Display apparatus and display driving method for effectively eliminating the occurrence of a moving image false contour

• US 7,420,576 B2
• Filed: 03/24/2004
• Issued: 09/02/2008
• Est. Priority Date: 06/30/2003
• Status: Expired due to Fees

• Current Assignee: Fujitsu Hitachi Plasma Display Limited (Hitachi, Ltd.)
• Original Assignee: Fujitsu Hitachi Plasma Display Limited (Hitachi, Ltd.)
• Inventors: Takeuchi, Masanori, Yamamoto, Akira, Ohta, Shunji, Tajima, Masaya, Chiaki, Yutaka
• Primary Examiner(s): DHARIA, PRABODH M
• Application Number:
  US10/807,252
• Publication Number:
  US 20040263541A1
• Time in Patent Office: 1,623 Days
• Field of Search: 345 60- 69, 345/690, 345/204, 345/589, 345/59, 345/692, 345/87, 345/89, 345/72, 345/596, 345/600, 345/473, 345/82, 345/76, 345/94, 345/208, 345/211, 315/169.4, 359/618, 359/501, 359/507, 359/527, 313/483, 313/586, 701/211, 348/346, 235/462.42, 235/462.11, 235/462.07, 600/173, 600/544, 382/275, 382/166, 710/13
• US Class Current: 345/691
• CPC Class Codes: G09G 2320/0261 in the context of movement of objects on the screen or movement of the observer relative to the screen
• CPC Class Codes: G09G 2320/0266 Reduction of sub-frame artefacts
• CPC Class Codes: G09G 2320/0271 Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping
• CPC Class Codes: G09G 2320/103 Detection of image changes, e.g. determination of an index representative of the image change
• CPC Class Codes: G09G 2320/106 Determination of movement vectors or equivalent parameters within the image
• CPC Class Codes: G09G 2340/0428 Gradation resolution change
• CPC Class Codes: G09G 3/2029 the sub-frames having non-binary weights
• CPC Class Codes: G09G 3/2059 using error diffusion
• CPC Class Codes: G09G 3/2077 by a combination of two or more gradation control methods
• CPC Class Codes: G09G 3/2803 Display of gradations G09G3/288 takes precedence

Abstract

A display apparatus displaying gray scale by using a subfield method has a gain control circuit, a sub gain control circuit, and an error diffusion circuit. The gain control circuit has the number of gray scale levels of an input signal and outputting a first intermediate image signal with a first number of gray scale levels, and the sub gain control circuit receives the first intermediate image signal, compresses the number of gray scale levels of the first intermediate image signal, and outputs a second intermediate image signal with a second number of gray scale levels. The error diffusion circuit receives the second intermediate image signal and increase the number of gray scale levels by simulating additional gray scale levels through error diffusion.

Claims

1. A display apparatus that expresses luminance by varying light emission time length and displays gray scale by using a subfield method, comprising:

a main path outputting first display data having a number of gray scale levels N;

a sub path outputting second display data having a number of gray scale levels M, where M is less than N; and

a switch circuit selecting and outputting either one of inputted said first data display data and said second display data in a unit of a pixel according to a result of a detected amount of motion,

wherein the main path comprises a first gain control circuit reducing the number of gray scale levels, a second gain control circuit further reducing the number of gray scale levels from said first gain control circuit, and an error diffusion circuit performing error diffusion on an output signal of said second gain control circuit.

2. The display apparatus according to claim 1, wherein

a fractional part of the output signal from said first gain control circuit is applied to said error diffusion circuit, as is, via said second gain control circuit, and

said error diffusion circuit performs error diffusion based on the fractional part which is output from both of said first gain control circuit said second gain control circuit.

3. The display apparatus according to claim 2, wherein

an output signal of an integer part from said second gain control circuit is output, so that same data is successively outputted with respect to said input signal with predetermined gray scale levels, which is different only by 1 when setting for light emission of an input signal to display in ascendant order.

4. The display apparatus according to claim 1, wherein a most heavily weighted subfield is set for light emission along with at least one other subfield.