film mode detection / display On the other hand, the TV receiver can handle and display the video image signal that has been telecine-converted by the 3: 2 pull-down method as described above in the same manner as an interlaced video signal by the normal NTSC method. It becomes.

  However, when the video display device is a progressive scanning type, the video scanning signal is more positively detected by detecting that the video video signal has been telecine converted by the 3: 2 pull-down method. Display is possible. This detection / display is called a film mode or a cinema mode.

  The lower part of FIG. 1 explains this display method. First, film mode detection is performed by comparing the video content of each field of the video video signal. As an example of this detection method, the video content of field E in FIG. 1 is always the same repeated field as the video content of field C, which is specific to video video signals that have been telecine converted by the 3: 2 pull-down method. Is. This presence is detected by calculating the sum of absolute differences of pixel values.

  In this way, when it is detected that the video signal has been telecine-converted by the 3: 2 pull-down method, the odd and even fields of the video image signal constituting the original film frame are specified. This can be reconstructed and displayed as a sequentially scanned image. In FIG. 1, the sequentially scanned image I is reconstructed using the odd field A and the even field B. The progressively scanned image II is also reconstructed using the odd field A and the even field B. That is, the sequentially scanned images I and II are the same. Further, using the odd field C (= E) and the even field D, the sequentially scanned images III to V are reconstructed, and these are the same. Here, the point to be noted in this explanation is that the car always moves from left to right at the position on the display screen in the original film frame, but the car is stopped and displayed between the sequential scanning displays I and II. The car is stopped and displayed even during the sequential scanning displays III to V.

On the other hand, when a scan image is sequentially generated by performing I / P (interlace / progressive) conversion as an interlaced video signal according to the normal NTSC system without detecting the film mode, the image of the upper and lower lines in the field is used. Since processing such as interpolating and generating lines that did not exist in the original video image signal is included, there is an adverse effect that the vertical resolution falls compared to the case of detecting and displaying the film mode. It is desirable to detect and display film mode.
JP 2005-117529 A

2. Problem of Displaying Video Video Signal that has been Telecine-Converted by 3: 2 Pull-down Method As described above, the video image signal that has been telecine-converted by 3: 2 pull-down method is detected and displayed in the film mode in FIG. Shows a state in which the horizontal axis is displayed on the display screen, and the vertical axis is displayed with time, focusing on the moving object in the video. A vertical band with a certain width moves horizontally from left to right at a constant speed. The vertical time interval is 1 frame = 1/60 second interval. In a hold-type video display device such as a liquid crystal panel, the display state during this time does not change. Further, in FIG. 2, 1 frame = 1/60 seconds in the same manner as the car is stopped between the sequential scanning displays I and II and the vehicle is stopped between the sequential scanning displays III to V as well. Image data is written and updated at intervals, but the object stops and is displayed between the first (i) and second (ii) frames from the top, and the third (iii) to fifth The object stops and is displayed between the frames of (v).

In addition to the problem that the basic motion interval is long at 24 frames / second, the problem is that the display is a problem compared to the case of displaying an interlaced video signal that is not subjected to normal telecine conversion. Exists.
The first is that the movements that were at equal time intervals in the original film frames have become irregular time intervals followed by a 2 frame: 3 frame pattern. This will be recognized as an unnatural motion that is not continuous (Problem 1).
Secondly, at the same time as the problem 1, motion blur due to the retinal afterimage effect due to the follow-up vision of the human eye in a hold-type video display device such as a liquid crystal panel becomes more prominent. This will be described next.

The motion blur due to the retinal afterimage effect in the hold-type image display device following the eye of the human eye. The above description relates to the video signal based on the 3: 2 pull-down method. The motion blur due to the retinal afterimage effect by the visual follow-up of the human eye in the video image signal will be described.

  FIG. 3 explains the movement and blur width of the video display by the 2: 2 pull-down method in the hold-type video display device. The telecine conversion by 2: 2 pull-down method is the same as the case of 3: 2 pull-down method in that telecine conversion is performed in order to display a film source shot at 24 frames per second such as a movie on a TV receiver. One method is different from the other in that it is converted into a video image signal of 50 fields per second in order to display an image on a PAL or SECAM TV receiver. It is always a conversion from one frame of film to two fields, and it is displayed in a pattern of 2 frames: 2 frames. Unlike the case of 3: 2 pull-down method, it moves with equal time intervals as shown in the figure. is there.

  It is known that the retinal afterimage effect of the human eye on a moving object is recognized by integrating the image following the movement. In FIG. 3, as shown in “appearance by following vision” in the figure, a blur having a width in the contour portion occurs. This blur width becomes larger as the video hold time is longer. In the case of a normal PAL or SECAM interlaced video signal, there is a motion at an interval of 50 fields / second. Compared with this, a video video signal that has been telecine converted by the 2: 2 pull-down method is twice as large. A blur of width has occurred.

  The above is about motion blur due to the retinal afterimage effect of the human eye following the video signal that has been telecine-converted by the 2: 2 pull-down method. The same applies to the motion blur in the case of the 3: 2 pull-down method. Considering this, a blur having a width at the contour portion as shown in “appearance by following vision” in FIG. 2 occurs. However, this blur width is an irregular pattern of 2 frames: 3 frames, so that there is a problem that the blur width is larger than that of the 2: 2 pull-down method (problem). 2).

New known technique for solving the problem Further, as a known technique for solving the above-mentioned problem, there is a frame rate conversion processing technique. Patent Document 1 describes a technique for generating a frame image necessary for this by performing motion vector detection with a frame rate higher than about 60 Hz of the NTSC system.

  The frame rate is often required to be constant due to system restrictions in the display device, and is the minimum that can ideally support both the video signal that has been telecine converted by the 3: 2 pull-down method and the interlaced video signal by the normal NTSC method. The frame rate is about 120 Hz, which is the least common multiple of 24 Hz and about 60 Hz, and FIG. 4 shows the display state of the frame rate conversion processing when operating at 120 Hz. As shown in the figure showing the movement of the position of the object and the blur width, the 3: 2 irregular movement (problem 1) and the blurring of the human eye following (problem 2) are sufficiently solved by this technology. Can be done.

  Furthermore, the basic problem that the interval between film movements is 24 frames / second, which is longer than the normal NTSC format interlaced video signal, and makes it possible to recognize jerky movements can be solved. Is possible.

  However, as an adverse effect at this time, in FIG. 4, the image of the frame (other than i and iii) painted with diagonal lines is the image generated by predicting the motion vector from the frame (i and iii) not painted with the previous diagonal lines. And many generation errors are included. As shown in the figure, since the shaded frame includes 80% of the entire frame, there is a possibility that the image display has a very large number of generation errors (Problem 3).

In addition, to double the frame rate from about 120 Hz to about 60 Hz, it is necessary to perform back-end video signal processing including image quality correction and display data writing to the display device at twice the speed. Yes, and appropriate video processing performance is required (Problem 4).
Furthermore, the power consumption for this process also increases (Problem 5).

  In order to solve the above problems, the video display device according to the first aspect of the present invention sets the frame rate of video signal processing by LSI and data writing to the display device when displaying video video signals telecine-converted by the 3: 2 pull-down method. Without changing, there is provided means for controlling the blinking pattern and cycle of the backlight at a frame rate different from the frame rate.

  The video display device according to the second aspect of the invention controls the backlight to be turned off for a predetermined time at the beginning and end of an image held for three frames in the first aspect of the invention.

  In the third aspect of the invention, without changing the frame rate of data writing to the display device, the frame generation means based on the video signal processing by the LSI such as the film de-judging processing is used together, and the blinking pattern and cycle of the backlight Is controlled at a frame rate different from the frame rate.

  Furthermore, the video display device according to the fourth aspect of the present invention detects a motion vector from the preceding and following frames in the third aspect of the present invention to generate an intermediate time frame, and the original frame image does not move continuously. While the frame image data is written in the display device, the backlight is turned off.

When displaying a video signal that has been telecine converted by the 3: 2 pull-down method,
According to the video display devices according to the first and second aspects of the present invention, a slight luminance flicker phenomenon and an improvement in the maximum luminance of the backlight are required as compared with the case where only the conventional film mode display is performed. Without changing the video signal processing by LSI and writing display data to the display device at all, it can be recognized as a natural movement by eliminating the irregular movement of 3: 2, and further by tracking the human eye The blur width is improved.

  Further, according to the video display devices according to the present invention 3 and 4, the luminance flicker phenomenon as seen in the progressive scanning impulse video display device and the improvement of the maximum luminance of the backlight are required. Compared with the film dejaddling process, all frames of the original film can be displayed, so the rate of newly generating frames can be minimized and high-definition images with fewer generation errors can be left. In addition, it can be recognized as a natural movement by eliminating the irregular movement of 3: 2 as in the case of the de-juddering process, and further follow the human eye more than when the de-juddering process is performed. The blur width by vision is greatly improved. In addition, compared with the case where frame rate conversion processing to 120 Hz or the like is performed, it is not necessary to increase the frame rate of video signal processing by LSI and writing display data to the display device, so image processing performance and consumption for that amount High-definition video with few generation errors can be left without requiring power and by minimizing the rate at which new frames are generated, and then the same as when performing the frame rate conversion process. In addition, it is possible to recognize a natural movement by eliminating the irregular movement of 3: 2, and the blur width due to the tracking of human eyes is greatly improved more than when the frame rate conversion process is performed.

The best mode for carrying out the present invention will be described.
Embodiments of a video display apparatus according to the present invention will be described with reference to the drawings.

  Example 1 will be described. FIG. 5 is a block diagram schematically showing a video display apparatus according to the first embodiment of the present invention. From the left end of the figure, an interlaced video signal separated into luminance / chrominance components is input through a video signal processing circuit (not shown). First, in the film mode detection circuit 1, whether or not the input video signal is a video signal telecine-converted by the 3: 2 pull-down method is determined by a method of paying attention to the field repeatedly as described above. Detected. In the case of a normal NTSC interlaced video signal, the other field video that is input to the motion adaptive type or motion compensation type I / P conversion circuit 3 and is not included in the original video signal is displayed on the upper and lower lines or front and rear. It is generated with reference to the field video and is converted into a progressive scanning (progressive) video signal. However, when the film mode detection circuit 1 detects that the video signal has been telecine converted by the 3: 2 pull-down method, the video signal is not input to the I / P conversion circuit 3. Are switched by the signal switching circuit 2 and input to the film mode restoration circuit 4. The film mode restoration circuit 4 refers to the frame discrimination information (information on which target field is A to E in FIG. 1) input from the film mode detection circuit 1, and as shown in the lower part of FIG. The fields are combined and converted to a progressive scanning (progressive) video signal. The progressive scanning video signal converted by any one of the circuits further passes through the enlargement / reduction / image quality correction circuit 5 and the timing controller 6, and is finally written on the liquid crystal panel 7 in order from the uppermost line. The above is the processing flow of the video signal. On the other hand, for the control of the backlight 11, in this embodiment, the backlight blinking pattern generation circuit 8 exists and the film mode output from the film mode detection circuit 1 is present. A switching signal and frame discrimination information are input. Based on the flashing pattern generated in the backlight flashing pattern generation circuit 8, the backlight vertical split flashing control circuit 9 controls the inverter 10 in synchronization with the input vertical synchronization signal, and is composed of a cold cathode fluorescent tube or the like. FIG. 6 is an explanatory diagram of the backlight blinking control method according to this embodiment performed by these circuits.

  The top row in FIG. 6 shows a vertical scanning method in which scanned image data is written and updated sequentially on the liquid crystal panel. One block shows image writing and holding display for one frame. The image is updated sequentially from the first line of the liquid crystal panel, and the final N line is updated after 1/60 seconds. The updated image is held for 1/60 second.

  Next, the middle part of FIG. 6 shows a backlight blinking control method. The shaded area is in the on state, and the black area is in the off state. This backlight blinking control is also changed in order from the first line to the last line. The vertical control speed is controlled at 1/60 second, which is the same as the above-described renewal of the liquid crystal panel, but the ON / OFF holding period can be freely controlled. It is held for 30 seconds, and is held for 1/120 seconds when it is turned off. Flashing control with a period of 1/24 seconds is performed in the pattern.

  Further, FIG. 7 shows a lighting state of the backlight in the two-dimensional space at the time point A in FIG. In FIG. 7, dozens of cold cathode fluorescent tubes arranged in the horizontal direction are arranged in the vertical direction, and the cold cathode fluorescent tubes in the middle portion in the vertical direction are turned off. Only the number of cold cathode fluorescent tubes arranged in the vertical direction can divide the vertical region and control lighting. Similar control is possible even in the case of an LED other than a cold cathode fluorescent tube as an element constituting the backlight.

  Further, the lowermost part of FIG. 6 shows how the liquid crystal panel and the backlight are viewed together as a final display.

  Light from the backlight, which is a light source, is transmitted at a ratio according to the alignment state of the liquid crystal of the liquid crystal panel, and finally reaches a human eye. No matter what image is set on the liquid crystal panel, the display is black and does not reach the human eye in the area where the backlight is turned off.

  FIG. 8 is an explanatory diagram showing how the display corresponding to FIG. 2 changes when the display by the backlight blinking control of FIG. 6 is performed.

  In FIG. 2, the first 1/120 second and the last 1/120 second of the image held for three frames are not displayed because the backlight is turned off. For this reason, a difference in recognition of human eyes, which will be described next, occurs.

  First, as an unfavorable point in terms of the performance of the video display device of the present embodiment, it is perceived that the brightness of the display is steadily darkened by human eyes at a ratio of the period during which these backlights are turned off. Sometimes. In this case, it is recognized that the luminance is changed to 80% as compared with the case where the backlight is not turned off at all. In order to compensate for this decrease in luminance, it is necessary to increase the maximum luminance of the backlight accordingly. However, power consumption does not increase before and after the change of the backlight control method. In addition, since the luminance changes in a short cycle, it may be recognized as flicker of the entire screen. However, conventional CRT video display devices perform impulse-type display in which a moment during 1/60 seconds is illuminated with a large amount of light and the remaining period is off, and similar flicker occurs. It was. Further, as a method of reducing the flicker, it is possible to shorten the luminance change cycle by turning off the backlight in the period a in FIG.

  Next, as a good point of the performance of the video display device of the present embodiment, in FIG. 2, the movement of an irregular time interval followed by a pattern of 2 frames: 3 frames is shown, but in FIG. : It is improved to the movement of the same time interval in the pattern of 2 frames. This is recognized as a continuous and natural movement (solving problem 1).

  Next, with regard to the motion blur due to the retinal afterimage effect due to the follow-up vision of the human eye, the blur width is improved as shown in “Appearance by follow-up vision” in the figure. This is an improvement over the blur width shown in “appearance by following vision” in the case of 2: 2 pull-down in FIG. 3 (solving problem 2).

  A second embodiment will be described. FIG. 10 is a block diagram schematically showing a video display apparatus according to the second embodiment of the present invention. From FIG. 5 of the first embodiment, a film de-juddering processing circuit 12 is added. Further, the backlight blinking pattern generation circuit 8 ′ is compatible with the film de-daggering process and is different from that of FIG. 5.

  The present embodiment is combined with a film de-judder processing technique, and a method for controlling the backlight blinking will be described. FIG. 9 shows a display by the film dejaddling process. The film de-judder processing technology, although the frame rate remains at 60 Hz, the motion vector detection is performed for the motion of 24 Hz of the original film frame only during the film mode detection / display, and the frame image is generated. This is a technique for converting to an image having a motion of 60 Hz, which is the same as an interlaced video signal by the NTSC system.

  As shown in FIG. 9, the anomalous movement of 3: 2 is resolved (solving problem 1) and the blur width is improved by following the eyes of the human eye (improving problem 2). As shown in the third frame, in order to make the movements at equal intervals, one of the two images of the original film frame is not used for display as it is. Is detected and used only to generate a frame of motion in between. This is because the predicted and generated video is displayed instead of the original film frame video, and it is considered that the video contains a lot of generation errors (problem 6). .

  FIG. 11 is an explanatory diagram of the film de-juddering process and the backlight blinking control method according to the second embodiment. A frame painted with diagonal lines is an intermediate time frame generated by detecting a motion vector from the preceding and following frames (i, iii frames). The x-marked frame in the figure is an image of the original film frame that does not move continuously, but as shown in the middle of the figure, the backlight is turned off during this period. It is not a display that reaches the human eye. The backlight is controlled to blink with a period of 1/48 seconds with a pattern of lighting of 1/240 seconds and extinguishing of 1/60 seconds, and the time-averaged luminance becomes 20% compared to when 100% is turned on. In the same manner as described above, there is a possibility that the screen is recognized as flicker. However, since all the images of the original film frames are used for display, it is possible to minimize the ratio of the frame generation error during the motion vector detection to the total display (solving problem 6). .

  FIG. 12 shows the movement of the video display and the blur width due to the following eye of the human eye when the film de-juddering process and the backlight blinking control of FIG. 11 are performed. It is a drastic improvement in the blur width (improvement of Problem 2) by eliminating the anomalous movement of 3: 2 (solving Problem 1) and following the eyes of the human eye. In the display of the interlaced video signal by the normal NTSC system, it is considered that pseudo-impulse display is performed in order to eliminate the retinal afterimage effect due to the follow-up vision of the human eye in the hold-type video display device. In the case of displaying a video signal subjected to telecine conversion by the 2-pull-down method, it is shown that the same display can be performed by effectively controlling the blinking of the backlight in this way.

  Compared with the case where the frame rate conversion process of FIG. 4 is performed, in the control according to the present embodiment, the frame rate of the video signal processing and the display data writing to the display device remains 60 Hz. There is no need for processing performance or power consumption (solving problems 4 and 5).

  Further, in the frame rate conversion process, five times as many frames as the original film frame are generated by motion vector detection. However, when the frame rate conversion process is combined with the backlight blinking control, it is doubled. It is only necessary to newly generate a number of frames. By minimizing the frame generation rate, it is possible to display a high-definition video with few generation errors (improvement of Problem 3).

It is explanatory drawing of the telecine conversion by 3: 2 pull-down system. It is explanatory drawing of the motion of a video display by 3: 2 pull-down system, and a blur width. It is explanatory drawing of the motion of a video display by 2: 2 pull-down system, and a blur width. It is explanatory drawing of the display motion by the frame rate conversion process to 120 Hz of the image | video by 3: 2 pull-down system, and a blur width. 1 is a block diagram schematically showing a video display device of Example 1. FIG. It is explanatory drawing of the backlight blink control method in Example 1. FIG. It is a figure which shows the backlight apparatus and lighting state of A time point in the figure of FIG. It is explanatory drawing of the motion of a video display in Example 1, and a blur width. It is explanatory drawing of the movement of display and blur width by a film dejaddling process. It is a block diagram which shows roughly the video display apparatus of Example 2. FIG. It is explanatory drawing of the film dejaddling process in Example 2, and a backlight blink control method. It is explanatory drawing of the motion of a video display in Example 2, and a blur width.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Film mode detection circuit 2 Signal switching circuit 3 Motion adaptive type / motion compensation type I / P conversion circuit 4 Film mode restoration circuit 5 Enlarging / reducing / image quality correction circuit 6 Timing controller 7 Liquid crystal panel 8 Backlight blinking pattern generation circuit 8 ′ Backlight flashing pattern generation circuit (supports film dejaddling)
9 Backlight vertical division flashing control circuit 10 Inverter 11 Backlight 12 Film de-juddering processing circuit

Claims (4)

In a hold-type video display device using a backlight as a light source,
When displaying a video image signal that has been telecine-converted by the 3: 2 pull-down method, the flashing pattern and cycle of the backlight are changed to the frame without changing the frame rate of image signal processing by LSI and data writing to the display device. An image display device comprising means for controlling at a frame rate different from the rate. The video display device according to claim 1,
A video display device, wherein the backlight is turned off for a predetermined time at the beginning and end of an image held for three frames. In a hold-type video display device using a backlight as a light source,
When displaying video video signals telecine-converted by 3: 2 pull-down method, frame generation means by video signal processing by LSI such as film de-juddering processing is used without changing the data writing frame rate to the display device And a means for controlling the blinking pattern and cycle of the backlight at a frame rate different from the frame rate. The video display device according to claim 3.
A motion vector is detected from the previous and next frames to generate an intermediate time frame, and the backlight is turned on while the original frame image data is written to the display device. A video display device which is controlled to be turned off.