Method and a circuit for gradationally driving a flat display device

• US 6,630,916 B1
• Filed: 12/03/1999
• Issued: 10/07/2003
• Est. Priority Date: 11/28/1990
• Status: Expired due to Fees

• Current Assignee: Hitachi Plasma Patent Licensing Company Limited (Hitachi, Ltd.)
• Original Assignee: Fujitsu Limited
• Inventors: Shinoda, Tsutae
• Primary Examiner(s): CHOW, DOON Y
• Application Number:
  US09/451,351
• Time in Patent Office: 1,404 Days
• Field of Search: 345/60, 345/63, 345/68, 345/61, 345/66, 345/103, 313/584, 313/585, 313/586, 313/484, 313/485, 315/169.1, 315/169.5
• US Class Current: 345/60
• CPC Class Codes: G09G 2310/0216 Interleaved control phases for different scan lines in the same sub-field, e.g. initialization, addressing and sustaining in plasma displays that are not simultaneous for all scan lines
• CPC Class Codes: G09G 3/2003 Display of colours specific for liquid crystal displays G09G3/3607
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/2025 the sub-frames having all the same time duration
• CPC Class Codes: G09G 3/2927 Details of initialising
• CPC Class Codes: G09G 3/2935 Addressed by erasing selected cells that are in an ON state
• CPC Class Codes: G09G 3/294 for lighting or sustain discharge
• CPC Class Codes: G09G 3/2946 by introducing variations of the frequency of sustain pulses within a frame or non-proportional variations of the number of sustain pulses in each subfield
• CPC Class Codes: G09G 3/297 using opposed discharge type panels
• CPC Class Codes: G09G 3/298 using surface discharge panels
• CPC Class Codes: H01J 11/10 AC-PDPs with at least one main electrode being out of contact with the plasma
• CPC Class Codes: H01J 11/12 with main electrodes provided on both sides of the discharge space
• CPC Class Codes: H01J 11/36 Spacers, barriers, ribs, partitions or the like
• CPC Class Codes: H01J 11/42 Fluorescent layers

Abstract

A method and circuit of driving a flat display panel formed of a plurality of cells each having a memory function, wherein the cells are formed at cross points of a plurality of X-electrodes and a plurality of Y-electrodes orthogonal to the X-electrodes and a period of a frame for displaying a single picture is divided into a plurality of sequential subframes. Each of the subframes comprises an addressing period, during which cells to be lit later in a display period are selected from all the cells by being written so as to have a wall charge therein, and a display period, subsequent to the address period, for lighting the selected cells by applying sustain pulses to all the cells. A number of sustain pulses included in each display period is predetermined differently for each subframe, according to a weight given to each subframe. Gradation of visual brightness of each cell is determined by the accumulated number of the sustain pulses included in the subframes that are selectively operated during a single frame according to a required brightness level for each cell. An adequate time accumulation is thereby allocated to a required number of subframes to achieve a quality brightness-gradation for each cell.

Claims

1. A method for driving a flat display panel with a gradation of visual brightness, the display panel having a plurality of pixels arranged in plural lines, each line having plural pixels and each pixel having a memory function, the method comprising:

dividing, with time, each frame to be displayed on said display panel into a respective plurality of successive subframes, the subframes having respective, predetermined weights of brightness gradations and being individually selected to determine the brightness gradation of the respective frame, each subframe being applied at a common timing with respect to all of the plural lines of the display panel;

further dividing, with time, each of the subframes into respective, first and second successive time periods, each time period having a respective, common timing with respect to all of the plural lines forming the display panel;

controlling respective timings of a start of the first time period and of an end of the second time period of each subframe to be in common for all of the plural lines forming the display panel;

setting the time duration of the second time period of each subframe in correspondence to the respective weight of the brightness gradation of that subframe;

in the first time period of each subframe, writing display data in corresponding pixels of the display panel by selectively forming a memory medium in each of the corresponding pixels;

in the second time period of each subframe, concurrently producing a display in each corresponding pixel in which a respective memory medium was formed in the first time period, for the respective time duration of the second time period of the subframe; and

repeating the operations of the subframe with the first time period and the second time period so as to display a picture with gradation.

2. A method for driving a flat display panel with a gradation of visual brightness, the display panel having a plurality of pixels arranged in plural lines, each line having plural pixels and each pixel having a memory function, the method comprising:

dividing, with time, each frame to be displayed on said display panel into a respective plurality of successive subframes, the subframes having respective, predetermined weights of brightness gradations and being individually selected to determine the brightness gradation of the respective frame, each subframe being applied at a common timing with respect to all of the plural lines of the display panel;

further dividing, with time, each of the subframes into respective, first and second successive time periods, each time period having a respective, common timing with respect to all of the plural lines forming the display panel;

controlling respective timings of a start of the first time period and of an end of the second time period of each subframe to be in common for all of the plural lines forming the display panel;

setting the time duration of the second time period of each subframe in correspondence to the respective weight of the visual brightness gradation of that subframe;

in the first time period, and at a common timing for each line of pixels and in succession for the plural lines, selectively forming a memory medium in each selected pixel of the plurality of pixels of said display panel using a first pulse train of a first pulse pitch;

in said second time period of each subframe, concurrently producing a display at each selected pixel, in which a memory medium was formed, for the time duration of the second time period of the respective subframe and in succession for the plural subframes of each frame using a second pulse train having a second pulse pitch, a respective number of pulses of the second pulse train being supplied for display in the second time period in accordance with the predetermined weights of the brightness gradations thereof; and

repeating the operations of the subframe with the first time period and the second time period so as to display a picture with gradation.

3. A method of driving a matrix display panel as claimed in claim 2, wherein the first and second pulse pitches are of different values.

4. A method of driving a matrix display panel as claimed in claim 3, wherein the second pulse train has a common pulse pitch in each of the plurality of successive subframes of a frame.

5. A method of driving a matrix display panel as claimed in claim 2, wherein the respective, second time periods of the plurality of successive subframes are of a common duration and, for the plurality of successive subframes, the respective second pitches of the respective second pulse train are of respective, different values in accordance with the predeternined, different weights of the respective visual brightness gradations of the successive subframes.

6. A method of driving a matrix display panel having a plurality of cells arranged in a plurality of lines, each of the cells having a memory function, the method comprising:

dividing a period of a display frame of plural lines into a plurality of successive subframes, each subframe having an addressing period during which cells to be lit later in a display period are selected from all of the cells so as to have a wall charge therein, and a display period subsequent to the addressing period for lighting the selected cells by concurrently applying sustain pulses to all of the cells, each display period being independent of the addressing period for the all lines, the respective numbers of sustain pulses applied in the plurality of successive subframes depending on predetermined weights of brightness gradations of the plurality of successive subframes.

7. A method of driving a matrix display panel as recited in claim 6, wherein the respective numbers of sustain pulses applied in the displaying periods of the plurality of successive subframes are chosen so that the visual brightness gradations meet desired gamma characteristics.

8. A method of driving a matrix display panel having a plurality of pixels arranged in a plurality of lines, each of said pixels having a memory function, said method comprising:

dividing a period of a display frame into a plurality of subframes, wherein the plurality of lines are concurrently activated in each subframe, each subframe including respective and successive addressing and displaying periods;

in each addressing period, addressing a pixel by selectively forming a memory medium, according to said memory function, in a selected pixel of a selected line, sequentially for the plurality of lines, and, in the respective, successive displaying periods, lighting each addressed pixel by concurrently applying sustain pulses to all the pixels, the plurality of successive subframes being allocated respective, predetermined numbers of the sustain pulses in accordance with respective, predetermined weights of visual brightness gradations thereof; and

an order of the respective subframes of a frame being selected arbitrarily in advance of producing a display in accordance with display conditions.

9. A method of driving a plasma display panel having a plurality of parallel first electrodes, a plurality of second electrodes each of which is disposed between adjacent ones of said first electrodes and a plurality of third electrodes in parallel with each other in a crossing direction relative to said first and second electrodes, a plurality of first cells being formed substantially at respective first positions defined by crossed points of the first electrodes and said third electrodes and a plurality of second cells being formed between the first electrodes and the second electrodes at respective second positions corresponding to the first positions of the first cells, wherein the first cells are selectively addressed corresponding to a picture to be displayed and said second cells display the picture corresponding to the selected ones of the first cells, the method comprising:

dividing a period of a display frame into a plurality of subframes, each subframe including respective and successive addressing and displaying periods, each said displaying period being independent of the addressing period with respect to all of the first and second cells;

in each addressing period, addressing said first cells by selectively forming a wall charge in a selected one of said first cells on each sequentially selected one of said first electrodes, and, in the respective, successive displaying period, lighting said second cells corresponding to selected ones of said first cells by concurrently applying sustain pulses to all the second cells, the plurality of successive subframes being allocated respective, predetermined numbers of the sustain pulses in accordance with respective, predetermined weights of visual brightness gradations thereof; and

an order of each one of said subframes is arbitrarily chosen in advance corresponding to a displaying condition.

10. A method as recited in claim 9, wherein the addressing further comprises:

applying a pulse concurrently between plural first electrodes and plural second electrodes while keeping plural third electrodes at a predetermined voltage, before the first cells are selectively addressed, so that respective wall charges are generated in each of the first and second cells.

11. A method of driving a matrix display panel, formed of a plurality of cells arranged in a plurality of lines, each cell being capable of having a charge accumulated therein, the method comprising:

dividing a period of a frame displaying a single picture into a plurality of successive subframes, each subframe including an addressing period and a displaying period which is independent of said addressing period with respect to all of the lines;

in each addressing period, performing an addressing operation by erasing the charge accumulated in each unselected cell of a selected line, in sequence for the plurality of lines and, in the related displaying period, the selected cells being lit by concurrently applying sustain pulses to all of the plurality of cells, wherein each subframe of the plurality of successive subframes is allocated a predetermined number of sustain pulses in accordance with respective, predetermined brightness gradations of the plurality of successive subframes, a gradation of brightness of a selected cell in a given frame being determined by the total number of sustain pulses applied to the cell in the respective subframes of the given frame.

12. A method of driving a matrix display panel, formed of a plurality of pixels each having a memory function, comprising:

dividing with time a period of a frame displaying a single picture into a plurality of subframes, each subframe comprising;

an address period, executed during a common time for all the pixels, to address a pixel by selectively forming a memory medium in a selected pixel of al the pixels, and

a display period, independent from said address period, to light said addressed pixel by an application of sustain pulses to all the pixels, each display period of the respective subframe being allocated a predetermined number of said sustain pulses, said allocated number being different for each subframe so as to weight a gradation to said respective subframe,

whereby a gradation of visual brightness of said lit pixel is determined by selectively performing the address operation in each address period of said divided subframe for each of said pixels for each frame.