Fast warm-up heater for liquid crystal display

• US 4,773,735 A
• Filed: 08/04/1986
• Issued: 09/27/1988
• Est. Priority Date: 08/04/1986
• Status: Expired due to Term

• Current Assignee: Alliedsignal Inc.
• Original Assignee: Alliedsignal Inc.
• Inventors: Levine, Alfred L., Ukrainsky, Orest J.
• Primary Examiner(s): Heyman, John S.
• Assistant Examiner(s): Phan, Trong Quang
• Application Number:
  US06/892,628
• Time in Patent Office: 785 Days
• Field of Search: 350/331 T, 350/336, 350/351, 357/28, 372/34, 372/36, 250/238
• US Class Current: 349/161
• CPC Class Codes: G02F 1/133382 Heating or cooling of liquid crystal cells other than for activation, e.g. circuits or arrangements for temperature control, stabilisation or uniform distribution over the cell

Abstract

A solid state device such as a liquid crystal display (LCD 11) is provided with fast warm up characteristics by using an internal heater (31). The internal heater (31) preferably is located on a backplane, (13) and is used during warmup to supplement a conventional heater (41). The external heater (41) permits the LCD heater system to operate continuously at a selected temperature and not cause deterioration of the LCD (11). The internal heater (31) is electrically isolated from the device'"'"'s backplane electrodes (17), for example, by the use of a thin oxide layer (33) between the internal heater (31) and the backplane electrodes (17).

Claims

1. Solid state device in which active portions of the solid state device are supported by an insulating substrate, and in which the device is temperature sensitive in its operating characteristics, characterized by:

(a) an internal heating element interposed between the active elements of the device and the insulating substrate;

(b) a further insulating layer interposed between the internal heating element and the active elements of the device, so that the internal heating element is at least partially separated from the active elements by the insulating layer, with the insulating substrate providing physical support for the internal heating element and at least some of the active elements of the solid state device; and

(c) an external heating element mounted to the insulating substrate, so that the external heating element is separated from the active elements by the insulating substrate.

2. Solid state device as described in claim 1, further characterized by:

(a) means to provide a first power level to the internal heater at an initial time period and to reduce the power level to the internal heater subsequent to the internal time period.

(b) an external heating element mounted to the insulating substrate on an external side of insulating substrate, so that the external heating element is separated from the active elements by the insulating substrate.

3. Solid state device in which active portions of the solid state device are supported by an insulating substrate, and in which the device is temperature sensitive in its operating characteristics, characterized by:

5. Solid state device as claimed in claim 3 characterized by:

means to provide a first power level to the internal heating element at an initial time period and to reduce the power level to the internal heating element subsequent to the initial time period.

6. Solid state device as described in claim 3, further characterized by:

means to provide a first power level to the internal heating element at an initial time period and to reduce the power level to the internal heater subsequent to the initial time period.

8. Liquid crystal display as described in claim 6, further characterized by:

means to provide a first power level to the internal heating element at an initial time period and to reduce the power level to the internal heating element subsequent to the initial time period.

9. Liquid crystal display as described in claim 6, further characterized by:

means to provide a first power level to the internal heating element subsequent to the initial time period.

10. Liquid crystal display as described in claim 6, further characterized by:

means to provide a first power level to the internal heating element at an initial time period and to reduce the power level to the internal heater subsequent to the initial time period.

12. Liquid crystal display as described in claim 10, further characterized by:

masking means to obsecure some of a biasing effect on the liquid crystal substance which may be caused by the interspaced heating element.

15. Liquid crystal display as described in claim 10, further characterized by:

means to provide a first power level to the internal heating element at an initial time period and to reduce the power level to the internal heating element subsequent to the initial time period.

4. (a) an internal heating element interposed between the active elements of the device and the insulating substrate;

and

(b) an external heating element mounted to the insulated substrate on an external side of the insulating substrate, so that the external heating element is separated from the active elements by the insulating substrate.

7. Liquid crystal display in which liquid crystal substance is contained between a front member and a back member and in which an array of electrodes is used to change the optical state of the liquid crystal substance in order to provide a plurality of display segments, and in which the liquid crystal display is provided with a heater for establishing the liquid display substance to a preferred operating temperature range, characterized by:

(a) an internal heating element interposed between the arrays of electrodes and at least one of the front and back members;

(b) an insulating layer, distinct from the back and front members, interposed between the arrays of electrodes and he heating element;

(c) at least one of the arrays of electrodes juxtaposed to the insulating layer, with the internal heating elements being supported by the said one of the members, and in turn supporting the insulating layer, which in turn supports said one of the array of the electrodes, the insulating layer electrically separating the internal heating element from the electrodes;

(d) said one of the members being a backplane for the liquid display device, so that the internal heating element is juxtaposed to the backplane of the liquid crystal device; and

,

(e) a second heating element, external to the members, so that heat generated by the second heating element must be transferred through the member to which it is attached in order to provide heat to the liquid crystal display substance.

11. Liquid crystal display in which liquid crystal substance is contained between a front member and a back member and in which an array of electrodes is used to change the optical state of the liquid crystal substance in order to provide a plurality of display segments, and in which the liquid crystal display is provided with a heater for establishing the liquid display substance to a preferred operating temperature range, characterized by:

(a) an internal heating element interspaced between a plurality of said electrodes;

(b) a second heating element, external to the members, so that heat generated by the second heating element must be transferred through the member in which it is attached in order to provide heat to the liquid crystal substance.

13. Liquid crystal display as described in claim 11, further characterized by:

14. means to provide a first power level to the internal heating element at an initial time period and to reduce the power level to the internal heating element subsequent to the initial time period.