JPH10319904A - Multi-level picture display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable reduce so-called dynamic picture pseudo contour in a low luminance part or an intermediate luminance part where specifically accurate gradation expression is required. SOLUTION: Sub-fields are classified to a first sub-field group consisting of sub-fields in which luminance weight is the prescribed value or more and a second sub-field group consisting of residual sub-fields, sub-fields of the maximum L-1 pieces out of sub-fields of L pieces belonging to the first sub-fields group are arranged continuously, at least one sub-field is arranged between plural sub-fields belonging to the second sub-field group. Also, as ON-control of a sub-field being adjacent a sub-field having the largest luminance weight is suppressed and coded, occurrence of dynamic picture pseudo contour is suppressed low, and picture reduced in the blurring of dynamic picture can be displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device which displays a multi-gradation display by dividing one field of an image into a plurality of sub-field images and displaying the image. The present invention relates to a multi-gradation image display device which displays images with improved gradation disturbance.

[0002]

2. Description of the Related Art Conventionally, when a gray scale display is performed using a display device, such as a plasma display device, which divides and displays one field of an image into a plurality of sub-field images and displays the image, for example, a plasma display device. It is known that so-called pseudo-contour-like gradation disturbance occurs in moving image display.

[0003] The occurrence of a pseudo contour when displaying a moving image will be described with reference to FIG. FIG. 11 shows a state in which an image having a pattern in which two levels of level 15 and level 16 are adjacent to each other (an example is shown in FIG. 12) is displayed, and the state in which the adjacent pattern follows a pattern that has been translated. Is shown.

In a display device which divides one field of an input image into a plurality of subfields and performs gradation display, when a still image is displayed, the average luminance of one field of the observed image is AA in FIG. '
The gradation display is performed correctly.

On the other hand, when a moving image is displayed, depending on the direction of movement of the line of sight, the area between BB ′ in FIG.
The emission integral during C 'is observed. Between BB ', the combined value of each bit is approximately 0, and the sum of each bit between CC' is approximately 31. Thus, level 1
When two levels 5 and 16 are observed adjacent to each other, the luminance level observed in the level change portion is significantly disturbed by the motion of the image as shown in FIG.

Although FIG. 11 illustrates that light emission is continuously performed with a predetermined width for each subfield, in an actual plasma display, each subfield is assigned a luminance weight. Although it is composed of a set of pulsed light emission of the number of times, the gradation disturbance at the time of displaying a moving image is essentially the same.

As described above, since the halftone is expressed by integrating the luminance of each subfield in the time direction, if the line of sight moves in a moving image or the like, a position different from the original pixel position with the lapse of time. Will be integrated, and the halftone display will be greatly disturbed. Since this halftone disturbance is recognized so that a false outline appears in the image, it is hereinafter referred to as a moving image pseudo outline.

[0008] As an attempt to reduce the false contour of a moving image,
In a conventional image display device, an attempt has been made to reduce the halftone display disturbance in moving image display by dividing the luminance weight of a subfield corresponding to a plurality of higher-order bits and further distributing and configuring the luminance. I have.

FIG. 13 shows a subfield structure in the moving image pseudo contour reducing method according to the conventional method.
8-bit gradation using 0 subfield, that is, 25 bits
It is intended to display six gradations. The luminance weighting of each subfield is 48, 48, 1, 2, 4,.
8, 16, 32, 48, and 48. The luminance weight of the upper 2 bits 64 and 128 of the original input image signal is 4
Divided and distributed at both ends of the subfield, the weight of the most significant bit is reduced to minimize the occurrence of halftone disturbance, and a subfield with a large weight is placed at the beginning and end of the subfield. By distributing the images, blur is generated in the image observed when the moving image is displayed, and the pseudo contour of the moving image is made inconspicuous.

[0010]

As shown in FIG.
In a conventional image display device, subfields having the largest luminance weight are arranged in a distributed manner in the first half and the second half of one field. FIG. 13 shows an example of on / off control of each subfield with respect to the input image signal level.

For example, when the signal level of the input image signal is 14
As the number increases from 3 to 144, the number of “luminance weighting = 48” subfields that are turned on increases from 2 to 3. At this time, although the level of the input image signal is slightly increased by 1, the subfield having the largest luminance weight is turned on at a position temporally separated.

For this reason, when the same phenomenon as that of FIG. 11 is observed, that is, when a moving image is observed with the sight line of sight, FIG.
As shown in (a) and FIG. 13 (b), strong gradation disturbances differing depending on the direction of the line of sight occurred, and the suppression of the false contour of the moving image was insufficient. The four subfields of “luminance weight = 48” arranged at both ends apart form a total of 192 luminance weights, and occupy most of the total luminance weights. Therefore, when the image is displayed and the line of sight follows,
The observed image is a composition of image components that are temporally separated, and as a result, the moving image portion is blurred.
For this reason, there is also a problem that image quality is deteriorated such that moving fine characters are duplicated and cannot be read.

[0013]

In order to solve the above-mentioned problems, a multi-tone image display device of the present invention converts one field of an input signal into a plurality of M sub-fields having a predetermined luminance weight. An image display device which divides and performs multi-tone display by ON control or OFF control of each of the subfields, wherein a luminance weight of each of the plurality of M subfields is equal to or more than a predetermined value Are defined as a first subfield group, the remaining ML subfields are defined as a second subfield group, and a maximum of L among the subfields belonging to the first subfield group is defined as -1 subfields are arranged in a continuous order, and at least one of the subfields belonging to the first subfield group
The plurality of subfields are arranged so as to be sandwiched between a plurality of subfields belonging to the second subfield group.

Further, in the multi-tone image display device according to the present invention, the sum of the luminance weights of the second sub-field group sandwiching the sub-fields belonging to the first sub-field group may be determined before and after the position where the sandwiching is performed. It is characterized by being made substantially equal.

Further, the multi-tone image display device of the present invention is characterized in that the luminance weights of the respective sub-fields belonging to the first sub-field group are arranged in the order of monotonically increasing or decreasing. .

Also, in the multi-tone image display device according to the present invention, the luminance weight of each subfield belonging to the first subfield group may be different from the luminance weight of each subfield belonging to the second subfield group. Is an integral multiple of a value obtained by increasing the luminance weight by one.

Further, in the multi-tone image display device according to the present invention, when the on-control of each of the first sub-fields displays the signal level of the input signal in ascending order, the on-control of the sub-fields is performed. When the subfield having the largest luminance weight is first selected and turned on, the on-control of the subfield adjacent to the subfield having the largest luminance weight among the on-controlled subfields is suppressed to a predetermined luminance display. Is controlled so as to select and display a subfield in which the subfield is enabled.

According to the present invention, one field of an input signal is divided into a plurality of M subfields having a predetermined luminance weighting, and multi-gradation display is performed by on-control or off-control of each subfield. In the image display device, the plurality of L subfields, each of which has a luminance weight equal to or more than a predetermined value, among the plurality of M subfields, are defined as a first subfield group, and the remaining M− The L subfields are defined as a second subfield group, and a maximum of L-1 subfields among the subfields belonging to the first subfield group are arranged in a continuous order. The light emission is relatively concentrated, and when the input signal level changes continuously, the light emission pattern of each subfield becomes extremely small. Can vary is suppressed, it is possible to suppress the so-called dynamic false contour over a wide range of input signal levels.

Further, since subfields having a large luminance weight are concentrated, when a moving image is displayed and the line of sight follows, the occurrence of image blurring in the observed image is suppressed, and fine moving characters are displayed. Can be suppressed, and the image quality can be prevented from being unreadable.

According to the present invention, at least one of the sub-fields belonging to the first sub-field group is provided.
Since the subfields are arranged so as to be sandwiched between a plurality of subfields belonging to the second subfield group, a so-called moving image pseudo-contour is obtained particularly in a low-luminance or middle-luminance portion where accurate gradation expression is required. Can be reduced.

Further, according to the present invention, since the luminance weights of the sub-fields belonging to the first sub-field group are arranged in the order of monotonically increasing or monotonically decreasing, the luminance is relatively low at low luminance. The predetermined luminance can be expressed by using only the adjacent subfields having a small luminance weight, and it is possible to suppress and display the moving image pseudo contour at low luminance where the moving image pseudo contour is particularly conspicuous.

Further, according to the present invention, the luminance weight of each subfield belonging to the first subfield group is determined by summing the luminance weight of each subfield belonging to the second subfield group. Since it is characterized in that it is an integral multiple of 1 increment, the details of the level of the input signal are expressed by ON control or OFF control of each subfield belonging to the second subfield group, and the level of the input signal is Can be expressed by on-control or off-control of each subfield belonging to the first subfield group, and detailed gradation display can be performed without loss over the previous range of the input signal.

According to the present invention, when the signal level of the input signal is displayed in ascending order in the on-control of each of the first sub-fields, the luminance weight is the largest among the on-controlled sub-fields. When a subfield is first selected and turned on, a subfield in which a predetermined luminance display is possible by suppressing on control of a subfield adjacent to the subfield having the largest luminance weight among the subfields that are on-controlled. Fields are controlled to be selected and displayed, and at the signal level change point where it is relatively easy to generate moving image false contours, the sub-field with the highest luminance weight among the sub-fields that are on-controlled first When selected and turned on, the subfield having the largest luminance weight among the subfields that are on-controlled. By avoiding the on-control of the subfield adjacent to as much as possible, instead, selecting a distant subfield and displaying the predetermined luminance, the pseudo contour of the moving image is equivalently partially canceled, and a good moving image display is achieved. It can be carried out.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A multi-tone image display device according to the present invention (claims 1, 6 to 9) divides one field of an input signal into a plurality of M subfields having a predetermined luminance weight. In the image display apparatus which performs multi-tone display by ON control or OFF control of each of the sub-fields, a plurality of M sub-fields each having a luminance weight equal to or more than a predetermined value are provided. Let L subfields be a first subfield group and the remaining ML subfields be a second subfield group, and at most L-1 subfields among the subfields belonging to the first subfield group Are arranged in a continuous order, and at least one of the subfields belonging to the first subfield group is the second subfield. It is a multi-tone image display apparatus being characterized in that disposed by sandwiching a plurality of sub-fields belonging to the field group.

For this reason, since the approximate part of the luminance information of the image is represented by the light emission of the continuously arranged subfields, when the level of the input signal continuously changes, the light emission of each subfield is changed. Since the pattern is originally concentrated, the relative light emission position is suppressed from extremely fluctuating, and so-called moving image false contour can be suppressed over a wide range of the input signal level. In addition, since the subfields with large luminance weights are concentrated, when a moving image is displayed and the line of sight follows, the occurrence of image blurring in the observed image is suppressed, and the moving fine characters are doubled. , It is possible to prevent the image quality from becoming unreadable.

Further, in the multi-tone image display device according to the present invention (claims 2 to 6 to 9), the sum of the luminance weights of the second sub-field group sandwiching the sub-field belonging to the first sub-field group can be reduced. Since the arrangement is made substantially equal before and after the position where the sandwiching is performed, it is possible to reduce so-called moving image pseudo-contours, particularly in a low luminance or middle luminance portion where accurate gradation is required. .

Further, in the multi-tone image display device according to the present invention (claims 3 and 6 to 9), the order in which the luminance weights of the subfields belonging to the first subfield group are monotonically increasing or monotonically decreasing. The multi-tone image display device is characterized in that the image display device is arranged in the following manner. For this reason, at low luminance, a predetermined luminance can be expressed using only adjacent sub-fields having relatively small luminance weights. It can be suppressed and displayed.

Further, in the multi-tone image display device according to the present invention (claims 4 and 6 to 9), each subfield belonging to the first subfield group has a luminance weight corresponding to the second subfield group. Wherein the sum of the luminance weights of the respective sub-fields belonging to the sub-fields is an integer multiple of the luminance weight incremented by 1, and the details of the level of the input signal are described in the second sub-field. Control the on or off of each subfield belonging to the group, and the level of the input signal can be represented by the on or off control of each subfield belonging to the first subfield group; ON control or OFF control of each subfield can be easily performed.

Further, in the multi-tone image display device according to the present invention (claim 5), the on-control of each of the first sub-fields is as follows:
When the signal levels of the input signal are displayed in ascending order, when the subfield having the highest luminance weight among the subfields that are on-controlled is selected and turned on first, A multi-tone image display device, characterized in that on-control of a sub-field adjacent to a sub-field having a large luminance weight is suppressed and a sub-field capable of displaying a predetermined luminance is selected and displayed. , At a signal level change point which is said to be relatively easy to generate a false contour of a moving image,
As described above, when the subfield having the highest luminance weight among the subfields whose on-control is performed is first selected and turned on, it is adjacent to the subfield having the highest luminance weight among the on-controlled subfields. The on-control of the sub-field is avoided as much as possible, and instead, a distant sub-field is selected and the display of the predetermined luminance is performed. Therefore, the pseudo contour of the moving image is partially canceled, and a favorable moving image can be displayed.

(Embodiment 1) Embodiments of the present invention (claims 1 and 2) will be described below with reference to the drawings. In FIG. 2, 1 is an input signal, 2 is an A / D converter for converting the input signal into an 8-bit digital signal, 3 is 8
This is a subfield conversion circuit that rearranges an image signal represented by a digital signal of bits into a signal composed of ten subfields. 4 is a plasma display. The plasma display 4 is turned on or off.
Although the display device emits light in a quantitative manner, the brightness is expressed by the sum of the light emissions of ten subfields each having a predetermined number of times of light emission as a luminance weight, so that halftone display is possible.

In the multi-tone image display device configured as described above, the order of each subfield and each luminance weight are represented by the relationship shown in FIG. As shown in FIG. 1, in the multi-tone image display device of the present embodiment, one field of an input signal is divided into ten sub-fields, and six sub-fields each having a luminance weight of 16 or more. Subfields (brightness weights are 16, 16, 32, 4 respectively)
8, 48, 80);
Four subfields in which the luminance weight of each subfield is 8 or less (the luminance weights are 1, 2, 4, and 8 respectively)
, And one of the subfields belonging to the first subfield group (the subfield with a luminance weight of 16) is interposed between the second subfield groups. doing. That is, when the arrangement of the ten subfields is represented by using the luminance weight, the arrangement is such that 1, 2, 4, 16, 8, 16, 32, 48, 48, and 80.

The subfield conversion circuit 3 shown in FIG. 2 converts an input signal into a digital video signal obtained by A / D conversion and a subfield control signal, and performs control as shown in FIG. I have. In FIG.
Subfields marked "1" are "on",
A subfield described as “0” means that the field period is “off”.

Incidentally, the lower 4 bits of the digital video signal are used as they are for the on / off control of the second subfield group.

In the multi-tone image display device configured as described above, first, when the value of the digital video signal changes from 15 to 16, as shown below, the arrangement of the sub-fields to be turned on is as follows. Are averaged, so
The false contour of the moving image at the level change portion is suppressed.
Note that this portion has relatively low luminance, and a slight change in level is likely to cause a large change in hue, and it is extremely important to suppress the generation of a moving image false contour.

Subfield luminance weights: 1, 2, 4,
16, 8, 16, 32, 48, 48, 80 When level = 15: 1 1 1 1 1 1 0
0 0 0 0 When level = 16: 0 0 0 1 0 0
0 0 0 0 Also, as can be seen from the portion surrounded by the thick frame in FIG. 3, when the signal levels of the digital video signals are displayed in ascending order, the sub-field having the largest luminance weight among the sub-fields that are on-controlled. When first selected and turned on,
The on-control of the sub-field adjacent to the sub-field having the largest luminance weight among the on-controlled sub-fields is suppressed as much as possible, and a predetermined luminance weight is obtained by combining the sub-fields apart from each other.
For this reason, at a signal level at which a so-called moving image pseudo contour is likely to occur, the pseudo contour is compared with a sub field adjacent to the sub field having the largest luminance weight among the sub fields which are turned on and emits light when turned on. Can be suppressed.

FIG. 4 shows a conventional eight subfields, ie, luminance weights of 1, 2, 4, 8, 16, 32, 64, 1
The relative value of the moving image pseudo contour amount when the subfield configuration of No. 28 is used is shown. On the other hand, FIG. 5 shows a relative value of the moving image pseudo contour amount when the subfield configuration according to the embodiment of the present invention is used. These figures show the case where the movement of pixels per field is 12 pixels.
It is obtained by simulation. As can be seen from FIG. 4 and FIG. 5, by using 10 subfields and using the subfield conversion configured in the above-described configuration and order, the pseudo-moving image can be compared with the conventional 8-subfield method. The generation of the contour can be greatly suppressed.

(Embodiment 2) Hereinafter, an embodiment of the present invention (claim 8) will be described with reference to the drawings with respect to portions different from embodiment 1 of the present invention. In FIG. 6, reference numeral 1 denotes an input signal, 2 denotes an A / D converter for converting the input signal into an 8-bit digital signal, and 31 denotes an image signal represented by an 8-bit digital signal composed of 11 subfields. This is a subfield conversion circuit for rearranging the signals into the subfields. In the multi-tone image display device of the present embodiment, 8
Bit digital video signal is converted into a signal composed of 11 sub-fields,
To supply. The plasma display 4 is a display device that performs binary light emission of ON or OFF, and the brightness is expressed by the sum of the light emission of 11 subfields each having a predetermined number of light emission times as the brightness weight. Is made possible.

In the multi-tone image display device configured as described above, the order of each subfield and each luminance weight are represented by the relationship shown in FIG. As shown in FIG. 7, in the multi-tone image display device of the present embodiment, one field of the input signal is divided into 11 sub-fields, and each sub-field has a luminance weight of 16 or more. Subfield (the luminance weights are 16, 16, 32, 3 respectively)
2, 48, 48, 48) and four subfields (the luminance weights are 1, 2 and 4, respectively) in which the luminance weight of each subfield is 8 or less.
4, 8), and one of the sub-fields belonging to the first sub-field group (the sub-field of luminance weight = 16) is placed between the second sub-field group. It is arranged sandwiched between.

That is, when the arrangement of the eleven subfields is represented by using luminance weights, 1, 2, 4, 16, 8, 16, 32, 32, 48, and 4
8,48.

The subfield conversion circuit 31 shown in FIG. 6 converts an input signal into a digital video signal obtained by A / D conversion and a subfield control signal.
Is performed as shown in FIG. In FIG.
Subfields marked "1" are "on",
A subfield described as “0” means that the field period is “off”.

Incidentally, the lower 4 bits of the digital video signal are used as they are for the on / off control of the second subfield group.

In the multi-tone image display device configured as described above, first, when the value of the digital video signal changes from 15 to 16, the subfield arrangement as described above is performed. The suppression of the moving image pseudo contour at the level change portion is the same as in the first embodiment, and prevents a slight level change caused by the moving image pseudo contour from becoming a large change in hue, which is extremely effective. It is.

As can be seen from the portion surrounded by the bold frame in FIG. 8, when the signal levels of the digital video signals are displayed in ascending order, the subfield having the largest luminance weight among the subfields whose on-state is controlled first. When selected and turned on, the on-control of a subfield adjacent to the subfield having the largest luminance weight among the subfields that are on-controlled is suppressed as much as possible, and a predetermined luminance weight is set by combining distant subfields. I am trying to become. Therefore, at a signal level at which a so-called moving image pseudo contour is likely to occur, the pseudo contour can be canceled equivalently.

As described above, by using 11 sub-fields and using the above-described configuration and sub-field conversion, it is possible to greatly suppress the generation of a moving image false contour as compared with the related art.

(Embodiment 3) Hereinafter, an embodiment of the present invention (claim 9) will be described with reference to the drawings with respect to portions different from the embodiments 1 and 2.

In FIG. 9, 1 is an input signal, 2 is an A / D converter for converting the input signal into an 8-bit digital signal, and 32 is an image signal represented by an 8-bit digital signal in 12 subfields. Is a subfield conversion circuit that rearranges the signal into a signal composed of In the multi-tone image display device of the present embodiment, an 8-bit digital video signal is converted into a signal composed of 12 subfields and supplied to the plasma display 4. The plasma display 4 is a display device that performs binary light emission of ON or OFF. The luminance is expressed by the sum of the light emission of 12 subfields each having a predetermined number of light emission times as the luminance weight, and the halftone display is performed. Is made possible.

In the multi-tone image display device of the present embodiment, an 8-bit digital video signal is divided into 12 subfields and supplied to the plasma display 4. The plasma display 4 is a display device that performs binary light emission of ON or OFF. The luminance is expressed by the sum of the light emission of 12 subfields each having a predetermined number of light emission times as the luminance weight, and the halftone display is performed. Is made possible.

In the multi-tone image display device configured as described above, the order of each subfield and each luminance weighting are represented by the relationship shown in FIG. As shown in FIG. 10, in the multi-tone image display device of the present embodiment, one field of an input signal is divided into 12 sub-fields, and each sub-field has eight luminance weights of 16 or more. Subfield (the luminance weights are 16, 16, 3 respectively)
2, 32, 32, 48, 48) and four sub-fields (the luminance weights of which are 1 and 1 respectively) where the luminance weight of each sub-field is 8 or less.
2, 4 and 8), and one of the sub-fields belonging to the first sub-field group (the sub-field of luminance weight = 16) is assigned to the second sub-field group. It is arranged sandwiched between.

That is, when the arrangement of the eleven subfields is represented by using the luminance weight, 1: 2: 4: 16: 8: 16: 16: 32: 32: 3
The arrangement is such that 2:48:48.

Also in this embodiment, when the signal levels of the digital video signals are displayed in ascending order, when the subfield having the largest luminance weight is selected first from among the subfields whose on-state is controlled, this subfield is turned on. By suppressing on-control of a subfield adjacent to a subfield having the largest luminance weight among subfields that are on-controlled as much as possible and combining distant subfields to have a predetermined luminance weight, a so-called moving image is obtained. At signal levels where false contours are likely to occur,
The pseudo contour can be canceled equivalently.

As described above, by using 12 subfields and using the above-described configuration and the subfield conversion, it is possible to greatly suppress the generation of a moving image false contour as compared with the related art.

When one field of the input signal is divided into nine sub-fields and multi-gradation display is performed by on-control or off-control of each of the sub-fields, of the nine sub-fields, Brightness ratio of 16:
The subfield group of 32: 48: 64: 80 is the first
Of the remaining four subfields, a subfield group having a luminance weight ratio of 1: 2: 4: 8 is a second subfield group, and the nine subfield groups are luminance weighted. Is 1: 2: 4: 16: 8: 3
It is sufficient to arrange them in the order of 2: 48: 64: 80 or the reverse order.

[0053]

As described above, according to the multi-tone image display device of the present invention, the following effects can be obtained.

In the multi-tone image display device according to the present invention (claim 1), one field of the input signal is divided into M subfields, and the luminance weight of each subfield is equal to or greater than a predetermined value. Divided into a first subfield group consisting of a plurality of subfields and a second subfield group consisting of ML subfields in which the luminance weight of each subfield is equal to or less than a predetermined value. At least one of the subfields belonging to the subfield group of
Are arranged between the second sub-field groups, so that a so-called moving image false contour can be reduced particularly in a low luminance or middle luminance part where accurate gradation expression is required. become.

Further, since the subfields having a large luminance weight are concentrated, when a moving image is displayed and the line of sight follows, the occurrence of image blurring in the observed image is suppressed, and fine characters that move are displayed. Can be suppressed, and the image quality can be prevented from being unreadable.

Further, in the multi-tone image display device according to the present invention (claim 2), the sum of the luminance weights of the second subfield group that sandwiches the subfields belonging to the first subfield group is equal to Is substantially equal before and after the position where the image processing is performed, so that it is possible to reduce a so-called moving image false contour particularly in a low luminance or middle luminance part where accurate gradation expression is required.

Further, in the multi-tone image display device according to the present invention (claim 3), the luminance weights of the respective sub-fields belonging to the first sub-field group are arranged in an order in which the luminance weight increases or decreases monotonously. Therefore, at low luminance, a predetermined luminance can be expressed using only adjacent subfields having a relatively small luminance weight, and in particular, moving image pseudo-contours at low luminance where the moving image pseudo-contours are conspicuous. The occurrence can be suppressed and displayed.

Further, in the multi-tone image display device according to the present invention (claim 4), the luminance weight of each sub-field belonging to the first sub-field group may be different from the luminance weight of each sub-field belonging to the second sub-field group. Since the sum of the luminance weights of the sub-fields is an integral multiple of the luminance weight increased by 1, the level of the input signal is controlled by turning on or off each sub-field belonging to the second sub-field group. As a result, the level of the input signal can be roughly expressed by on / off control of each subfield belonging to the first subfield group, and on / off control of each subfield can be easily performed. Can be.

Further, in the multi-tone image display device according to the present invention (claim 5), when the subfield having the largest luminance weight is selected first from among the subfields which are controlled to be turned on, the multifield image display device is turned on. Since the on-control of the sub-field adjacent to the sub-field having the highest luminance weight among the controlled sub-fields is avoided as much as possible, instead, a distant sub-field is selected and a predetermined luminance is displayed. Partially canceled, good moving image display can be performed.

Further, the multi-tone image display device according to the present invention (claims 6 to 9) uses 9 to 12 subfields, and uses the above-described configuration and subfield conversion to achieve the conventional Compared with the driving method using eight subfields, the generation of a moving image pseudo contour can be significantly suppressed.

The effect of the present invention is not limited to the specific case shown in the embodiment described above, and various modifications such as increasing the number of subfields and reversing the order of subfields are possible. Needless to say, this is possible. Also, the encoding method for determining the correspondence between the digital video signal and the signal subjected to the subfield conversion is not limited to the method shown in this specification, and various modifications within the scope of the claims of the present invention are also possible. Of course it is possible.

[Brief description of the drawings]

FIG. 1 is a diagram showing subfield numbers and luminance weighting of each subfield in Embodiment 1 of the present invention.

FIG. 2 is a configuration diagram of a multi-tone image display device according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a method of on / off control of a subfield according to the first embodiment of the present invention;

FIG. 4 is a diagram showing a generation amount of a moving image false contour according to a conventional method using eight subfields.

FIG. 5 is a diagram showing a generation amount of a moving image pseudo contour according to the first embodiment of the present invention;

FIG. 6 is a configuration diagram of a multi-tone image display device according to a second embodiment of the present invention.

FIG. 7 is a diagram showing subfield numbers and luminance weighting of each subfield in Embodiment 2 of the present invention.

FIG. 8 is a diagram showing a method of on / off control of a subfield according to the second embodiment of the present invention.

FIG. 9 is a configuration diagram of a multi-tone image display device according to a third embodiment of the present invention.

FIG. 10 is a diagram showing subfield numbers and luminance weighting of each subfield in Embodiment 3 of the present invention.

FIG. 11 is a diagram showing a cause of generation of a false contour of a moving image.

FIG. 12 is a diagram showing an example of an image having two adjacent levels.

FIG. 13 is a view showing a moving image pseudo contour in a conventional example using 10 subfields.

[Explanation of symbols]

 Reference Signs List 1 input image signal 2 A / D converter 3 subfield conversion circuit 4 plasma display 31 subfield conversion circuit 32 subfield conversion circuit

Claims (9)

[Claims] 1. An image display device which divides one field of an input signal into a plurality of M subfields having a predetermined luminance weight, and performs multi-gradation display by ON control or OFF control of each subfield. Wherein, among the plurality of M subfields, a plurality of L subfields, each of which has a luminance weight equal to or greater than a predetermined value, as a first subfield group,
The remaining ML subfields are defined as a second subfield group, and a maximum of L-1 subfields among the subfields belonging to the first subfield group are arranged in a continuous order, Wherein at least one of the sub-fields belonging to the sub-field group is arranged to be sandwiched between a plurality of sub-fields belonging to the second sub-field group. 2. The method according to claim 1, wherein the sum of the luminance weights of the second subfield group sandwiching the subfields belonging to the first subfield group is substantially equal before and after the position where the sandwiching is performed. The multi-tone image display device according to claim 1. 3. The multi-tone image display device according to claim 1, wherein the luminance weights of the respective sub-fields belonging to the first sub-field group are arranged in a monotone increasing or monotonically decreasing order. . 4. A luminance weight of each subfield belonging to the first subfield group is an integer obtained by increasing a luminance weight of each subfield belonging to the second subfield group by one luminance weight. 2. The multi-tone image display device according to claim 1, wherein the number is doubled. 5. The on-control of each of the first sub-fields is such that when the signal levels of the input signals are displayed in ascending order, a sub-field having the largest luminance weight is selected first among the sub-fields which are on-controlled. When the sub-field is turned on, the sub-fields adjacent to the sub-field having the largest luminance weight among the sub-fields being on-controlled are suppressed from being turned on, and a sub-field capable of displaying a predetermined luminance is selected and displayed. 5. The multi-tone image display device according to claim 3, wherein the control is performed. 6. An image display device which divides one field of an input signal into nine sub-fields and performs multi-gradation display by on / off control of each of said sub-fields, wherein: In the field, set the ratio of the luminance weight to 1
A subfield group of 6: 32: 48: 64: 80 is a first subfield group, and the remaining four subfields are subfield groups having a luminance weight ratio of 1: 2: 4: 8. 2 sub-field groups, and the 9 sub-field groups have a luminance weight ratio of 1: 2: 4: 16:
5. An arrangement according to claim 1, wherein the arrangement is in the order of 8: 32: 48: 64: 80 or vice versa.
The multi-tone image display device according to any one of the above. 7. An image display device which divides one field of an input signal into ten subfields and performs multi-gradation display by ON control or OFF control of each of said subfields, wherein: In the field, set the ratio of the luminance weight to 1
A subfield group of 6: 16: 32: 48: 48: 80 is defined as a first subfield group, and the remaining four subfields have a luminance weight ratio of 1: 2: 4: 8. As a second subfield group,
The luminance weight ratios of the subfield groups are 1: 2: 4:
5. The multi-tone image display device according to claim 1, wherein the multi-gradation image display device is arranged so that the order is 16: 8: 16: 32: 48: 48: 80 or the reverse order. 8. An image display device which divides one field of an input signal into 11 sub-fields and performs multi-gradation display by ON control or OFF control of each of said sub-fields, wherein: In the field, set the ratio of the luminance weight to 1
A subfield group of 6: 16: 32: 32: 48: 48: 48 is defined as a first subfield group, and the remaining four subfields have a luminance weight ratio of 1: 2: 4: 8. The field group is defined as a second subfield group, and the eleven subfield groups have a luminance weight ratio of 1:
2: 4: 16: 8: 16: 32: 32: 48: 48: 4
The multi-tone image display device according to any one of claims 1 to 4, wherein the multi-gradation image display device according to any one of claims 1 to 4, wherein the multi-gradation image display device is arranged so as to have the order of (8) or the reverse order. 9. An image display device which divides one field of an input signal into twelve sub-fields and performs multi-gradation display by ON / OFF control of each of said sub-fields, wherein: In the field, set the ratio of the luminance weight to 1
A subfield group of 6: 16: 16: 32: 32: 32: 48: 48 is defined as a first subfield group, and the remaining four subfields have a luminance weight ratio of 1: 2: 4:
8 as a second subfield group, and the twelve subfield groups have a luminance weight ratio of:
1: 2: 4: 16: 8: 16: 16: 32: 32: 3
5. The multi-tone image display device according to claim 1, wherein the multi-tone image display device is arranged in the order of 2: 32: 48: 48: or the reverse order.