JP2002215111A - Video display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a moving picture from blurring in a video display device using a hold type display device. SOLUTION: A frame memory part 1 stores a frame of input video signals. A frame rate conversion signal generator 2 generates a clock signal, a horizontal synchronous signal, and a vertical synchronous signal converted from a clock signal, a horizontal synchronous signal, a vertical synchronous signal synchronized with the input video signal at a three times or more transformation magnification. A video signal switching part 3 switches between an output signal of the frame memory part 1 and a black level fixed video signal based on a switching signal outputted from a switching signal generator 4 and outputs either of them. Then, a display period of one frame video is arbitrarily shorten.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display apparatus using a hold type display device represented by a liquid crystal panel.

[0002]

2. Description of the Related Art FIG. 5 shows a configuration of a conventional video display device using a liquid crystal panel module 5. When an input video signal a is given, the hold type display device holds each pixel value at a frame cycle and displays a video. As a typical device of the hold type display device, there is a liquid crystal panel module. In the hold-type display device, when an image is displayed, the display luminance of each pixel becomes a substantially constant value during one frame period of the image, that is, the screen is in a so-called "lit state" during one frame.

On the other hand, in a CRT which has been used for displaying an image, a phosphor irradiated with an electron beam at the time of scanning emits light instantaneously, but its luminance subsequently decreases due to the afterglow characteristic. The afterglow characteristic at this time is sufficiently short with respect to one frame time of an image. That is, the CRT shows an impulse response, and the time during which light is emitted within one frame can be said to be sufficiently shorter than that of the hold type.

[0004]

According to the display characteristics of such a hold-type device, when displaying a moving image, image quality degradation due to moving image blur is inevitable. For details of this, see "Image quality of moving image display on hold-type display" Yashiro Kurita, IEICE Technical Report 1999-0
6, pp. 55-60 etc. In short, the motion of the image displayed on the hold-type device is followed by the viewer's eyeball, so that the moving image can be blurred. Even if the response speed of the display device is improved, its effect is limited. However, conventionally, efforts have been made to increase the response speed of the display device itself, and no effective improvement has been made by circuits.

The present invention has been made in view of such a conventional problem, and an object of the present invention is to improve image quality deterioration due to moving image blur in a video display device using a hold type display device.

[0006]

According to a first aspect of the present invention, there is provided a frame memory unit for storing an input video signal in frame units, a clock signal synchronized with the input video signal,
A frame rate conversion signal generator for generating a clock signal, a horizontal synchronization signal, and a vertical synchronization signal, each of which is obtained by converting a frame rate of a video signal from a horizontal synchronization signal and a vertical synchronization signal at a conversion magnification of 3 times or more; A video signal switching unit that switches and outputs an output signal of the unit and a black level fixed video signal based on a switching signal, and a video switching signal that is turned on and off in units of a conversion frame rate by the frame rate conversion signal generation unit, A switching signal generation unit that is generated based on a vertical synchronization signal output from a frame rate conversion signal generation unit and a vertical synchronization signal synchronized with the input video signal, and is provided to the video signal switching unit. It is assumed that.

According to a second aspect of the present invention, in the video display device according to the first aspect, the switching signal generator controls on / off control of an externally input ON / OFF state in a frame unit of the video switching signal. It is characterized in that a function of variably controlling with a signal has been added.

According to a third aspect of the present invention, in the video display device according to the first or second aspect, the video signal switching unit replaces the video signal with a fixed black level with the output video of the frame memory unit. An output signal of a gain control unit for controlling the amplitude of the signal is input.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a video display device according to an embodiment of the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 1 is a configuration diagram of a video display apparatus according to Embodiment 1 of the present invention. The frame memory unit 1 in FIG. 1 is a frame memory that stores a video signal a input from the outside in frame units, for example, for one frame. The frame rate conversion signal generator 2 converts the frame rate based on the clock WCK synchronized with the video signal a, the horizontal synchronization signal WHD, and the vertical synchronization signal WVD. As a result, the converted clock RCK and the horizontal synchronization signal RH are converted.
D and a circuit for generating the vertical synchronization signal RVD. The video signal switching unit 3 is a circuit that switches and outputs the output video signal b from the frame memory unit 1 and the black level video signal i based on the switching signal g. Switching signal generator 4
Is a circuit that receives the horizontal synchronizing signal WHD and the vertical synchronizing signal RVD and generates a switching signal g for the video signal switching unit 3.

The operation of the video display device having such a configuration will be described. The video signal a supplied from the outside is written into the frame memory unit 1 for one frame by using the clock WCK, the horizontal synchronizing signal WHD, and the vertical synchronizing signal WVD in the frame memory unit 1 as a clock on the writing side. In the frame rate conversion signal generator 2, the clock WCK, the horizontal synchronization signal WHD, the vertical synchronization signal WVD
Based on the conversion rate m (m
Is a natural number of 3 or more, preferably an odd number), and generates a clock RCK, a horizontal synchronizing signal RHD, and a vertical synchronizing signal WVD matched with the frame rate, and uses these clocks and signals to generate a Read video signals with different frame rates. Assuming that the frame period of the input video signal a is T and the frame period of the output video signal is t, t = T / m.

FIG. 2 shows this frame rate conversion. FIG. 2A shows two consecutive frames (frame 1 and frame 2) of the video signal a. As shown in FIG. 2 (2), the output video signal b of the frame memory unit 1 is obtained by converting the frame rate of the video signal a to, for example, three times. However, the frame numbers are output shifted by one frame number.

Next, as shown in FIG. 2D, the switching signal generator 4 synchronizes the vertical synchronizing signals RVD and WVD with the frame whose frame rate has been tripled, and turns on or off in units of converted frames. A switching signal g that is turned off is generated. In the example shown in FIG. 2 (4), when the frame rate is 3
Of the three frames converted twice, the first and second frames are at H level, and the third frame is at L level.

With such a switching signal g, the video signal switching section 3 selects the output video signal b of the frame memory section 1 when the switching signal g is at the H level, and selects the black level video signal i when the switching signal g is at the L level. . As a result, as shown in FIG. 2 (3), the output signal h of the video signal switching unit 3 has the video signal a and the video signal a in the _two frames t ₁ and t ₂ among the three frames t ₁ , t ₂ and t _3. signal of the same content is sent to the liquid crystal panel module 5, a video signal of the remaining one frame t ₃ at the black level is sent. That is, in the liquid crystal panel module 5, an image is displayed for two frame periods (2t), and the image is erased for one frame period (1t) to display an all black screen.

As described above, conventionally, the moving image blur caused by the display state being continued during one frame period T of the video signal a is reduced to two thirds of one frame (2T / 3) by the above configuration. By reducing the length to, moving image blur can be improved. The frame to be displayed may be one frame period t. The frame position to be displayed may be anywhere within the _three frames t ₁ , t ₂ and t ₃ . The conversion rate m of the frame rate is set to 3 as an example.
It suffices if it is three or more. In that case, even-numbered frame rate conversion can be considered.

However, when the liquid crystal panel module 5 is used as a display device, it is necessary to drive the liquid crystal panel with an alternating current as conventionally known. This is usually
This is realized by reversing the drive polarity for each frame. Therefore, for example, when the frame rate is doubled, one of the odd-numbered and even-numbered frames is always on the erased screen side, and the other is always on the video display side, causing burn-in. To avoid this, it is necessary to change the driving method on the liquid crystal panel module 5 side, and the conventional liquid crystal panel module cannot be used, and only a special liquid crystal panel module can be used. Therefore, the conversion magnification m is preferably an odd value.

(Embodiment 2) Next, an image display apparatus according to Embodiment 2 of the present invention will be described. FIG. 3 is a configuration diagram of the video display device according to the present embodiment, and the same portions as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted. This video display device has a frame memory unit 1, a frame rate conversion signal generation unit 2,
It includes a video signal switching unit 3, a switching signal generation unit 4A, and a liquid crystal panel module 5. Switching signal generator 4A
Unlike the switching signal generator 4 shown in FIG. 1, the on / off frame position of the switching signal g can be changed by the on / off control signal j.

With respect to the operation of the video display device having such a configuration, portions different from the first embodiment will be described. In the example of FIG. 2, the on / off control signal j is set to be on or off independently for _three frames t ₁ , t ₂ , and t ₃ obtained by converting the frame rate to three times. Signal. The switching signal generator 4A receives this on / off control signal j and generates a switching signal g for setting the corresponding frame on or off. For example, it is possible to turn on the frame t ₁ and turn off the frames t ₂ and t ₃ . As a result, it is possible to control the moving image blur improvement effect in accordance with the response characteristics of the liquid crystal panel module 5.

(Embodiment 3) Next, an image display apparatus according to Embodiment 3 of the present invention will be described. FIG. 4 is a configuration diagram of a video display device according to the present embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. This video display device includes a frame memory unit 1, a frame rate conversion signal generation unit 2, a video signal switching unit 3, a switching signal generation unit 4, a gain control unit 16, and a liquid crystal panel module 5. The gain control unit 16 is a circuit that controls the amplitude of the output video signal b of the frame memory unit 1 and gives the result to the video signal switching unit 3.

With respect to the operation of the video display device having such a configuration, portions different from the first embodiment will be described. In the first embodiment, one of the two input signals to the video signal switching unit 3 is a black level video signal. In this case, in the liquid crystal panel module 5, a specific frame t
_{Although an} erasure screen is displayed by _i (i is a natural number), in the present embodiment, the amplitude of the original video signal is controlled and switched by the gain control unit 16. As a result, the erase screen is not displayed in the specific frame t _i . By performing such control, it is possible to prevent the luminance from deteriorating when the erased screen is displayed. In this case, of course, the effect of improving moving image blur is reduced, but a compromise between brightness and moving image blur can be found according to both characteristics of the liquid crystal panel module 5.

[0021]

As described above, according to the present invention, a remarkable effect can be obtained that the moving image blur caused by the hold type display device can be improved by the video signal processing without changing the display device.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a video display device according to Embodiment 1 of the present invention.

FIG. 2 is an explanatory diagram of a frame rate conversion showing an operation of each embodiment of the present invention.

FIG. 3 is a configuration diagram of a video display device according to a second embodiment of the present invention.

FIG. 4 is a configuration diagram of a video display device according to a third embodiment of the present invention.

FIG. 5 is a configuration diagram of a conventional video display device.

[Explanation of symbols]

 Reference Signs List 1 frame memory unit 2 frame rate conversion signal generation unit 3 video signal switching unit 4, 4A switching signal generation unit 5 liquid crystal panel module 16 gain control unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 5/66 102 H04N 5/66 102B F term (Reference) 2H093 NC29 ND60 5C006 AA01 AC22 AF03 AF04 AF05 AF23 AF59 BB11 BC03 BC11 BF02 FA04 FA12 FA29 5C058 AA06 BA04 BA35 BB06 BB13 BB18 5C080 AA10 BB05 DD01 DD30 EE19 FF09 GG12 JJ02 JJ04

Claims (3)

[Claims] 1. A frame memory unit for storing an input video signal in frame units, and converting a frame rate of a video signal to three times or more from a clock signal, a horizontal synchronization signal, and a vertical synchronization signal synchronized with the input video signal. A frame rate conversion signal generation unit that generates a clock signal converted by a magnification, a horizontal synchronization signal, and a vertical synchronization signal, respectively, and an output signal of the frame memory unit and a black level fixed video signal are switched based on a switching signal. A video signal switching unit to be output, and a video switching signal to be turned on / off in units of a conversion frame rate by the frame rate conversion signal generation unit, synchronized with a vertical synchronization signal output from the frame rate conversion signal generation unit and the input video signal. A switching signal generating unit that generates the video signal based on a vertical synchronization signal and provides the switching signal to the video signal switching unit. The video display device according to symptoms. 2. The switching signal generator further includes a function of variably controlling the on / off state of the video switching signal in a frame unit by an on / off control signal input from the outside. Item 2. The video display device according to Item 1. 3. The video signal switching unit inputs an output signal of a gain control unit that controls an amplitude of an output video signal of the frame memory unit, instead of the video signal having a fixed black level. The image display device according to claim 1.