U.S. patent application number 11/506835 was filed with the patent office on 2006-12-14 for liquid crystal display device.
This patent application is currently assigned to Hitachi Displays, Ltd.. Invention is credited to Hiroshi Kurihara.
Application Number | 20060279522 11/506835 |
Document ID | / |
Family ID | 32757095 |
Filed Date | 2006-12-14 |
United States Patent
Application |
20060279522 |
Kind Code |
A1 |
Kurihara; Hiroshi |
December 14, 2006 |
Liquid crystal display device
Abstract
A liquid crystal display device of reduced power consumption has
a liquid crystal display panel and at least a backlight unit
disposed in opposition to a liquid crystal display part of the
liquid crystal display panel. The surface of the backlight unit
that is opposed to the liquid crystal display panel is divided into
a plurality of subunits capable of being individually adjusted in
brightness, and the liquid crystal display part is divided into
pixel blocks which are surface portions opposed to the respective
subunits. The liquid crystal display device includes a first unit
for calculating the highest brightness from display data inputted
to individual pixels in each of the pixel blocks, and a second unit
for adjusting, according to the magnitude of the highest brightness
calculated by the first means, the brightness of each of the
opposed subunits.
Inventors: |
Kurihara; Hiroshi; (Mobara,
JP) |
Correspondence
Address: |
REED SMITH LLP
3110 FAIRVIEW PARK DRIVE, SUITE 1400
FALLS CHURCH
VA
22042
US
|
Assignee: |
Hitachi Displays, Ltd.
|
Family ID: |
32757095 |
Appl. No.: |
11/506835 |
Filed: |
August 21, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10730007 |
Dec 9, 2003 |
7113164 |
|
|
11506835 |
Aug 21, 2006 |
|
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Current U.S.
Class: |
345/102 |
Current CPC
Class: |
G09G 3/3426 20130101;
G09G 3/3413 20130101; G09G 2360/16 20130101; G09G 3/3611 20130101;
G02F 1/133601 20210101 |
Class at
Publication: |
345/102 |
International
Class: |
G09G 3/36 20060101
G09G003/36 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 9, 2002 |
JP |
2002-356890 |
Claims
1. A liquid crystal display device comprising a liquid crystal
display panel and a backlight unit, wherein said liquid crystal
display panel having a display area, said backlight unit disposed
in opposition to said display area, and being divided into a
plurality of subunits capable of being individually adjusted in
brightness, said display area being divided into pixel blacks
opposed to said respective subunits, said liquid crystal display
device adjusts a brightness of at least one of said subunits
according to the display data inputted to corresponding pixel
block.
2. A liquid crystal display device according to claim 1, wherein
said backlight unit has a plurality of light-emitting elements.
3. A liquid crystal display device according to claim 2, wherein
said light-emitting elements include light-emitting diodes of three
kinds which respectively emit red, blue and green lights.
4. A liquid crystal display device according to, claim 3, further
comprising an optical sheet provided between said backlight unit
and said liquid crystal display panel.
5. A liquid crystal display device according to claim 1, wherein
said backlight unit is divided into a plurality of subunits
arranged in one direction and in another direction intersecting
said one direction.
6. A liquid crystal display device according to claim 1, wherein
said backlight unit is divided into a plurality of subunits
arranged in one direction.
7. A liquid crystal display device comprising a liquid crystal
display panel and a backlight unit, wherein said liquid crystal
display panel having a display area, said backlight unit disposed
in opposition to said display area, and being divided into a
plurality of subunits capable of being individually adjusted in
brightness, said display area being divided into pixel blocks
opposed to said respective subunits, said liquid crystal display
device calculates display data indicative of a highest brightness
from display data inputted to individual pixels in each of the
pixel blocks and increases a gray scale level of said display data
inputted to each of said pixels of each of said pixel blocks
according to said highest brightness of the corresponding one of
said pixel blocks and decreases a brightness of the corresponding
one of said subunits opposed to said respective pixel blocks
according to said highest brightness of each of said pixel
blocks.
8. A liquid crystal display device according to claim 7, wherein
said magnitude of increase of the gray scale level of said display
data is adjusted between white display and black display according
to the brightness value of the highest brightness.
9. A liquid crystal display device according to claim 7, wherein
said backlight unit has a plurality of light-emitting elements
arranged on a surface opposed to said liquid crystal display
panel.
10. A liquid crystal display device according to claim 7, wherein
said backlight unit has a plurality of light-emitting diodes
arranged on a surface opposed to said liquid crystal display panel
and said light-emitting diodes include light-emitting diodes of
three kinds which respectively emit red, blue and green lights.
11. A liquid crystal display device according to claim 10, further
comprising an optical sheet being provided between said backlight
unit and said liquid crystal display panel.
12. A liquid crystal display device according to claim 7, wherein
said backlight unit is divided into a plurality of subunits
arranged in one direction and in another direction intersecting
said one direction.
13. A liquid crystal display device according to claim 7, wherein
said backlight unit is divided into a plurality of subunits
arranged in one direction.
14. A liquid crystal display device comprising a liquid crystal
display panel and a backlight unit, wherein said liquid crystal
display panel having a display area, said backlight unit being
divided into a plurality of subunits capable of being individually
adjusted in brightness, said display area being divided into pixel
blocks opposed to said respective subunits, said liquid crystal
display device extracts an arbitrary number of display data from at
least one half of display data of higher brightness among all
display data inputted to individual pixels of each of said pixel
blocks, and calculates a brightness of each of said pixel blocks
from a total brightness or an average brightness according to said
extracted display data and adjusts a brightness of a corresponding
one of the subunits opposed to the respective pixel blocks
according to the magnitude of the brightness of each of said pixel
blocks.
15. A liquid crystal display device according to claim 14, wherein
said liquid crystal display device calculates said brightness
according to gray scale levels of said extracted display data.
16. A liquid crystal display device according to claim 14, wherein
said liquid crystal display device extracts one or more display
data.
17. A liquid crystal display device comprising a liquid crystal
display panel and a backlight unit, wherein, said liquid crystal
display panel having a display area, said backlight unit being
divided into a plurality of subunits capable of being individually
adjusted in brightness, said display area being divided into pixel
blocks opposed to said respective subunits, said liquid crystal
display device extracts an arbitrary number of display data from at
least one half of display data of higher brightness among all
display data inputted to individual pixels of each of the pixel
blocks and calculates a brightness of each of said pixel blocks
from a total brightness or an average brightness according to the
extracted display data and increases a gray scale level of each of
said display data inputted to said respective pixels of said pixel
block itself according to said brightness of each of said pixel
blocks and decreases the brightness of a corresponding one of said
subunits opposed to said respective pixel blocks according to the
brightness of each of said pixel blocks.
18. A liquid crystal display device according to claim 17, wherein
said liquid crystal display device calculates said brightness
according to gray scale levels of said extracted display data.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a Continuation application of U.S.
application Ser. No. 10/730,007 filed Dec. 9, 2003. Priority is
claimed based on U.S. application Ser. No. 10/730,007 filed Dec. 9,
2003, which claims the priority of Japanese Patent Application No.
2002-356890 filed Dec. 9, 2002, all of which is incorporated by
reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a liquid crystal display
device, and more particularly, to a liquid crystal display device
having a backlight unit on the back surface of its liquid crystal
display panel.
[0003] The liquid crystal display panel has a construction in which
a vessel is formed by transparent substrates disposed in opposition
to each other with a liquid crystal interposed therebetween and a
multiplicity of pixels are formed to be arranged in the spreading
direction of the liquid crystal.
[0004] Each of the pixels is provided with a pair of electrodes for
generating an electric field, and the optical transmissivity of the
liquid crystal is controlled by the electric field.
[0005] Accordingly, it is common practice that a backlight unit
serving as a light source is provided on the back surface of the
liquid crystal display panel.
[0006] Various kinds of backlight units are known, and there is a
recently known type of backlight unit, for reduction in the power
sumption in which light-emitting diodes (LEDs) of three kinds which
emit red, blue and green lights, respectively, are separately
disposed in close proximity to one another (Patent Document 1
(JP-A-7-191311) and Patent Document 2 (JP-A-10-221692)).
BRIEF SUMMARY OF THE INVENTION
[0007] However, when the liquid crystal display device is in use,
the backlight unit constructed in this manner is driven to emit
light consistently with high brightness, similarly to existing
types of backlight units. Accordingly, there has been a demand for
a further reduction in the power consumption of such a backlight
unit.
[0008] The invention has been made in view of this problem, and an
object of the invention is to provide a liquid crystal display
device capable of being reduced in power consumption to a further
extent.
[0009] Representative aspects of the invention disclosed herein
will be described below in brief.
[0010] The aspects of the invention will described below.
[0011] According to one aspect of the invention, a liquid crystal
display device has a liquid crystal display panel and a backlight
unit disposed in opposition to a liquid crystal display part of the
liquid crystal display panel, and the backlight unit is divided
into a plurality of subunits capable of being individually adjusted
in brightness and the liquid crystal display part is divided into
pixel blocks which are surface portions opposed to the respective
subunits. The liquid crystal display device includes first means
for calculating a highest brightness from display data inputted to
individual pixels in each of the pixel blocks, and second means for
adjusting, according to the magnitude of the highest brightness of
each of the pixel blocks calculated by the first means, a
brightness of a corresponding one of the subunits opposed to the
respective pixel blocks.
[0012] According to another aspect of the invention, a liquid
crystal display device has a liquid crystal display panel and a
backlight unit disposed in opposition to a liquid crystal display
part of the liquid crystal display panel, and the backlight unit is
divided into a plurality of subunits capable of being individually
adjusted in brightness and the liquid crystal display part is
divided into pixel blocks which are surface portions opposed to the
respective subunits. The liquid crystal display device includes:
first means for calculating display data indicative of a highest
brightness from display data inputted to individual pixels in each
of the pixel blocks; second means for increasing a gray scale level
of the display data inputted to each of the pixels of each of the
pixel blocks, according to the highest brightness of the
corresponding one of the pixel blocks calculated by the first
means; and third means for decreasing, according to the highest
brightness of each of the pixel blocks calculated by the first
means, a brightness of the corresponding one of the subunits
opposed to the respective pixel blocks.
[0013] According to another aspect of the invention, a liquid
crystal display device has a liquid crystal display panel and a
backlight unit disposed in opposition to a liquid crystal display
part of the liquid crystal display panel, and the backlight unit is
divided into a plurality of subunits capable of being individually
adjusted in brightness and the liquid crystal display part is
divided into pixel blocks which are surface portions opposed to the
respective subunits. The liquid crystal display device includes:
first means for extracting an arbitrary number of display data from
at least one half of display data of higher brightness among all
display data inputted to individual pixels of each of the pixel
blocks, and calculating a brightness of each of the pixel blocks
from a total brightness or an average brightness according to the
extracted display data; and second means for adjusting, according
to the magnitude of the brightness of each of the pixel blocks
calculated by the first means, a brightness of a corresponding one
of the subunits opposed to the respective pixel blocks.
[0014] The first means calculates the brightness according to, for
example, gray scale levels of the extracted display data. In
addition, the first means extracts, for example, one or more
display data. The number of display data to be extracted may also
be two or more.
[0015] According to another aspect of the invention, a liquid
crystal display device has a liquid crystal display panel and a
backlight unit disposed in opposition to a liquid crystal display
part of the liquid crystal display panel, and the backlight unit is
divided into a plurality of subunits capable of being individually
adjusted in brightness and the liquid crystal display part is
divided into pixel blocks which are surface portions opposed to the
respective subunits. The liquid crystal display device includes:
first means for extracting an arbitrary number of display data from
at least one half of display data of higher brightness among all
display data inputted to individual pixels of each of the pixel
blocks, and calculating a brightness of each of the pixel blocks
from a total brightness or an average brightness according to the
extracted display data; second means for increasing, according to
the brightness of each of the pixel blocks calculated by the first
means, a gray scale level of each of the display data inputted to
the respective pixels of the pixel block itself; and third means
for decreasing, according to the brightness of each of the pixel
blocks calculated by the first means, the brightness of a
corresponding one of the subunits opposed to the respective pixel
blocks.
[0016] The first means calculates the brightness according to, for
example, gray scale levels of the extracted display data. The first
means extracts, for example, one or more display data. The number
or display data to be extracted may also be two or more.
[0017] The invention is not limited to any of the above-described
construction, and can be modified in various ways without departing
from the technical idea of the invention.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0018] The invention will become more readily appreciated and
understood from the following detailed description of preferred
embodiments of the invention when taken in conjunction with the
accompanying drawings, in which:
[0019] FIG. 1 is a schematic view showing the construction of a
first embodiment of a liquid crystal display device according to
the invention;
[0020] FIG. 2 is a schematic, exploded perspective view showing the
first embodiment of the liquid crystal display device according to
the invention;
[0021] FIG. 3 is an explanatory view showing the operation of the
liquid crystal display device according to the invention;
[0022] FIG. 4 is a graph showing the relationship between input
data and display brightness in the first embodiment of the liquid
crystal display device according to the invention;
[0023] FIG. 5 is a schematic view showing the construction of a
second embodiment of the liquid crystal display device according to
the invention; and
[0024] FIG. 6 is a graph showing the relationship between input
data and display brightness in the second embodiment of the liquid
crystal display device according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0025] Preferred embodiments of a liquid crystal display device
according to the invention will be described below with reference
to the accompanying drawings.
[0026] Embodiment 1.
[0027] FIG. 2 is a schematic view showing the construction of one
embodiment of a liquid crystal display device according to the
invention. In FIG. 2, a liquid crystal display panel PNL, color
mixing means MCM and a backlight unit BLU are arranged in that
order from an observer side.
[0028] The liquid crystal display panel PNL has a construction in
which a vessel is formed by, for example, transparent substrates
disposed in opposition to each other with a liquid crystal
interposed therebetween and a multiplicity of pixels are formed to
be arranged in the spreading direction of the liquid crystal. In
each of the pixels, the liquid crystal is varied in optical
transmissivity by an electric field generated by a pair of
electrodes provided in itself and light from the backlight unit BLU
is allowed to be transmitted through the liquid crystal so as to
reach the eyes of an observer.
[0029] The liquid crystal display panel PNL also has a liquid
crystal drive circuit including, for example, a scanning signal
drive circuit and a video signal drive circuit which are mounted on
the periphery of its liquid crystal display part. Display data
inputted to the liquid crystal display device from the outside
thereof is inputted to the liquid crystal drive circuit, and an
image is displayed on the liquid crystal display part by a scanning
signal and a video signal supplied from the liquid crystal drive
circuit.
[0030] It is to be noted that this liquid crystal display panel PNL
is, for example, of the type which provides color display and whose
pixels each have three mutually adjacent pixels containing red,
blue and green filters, respectively.
[0031] The backlight unit BLU has a construction in which a
multiplicity of light-emitting diodes LED are arranged in a matrix
form on a substrate of approximately the same size as the liquid
crystal display panel PNL on the side where the liquid crystal
display panel PNL is disposed.
[0032] These light-emitting diodes LED are arranged so that, for
example, light-emitting diodes of the same kind that emit light of
the same color are arrayed in the same column in the y direction of
the substrate, and are also arrayed to repeat the order of red (R),
green (G) and blue (B) along the same row in the x direction of the
substrate.
[0033] In this case, the respective light-emitting diodes LED need
not be disposed to correspond to the individual pixels of the
liquid crystal display panel PNL, and, for example, each individual
one of the light-emitting diodes LED may be disposed in opposition
to a plurality of adjacent ones of the pixels of the liquid crystal
display panel PNL.
[0034] The color mixing means MCM is made of, for example, an
optical sheet, and serves to mix lights of different colors emitted
from the backlight unit BLU and transmit white light to the liquid
crystal display panel PNL.
[0035] As shown in FIG. 1, the light-emitting diodes LED of the
backlight unit BLU are grouped into a plurality of subunits A, B, .
. . , each of which includes mutually adjacent ones of the
light-emitting diodes LED. Brightness to be provided by the
light-emitting diodes LED is adjusted for each of the subunits A,
B, . . . .
[0036] In this embodiment, the light-emitting diodes LED of the
backlight unit BLU is grouped into a plurality of subunits in both
of the x and y directions, but may also be grouped into a plurality
of subunits in only either one of the x and y directions. The
number of subunits into which the light-emitting diodes LED are to
be grouped may be arbitrary, but it goes without saying that it is
far more preferable to increase such number.
[0037] Display data inputted to the liquid crystal display panel
PNL is inputted to the liquid crystal drive circuit incorporated in
the liquid crystal display panel PNL and to display gray scale
analysis means SAM.
[0038] The display gray scale analysis means SAM is constructed to
perform the following operation. Namely, the liquid crystal display
part of the liquid crystal display panel PNL is divided into
portions which are respectively opposed to the corresponding ones
of the subunits A, B, . . . of the backlight unit BLU, that is to
say, portions each of which allows transmission of light from the
corresponding one of the subunits A, B, . . . , and the display
gray scale analysis means SAM calculates the brightness of a video
signal representative of the highest brightness among video signals
(for example, gray scale levels) supplied to the respective pixels
of each of the thus-divided pixel blocks A, B, . . . of the liquid
crystal display panel PNL, on the basis of pixel information
inputted to each of the pixels of each individual one of the pixel
blocks A, B, . . . .
[0039] It is therefore to be understood that the division of the
liquid crystal display panel PNL merely signifies division into
domains on each of which to calculate the brightness of a pixel
having the highest brightness among a plurality of pixels, and
shall not be construed to divide the liquid crystal display panel
PNL physically nor electrically.
[0040] After the highest brightness has been calculated on each of
the pixel blocks A, B, . . . in this manner, signals corresponding
to the respective highest brightnesses are inputted to the
corresponding ones of subunit brightness adjustment means A(1), B
(2), which respectively adjust the brightnesses of the subunits A,
B, . . . of the backlight unit BLU that correspond to the
respective pixel blocks A, B, . . . . Each of the subunit
brightness adjustment means A(1), B (2), . . . is operative to
cause emissions from the light-emitting diodes LED of the
corresponding one of the subunits A, B, . . . according to the
highest brightness thereof on the basis of its input signal.
Namely, if the highest brightness in any one or ones of the pixel
blocks A, B, . . . is low, the brightness of the corresponding one
or ones of the subunits A, B, . . . is set low; whereas if the
highest brightness in any one or ones of the pixel blocks A, B, . .
. is high, the brightness of the corresponding one or ones of the
subunits A, B, . . . is set high.
[0041] Driving of each of the subunit brightness adjustment means
A(1), B (2), . . . is effected by a vertical synchronizing signal
Vsync supplied to the liquid crystal display device.
[0042] FIG. 3 is an explanatory view showing further details of the
operation of the liquid crystal display device. In the following
description, reference will be made to the case where the highest
brightness of, for example, the pixel block A corresponding to the
position of the subunit A is a gray scale level of, for example,
255 (white), while the highest brightness of, for example, the
pixel block B corresponding to the position of the subunit B is a
gray scale level of, for example, 50.
[0043] The display gray scale analysis means SAM analyzes input
data, and finds, for example, 10 as brightness information A as to
each pixel of the pixel block A corresponding to the position of
the subunit A and, for example, 2 as brightness information B as to
each pixel of the pixel block B corresponding to the position of
the subunit B. This operation means that the display gray scale
analysis means SAM employs a table in which, for example, gray
scale levels of 0 to 255 are divided into 10 levels, and, in the
case of a gray scale level of 255, finds brightness information
indicative of the maximum level of 10 from among the 10 levels,
and, in the case of a gray scale level of 50, finds brightness
information indicative of the second lowest level of 2 from among
the 10 levels.
[0044] Then, the brightness information A is inputted to the
subunit brightness adjustment means A(1), and the subunit
brightness adjustment means A(1) adjusts the value of an electric
current to flow into the light-emitting diodes LED of the subunit
A, on the basis of the brightness information A, and causes the
light-emitting diodes LED to emit light. In this case, the
light-emitting diodes LED emit light with brightness corresponding
to the brightness information of 10, that is to say, with high
brightness.
[0045] In addition, the brightness information B is inputted to the
subunit brightness adjustment means B(2), and the subunit
brightness adjustment means B(2) adjusts the value of an electric
current to flow into the light-emitting diodes LED of the subunit
B, on the basis of the brightness information B, and causes the
light-emitting diodes LED to emit light. In this case, the
light-emitting diodes LED emit light with brightness corresponding
to the brightness information of 2, that is to say, with
comparatively low brightness.
[0046] In the meantime, the input data is also inputted to the
video signal drive circuit and to the scanning signal drive
circuit, and is visually displayed on the liquid crystal display
panel PNL.
[0047] FIG. 4 shows the relationship between the input data and
display brightness (brightness recognized by an observer) in this
embodiment. In this case, with respect to the same input data (for
example, a gray scale level of 50), the pixel block A exhibits a
display brightness of, for example, 40, while the pixel block B
exhibits a display brightness of, for example, 30. In either case,
the display brightness is smaller than the display brightness of 50
obtainable from the highest brightness of the backlight unit BLU.
This is because each of the subunit brightness adjustment means
adjusts the brightness of the corresponding one of the subunits in
the backlight unit BLU, while the brightness of each pixel in the
corresponding one of the pixel blocks of the liquid crystal display
panel PNL is also adjusted on the basis of the input display
data.
[0048] However, even in this case, the backlight unit BLU adjusts
the brightnesses of its domains corresponding to the respective
divided domains of the liquid crystal display panel PNL according
to the magnitudes of the brightnesses of the respective divided
domains of the image displayed on the liquid crystal display panel
PNL, whereby low power consumption can be realized.
[0049] Embodiment 2.
[0050] FIG. 5 is a schematic view showing the construction of
another embodiment of the liquid crystal display device according
to the invention, and FIG. 5 is a view corresponding to FIG. 1.
[0051] The construction shown in FIG. 5 differs from that shown in
FIG. 1 in that a liquid-crystal-driving gray scale compensation
circuit SAC is newly added, and display data to be inputted to the
display gray scale analysis means SAM and the brightness
information A, B, . . . to be inputted to the respective subunit
brightness adjustment means A(1), B(2), . . . from the display gray
scale analysis means SAM are inputted to the liquid-crystal-driving
gray scale compensation circuit SAC.
[0052] The output from the liquid-crystal-driving gray scale
compensation circuit SAC is transmitted to the liquid crystal drive
circuit of the liquid crystal display panel PNL.
[0053] Namely, the liquid-crystal-driving gray scale compensation
circuit SAC increases the gray scale levels of video signals
supplied to the respective pixels of each of the pixel blocks A, B,
. . . corresponding to the display data, on the basis of the input
brightness information A, B, . . . .
[0054] In this case, it is appropriate that the magnitude of
increase of the gray scale levels of the video signals is made
smaller as the values of the brightness information (A, B, . . . )
supplied from the display gray scale analysis means SAM become
larger, while the magnitude of increase of the gray scale levels is
made larger as such values become smaller.
[0055] It goes without saying that the magnitude of increase of the
gray scale levels of the video signals is adjusted between white
display and black display according to the brightness value of the
above-described highest brightness.
[0056] According to this construction, the liquid-crystal-driving
gray scale compensation circuit SAC can solve the disadvantage that
the display brightness lowers as shown in FIG. 4 in the case of the
construction of the liquid crystal display device shown in FIG.
1.
[0057] FIG. 6 is a view showing the relationship between the input
data and the display brightness (brightness recognized by an
observer) in this embodiment. FIG. 6 is a graph corresponding to
FIG. 4.
[0058] Specifically, if the input data has a gray scale level of 50
similarly to that shown in FIG. 4, the brightness information of
video signals supplied to the pixel block A is increase to, for
example, a gray scale level of 60, while the brightness information
of video signals supplied to the pixel block B is increased to, for
example, a gray scale level of 100.
[0059] Accordingly, in either of the pixel blocks A and B, the
display brightness is recognized as a gray scale level of 50 by an
observer, so that light from the backlight unit BLU can be used to
the maximum.
[0060] As is apparent from the foregoing description, according to
the liquid crystal display device of the invention, it is possible
to realize a far lower power consumption.
[0061] In either of Embodiments 1 and 2, the highest brightness is
calculated from display data inputted to the respective pixels of
each of the pixel blocks and the magnitudes of the brightnesses of
the respective pixel blocks are determined, but it is, of course,
possible to use other methods as will be described below.
[0062] For example, display data inputted to the respective pixels
of each of the pixel blocks are sorted from the highest brightness
to the lowest brightness, and an arbitrary number of display data
are extracted from one half of the display data counted from the
display data of highest brightness, whereby the magnitude of
brightness of each of the pixel blocks can be determined from the
total brightness or the average brightness of the extracted display
data. The number of display data to be extracted may be arbitrary,
for example, one, two or three, but it is desirable to extract
about one to three display data having as high brightness as
possible.
[0063] Otherwise, display data inputted to the respective pixels of
each of the pixel blocks are sorted from the highest brightness to
the lowest brightness, and an arbitrary number of display data are
extracted from the one-thirds of the display data that are counted
from the display data of highest brightness, whereby the magnitude
of brightness of each of the pixel blocks can be determined from
the total brightness or the average brightness of the extracted
display data.
[0064] Otherwise, display data inputted to the respective pixels of
each of the pixel blocks are sorted from the highest brightness to
the lowest brightness, and an arbitrary number of display data are
extracted from any of the one-fourths, one-fifths, . . . of the
display data that are counted from the display data of highest
brightness, whereby the magnitude of brightness of each of the
pixel blocks can be determined from the total brightness or the
average brightness of the extracted display data. In the case of
these fine divisions as well, it is possible to calculate the
highest brightness from display data inputted to the respective
pixels of each of the pixel blocks and determine the magnitude of
brightness of each of the pixel blocks, as described previously in
Embodiments 1 and 2.
* * * * *