Active matrix liquid crystal display

• US 6,633,306 B1
• Filed: 12/13/2000
• Issued: 10/14/2003
• Est. Priority Date: 03/13/1998
• Status: Expired due to Fees

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Wammes, Klaus, März, Michael
• Primary Examiner(s): Saras, Steven
• Assistant Examiner(s): Anyaso, Uchendu O.
• Application Number:
  US09/623,817
• Time in Patent Office: 1,035 Days
• Field of Search: 345/177, 345/208, 345/695, 345/696, 345/698, 345/3.3
• US Class Current: 345/698
• CPC Class Codes: G02F 1/1323 Arrangements for providing a switchable viewing angle
• CPC Class Codes: G09G 2300/0809 Several active elements per pixel in active matrix panels
• CPC Class Codes: G09G 2320/0606 Manual adjustment
• CPC Class Codes: G09G 2320/068 for control of viewing angle adjustment
• CPC Class Codes: G09G 3/2074 using sub-pixels
• CPC Class Codes: G09G 3/3607 for displaying colours or for displaying grey scales with a specific pixel layout, e.g. using sub-pixels display of colours in flat matrix panels other than liquid crystal displays G09G3/2003; grey scales specific for television H04N3/127
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: H04N 5/72 Modifying the appearance of television pictures by optical filters or diffusing screens

Abstract

In an active matrix liquid crystal display, pixels are arranged in rows and columns of a matrix and are controllable via row electrodes and column electrodes. To improve and to expand the possibilities of image rendering without increasing the number of rows and columns to be controlled, the pixels are divided into sub-pixels with corresponding sub-pixel electrodes, each of which is connected to the column electrode assigned to the pixel via controllable switches. On the control side, the controllable switches are connected to the row electrode assigned to the pixel via pixel control unit which is common to them. From a control signal supplied to it via the row electrode the pixel control unit generates locally and chronologically different turn-on signals for the various switches so that they switch chronologically successive different gray-scale levels of a gray-scale signal present at the column electrode through to the sub-pixel electrodes.

Claims

1. An active matrix liquid crystal display, comprising:

pixels arranged in rows and columns of a matrix, each of the pixels including at least two sub-pixels, and each of the pixels being formed from at least two adjacent sub-pixel electrodes, a reference electrode being common to the pixels, and a liquid crystal layer lying between the sub-pixel electrodes and the reference electrode;

row electrodes, a respective one of the row electrodes being assigned to each row of pixels;

column electrodes, a respective one of column electrodes being assigned to each column of the pixels;

a row control unit connected to the row electrodes and successively generating control signals for the rows of pixels;

a column control unit connected to the column electrodes and generating gray-scale signals having chronologically success gray-scale levels for the sub-pixels;

pixel control units individually assigned to the pixels; and

controllable switches individually assigned to the sub-pixels, the sub-pixel electrodes being connected to an assigned one of the column electrodes via a respective one of the controllable switches, a control side of the respective one of the controllable switches being connected to an assigned one of the row electrodes via one of the pixel control units assigned to the sub-pixels, each of the pixel control units generating locally and chronologically different turn-on signals for the controllable switches assigned to the sub-pixels from the control signals supplied via one of the row electrodes;

wherein each of the control signals includes individual, chronologically successive signal pulses, each of the pixel control units including an arrangement that converts the chronologically successive signal pulses into the locally and chronologically different turn-on signals.

2. The active matrix liquid crystal display according to claim 1, wherein each arrangement that converts the chronologically successive signal pulses includes one of:

i) a shift register, ii) a counter and iii) a serial-parallel converter.

3. The active matrix liquid crystal display according to claim 1, wherein each of the control signals includes a synchronizing pulse that is different from the signal pulses, and wherein each of the pixel control units includes an arrangement for recognizing the synchronizing pulse and for synchronizing the signal conversion.

4. The active matrix liquid crystal display according to claim 1, wherein color filters are assigned to the individual sub-pixels of each of the pixels.

5. The active matrix liquid crystal display according to claim 1, further comprising:

an adjustment device to variably adjust the chronologically successive gray-scale levels for the sub-pixels while preserving an average gray-scale level of all of the sub-pixels of a pixel.

6. The active matrix liquid crystal display according to claim 1, wherein the column control unit includes an arrangement to sequentially arrange the gray-scale levels, delivered by at least two different image signal sources, in the gray-scale signals generated by the column control unit.

7. The active matrix liquid crystal display according to claim 1, wherein in an area of each individual one of the pixels, the liquid crystal layer is divided into domains having different orientations of liquid crystals, the domains being assigned to the individual sub-pixels of the individual one of the pixels.

8. The active matrix liquid crystal display according to claim 1, wherein the pixel control units, together with the sub-pixel electrodes, the controllable switches, the row electrodes and the column electrodes are arranged on a common carrier.

9. The active matrix liquid crystal display according to claim 1, wherein the active matrix liquid crystal display is arranged in a vehicle approximately centered in from of laterally adjacent passenger seats.