JP2000259127A - Gradational display method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To actualize the gradational display method which can prevent a moving picture from deteriorating in picture quality when subfields are used while suppressing an increase in cost. SOLUTION: When a 256-gradational display of one color is made, temporal segments 1 to 6 corresponding to time-division time zones of the color are set in one frame and each segment is composed of more subfield (sf); and segments 1 to 6 are increased continuously each time the gradations increase by 42 (or 43) so that subfields in the segments illuminate, and the subfields illuminate in each segment almost according to the binary notation so that the subfield ends in the segment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a plasma display panel (hereinafter referred to as a PDP (Plasma Display panel)) or a DMD (Digital Micromirror Device).
The present invention relates to a gradation display method of a display device using a so-called subfield method, which has a memory of values and displays a plurality of binary images weighted with a moving image having a halftone, respectively, in a temporal manner. .

[0002]

2. Description of the Related Art In a conventional so-called subfield method, an image having a halftone is displayed on a display device having a binary (on / off) memory effect, as disclosed in Japanese Patent Application Laid-Open No. 4-195087. It is used for
29 and 30 show examples of this display method. This is shown in FIG.
In this example, red, green, and blue are sequentially displayed using one DMD element and a rotating color filter as shown in FIG. 1 to display a color image and an 8-bit, 256-gradation television image.

In FIG. 31, 1 is a DMD element, 2 is a disk-shaped color filter, 3 is a lamp, and 4 is a projection lens. The DMD element 1 is an aggregate of minute mirrors,
The mirror is turned on (lit) at a very high speed depending on the video signal /
Display can be made by switching off (non-lighting).

In this conventional example, one image (one field) is composed of eight binary images (subfields). The time length of each subfield shown in FIG.
A weight corresponding to the luminance of one color when only the subfield is turned on is given. In the case of the configuration shown in FIG. 31, the mirror of the DMD is turned on (lit). Something that responds to time, or
This corresponds to the number of lighting pulses within this time length. In the example of FIG. 29 and FIG. 30, each subfield is “1”, “2”,
"4", "8", "16", "32", "64", "1"
28 "(luminance). That is, each subfield has a unit time length t,
“1”, “2”, “4”, “8”, “16”, “3”
2 "," 64 ", and" 128 "times.
As shown in FIG. 30, each pixel of the DMD displays a halftone by a combination of which subfield is turned on. For example, the luminance corresponding to “173” is a subfield number 8 with a weight of “128”, a subfield number 6 with a weight of “32”, a subfield number 4 with a weight of “8”, and a subfield with a weight of “4”. It is obtained by lighting each subfield of subfield number 1 with field number 3 and weight “1”. In the following description and each drawing, subfield number 1, subfield number 2, etc.
f "," 2sf ", etc.

[0005] In a still image, since the line of sight is substantially fixed, the addition of subfields is normally performed in each pixel, so that there is no deterioration in image quality. By adopting such a driving method, it is possible to perform gradation display even with an element such as a mirror that can take only two values of ON and OFF.

[0006]

However, in the above display method using the conventional subfield method, the literature (“Pseudo-contour noise seen in pulse-width modulation moving image display”): Television Society Technical Report, Vol. No.2, IDY95-21, pp.61-6
As shown in (6), there is a problem that a unique pseudo-contour-like noise is seen in a moving image and the image quality is degraded. This is because the eye follows the moving image, and the temporal integration region of the eye changes spatially. That is, if the line of sight moves at a speed of moving a plurality of pixels within one field display period, the addition of subfields is performed not over a single pixel but over a plurality of pixels, and a normal image cannot be obtained. Deteriorates.

FIG. 36 shows a case where the above problem is extreme, and FIG.
FIG. 9 is a diagram illustrating the gradation display method shown in FIG. 30 as an example. Pixel A and pixel B are arranged adjacently,
In the gradation display method shown in FIGS. 29 and 30, respectively, 127 gradations and 128 gradations are displayed. That is, for pixel A, 1sf to 7sf are on and 8sf is off, and for pixel B, 1sf to 7sf are off and 8sf
Only on. In FIG. 36, the arrangement direction of the pixels is shown as a vertical direction, and the arrangement direction of the subfields is shown as a horizontal direction. That is, the vertical direction in FIG. 36 indicates the spatial movement of the viewpoint, and the horizontal direction indicates the temporal movement of the viewpoint. Here, assuming that the viewpoint does not move from the pixel A (arrow c), the integrated value of one field of the pixel A becomes 1 as shown.
There are 27 tones. However, when the viewpoint is moved from pixel A to pixel B at a speed of two pixels in one field (arrow a),
The integrated values of the pixel A and the pixel B are both regarded as 255 gradations. Further, when the viewpoint is moved from the pixel B to the pixel A at a speed of two pixels in one field (arrow b), the integrated values of the pixels A and B are both regarded as 0 gradation.

FIG. 32 is a computer simulation of an image seen when a moving ramp waveform is displayed by the conventional subfield method in order to quantitatively measure the actual amount of image quality degradation. This simulation method is based on the calculation of the temporal integration amount of the eye when moving to the left at a speed of 8 pixels during each field display period.

[0009] The ramp waveform is originally a straight oblique line. However, in the conventional method, when the line of sight changes from “127” to “128” or from “63” to “64”, that is, where a new bit is set in binary display, it is remarkable. Noise is seen. In an actual image, this results in a pseudo-contour-like image quality deterioration.

As described above, in the conventional gradation display by the subfield method, when a screen is observed following the movement of an image, there is a considerable luminance difference between pixels having almost no original luminance difference. There is a problem that unnaturalness may be perceived.

When the above problem is to be solved by the conventional subfield method, the division of the subfield is subdivided to minimize the time length of each subfield (the gradation display shown in FIGS. 29 and 30). According to the law, it is conceivable to take measures to approach "1t"). However, since an increase in the number of subfields directly leads to an increase in memory capacity and an increase in power consumption and the like, subdivision of subfields is performed in a dark cloud. This leads to a large increase in cost. Therefore, it has been desired to realize a gradation display method capable of preventing a deterioration in the image quality of a moving image while suppressing an increase in cost by suppressing an increase in the number of subfield divisions as much as possible.

According to the present invention, in consideration of the above-mentioned problems of the conventional gradation display method, it is possible to prevent the image quality of a moving image from deteriorating when the subfield method is used, while suppressing an increase in cost. It is an object of the present invention to provide a gradation display method.

[0013]

In order to solve the above-mentioned problems, a first invention (corresponding to the first invention) is provided.
Comprises a plurality of time division time zones corresponding to one predetermined color in one frame / field, and sets temporal segments corresponding to the respective time division time zones; Consists of one or more subfields,
In the gradation display method for displaying the gradation of the predetermined one color by appropriately specifying ON / OFF of each of the subfields of the predetermined one color, the ON subfield and the OFF subfield are displayed. The number of segments in which subfields are mixed is set to 0 or 1, and each of the remaining segments is configured to include only the ON subfield or only the OFF subfield. When performing the display switching, priority is given to performing the on / off switching of the subfield in the same segment, and when performing the display switching of one gradation difference, the subfield that is on before the display switching is compared with the subfield that is on. The number of the segments in which the off-fields are mixed is 0
Except for the case where the segment is composed of a plurality of the sub-fields, the segment composed of only the sub-field of ON is switched to be composed of only the sub-field of OFF. ,
Further, there is provided a gradation display method, wherein switching is not performed so that the segment constituted only by the off subfield is constituted solely by the on subfield.

According to a second aspect of the present invention (corresponding to the second aspect of the present invention), when display switching of continuous gradation is performed, the segment to be switched on / off of the subfield is replaced with the segment. According to the temporal arrangement of the segments,
A gradation display method according to the first aspect of the present invention, which is characterized in that the method is selected.

According to a third aspect of the present invention (corresponding to the third aspect of the present invention), each of the sub-fields includes one frame / one frame.
The luminance obtained when all the sub-fields corresponding to the predetermined one color in the field are turned on is divided by the number of gradations into one unit, and is obtained when only the sub-field is turned on. And a weight corresponding to the luminance of the predetermined one color, and all or some of the plurality of subfields for each segment are n + 1 (n is a predetermined natural number) of the subfields. hand,
Each one is the one unit of 2 ⁰ , 2 ¹ ,..., 2
a binary subfield with ⁿ times said weight,
In the case of performing continuous gray scale display switching, on / off switching of each of the binary subfields is performed by 2 ⁰ , 2 ¹ ,.
2 is a gradation display method according to the first or second aspect of the present invention, which is performed with priority in an order corresponding to 2 ⁿ .

According to a fourth aspect of the present invention (corresponding to the fourth aspect of the present invention), a part of the plurality of subfields for each segment is different from the binary subfield in the subfield. In a certain adjustment subfield, when performing display switching of continuous gradation, on / off switching between the binary subfields is performed prior to on / off switching of the adjustment subfield. This is the third gradation display method of the present invention.

According to a fifth aspect of the present invention (corresponding to the fifth aspect of the present invention), each of the segments has only one of the adjustment subfields, and the only one of the adjustment subfields is A gradation display method according to a fourth aspect of the present invention, wherein the weight is one time of the one unit.

According to a sixth aspect of the present invention (corresponding to the sixth aspect of the present invention), the time when the weight corresponds to the predetermined one color in the one frame / field is divided by the number of gradations. The gradation display method according to any one of the first to fifth aspects of the present invention, wherein the time is a time length in which the time is one unit.

According to a seventh aspect of the present invention (corresponding to the seventh aspect of the present invention), when there is the subfield having the time length shorter than the load time of the data of each subfield, for each segment, A sixth gradation display method according to the present invention, wherein the subfields having the time length shorter than twice the load time are not consecutively arranged in time.

An eighth invention (corresponding to the invention according to claim 8) is that, when there is the subfield having the time length shorter than the load time of the data of each subfield, for each of the segments, A floor according to the sixth or seventh aspect of the present invention, wherein the subfield having the time length shorter than twice the load time is arranged at the beginning of time and / or at the end of time. This is a key display method.

With the above configuration, while suppressing an increase in cost,
It is possible to prevent the occurrence of an abnormal image due to the addition of subfields due to the movement of the line of sight, and to improve the image quality of the moving image.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) First, the first embodiment of the present invention will be described.
An embodiment will be described with reference to the drawings. 1 to 8
FIG. 3 is a diagram for explaining a gradation display method according to the first embodiment of the present invention. The gradation display method in the present embodiment is an example in the case of displaying an image of 8 bits, that is, 256 gradations. FIG. 1 is a configuration diagram of a subfield, FIG. 2 is a table showing which segments are turned on with respect to gray scales, and FIGS. Is a table showing whether or not the subfield is lit. When a character indicating the time length of the subfield is written in a corresponding position of each subfield, the subfield is lit (ON). If nothing is entered, it indicates that the subfield is not lit (off). This embodiment relates to a gradation display method in a projection-type device similar to that shown in FIG.
The color filters divided by RGB are rotated by using the elements to sequentially display red, green, and blue fields to obtain a color display. In the present embodiment, R
Since the color filter having a uniform angle of GB is rotated six times in one field period, each color has six light-segment separated periods (corresponding to the “time division time zone” of the present invention).
1 to 8 show only the structure of the green subfield, the time of each segment from segment 1 to segment 6 is equal, and R and B are between each segment.
Are separated by one segment.

In FIG. 1, similarly to FIG. 29 described in the conventional example, the time length of each subfield is weighted corresponding to the luminance of one color when only the subfield is turned on. In the case of the configuration shown in FIG. 31, this weighting corresponds to the time during which the mirror of the DMD is on (lit) or the number of pulses to be lit within this time length. . In this embodiment, one field is displayed using 36 subfields,
The 8-bit “256” gradation is almost equally distributed to the six segments, and segments 1 to 6 are assigned “42t”, “43t”, “42t”, “43t”,
They are distributed so as to have a time length of “42t” and “43t”. Here, t indicates a basic time (corresponding to “one unit” of the present invention) obtained by dividing the time for displaying green in one field time by 256 gradations.

In the present embodiment, as shown in FIG. 2, display is performed using the subfields in segment 1 for gradations "0" to "42" (at that time, the subfields of other segments are used). Are all non-lighted (off), and further, gradation display is performed using the subfields in segment 2 for gradations "43" to "86" (in this case, segment 1 always lights all subfields (on). ), And all the sub-fields after the segment 3 are not lit), so that the display up to a certain gradation for each segment is completed in order, and then the display up to the next gradation in the next segment is performed. Display is performed by continuous time width modulation.

As shown in FIGS. 3 to 8, in each segment, the time length of “42t” (or “43t”) is set to “11t” (or “12t”), “16t”,
It is divided into six subfields having the time lengths of “8t”, “4t”, “2t”, and “1t”, and the change of the gradation assigned to the segment by the combination of ON / OFF of these subfields Is displayed. To explain using segment 1 as an example, among the gradations from “0” to “42”,
"16t", "8t", "4" from "0" to "31"
The five subfields having a time length of "t", "2t", and "1t" are displayed in a binary system. "32" to "4"
As for the gradation between "2", two subfields having a time length of "11t" and "16t" are always turned on, and the rest are set to "8".
t "," 4t "," 2t ", and four subfields having a time length of" 1t "are displayed in a binary system. Similarly, for the segments 2 to 6, the change in the gradation assigned to the segment is displayed according to the on / off combination of the subfields constituting each segment. The subfields having the time lengths of “11t” and “12t” are “adjustment subfields” of the present invention.
"16t", "8t", "4t", "2t"
The subfield having a time length of “1t” corresponds to the “binary subfield” of the present invention.

That is, every time the gradation increases by 42 (or 43), the number of subfields increases continuously from segment 1 to segment 6 so that the subfields within the segment are lit. In order to complete the display, the subfield is displayed so as to be substantially lit according to the binary system.

FIG. 9 is a computer simulation of an image seen when a moving ramp waveform is displayed by the gradation display method according to the present embodiment.
The simulation method is the same as the method described in the conventional example, and is a calculation of the temporal integration amount of the eye when the eye is moved to the left at a speed of 8 pixels during each field display period. The waveform of FIG. 9 is different from the waveform of FIG. 32 in that the gradation is “127” to “128” or “63” to “6”.
It can be seen that when the line of sight changes to the pixel of "4", that is, at the place where a new bit stands in the binary display, the noise is greatly reduced. As a result, the image quality deterioration of the pseudo contour shape in the moving image is greatly improved.

In the present embodiment, the green subfield has been described as an example. However, it goes without saying that image quality degradation in moving images can be greatly reduced in the same manner for red and green.

In this embodiment, the configuration of the subfield of each segment is "11t" (or "12t").
t ")," 16t "," 8t "," 4t "," 2t ",
Although 6 subfields having a time length of “1t” are used,
“8t”, “4t”, “2t”, and “1t” are the same, and the remaining “27t” (or “28t”) is “10t” and “17t”, or “13t” and “14t”. Even if it is divided into two subfields with appropriate weighting, almost the same effect is exhibited. However, a subfield in which a part of a change in gradation assigned to the segment cannot be expressed in one segment is excluded. Taking a segment having a time length of “42t” as in the present embodiment as an example, the binary subfield of the present invention may have a time length of “8t”, “4t”, “2t”, and “1t”. And the combination of the subfields corresponding to the adjustment subfield of the present invention is a combination of “22t” and “5t” such that the time length difference between the two subfields is larger than “16t”. Such a subfield configuration corresponds to the configuration excluded above.

In this embodiment, the color filter having an equal angle of RGB as shown in FIG. 33 is rotated six times in one field period. However, the present invention is not limited to this, and as shown in FIG. The same is true even if the color filter divided into six equal to RGBRGB is rotated three times in one field, and furthermore, the color filters divided into nine, RGB, RGB, and RGB are rotated twice in one field, and furthermore, RGB ... RGB. The same is true even if the color filter divided into 18 is rotated once in one field.

(Second Embodiment) Next, a second embodiment of the present invention will be described.
An embodiment will be described with reference to the drawings. 10 to 1
FIG. 3 is a diagram for explaining a gradation display method according to the second embodiment of the present invention. The gradation display method in the present embodiment is also an example in the case of displaying an image of 8 bits, that is, 256 gradations, similarly to the gradation display method in the first embodiment. FIG. 10 is a configuration diagram of a subfield,
FIG. 11 is a table showing which segments are turned on with respect to gradation, and FIGS. 12 and 13 are tables showing which subfields are turned on with respect to gradation in each segment. If a character indicating the length of time of the subfield is entered in the corresponding place of the subfield, it indicates that the subfield is lit (turned on), and nothing is entered. Indicates that the subfield is not lit (is off). In the present embodiment, as in FIG. 31 described in the conventional example, the color filters divided by RGB are rotated using one DMD element to sequentially display the red, green, and blue fields, and color display is performed. Is what you get.
In the present embodiment, RGBRGB and 6 as shown in FIG.
Since the divided color filters are rotated three times in one field period, each color filter has a separated light emission period of six segments (corresponding to the “time division time zone” of the present invention). As shown in FIG. 35, the color filter used in the gradation display method according to the present embodiment has a difference in angle between the green G1 portion and the green G2 portion. Further, FIGS. 10 to 13 show only the configuration diagrams of the green subfield, but the time of each segment from segment 1 to 6 has a time difference depending on the angle of the color filter.

In FIG. 10, similarly to FIG. 29 described in the conventional example, the time length of each subfield is weighted corresponding to the luminance of one color when only the subfield is turned on. In the case of the configuration shown in FIG. 31, this weighting corresponds to the time during which the mirror of the DMD is on (lit) or the number of pulses to be lit within this time length. . In the present embodiment, one field is displayed using 33 subfields, 8-bit "256" gradations are distributed in proportion to the time of six segments, and segments 1 to 6 are represented by "31t", respectively. "54t", "31
"t", "55t", "31t", and "54t". Here, t indicates a basic time (corresponding to “one unit” of the present invention) obtained by dividing the time for displaying green in one field time by 256 gradations.

In the present embodiment, as shown in FIG. 11, display is performed using the subfields in segment 1 for gradations "0" to "31" (in this case, the subfields of other segments are not displayed). All are not lit (off), and further, gradation display is performed using the subfields in segment 2 from "32" to "85" gradation (in this case, all subfields in segment 1 are always lit (on)) Then, all the subfields after the segment 3 are not lit), the display up to a certain gray level is sequentially completed for each segment, and the display up to the next gray level is performed in the next segment. The display is performed by the appropriate time width modulation.

As shown in FIG. 12, in segments 1, 3, and 5 having a short time length, the time length of "31t" is changed to "16t", "8t", "4t", "2t",
It is divided into five subfields having a time length of “1t”, and the combination of on / off of these subfields is divided into
By performing the process in accordance with the notation, the change in the gradation assigned to the segment is displayed. That is, the segments 1, 3, and 5 are composed of only subfields corresponding to the “binary subfield” of the present invention.

As shown in FIG. 13, in segments 2, 4, and 6 having a long time length, the time length of "54t" is changed to "23t", "16t", "8t", "4t", respectively.
It is divided into six subfields having time lengths of "t", "2t", and "1t", and a change in gradation assigned to the segment is displayed by a combination of ON / OFF of these subfields. To explain using segment 2 as an example, among the gradations from “32” to “85”, “32t” to “63” represent “16t”, “8t”, “4t”, “2”
t "and five subfields having a time length of" 1t "are displayed according to a binary system. As for the gradation between “63” and “85”, two sub-fields with weights of “23t” and “16t” are always turned on, and the remaining subfields are “8t”, “4t”,
Subfield 4 having a time length of "2t" or "1t"
Displayed in binary according to the binary notation. Similarly, with respect to the segments 4 and 6, the change in the gradation assigned to the segment is displayed according to the on / off combination of the subfields constituting each segment. In the segments 2, 4, and 6, the subfield having the time length of “23t” corresponds to the “adjustment subfield” of the present invention, and is “16t”, “8t”, “4t”, “2t”.
Subfields having a time length of "t" and "1t" correspond to the "binary subfield" of the present invention.

That is, each time the gradation increases by 31 (or 54), the number of subfields in the segment increases continuously in order from segment 1 to segment 6 so as to light up. In order to complete the display, the subfield is displayed so as to be substantially lit according to the binary system. Even in this case, the first
The same effect as that of the embodiment can be expected.

The relationship between the color filter and the segment configuration (subfield configuration) is not limited to the relationship between the color filter shown in FIG. 35 and the segment configuration (subfield configuration) shown in FIG. According to the division, segment division is performed, the number of segments in which ON subfields and OFF subfields are mixed is set to 0 or 1, and the remaining segments are set to ON subfields only or , Off subfields only, and when performing continuous grayscale display switching, priority is given to on / off switching of the subfields within the same segment, and one grayscale difference is displayed. When switching, the number of segments in which ON subfields and OFF subfields are mixed before the display is switched Except in the case of, a segment composed of only a plurality of subfields is switched so that a segment composed of only ON subfields is composed of only OFF subfields, and The segment configuration (sub-field configuration) may be such that a segment configured only with sub-fields is not switched so as to be configured only with ON sub-fields.

(Third Embodiment) Next, a third embodiment of the present invention will be described.
An embodiment will be described with reference to the drawings. 14 to 1
FIG. 7 is a diagram for explaining a gradation display method according to the third embodiment of the present invention. The gradation display method in the present embodiment is also similar to the gradation display method in the first embodiment.
This is an example in the case of displaying an image of 8 bits, that is, 256 gradations. FIG. 14 is a configuration diagram of a subfield.
5 is a table showing which segment is turned on for the gradation, and FIGS. 16 and 17 are tables showing which subfields are turned on for the gradation in each segment.
If the corresponding place of each subfield has a character indicating the length of time that subfield has,
This indicates that the subfield is lit (ON), and that nothing is indicated indicates that the subfield is not lit (OFF).
In the present embodiment, as in FIG.
By using one of the DMD elements, a color filter divided by RGB is rotated to sequentially display red, green, and blue fields to obtain a color display. In the present embodiment, the color filter having an equal angle of RGB is rotated eight times in one field period, so that the light emitting period in which eight segments of each color are separated (corresponding to the “time division time zone” of the present invention)
Having. Further, FIGS. 14 to 17 show only the configuration diagrams of the green subfields. The time of each of the segments 1 to 8 is equal, and the interval between the segments is R.
And B are each separated by one segment.

In FIG. 14, similarly to FIG. 29 described in the conventional example, the time length of each subfield is weighted corresponding to the luminance of one color when only the subfield is turned on. In the case of the configuration shown in FIG. 31, this weighting corresponds to the time during which the mirror of the DMD is on (lit) or the number of pulses to be lit within this time length. . In the present embodiment, one field is displayed using 47 subfields, and 8-bit “256” gray scales
The segment 8 is allocated to have a time length of "32t", and the segment 8 is allocated to have a time length of "31t". Here, t indicates a basic time (corresponding to “one unit” of the present invention) obtained by dividing the time for displaying green in one field time by 256 gradations.

In the present embodiment, as shown in FIG. 15, display is performed using the subfields in segment 1 from "0" to "32" gradation (in this case, the subfields in the other segments are not displayed). All are turned off (off), and further, display is performed using the subfields in the segment 2 from "33" to "64" gradation (in this case, in the segment 1, all the subfields are always turned on (on), (Sub-fields after segment 3 are all turned off.) Display of up to a certain gradation is sequentially completed for each segment, and then display of the next gradation is performed in the next segment. The point that the display is performed by the width modulation is the same as that of the first embodiment.

As shown in FIG. 16, within each segment except for segment 8, “3t” of the time length of “32t”
The time length of “1t” is “16t”, “8t”, “4t”, respectively.
t "," 2t ", and" 1t "are divided into five subfields, and the on / off combination of these subfields is performed according to a binary system, so that the gray scale assigned to the segment is assigned. The change of is displayed. Finally, by lighting a subfield having a time length of "1t", which is the minimum bit, it is possible to express luminance corresponding to a time length of "32t". As described above, from segment 1 to segment 7, "3
2) For each gray level, a change in the gray level assigned to the segment is displayed according to the on / off combination of the subfields constituting each segment. In each of the above segments, the subfield having the time length of “1t” to be turned on last corresponds to the “adjustment subfield” of the present invention, and the remaining “16t”, “8t”, “4t”, “4t” 2
Subfields having a time length of "t" and "1t" correspond to the "binary subfield" of the present invention.

However, as for the display from the last "225" to "255" gradation, the time length of "31t" is set to "16" in the segment 8 as shown in FIG.
t "," 8t "," 4t "," 2t ", and five subfields having a time length of" 1t "are displayed in binary notation. That is, the segment 8 includes only subfields corresponding to the “binary subfield” of the present invention.

That is, every time the gray level is increased by 32, the subfields in the segment are sequentially increased from the segment 1 to the segment 8 so that the subfields are lit.
Within each segment, the subfields are illuminated in a binary manner to complete within that segment.

In the present embodiment, when the gradation is continuously increased, the lighting of the subfield in the segment is performed by the subfield having the time length of "1t" to be turned on at the end of the segments 1 to 7. Since the operation is performed according to the binary system except for the lighting of, the configuration is simplified.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described.
An embodiment will be described with reference to the drawings. 18 to 2
FIG. 1 is a diagram for explaining a gradation display method according to a fourth embodiment of the present invention. The gradation display method in the present embodiment is also an example in the case of displaying an image of 8 bits, that is, 256 gradations, similarly to the gradation display method in the first embodiment. FIG. 18 is a configuration diagram of a subfield,
FIG. 19 is a table showing which segments are turned on with respect to gradation, and FIGS. 20 and 21 are tables showing which subfields are turned on with respect to gradation in each segment. If a character indicating the length of time of the subfield is entered in the corresponding place of the subfield, it indicates that the subfield is lit (turned on), and nothing is entered. Indicates that the subfield is not lit (is off). In the present embodiment, as in FIG. 31 described in the conventional example, the color filters divided by RGB are rotated using one DMD element to sequentially display the red, green, and blue fields, and color display is performed. Is what you get.
In the present embodiment, the color filter having an equal angle of RGB is rotated four times in one field period. Therefore, the light emission period in which four segments of each color are separated (the “time division time zone” of the present invention)
Corresponding to). Further, FIGS. 18 to 21 show only the configuration diagrams of the green subfields. The time of each segment from segment 1 to segment 4 is equal, and the intervals of one segment each of R and B are empty between the segments. ing.

In FIG. 18, similarly to FIG. 29 described in the conventional example, the time length of each subfield is weighted corresponding to the luminance of one color when only the subfield is turned on. In the case of the configuration shown in FIG. 31, this weighting corresponds to the time during which the mirror of the DMD is on (lit) or the number of pulses to be lit within this time length. . In the present embodiment, one field is displayed using 27 subfields, and 8-bit “256” gray scales
The segment 4 is allocated to have a time length of “64t”, and the segment 4 is allocated to have a time length of “63t”. Here, t indicates a basic time (corresponding to “one unit” of the present invention) obtained by dividing the time for displaying green in one field time by 256 gradations.

In the present embodiment, as shown in FIG. 19, display is performed using the subfields in segment 1 from "0" to "64" gradation (the subfields of other segments are All are turned off (off), and further, display is performed using the subfields in segment 2 from “65” to “128” gradation (in this case, segment 1
Completes the display up to a certain gradation for each segment, such as that all subfields are always lit (on) and all subfields after segment 3 are not lit.
Then, display up to the next gradation in the next segment,
It is similar to the first embodiment in that display is performed by continuous time width modulation.

As shown in FIG. 20, in each segment except for segment 4, “6t” of the time length of “64t”
The time length of “3t” is “32t”, “16t”,
By dividing into six subfields having time lengths of “8t”, “4t”, “2t”, and “1t”, and performing on / off combinations of these subfields according to a binary system, Displays the change of the gradation assigned to it. Finally, by lighting a subfield having a time length of "1t", which is the minimum bit, it is possible to express luminance corresponding to a time length of "64t". In this manner, for each “64” gradation from segment 1 to segment 3, the change in gradation assigned to the segment is displayed by the combination of ON / OFF of the subfields constituting each segment. In each of the above segments, the subfield having the time length of “1t” to be turned on last corresponds to the “adjustment subfield” of the present invention, and the remaining “32t” and “16t”
Subfields having time lengths of “t”, “8t”, “4t”, “2t”, and “1t” correspond to the “binary subfield” of the present invention.

However, for the display from the last "193" to "255" gradation, as shown in FIG. 21, the time length of "63t" is set to "32" in the segment 4.
t "," 16t "," 8t "," 4t "," 2t ",
The five subfields having a time length of "1t" are displayed in a binary system. That is, the segment 4 includes only subfields corresponding to the “binary subfield” of the present invention.

That is, every time the gradation increases by 64, the number of the subfields in the segment increases continuously in order from segment 1 to segment 4 so that the subfields are turned on.
Within each segment, the subfields are illuminated in a binary manner to complete within that segment.

Also in this embodiment, as in the third embodiment, when the gradation is continuously increased, the lighting of the subfield in the segment is turned on at the end of the segments 1 to 3. Except for the lighting of the subfield having the time length of "1t", the operation is performed according to the binary system, so that the configuration is simplified.

(Fifth Embodiment) Next, a fifth embodiment of the present invention will be described.
An embodiment will be described with reference to the drawings. FIG. 22 is a diagram for explaining a gradation display method according to the fifth embodiment of the present invention. In the present embodiment, components that are not particularly described are the same as those in the first embodiment. FIG.
Is a table showing which segments are turned on for the gradation. In the present embodiment, the subfield configuration of each segment is the same as that of FIG. 1 described in the first embodiment. However, in this embodiment, the range from "0" to "42" The display is performed using the subfield (all the subfields of the other segments are not lit at that time), and further, the gradation display is performed using the subfield in the segment 5 from the "43" to "86" gradations ( At that time, in segment 6, all subfields are always lit,
The time axis of the continuity of the gradation between segments is exactly opposite to that of the first embodiment, for example, all the subfields of the segments 1 to 4 are not lit.

As described above, even if the time axis of the continuity of the gradation between the segments is directly opposite, the effect of suppressing the false contour of the moving image can be obtained equally. This can be applied not only to the first embodiment but also to the second to fourth embodiments.

(Sixth Embodiment) Next, a sixth embodiment of the present invention will be described.
An embodiment will be described with reference to the drawings. FIG. 23 is a diagram for explaining a gradation display method according to the sixth embodiment of the present invention. In the present embodiment, components that are not particularly described are the same as those in the first embodiment. FIG.
Is a table showing which segments are turned on for the gradation. In this embodiment, the subfield structure of each segment is the same as that of FIG. 1 described in the first embodiment, but in this embodiment, the subfields in segment 1 are from "0" to "42". Display using fields (all sub-fields of other segments are not lit)
Further, from the "43" to "86" gradations, gradation display is performed using the subfields in the segment 3 (in this case, all the subfields of the segment 1 are constantly lit, and the subfields of the segments other than the segments 1 and 3 are displayed). For example, the display is completed up to a certain gray level for each segment (for example, all the fields are not lit), but the continuity of segment on / off switching between segments is broken. That is, as shown in FIG.
(Or 43) As the number of sub-fields increases, the number of sub-fields increases continuously from segment 1 to segment 6 in any order so that sub-fields in the segment are lit. It is displayed so that it lights up according to the progressive system. If the number of segments in which on subfields and off subfields are mixed before display switching is 0, a segment consisting of a plurality of subfields consists of only on subfields. Switching the segment made up of only the off subfields, and making the segment made up of only the off subfields only the on subfield. Good. For example, FIG.
As shown in FIG. 3, when the display is switched from the “170” gradation to the “171” gradation, the segment 2 that was “all off” is turned “all on”, and the segment 6 that was “all on” is “All off” may be set. In other words, the order of segment on / off switching may be in any order regardless of the present embodiment.

As described above, even if the continuity of the on / off switching of the segments between the segments is broken, the effect of suppressing the pseudo contour of the moving image can be obtained equally. This can be applied not only to the first embodiment but also to the second to fifth embodiments. However, as in the segment selection procedure of the gradation display method in the first to fifth embodiments (as shown in FIGS. 2, 11, 15, 19, and 22), turning on the segments between the segments is performed. The continuity of the on / off switching has the effect of suppressing blurring of the moving image.

(Seventh Embodiment) Next, a seventh embodiment of the present invention will be described.
An embodiment will be described with reference to the drawings. 24 to 2
FIG. 7 is a diagram for explaining a gradation display method according to a seventh embodiment of the present invention. In the present embodiment, components that are not particularly described are the same as those in the first embodiment. FIG. 24 is a configuration diagram of a subfield, FIG. 25 is a table showing which segments are lit for gradations, and FIGS. 26 and 27 are which subfields are lit for gradations in each segment. This is a table showing whether the subfield is lit (on) when a character indicating the time length of the subfield is entered in the corresponding place of each subfield. If nothing is entered, it indicates that the subfield is not lit (off). In this embodiment, the number of segments and the subfield configuration are the same as those of the first embodiment, but the temporal arrangement of the subfields in the segment is different.

In this embodiment, one field is displayed using 36 subfields, and 8-bit "256" gradations are almost equally distributed to six segments, and "0" to "42" as shown in FIG. Display is performed using the subfields in segment 1 up to the "gray scale" (all the subfields in the other segments are turned off (off) at that time). (In this case, all the subfields of the segment 1 are always lit (ON), and all the subfields of the segment 3 and thereafter are not lit). Is the same as the first embodiment in that the display up to the next is completed, the display up to the next gradation is performed in the next segment, and the display is performed by continuous time width modulation.

In each segment, the time length of "42t" (or "43t") is set to "11t" (or "12t"), "16t", "8t", "4t", "2t", respectively.
The first embodiment also divides into six subfields having a time length of "t" and "1t" and displays a change in gradation assigned to the segment by a combination of ON / OFF of these subfields. This is the same as the embodiment.

However, in this embodiment, the temporal arrangement of the subfields in one segment is "1t"-"2t"-"4" in order from the subfield having the shorter time length.
t "-" 8t "-" 16t "-" 11t ". As described above, even if the temporal arrangement in the segment is not specified, the effect of suppressing the pseudo contour of the moving image can be obtained. However, as in the first embodiment of the present invention, “2t” is used.
-"16t"-"4t"-"8t"-"11t"-"1"
"2" which is a subfield having a short time length, such as "t".
The subfields having a time length of “t” and “1t” are arranged at the beginning and end of the segment, and the subfield having a time length of “4t” which is a short time length is replaced with another subfield having a time length of another short time length. "2t" which is a subfield,
By arranging the subfield so as not to be continuous with the subfield having the time length of “1t”, the problem described below can be avoided.

This problem is described in the literature (“10.4: Phased Reset”).
Timing for Improved Digital Micromirror Device (DM
D) Brightness ”SID 98 DIGEST pp.125-128) is described as a problem related to loading / resetting of write data of the DMD element. That is, as long as the load time is sufficiently shorter than 1t, the data of the next subfield can be loaded while the previous subfield is displayed, regardless of the temporal arrangement of the subfields. However, for example, when a subfield having a time length shorter than the load time comes, a problem arises that the time for loading the data of the next subfield is not sufficiently given. To solve this problem, subfields having a short time length may be arranged at the beginning and end of the segment. Because, at the beginning of the segment, a forced non-lighting time by a color change called a spoke time is provided immediately before the beginning of the segment, data loading / loading of the first subfield of the segment is performed during this time.
Reset becomes possible. Also, since the spoke time comes immediately after the end of the segment, it is not necessary to load the data of the next subfield.

FIG. 28 shows data loading / resetting when the reset group uses a four-phase reset. From this, it can be seen that in the first embodiment, even if there is a subfield having a time length shorter than the data load time, data can be sufficiently loaded / reset.

In the above description, “4t”, “2t”
The subfields having the time lengths of "2t" and "1t" are not arranged consecutively in time, and the subfields having the time lengths of "2t" and "1t" are temporally arranged at both ends of each segment. However, in general, if such measures are taken for a subfield having a time length shorter than twice the load time of the data of the subfield, the above-described problem can be avoided.

In the first to seventh embodiments, 256 gradations for red, green and blue have been described as an example. However, the present invention is not limited to this, and other colors and other gradations may be used. Also, the gradation display method of the present invention can be applied. Further, each subfield of the present invention has a unit of time obtained by dividing a time corresponding to a predetermined color in one frame by the number of gradations, and the predetermined one obtained when only the subfield is turned on. Although it has been described as having a time length corresponding to the luminance of one color, the present invention is not limited to this. What is necessary is just a thing which can obtain. In short, a time zone corresponding to one predetermined color in one frame / field is composed of a plurality of time division time zones, and a temporal segment corresponding to each time division time zone is set. Is composed of one or more subfields, and the gradation of the predetermined one color is displayed by appropriately specifying on / off of each of the subfields of the predetermined one color. , The number of the segments in which the ON sub-fields and the OFF sub-fields are mixed is set to 0 or 1, and each of the remaining segments is the ON sub-field only, or the OFF sub-field only. In the case where the display switching of the continuous gradation is performed, priority is given to performing the switching by turning on / off the subfield in the same segment. When the display switching of one gradation difference is performed, a plurality of the sub-fields except for the case where the number of the segments in which the on sub-fields and the off sub-fields are mixed before the display switching is 0. For the segment composed of the above, the segment composed of only the subfield of ON is switched to be composed only of the subfield of OFF, and composed only of the subfield of OFF. The gradation display method of the present invention can be applied by adopting a structure in which the segment is not switched so as to be constituted only by the ON subfield.

[0065]

As is apparent from the above description, the present invention provides a gradation display method capable of preventing the deterioration of the image quality of a moving image when the subfield method is used, while suppressing an increase in cost. be able to.

That is, according to the gradation display method of the present invention, it is possible to prevent the occurrence of an abnormal image due to the addition of an incorrect subfield due to the movement of the line of sight, and to improve the image quality of a moving image.

Further, in the display using the DMD, the restriction on the load time of the data is relaxed, and the temporal arrangement of the subfields which can be easily implemented becomes possible.

[Brief description of the drawings]

FIG. 1 is a subfield configuration diagram of a gradation display method according to a first embodiment of the present invention.

FIG. 2 is a segment selection table of a gradation display method according to the first embodiment of the present invention.

FIG. 3 is a subfield selection table for gradations 0 to 42 in the gradation display method according to the first embodiment of the present invention.

FIG. 4 is a subfield selection table for 43 to 85 gradations in the gradation display method according to the first embodiment of the present invention.

FIG. 5 is a subfield selection table for 86 to 127 gradations in the gradation display method according to the first embodiment of the present invention.

FIG. 6 is a subfield selection table for 128 to 170 gradations in the gradation display method according to the first embodiment of the present invention.

FIG. 7 is a subfield selection table for 171 to 212 gradations in the gradation display method according to the first embodiment of the present invention.

FIG. 8 is a subfield selection table for 213 to 255 gradations in the gradation display method according to the first embodiment of the present invention.

FIG. 9 is a diagram illustrating a simulation result of an image seen when a ramp waveform is moved by the gradation display method according to the first embodiment of the present invention.

FIG. 10 is a diagram illustrating a subfield configuration of a gradation display method according to a second embodiment of the present invention.

FIG. 11 is a segment selection table of a gradation display method according to the second embodiment of the present invention.

FIG. 12 is a subfield selection table for segments 1, 3, and 5 in the gradation display method according to the second embodiment of the present invention.

FIG. 13 is a subfield selection table in segments 2, 4, and 6 of the gradation display method according to the second embodiment of the present invention.

FIG. 14 is a diagram illustrating a subfield configuration of a gradation display method according to a third embodiment of the present invention.

FIG. 15 is a segment selection table of a gradation display method according to the third embodiment of the present invention.

FIG. 16 is a subfield selection table in segments 1 to 7 of the gradation display method according to the third embodiment of the present invention.

FIG. 17 is a subfield selection table in a segment 8 of the gradation display method according to the third embodiment of the present invention.

FIG. 18 is a diagram illustrating a subfield configuration of a gradation display method according to a fourth embodiment of the present invention.

FIG. 19 is a segment selection table of a gradation display method according to the fourth embodiment of the present invention.

FIG. 20 is a subfield selection table in segments 1 to 3 of the gradation display method according to the fourth embodiment of the present invention.

FIG. 21 is a subfield selection table in a segment 4 of the gradation display method according to the fourth embodiment of the present invention.

FIG. 22 is a segment selection table of a gradation display method according to the fifth embodiment of the present invention.

FIG. 23 is a segment selection table of a gradation display method according to the sixth embodiment of the present invention.

FIG. 24 is a diagram illustrating a subfield configuration of a gradation display method according to a seventh embodiment of the present invention.

FIG. 25 is a segment selection table of a gradation display method according to a seventh embodiment of the present invention.

FIG. 26 is a subfield selection table for segments 1, 3, and 5 in the gradation display method according to the seventh embodiment of the present invention.

FIG. 27 is a subfield selection table for segments 2, 4, and 6 in the gradation display method according to the seventh embodiment of the present invention.

FIG. 28 is a diagram illustrating a data load / reset operation according to the first embodiment of the gradation display method of the present invention.

FIG. 29 is a diagram showing a subfield configuration in a conventional gradation display method.

FIG. 30 is a subfield selection table in a conventional gradation display method.

FIG. 31 is a configuration diagram of a projection display device using a DMD.

FIG. 32 is a diagram showing a simulation result of an image seen when a ramp waveform is moved by a conventional gradation display method.

FIG. 33 is a schematic diagram of a color filter used for a gradation display method according to the first embodiment of the present invention.

FIG. 34 is a schematic diagram of a modification of the color filter used in the gradation display method according to the first embodiment of the present invention.

FIG. 35 is a schematic diagram of a color filter used in a gradation display method according to the second embodiment of the present invention.

FIG. 36 is a diagram showing movement of a viewpoint between pixels displaying a gray scale by a conventional gray scale display method.

[Explanation of symbols]

 Reference Signs List 11 DMD element 12 Color filter 13 Lamp 14 Projection lens

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Juichi Hitomi 1006 Odakadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Adam Kunsman USA Fairview Winford Court Texas Texas 1171

Claims (8)

[Claims] 1. A predetermined one within one frame / field
A time zone corresponding to one color is constituted by a plurality of time division time zones, a temporal segment corresponding to each time division time zone is set, and each segment is constituted by one or more subfields, In a gradation display method for displaying a gradation of one predetermined color by appropriately specifying ON / OFF of each of the subfields of the predetermined one color, the subfield of ON and the subfield of OFF are displayed. The number of the segments in which the fields and the fields are mixed is 0 or 1,
When each of the remaining segments is configured to include only the subfield that is ON or only the subfield that is OFF, and when performing continuous grayscale display switching, the subfield within the same segment is used. When the display is switched by one gradation difference, the number of the segments in which the on subfield and the off subfield are mixed before the display is switched becomes zero. Unless you have
For the segment composed of a plurality of the sub-fields, switching the segment composed only of the sub-field of ON to be composed only of the sub-field of OFF, and the sub-field of OFF A method for displaying gray scales, wherein switching is not performed so that a segment constituted only by sub-fields is constituted only by sub-fields which are turned on. 2. The method according to claim 1, wherein when performing display switching of continuous gradation, the segment to be switched on / off of the subfield is selected according to a temporal arrangement of the segment. Item 2. The gradation display method according to Item 1. 3. Each of the sub-fields is obtained by dividing a luminance obtained when all the sub-fields corresponding to the predetermined one color in the one frame / field are turned on by a gradation number. One unit, having a weight corresponding to the luminance of the predetermined one color obtained when only the subfield is turned on, All or a part of the plurality of subfields for each segment, n + 1 (n is a predetermined natural number) of the subfields, each one of which is the one unit of 2
⁰ , 2 ¹ ,..., 2 ⁿ times the binary subfield having the weight, and when performing the display switching of the continuous gradation, the on / off switching of each of the binary sub fields is performed by: 2 ⁰ , 2 ¹ , ...,
3. The gradation display method according to claim 1, wherein priority is given to the order corresponding to 2 ⁿ . 4. A case where a part of the plurality of subfields for each segment is an adjustment subfield which is another subfield different from the binary subfield, and a display of continuous gradation is switched. 4. The gradation display method according to claim 3, wherein on / off switching between the binary subfields is performed prior to on / off switching of the adjustment subfield. 5. Each of the segments has only one of the adjustment subfields, and the only one of the adjustment subfields is one of the one adjustment subfields.
The gradation display method according to claim 4, wherein the weight is twice as large. 6. The weight according to claim 1, wherein the weight is a time length in which one unit is a time obtained by dividing a time corresponding to the predetermined one color in the one frame / field by the number of gradations. Item 6. The gradation display method according to any one of Items 3 to 5. 7. When there is the subfield having the time length shorter than the data load time of each subfield, the subfield having the time length shorter than twice the load time is provided for each segment. 7. The gradation display method according to claim 6, wherein the pixels are not arranged continuously in time. 8. When there is the subfield having the time length shorter than the load time of the data of each of the subfields, the subfield having the time length shorter than twice the load time is provided for each segment. The gradation display method according to claim 6, wherein the gradation display method is arranged at a temporally first position and / or a temporally last position.