Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2001-10-31
2004-12-07
Liang, Regina (Department: 2674)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S089000, C345S096000, C345S209000
Reexamination Certificate
active
06828953
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a method of driving a simple matrix type liquid crystal display panel using STN liquid crystals or the like and, more particularly, to a method of driving a liquid crystal display panel of low power consumption suitable for intermediate tone display by frame modulation.
2. Description of the Related Art
A simple matrix type liquid crystal panel is constructed by maintaining a liquid crystal layer between a row electrode group and a column electrode group to define a plurality of pixels in matrix form. Further, as methods for driving the simple matrix type liquid crystal display panel, there are the voltage averaging method, the SA method and the MLA method.
The voltage averaging method is a method of driving a simple matrix type liquid crystal display panel for successively selecting respective row electrodes one by one and providing all the column electrodes with data signals in correspondence with ON/OFF states in accordance with selected timings. Therefore, the voltage applied to respective electrodes becomes high only once in one frame cycle T for selecting all the row electrodes and becomes a constant bias voltage during a remaining nonselection time period. According to the voltage averaging method, when the response speed of the liquid crystal material used is slow, there is provided a change in brightness in accordance with the effective value of the waveform of the applied voltage in the one frame cycle to thereby maintain the most suitable contrast for the conditions. However, when the division number is increased and frame frequency is reduced, the difference between frame cycle time and response time of liquid crystal is reduced, the liquid crystal responds separately to each applied pulse, a flicker in brightness referred to as a frame response phenomenon becomes apparent, and the contrast is reduced.
The SA (Smart Addressing) method is another method for driving a simple matrix type liquid crystal display panel. In either the voltage averaging method or the SA method, the respective row electrodes are successively selected one at a time and data signals in correspondence with ON/OFF states are provided to all the column electrodes in conformity with selected timings. However, common nonselection levels of contiguous frames are different from each other in the former and the same in the latter.
The MLA method is also referred to as the multiple line addressing or multiple line selecting method for simultaneously selecting a plurality of row electrodes so that apparent high frequency formation is achieved and the frame response phenomenon which is problematic in the voltage averaging method is restrained. A unique scheme is adopted in the MLA method in order to simultaneously select a plurality of row electrodes and display respective pixels independently from each other. In this scheme there is carried out set successive scanning involving applying a plurality of row signals represented by a set of orthogonal functions to a row electrode group according to a set order for each respective selection time, there is successively carried out a cross-products operation between the set of orthogonal functions and a set of selected pixel data, and column signals having voltage levels in accordance with the result of the cross-products operation are applied to a column electrode group during the selection time in synchronism with the successive scanning of the set.
Further, the MLA method is disclosed in Japanese Patent Laid Open No. 100642/1993, Japanese Patent Laid-Open No. 27907/1994, Japanese Patent Laid-Open No. 72454/1995, Japanese Patent Laid-Open No. 193679/1995, Japanese Patent Laid-Open No. 199863/1995, Japanese Patent Laid-Open No. 311564/1995, Japanese Patent Laid-Open No. 184807/1996, Japanese Patent Laid-Open No. 184808/1996, Japanese Patent Laid-Open No. 2000-19482 and so on.
Next, as multiple gradation display methods of a simple matrix type liquid crystal display panel, there are generally provided a pulse width modulating system and a frame modulating system, with the latter established as an inexpensive, technologically sound method. The frame modulating system is a system in which two gradations of ON/OFF are selectively chosen over a plurality of frames to thereby provide two or more gradations utilizing temporal average values. Further, the intermediate tone display of the simple matrix type liquid crystal display panel is realized by a combination of the driving method and the multiple gradation display method.
Here, an investigation will be given of power consumption of a simple matrix type liquid crystal display panel with the frame modulating system as the multiple gradation display method, comparing when the panel is driven respectively by the voltage averaging method, the SA method and the MLA method. Further, the frame modulation is carried out by either one row at a time or one pixel at a time.
FIG. 2
shows an example of a 5 gradation frame modulation pattern applied to a simple matrix type liquid crystal display panel. In
FIG. 2
, at gradation level 0, all values of intersections of rows and columns of the simple matrix type liquid crystal display panel are represented by 0 (OFF) from the 1-st frame to the 4-th frame. Here, the simple matrix type liquid crystal display panel is provided with a matrix of N rows×M columns.
At gradation level 1, 1 (ON) is given to pixels at intersections of (2n+1)-th row and odd number columns of the 1st frame, intersections of (2n+1)-th row and even number columns of the 2nd frame, intersections of (2n+2)-th row and odd number columns of the 3rd frame and intersections of (2n+2)-th row and even number columns of the 4th frame and 0 (OFF) is given to other pixels in the simple matrix type liquid crystal display panel. Here, notation n designates an integer of 0 through N/2. Therefore, notation (2n+1) throw represents an odd number row and notation (2n+2)-th row represents an even number row contiguous thereto.
At gradation level 2, 1 (ON) is given to pixels at intersections of the (2n+1)-th row and odd number rows of the 1st frame, intersections of the (2n+2)-th row and even number columns of the 1st frame, intersections of the (2n+1)-th row and even number columns of the 2nd frame, intersections of the (2n+1)-th row and odd number columns of the 3rd frame, intersections of (2n+2)-th row and even number columns of the 3rd frame, intersections of the (2n+1)-th row and odd number columns of the 4th frame and intersections of the (2n+2)-th row and even number columns of 4-th frame, and 0 (OFF) is given to other pixels of the simple matrix type liquid crystal display panel.
At gradation level 3, 0 (OFF) is given to pixels at intersections of the (2n+1)-th row and odd number columns of the 1st frame, intersections of the (2n+1)-throw and even number columns of the 2nd frame, intersections of the (2n+2)-th row and odd number columns of the 3rd frame and intersections of the (2n+2)-th row and even number columns of the 4th frame, and 1 (ON) is given to other pixels in the simple matrix type liquid crystal display panel.
At gradation level 4, 1 (ON) is given to all of the pixels at intersections of rows and columns of the simple matrix type liquid crystal display panel from 1-th frame to 4-th frame.
First,
FIGS. 5A and 5B
show column electrode waveforms when multiple gradation display is carried out by applying the frame modulating system based on the 5 gradation frame modulation pattern of
FIG. 2
to the simple matrix type liquid crystal display panel driven by the voltage averaging method or the SA method and when scanning is carried out from an upper portion to a lower portion of a screen. However, for simplifying the explanation, display data is data of one color of intermediate tone.
That is,
FIG. 5A
shows a column electrode waveform when the pixels of the intersections of a certain column's electrodes with those of t
Adams & Wilks
Dinh Duc Q
Liang Regina
Seiko Instruments Inc.
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