U.S. patent application number 16/919117 was filed with the patent office on 2022-01-06 for circuitry, local dimming control method and display apparatus.
The applicant listed for this patent is HIMAX TECHNOLOGIES LIMITED. Invention is credited to Chih-Ying LIN, Chia-Wei TSAI.
Application Number | 20220005421 16/919117 |
Document ID | / |
Family ID | |
Filed Date | 2022-01-06 |
United States Patent
Application |
20220005421 |
Kind Code |
A1 |
LIN; Chih-Ying ; et
al. |
January 6, 2022 |
CIRCUITRY, LOCAL DIMMING CONTROL METHOD AND DISPLAY APPARATUS
Abstract
A circuitry for controlling a backlight module, the circuitry
includes a local dimming control circuit and a backlight control
circuit. The local dimming control circuit is configured to
generate local dimming data based on image data and an arrangement
of a plurality of light emitting units of the backlight module, in
which the local dimming data includes a first local dimming data
corresponding to a first light emitting unit of the plurality of
light emitting units and a second local dimming data corresponding
to a second light emitting unit of the plurality of light emitting
units, and the number of bits of the first local dimming data is
different from the number of bits of the second local dimming data.
The backlight control circuit is configured to control the
backlight module to irradiate backlight based on the local dimming
data.
Inventors: |
LIN; Chih-Ying; (Tainan
City, TW) ; TSAI; Chia-Wei; (Tainan City,
TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HIMAX TECHNOLOGIES LIMITED |
Tainan City |
|
TW |
|
|
Appl. No.: |
16/919117 |
Filed: |
July 2, 2020 |
International
Class: |
G09G 3/34 20060101
G09G003/34; G09G 3/36 20060101 G09G003/36 |
Claims
1. A circuitry for controlling a backlight module, the circuitry
comprising: a local dimming control circuit configured to generate
local dimming data based on image data and an arrangement of a
plurality of light emitting units of the backlight module, wherein
the local dimming data includes a first local dimming data
corresponding to a first light emitting unit of the plurality of
light emitting units and a second local dimming data corresponding
to a second light emitting unit of the plurality of light emitting
units, and wherein the number of bits of the first local dimming
data is different from the number of bits of the second local
dimming data, the first local dimming data has most significant
bits and least significant bits, and the second local dimming data
only has least significant bits; and a backlight control circuit
configured to control the backlight module to irradiate backlight
based on the local dimming data, wherein the local dimming control
circuit is further configured to provide an indication signal for
indicating the backlight control circuit to combine the most
significant bits of the first local dimming data and the least
significant bits of the second local dimming data into a combined
second local dimming data for the second light emitting unit.
2. The circuitry of claim 1, wherein each of the first and second
local dimming data includes an indication bit, and wherein the
indication bits of the first and second local dimming data are of
opposite bit values.
3-5. (canceled)
6. The circuitry of claim 1, wherein the backlight control circuit
comprises a memory that stores the most significant bits of the
first local dimming data.
7. The circuitry of claim 1, wherein the local dimming data further
includes a third local dimming data corresponding to a third light
emitting unit of the plurality of light emitting units, and wherein
the number of bits of the third local dimming data is the same as
the number of bits of the second local dimming data and less than
the number of bits of the first local dimming data.
8. The circuitry of claim 7, wherein each of the first to third
local dimming data includes an indication bit; wherein the
indication bits of the first and second local dimming data are of
opposite bit values, and the indication bits of the second and
third local dimming data are of the same bit value.
9. (canceled)
10. The circuitry of claim 1, wherein the local dimming control
circuit is further configured to transmit an initial code data to
the backlight control circuit subsequent to the local dimming data
for refreshing an original initial code data stored in the
backlight control circuit.
11-19. (canceled)
20. A display apparatus comprising: a display panel configured to
display an image based on image data; a backlight module configured
to provide backlight for the display panel to display the image,
the backlight module having a plurality of light emitting units; a
local dimming control circuit configured to generate local dimming
data based on the image data and an arrangement of the plurality of
light emitting units; and a backlight control circuit configured to
control the backlight module to irradiate the backlight based on
the local dimming data; wherein the local dimming data includes a
first local dimming data corresponding to a first light emitting
unit of the plurality of light emitting units and a second local
dimming data corresponding to a second light emitting unit of the
plurality of light emitting units, and wherein the number of bits
of the first local dimming data is different from the number of
bits of the second local dimming data, the first local dimming data
has most significant bits and least significant bits, and the
second local dimming data only has least significant bits, wherein
the local dimming control circuit is further configured to provide
an indication signal for indicating the backlight control circuit
to combine the most significant bits of the first local dimming
data and the least significant bits of the second local dimming
data into a combined second local dimming data for the second light
emitting unit.
21. A circuitry for controlling a backlight module, the circuitry
comprising: a local dimming control circuit configured to generate
local dimming data based on image data and an arrangement of a
plurality of light emitting units of the backlight module, wherein
the local dimming data includes a first local dimming data
corresponding to a first light emitting unit of the plurality of
light emitting units and a second local dimming data corresponding
to a second light emitting unit of the plurality of light emitting
units, and wherein the number of bits of the first local dimming
data is different from the number of bits of the second local
dimming data, the first local dimming data has most significant
bits and least significant bits, and the second local dimming data
only has least significant bits; and a backlight control circuit
configured to control the backlight module to irradiate backlight
based on the local dimming data, wherein the local dimming control
circuit is further configured to provide an indication signal for
notifying the backlight control circuit of a number of the least
significant bits of each of the first and second local dimming
data.
Description
BACKGROUND
Field of the Invention
[0001] The invention relates to local dimming, and more
particularly to a circuitry and a local dimming control method for
a backlight module and a display apparatus with local dimming
functionality.
Description of Related Art
[0002] A conventional liquid crystal display (LCD) device normally
includes a backlight module for providing a backlight source in
order to display images. Furthermore, a local dimming technology
may be applied to the backlight module to increase the contrast of
the LCD device, in which the backlight brightness of specific parts
are determined according to the gray level distribution of an image
to be displayed. In some examples, for displaying a high gray level
portion of an image, the corresponding part of the backlight module
will output light with relatively high brightness; for displaying a
low gray level portion of an image, the corresponding part of the
backlight module will output light with relatively low brightness.
However, in order to deal with more and more specific parts of the
backlight module and higher screen display frequency (e.g.
90/120/240 Hertz), how to save the amount of local dimming data for
transmission is one of the important issues for the industries.
SUMMARY
[0003] One aspect of the invention directs to circuitry for
controlling a backlight module, the circuitry includes a local
dimming control circuit and a backlight control circuit. The local
dimming control circuit configured to generate local dimming data
based on image data and an arrangement of a plurality of light
emitting units of the backlight module, wherein the local dimming
data includes a first local dimming data corresponding to a first
light emitting unit of the plurality of light emitting units and a
second local dimming data corresponding to a second light emitting
unit of the plurality of light emitting units, and wherein the
number of bits of the first local dimming data is different from
the number of bits of the second local dimming data. The backlight
control circuit configured to control the backlight module to
irradiate backlight based on the local dimming data.
[0004] In accordance with one or more embodiments of the invention,
each of the first and second local dimming data includes an
indication bit, and the indication bits of the first and second
local dimming data are of opposite bit values.
[0005] In accordance with one or more embodiments of the invention,
the first local dimming data has most significant bits and least
significant bits, and the second local dimming data only has least
significant bits.
[0006] In accordance with one or more embodiments of the invention,
the local dimming control circuit is further configured to provide
a first indication signal for indicating the backlight control
circuit to combine the most significant bits of the first local
dimming data and the least significant bits of the second local
dimming data into a combined second local dimming for the second
light emitting unit.
[0007] In accordance with one or more embodiments of the invention,
the local dimming control circuit is further configured to provide
a second indication signal for notifying the backlight control
circuit of the number of least significant bits of each of the
first and second local dimming data.
[0008] In accordance with one or more embodiments of the invention,
the backlight control circuit comprises a memory that stores the
most significant bits of the first local dimming data.
[0009] In accordance with one or more embodiments of the invention,
the local dimming data further includes a third local dimming data
corresponding to a third light emitting unit of the light emitting
units, and the number of bits of the third local dimming data is
the same as the number of bits of the second local dimming data and
less than the number of bits of the first local dimming data.
[0010] In accordance with one or more embodiments of the invention,
each of the first to third local dimming data includes an
indication bit, the indication bits of the first and second local
dimming data are of opposite bit values, and the indication bits of
the second and third local dimming data are of the same bit
value.
[0011] In accordance with one or more embodiments of the invention,
the first local dimming data has most significant bits and least
significant bits, and each of the second and third local dimming
data only has least significant bits.
[0012] In accordance with one or more embodiments of the invention,
the local dimming control circuit is further configured to transmit
an initial code data to the backlight control circuit subsequent to
the local dimming data for refreshing an original initial code
stored in the backlight control circuit.
[0013] Another aspect of the invention is directed to a local
dimming control method for a backlight module. The local dimming
control method includes: generating local dimming data based on
image data and an arrangement of a plurality of light emitting
units of the backlight module; and transmitting the local dimming
data to a backlight control circuit that controls the backlight
module to irradiate backlight accordingly. The local dimming data
including a first local dimming data corresponding to a first light
emitting unit of the plurality of light emitting units and a second
local dimming data corresponding to a second light emitting unit of
the plurality of light emitting units. The number of bits of the
first local dimming data is different from the number of bits of
the second local dimming data.
[0014] A further aspect of the invention is directed to a display
apparatus which includes a display panel, a backlight module, a
local dimming control circuit and a backlight control circuit. The
display panel is configured to display an image based on image
data. The backlight module has light emitting units, and is
configured to provide backlight for the display panel to display
the image. The local dimming control circuit is configured to
generate local dimming data based on the image data and an
arrangement of the plurality of light emitting units. The backlight
control circuit is configured to control the backlight module to
irradiate the backlight based on the local dimming data. The local
dimming data includes a first local dimming data corresponding to a
first light emitting unit of the plurality of light emitting units
and a second local dimming data corresponding to a second light
emitting unit of the plurality of light emitting units, and the
number of bits of the first local dimming data is different from
the number of bits of the second local dimming data.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The foregoing aspects and many of the accompanying
advantages of this invention will become more readily appreciated
as the same becomes better understood by reference to the following
detailed description, when taken in conjunction with the
accompanying drawings.
[0016] FIG. 1 is a schematic diagram of a display apparatus in
accordance with one or more embodiments of the invention.
[0017] FIG. 2 exemplarily illustrates the backlight control circuit
and the backlight module in FIG. 1 in addition to a local dimming
control circuit in accordance with one or more embodiments of the
invention.
[0018] FIG. 3A exemplarily illustrates a scanning pattern of the
light emitting units of the backlight module in FIG. 2.
[0019] FIG. 3B exemplarily illustrates another scanning pattern of
the light emitting units of the backlight module in FIG. 2.
[0020] FIG. 4 is a timing diagram of the local dimming data signal
and the reference clock signal transmitted by the local dimming
control circuit in FIG. 2 in accordance with one or more exemplary
embodiments of the invention.
[0021] FIG. 5 a flowchart of a local dimming data transmission
method performed by the local dimming control circuit in FIG. 2 in
accordance with one or more embodiments of the invention.
[0022] FIG. 6 exemplarily illustrates the backlight control circuit
and the backlight module in FIG. 1 in addition to a local dimming
control circuit in accordance with another one or more embodiments
of the invention.
[0023] FIG. 7 is a timing diagram of the local dimming data signal,
the reference clock signal and the first indication signal
transmitted by the local dimming control circuit in FIG. 6 in
accordance with one or more exemplary embodiments of the
invention.
[0024] FIG. 8 a flowchart of a local dimming data transmission
method performed by the local dimming control circuit in FIG. 6 in
accordance with one or more embodiments of the invention.
[0025] FIG. 9 exemplarily illustrates the backlight control circuit
and the backlight module in FIG. 1 in addition to a local dimming
control circuit in accordance with another one or more embodiments
of the invention.
[0026] FIG. 10 is a timing diagram of the local dimming data signal
and the reference clock signal transmitted by the local dimming
control circuit in FIG. 9 in accordance with one or more exemplary
embodiments of the invention.
[0027] FIG. 11 exemplarily illustrates the backlight control
circuit and the backlight module in FIG. 1 in addition to a local
dimming control circuit in accordance with another one or more
embodiments of the invention.
[0028] FIG. 12 is a timing diagram of the local dimming data
signal, the reference clock signal and the first indication signal
transmitted by the local dimming control circuit in FIG. 11 in
accordance with one or more exemplary embodiments of the
invention.
[0029] FIG. 13A exemplarily shows an image to be displayed by the
LCD panel in FIG. 1.
[0030] FIG. 13B shows averaged gray levels of portions of the LCD
panel in FIG. 1 corresponding to the image shown in FIG. 13A.
[0031] FIG. 14A exemplarily shows another image to be displayed by
the LCD panel in FIG. 1.
[0032] FIG. 14B shows averaged gray levels of portions of the LCD
panel in FIG. 1 corresponding to the image shown in FIG. 14A.
[0033] FIG. 15 is a timing diagram of the local dimming data signal
and the reference clock signal transmitted by the local dimming
control circuit in FIG. 2 in accordance with another one or more
exemplary embodiments of the invention.
[0034] FIG. 16 a flowchart of a local dimming data transmission
method performed by the local dimming control circuit in FIG. 2 in
accordance with another one or more embodiments of the
invention.
DETAILED DESCRIPTION
[0035] The detailed explanation of the invention is described as
following. The described preferred embodiments are presented for
purposes of illustrations and description, and they are not
intended to limit the scope of the invention.
[0036] Terms used herein are only used to describe the specific
embodiments, which are not used to limit the claims appended
herewith. Unless limited otherwise, the term "a," "an," "one" or
"the" of the single form may also represent the plural form.
Further, the spatially relative terms are intended to encompass
different orientations of the device in use or operation in
addition to the orientation depicted in the figures. The apparatus
may be otherwise oriented (rotated 90 degrees or at other
orientations) and the spatially relative descriptors used herein
may likewise be interpreted accordingly.
[0037] In the following description and claims, the term "coupled"
along with their derivatives, may be used. In particular
embodiments, "coupled" may be used to indicate that two or more
elements are in direct physical or electrical contact with each
other, or may also mean that two or more elements may not be in
direct contact with each other. "Coupled" may still be used to
indicate that two or more elements cooperate or interact with each
other.
[0038] The document may repeat reference numerals and/or letters in
the various examples. This repetition is for the purpose of
simplicity and clarity and does not in itself dictate a
relationship between the various embodiments and/or configurations
discussed.
[0039] FIG. 1 is a schematic diagram of a display apparatus 100 in
accordance with one or more embodiments of the invention. The
display apparatus 100 includes a liquid crystal display (LCD) panel
110, a data driver 120, a scan driver 130, a timing controller 140,
a backlight control circuit 150 and a backlight module 160. The LCD
panel 110 may be, for example, in a twisted nematic (TN) mode,
in-plane switching (IPS) mode or any other suitable mode. In
addition, the LCD panel 110 includes a plurality of pixel units P,
a plurality of data lines D, and a plurality of scanning lines S.
In the LCD panel 110, the pixel units P form a matrix of rows and
columns. Each pixel unit P includes a switch element T that is
driven by a data line D and a scan line S to be turned on for a
specific time interval, such that the storage capacitor CS is
charged for displaying the corresponding gray level. The data
driver 120 is configured to generate data driving signals to
respectively drive the data lines D to transmit gray level data to
the columns of pixel units P. The scan driver 130 is configured to
generate scan driving signals to drive the scan lines S to control
the switching status of the switch elements T of the pixel units P.
For each pixel unit, the switching status of the switch element T
is turned on during a certain time period, so that the pixel unit P
displays the corresponding gray level. Using the principle of
visual persistence, the human eye can see the complete image in the
display area of the LCD panel 110. The timing controller 140 is
configured to control the scan driver 130 to sequentially drive the
scan lines S of the liquid crystal display panel 110, and to
control the data driver 120 to sequentially send the corresponding
image data to the LCD panel 110 when the scan lines S are
sequentially driven.
[0040] The timing controller 140 is also configured to direct the
backlight control circuit 150 to control the backlight module 160.
The backlight control circuit 150 may be implemented as a
microcontroller. The backlight module 160 is arranged in back of
the LCD panel 110 for providing light source to the LCD panel 110.
The backlight module 160 may be a direct type backlight module 160
in which light source is arranged at the back side thereof and no
light guide plate is needed.
[0041] In some embodiments, the data driver 120, the scan driver
130 and the timing controller 140 are integrated into a single
integrated chip. Furthermore, in certain embodiments, the chip
integrating the functions of the data driver 120, the scan driver
130 and the timing controller 140 may also provide touch detection
function for the LCD panel 110 with an in-cell touch sensor
structure or a touch panel disposed over the LCD panel 110.
[0042] FIG. 2 exemplarily illustrates control of the backlight
control circuit 150 and the backlight module 160 in FIG. 1 in
addition to a local dimming control circuit 142 in accordance with
one or more embodiments of the invention. In the example of FIG. 2,
the backlight module 160 is divided into 4.times.4 light emitting
units BL(1,1)-BL(4,4), i.e., 4 rows and 4 columns of light emitting
units BL(1,1)-BL(4,4). The backlight control circuit 150 is
configured to provide original local dimming data DIM(1)-DIM(N)
respectively for the light emitting units BL(1,1)-BL(4,4) to
irradiate light according to the local dimming data signal LDS and
the reference clock signal CLK from the local dimming control
circuit 142. The local dimming control circuit 142 is configured to
generate local dimming data included in the local dimming data
signal LDS based on the image data to be displayed by the LCD panel
110 and the arrangement of the light emitting units
BL(1,1)-BL(4,4). The local dimming control circuit 142 also
provides the reference clock signal CLK for the backlight control
circuit 150 to obtain the original local dimming data DIM(1)-DIM(N)
from the local dimming data signal LDS. The local dimming control
circuit 142 may be a circuit embedded in the timing controller 140
or externally connected with the timing controller 140 in FIG. 1.
The original local dimming data DIM(1)-DIM(N) include bit data
representing brightness respectively of the light emitting units
BL(1,1)-BL(4,4). The local dimming control circuit 142 and the
backlight control circuit 150 may be integrated into a single
integrated chip for some embodiments.
[0043] FIG. 3A exemplarily illustrates a scanning pattern of the
light emitting units BL(1,1)-BL(4,4). As shown in FIG. 3A, the
scanning pattern is a Z-shaped scanning pattern. In other words,
the first row of light emitting units is scanned first, and then
the second row of light emitting units is scanned, and the like,
and for the same row of light emitting units, the scanning
direction is from left to right.
[0044] FIG. 3B exemplarily illustrates another scanning pattern of
the light emitting units BL(1,1)-BL(4,4). As shown in FIG. 3B, the
scanning pattern is a backwards N-shaped scanning pattern. In other
words, the first column of light emitting units is scanned first,
and then the second column of light emitting units is scanned, and
the like, and for the same column of light emitting units, the
scanning direction is from top to bottom.
[0045] It is noted that the scanning pattern of the backlight
module 160 is not limited to that shown in FIG. 3A or FIG. 3B.
Another scanning pattern, such as zig-zag scanning pattern, may
alternatively be applied for scanning of the backlight module 160.
Further, depending on the scanning pattern of the backlight module
160, the light emitting units BL(1,1)-BL(4,4) are also denoted as
Zones 1-N in the following paragraphs, where N is the total number
of the light emitting units BL(1,1)-BL(4,4) in the backlight module
160.
[0046] FIG. 4 is a timing diagram of the local dimming data signal
LDS and the reference clock signal CLK transmitted by the local
dimming control circuit 142 in accordance with one or more
exemplary embodiments of the invention. The local dimming data
signal LDS includes local dimming data LD(1)-LD(N) respectively
corresponding to Zones 1-N, and the reference clock signal CLK is
in synchronization with the local dimming data signal LDS. In the
case of the backlight module 160 shown in FIG. 2, N is 16. Each bit
in the local dimming data signal LDS may correspond to a clock
period of the reference clock signal CLK. In particular, blank
intervals between the adjacent local dimming data LD(1)-LD(N) are
set in the local dimming data signal LDS, such that the adjacent
local dimming data LD(1)-LD(N) can be distinguished by the
backlight control circuit 150. Each local dimming data LD(1)-LD(N)
has an indication bit CBit for indicating whether it is a reduced
local dimming data from the corresponding original local dimming
data DIM(1)-DIM(N). The duration of each of the blank intervals
between the adjacent local dimming data LD(1)-LD(N) may be, for
example, a clock period of the reference clock signal CLK.
[0047] In specific, the local dimming control circuit 142 firstly
generates original local dimming data DIM(1)-DIM(N) with equal bit
length. Each original local dimming data DIM(1)-DIM(N) includes
most significant bits and least significant bits. That is, the
original local dimming data DIM(1) includes most significant bits
MSB_DATA(1) and least significant bits LSB_DATA(1), the original
local dimming data DIM(2) includes most significant bits
MSB_DATA(2) and least significant bits LSB_DATA(2), and the like.
In some embodiments, for each original local dimming data
DIM(1)-DIM(N), the number of each of most and least significant
bits is 8. After the original local dimming data DIM(1)-DIM(N) are
generated, the dimming control circuit 140 adds an indication bit
CBit of "1" to the original local dimming data DIM(1) with the most
significant bits MSB_DATA(1) and the least significant bits
LSB_DATA(1) to form the local dimming data LD(1) for being
transmitted to the backlight control circuit 150, and then compares
the original local dimming data DIM(i-1) and DIM(i) for all i from
2 to N. If the most significant bits MSB_DATA(i-1) and MSB_DATA(i)
of the original local dimming data DIM(i-1) and DIM(i) are
identical, the most significant bits MSB_DATA(i) of the original
local dimming data DIM(i) are removed, and an indication bit CBit
of "0" is added to the least significant bits LSB_DATA(i) of the
original local dimming data DIM(i) to form the local dimming data
LD(i) for being transmitted to the backlight control circuit 150.
Otherwise, if the most significant bits MSB_DATA(i-1) and
MSB_DATA(i) of the original local dimming data DIM(i-1) and DIM(i)
are not identical, an indication bit CBit of "1" is added to the
original local dimming data DIM(i) with the most significant bits
MSB_DATA(i) and the least significant bits LSB_DATA(i) to form the
local dimming data LD(i) for being transmitted to the backlight
control circuit 150.
[0048] For example, in a case where the most significant bits
MSB_DATA(1) and MSB_DATA(2) of the original local dimming data
DIM(1) and DIM(2) are identical, the local dimming control circuit
142 removes the most significant bits MSB_DATA(2) of the original
local dimming data DIM(2), and an indication bit CBit of "0" is
added to the least significant bits LSB_DATA(2) of the original
local dimming data DIM(2) to form the local dimming data LD(2); in
a case where the most significant bits MSB_DATA(3) and MSB_DATA(4)
of the original local dimming data DIM(3) and DIM(4) are not
identical, an indication bit CBit of "1" is added to the original
local dimming data DIM(4) to form the local dimming data LD(4).
[0049] FIG. 5 is a flowchart of a local dimming data transmission
method 200 performed by the local dimming control circuit 142 in
FIG. 2 in accordance with one or more embodiments of the invention.
In the beginning of the local dimming data transmission method 200,
a counter i is initialized to 1 before Step S202 is performed for
the first time. In Step S202, the local dimming control circuit 142
transmits local dimming data LD(i) with an indication bit CBit of
"1" and the most significant bits MSB_DATA(i) and the least
significant bits LSB_DATA(i) of the original local dimming data
DIM(i). After Step S202 is performed, the local dimming data
transmission method 200 proceeds to Step S204, in which the local
dimming control circuit 142 checks whether all local dimming data
respectively corresponding to the light emitting units
BL(1,1)-BL(4,4) are transmitted (i.e. determines whether the
counter i is equal to N). If yes, the local dimming data
transmission method 200 ends; else, the local dimming data
transmission method 200 proceeds to Step S206, in which the counter
i is incremented by 1. In Step S208, the local dimming control
circuit 142 compares the most significant bits MSB_DATA(i-1) and
MSB_DATA(i) respectively of the original local dimming data
DIM(i-1) and DIM(i) to determine whether the most significant bits
MSB_DATA(i-1) and MSB_DATA(i) are identical. If yes, the local
dimming data transmission method 200 proceeds to Step S210, in
which the local dimming control circuit 142 transmits local dimming
data LD(i) with an indication bit CBit of "0" and only the least
significant bits LSB_DATA(i) of the original local dimming data
DIM(i) but without the most significant bits MSB_DATA(i) of the
original local dimming data DIM(i), and then proceeds back to Step
S204; else, the local dimming data transmission method 200 proceeds
back to Step S202.
[0050] FIG. 6 exemplarily illustrates the backlight control circuit
150 and the backlight module 160 in FIG. 1 in addition to a local
dimming control circuit 142 in accordance with another one or more
embodiments of the invention. In the example of FIG. 6, the
backlight control circuit 150 is configured to provide original
local dimming data DIM(1)-DIM(N) respectively for the light
emitting units BL(1,1)-BL(4,4) to irradiate light according to the
local dimming data signal LDS, the reference clock signal CLK and a
first indication signal ID1 from the local dimming control circuit
142. The local dimming control circuit 142 is configured to
generate local dimming data included in the local dimming data
signal LDS based on the image data to be displayed by the LCD panel
110 and the arrangement of the light emitting units
BL(1,1)-BL(4,4). The local dimming control circuit 142 also
provides the reference clock signal CLK and the first indication
signal ID1 for the backlight control circuit 150 to obtain the
original local dimming data DIM(1)-DIM(N) from the local dimming
data signal LDS.
[0051] In particular, the first indication signal ID1 is used to
indicate the backlight control circuit 150 of whether the bits of
the currently received local dimming data are reduced from those of
the original local dimming data corresponding to the same light
emitting unit. For example, the first indication signal ID1 at high
indicates that the bits of the currently received local dimming
data are the same as those of the original local dimming data
corresponding to the same light emitting unit, and when receiving
such first indication signal ID1, the backlight control circuit
stores the most significant bits of the currently received local
dimming data; the first indication signal ID1 at low indicates that
the bits of the currently received local dimming data are reduced
from those of the original local dimming data corresponding to the
same light emitting unit, i.e., the currently received local
dimming data only have least significant bits, and when receiving
such first indication signal ID1, the backlight control circuit
combines the last stored most significant bits and the currently
received local dimming data into a combined local dimming data for
the same light emitting unit.
[0052] FIG. 7 is a timing diagram of the local dimming data signal
LDS, the reference clock signal CLK and the first indication signal
ID1 transmitted by the local dimming control circuit 142 in FIG. 6
in accordance with one or more exemplary embodiments of the
invention. The dimming control circuit 140 firstly transmits the
original local dimming data DIM(1) as the local dimming data LD(1)
and outputs the first indication signal ID1 as high to the
backlight control circuit 150 for Zone 1, and then compares the
original local dimming data DIM(i-1) and DIM(i) for all i from 2 to
N. If the most significant bits MSB_DATA(i-1) and MSB_DATA(i) of
the original local dimming data DIM(i-1) and DIM(i) are identical,
the most significant bits MSB_DATA(i) of the original local dimming
data DIM(i) is removed, and then only the least significant bits
LSB_DATA(i) of the original local dimming data DIM(i) are
transmitted as the local dimming data LD(i) to the backlight
control circuit 150 for Zone i, and the first indication signal ID1
is outputted as low. Otherwise, if the most significant bits
MSB_DATA(i-1) and MSB_DATA(i) of the original local dimming data
DIM(i-1) and DIM(i) are not identical, the full original local
dimming data DIM(i) with the most significant bits MSB_DATA(i) and
the least significant bits LSB_DATA(i) are transmitted as the local
dimming data LD(i+1) to the backlight control circuit 150 for Zone
i, and the first indication signal ID1 is outputted as high.
[0053] For example, in a case where the most significant bits
MSB_DATA(1) and MSB_DATA(2) of the original local dimming data
DIM(1) and DIM(2) are identical, as shown in FIG. 7, only the least
significant bits LSB_DATA(2) of the original local dimming data
DIM(2) are transmitted as the local dimming data LD(2) for Zone 2,
and the first indication signal ID1 is set as low; in a case where
the most significant bits MSB_DATA(3) and MSB_DATA(4) of the
original local dimming data DIM(3) and DIM(4) are not identical, as
shown in FIG. 4, the full original local dimming data DIM(4) with
the most significant bits MSB_DATA(4) and the least significant
bits LSB_DATA(4) are transmitted as the local dimming data LD(4)
for Zone 4, and the first indication signal ID1 is set as high.
[0054] FIG. 8 is a flowchart of a local dimming data transmission
method 300 performed by the local dimming control circuit 142 in
FIG. 6 in accordance with one or more embodiments of the invention.
In the beginning of the local dimming data transmission method 300,
a counter i is initialized to 1 before Step S302 is performed for
the first time. In Step S302, the local dimming control circuit 142
transmits local dimming data LD(i) with the most significant bits
MSB_DATA(i) and the least significant bits LSB_DATA(i) of the
original local dimming data DIM(i), and outputs the first
indication signal ID1 as high. After Step S302 is performed, the
local dimming data transmission method 300 proceeds to Step S304,
in which the local dimming control circuit 142 checks whether all
local dimming data respectively corresponding to the light emitting
units BL(1,1)-BL(4,4) are transmitted (i.e. determines whether the
counter i is equal to N). If yes, the local dimming data
transmission method 300 ends; else, the local dimming data
transmission method 300 proceeds to Step S306, in which the counter
i is incremented by 1. In Step S308, the local dimming control
circuit 142 compares the most significant bits MSB_DATA(i-1) and
MSB_DATA(i) respectively of the original local dimming data
DIM(i-1) and DIM(i) to determine whether the most significant bits
MSB_DATA(i-1) and MSB_DATA(i) are identical. If yes, the local
dimming data transmission method 300 proceeds to Step S310, in
which the local dimming control circuit 142 transmits only the
least significant bits LSB_DATA(i) of the original local dimming
data DIM(i) as the local dimming data LD(i) but without the most
significant bits MSB_DATA(i) of the original local dimming data
DIM(i), and outputs the first indication signal ID1 as low, and
then proceeds back to Step S304; else, the local dimming data
transmission method 300 proceeds back to Step S302.
[0055] FIG. 9 exemplarily illustrates the backlight control circuit
150 and the backlight module 160 in FIG. 1 in addition to a local
dimming control circuit 142 in accordance with another one or more
embodiments of the invention. In the example of FIG. 9, the
backlight control circuit 150 is configured to provide original
local dimming data DIM(1)-DIM(N) respectively for the light
emitting units BL(1,1)-BL(4,4) to irradiate light according to the
local dimming data signal LDS, the reference clock signal CLK and a
second indication signal ID2 from the local dimming control circuit
142. The local dimming control circuit 142 is configured to
generate local dimming data included in the local dimming data
signal LDS based on the image data to be displayed by the LCD panel
110 and the arrangement of the light emitting units
BL(1,1)-BL(4,4). The local dimming control circuit 142 also
provides the reference clock signal CLK and the second indication
signal ID2 for the backlight control circuit 150 to obtain the
original local dimming data DIM(1)-DIM(N) from the local dimming
data signal LDS.
[0056] In particular, the second indication signal ID2 is used to
indicate the backlight control circuit 150 of the number of bits of
the least significant bits in each local dimming data. For example,
the second indication signal ID2 at high indicates that the number
of most significant bits of each local dimming data is 10 and the
number of least significant bits of each local dimming data is 6,
while the second indication signal ID2 at low indicates that the
number of most significant bits and the number of least significant
bits of each local dimming data are all 8. It is noted that the
number of most significant bits and the number of least significant
bits of each local dimming data herein are merely exemplarily
examples and can be determined according to various design
parameters and application requirements.
[0057] FIG. 10 is a timing diagram of the local dimming data signal
LDS and the reference clock signal CLK transmitted by the local
dimming control circuit 142 in FIG. 9 in a case where the second
indication signal ID2 is outputted as high in accordance with one
or more exemplary embodiments of the invention. The dimming control
circuit 140 firstly adds an indication bit CBit of "1" to the
original local dimming data DIM(1) with the 10-bit most significant
bits MSB_DATA(1) and the 6-bit least significant bits LSB_DATA(1)
to form the local dimming data LD(1) for being transmitted to the
backlight control circuit 150, and then compares the original local
dimming data DIM(i-1) and DIM(i) for all i from 2 to N. If the
10-bit most significant bits MSB_DATA(i-1) and MSB_DATA(i) of the
original local dimming data DIM(i-1) and DIM(i) are identical, the
10-bit most significant bits MSB_DATA(i) of the original local
dimming data DIM(i) are removed, and an indication bit CBit of "0"
is added to the 6-bit least significant bits LSB_DATA(i) of the
original local dimming data DIM(i) to form the local dimming data
LD(i) for being transmitted to the backlight control circuit 150.
Otherwise, if the 10-bit most significant bits MSB_DATA(i-1) and
MSB_DATA(i) of the local dimming data LD(i-1) and LD(i) are not
identical, an indication bit CBit of "1" is added to the original
local dimming data DIM(i) with the 10-bit most significant bits
MSB_DATA(i) and the 6-bit least significant bits LSB_DATA(i) to
form the local dimming data LD(i) for being transmitted to the
backlight control circuit 150.
[0058] FIG. 11 exemplarily illustrates the backlight control
circuit 150 and the backlight module 160 in FIG. 1 in addition to a
local dimming control circuit 142 in accordance with another one or
more embodiments of the invention. In the example of FIG. 11, the
backlight control circuit 150 is configured to provide original
local dimming data DIM(1)-DIM(N) respectively for the light
emitting units BL(1,1)-BL(4,4) to irradiate light according to the
local dimming data signal LDS, the reference clock signal CLK, the
first indication signal ID1 and the second indication signal ID2
from the local dimming control circuit 142. The local dimming
control circuit 142 is configured to generate local dimming data
included in the local dimming data signal LDS based on the image
data to be displayed by the LCD panel 110 and the arrangement of
the light emitting units BL(1,1)-BL(4,4). The local dimming control
circuit 142 also provides the reference clock signal CLK, the first
indication signal ID1 and the second indication signal ID2 for the
backlight control circuit 150 to obtain the original local dimming
data DIM(1)-DIM(N) from the local dimming data signal LDS.
[0059] FIG. 12 is a timing diagram of the local dimming data signal
LDS, the reference clock signal CLK and the first indication signal
ID1 transmitted by the local dimming control circuit 142 in FIG. 11
in a case where the second indication signal ID2 is outputted as
high in accordance with one or more exemplary embodiments of the
invention. The dimming control circuit 140 firstly transmits the
original local dimming data DIM(1) with the 10-bit most significant
bits MSB_DATA(1) and the 6-bit least significant bits LSB_DATA(1)
as the local dimming data LD(1) and outputs the first indication
signal ID1 as high to the backlight control circuit 150 for Zone 1,
and then compares the original local dimming data DIM(i-1) and
DIM(i) for all i from 2 to N. If the 10-bit most significant bits
MSB_DATA(i-1) and MSB_DATA(i) of the original local dimming data
DIM(i-1) and DIM(i) are identical, the 10-bit most significant bits
MSB_DATA(i) of the original local dimming data DIM(i) are removed,
and then only the 6-bit least significant bits LSB_DATA(i) of the
original local dimming data DIM(i) are transmitted as the local
dimming data LD(i) to the backlight control circuit 150 for Zone i,
and the first indication signal ID1 is outputted as low. Otherwise,
if the 10-bit most significant bits MSB_DATA(i-1) and MSB_DATA(i)
of the original local dimming data DIM(i-1) and DIM(i) are not
identical, the full original local dimming data DIM(i) with the
10-bit most significant bits MSB_DATA(i) and the 6-bit least
significant bits LSB_DATA(i) are transmitted as the local dimming
data LD(i) to the backlight control circuit 150 for Zone i, and the
first indication signal ID1 is outputted as high.
[0060] FIG. 13A exemplarily shows an image to be displayed by the
LCD panel 110, and FIG. 13B shows average gray levels of portions
of the LCD panel 110 corresponding to the image shown in FIG. 13A.
The display area of the LCD panel 110 is divided into several
portions respectively corresponding to the light emitting units
BL(1,1)-BL(4,4) of the backlight module 160 that adopts Z-shaped
scanning. In particular, the local dimming control circuit 142
detects averaged gray levels of the sub-images of the image
respectively corresponding to the light emitting units
BL(1,1)-BL(4,4), and then converts these gray levels into original
local dimming data DIM(1)-DIM(N) respectively for the light
emitting units BL(1,1)-BL(4,4). As shown in FIGS. 13A-13B, the
relatively bright portions of the LCD panel 110 respectively
corresponding to relatively bright sub-images have high gray
levels, while the relatively dark portions of the LCD panel 110
respectively corresponding to relatively dark sub-images have low
gray levels.
[0061] In the example shown in FIG. 13B, the original local dimming
data DIM(1)-DIM(6) have the same most significant bits, the
original local dimming data DIM(7)-DIM(8) have the same most
significant bits, the original local dimming data DIM(9)-DIM(10)
have the same most significant bits, and the original local dimming
data DIM(11)-DIM(16) have the same most significant bits. Also, the
most significant bits MSB_DATA(1) are different from the most
significant bits MSB_DATA(7), the most significant bits MSB_DATA(7)
are different from the most significant bits MSB_DATA(9), and the
most significant bits MSB_DATA(9) are different from the most
significant bits MSB_DATA(11). If the local dimming control circuit
142 and the backlight control circuit 150 in FIG. 1 are applied as
well as the local dimming data transmission method 200, the total
number of bits of the local dimming data LD(1)-LD(16) transmitted
from the local dimming control circuit 142 to the backlight control
circuit 150 is 4.times.17+12.times.9=176, and the local dimming
data compression ratio is (16.times.16)/176=1.45.
[0062] FIG. 14A exemplarily shows another image to be displayed by
the LCD panel 110, and FIG. 14B shows averaged gray levels of
portions of the LCD panel 110 corresponding to the image shown in
FIG. 14A. In the example shown in FIG. 14B, all of the original
local dimming data DIM(1)-DIM(16) have the same most significant
bits. If the local dimming control circuit 142 and the backlight
control circuit 150 in FIG. 1 are applied as well as the local
dimming data transmission method 200, the total number of bits of
the local dimming data LD(1)-LD(16) transmitted from the local
dimming control circuit 142 to the backlight control circuit 150 is
1x17+15x9=152, and the local dimming data compression ratio is
(16.times.16)/152=1.68.
[0063] FIG. 15 is a timing diagram of local dimming data signal and
a reference clock signal transmitted by the local dimming control
circuit in FIG. 2 in accordance with another one or more exemplary
embodiments of the invention. The local dimming control circuit 142
determines whether the remaining time after local dimming data
compression is sufficient for transmitting initial code data
Init_Code to the backlight control circuit 150 for refreshing the
stored initial code data. The initial code data Init_Code may
include, but is not limited to, parameters of LED brightness
control, LED frequency spectra, current limiting, short-circuit
protection and/or error report. If the remaining time is
sufficient, the local dimming control circuit 142 transmits the
initial code data Init_Code to the backlight control circuit 150
subsequent to the local dimming data LD(1)-LD(N).
[0064] FIG. 16 is a flowchart of a local dimming data transmission
method 200 performed by the local dimming control circuit 142 in
accordance with one or more embodiments of the invention. The
difference between the local dimming data transmission methods 200
and 400 is, in the local dimming data transmission method 400, if
all local dimming data respectively corresponding to the light
emitting units BL(1,1)-BL(4,4) are transmitted, Step S402 is then
performed to determine whether the remaining time is longer than
the predetermined threshold corresponding to the time required for
transmitting the initial code data Init_Code. If yes, Step S404 is
performed, in which the local dimming control circuit 142 transmits
the initial code data Init_Code to the backlight control circuit
150, and then the local dimming data transmission method 400
ends.
[0065] It will be apparent to those skilled in the art that various
modifications and variations can be made to the structure of the
invention without departing from the scope or spirit of the
invention. In view of the foregoing, it is intended that the
invention cover modifications and variations of this invention
provided they fall within the scope of the following claims.
* * * * *