Saturating column driver for grey scale LCD

• US 5,061,920 A
• Filed: 02/14/1991
• Issued: 10/29/1991
• Est. Priority Date: 12/20/1988
• Status: Expired due to Term

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Inventors: Nelson, Larry A.
• Primary Examiner(s): Brier, Jeffery A.
• Application Number:
  US07/656,128
• Time in Patent Office: 257 Days
• Field of Search: 340/718, 340/719, 340/767, 340/793, 340/765, 340/784, 340/811, 358/32, 358/236, 358/230
• US Class Current: 345/89
• 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 2360/123 using interleaving
• CPC Class Codes: G09G 2360/18 Use of a frame buffer in a display terminal, inclusive of the display panel
• CPC Class Codes: G09G 3/006 Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays testing individual LED's G01R31/2635; testing lamps G01R31/44; testing of optical features of LCD displays G02F1/1309
• CPC Class Codes: G09G 3/2011 by amplitude modulation
• 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 3/3611 Control of matrices with row and column drivers
• CPC Class Codes: G09G 3/3688 suitable for active matrices only

Abstract

A saturating column driver for an LCD substrate. Digital data is entered into a register in a serial fashion to produce a series of single-column addresses. The single-column addresses are latched and apparatus is provided for translating video binary words into grey scale codes. Also provided are switches responsive to the translated video binary words which switch a voltage input corresponding to the video binary word through to the LCD substrate to generate the desired grey scale.

Claims

1. A saturating column driver for an LCD substrate comprising:

register means for entering digital data in a serial fashion to produce a single-column address including a video binary word;

means for latching the single-column address connected to the register means;

unclocked means for translating the video binary word into a plurality of grey scale coded bits connected to the latching means;

a plurality of switching means for switching each of said plurality of switching means having an input terminal, an output terminal and a control terminal wherein the control terminal is connected to one of the grey scale coded bits and wherein each output terminal is connected to one column of the LCD substrate; and

a plurality of voltage generator means for generating a plurality of electronic signals connected to each input terminal so that when the switching means is activated the voltage generator means supplies one electronic signal through the switching means to drive the LCD substrate.

2. The apparatus of claim 1 wherein the register means comprises a shift register.

3. The apparatus of claim 1 wherein the latching means comprises a digital flip-flop circuit.

4. The apparatus of claim 1 wherein the translating means comprises a demultiplexer.

5. The apparatus of claim 4 wherein the demultiplexer comprises a plurality of 4 to 16 bit demultiplexers.

6. The apparatus of claim 1 wherein the plurality of voltage generator means comprise pre-set voltages.

7. The apparatus of claim 6 wherein the plurality of pre-set voltages are generated through an external voltage connected through a voltage divider string.

8. The apparatus of claim 1 wherein the plurality of voltage generator means vary incrementally in equal increments.

9. The apparatus of claim 1 wherein the plurality of voltage generator means vary in accordance with the dynamics of a video camera.

10. The apparatus of claim 1 wherein the plurality of voltage generator means includes at least 16 pre-set voltage levels.

17. The apparatus of claim 1 wherein the plurality of switches comprise transistors.

11. Apparatus for providing grey scale for use in a video interface having a LCD substrate comprising:

(a) a shift register for entering digital data in a serial fashion to produce a single-column address including a video binary word;

(b) a latch connected to the shift register for latching the video binary word;

(c) a demultiplexer for decoding the video binary word into a plurality of grey scale coded bits;

(d) a level shifter for shifting the voltage level of the grey scale coded bits from a logical level to a switching level;

(e) a plurality of switches having an input pole and an output pole connected to the level shifter and responsive to one of each of the grey scale coded bits; and

(f) a plurality of preset voltages each connected to the input pole of one of the switches so that when the switch is closed the preset voltage is passed through to the LCD substrate.

12. The apparatus of claim 11 wherein the demultiplexer comprises a plurality of 4 to 16 bit demultiplexers.

13. The apparatus of claim 11 wherein the plurality of pre-set voltages are generated through an external voltage connected through a voltage divider string.

14. The apparatus of claim 11 wherein the plurality of pre-set voltages vary incrementally in equal increments.

15. The apparatus of claim 11 wherein the plurality of pre-set voltages vary in accordance with the dynamics of a video camera.

16. The apparatus of claim 11 wherein the plurality of pre-set voltages includes at least 16 pre-set voltage levels.

18. The apparatus of claim 11 wherein the plurality of switches comprise transistors.

19. Apparatus for providing grey scale for use in a video interface having a LCD substrate comprising:

(a) a shift register for entering digital data in a serial fashion to produce a single-column address including a video binary word;

(b) a latch connected to the shift register for latching the video binary word;

(c) a demultiplexer for decoding the video binary word into a plurality of grey scale coded bits;

(d) a level shifter for shifting the voltage level of the grey scale coded bits from a logic level to a switching level;

(e) a pluralilty of switches having an input pole and an output pole connected to the level shifter and responsive to one of each of the grey scale coded bits; and

(f) a plurality of preset voltages each connected to the source of one of the FETs so that when the FET is turned on the preset voltage is passed through to the LCD substrate, wherein the plurality of preset voltages are generated through an external voltage source comprising a voltage divider string.

20. The apparatus of claim 19 wherein an external generator is connected through a second plurality of switches to the plurality of preset voltages so as to allow signals generated by the external generator to be substituted for any or all of the preset voltages.