Display device

• US 8,154,498 B2
• Filed: 10/20/2006
• Issued: 04/10/2012
• Est. Priority Date: 10/20/2005
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Corporation of America (Panasonic Holdings Corporation)
• Original Assignee: Hitachi Displays Limited (Japan Display Incorporated), Panasonic Liquid Crystal Display Company Limited (Panasonic Holdings Corporation)
• Inventors: Katayama, Yukari, Kudo, Yasuyuki, Mamba, Norio, Matsudo, Toshimitsu
• Primary Examiner(s): Awad, Amr
• Assistant Examiner(s): WILLIS, RANDAL L
• Application Number:
  US11/583,880
• Publication Number:
  US 20070091050A1
• Time in Patent Office: 1,999 Days
• Field of Search: 345 98-100
• US Class Current: 345/100
• CPC Class Codes: G09G 2310/0275 Details of drivers for data electrodes, other than drivers for liquid crystal, plasma or OLED displays, not related to handling digital grey scale data or to communication of data to the pixels by means of a current
• CPC Class Codes: G09G 2310/0297 Special arrangements with multiplexing or demultiplexing of display data in the drivers for data electrodes, in a pre-processing circuitry delivering display data to said drivers or in the matrix panel, e.g. multiplexing plural data signals to one D/A converter or demultiplexing the D/A converter output to multiple columns
• CPC Class Codes: G09G 2310/04 Partial updating of the display screen
• CPC Class Codes: G09G 2310/06 Details of flat display driving waveforms
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2360/18 Use of a frame buffer in a display terminal, inclusive of the display panel
• 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 3/2092 Details of a display terminals using a flat panel, the details relating to the control arrangement of the display terminal and to the interfaces thereto suitable for both CRT and flat panel G09G5/003; specific for a CRT G09G1/165
• CPC Class Codes: G09G 3/3688 suitable for active matrices only

Abstract

In a display device using an RGB time division drive system in which RGB data to be supplied to display pixels of three colors RGB are subjected to time-division multiplexing and input to a liquid crystal panel unit, (1) data are input to the liquid crystal panel unit alternately in the order of RGB and BGR every line signal, and a selection signal SC which is in the on-state at a break of one line period is kept in the on-state until the next line period. In addition, (2) over a partial non-display period in partial display, selection signals SA, SB and SC are always in the off-state and an equalize signal EQG is in the on-state.

Claims

1. A display device comprising:

a pixel unit formed by forming a common electrode on an inner surface of one of two substrates disposed so as to be opposed to each other across a liquid crystal layer, forming a plurality of row electrodes and a plurality of column electrodes intersecting each other on an inner surface of the other of the two substrates, forming three-terminal switching elements respectively at intersections of the row electrodes and the column electrodes, connecting a first terminal of each of the switching elements to one of the row electrodes, connecting a second terminal of the switching element to one of column electrodes, connecting a third terminal of the switching element to one end of the liquid crystal layer and a retained capacitance, and connecting the other end of the liquid crystal layer to the common electrode;

a column drive circuit for converting display data input from an external device to a column voltage, generating a display synchronizing signal for liquid crystal drive, conducting time-division multiplexing on column voltages associated with one row in accordance with the display synchronizing signal, and outputting resulting time-division multiplexed column voltages;

a distributor circuit for distributing the time-division multiplexed column voltages supplied from the column drive circuit and outputting the distributed column voltages to the column electrodes;

a row drive circuit for outputting row voltages to the row electrodes row by row in accordance with the display synchronizing signal, in order to control turning on/off of the switching elements; and

a power supply circuit for outputting the display synchronizing signal to the row drive circuit, outputting a common voltage to the common electrode, and outputting selection signals to the distributor circuit,

wherein a first column electrode selected lastly in a frame, when a selection signal is in a selection state, for an arbitrary row electrode is selected first for a next row electrode in said frame and the first column electrode selected lastly in said frame for the arbitrary row electrode is kept selected, and the selection signal remains in said selection state, until a different second column electrode is selected for the next row electrode in said frame, wherein said frame comprises a period from a frame signal to a next frame signal.

2. The display device according to claim 1, further comprising a changeover function for changing over the following cases A and B:

case A;

when the selection signals are not changed in level, display is conducted with a small number of gray scale levels,

case B;

when the selection signals are changed in level, display is conducted with a large number of gray scale levels.

3. A display device comprising:

a pixel unit formed by forming a common electrode on an inner surface of one of two substrates disposed so as to be opposed to each other across a liquid crystal layer, forming a plurality of row electrodes and a plurality of column electrodes intersecting each other on an inner surface of the other of the two substrates, forming three-terminal switching elements respectively at intersections of the row electrodes and the column electrodes, connecting a first terminal of each of the switching elements to one of the row electrodes, connecting a second terminal of the switching element to one of column electrodes, connecting a third terminal of the switching element to one end of the liquid crystal layer and a retained capacitance, and connecting the other end of the liquid crystal layer to the common electrode;

a column drive circuit for converting display data input from an external device to a column voltage, generating a display synchronizing signal, conducting time-division multiplexing on column voltages associated with one row in accordance with the display synchronizing signal, and outputting resulting time-division multiplexed column voltages;

a distributor circuit for distributing the time-division multiplexed column voltages supplied from the column drive circuit and outputting the distributed column voltages to the column electrodes;

a row drive circuit for outputting row voltages to the row electrodes row by row in accordance with the display synchronizing signal, in order to control turning on/off of the switching elements; and

a power supply circuit for outputting the display synchronizing signal to the row drive circuit, outputting a common voltage to the common electrode, and outputting selection signals to the distributor circuit,

wherein;

the display data is changed over every plural rows, and

a first column electrode selected lastly in a frame, when a selection signal is in a selection state, for an arbitrary row electrode is selected first for a next row electrode in said frame and the first column electrode selected lastly in said frame for the arbitrary row electrode is kept selected, and the selection signal remains in said selection state, until a different second column electrode is selected for the next row electrode in said frame, wherein said frame comprises a period from a frame signal to a next frame signal.

4. A display device comprising:

a plurality of row electrodes;

a plurality of column electrodes intersecting the row electrodes;

display elements arranged in the intersections of the row electrodes and the column electrodes; and

a distributor circuit for selecting column electrodes by using a division unit obtained by dividing the column electrodes into a plurality of parts,

wherein;

the distributor circuit successively selects respective column electrodes with the division unit in accordance with a plurality of selection signals, and

a first column electrode selected lastly in a frame, when a selection signal is in a selection state, for an arbitrary row electrode is selected first for a next row electrode in said frame and the first column electrode selected lastly in said frame for the arbitrary row electrode is kept selected, and the selection signal remains in said selection state, until a different second column electrode is selected for the next row electrode in said frame, wherein said frame comprises a period from a frame signal to a next frame signal.

5. The display device according to claim 4, wherein over a non-display period in partial display, the selection signals are kept in an off-state.

6. A display device comprising:

a pixel unit formed so as to be associated with switching elements formed respectively at intersections of a plurality of row electrodes and a plurality of column electrodes, and a common electrode;

a column drive circuit for converting display data input from an external device to a column voltage, generating a display synchronizing signal, conducting time-division multiplexing on column voltages associated with one row in accordance with the display synchronizing signal, and outputting resulting time-division multiplexed column voltages;

a distributor circuit for distributing the time-division multiplexed column voltages supplied from the column drive circuit and outputting the distributed column voltages to the column electrodes;

a row drive circuit for outputting row voltages to the row electrodes row by row in accordance with the display synchronizing signal, in order to control turning on/off of the switching elements; and

a power supply circuit for outputting the display synchronizing signal to the row drive circuit, outputting a common voltage to the common electrode, and outputting selection signals to the distributor circuit,

wherein a first column electrode selected lastly in a frame, when a selection signal is in a selection state, for an arbitrary row electrode is selected first for a next row electrode in said frame and the first column electrode selected lastly in said frame for the arbitrary row electrode is kept selected, and the selection signal remains in said selection state, until a different second column electrode is selected for the next row electrode in said frame, wherein said frame comprises a period from a frame signal to a next frame signal.