WO2007011086A1 - Method and apparatus for converting gradation data in lcd - Google Patents

Method and apparatus for converting gradation data in lcd Download PDF

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Publication number
WO2007011086A1
WO2007011086A1 PCT/KR2005/002315 KR2005002315W WO2007011086A1 WO 2007011086 A1 WO2007011086 A1 WO 2007011086A1 KR 2005002315 W KR2005002315 W KR 2005002315W WO 2007011086 A1 WO2007011086 A1 WO 2007011086A1
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WIPO (PCT)
Prior art keywords
gradation data
gradation
data
previous
input
Prior art date
Application number
PCT/KR2005/002315
Other languages
French (fr)
Inventor
Jong-Sik Lee
Hong-Kil Kim
Original Assignee
Hyvix Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hyvix Co., Ltd. filed Critical Hyvix Co., Ltd.
Priority to PCT/KR2005/002315 priority Critical patent/WO2007011086A1/en
Publication of WO2007011086A1 publication Critical patent/WO2007011086A1/en

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Classifications

    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/36Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
    • G09G3/3611Control of matrices with row and column drivers
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00Control of display operating conditions
    • G09G2320/02Improving the quality of display appearance
    • G09G2320/0252Improving the response speed
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2340/00Aspects of display data processing
    • G09G2340/16Determination of a pixel data signal depending on the signal applied in the previous frame
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2360/00Aspects of the architecture of display systems
    • G09G2360/18Use of a frame buffer in a display terminal, inclusive of the display panel

Definitions

  • the present invention relates to a liquid crystal display LCD and, more
  • the LCD consists primarily of two glass plates, on which
  • the LCD has been widely used owing to its
  • the LCD may deteriorate vividness of the moving picture since it
  • the present invention is devised to shorten the response speed of the LCD
  • the method for converting gradation data in LCD comprising the steps of:
  • step 2 generating new gradation data based on the correction value; and fixing
  • step 5 the gradation data obtained in step 5 as gradation data for driving the LCD.
  • the apparatus for converting gradation data in LCD comprising: a buffer for
  • the data converting means generating a correction value
  • the coefficient value being set according to level ranges of the input
  • the apparatus for converting gradation data in LCD comprising: a buffer for storing
  • the data converting means generating a correction value
  • the coefficient value being set according to level ranges of the input
  • the apparatus for converting gradation data in LCD comprising: a buffer for storing
  • gradation data input from outside a frame memory for storing previous gradation
  • a gradation data storing means including the previous
  • control means for reading out predetermined gradation data from the gradation
  • the apparatus for converting gradation data in LCD comprising: a buffer for storing
  • a gradation data storing means including the
  • gradation data storing means based on the input gradation data and the previous
  • gradation data storing means storing the gradation data storing means storing the
  • the coefficient value being set according to level ranges of the input gradation
  • the coefficient value is set to a larger value in case that the
  • level of the gradation data is low rather than in case that the level of the gradation
  • the coefficient value is set to: KO, if the previous gradation data
  • Fig. 1 is a block diagram showing an example of an LCD driving apparatus
  • Fig. 2 is a flowchart illustrating a series of operations for gradation data
  • Fig. 3 is a characteristic curve, for explaining the basic concept of the
  • Fig. 4 is a block diagram depicting an example of an apparatus for
  • Fig. 1 is a block diagram showing an example of an LCD driving apparatus
  • Fig. 1 The apparatus shown in Fig. 1 is the same one disclosed in the US Patent Application No. 10/395,663 by the present inventor
  • the LCD driving apparatus in Fig. 1 comprises a processor 10, an LCD
  • the processor 10 processes
  • the LCD driving part 20 drives the LCD based on driving signals output
  • the data converting device 30 includes a recording buffer 31 , a data
  • the recording buffer 31 stores
  • the frame memory 33 stores
  • the data converting part 32 compares the
  • the gradation data converted in this manner is stored in the frame memory 33
  • processing red R, green G and blue B data has substantially the same configuration and its operation is also same with each other.
  • Fig. 2 is a flowchart illustrating a series of operations for gradation data
  • the processor 10 stores gradation data to be displayed on
  • the data converting part 32 reads out one
  • the new gradation data N is larger than the maximum gradation value
  • the minimum value is set as a new gradation value N
  • the data converting part 32 executes data conversion for the gradation data stored in the recording buffer 31 and the frame memory 33
  • Patent Application No. 10/395,663 has a defect that cannot enhance the response
  • Fig. 3 is a characteristic curve showing a characteristic of transmitted light
  • the LCD has a characteristic that the transmitted light amount is not varied
  • the LCD has a characteristic that the transmitted light amount increases
  • the present invention is to
  • selecting the coefficient K refers to both the present gradation data
  • gradation data R are classified into three ranges such as low-gradation data,
  • the gradation data for red R, green G and blue B are formed in the unit of 5-bit
  • gradation is set to a range of 0 to 11 levels, the middle-gradation is 12 to 23 levels
  • the high-gradation is 24 to 32 levels.
  • the coefficient is set to
  • the input gradation data R is in the middle-gradation range, or if
  • the previous gradation data P is in the middle-gradation range
  • the coefficient is set to "K2";
  • gradation data R is in the high-gradation range, the coefficient is set to "K3", the
  • the data converting part 32 preferentially sets the coefficient
  • the input gradation data is converted by executing
  • converting part 32 converts the input gradation data through a predetermined
  • Fig. 4 is a block diagram depicting an apparatus for converting gradation
  • FIG. 4 corresponds to the data converting device 30 in Fig.
  • a ROM table 51 storing plural gradation data to be displayed on
  • the ROM table 51 includes first to fourth gradation data
  • the first to fourth gradation data storing parts 511 to 514 store gradation
  • the gradation data stored in the recording buffer 31 the gradation data stored in the recording buffer 31.
  • storing part 511 stores gradation data to be displayed on the LCD against
  • the second gradation data storing part 512 stores gradation data to be
  • the third gradation data storing part 513 stores gradation data to be
  • input gradation data R is in the middle-gradation range, or in case that the
  • previous gradation data P is in the middle-gradation range and the input gradation
  • the fourth gradation data storing part 514 stores gradation data to
  • gradation data stored are to be adjusted appropriately based on the response
  • a control part 50 in Fig. 4 corresponds to the data converting part 32 in Fig.
  • control part 50 does not operate based on the previous gradation
  • part 50 stores the gradation data read out in a predetermined region of the frame
  • the control part 50 reads out previous gradation data P, i.e., the gradation data
  • control part 50 reads out appropriate gradation data from
  • the present invention can provide a high response of LCD by
  • PCT International Application No. PCT/KR2005/000725 has a reading means for
  • the present invention executes the gradation data
  • the prevent invention can raise the response of

Abstract

Disclosed relates to a method and an apparatus for converting gradation data in LCD that provides a high response of LCD by converting gradation data applied to LCD appropriately. According to the present invention, a data converting part 32 converts gradation data, newly input and stored in a recording buffer 31, based on previous gradation data stored in a frame memory 33 and, the converted gradation data, i.e., the gradation data to be displayed newly on the LCD, is stored in the frame memory 33. Especially, the data converting part 32 executes gradation conversion based on the gradation levels that input gradation data and previous gradation data have. Accordingly, the prevent invention can raise the response of the LCD all the more by executing most optimum gradation conversion in accordance with characteristics of the LCD and, further, removes after-images shown on the LCD efficiently.

Description

METHOD AND APPARATUS FOR CONVERTING GRADATION DATA
IN LCD
Technical Field
The present invention relates to a liquid crystal display LCD and, more
particularly, to a method and an apparatus for converting gradation data in LCD
that improves image quality output from the LCD by executing most optimum
gradation data conversion in accordance with characteristics of the LCD.
Background Art
In general, the LCD consists primarily of two glass plates, on which
transparent electrodes are formed, with some liquid crystal material filled between
them. When a predetermined electric field is applied to the transparent electrodes,
the electric field arranges and rotates the liquid crystal material in a specific
direction so as to control the quantity of lights transmitting the liquid crystal
material, thus displaying images. The LCD has been widely used owing to its
merits that it is thin in thickness and light in weight.
However, the LCD may deteriorate vividness of the moving picture since it
has a long response time against input data under the influence of cumulative
response, that is, since an image of a previous screen does not immediately
disappear but is overlapped with a subsequent image, which is called the after¬
image phenomenon. To solve this problem, the present inventor and applicant have disclosed
US Patent Application No. 10/395,663 and PCT International Application No.
PCT/KR2004/000406 titled: Method and Apparatus for Converting Gradation Data
in STN LCD, and PCT International Application No. PCT/KR2005/000725 titled:
Method and Apparatus for Converting Gradation Data in TFT LCD. These
applications are directed to a method and an apparatus for shortening the
response speed of the LCD by converting gradation data for displaying images to
increase time-sequential variation range of gradation data applied to the LCD.
Disclosure of Invention
The present invention is devised to shorten the response speed of the LCD
by improving the inventions disclosed in the US Patent Application No. 10/395,663
with the PCT International Application No. PCT/KR2004/000406, and the PCT
International Application No. PCT/KR2005/000725 by the present inventor and
applicant.
In accordance with a first aspect of the present invention, there is provided,
in a method for converting gradation data, which is applied to an apparatus for
converting gradation data in an LCD having a data converting device for
converting gradation data for driving the LCD and executed by the data converting
device, the method for converting gradation data in LCD comprising the steps of:
receiving input gradation data for driving the LCD; setting a coefficient value for
gradation conversion based on the input gradation data and a level value of previous gradation data that is displayed previously on the LCD and corresponds
to the input gradation data; calculating a difference value between the input
gradation data and the previous gradation data; computing a correction value
based on the difference value obtained in step 3 and the coefficient value set in
step 2; generating new gradation data based on the correction value; and fixing
the gradation data obtained in step 5 as gradation data for driving the LCD.
Besides, according to a second aspect of the present invention, there is
provided, in an apparatus for converting gradation data to be supplied to an
LCD, the apparatus for converting gradation data in LCD comprising: a buffer for
storing gradation data input from outside; a frame memory for storing previous
gradation data applied to the LCD; and a data converting means for generating
gradation data to be newly displayed based on the input gradation data and the
previous gradation data, the data converting means generating a correction value
by subtracting the previous gradation data from the corresponding input gradation
data and by multiplying a subtraction result value by a predetermined coefficient
value and, the coefficient value being set according to level ranges of the input
gradation data and the previous gradation data.
In addition, according to a third aspect of the present invention, there is
provided, in an apparatus for converting gradation data to be supplied to an LCD,
the apparatus for converting gradation data in LCD comprising: a buffer for storing
gradation data input from outside; a reading means for reading out previous
gradation data from the LCD; and a data converting means for generating gradation data to be newly displayed based on the input gradation data and the
previous gradation data, the data converting means generating a correction value
by subtracting the previous gradation data from the corresponding input gradation
data and by multiplying a subtraction result value by a predetermined coefficient
value and, the coefficient value being set according to level ranges of the input
gradation data and the previous gradation data.
Furthermore, according to a fourth aspect of the present invention, there is
provided, in an apparatus for converting gradation data to be supplied to an LCD,
the apparatus for converting gradation data in LCD comprising: a buffer for storing
gradation data input from outside; a frame memory for storing previous gradation
data applied to the LCD; a gradation data storing means including the previous
gradation data and gradation data corresponding to the input gradation data; and
a control means for reading out predetermined gradation data from the gradation
data storing means based on the input gradation data and the previous gradation
data and storing the gradation data read out in the frame memory, the gradation
data storing means storing the gradation data obtained by multiplying a difference
value between the input gradation data and the previous gradation data by a
predetermined coefficient value and adding a multiplication result value to the
previous gradation data and, the coefficient value being set according to level
ranges of the input gradation data and the previous gradation data.
Moreover, according to a fifth aspect of the present invention, there is
provided, in an apparatus for converting gradation data to be supplied to an LCD, the apparatus for converting gradation data in LCD comprising: a buffer for storing
gradation data input from outside; a reading means for reading out previous
gradation data from the LCD; a gradation data storing means including the
previous gradation data and gradation data corresponding to the input gradation
data; and a control means for reading out predetermined gradation data from the
gradation data storing means based on the input gradation data and the previous
gradation data and storing the gradation data read out in the frame memory, the
gradation data storing means storing the gradation data storing means storing the
gradation data obtained by multiplying a difference value between the input
gradation data and the previous gradation data by a predetermined coefficient
value and adding a multiplication result value to the previous gradation data, and,
the coefficient value being set according to level ranges of the input gradation
data and the previous gradation data.
Meanwhile, the coefficient value is set to a larger value in case that the
level of the gradation data is low rather than in case that the level of the gradation
data is high.
Besides, the coefficient value is set to: KO, if the previous gradation data
and the input gradation data are all in a low-gradation range; K1 , if the previous
gradation data and the input gradation data are all in a middle-gradation range; K2,
if the previous gradation data is in the low-gradation range and the input gradation
data is in the middle-gradation range, or if the previous gradation data is in the
middle-gradation range and the input gradation data is in the low-gradation range; K3, if one of the previous gradation data and the input gradation data is in a high-
gradation range; and the method satisfies a condition of K0>K1>K2>K3.
Brief Description of Drawings
Fig. 1 is a block diagram showing an example of an LCD driving apparatus
that the present invention is applied to;
Fig. 2 is a flowchart illustrating a series of operations for gradation data
conversion executed by the data converting part 32 in Fig. 1 ;
Fig. 3 is a characteristic curve, for explaining the basic concept of the
present invention, showing a characteristic of transmitted light amount according
to gradation voltage applied in the LCD; and
Fig. 4 is a block diagram depicting an example of an apparatus for
converting gradation data in LCD in accordance with the present invention.
Best Mode for Carrying Out the Invention
Reference will now be made in detail to the preferred embodiments of the
present invention, examples of which are illustrated in the accompanying
drawings.
First, the basic concept of the present invention will be described
hereinafter.
Fig. 1 is a block diagram showing an example of an LCD driving apparatus
that the present invention is applied to. The apparatus shown in Fig. 1 is the same one disclosed in the US Patent Application No. 10/395,663 by the present inventor
and applicant.
The LCD driving apparatus in Fig. 1 comprises a processor 10, an LCD
driving part 20 and a data converting device 30. The processor 10 processes
image data to generate and output gradation data corresponding to respective
pixels. The LCD driving part 20 drives the LCD based on driving signals output
from the data converting device 30. Besides, the data converting device 30
converts the gradation data input from the processor 10 appropriately and applies
the converted data to the LCD driving part 20.
The data converting device 30 includes a recording buffer 31 , a data
converting part 32 and a frame memory 33. The recording buffer 31 stores
gradation data input from the processor 10. The frame memory 33 stores
gradation data for driving the LCD. The data converting part 32 compares the
gradation data stored in the recording buffer 31 with the previous gradation data
stored in the frame memory 33, i.e., the gradation data being displayed on the
LCD at present, and converts the gradation data stored in the recording buffer 31.
The gradation data converted in this manner is stored in the frame memory 33
and will be displayed subsequently on the LCD.
Besides, while three data converting parts 32 are required to process red R,
green G and blue B data respectively, only one data converting part 32 is depicted
in the figure to simplify the explanation. Each of the data converting parts 32 for
processing red R, green G and blue B data has substantially the same configuration and its operation is also same with each other.
Fig. 2 is a flowchart illustrating a series of operations for gradation data
conversion executed by the data converting part 32.
In Figs. 1 and 2, the processor 10 stores gradation data to be displayed on
the LCD in the recording buffer 31. The data converting part 32 reads out one
gradation data R stored in the recording buffer 31 and one gradation data P stored
in the frame memory 33, i.e., the gradation data previously displayed on the LCD
(ST 1 and ST2), and calculates a difference value e (ST 3).
Next, the data converting part 32 multiplies the obtained difference value e
by a predetermined coefficient K to calculate a correction value. Here, the
coefficient K, a tentative value, is set to a positive value that is larger than 1 , the
value being set according to the response characteristic of the LCD that the
present invention is applied to.
Subsequently, the data converting part 32 adds the obtained correction
value to the previous gradation data P to calculate new gradation data N (ST 4).
If the new gradation data N is obtained, the data converting part 32
determines whether the new gradation data N is larger than the maximum
gradation value or smaller than the minimum gradation value (ST 5 and ST 6). If
the new gradation data N is larger than the maximum gradation value, the
maximum value is set as a new gradation value N, whereas, if smaller than the
minimum gradation value, the minimum value is set as a new gradation value N
(ST 7 and ST 8). The data converting part 32 executes data conversion for the gradation data stored in the recording buffer 31 and the frame memory 33
continuously and repeatedly until the display operations are terminated.
However, the method for converting gradation data disclosed in the US
Patent Application No. 10/395,663 has a defect that cannot enhance the response
characteristic of the LCD efficiently since the coefficient K for converting gradation
is fixed to a single value as will be described hereinafter.
Fig. 3 is a characteristic curve showing a characteristic of transmitted light
amount according to gradation voltage applied in a general LCD. As shown in the
figure, the LCD has a characteristic that the transmitted light amount is not varied
linearly but increased nonlinearly according as the gradation voltage increases. To
wit, the LCD has a characteristic that the transmitted light amount increases
slowly in case that the gradation voltage is low, whereas, it increases rapidly
where the gradation voltage is high, according as the gradation value increases,
respectively.
Meanwhile, as described above in detail, the variation of the transmitted
light amount against the variation of the gradation voltage applied is not made
promptly, thus generating the after-image on the LCD. According to the present
inventor's study, the after-image occurs primarily in low-gradation range, where
the variation of the transmitted light amount against the variation of the gradation
voltage is weak, rather than in the high-gradation range, where the variation of the
transmitted light amount against the variation of the gradation voltage is made
sharply. Accordingly, to eliminate the after-image observed on the LCD efficiently, it
is required to vary the gradation voltage sharply in the low-gradation range. That
is, it is required to set the coefficient K, depicted in the flowchart of Fig. 2, to a
large value.
However, if setting the coefficient K to a large value, the gradation data that
exceeds a limited value is set to a maximum value identically by the correction
value, thus deteriorating the image quality output from the LCD. Besides, if setting
the coefficient K to a small value in consideration of this, the gradation data in the
low-gradation range has insufficient variations, thus still causing the problem that
cannot raise the response of the LCD.
In consideration of the problem described above, the present invention is to
set the coefficient K differently based on the gradation data to be displayed on the
LCD. Here, selecting the coefficient K refers to both the present gradation data
being displayed and the gradation data to be displayed newly on the LCD.
In the embodiment of the invention described hereinafter, gradation data for
LCD, i.e., the gradation data being displayed (hereinafter, referred to as previous
gradation data P) and gradation data newly input (hereinafter, referred to as input
gradation data R) are classified into three ranges such as low-gradation data,
middle-gradation data and high-gradation data, as shown in Fig. 3. Of course, the
method of this classification is not limited to a specific example. It is possible to
improve the image quality and the response characteristic of the LCD efficiently
as much as the classification of the gradation data is made in detail. Following Table 1 shows coefficients Ks set according to the previous
gradation data P and the input gradation data R, where the both gradation data
are classified into low-gradation, middle-gradation and high-gradation. Besides,
the gradation data for red R, green G and blue B are formed in the unit of 5-bit,
respectively. If the overall gradation level for one color is 32-level (25), the low-
gradation is set to a range of 0 to 11 levels, the middle-gradation is 12 to 23 levels
and the high-gradation is 24 to 32 levels.
[Table 1]
Figure imgf000013_0001
As shown in Table 1 , in the preferred embodiment,
(1) if the previous gradation data P and the input gradation data R
are all in the low-gradation range, the coefficient is set to "KO";
(2) if the previous gradation data P and the input gradation data R
are all in the middle-gradation range, the coefficient is set to
"K1";
(3) if the previous gradation data P is in the low-gradation range and
the input gradation data R is in the middle-gradation range, or if
the previous gradation data P is in the middle-gradation range
and the input gradation data R is in the low-gradation range, the coefficient is set to "K2"; and
(4) if one of the previous gradation data P and the input gradation
data R is in the high-gradation range, the coefficient is set to "K3".
Meanwhile, the coefficients KO, K1, K2 and K3 should be satisfied with the
condition of following Formula 1:
[Formula 1]
K0>K1>K2>K3
In formula 1 , first, in case that the previous gradation data P and the input
gradation data R are all in the low-gradation range, since the difference value e
between both gradation data obtained in ST 3 of Fig. 2 is not large and, especially,
the variation of the transmitted light amount is weak as shown in Fig. 3, the
coefficient is set to the largest value "KO" in order to make the variation of the
gradation data large.
In case that the previous gradation data P and the input gradation data R
are all in the middle-gradation range, since the difference value e between both
gradation data obtained in ST 3 in Fig. 2 is not large, but slightly larger than in
case that both gradation data are in the low-gradation range, the coefficient is set
to "K1" smaller than "KO".
Meanwhile, in case that the previous gradation data P is in the low-
gradation range and the input gradation data R is in the middle-gradation range,
or in case that the previous gradation data P is in the middle-gradation range and
the input gradation data R is in the low-gradation range, the difference value e between both gradation data obtained in ST 3 in Fig. 2 becomes large, the
coefficient is set to "K2" smaller than "K1".
Besides, in case that one of the previous gradation data P and the input
gradation data R is in the high-gradation range, the coefficient is set to "K3", the
smallest one among the coefficients, in consideration that the value of the
gradation data to be displayed exceeds the maximum value by the gradation data
conversion in ST 5 of Fig. 2.
In applying the method in accordance with the preferred embodiment of the
invention, when the input gradation data R and the previous gradation data P are
input (ST 1 and ST2), the data converting part 32 preferentially sets the coefficient
K based on both gradation data. Here, setting the coefficient K is executed by
using a program or a ROM table.
If the coefficient K is set, the input gradation data is converted by executing
the steps ST3 to ST 9 in Fig. 2.
According to the preferred embodiment as described above in detail, it is
possible to enhance the response characteristic of the LCD maximally by
executing the gradation data conversion gradually according to the level ranges of
the previous gradation data and the input gradation data.
Meanwhile, in the embodiment described above in detail, the data
converting part 32 converts the input gradation data through a predetermined
operation process, however, it can be executed using a separate ROM table
without the operation process. Fig. 4 is a block diagram depicting an apparatus for converting gradation
data in LCD in accordance with another embodiment of the present invention. The
apparatus depicted in Fig. 4 corresponds to the data converting device 30 in Fig.
1, the elements in Fig. 4 substantially identical with those described in Fig. 1 have
the same reference numerals and detailed explanation will be omitted.
In Fig. 4, a ROM table 51 storing plural gradation data to be displayed on
the LCD is established. The ROM table 51 includes first to fourth gradation data
storing parts 511 to 514. Here, the number of gradation data storing part
corresponds to the case that the gradation levels are classified into three ranges
such as low-gradation, middle-gradation and high-gradation and, if the gradation
levels are classified into more detail, the number of the gradation data storing part
increases correspondingly.
The first to fourth gradation data storing parts 511 to 514 store gradation
data to be newly displayed on the LCD against previous gradation data P, i.e., the
gradation data stored in the frame memory 33, and input gradation data R, i.e.,
the gradation data stored in the recording buffer 31. Here, the first gradation data
storing part 511 stores gradation data to be displayed on the LCD against
previous gradation data P and input gradation data R in case that both gradation
data P and R are in the low-gradation range as explained in reference to Table 1.
The second gradation data storing part 512 stores gradation data to be
displayed on the LCD against previous gradation data P and input gradation data
R in case that both gradation data P and R are in the middle-gradation range. The third gradation data storing part 513 stores gradation data to be
displayed on the LCD against previous gradation data P and input gradation data
R in case that the previous gradation data P is in the low-gradation range and the
input gradation data R is in the middle-gradation range, or in case that the
previous gradation data P is in the middle-gradation range and the input gradation
data R is in the low-gradation range.
Besides, the fourth gradation data storing part 514 stores gradation data to
be displayed on the LCD against previous gradation data P and input gradation
data R in case that one of the previous gradation data P and the input gradation
data R is in the high-gradation range.
In the first to fourth gradation data storing parts 511 to 514, the gradation
data calculated by operations are stored in advance, and the values of the
gradation data stored are to be adjusted appropriately based on the response
characteristic of the LCD that the present invention is applied to.
A control part 50 in Fig. 4 corresponds to the data converting part 32 in Fig.
1. However, the control part 50 does not operate based on the previous gradation
data P and the input gradation data R, but reads out appropriate gradation data
from the ROM table 51 based on the previous gradation data P and the input
gradation data R, differently from the data converting part 32. Then, the control
part 50 stores the gradation data read out in a predetermined region of the frame
memory 33.
To wit, if gradation data R is newly input and stored in the recording buffer 32, the control part 50 reads out previous gradation data P, i.e., the gradation data
being displayed on the LCD, from the frame memory 33, corresponding to the
input gradation data R. Here, the operation and configuration for reading out the
corresponding gradation data from the frame memory 33 are substantially
identical with those disclosed in the US Patent Application No. 10/395,663 by the
present inventor and applicant.
Subsequently, the control part 50 reads out appropriate gradation data from
the ROM table 51 based on the input gradation data R stored in the recording
buffer 31 and the corresponding previous gradation data P in the frame memory
33 and stores the gradation data read out in a predetermined region of the frame
memory 33. Here, the configuration and operation of the control part 50 for storing
gradation data to be displayed in predetermined regions of the frame memory 33
are substantially identical with those disclosed in the US Patent Application
10/395,663 by the present inventor and applicant.
As described above, according to the present invention, gradation data to
be newly displayed is generated by converting input gradation data based on
previous gradation data being displayed on the LCD at present. Besides, the
gradation data conversion described above is not executed identically against all
gradation data but based on levels of previous gradation data and input gradation
data.
Accordingly, the present invention can provide a high response of LCD by
executing most optimum gradation data conversion in accordance with the characteristics of the LCD.
Thus far, the embodiments in accordance with the present invention were
described in detail. However, the embodiments described above are just to
explain a desirable example cited in embodying the present invention and the
present invention is not limited to the specified embodiments.
That is, for example, the embodiments described above in detail are an
example cited in applying the present invention to the US Patent Application No.
10/395,663. However, the present invention can be realized also by applying to
the PCT International Application No. PCT/KR2005/000725 disclosed by the
present inventor and applicant in the same manner. The invention disclosed in the
PCT International Application No. PCT/KR2005/000725 has a reading means for
reading out gradation data being displayed on the LCD at present so as to read
out the previous gradation data, being displayed on the LCD at present, directly
from the LCD. Accordingly, if applying the present invention to the PCT
International Application No. PCT/KR2005/000725, the frame memory 33 in Fig. 4
can be omitted.
It will be apparent to those skilled in the art that various modifications and
variations can be made in the method and apparatus for converting gradation data
in LCD of the present invention without departing from the spirit or scope of the
invention. Thus, it is intended that the present invention cover the modifications
and variations of this invention provided they come within the scope of the
appended claims and their equivalents. Industrial Applicability
According to a method and an apparatus for converting gradation data in
LCD of the present invention, gradation data to be newly displayed on the LCD is
generated based on previous gradation data being displayed at present and input
gradation data. Especially, the present invention executes the gradation data
conversion gradually according to gradation levels of previous gradation data and
input gradation data. Accordingly, the prevent invention can raise the response of
the LCD all the more by executing most optimum gradation conversion in
accordance with characteristics of the LCD and, further, removes the after-images
shown on the LCD efficiently.

Claims

1. In a method for converting gradation data, which is applied to
an apparatus for converting gradation data in an LCD having a data converting
device for converting gradation data for driving the LCD and executed by the data
converting device, the method for converting gradation data in LCD comprising
the steps of:
1) receiving input gradation data for driving the LCD;
2) setting a coefficient value for gradation conversion based on the input
gradation data and a level value of previous gradation data that is displayed
previously on the LCD and corresponds to the input gradation data;
3) calculating a difference value between the input gradation data and the
previous gradation data;
4) computing a correction value based on the difference value obtained in
step 3 and the coefficient value set in step 2;
5) generating new gradation data based on the correction value; and
6) fixing the gradation data obtained in step 5 as gradation data for driving
the LCD.
2. The method for converting gradation data in LCD as recited in
claim 1 ,
wherein the coefficient value is set to a larger value in case that the level of
the gradation data is low rather than in case that the level of the gradation data is high.
3. The method for converting gradation data in LCD as recited in
claim 1,
wherein the coefficient value is set to:
KO, if the previous gradation data and the input gradation data are all in
a low-gradation range;
K1 , if the previous gradation data and the input gradation data are all in
a middle-gradation range;
K2, if the previous gradation data is in the low-gradation range and the
input gradation data is in the middle-gradation range, or if the previous
gradation data is in the middle-gradation range and the input gradation
data is in the low-gradation range;
K3, if one of the previous gradation data and the input gradation data is
in a high-gradation range; and
the method satisfies a condition of K0>K1>K2>K3.
4. In an apparatus for converting gradation data to be supplied to an
LCD, the apparatus for converting gradation data in LCD comprising:
a buffer for storing gradation data input from outside;
a frame memory for storing previous gradation data applied to the LCD;
and a data converting means for generating gradation data to be newly
displayed based on the input gradation data and the previous gradation data,
the data converting means generating a correction value by subtracting the
previous gradation data from the corresponding input gradation data and by
multiplying a subtraction result value by a predetermined coefficient value and,
the coefficient value being set according to level ranges of the input
gradation data and the previous gradation data.
5. The apparatus for converting gradation data in LCD as recited in
claim 4,
wherein the coefficient value is set to a larger value in case that the level of
the gradation data is low rather than in case that the level of the gradation data is
high.
6. The apparatus for converting gradation data in LCD as recited in
claim 4,
wherein the coefficient value is set to:
KO, if the previous gradation data and the input gradation data are all in
a low-gradation range;
K1 , if the previous gradation data and the input gradation data are all in
a middle-gradation range;
K2, if the previous gradation data is in the low-gradation range and the input gradation data is in the middle-gradation range, or if the previous gradation data is in the middle-gradation range and the input gradation
data is in the low-gradation range;
K3, if one of the previous gradation data and the input gradation data is
in a high-gradation range; and
the method satisfies a condition of K0>K1>K2>K3.
7. In an apparatus for converting gradation data to be supplied to an
LCD, the apparatus for converting gradation data in LCD comprising:
a buffer for storing gradation data input from outside;
a reading means for reading out previous gradation data from the LCD; and
a data converting means for generating gradation data to be newly
displayed based on the input gradation data and the previous gradation data,
the data converting means generating a correction value by subtracting the
previous gradation data from the corresponding input gradation data and by
multiplying a subtraction result value by a predetermined coefficient value and,
the coefficient value being set according to level ranges of the input
gradation data and the previous gradation data.
8. The apparatus for converting gradation data in LCD as recited in
claim 7,
wherein the coefficient value is set to a larger value in case that the level of the gradation data is low rather than in case that the level of the gradation data is
high.
9. The apparatus for converting gradation data in LCD as recited in
claim 7,
wherein the coefficient value is set to:
KO, if the previous gradation data and the input gradation data are all in
a low-gradation range;
K1 , if the previous gradation data and the input gradation data are all in
a middle-gradation range;
K2, if the previous gradation data is in the low-gradation range and the
input gradation data is in the middle-gradation range, or if the previous
gradation data is in the middle-gradation range and the input gradation
data is in the low-gradation range;
K3, if one of the previous gradation data and the input gradation data is
in a high-gradation range; and
the method satisfies a condition of K0>K1>K2>K3.
10. In an apparatus for converting gradation data to be supplied to an
LCD, the apparatus for converting gradation data in LCD comprising:
a buffer for storing gradation data input from outside;
a frame memory for storing previous gradation data applied to the LCD; a gradation data storing means including the previous gradation data and
gradation data corresponding to the input gradation data; and
a control means for reading out predetermined gradation data from the
gradation data storing means based on the input gradation data and the previous
gradation data and storing the gradation data read out in the frame memory,
the gradation data storing means storing the gradation data obtained by
multiplying a difference value between the input gradation data and the previous
gradation data by a predetermined coefficient value and adding a multiplication
result value to the previous gradation data, and
the coefficient value being set according to level ranges of the input
gradation data and the previous gradation data.
11. The apparatus for converting gradation data in LCD as recited in
claim 10,
wherein the coefficient value is set to:
KO1 if the previous gradation data and the input gradation data are all in
a low-gradation range;
K1, if the previous gradation data and the input gradation data are all in
a middle-gradation range;
K2, if the previous gradation data is in the low-gradation range and the
input gradation data is in the middle-gradation range, or if the previous
gradation data is in the middle-gradation range and the input gradation data is in the low-gradation range;
K3, if one of the previous gradation data and the input gradation data is
in a high-gradation range; and
the method satisfies a condition of K0>K1>K2>K3.
12. In an apparatus for converting gradation data to be supplied to an
LCD, the apparatus for converting gradation data in LCD comprising:
a buffer for storing gradation data input from outside;
a reading means for reading out previous gradation data from the LCD;
a gradation data storing means including the previous gradation data and
gradation data corresponding to the input gradation data; and
a control means for reading out predetermined gradation data from the
gradation data storing means based on the input gradation data and the previous
gradation data and storing the gradation data read out in the frame memory,
the gradation data storing means storing the gradation data obtained by
multiplying a difference value between the input gradation data and the previous
gradation data by a predetermined coefficient value and adding a multiplication
result value to the previous gradation data, and
the coefficient value being set according to level ranges of the input
gradation data and the previous gradation data.
PCT/KR2005/002315 2005-07-19 2005-07-19 Method and apparatus for converting gradation data in lcd WO2007011086A1 (en)

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US9326877B2 (en) 2006-09-29 2016-05-03 Apollo Endosurgery, Inc. Apparatus and method for intragastric balloon with in situ adjustment means
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