IP Library Granted Patent US 6,924,778
Granted Patent B2
US 6,924,778 · App. 09/989,117 · Granted Aug 2, 2005

Method and device for implementing subframe display to reduce the pseudo contour in plasma display panels

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Quick Facts
Patent No.
US 6,924,778
App. No.
09/989,117
Granted
Aug 2, 2005
Kind
B2
Abstract

A method for driving a plasma display panel is provided in which dynamic pseudo contours are reduced and pattern noises are suppressed so that image quality of an animation display is improved. In the method, a superposition method is applied only to the area of a display image, which is made of pixels having a gradation at which only one of plural subframes having the same luminance weight concerning the superposition method is lighted and has a luminance gradient within a preset value range between the neighboring pixels.

Claims (24)

1. A method for driving a plasma display panel by replacing a frame with a plurality of subframes having weights of luminance and by setting light emission of cells on and off for each subframe so as to realize a gradation display, the method comprising:

assigning a luminance weight to each of the subframes so that plural subframe expressions, as combinations of subframes to be lighted, are prepared for a specific gradation; and

applying a superposition method in which the plural subframe expressions are mixed only to the specific area that is included in the frame, is made of pixels having the specific gradation and has a luminance gradient within a preset value range between the neighboring pixels.

2. The method according to claim 1 , wherein the specific area is an area larger than a predetermined value.

3. A method for driving a plasma display panel by replacing a frame with a plurality of subframes having weights of luminance and by setting light emission of cells on and off for each subframe so as to realize a gradation display, the method comprising:

assigning a luminance weight to each of the subframes so that plural subframe expressions, as combinations of subframes to be lighted, are prepared for a specific gradation; and

applying a superposition method in which the plural subframe expressions are mixed only to the specific area that is included in the frame, made of pixels having the specific gradation and has a luminance gradient within a preset value range between the neighboring pixels and is a portion of a moving object different from a previous frame.

4. The method according to claim 3 , wherein the specific area is an area larger than a predetermined value.

5. A device for driving a plasma display panel by replacing a frame with a plurality of subframes and by setting light emission of cells on and off for each subframe so as to realize a gradation display, wherein:

the device comprises an area decision circuit dividing the frame into a specific area that is made of pixels having a specific gradation and a luminance gradient within a preset value range between neighboring pixels and other areas, and

the device performs a light emission control for the specific area of the frame by applying a superposition method in which plural subframe expressions are mixed while performing another light emission control for other areas without applying the superposition method.

6. A device for driving a plasma display panel by replacing a frame with a plurality of subframes and by setting light emission of cells on and off for each subframe so as to realize a gradation display, wherein:

the device comprises an area decision circuit dividing the frame into a specific area that is made of pixels having a specific gradation and a luminance gradient within a preset value range between the neighboring pixels and is a portion of a moving object, different from a previous frame and other areas, and

the device performs a light emission control for the specific area of the frame by applying a superposition method in which plural subframe expressions are mixed while performing another light emission control for other areas without applying the superposition method.

7. A display device, comprising:

an AC type plasma display panel; and

a driving device driving the plasma display panel and comprising:

an area decision circuit dividing the frame into a specific area that is made of pixels having a specific gradation and a luminance gradient within a preset value range between neighboring pixels and other areas, and

the driving device performs a light emission control for the specific area of the frame by applying a superposition method in which plural subframe expressions are mixed while performing another light emission control for other areas without applying the superposition method.

8. A display device, comprising:

an AC type plasma display panel; and

a driving device driving the plasma display panel and comprising:

an area decision circuit dividing the frame into a specific area that is made of pixels having a specific gradation and luminance gradient within a preset value range between neighboring pixels and is a portion of a moving object different from a previous frame and other areas, and

the driving device performs a light emission control for the specific area of the frame by applying a superposition method in which plural types of subframe expressions are mixed while performing another light emission control for other areas without applying the superposition method.

Assignments (4)
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Oct 29, 2008
From: HITACHI LTD.
To: HITACHI PLASMA PATENT LICENSING CO., LTD.
Reel/Frame 021785/0512 →
TRUST AGREEMENT REGARDING PATENT RIGHTS, ETC. DATED JULY 27, 2005 AND MEMORANDUM OF UNDERSTANDING REGARDING TRUST DATED MARCH 28, 2007 Recorded Apr 13, 2007
From: HITACHI LTD.
To: HITACHI PLASMA PATENT LICENSING CO., LTD.
Reel/Frame 019147/0847 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Dec 23, 2005
From: FUJITSU LIMITED
To: HITACHI, LTD.
Reel/Frame 017105/0910 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Nov 21, 2001
From: AWAMOTO, KENJI; TAKAYAMA, KUNIO
To: FUJITSU LIMITED
Reel/Frame 012318/0572 →