Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2002-03-29
2004-08-10
Shalwala, Bipin (Department: 2673)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S037000, C345S041000, C345S072000, C345S083000, C345S088000, C345S589000, C345S591000, C345S600000, C345S601000, C345S602000, C345S605000, C445S024000
Reexamination Certificate
active
06774875
ABSTRACT:
This application incorporates by reference of Taiwan application Ser. No. 090108205, filed on Apr. 4, 2001.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates in general to a method for compensating luminance, and more particularly to a method for compensating luminance, and the method is suitable for use in a plasma display panel.
2. Description of Related Art
With the rapid development of the fabrication technology of the audio/video (A/V) device, it can be foreseen that people in the future will enjoy the audio and video service with much higher performance than now. Taking the displaying device as an example, the conventional cathode ray tube (CRT) displaying device has not only the disadvantages of large volume and the serious radiation issue, but also that the image at the brim region of the screen has very serious image contortion and distortion problem. Therefore, the conventional CRT displaying device certainly cannot satisfy the people who desire to enjoy the audio and video service with higher performance. When the high definition digital television (HDTV) system starts to operate and broadcast in the near future, the conventional CRT displaying device designed with the analog manner will be gradually thrown away. Instead, the plasma display panel (PDP), which has at least advantages of low radiation, low power consumption, and large displaying area but small volume, can be a very promising product to replace the CRT displaying device.
Referring to
FIG. 1
, it is a drawing, schematically illustrating a loading effect on a plasma display panel. The loading effect is a phenomenon that the luminance of a pixel is affected by the luminance of the other pixels which are in the same row with the pixel. The loading effect causes a difference between the actual luminance and the expected luminance of the pixel and the actual luminance is less than the expected luminance. As shown in
FIG. 1
, the panel includes three pixel rows
102
,
104
, and
105
. The pixel row
102
includes pixel sub-rows
106
and
110
, the pixel row
104
includes pixel sub-rows
108
and
112
, and the pixel row
105
includes pixel sub-rows
109
and
113
. The luminance of the pixel sub-row
106
is less than the pixel sub-row
108
and the luminance of the pixel sub-row
108
is less than the luminance of the pixel sub-row
109
. In addition, each pixel of the sub-rows
110
,
112
, and
113
has the same pixel signal. Each pixel signal includes a luminance value to determine the luminance of the pixel. In theory, the luminance of pixel sub-rows
110
,
112
, and
113
should be the same. However, in practical, the pixel sub-rows
110
,
112
, and
113
have the individual luminance L
110
, L
112
, and L
113
, respectively. The relation among L
110
, L
112
, and L
113
is L
110
>L
112
>L
113
. And the luminance of pixel sub-rows
110
,
112
, and
113
are all less than the expected luminance which is corresponded to the luminance value of the pixel signals. In other words, the luminance of the pixel is affected by the luminance of the other pixels in the same row which causes the actual luminance is less than the expected luminance of the pixel. If the luminance of the other pixels in the same row is larger, the difference between the actual luminance and the expected luminance of the pixel will be larger. This phenomenon is called the loading effect.
A frame data is composed of a number of pixel signal rows. A plasma display panel with a resolution of 800×600 is taken as an example, in which it means that the whole panel has 800 pixels for each row, and 600 pixels for each column. The frame data should include 600 pixel signal rows. Each pixel signal row has 800 pixel signals. Each pixel signal includes a luminance value. The luminance value of the pixel signal is represented by a eight-bit binary number. The range of the luminance value is from (00000000)
2
to (11111111)
2
represented by binary numbers or from 0 to 255 represented by decimal numbers. The larger the luminance value of the pixel signal is, the larger the luminance of the pixel which receives the pixel signal will be. The smallest value 0 corresponds to the full black luminance of the pixel and the largest value 255 corresponds to the full white luminance of the pixel respectively.
Referring to
FIG. 2
, it is a block diagram, schematically illustrating a conventional device for compensating luminance
200
. The conventional device for compensating luminance
200
includes a field programmable gate array (FPGA)
202
and two memory devices
204
which are coupled to the FPGA
202
respectively. The conventional device for compensating luminance
200
can determine whether or not the luminance compensation is necessary to be performed. If performing luminance compensation is determined to be necessary, the device for compensating luminance
200
will perform luminance compensation on the pixel signal row.
Referring to
FIG. 3
, it is a flow chart, schematically illustrating the conventional luminance compensation method performed by the device for compensating luminance. The conventional method for compensating luminance of the plasma display panel is described in the following. First, in the step
302
, the device for compensating luminance will sequentially read each pixel signal of the pixel signal row.
Then, in the following step
304
, the device for compensating luminance computes the load of the pixel signal row. According to forgoing descriptions, if the luminance of the other pixels in the same row is larger, the actual luminance of the pixel will be less and the difference between the actual luminance and the expected luminance will be larger. Therefore, the degree of the loading effect is determined by the luminance of the pixel row. When the device for compensating luminance determines whether or not luminance compensation is necessary to be performed, the magnitude of the luminance value of each pixel signal in the pixel signal row is a factor for consideration. In the conventional method for compensating luminance, the load of the pixel signal row is defined as the number of pixel signals in the pixel signal row that the luminance value of the pixel signals is larger than the predetermined threshold luminance value. The magnitude of the load of the pixel signal row determines the degree of the loading effect of the pixel row in the plasma display panel. The device for compensating luminance computes the load of the pixel signal row by comparing luminance value of each pixel signal to the threshold luminance value. According to the forgoing descriptions, each luminance value is represented by a binary number of eight bits. The higher bit has more influence than the lower bit of the luminance value on the determination of the luminance of the pixel. Therefore, when comparing luminance value of each pixel signal with the threshold luminance value, only the highest-three-bit of the pixel signal is needed to be put into consideration. The highest-three-bit of the threshold luminance value is defined to be 101 in conventional luminance compensation method. If the highest-three-bit of the luminance value is larger than or equal to 101, the luminance value of this pixel signal is considered as the one to increase the degree of the loading effect. On the contrary, if the highest-three-bit of the luminance value is less than 101, the luminance value of this pixel signal is considered as the one not to increase the degree of the loading effect. The load of the pixel signal row is the number of the pixel signal in the pixel signal row that the luminance value of the pixel signals is larger than or equal to (10100000)
2
.
Then, in the following step
306
. If the load of the pixel signal row is larger than or equal to the predetermined threshold load, luminance compensation will be performed. If the load of the pixel signal row is less than the threshold load, luminance compensation will not be performed and the pixel signal row will be outputted directly form the device for compensati
Huang Jih-Fon
Tong Shu-Rong
Tsai Tu-Hao
AU Optronics Corp.
Kovalick Vincent E.
Rabin & Berdo P.C.
Shalwala Bipin
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