KR100825355B1 - Image display apparatus and method for driving the same - Google Patents

Abstract

The image display device divides one field into a plurality of weighted subfields, and combines the plurality of subfields to perform multi-gradation display on the display panel. The motion detection circuit 50 and the diffusion calculation circuit 52 ) And a diffusion circuit 53. The motion amount detection circuit 50 detects the motion amount from the current field and the field before the current field from the input image signal. Further, the diffusion amount calculating circuit 52 calculates a diffusion amount for spreading the pseudo contour noise around based on the gray level of the input image signal and the detected motion amount. The diffusion circuit 53 then performs diffusion processing based on the calculated diffusion amount. As a result, the pseudo contour can be reduced and the image quality of the moving picture display can be improved without the occurrence of new noise or the increase of the circuit scale.

Multi-tone signal processing circuit, path, display panel, motion detection circuit, dither circuit

Description

IMAGE DISPLAY APPARATUS AND METHOD FOR DRIVING THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device and a driving method thereof. In particular, one field such as a plasma display panel (PDP) is divided into a plurality of weighted subfields, and the plurality of subfields are divided. The present invention relates to an image display device which performs multi-gradation display on a display panel in combination, and a driving method thereof.

In recent years, with the increase in the size of the display device, a thin display device is required, and various thin display devices are provided. For example, a matrix panel that displays a digital signal as it is, that is, a gas discharge panel such as a PDP, a matrix panel such as a DMD (Digital Micromirror Device), an EL (Electro-Luminescence) display element, a fluorescent display tube, a liquid crystal display element, or the like is provided. It is. Among such thin display devices, the gas discharge panel is easy to display on a large screen because of a simple process, a good display quality with a self-luminous type, and a fast response speed. It has been put to practical use as a display device for use.

For example, a plasma display device installs a plurality of weighted subfields (SF: light emitting blocks) constituted by a plurality of sustain discharge pulses (sustain pulses) in each field (frame), and turns each subfield on or off. By turning it on (non-lighting), image display is performed by multi-gradation control. In an image display device which controls the lighting / non-lighting of a plurality of subfields and performs multi-gradation display, false contour (pseudo contour) noise is generated in the contour portion of a moving image, and therefore, pseudo-configuration is simple. It is desired to provide an image display device and a driving method thereof capable of reducing the outline.

In a conventional plasma display device, a liquid crystal display device, an EL display device, and the like, one field is divided into a plurality of subfields having a predetermined luminance ratio (weighting), and a lighted state or a non-lighted state for each image display cell in units of a predetermined weighted subfield. There is provided an image display device (multi-gradation image display device) for performing encoding by multi-gradation control and performing image display. In an image display device in which such one field is divided into a plurality of weighted subfields, and the plurality of subfields are combined to perform multi-gradation display on the display panel, the screen size of the display panel, the number of pixels, or the image actually displayed ( Image), the person (viewer) who sees the image display device recognizes the pseudo contour when the user moves the target object moving over an arbitrary speed in the display panel.

As a technique for reducing the pseudo contour, a dither method, a superposition method, or a path switching method has been proposed, but it cannot be satisfactorily satisfied. On the contrary, the dither method or the superposition method has a hatch shape. In some cases, the side effects of noise appearing and granular noise due to the error diffusion of the sub-paths have occurred.

A conventional image display device which divides one field into a plurality of weighted subfields and combines the plurality of subfields to perform multi-gradation display on a display panel, wherein pseudo contour noise is generated without generation of flicker. To prevent the problem, the sustain period of each subfield period is set to approximately the same length within one field period, and on the display panel, an image in which the image data is expressed with N + 1 gradations at luminance levels of 0 to N. A display apparatus is proposed (for example, refer patent document 1).

Further, an image display apparatus which divides one conventional field into a plurality of weighted subfields and combines the plurality of subfields to perform multi-gradation display on a display panel, wherein the possibility of generating pseudo contour noise is obtained as the amount of noise, and There has also been proposed an image display device in which a diffusion process for reducing pseudo contour noise is performed on a region where occurrence of pseudo contours is predicted in an image based on the value of the noise amount (see, for example, Patent Document 2).

Further, an image display apparatus which divides one conventional field into a plurality of weighted subfields and combines the plurality of subfields to perform multi-gradation display on a display panel, which reduces pseudo contours and suppresses occurrence of pattern noise. In order to improve the image quality of the moving picture display, an area of gray level in which only one of a plurality of subframes having the same luminance weighting according to the superimposition method is lit, and an area in which the luminance gradient between adjacent pixels is a value within a setting range. An image display device in which the superimposition method is applied to the present invention is also proposed (see Patent Document 3, for example).

[Patent Document 1] Japanese Unexamined Patent Publication No. 10-031455

[Patent Document 2] Japanese Unexamined Patent Publication No. 11-231827

[Patent Document 3] Japanese Unexamined Patent Publication No. 2002-372948

As described above, there is a problem of pseudo contour in the conventional image display apparatus in which one field is divided into a plurality of weighted subfields, and the plurality of subfields are combined to perform multi-gradation display on the display panel. As a technique for reducing the pseudo contour, a dither method, a superposition method, or a path switching method is known. For example, in the superposition method, a hatch-shaped noise is recognized in a moving image as a side effect of the superposition. This hatch-shaped noise is recognized when the video is moving slowly, but it is difficult to recognize when the video is moving relatively fast. This is considered to be because the line of sight moves across a plurality of pixels when the video is moving fast, so that hatch-shaped noise is removed.

In the above-described Patent Document 1, the pseudo contour can be prevented by switching the main path and the sub path, but the noise due to the error diffusion of the sub path is prominent regardless of the speed of motion of the moving image area in the moving image, and the sub path Since the switching shock between the main path and the main path (the granular noise of the error diffusion of the sub-path with respect to the smooth gradation representation of the main path) was large, the viewers were also uncomfortable as an image.

Moreover, although patent document 2 reduces pseudo contour noise in the area | region where pseudo contour noise may generate | occur | produce based on the prediction result by a pseudo contour noise detection apparatus, determination of the pseudo contour based on the output of a motion detector The logical operation of pixel values with respect to the surrounding pixels of each pixel of the input image divided into a plurality of subfields is performed for each subfield, and the spatial pseudo-occurrence occurrence location is detected to perform pseudo contour reduction modulation. To do. However, since it is known that the pseudo contour is generated in the moving picture and when the predetermined gray scale is driven for display, the pseudo contour noise detection device is not necessary, and it is only necessary to be able to detect the motion amount, and the configuration is redundant.

Moreover, in patent document 3, although the hatch-shaped noise by the moving part specific gradation superimposition method can be reduced, even if it is an image moving at the same speed, a pseudo outline is easy to stand out. If the determination threshold value to be superimposed is not exceeded, superimposition is not performed and the pseudo outline is recognized. In addition, even if the pseudo contour is difficult to stand out, when the determination threshold value to be superimposed is exceeded, superimposition may be performed and a hatch-shaped noise may be recognized. The intensity of this hatch-shaped noise cannot be controlled and is determined depending on the lighting pattern.

As described above, all of the conventional methods for reducing pseudo contours detect a place where pseudo contours are generated and add modulation thereto. Therefore, the circuit size is increased and costs are increased. In addition, the conventional technique has a problem that new noise is generated as a side effect of reducing the pseudo contour.

SUMMARY OF THE INVENTION In view of the problems of the prior art for reducing the pseudo contour described above, the present invention provides an image display apparatus capable of reducing image quality and improving image quality of a moving image display without involving new noise generation or increasing circuit scale. And the driving method thereof.

According to the first aspect of the present invention, an image display apparatus which divides one field into a plurality of weighted subfields, combines the plurality of subfields, and performs multi-gradation display on the display panel, comprising: a current field from an input image signal. And a motion amount detecting circuit for detecting a motion amount from a field before the current field, and a diffusion amount for spreading pseudo contour noise to the surroundings based on the gray level of the input image signal and the detected motion amount. There is provided an image display device comprising a diffusion amount calculation circuit for calculating a and a diffusion circuit for performing a diffusion process with the diffusion amount calculated by the diffusion amount calculation circuit.

According to the second aspect of the present invention, an image display apparatus which divides one field into a plurality of weighted subfields and combines the plurality of subfields to perform multi-gradation display on the display panel, wherein the predetermined gray level is obtained from an input image signal. A path switch circuit which switches and outputs one of a main path for generating a number of signals, a sub path for generating a signal having a lower gradation number than the main path, and one of a signal for generating the main path and a signal for generating the sub path; And a motion amount detection circuit for detecting an area moving between the current field and the field before the current field from the input image signal, and outputting a motion amount which is a moving amount, and a video pseudo contour is generated by the main path. A level detecting circuit for detecting the level amount of the intensity of the pseudo contour in the case of being made; and the detected motion amount and the The pass switch circuit is compared with a predetermined set value based on the level level, and the sub-pass determination circuit determines a gray scale having a strong pseudo contour generating intensity in the moving picture area, and the pass switch circuit according to the determination result of the sub-pass determination circuit. A sub-pass switch for switching the output from the output of the main path to the output of the sub-path, and a diffusion coefficient for generating a diffusion coefficient depending on the gradation of the input image signal for calculating the amount of diffusion for spreading pseudo contour noise around A generation circuit, a diffusion amount calculating circuit that calculates a diffusion amount based on the movement amount and the diffusion coefficient, and a diffusion circuit which performs a diffusion process with the diffusion amount calculated by the diffusion amount calculating circuit, An image display apparatus is characterized by reducing a pseudo contour by controlling a switch and the diffusion amount. Ball.

According to the third aspect of the present invention, an image display apparatus which divides one field into a plurality of weighted subfields, combines the plurality of subfields, and performs multi-gradation display on the display panel, wherein the predetermined gray level is obtained from an input image signal. A main path for generating a number of signals, a sub path for generating a signal having a lower gradation number than the main path, a diffusion processing path for generating a signal subjected to diffusion processing on the input image signal, and generation of the main path A path switch circuit for switching and outputting any one of a signal, a generation signal of the subpath, and a generation signal of the diffusion process path, and an area moving between a current field and a field before the current field from the input image signal. A motion detection circuit which detects and outputs a motion amount which is a moving amount and the main path A level detecting circuit for detecting the level amount of the intensity of the pseudo contour when an image pseudo contour is generated, and comparing the detected motion amount and the detected level amount with predetermined set values, and generating a pseudo contour in the video region. A path switching determination circuit for determining a strong gradation and a result of the path switching determination circuit determine the path switch circuit as one of the output of the main path, the output of the sub path, or the output of the diffusion process path. A path switching circuit for switching, a diffusion coefficient generating circuit for generating a diffusion coefficient depending on the gradation of the input image signal for calculating a diffusion amount for spreading pseudo contour noise to the surroundings, and based on the motion amount and the diffusion coefficient The diffusion amount calculation circuit for calculating the diffusion amount and the diffusion amount calculated by the diffusion amount calculation circuit. Comprising a spreading circuit for, and the image display device, comprising a step of controlling the switching circuit and the path of the diffusion amount of reducing false contour is provided.

According to the fourth aspect of the present invention, an input image signal is a driving method of an image display device in which one field is divided into a plurality of weighted subfields, and the plurality of subfields are combined to perform multi-gradation display on the display panel. A motion amount detecting step of detecting a motion amount from the current field and a field previous to the current field, and a diffusion amount for spreading pseudo contour noise to the periphery based on the gray level of the input image signal and the detected motion amount. A diffusion method calculating step and a diffusion step of performing a diffusion process by the calculated diffusion amount are provided.

According to the fifth aspect of the present invention, one field is divided into a plurality of weighted subfields, the plurality of subfields are combined to perform multi-gradation display on the display panel, and a signal having a predetermined number of tones is input from the input image signal. An image having a main path to be generated, a sub path for generating a signal having a lower gradation number than the main path, and a path switching step of switching and outputting any one of the main signal and the sub-signal generated signal; A driving method of a display device, comprising: a motion amount detecting step of detecting a region moving between a current field and a field before the current field from the input image signal, and outputting a movement amount that is a moving amount; A level detecting step of detecting the level amount of the intensity of the pseudo contour when a moving image pseudo contour is generated; The sub-pass determination step of comparing the output amount with the predetermined set value based on the detected motion amount and the detected level amount, and determining the gradation having a strong pseudo contour generating intensity, and the determination result of the sub-pass determination step. A sub-pass switching step of switching the path switching step from the output of the main path to the output of the sub path, and the diffusion depending on the gradation of the input image signal for calculating the amount of diffusion for spreading pseudo contour noise to the periphery. A diffusion coefficient generation step of generating a coefficient, a diffusion amount calculation step of calculating a diffusion amount based on the motion amount and the diffusion coefficient, and a diffusion step of performing a diffusion process based on the diffusion amount; And the pseudo contour is reduced by controlling the diffusion amount. The same method is provided.

According to the sixth aspect of the present invention, one field is divided into a plurality of weighted subfields, the plurality of subfields are combined to perform multi-gradation display on the display panel, and a signal having a predetermined number of gradations is input from the input image signal. A main path to be generated, a sub path for generating a signal having a lower gradation number than the main path, a diffusion processing path for generating a signal subjected to diffusion processing on the input image signal, a generated signal of the main path, and the sub A driving method of an image display device, comprising: a path switching step of switching and outputting either a path generation signal or a generation signal of the diffusion processing path, the method comprising: between a current field and a field before the current field from the input image signal; A motion detection step of detecting an area of motion in the motion path and outputting a motion amount which is a moving amount, A level detecting step of detecting the level amount of the intensity of the pseudo contour when the moving image pseudo contour is generated by the main path; and comparing the detected motion amount and the detected level amount with predetermined setting values, A path switching determination step of determining a gradation having a strong pseudo contour generating intensity in an area, and the path switching step is performed by the determination result of the path switching determination step, the output of the main path, the output of the sub path, or the diffusion processing path. A path switching step of switching to any one of the outputs, a diffusion coefficient generating step of generating a diffusion coefficient depending on the gradation of the input image signal for calculating a diffusion amount for spreading pseudo contour noise to the surroundings, the motion amount and the A diffusion amount calculating step of calculating a diffusion amount based on the diffusion coefficient and the diffusion amount calculation step Comprising a spreading step of performing a diffusion process to the acid amount, and the driving method of an image display device, comprising a step to control the amount of diffusion and the path switch step reducing the false contour is provided.

Effect of the Invention

According to the present invention, it is possible to provide an image display device and a driving method thereof capable of improving the image quality of moving image display by reducing pseudo contours without involving new noise generation or increasing circuit scale.

1 is a block diagram schematically showing an example of an image display apparatus to which the present invention is applied.

Fig. 2 is a block diagram showing an example of a multi-gradation signal processing circuit as a first embodiment of the image display device according to the present invention.

FIG. 3 is a block diagram showing an example of a path (main path) in the multi-gradation signal processing circuit shown in FIG. 2; FIG.

FIG. 4 is a block diagram showing an example of a motion amount detecting circuit in the multi-gradation signal processing circuit shown in FIG.

FIG. 5 is a diagram showing an example of SF converted data stored in an SF encoding circuit in the multi-gradation signal processing circuit shown in FIG. 2; FIG.

6 is a diagram showing an example of a drive sequence of a drive control circuit in the image display device according to the present invention;

Fig. 7 is a block diagram showing another example of a path (main path) in a multi-gradation signal processing circuit as a second embodiment of an image display device according to the present invention.

FIG. 8 is a block diagram illustrating an example of a motion adaptive dither circuit in the path of the multi-gradation signal processing circuit shown in FIG. 7. FIG.

FIG. 9A is a diagram for explaining a dither operation in one field performed by the dither amount calculating circuit in the motion adaptive dither circuit shown in FIG. 8; FIG.

FIG. 9B is a diagram for explaining a dither operation in one field performed by the dither amount calculating circuit in the motion adaptive dither circuit shown in FIG. 8; FIG.

10A is a diagram for explaining the relationship between gradation and dither coefficients in the method for driving an image display device according to the present invention;

10B is a diagram for explaining the relationship between gradation and dither coefficients in the method for driving an image display device according to the present invention;

Fig. 10C is a diagram for explaining the relationship between gradation and dither coefficients in the method for driving an image display device according to the present invention.

FIG. 11 is a block diagram showing another example of a motion adaptive dither circuit in the path of the multi-gradation signal processing circuit shown in FIG. 7; FIG.

Fig. 12A is a diagram showing the relationship between the amount of motion of the input image signal and the amount of calculation motion in the image display device according to the present invention;

Fig. 12B is a diagram showing the relationship between the amount of motion of the input image signal and the amount of calculation motion in the image display device according to the present invention.

Fig. 12C is a diagram showing the relationship between the amount of motion of the input image signal and the amount of calculation motion in the image display device according to the present invention.

Fig. 12D is a diagram showing the relationship between the amount of motion of the input image signal and the amount of calculation motion in the image display device according to the present invention.

Fig. 13 is a block diagram showing an example of a multi-gradation signal processing circuit as a third embodiment of an image display device according to the present invention.

FIG. 14 is a block diagram showing an example of subpaths in the multi-gradation signal processing circuit shown in FIG.

FIG. 15 is a block diagram showing an example of a path switch circuit in the multi-gradation signal processing circuit shown in FIG. 13; FIG.

FIG. 16 is a flowchart showing an example of a path (main path) process in the multi-gradation signal processing circuit as the first embodiment of the image display device according to the present invention shown in FIG.

FIG. 17 is a flowchart showing an example of a path (main path) process in a multi-gradation signal processing circuit as a second embodiment of the image display device according to the present invention shown in FIG.

FIG. 18 is a flowchart showing an example of processing in a multi-gradation signal processing circuit as a third embodiment of the image display device according to the present invention shown in FIG.

Fig. 19 is a block diagram showing still another example of a path (main path) in a multi-gradation signal processing circuit as a fourth embodiment of an image display device according to the present invention;

20 is a block diagram showing an example of a multi-gradation signal processing circuit as a fifth embodiment of an image display device according to the present invention;

FIG. 21 is a block diagram showing an example of a main path in the multi-gradation signal processing circuit shown in FIG. 20;

FIG. 22 is a block diagram showing an example of a path switch circuit in the multi-gradation signal processing circuit shown in FIG. 20; FIG.

FIG. 23 is a block diagram showing an example of a spreading path in the multi-gradation signal processing circuit shown in FIG. 20;

24 is a flowchart showing an example of processing in a multi-gradation signal processing circuit as a fifth embodiment of the image display device according to the present invention shown in FIG. 20;

FIG. 25 is a block diagram showing a modification of a spread path in the multi-gradation signal processing circuit shown in FIG. 20; FIG.

Explanation of the sign

1: Video signal input terminal 2: Synchronous signal input terminal

3: multi gradation signal processing circuit 4: field memory

5: drive control circuit 6: timing generation circuit

7: Display panel 10: Sub path (main path)

20, 21: Pass (main pass) 22: Diffusion pass

30, 31: pass switch circuit 40: SF coding circuit

50: motion detection circuit

51: dither coefficient generation circuit 52, 58: dither amount calculation circuit

53, 202: Dither Circuit

54-1 to 54-n: Dither gradation setting circuit

55-1 to 55-n: dither coefficient setting circuit

56-1 to 56-n: dither gradation comparison circuit 57: dither coefficient selection circuit

100: distortion correction circuit 101, 200: gain control circuit

102, 201: error diffusion circuit 103: data matching circuit

203: dither switching circuit 204: dither switching determination circuit

205 motion adaptive dither circuit 300 level detection circuit

301: sub-pass determination circuit 302: sub-pass switch

500: RGB matrix circuit 501: edge detection circuit

502: motion area detection circuit 503: motion amount determination circuit

531: dither amount addition circuit 532: dither amount subtraction circuit

533: horizontal counter 534: vertical counter

535: additive subtraction circuit

Hereinafter, each embodiment of an image display device and a driving method thereof according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram schematically showing an example of an image display apparatus to which the present invention is applied. In Fig. 1, reference numeral 1 denotes a digital video signal input terminal, 2 denotes a horizontal synchronizing signal, a vertical synchronizing signal, a synchronization signal input terminal such as a display period signal indicating a display period and a clock signal, and 3 denotes a multi-system. A harmonic signal processing circuit, 4 is a field memory, 5 is a drive control circuit, 6 is a timing generating circuit, and 7 is a display panel.

The field memory 4 can store image data for two fields, store data for one field, and then sequentially read data for each of the same subfields SF for the stored field in the next field period. It is supposed to be. The timing generating circuit 6 is a circuit for generating various timing signals such as a synchronization signal. The clock generation signal CLK, the horizontal synchronization signal Hsync, and the vertical signal are transmitted to the multi-tone signal processing circuit 3 through the terminal 6T. The synchronization signal Vsync is supplied. In addition, the display panel 7 is a display panel, such as a plasma display panel (PDP), for example, and various drivers (for example, X driver, Y driver, and address driver in a 3-electrode AC drive type PDP), etc. It includes.

<Example>

2 is a block diagram showing an example of the multi-gradation signal processing circuit 3 as the first embodiment of the image display device according to the present invention.

The multi gradation signal processing circuit 3 receives the terminal 6T from the three primary color image signals (red: Ri, green: Gi, blue: Bi) and the timing generation circuit 6 supplied from the video signal input terminal 1. Receives the clock signal CLK, the horizontal sync signal Hsync, the vertical sync signal Vsync, and the like, which are supplied through the multi-gradation process for each primary color, and is converted into data such as lighting and non-lighting of each subfield (red: Ro, green: Go, blue: Bo) are output to the field memory 4.

That is, as shown in Fig. 2, the multi-gradation signal processing circuit 3 of the first embodiment includes the path (main path) 20 and the SF encoding circuit 40, which are provided for each primary color (for example, red: R), The motion detection circuit 50 is provided. The motion detection circuit 50 receives input video signals (input image signals) (Ri, Gi, Bi) and timing signals (sync signals) (CLK, Hsync, Vsync) of three primary colors, and receives pixels from the input video signals. A motion amount MV is detected from a current field and a field before the current field in units. The path 20 receives the input video signal of the corresponding primary color (for example, Ri), the timing signal, and the motion amount MV detected by the motion amount detection circuit 50 and outputs the signal MP to the SF encoding circuit 40. . The SF encoding means 40 receives the signal MP from the path 20, and outputs the signal (for example, Ro) converted into data of lighting / non-lighting for each subfield of the corresponding primary color. These paths 20 and the SF encoding circuit 40 are provided for each primary color, respectively, and SF-coded signals Ro, Go, and Bo are obtained for each primary color.

FIG. 3 is a block diagram showing an example of a path (main path) 20 in the multi-gradation signal processing circuit shown in FIG. 2. Here, the following description will be described taking the case where the diffusion circuit is a dither as an example. In addition, the structure of the path | route 20 is the same structure regarding each signal of three primary colors, and it demonstrates mainly using red (R) as an example below.

As shown in FIG. 3, the path 20 includes a gain control circuit 200, an error diffusion circuit 201, a dither circuit 202, a dither switching circuit 203, and a dither switching determination circuit 204. . The gain control circuit 200 receives the input video signal Ri of each primary color and performs gain control, and supplies the gain-controlled video signal to the error diffusion circuit 201. The error diffusion circuit 201 performs an error diffusion process on the gain controlled video signal, and supplies the signal MPL subjected to the error diffusion process to the dither circuit 202 and the dither switching circuit 203.

The dither circuit 202 performs conventionally known dither processing. The dither circuit 202 also supplies the signal MPD subjected to the dither processing of the dither amount DL to the dither switching circuit 203. The dither switching determination circuit 204 outputs &quot; 1 &quot; when the motion amount MV is equal to or greater than the predetermined threshold value TD based on the motion amount MV detected by the motion amount detection circuit 50, and the motion amount MV is predetermined. If it is smaller than the threshold value TD, "0" is output. The dither switching circuit 203 selects the output signal MPL of the error diffusion circuit 201 when the output of the dither switching determination circuit 204 is "0" according to the output of the dither switching determination circuit 204, and When the output of the dither switching determination circuit 204 is "1", the output MPD of the dither circuit 202 is selected and supplied to the SF encoding circuit 40 as the output signal MP of the path 20.

FIG. 4 is a block diagram showing an example of the motion detection circuit 50 in the multi-gradation signal processing circuit shown in FIG.

As shown in FIG. 4, the motion amount detection circuit 50 includes an RGB matrix circuit 500, an edge detection circuit 501, a motion area detection circuit 502, and a motion amount determination circuit 503. The RGB matrix circuit 500 generates the luminance signal Y from the image signals Ri, Gi, Bi of the three primary colors supplied from the image signal input terminal 1, thereby generating the edge detection circuit 501 and the motion area detection circuit ( 502). The motion amount determination circuit 503 outputs the motion amount MV based on the output of the edge detection circuit 501 and the output of the motion area detection circuit 502.

4 shows the case where the motion amount MV is determined and output from the luminance signal Y. Although the RGB matrix circuit 500 is used, the motion amount is determined for each primary color color R, G, and B signal. It can also be configured to. In this case, the edge detection circuit 501, the movement area detection circuit 502, and the movement amount determination circuit 503 are required for each primary color signal, respectively.

FIG. 5 is a diagram showing an example of SF converted data stored in the SF encoding circuit in the multi-gradation signal processing circuit shown in FIG. 2, and contents and levels of the encoded conversion data table stored in the SF encoding circuit 40. FIG. And an example of the dither coefficient which is a diffusion coefficient. In addition, the symbol (circle) in FIG. 5 represents lighting. Specifically, in Fig. 5, for example, the gradation 17 represents the form in which the subfields SF1, SF3 and SF5 light up, and the gradation 87 represents the subfields SF1 through SF8 illuminate. 5, the level amount LV is set to 3 in gradation 17, and the dither coefficient DK is set to 2 in gradation 87, and the dither amount DL is an operation of dither coefficient DK and a predetermined value A. In FIG. Dither processing is performed by (DL = DK × A). Then, the encoded MP data table shown in FIG. 5 converts the signal MP from the path 20 to 147 gray levels.

Here, in FIG. 5, SF indicates an order of driving by the drive control circuit 5, SF1 is a first subfield driven, SF2 is a second subfield driven, and SF9 is a ninth driven subfield. Field, and SF10 is the last driven subfield. In addition, each subfield SF1 to SF10 is given a weight, and SF1: SF2: SF3: SF4: SF5: SF6: SF7: SF8: SF9: SF10 = 1: 2: 4: 8: 12: 16: 20: 24 There is a weighting factor of 28:32. The weighting of each of the subfields SF1 to SF10 corresponds to the ratio of the amount of light emission between the subfields, and for example, the gray level of the input video signal Ri supplied to the gain control circuit 200 of the path 20. When the number is 9 bits and the maximum gradation 511, the gain control is performed by the gain control circuit 200 to 147/511 times.

6 is a diagram showing an example of a drive sequence of the drive control circuit 5 in the image display device according to the present invention.

As shown in Fig. 6, in the driving sequence, for example, one field is divided into ten subfields SF1 to SF10, and display is performed by combining subfields that emit light for each display cell. Each subfield SF1 to SF10 has a reset period TS for initializing all display cells, an address period TA for setting to a state corresponding to an image displaying all display cells, and each display cell in accordance with the set state. And a sustain period (sustain discharge period) TS for emitting light. Here, the sustain period (number of sustain pulses) of each subfield SF1 to SF10 corresponds to the ratio of the amount of light emission (weighting) between the subfields. As described above, for example, SF1: SF2: SF3: SF4: SF5: SF6: SF7: SF8: SF9: SF10 = 1: 2: 4: 8: 12: 16: 20: 24: 28: 32 are determined according to the weighting ratio. In addition, the reset period TR, the address period TA, and the sustain period TS in each of the subfields SF1 to SF10 are generated by the timing generating circuit 6.

Fig. 7 is a block diagram showing another example of the path (main path) 20 in the multi-gradation signal processing circuit as the second embodiment of the image display device according to the present invention.

As can be clearly seen from the comparison of Figs. 7 and 3, the path 20 in the multi-gradation signal processing circuit 3 of the second embodiment is the dither circuit in the first embodiment described above with reference to Fig. 3. Instead of the dither switching circuit 203 and the dither switching determination circuit 204, a motion adaptive dither circuit 205 is provided. In addition, since the gain control circuit 200 and the error diffusion circuit 201 are the same as above-mentioned, the description is abbreviate | omitted.

The motion adaptive dither circuit 205 varies the dither amount according to the motion amount MV, which is the output of the motion amount detection circuit 50, and outputs the signal MP to the field memory 40.

FIG. 8 is a block diagram showing an example of the motion adaptive dither circuit 205 in the path 20 of the multi-gradation signal processing circuit shown in FIG.

As shown in FIG. 8, the motion adaptive dither circuit 205 includes a dither coefficient generating circuit 51, a dither amount calculating circuit 52, and a dither circuit 53. The dither circuit 53 is composed of a dither amount adding circuit 531, a dither amount subtracting circuit 532, a horizontal counter 533, a vertical counter 534, and an addition subtraction selecting circuit 535. The output signal (video signal) MPL of the error diffusion circuit 201 is supplied to the dither coefficient generating circuit 51, the dither amount adding circuit 531, the dither amount subtracting circuit 532, and the addition subtraction selecting circuit 535. .

The dither coefficient generating circuit 51 outputs an arbitrary dither coefficient DK to the dither amount calculating circuit 52 in a so-called modulation amount as a ratio of the intensity to which the dither to diffuse is adapted. Here, as shown in Fig. 5, the predetermined modulation amount may be output for the gray scale. The dither amount calculation circuit 52 calculates the dither amount DL, which is the diffusion amount, based on the motion amount MV and the dither coefficient DK output from the motion amount detection circuit 50, and subtracts the dither amount adding circuit 531 and the dither amount. Output to circuit 532. The dither amount DL calculation in the dither amount calculation circuit 52 is performed by DL = MV × DK, and outputs the calculated dither amount DL to the dither circuit 53.

The dither amount adding circuit 531 adds the dither amount DL calculated by the dither amount calculating circuit 52 to the signal MPL, and the dither amount subtracting circuit 532 adds the dither amount calculating circuit 52 to the signal MPL. The calculated dither amount DL is subtracted. The addition / subtraction selection circuit 535 outputs the output signal of the dither amount addition circuit 531, the output signal of the dither amount subtraction circuit, or the error diffusion circuit 201 in accordance with the outputs of the horizontal counter 533 and the vertical counter 534. Any one of the output signals MPL is selected and the signal MP is output to the SF encoding circuit 40.

9A and 9B are for explaining the dither operation in one field performed by the dither amount calculating circuit 52 in the dither circuit 202 shown in FIG. 3 or the motion adaptive dither circuit 205 shown in FIG. It is a figure and shows the result of a dither calculation. Here, Fig. 9A repeats + DL and -DL in the horizontal direction and + DL and -DL in the vertical direction. In Fig. 9B, four pixels of 2x2 are used as one block, and + DL and -DL are switched according to a predetermined rule in which one + DL and one -DL are included in one block. The size of one block is not limited to 4 pixels of 2x2, and may be larger, and the sum of + DL and -DL for adding and subtracting dither may be zero.

10A to 10C are diagrams for explaining the relationship between gradation and dither coefficients in the driving method of the image display device according to the present invention. Here, FIG. 10A shows the case where the dither coefficient DK is fixed with respect to the gray scale, FIG. 10B shows the case where the dither coefficient DK is proportional to the gray scale, and FIG. 10C shows the logarithmic dither coefficient DK with respect to the gray scale. The relationship is shown.

As shown in Fig. 10A, when the dither coefficient DK is fixed with respect to gradation, the circuit scale can be kept small.

However, since the human eye becomes more difficult to recognize the luminance difference as the luminance increases, for example, even if the luminance difference between the gray scales 3 and 14 is recognizable, the luminance difference between the gray scales 140 and the gray scale 141 cannot be recognized. As shown in Fig. 10C, the dither coefficient DK is a logarithmic relationship with respect to the gray scale, considering that the sense of the brightness of the human eye is proportional to the logarithm of the brightness from the Wafer-Fahner's law. It is most suitable for a sense. In this case, the dither coefficient attitude circuit 51 is configured by, for example, a ROM. In addition, as shown in FIG. 10B, making the dither coefficient DK proportional to the gray scale corresponds to the case in the middle of FIG. 10A and FIG. 10C described above.

FIG. 11 is a block diagram illustrating another example of the motion adaptive dither circuit 205 in the path 20 of the multi-gradation signal processing circuit 3 shown in FIG. 7. The motion adaptive dither circuit 205 shown in FIG. 11 is also a gray scale adaptive dither circuit.

As shown in Fig. 11, the motion adaptive dither circuit 205 includes a dither circuit 53, n dither gradation setting circuits 54-1 to 54-n, and n dither coefficient setting circuits 55-1 to 55-. n), n dither gradation comparison circuits 56-1 to 56-n, a dither coefficient selection circuit 57, and a dither amount calculation circuit 58 are provided. Here, the configuration of the dither circuit 53 is the same as that described with reference to Fig. 8, and the description thereof is omitted.

The dither gradation setting circuit 54-1 sets the first gradation to which dither is to be adapted, and the dither gradation setting circuit 54-2 sets the second gradation to which the dither is to be adapted, and sets the dither gradation. The circuit 54-n sets the nth gradation to which dither is to be adapted. The dither coefficient setting circuit 55-1 sets the dither coefficients in the first gradation, the dither coefficient setting circuit 55-2 sets the dither coefficients in the second gradation, and sets the dither coefficients. The circuit 54-n sets dither coefficients in the nth gradation.

Specifically, in the case of the SF conversion data shown in Fig. 5 described above, the dither gray scale setting circuit 54-1 sets gray level 3, and the dither coefficient setting circuit 55-1 sets the dither coefficient "1". The dither gradation setting circuit 54-6 sets the gradation 43, while the dither coefficient setting circuit 55-6 sets the dither coefficient "2", and the dither gradation setting circuit 54-15 sets the gradation 111. At the same time, the dither coefficient setting circuit 55-15 sets the dither coefficient "3". In the case of the SF converted data shown in Fig. 5, since the number of gray scales (the gray scales in which "1", "2" or "3" is written) as the dither coefficient is 19 pieces (n is 19), Nineteen dither gradation setting circuits 54-1 to 54-19, dither coefficient setting circuits 55-15 to 55-19, and dither gradation comparison circuits 56-1 to 56-19 are required.

Here, the gray scale for adapting dither is a gray scale in which pseudo contours are easily recognized. In addition, the dither coefficient represents the ratio of the intensity of adapting the dither to the gray scale to which the dither is to be adapted, and the dither coefficient is not limited to "1", "2" or "3". In addition, the gradation to adapt the dither can be variously changed by the SF conversion data (driving sequence) to be applied.

The dither gradation comparison circuits 56-1 to 56-n are output signals of the corresponding dither gradation setting circuits 54-1 to 54-n and the error diffusion circuit 201 (input signals of the motion adaptive dither circuit 205). ) The MPLs are compared, and if "1" is matched, "1" is outputted, and if not, "O" is outputted. The dither coefficient selecting circuit 57 outputs a signal corresponding to the dither gray scale comparison circuits 56-1 to 56-n outputting "1" to the dither amount calculating circuit 58, and dither amount calculating circuit 58 Performs the dither amount DL operation using the dither coefficients set in the dither coefficient setting circuits 55-1 to 55-n corresponding to the dither gray scale comparison circuits 56-1 to 56-n that output the "1". . Here, the dither amount DL calculation in the dither amount calculation circuit 58 can be performed by applying any of the methods shown in Figs. 12A to 12D, for example. The dither amount DL calculation in the dither amount calculation circuit 58 is performed by DL = MVC x DK, and the calculated dither amount DL is output to the dither circuit 53. In other words, when the dither amount DL is calculated, the motion amount MV is first converted into a practical motion amount MVC based on practical use, and the dither amount DL is obtained using the calculated amount of motion MVC.

12A to 12D are diagrams showing the relationship between the motion amount MV and the calculation motion amount MVC of the input image signal in the image display device according to the present invention.

12A is a diagram showing a first calculation method of the calculated motion amount MVC with respect to the motion amount MV. When the motion amount MV is smaller than the predetermined threshold value TD, the calculated motion amount MVC is set to 0, and the motion amount MV is the predetermined threshold value. In the case of TD or more, the arithmetic motion MVC is fixed to a predetermined value DFL. Fig. 12B is a diagram showing a second calculation method of the calculation motion amount MVC with respect to the motion amount MV, and the motion amount MV and the calculation motion amount MVC are in proportional relationship.

12C is a diagram showing a third calculation method of the calculated motion amount MVC with respect to the motion amount MV. When the motion amount MV is smaller than the predetermined threshold value TD, the calculated motion amount MVC is set to 0 and the motion amount MV is the predetermined threshold value. In the case of TD or more, the motion amount MV and the calculation motion amount MVC are proportional to each other. 12D is a diagram showing a fourth calculation method of the calculated motion amount MVC with respect to the motion amount MV. When the motion amount MV is smaller than the predetermined threshold value TD, the calculated motion amount MVC is set to 0, and the motion amount MV is the predetermined threshold value. In the case of TD or more, the calculation motion amount MVC is made to be proportional to the MV-TD.

Fig. 13 is a block diagram showing an example of the multi-gradation signal processing circuit 3 as the third embodiment of the image display device according to the invention. In Fig. 13, reference numeral 10 denotes a sub path, 20 a main path, 30 a path switch circuit, 40 an SF coding circuit, and 50 a motion detection circuit. That is, the third embodiment shown in FIG. 13 shows a case where the present invention is applied to an image display device of the path switching method.

As can be clearly seen from the comparison between FIG. 13 and FIG. 2 described above, the multi-gradation signal processing circuit 3 of the third embodiment has a subpath 10 and a main path 20 for each primary color, and the subpath 10 And the output of either the main path 20 or the main path 20 are selected by the path switch circuit 30 and supplied to the SF encoding circuit 40. Here, the sub path 10 is for displaying the input image signal at a predetermined gradation level (for example, a gradation level less than the gradation level of the input image signal), and the main path 20 actually displays the input image signal. Can be displayed in gradation level. The path switch circuit 30 selects an output signal of either the sub path 10 or the main path 20 in accordance with the motion amount MV detected by the motion amount detection circuit 50, and the SF encoding circuit 40. Will output

FIG. 14 is a block diagram showing an example of a sub path 10 in the multi-gradation signal processing circuit shown in FIG. Here, the sub-pass circuit 10 is configured to express the image using a lighting pattern in which pseudo contours are not generated. For example, in the case of the SF conversion data of FIG. 5 described above, gray scales 0, 1, 3, 7, 11 gray scales of 15, 27, 43, 63, 87, 111, and 147 are used, and an error spread between these gray scales is expressed.

As shown in FIG. 14, the subpath 10 includes a distortion correction circuit 100, a gain control circuit 101, an error diffusion circuit 102, and a data matching circuit 103. The distortion correction circuit 100 does not increase the number of gradations that can be expressed in the subpath 10 evenly with the amount of luminance, so that the display characteristics after error diffusion and the inverse function are corrected so that the linear display characteristics as a whole are corrected. It is a circuit which corrects in order to obtain. The gain control circuit 101 multiplies a predetermined gain coefficient with respect to the input image signal so that the error diffusion circuit 102 at the rear stage can perform error diffusion processing over the entire area of the input image signal. . In addition, the gain control circuit 101 can be comprised with a general multiplier, ROM, or RAM.

The error diffusion circuit 102 performs an error diffusion with respect to the image signal obtained through the gain control circuit 101, thereby artificially generating halftones to increase the number of grayscales. The data matching circuit 103 is provided for matching the brightness level in the sub path 10 to the brightness level in the main path 20.

FIG. 15 is a block diagram showing an example of a path switch circuit 30 in the multi-gradation signal processing circuit shown in FIG.

As shown in FIG. 15, the pass switch circuit 30 includes a level detection circuit 300, a sub path determination circuit 301, and a sub path switch 302. The level detection circuit 300 detects a gray level in which pseudo contours tend to come out for each pixel, and outputs the generated intensity (level amount) LV when a pseudo contour is generated. The sub path determination circuit 301 outputs the path determination signal PSW based on the output LV of the level detection circuit 300 and the output (movement amount) MV of the movement amount detection circuit 50. The subpath switch 302 selects the output SP of the subpath 10 according to the subpath determination signal PSW input from the subpath determination circuit 301, for example, when the subpath determination signal PSW is "1". When the sub path determination signal PSW is &quot; 0 &quot;, the output MP of the main path 20 is selected and output to the SF encoding circuit 40.

Here, the path determination signal PSW outputs &quot; 1 &quot; when the motion amount MV is equal to or greater than the predetermined value TMP and the level amount LV is equal to or greater than the predetermined value TLP, and the motion amount MV is smaller than the value TMP or level. When the amount LV is smaller than the value TLP, "0" is output. The value TMP and the value TLP differ depending on the screen size, the number of pixels, and the like of the display panel 7, and use a value determined by the rule of thumb. More specifically, for example, in the above-described SF conversion data of FIG. 5, the value of "0" to "5" is determined for each gray level. The values of "0" to "5" of the level amount LV are numerical values representing the intensity when the pseudo contour is recognized, and "5" is set to the gray level when the pseudo contour recognized is the strongest.

Next, the generation intensity of the pseudo outline will be described. In a moving image, when a predetermined gradation is applied between adjacent pixels of the video signal, a person (a person who is looking at an image display device) recognizes a pseudo outline. Here, the predetermined gradation means that there are digits between the upper and lower gradations, and for example, the gradations 4, 8, 16, 28, 44, 64, 88, and 112 in the SF conversion data of FIG. These gradations are first-order rounded gradations, and pseudo contours are easily recognized. Incidentally, the gradations 32, 48, 68, 92 and 120 are the second digit raising gradations, and the pseudo outline is easy to be recognized, but the pseudo outline is not as strong as the first gradation.

As described above, in Fig. 5, the level amount LV is represented in five levels as the intensity when a pseudo contour is generated, and the level amounts LV of gradation 44, 64, 88 and 112 are &quot; 5 &quot; The level LVs of the above gray scales 45, 65, 89, and 113 are also "5". This is because when the number of digits is increased between adjacent pixels in the actual video signal, the gradation in which the digits are raised is not limited to the gradation 44, 64, 88, or 112, so that the level amount LV of one gradation is also &quot; 5 &quot;. It is set to.

Levels LV above and above "1" are gradations with the number of digits in the subfield increasing in the lighting pattern, and `` 4 '', `` 3 '', `` 2 '', and `` 1 '' of the level amounts LV are the same as the continuous gradations. It is a level amount. Instead of detecting the level amount LV, it is possible to detect the place where the number of digits is raised between adjacent pixels.

FIG. 16 is a flowchart showing an example of the processing of the path (main path) 20 in the multi-gradation signal processing circuit as the first embodiment of the image display device according to the present invention shown in FIG. 3, and includes a dither switching circuit 203 and a dither. This is for explaining the processing of the switching determination circuit 204.

First, when the processing is started in step 110, the process proceeds to step 111 to perform initialization, and the dither switching determination circuit 204 outputs "0". The dither switching circuit 203 also selects the output signal MPL of the error diffusion circuit 201. Subsequently, the procedure proceeds to step 113, where the motion amount MV is detected, and in step 114, the dither amount DL is added and subtracted. As the dither coefficient DK, any of the above-described Figs. 10A to 10C may be applied, or the dither coefficient of Fig. 5 may be used.

In addition, the flow proceeds to step 115, where the motion amount MV is compared with a predetermined threshold (decision threshold) TD. If it is determined in step 115 that the motion amount MV is smaller than the determination threshold value TD, the flow proceeds to step 116, the dither switching determination circuit 203 outputs "0", and proceeds to step 117 further, and the dither switching circuit 203 ) Selects the output signal MPL of the error diffusion circuit 201 and returns to step 113. On the other hand, if it is determined in step 115 that the movement amount MV is equal to or larger than the determination threshold value TD, the flow proceeds to step 118, and the dither switching determination circuit 203 outputs "1" and proceeds to step 119, and the dither switching circuit 203 selects the output signal MPD of the dither circuit 202 and returns to step 113. Here, the above processing is performed every pixel, every predetermined area, or every primary color signal. In addition, the output signal MPL of the error diffusion circuit 201 selected by the dither switching circuit 203 or the output signal MPD of the dither circuit 202 is the output signal MP of the pass (main path) 20 as the SF encoding circuit 40. Is supplied.

FIG. 17 is a flowchart showing an example of the path (main path) processing in the multi-gradation signal processing circuit as the second embodiment of the image display device according to the present invention shown in FIG. 7, and describes the processing of the motion adaptive dither circuit 205. It is to. Here, FIG. 12C applies to the relationship between the motion amount MV and the calculation motion amount MVC. As the dither coefficient DK, any of the above-described Figs. 10A to 10C may be applied, or the dither coefficient of Fig. 5 may be used.

First, when a process is started in step 120, it progresses to step 121 and initializes, and dither amount 0 is added and subtracted with dither amount DL = 0. That is, in step 121, the dither amount is not added or subtracted. Next, the flow advances to step 122 to detect the motion amount MV, and then proceeds to step 123 to compare the motion amount MV and the determination threshold value TD.

If it is determined in step 123 that the motion amount MV is smaller than the determination threshold value TD, the process proceeds to step 124 where the calculated motion amount MVC = 0, and the process proceeds to step 126. On the other hand, if it is determined in step 123 that the movement amount MV is equal to or larger than the determination threshold value TD, the flow advances to step 125 to calculate the calculation movement amount MVC = m x MV, and proceeds to step 126. Here, m is a proportional coefficient of the motion amount MV and the calculation motion amount MVC.

In step 126, dither amount DL = DK × MVC is calculated, and dither amount DL is further added and subtracted. The output signal MP of the motion adaptive dither circuit 205 is supplied to the SF coding circuit 40 as the output signal MP of the path (main path) 20.

In the flowchart of Fig. 17, when the relationship between the motion amount MV and the calculation motion amount MVC is in Fig. 12D, the calculation of the calculation motion amount MVC in step 125 is obtained by MVC = m × (MV-TD).

FIG. 18 is a flowchart showing an example of processing in the multi-gradation signal processing circuit as the third embodiment of the image display device according to the present invention shown in FIG. 13, for explaining the processing of the main path 20. Here, as the dither coefficient DK, any one of the dither coefficients of FIGS. 10A to 10C or 5 described above may be applied, and the relationship between the motion amount MV and the calculation motion amount MVC is any one of FIGS. 12A to 12D. You may.

First, when the process is started in step 130, the process proceeds to step 131 for initialization, and the dither amount calculation circuit 58 (see FIG. 11) sets the dither amount DL = 0 and outputs the sub path determination circuit 301. Set the signal (path determination signal) PSW to "0". Next, the flow advances to step 132 to add or subtract the dither amount DL, and the sub path switch 302 selects the output signal MP of the main path 20.

In step 133, the motion amount detecting circuit 50 detects the motion amount MV, and in step 134, the level detecting circuit 300 detects the level amount LV, and proceeds to step 135 to determine whether the level amount LV is zero. Determine whether or not.

In step 135, if the level amount LV is determined to be zero or in step 135 it is determined that the level amount LV is not zero, and in step 136 it is determined that pMV + qLV is smaller than SPsel, the process proceeds to step 139, respectively, and the motion amount MV is determined. And a predetermined threshold (decision threshold) TD are compared. On the other hand, if it is determined in step 135 that the level amount LV is not 0, and it is determined in step 136 that pMV + qLV is equal to or greater than SPsel, the flow proceeds to step 137. Here, the operation of step 136 may be pMV + LV.

The determination of whether the level amount LV in step 135 is zero is performed in the sub path determining circuit 301. In addition, p and q in step 136 are coefficients for taking the respective balances when calculating the motion amount MV and the level amount LV, and SPsel is a determination threshold value. Here, a large pMV + qLV indicates a gradation in which the pseudo-contour tends to be large due to the large amount of motion MV. In this case, the sub path switch 302 selects the output SP of the sub path 10.

In step 137, the dither amount DL is calculated, and the sub path determination circuit 301 outputs the path determination signal PSW of &quot; 1 &quot;, and then proceeds to step 138 to add and subtract the dither amount DL. The path switch 302 selects the output signal SP of the sub path 10 and returns to step 133. That is, in step 138, the sub path is selected by the sub path switch 302, so that the dither switching circuit 203 does not have any influence in the end. In addition, since the determination of whether or not the level amount LV in step 135 is 0 is not meaningful even when switching to the subpath 10 in the case of the gradation in which the pseudo contour does not come out no matter how large the movement amount MV is (the sub-number of gradations is generally low). This is to prevent the output signal SP of the sub path 10 from being selected when the level LV is 0, since switching to the path 10 causes a large amount of granular noise and degrades image quality.

If it is determined in step 139 that the movement amount MV is equal to or larger than the determination threshold value TD, the flow advances to step 13A to perform the calculation of the dither amount DL, and the sub path determination circuit 301 outputs the path determination signal PSW of "0". Further, the process proceeds to step 13B, where the dither amount DL is added and subtracted, and the sub path switch 302 selects the output signal MP of the main path 20 and returns to step 133.

On the other hand, if it is determined in step 139 that the movement amount MV is smaller than the determination threshold value TD, the process proceeds to step 13C, where the dither amount DL = 0, and the sub path determination circuit 301 sends the path determination signal PSW of "0". The output proceeds to step 13D, where the dither amount DL is added and subtracted, and the sub path switch 302 selects the output signal MP of the main path 20 and returns to step 133.

Thus, the output signal SP of the sub path 10 in pixel units, the output signal MPD in which dither is added and subtracted in the main path 20, and the three output signals MPL in which the dither is not added and subtracted in the main path 20. By selecting and switching one of them based on the motion amount MV, the level amount LV, and the dither coefficient DK, the pseudo contour can be reduced by spreading and modulating and dispersing it around the place where the pseudo contour is generated. Since it spreads and modulates based on the amount of motion MV, it is possible to control the intensity of generation of pseudo contours recognized by a person so that the speed at which the person is following the moving object, that is, the faster the speed of the moving object, is recognized as stronger. By adjusting the dither amount in accordance with the moving speed or the amount of motion, overmodulation or lack of modulation can be avoided.

Fig. 19 is a block diagram showing still another example of the path (main path) 20 in the multi-gradation signal processing circuit as the fourth embodiment of the image display device according to the present invention.

As can be clearly seen from the comparison between FIG. 19 and FIG. 3 described above, the arrangement of the error diffusion circuit 201, the dither circuit 202, the dither switching circuit 203, and the dither switching determination circuit 204 can be replaced. That is, in the fourth embodiment, the error diffusion circuit 201 provided immediately after the gain control circuit 200 in FIG. 3 is provided behind the dither switching circuit 203.

20 is a block diagram showing an example of the multi-gradation signal processing circuit 3 as the fifth embodiment of the image display device according to the present invention. In FIG. 20, reference numeral 10 denotes a sub path, 21 a main path, 22 a diffusion path, 31 a path switch circuit, 40 an SF coding circuit, and 50 a motion detection circuit.

As can be clearly seen from the comparison between FIG. 20 and FIG. 13 described above, the multi-gradation signal processing circuit 3 of the fifth embodiment has a subpath 10, a main path 21, and a diffusion path 22 for each primary color. The output of any one of the sub path 10, the main path 21, and the diffusion path 22 is selected by the path switch circuit 31 and supplied to the SF encoding circuit 40. Here, the sub path 10 is for displaying the input image signal at a predetermined gradation level (for example, a gradation level less than the gradation level of the input image signal), and the main path 21 actually displays the input image signal. Can be displayed in gradation level.

The sub path 10 has the same configuration as the sub path 10 shown in FIG. 13 and outputs a signal SP. The main path 21 receives the input image signal and outputs the signal MPG to the diffusion path 22, and simultaneously outputs the signal MPL to the path switch circuit 31. The motion detection circuit 50 also has the same configuration as the motion detection circuit 50 shown in Fig. 13 and outputs a motion amount MV.

The diffusion path 22 receives the output signal MPG of the main path 21 and the output signal (movement amount) MV of the motion detection circuit 50, and outputs a signal MPD subjected to the diffusion process according to the motion amount MV. The path switch circuit 31 outputs the output signal SP of the sub path 10, the output signal MPL of the main path 21, or the output signal of the diffusion path 22 according to the motion amount MV detected by the motion amount detection circuit 50. Any one of the MPDs is selected and output as the signal PSO to the SF encoding circuit 40. The SF encoding circuit 40 also has the same configuration as the SF encoding circuit 40 shown in FIG.

FIG. 21 is a block diagram illustrating an example of the main path 21 in the multi-gradation signal processing circuit shown in FIG. 20.

As can be clearly seen in FIG. 21, the main path 21 includes a gain control circuit 200 and an error diffusion circuit 201, and the output signal MPG of the gain control circuit 200 is supplied to the diffusion path 22. The output signal MPL of the error diffusion circuit 201 is supplied to the pass switch circuit 31.

FIG. 22 is a block diagram illustrating an example of a path switch circuit 31 in the multi-gradation signal processing circuit shown in FIG. 20.

As shown in FIG. 22, the path switch circuit 31 is provided with the level detection circuit 300, the path switch determination circuit 303, and the path switch circuit 304. As shown in FIG. The level detection circuit 300 has the same function as the level detection circuit 300 shown in FIG. 13, and outputs the level amount LV to the path switching determination circuit 303 based on the output signal MPL of the error diffusion circuit 201. do. The path switching determination circuit 303 is a control signal for switching paths in the path switching circuit 304 based on the level LV and the motion amount MV from the motion detection circuit 50 from the level detection circuit 300. Output the PSW. Then, the path switching circuit 304 outputs the output signal SP of the input sub path 10, the output signal MPL of the main path 21, or the diffusion path 22 according to the output signal PSW of the path switching determination circuit 303. Any one of the output signals MPD is selected and output to the SF encoding circuit 40 as a signal PSO.

That is, the values of the output signal PSW of the path switching determination circuit 303 are "0", "1" and "2", and the path switching circuit 304 is the main path 21 when the value of PSW is "0". Select the output signal MPL of &quot; 1 &quot;, and select the output signal MPD of the diffusion path 22 when the value of PSW is &quot; 1 &quot;, and output the signal SP of the subpath 10 when the value of PSW is &quot; 2 &quot; Choose.

FIG. 23 is a block diagram showing an example of a diffusion path 22 in the multi-gradation signal processing circuit shown in FIG.

As shown in FIG. 23, the diffusion path 22 includes an error diffusion circuit 201 and a motion adaptive dither circuit 205. Here, the error diffusion circuit 201 has the same function as the error diffusion circuit 201 in the main path 21 described above. The motion adaptation dither circuit 205 calculates the dither amount DL based on the motion amount MV which is the output of the motion detection circuit 50, and adds and subtracts this dither amount DL to the error diffusion circuit 201 signal to signal MPD. Outputs In addition, the motion adaptation dither circuit 205 can also be configured as the dither circuit 202 described above (for example, see FIG. 3 or FIG. 19).

FIG. 24 is a flowchart showing an example of processing in the multi-gradation signal processing circuit as the fifth embodiment of the image display device according to the present invention shown in FIG. Here, as the dither coefficient DK, any one of the dither coefficients of FIGS. 10A to 10C or 5 described above may be applied, and the relationship between the motion amount MV and the calculation motion amount MVC is any one of FIGS. 12A to 12D. You may.

First, when the process is started in step 240, the process proceeds to step 241 to perform initialization, and the dither amount calculation circuit 58 sets dither amount DL = 0, and the path switching determination circuit 303 determines the determination signal of "0". The PSW outputs "0". Next, the process proceeds to step 242 where the dither circuit 53 adds and subtracts the dither amount DL, and the path switching circuit 304 selects the output signal MPL of the main path 21.

In step 243, the motion amount detecting circuit 50 detects the motion amount MV, and in step 244, the level detecting circuit 300 detects the level amount LV, and the flow proceeds to step 245 to determine whether or not the level amount LV is zero. Determine.

If it is determined in step 245 that the level amount LV is zero, the flow proceeds to step 24C. In addition, if it is determined in step 245 that the level amount LV is not zero, in step 246 it is determined that pMV + qLV is not SPsel or greater, and in step 249 it is determined that pMV + qLV is not SPsel2 or greater (pMV + qLV <SPsel2 <). SPsel), the process proceeds to step 24C. Here, p and q in step 246 are coefficients for achieving respective balances when calculating the motion amount MV and the level amount LV, and SPsel and SPsel2 are determination threshold values. Further, there is a relationship of SPsel > SPsel2 between the decision thresholds SPsel and SPsel2.

Specifically, for example, when the movement amount MV is a value of 0 to 15 and the level amount is a value of 0 to 5 as in the conversion data shown in FIG. 5, p = 1 and q = 3, pMV and qLV The maximum value acquired by D is the same, and the operation balance of the movement amount and the level amount is the same in the path switching determination circuit 303. When p = 1 and q = 2, the value acquired by pMV becomes larger than the value obtained by qLV, so that the path switching decision circuit 303 makes the determination of the motion amount.

Then, at step 24C, the dither amount DL = 0, the path switching determination circuit 303 outputs the determination signal PSW of "0", proceeds to step 24D, and adds and subtracts the dither amount DL, and passes. The switching circuit 304 selects the output signal MPL of the main path 21 and returns to step 243.

In addition, if it is determined in step 245 that the level amount LV is not zero, and in step 246 it is determined that pMV + qLV is equal to or greater than SPsel (SPsel ≦ pMV + qLV), the process proceeds to step 247. Here, the fact that pMV + qLV is equal to or greater than SPsel (SPsel ≦ pMV + qLV: pMV + qLV is large) indicates a gradation in which pseudo contours tend to be large due to the large amount of motion MV. In the case of gray scales where the movement amount MV is large and pseudo contours are likely to come out, the process proceeds to step 247 to perform a dither amount DL operation, and the path switching determination circuit 303 outputs the determination signal PSW of "2". In addition, the process proceeds to step 248 to add or subtract the dither amount DL, and at the same time, the path switching circuit 304 selects the output signal SP of the sub path 10 and returns to step 243. In addition, when the output signal SP of the subpath 10 is selected like step 248, even if the dither amount DL is added or subtracted, there is no influence.

In addition, if it is determined in step 245 that the level amount LV is not 0, and if it is determined in step 246 that pMV + qLV is not SPsel or higher, the process proceeds to step 249. However, if it is determined in step 249 that pMV + qLV is SPsel2 or higher ( SPsel2 ≦ pMV + qLV <SPsel), the process proceeds to step 24A. In step 24A, while performing the dither amount DL calculation, the path switching determination circuit 303 outputs the determination signal PSW of "1", and proceeds to step 24B to perform the addition and subtraction of the dither amount DL, and the path switching circuit. 304 selects the output signal MPD of the diffusion path (dither processing path) 22 and returns to step 243.

In the above, the determination of the level amount 0 in step 245 is meaningless even when switching to the sub path or the dither processing path in the case of the gray level in which the pseudo contour does not come out no matter how much the motion amount (when the movement is small, the sub number is small. When switching to a path, there is more granular noise, or when switching to a dither processing path, the shape of the dither becomes noticeable and degrades image quality). When the level is 0, the sub path and the dither processing path are not selected. Thus, in the fifth embodiment, the dither amount DL is determined based on the motion amount MV, and the main path, subpath or dither processing path (spreading path) is switched based on the motion amount MV and the level amount LV. have.

As described with reference to Figs. 20 to 24, the image display device of the fifth embodiment is configured to perform level detection based on the output signal MPL of the error diffusion circuit. The image display device of the third embodiment shown in 18 performs level detection on the basis of the output signal MP which has undergone error diffusion processing and dither processing, and level detection differs depending on the dither amount DL to be added and subtracted, but both are pseudo contours. The image quality of the video display can be improved by dispersing the image into surrounding pixels.

FIG. 25 is a block diagram illustrating a modification of the spread path in the multi-gradation signal processing circuit shown in FIG. 20.

As can be clearly seen from the comparison between FIG. 25 and FIG. 21, the diffusion path 22 of the present modification includes a dither circuit 202 and an error diffusion circuit 201, and is configured to perform error diffusion after dither processing. Here, it goes without saying that the dither circuit 202 can also be configured as the motion adaptive dither circuit 205 shown in FIG. 23, for example.

By the way, since it is hard to notice that a pseudo contour is weakly generated in the periphery rather than focusing on one place and generating a pseudo contour, the sub path 10 is set to 1 in the main path 20 (21). By inserting at pixel intervals, the pseudo contour is widely generated, but weakly generated, so that it is not recognized as a pseudo contour.

Specifically, for example, in an image display device having a 1024-dot 42-inch screen size, a pseudo contour starts to be recognized when the number of horizontal pixels moves about 4 dots per field in the horizontal direction, so that the moving speed is increased. Therefore, pseudo contours are also strongly recognized. That is, in the case of an image moving slowly, the pseudo contour is less recognized and weak even if it is recognized. In this case, since the insertion of the subpath in the path switching method has a small number of gradations, the granular noise of the subpath becomes prominent, and the hatch-shaped noise due to the dither becomes prominent even when the dither coefficient is increased by the dither method. Therefore, in the case of a video moving slowly, it is preferable to control the dither coefficient by the dither method so that the subpath is not selected.

On the contrary, in the case of fast moving images, even if the ratio (frequency) of selecting the sub-path is increased by the path switching method, the granular noise is not noticeable, but pseudo contours are recognized beyond the pseudo contour reduction ability by the path switching method. Since the strength becomes stronger, the pseudo contour reduction effect is weakened as a result. Similarly, the pseudo contour reduction effect by the dither method is limited even if the dither coefficient is increased. Therefore, in the case of a fast moving image, the combination of the dither method and the path switching method is preferable because the pseudo contour reduction capability is improved. Therefore, it is better to gradually change the dither coefficient of the dither method or the ratio of inserting the subpath of the path switching method in accordance with the moving speed.

As mentioned above, of course, this invention can also be realized if there is a circuit for every primary color signal also about RGB primary colors. In addition, the application of the present invention is not limited to the plasma display device. In addition, although the weight of the subfield in this invention may be a weight of data, it may be a weight of brightness.

INDUSTRIAL APPLICABILITY The present invention can be widely applied to an image display apparatus including a plasma display apparatus, and is used as a display apparatus such as a personal computer or a workstation, a flat wall TV, or an apparatus for displaying advertisements or information. It can be applied to an image display device.

Claims (61)

delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete An image display apparatus which divides one field into a plurality of weighted subfields, and combines the plurality of subfields to perform multi-gradation display on a display panel. A main path for generating a signal having a predetermined number of gradations from an input image signal, A sub path for generating a signal having a smaller number of gradations than the main path, A diffusion processing path for generating a signal subjected to diffusion processing on the input image signal; A path switch circuit for switching and outputting any one of a generation signal of the main path, a generation signal of the subpath, and a generation signal of the diffusion processing path; A motion detection circuit for detecting an area moving between a current field and a field before the current field from the input image signal, and outputting a motion amount which is a moving amount; A level detecting circuit for detecting the level amount of the intensity of the pseudo contour when a moving image pseudo contour is generated by the main path; A path switching determination circuit for comparing the detected motion amount and the detected level amount with predetermined setting values, and determining a gradation having a strong pseudo outline generating intensity in a moving image area; A path switching circuit for switching the path switch circuit to any one of an output of the main path, an output of the sub path, or an output of the diffusion processing path, based on a determination result of the path switching determination circuit; A diffusion coefficient generation circuit for generating a diffusion coefficient depending on the gradation of the input image signal for calculating the amount of diffusion for spreading pseudo contour noise to the surroundings; A diffusion amount calculating circuit for calculating a diffusion amount based on the motion amount and the diffusion coefficient; A diffusion circuit for performing a diffusion process with the diffusion amount calculated by the diffusion amount calculation circuit; An image display apparatus characterized by reducing the pseudo contour by controlling the path switching circuit and the diffusion amount. The method of claim 28, The path switching determination circuit includes a first set value and a second set value smaller than the first set value, and selects the sub path when the diffusion amount calculated by the diffusion amount calculating circuit is equal to or larger than the first set value. And the diffusion process path is selected when the value is smaller than the first set value and is equal to or larger than the second set value, and the main path is selected when the value is smaller than the second set value. . The method of claim 28, And said diffusion circuit is a dither. delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete A main path for dividing one field into a plurality of weighted subfields, combining the plurality of subfields to perform multi-gradation display on a display panel, and generating a signal having a predetermined number of tones from an input image signal; A sub path for generating a signal having a smaller gradation number, a diffusion processing path for generating a signal subjected to diffusion processing on the input image signal, a generation signal for the main path, a generation signal for the sub path, or the diffusion processing path A driving method of an image display device having a path switching step of switching and outputting any one of generated signals, A motion detection step of detecting an area moving between a current field and a field before the current field from the input image signal, and outputting a motion amount which is a moving amount; A level detecting step of detecting a level amount of the intensity of the pseudo contour when a moving image pseudo contour is generated by the main path; A path switching determination step of comparing the detected motion amount and the detected level amount with predetermined setting values to determine a gradation having a strong pseudo outline generating intensity in a moving image area; A path switching step of switching the path switching step to any one of an output of the main path, an output of the sub path, or an output of the diffusion processing path based on the determination result of the path switching determination step; A diffusion coefficient generating step of generating a diffusion coefficient depending on the gradation of the input image signal for calculating a diffusion amount for diffusing pseudo contour noise into the surroundings; A diffusion amount calculating step of calculating a diffusion amount based on the motion amount and the diffusion coefficient; A diffusion step of performing a diffusion process with the diffusion amount calculated by the diffusion amount calculation step, And controlling the path switching step and the diffusion amount to reduce pseudo contours. The method of claim 58, The path switching determination step includes a first set value and a second set value smaller than the first set value, and when the diffusion amount calculated by the diffusion amount calculation step is equal to or greater than the first set value, the sub path is selected. And the diffusion process path is selected when the value is smaller than the first set value and is equal to or larger than the second set value, and the main path is selected when the value is smaller than the second set value. Method of driving. The method of claim 58, And the diffusion step performs dither diffusion. An image display apparatus which divides one field into a plurality of weighted subfields, and combines the plurality of subfields to perform multi-gradation display on a display panel. A main path for generating a signal having a predetermined number of gradations from an input image signal, A sub path for generating a signal having a smaller number of gradations than the main path, A diffusion processing path for generating a signal subjected to diffusion processing on the input image signal; A path switch circuit for switching and outputting any one of a generation signal of the main path, a generation signal of the subpath, and a generation signal of the diffusion processing path; A motion detection circuit for detecting an area moving between a current field and a field before the current field from the input image signal, and outputting a motion amount MV which is a moving amount; And a level detecting circuit for detecting the level amount LV of the intensity of the pseudo contour when a moving image pseudo contour is generated by the main path, The diffusion treatment pass, A diffusion coefficient generation circuit for generating a diffusion coefficient depending on the gradation of the input image signal for calculating the amount of diffusion for spreading pseudo contour noise to the surroundings; A diffusion amount calculation circuit for calculating a diffusion amount based on the motion amount MV and the diffusion coefficient; A diffusion circuit for performing a diffusion process with the diffusion amount calculated by the diffusion amount calculation circuit; The pass switch circuit, When the level amount LV is 0, the main path is selected. If the level amount LV is not 0 and the value N = pMV + qLV (where p and q are coefficients) that depends on the level amount LV and the motion amount MV is smaller than a first predetermined value, the main path is determined. Select If the level amount LV is not 0 and the value N is greater than or equal to the first predetermined value and smaller than the second predetermined value, the diffusion processing path is selected; And the sub path is selected when the level amount LV is not 0 and the value N is equal to or larger than the second predetermined value.

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