JP2009258269A - Image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce image quality degradation due to image breaking, while maintaining an effect of a frame rate converter (FRC), when an image fails, in an image display device with a motion compensation type FRC function. <P>SOLUTION: A liquid crystal display device comprises: an FRC section 10 which converts the number of frames or the number of fields of an input image signal and outputs it to a liquid crystal display panel 16, by interpolating the image signal on which motion compensation processing is performed between frames or fields of the input image signal; and a motion vector detection section 11e for estimating an image failure degree of an interpolation image signal which is interpolated between frames or fields of the input image signal. When it is presumed that the interpolation image of the interpolation image signal fails by the motion vector detection section 11e, a brightness level of the interpolation image signal is made lower than the brightness level of the input image signal by the FRC section 10. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image display device, and more particularly to an image display device having a function of converting a frame rate or a field rate.

  In contrast to the cathode ray tube (CRT), which has been mainly used for the purpose of embodying moving images, the LCD (Liquid Crystal Display) moves the viewer when moving images are displayed. There is a so-called motion blur defect in which the outline of a part is blurred and perceived. It has been pointed out that this motion blur is caused by the LCD display method itself (see, for example, Patent Document 1).

  In a CRT that performs display by scanning an electron beam to emit light from a phosphor, the light emission of each pixel is substantially in an impulse shape although there is some afterglow of the phosphor. This is called an impulse type display system. On the other hand, in the LCD, the charge stored by applying an electric field to the liquid crystal is held at a relatively high rate until the next electric field is applied. In particular, in the case of the TFT method, a TFT switch is provided for each dot constituting a pixel, and an auxiliary capacitor is usually provided for each pixel, and the ability to hold stored charges is extremely high. For this reason, light emission continues until the pixel is rewritten by applying an electric field based on image information of the next frame or field (hereinafter referred to as a frame). This is called a hold type display method.

  In the hold-type display method as described above, the impulse response of the image display light has a temporal spread, so that the time frequency characteristic is deteriorated, and the spatial frequency characteristic is accordingly lowered, resulting in motion blur. In other words, since the human line of sight smoothly follows a moving object, if the light emission time is long as in the hold type, the movement of the image becomes jerky due to the time integration effect and looks unnatural.

  In order to improve motion blur in the hold-type display method, a technique for converting a frame rate (number of frames) by interpolating an image between frames is known. This technique is called FRC (Frame Rate Converter) and is put into practical use in liquid crystal display devices and the like.

  Conventionally, as a method of converting the frame rate, various methods such as simply repeatedly reading the same frame twice or frame interpolation by linear interpolation between frames are known. However, in the case of frame interpolation processing by linear interpolation, unnatural motion (jerkiness, judder) associated with frame rate conversion occurs, so that the image quality is insufficient.

  Therefore, in order to eliminate the influence of the jerkiness and improve the moving image quality, motion compensation type frame interpolation processing using motion vectors has been proposed. According to this motion compensation process, since the moving image itself is captured and corrected, it is possible to obtain a very natural moving image without degradation in resolution and without occurrence of jerkiness. Furthermore, since the interpolated image signal is formed by motion compensation, it is possible to sufficiently improve the motion blur interference caused by the hold type display method described above.

  Patent Document 1 described above discloses a technique for improving a decrease in spatial frequency characteristics that causes motion blur by increasing a frame frequency of a display image by generating an interpolation frame adaptively in motion. ing. In this method, at least one interpolated image signal to be interpolated between frames of a display image is formed in a motion adaptive manner from the preceding and following frames, and the formed interpolated image signal is interpolated between frames and sequentially displayed. ing.

  FIG. 6 is a block diagram showing a schematic configuration of an FRC drive display circuit in a conventional liquid crystal display device. In the figure, the FRC drive display circuit interpolates an image signal subjected to motion compensation processing between frames of an input image signal. By doing so, the FRC unit 100 that converts the number of frames of the input image signal, and the electrode driving unit 103 for driving the scan electrodes and the data electrodes of the liquid crystal display panel 104 based on the image signal whose frame rate has been converted by the FRC unit 100 And an active matrix liquid crystal display panel 104 having a liquid crystal layer and electrodes for applying scanning signals and data signals to the liquid crystal layer.

  The FRC unit 100 includes a motion vector detection unit 101 that detects motion vector information from an input image signal, and an interpolation frame generation unit 102 that generates an interpolation frame from the motion vector information obtained by the motion vector detection unit 101. .

  In the above configuration, the motion vector detection unit 101 may obtain the motion vector information using, for example, a block matching method or a gradient method described later, or the motion vector information is included in some form in the input image signal. If this is the case, this may be used. For example, image data compression-encoded using the MPEG method includes motion vector information of a moving image calculated at the time of encoding, and the motion vector information may be acquired.

  FIG. 7 is a diagram for explaining frame rate conversion processing by the conventional FRC drive display circuit shown in FIG. The FRC unit 100 generates an interpolated frame (an image colored in gray in the figure) by motion compensation using the motion vector information output from the motion vector detecting unit 101, and the generated interpolation By sequentially outputting the frame signal together with the input frame signal, processing for converting the frame rate of the input image signal from, for example, 60 frames per second (60 Hz) to 120 frames per second (120 Hz) is performed.

  FIG. 8 is a diagram for explaining the interpolation frame generation processing by the motion vector detection unit 101 and the interpolation frame generation unit 102. The motion vector detection unit 101 detects the motion vector 105 from the frame # 1 and the frame # 2 shown in FIG. That is, the motion vector detection unit 101 obtains the motion vector 105 by measuring how much and in which direction the frame # 1 and frame # 2 have moved in 1/60 second. Next, the interpolation frame generation unit 102 allocates the interpolation vector 106 between the frame # 1 and the frame # 2 using the obtained motion vector 105. An interpolation frame 107 is generated by moving the object (in this case, an automobile) from the position of frame # 1 to a position after 1/120 second based on the interpolation vector 106.

  In this way, motion compensation frame interpolation processing is performed using motion vector information, and the display frame frequency is increased to change the display state of the LCD (hold type display method) to the display state of the CRT (impulse type display method). It is possible to improve the image quality degradation due to motion blur that occurs when displaying a moving image.

  Here, in the motion compensation frame interpolation process, detection of a motion vector is indispensable for motion compensation. As typical techniques for this motion vector detection, for example, a block matching method, a gradient method, and the like have been proposed. In the gradient method, a motion vector is detected for each pixel or small block between two consecutive frames, thereby interpolating each pixel or each small block of the interpolation frame between the two frames. That is, the number of frames is converted by correctly correcting and interpolating an image at an arbitrary position between two frames.

  In such motion-compensated FRC processing, the interpolated image may be easily broken depending on the content and state of the video. For example, when there is OSD display, when the S / N of the video is bad, or when the reproduced video is special. In such a case, it is common to turn off the FRC, but suddenly switching from on to off has a large change in appearance, and the viewer often feels uncomfortable.

  On the other hand, Patent Document 2 describes a method of inserting a black image in a non-video signal period within a frame period for the purpose of improving the dynamic reaction speed of a moving image, as described above. Patent Documents 3 and 4 describe a method of inserting the same image as the original image darkly (with reduced brightness) between frames.

The method for inserting the same frame will be described with reference to FIG. In the example shown in FIG. 9, the same frame i1 as the input frame f1 is darkened and inserted between the input frames f1 and f2 included in the input image signal, and the same frame i2 as the input frame f2 is darkened between the input frames f2 and f3. Is inserted. In this way, by inserting the same frame as the input frame between the input frames at a reduced luminance, the dynamic reaction speed can be improved while suppressing a decrease in the maximum luminance.
Japanese Patent No. 3295437 JP 2003-295156 A JP 2005-173573 A JP 2006-178488 A

  However, the inventions described in Patent Documents 2 to 4 improve the dynamic reaction speed by inserting a black image or a dark (decreased brightness) image between input frames. It does not correspond to image corruption caused by processing.

  In the case of the inventions described in Patent Documents 3 and 4, the luminance difference between the inserted image and the input frame (original image) increases as the luminance of the image inserted between the input frames decreases (darkens). Although the reaction speed becomes faster, since the same image as the original image is inserted between the input frames of the original image, not the interpolated image subjected to the motion compensation process, the effect of FRC by motion compensation can be obtained. The image quality deterioration due to the motion blur that occurs when displaying a moving image cannot be sufficiently improved.

  The present invention has been made in view of the above circumstances, and in an image display device having a motion compensation type FRC function, image quality deterioration due to image failure is reduced while maintaining the effect of FRC at the time of image failure. The purpose.

  In order to solve the above problem, the first technical means of the present invention interpolates an image signal subjected to motion compensation processing between frames or fields of an input image signal, so that a frame of the input image signal is obtained. An image display device comprising rate conversion means for converting the number or the number of fields and outputting to the display panel, the degree of image failure of the interpolated image signal inserted between frames or fields of the input image signal An image failure estimation means for estimating, and when the image failure estimation means estimates that the interpolated image of the interpolated image signal has failed, the rate conversion means determines the brightness level of the interpolated image signal as the input image. It is characterized by being lower than the luminance level of the signal.

  According to a second technical means, in the first technical means, the rate conversion means changes a luminance level of the input image signal and the interpolated image signal according to a degree of failure of the interpolated image. It is a feature.

  When the first technical means estimates that the interpolated image is broken in the first technical means or the second technical means, the third technical means performs the input image signal with respect to a reference luminance level preset in the image display device. The luminance level of the input image signal and the interpolated image signal are controlled so that the average luminance level of the input image signal and the interpolated image signal becomes the reference luminance level. Is.

  A fourth technical means is the first technical means according to any one of the first to third technical means, wherein the image failure estimation means is based on the number of motion vector candidates in the rate conversion means, and the image failure of the interpolated image signal. It is characterized by estimating the degree of.

  A fifth technical means is the first technical means according to any one of the first to third technical means, wherein the image corruption estimating means is based on a vector allocation state to the interpolated image in the rate converting means. It is characterized by estimating the degree of image failure.

  A sixth technical means is the first technical means according to any one of the first to third technical means, wherein the image failure estimation means is based on the number of motion vector intersections in the rate conversion means. It is characterized by estimating the degree of.

  A seventh technical means is any one of the first to sixth technical means, wherein the rate converting means detects motion vector information between consecutive frames or fields included in the input image signal. A detection unit; an interpolation vector allocating unit that allocates an interpolation vector between the frames or between the fields based on the detected motion vector information; and an interpolation that generates an interpolation image signal from the allocated interpolation vector. An image generation unit and an image interpolation unit for interpolating the generated interpolated image signal between the frames or between the fields are characterized.

  According to the present invention, in an image display device having a motion compensation type FRC function, the image quality due to image failure is maintained while maintaining the effect of FRC by reducing the brightness of the interpolated image while the FRC is turned on at the time of image failure. Deterioration can be reduced.

  Hereinafter, preferred embodiments of an image display device of the present invention will be described with reference to the accompanying drawings. Although the present invention can be applied to any of a field signal, an interpolated field signal, a frame signal, and an interpolated frame signal, both (field and frame) are in a similar relationship with each other, so A signal and an interpolated frame signal will be described as representative examples.

  FIG. 1 is a block diagram illustrating a configuration example of a motion compensated frame rate conversion unit included in the image display apparatus of the present invention. In the figure, reference numeral 10 denotes a frame rate conversion unit (hereinafter referred to as FRC unit), which corresponds to the rate conversion means of the present invention and detects a motion vector between two consecutive frames included in an input image signal. And a frame generation unit 12 that generates an interpolation frame (interpolated image) based on the detected motion vector. In addition, although the vector detection part 11 shows about the example at the time of using an iterative gradient method for a motion vector detection, it is not limited to this iterative gradient method, A block matching method etc. may be used.

  Here, the feature of the iterative gradient method is that a motion vector can be detected in units of blocks, so that several types of motion amounts can be detected, and a motion vector can be detected even in a small-sized moving object. Also, the circuit configuration can be realized on a small scale as compared with other methods (block matching method or the like). In this iterative gradient method, a method is used in which the gradient method is repeated for the detected block, using the motion vector of a nearby block that has already been detected as an initial displacement vector, and starting from this. According to this method, it is possible to obtain an almost accurate motion amount by repeating the gradient method about twice.

  In FIG. 1, a vector detection unit 11 limits a high frequency band by multiplying an extracted Y signal by LPF and a luminance signal extraction unit 11a that extracts a luminance signal (Y signal) from an input image signal (RGB signal). A preprocessing filter 11b for performing the motion detection, a frame memory 11c for motion detection, an initial vector memory 11d for storing initial vector candidates, and a motion vector detection unit 11e for detecting a motion vector between frames using an iterative gradient method. And an interpolation vector evaluation unit 11f that allocates an interpolation vector between frames based on the detected motion vector.

  The FRC unit 10 corresponds to the rate conversion means of the present invention, the motion vector detection unit 11e corresponds to the motion vector detection unit of the present invention, and the interpolation vector evaluation unit 11f corresponds to the interpolation vector allocation unit of the present invention. To do.

  Since the calculation of the iterative gradient method uses the differential component of the pixel, it is easily affected by noise, and the calculation error increases if the amount of change in the gradient in the detection block is large. To limit the high-frequency band. In the initial vector memory 11d, motion vectors (initial vector candidates) already detected in the previous frame are stored as initial vector candidates.

  The motion vector detection unit 11e selects a motion vector closest to the motion vector of the detected block from among the initial vector candidates stored in the initial vector memory 11d as an initial vector. That is, the initial vector is selected by the block matching method from the already detected motion vectors (initial vector candidates) in the blocks near the detected block. Then, the motion vector detection unit 11e detects a motion vector between the previous frame and the current frame by gradient method calculation with the selected initial vector as a starting point.

  The interpolation vector evaluation unit 11f evaluates the motion vector detected by the motion vector detection unit 11e, assigns an optimal interpolation vector to the inter-frame interpolation block based on the evaluation result, and sends the interpolated block to the frame generation unit 12. Output.

  The frame generation unit 12 includes an interpolation frame memory 12a for accumulating two input frames (previous frame and current frame), two input frames from the interpolation frame memory 12a, and an interpolation vector evaluation unit 11f. An interpolation frame generation unit 12b for generating an interpolation frame based on the interpolation vector of time, a time base conversion frame memory 12c for storing input frames (previous frame, current frame), and a time base conversion frame And a time base conversion unit 12d that inserts the interpolation frame from the interpolation frame generation unit 12b into the input frame from the memory 12c.

  The interpolation frame generation unit 12b corresponds to the interpolation image generation unit of the present invention, and the time base conversion unit 12d corresponds to the image interpolation unit of the present invention.

  FIG. 2 is a diagram for explaining an example of the interpolation frame generation process by the frame generation unit 12. The interpolation frame generation unit 12b extends the interpolation vector V assigned to the interpolation block to the previous frame and the current frame, and interpolates each pixel in the interpolation block using pixels near the intersection with each frame. . For example, in the previous frame, the luminance of point A is calculated from three points in the vicinity. In the current frame, the luminance of point B is calculated from the three neighboring points. In the interpolated frame, the luminance at point P is interpolated from the luminance at points A and B. The brightness at point P may be the average of the brightness at point A and the brightness at point B, for example.

  The interpolated frame generated as described above is sent to the time base converter 12d. The time base conversion unit 12d performs a process of converting the frame rate by inserting an interpolation frame between the previous frame and the current frame. As described above, the FRC unit 10 can convert the input image signal (60 frames / second) into the motion compensated output image signal (120 frames / second), and outputs this to the display panel, thereby reducing motion blur. It is possible to reduce and improve the video quality. Here, a case where the frame rate conversion of an input image signal of 60 frames / second to an output image signal of 120 frames / second is described, but for example, output image signals of 90 frames / second and 180 frames / second are obtained. Needless to say, it may be applied to a case.

  The image display device of the present invention includes the FRC unit 10 shown in FIG. 1 and aims to reduce image quality degradation due to image failure while maintaining the effect of FRC when the image is broken. The present invention can be applied to all image display devices having hold-type display characteristics such as a liquid crystal display, an organic EL display, and an electrophoretic display. In the following embodiments, a liquid crystal display panel is used as the display panel. A case where the present invention is applied to the liquid crystal display device used will be described as a representative example.

  FIG. 3 is a block diagram illustrating a configuration example of a main part of a liquid crystal display device according to an embodiment of the present invention. In the drawing, the liquid crystal display device includes an FRC unit 10, an image processing unit 13, a control unit 14, an electrode driving unit 15, and a liquid crystal display panel 16. The FRC unit 10, the image processing unit 13, the electrode driving unit 15, and the liquid crystal display panel 16 are connected to the control unit 14 and operate according to instructions from the control unit 14.

  In FIG. 3, only the motion vector detection unit 11e, the interpolation vector evaluation unit 11f, the interpolation frame generation unit 12b, and the time base conversion unit 12d in the FRC unit 10 are illustrated as main components, and other configurations of the FRC unit 10 are illustrated. The description of elements is omitted.

The image processing unit 13 is provided before the FRC unit 10, performs various image processes on the input image signal, and outputs the processed image to the FRC unit 10.
The electrode drive unit 15 is a display driver for driving the scan electrodes and data electrodes of the liquid crystal display panel 16 based on the image signal whose frame rate is converted by the FRC unit 10.
The liquid crystal display panel 16 is an active matrix liquid crystal display having a liquid crystal layer and electrodes for applying scanning signals and data signals to the liquid crystal layer.
The control unit 14 includes a CPU for controlling the above-described units, and controls the FRC process in the FRC unit 10.

  The motion vector detection unit 11e according to the present embodiment corresponds to the image failure estimation means of the present invention, and the failure of the interpolated image (interpolated frame) of the interpolated image signal inserted between frames or fields of the input image signal. Estimate the degree of. For example, when the motion vector detection accuracy is lowered, it is considered that the possibility of image corruption is high. In this case, the number of motion vector candidates increases, and it is difficult to clearly identify a motion vector with little difference in evaluation values of higher rank candidates. Therefore, when the number of motion vector candidates increases from a predetermined value, it is estimated that the interpolation frame is broken. Alternatively, when the difference between the evaluation values of the top candidates is smaller than a predetermined value, it may be estimated that the interpolation frame has failed.

  As another example of the estimation method of the interpolation frame failure, the failure of the interpolation frame may be estimated from the number of motion vector intersections. For example, in a moving image in which a human is waving, the number of motion vector intersections increases. When the number of motion vector intersections is large, it is considered that the consistency of images to be compared is not achieved. Therefore, when the number of intersections exceeds a predetermined value, it can be estimated that the interpolation frame is broken.

  Further, the estimation of the interpolation frame failure may be performed by the interpolation vector evaluation unit 11f. As described above, the interpolation vector evaluation unit 11f evaluates the motion vector detected by the motion vector detection unit 11e, and allocates an optimal interpolation vector to the interpolation block between the input frames based on the evaluation result. . At this time, a case where a plurality of interpolation vectors are assigned to one interpolation block or an interpolation block where no interpolation vector is assigned may occur. It is considered that many such cases occur when the interpolation frame is broken. Therefore, when the number of interpolation vectors assigned to one interpolation block or the number of interpolation blocks to which no interpolation vector is assigned increases beyond a predetermined value, it can be estimated that the interpolation frame has failed.

  In FIG. 3, when the motion vector detection unit 11e or the interpolation vector evaluation unit 11f is estimated that the interpolation frame fails based on the result of detecting the motion vector between consecutive frames included in the input image signal, A failure estimation signal is sent to the control unit 14. In addition, the image processing unit 13 sends a frame signal for specifying an input frame included in the input image signal to the control unit 14.

  Based on the failure estimation signal from the motion vector detection unit 11e or the interpolation vector evaluation unit 11f and the frame signal from the image processing unit 13, the control unit 14 performs interpolation frame luminance on the time base conversion unit 12d. A control signal and an input frame luminance control signal are transmitted. These luminance control signals increase the luminance level of the input frame, decrease the luminance level of the interpolation frame, and reduce the luminance of the input frame and the interpolation frame with respect to a reference luminance level preset in the liquid crystal display device. This is a control signal for controlling the average of the levels to be the reference luminance level. The reference luminance level will be described later with reference to FIG. 5, but is determined based on a gamma characteristic set in advance in the liquid crystal display device, and is essential for displaying an input video signal during normal use. Brightness level.

  When the time base conversion unit 12d interpolates the interpolation frame generated by the interpolation frame generation unit 12b between the input frames, the time base conversion unit 12d converts the input frame luminance control signal and the interpolation frame luminance control signal from the control unit 14 to each other. Based on this, the electrode driver 15 is instructed to display the luminance level of the input frame higher than the reference luminance level and display the luminance level of the interpolation frame lower than the reference luminance level. Note that the average of the luminance levels of the input frame and the interpolated frame is the reference luminance level.

  In the above example, the degree of image failure is estimated by using a predetermined value as to whether or not the image is broken (that is, whether or not the image is broken). The degree may be estimated in a plurality of stages such as large, medium, and small. In this case, the motion vector detection unit 11e or the interpolation vector evaluation unit 11f, which is an image failure estimation means, determines, for example, whether the index (the number of motion vector candidates) indicating the degree of image failure of the interpolation frame is large, medium, or small. It is determined whether or not there is, and the degree of image failure (large, medium, and small) is estimated based on the determination result. The control unit 14 sends a luminance control signal for changing the luminance level of the input frame and the interpolation frame to the time base conversion unit 12d in accordance with the degree of image failure. The time base conversion unit 12d changes the luminance levels of the input frame and the interpolation frame in accordance with the luminance control signal from the control unit 14.

  As described above, as an index for estimating the degree of image failure, as described above, the number of motion vector candidates, the difference between evaluation values of higher rank candidates, the number of motion vector intersections, and the interpolation vector assigned to one interpolation block The number, the number of interpolation blocks to which no interpolation vector can be assigned, etc. are conceivable. For example, table data that associates these index levels (large, medium, small, etc.) with the amount of change in the luminance level of the input frame and the interpolation frame may be stored in a memory (not shown). Illustrating the number of motion vector candidates, the number of candidates is divided into stages such as less than 5 (small degree), 5 or more and less than 10 (degree is medium), 10 or more (degree is large), etc. Since the degree of failure is estimated to be small, the amount of change in the luminance level of the interpolation frame is relatively small. On the other hand, if it is 10 or more, the degree of image failure is estimated to be large. If a setting is made such that the amount of change in luminance level is relatively large, image quality deterioration can be effectively reduced according to the degree of image corruption.

  As described above, in the motion compensation type FRC processing, when a failure of the interpolation frame is estimated, the luminance level of the interpolation frame is lowered and darkened while the FRC is turned on, thereby causing the failure of the interpolation frame. It is possible to make the deterioration of image quality due to the inconspicuous. In addition, since the decrease in the maximum luminance due to the decrease in the luminance level of the interpolation frame is compensated by increasing the luminance level of the input frame, the original luminance level is maintained for the viewer's eyes. felt.

  Here, the lower the luminance level of the interpolated frame (closer to black), the larger the luminance difference between the interpolated frame and the input frame, and the flicker tends to stand out. Therefore, the luminance level of the interpolated frame is the reference luminance level. It is desirable not to greatly change The luminance level for the input frame and the interpolated frame may be set by the calculation by the control unit 14 each time, or a lookup table for setting the luminance level is provided and performed based on this table. May be.

  FIG. 4 is a diagram for explaining an example of the FRC process at the time of image failure by the liquid crystal display device of the present invention. In the figure, f1 to f3 denote input frames included in the input image signal, and i1 and i2 denote interpolation frames to be interpolated between the input frames. As described above, when receiving the failure estimation signal from the motion vector detection unit 11e or the interpolation vector evaluation unit 11f, the control unit 14 causes the FRC unit 10 to set the luminance levels of the input frames f1 to f3 based on the reference luminance level. The brightness control signal is sent to set the brightness level of the interpolation frames i1 and i2 to be lower than the reference brightness level. The FRC unit 10 sets the luminance levels of the input frames f1 to f3 and the interpolation frames i1 and i2 according to the luminance control signal from the control unit 14.

  FIG. 5 is a diagram illustrating an example of gamma characteristics applied to the FRC process illustrated in FIG. In the figure, the vertical axis represents display luminance and the horizontal axis represents gradation. 5A shows a gamma characteristic (reference luminance level) during normal use of the liquid crystal display device, and FIG. 5B shows a gamma characteristic applied to the input frames f1 to f3 at the time of image failure, and FIG. Indicates a gamma characteristic applied to the interpolation frames i1 and i2 at the time of image failure. Thus, the input frames f1 to f3 have a gamma characteristic that increases the luminance level of the intermediate gradation, and the interpolation frames i1 and i2 have a gamma characteristic that decreases the luminance level of the intermediate gradation. Note that the average of the luminance level of the input frame and the luminance level of the interpolated frame is the reference luminance level shown in FIG.

As described above, according to the present invention, in the motion compensation type FRC processing, the luminance of the interpolated image is reduced and darkened at the time of image failure, thereby improving the dynamic reaction speed and reducing the image quality deterioration due to the image failure. Can be reduced.
In addition, when the luminance of the interpolated image is lowered without turning off the FRC processing at the time of the image failure, since the luminance of the original image is increased to compensate, the effect of FRC by motion compensation is maintained, A decrease in the maximum luminance can be suppressed.

It is a block diagram which shows the structural example of the motion compensation type frame rate conversion part with which the image display apparatus of this invention is provided. It is a figure for demonstrating an example of the interpolation frame production | generation process by a frame production | generation part. It is a block diagram which shows the principal part structural example of the liquid crystal display device which concerns on one Embodiment of this invention. It is a figure for demonstrating an example of the FRC process at the time of the image failure by the liquid crystal display device of this invention. It is a figure which shows an example of the gamma characteristic applied to the FRC process shown in FIG. It is a block diagram which shows schematic structure of the FRC drive display circuit in the conventional liquid crystal display device. It is a figure for demonstrating the frame rate conversion process by the conventional FRC drive display circuit shown in FIG. It is a figure for demonstrating the interpolation frame production | generation process by a motion vector detection part and an interpolation frame production | generation part. It is a figure for demonstrating the method to insert the same image as an original image darkly (it reduces brightness) between frames.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,100 ... Frame rate conversion (FRC) part, 11 ... Vector detection part, 11a ... Luminance signal extraction part, 11b ... Pre-processing filter, 11c ... Frame memory for motion detection, 11d ... Initial vector memory, 11e, 101 ... Motion Vector detection unit, 11f ... interpolation vector evaluation unit, 12 ... frame generation unit, 12a ... frame memory for interpolation, 12b, 102 ... frame generation unit for interpolation, 12c ... frame memory for time base conversion, 12d ... time base conversion 13, image processing unit, 14, control unit, 15, 103, electrode driving unit, 16, 104, liquid crystal display panel.

Claims (7)

Rate conversion means for converting the number of frames or the number of fields of the input image signal and outputting it to the display panel by interpolating the image signal subjected to motion compensation between frames or fields of the input image signal An image display device,
Image failure estimation means for estimating the degree of image failure of an interpolated image signal interpolated between frames or fields of the input image signal,
The rate conversion means makes the luminance level of the interpolated image signal lower than the luminance level of the input image signal when the image corruption estimating means estimates that the interpolated image of the interpolated image signal is corrupted. An image display device characterized by the above.   The image display device according to claim 1, wherein the rate conversion unit changes a luminance level of the input image signal and the interpolated image signal according to a degree of failure of the interpolated image. Image display device.   3. The image display device according to claim 1, wherein when the interpolated image is estimated to fail, a luminance level of the input image signal is set to a reference luminance level preset in the image display device. An image display device, wherein the luminance level of the interpolated image signal is increased, the luminance level of the interpolated image signal is decreased, and an average of luminance levels of the input image signal and the interpolated image signal is controlled to be the reference luminance level.   4. The image display device according to claim 1, wherein the image failure estimation unit determines the degree of image failure of the interpolated image signal based on the number of motion vector candidates in the rate conversion unit. 5. An image display device characterized by estimating.   4. The image display apparatus according to claim 1, wherein the image corruption estimation unit is configured to perform image corruption of the interpolated image signal based on a vector allocation state to the interpolated image in the rate conversion unit. 5. An image display device characterized by estimating the degree of.   4. The image display device according to claim 1, wherein the image failure estimation unit determines a degree of image failure of the interpolated image signal based on a number of motion vector intersections in the rate conversion unit. 5. An image display device characterized by estimating.   7. The image display device according to claim 1, wherein the rate conversion unit includes a motion vector detection unit that detects motion vector information between consecutive frames or fields included in the input image signal. An interpolation vector allocating unit that allocates an interpolation vector between the frames or between the fields based on the detected motion vector information, and an interpolation image generating unit that generates an interpolation image signal from the allocated interpolation vector And an image interpolating unit for interpolating the generated interpolated image signal between the frames or the fields.

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