System for applying grey scale codes to the pixels of a display device

• US 4,742,346 A
• Filed: 12/19/1986
• Issued: 05/03/1988
• Est. Priority Date: 12/19/1986
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: RCA Corporation (General Electric Company)
• Inventors: Gillette, Glynn G., Fischer, John T., Stewart, Roger G.
• Primary Examiner(s): Caldwell, Sr., John W.
• Assistant Examiner(s): Holloway, III, Edwin C.
• Application Number:
  US06/943,709
• Time in Patent Office: 501 Days
• Field of Search: 340/784, 340/793, 340/767, 340/805, 340/703, 340/802, 340/801, 340/800, 358/241, 358/236, 358/168, 358/283
• US Class Current: 345/89
• CPC Class Codes: G09G 2310/0259 with use of an analog or digital ramp generator in the column driver or in the pixel circuit
• CPC Class Codes: G09G 2310/027 Details of drivers for data electrodes, the drivers handling digital grey scale data, e.g. use of D/A converters
• 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 3/2011 by amplitude modulation
• CPC Class Codes: G09G 3/3688 suitable for active matrices only

Abstract

A system for applying grey scale codes to a display device having a plurality of columns of pixels, has a segmented shift register, with one shift register segment for each pixel column. Data stored in the shift register segments are transferred to counters through multiplex circuitry. The counters control transfer gates by which voltages are applied to the pixel columns.

Claims

1. A system for applying a plurality of digital grey scale codes to the pixels of a display device composed of an array of pixels arranged vertically in Y columns and horizontally in rows comprising:

shift register means for receiving and storing said grey scale codes for said columns, said shift register means having a plurality of groups, each of said groups having a plurality of segments whereby said shift register means includes Y shift register segments and each segment stores said grey scale codes for a particular column and provides said grey scale codes to said particular column;

a plurality of Y multiplex means individually responsive to said shift register segments for receiving said grey scale codes;

a plurality of counters individually responsive to said multiplex means for receiving said grey scale codes from said shift register segments to set said counters to counts equal to said grey scale codes whereby said counters count down from said counts to zero; and

a plurality of transfer circuit means, each of said transfer circuit means including a latch circuit responsive to one of said counters and a transfer gate responsive to said latch circuit, said transfer gates being conductive when said counters are counting and nonconductive after said counters have counted to zero whereby said transfer gates are conductive in accordance with the grey scale codes received from said shift register segments.

2. The system of claim 1 wherein pixels are liquid crystals.