Device and method for varying the row scanning time to compensate the signal attenuation depending on the distance between pixel rows and column driver

• US 20040239604A1
• Filed: 04/02/2004
• Published: 12/02/2004
• Est. Priority Date: 10/03/2001
• Status: Active Grant

• Current Assignee: TPO Hong Kong Holding Limited (InnoLux Corporation)
• Original Assignee: TPO Hong Kong Holding Limited (InnoLux Corporation)
• Inventors: Watsuda, Hirofumi
• Granted Patent: US 7,233,323 B2
• Time in Patent Office: Days
• US Class Current: 345/95
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2320/0223 Compensation for problems related to R-C delay and attenuation in electrodes of matrix panels, e.g. in gate electrodes or on-substrate video signal electrodes
• CPC Class Codes: G09G 3/20 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
• CPC Class Codes: G09G 3/3677 suitable for active matrices only

Abstract

A display device comprises a control circuit (50) for changing a time period of applying a signal voltage to each of the signal lines (42-1 to 42-n) and a scanning voltage to each of the scanning lines (41-1 to 41-m) within one vertical scanning period (T). The control circuit (50) controls each of horizontal scanning periods (t₁ to t_m) in such a manner that the period is gradually increased from the scanning line (41-m) located close to a vertical driving circuit (30) to the scanning line (41-1) located remote from the vertical driving circuit (30). In this way, when writing a signal voltage to a pixel via the signal lines, at each pixel the target potential is reached within the time period of applying the signal voltage.

Claims

1. A display device comprising:

a matrix of rows and columns of pixels;

a group of first wires, each first wire coupled to a respective one of the rows of pixels;

a group of second wires, each second wire coupled to a respective one of the columns of pixels;

first voltage applying means for applying a scanning voltage to each of the first wires successively; and

second voltage applying means for applying respective signal voltages to each of the second wires in synchronization with the scanning voltage successively applied to the first wires, characterized in that the display device further comprises a period changing means for changing a time period of applying the signal voltage in dependence on a distance between a row of pixels and the second voltage applying means.

2. A display device as claimed in claim 1, characterized in that the period changing means changes a time period of applying the scanning voltage to each of the first wires in synchronization with the time period of applying the signal voltage to each of the second wires.

3. A display device as claimed in claim 1, characterized in that the period changing means selects the time period of applying the signal voltage to be longer when the signal distance between a row of pixels and the second voltage applying means increases.

4. A display device as claimed in claim 1, characterized in that applying scanning voltages to all the first wires is completed within a predetermined period time.

5. A method of driving a display device comprising a matrix of rows and columns of pixels, a group of wires with each wire coupled to a respective one of the rows of pixels, a group of second wires with each wire coupled to a respective one of the columns of pixels, and a driver stage for driving the group of second wires, the method comprising the steps of:

applying successively a scanning voltage to each of the first wires; and

applying signal voltages to each of the second wires in synchronization with the scanning voltage applied to the first wires, characterized in that time period of applying the scanning signal is changed in dependence on a distance between a row of pixels to which the scanning signal is applied and the driver stage.