Liquid crystal display with integral heater and method of fabricating same

• US 5,559,614 A
• Filed: 05/01/1995
• Issued: 09/24/1996
• Est. Priority Date: 05/01/1995
• Status: Expired due to Fees

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Swirbel, Thomas J., Urbish, Glenn F., Dorinski, Dale W.
• Primary Examiner(s): Gross, Anita Pellman
• Assistant Examiner(s): TON, MINH TOAN T
• Application Number:
  US08/432,346
• Time in Patent Office: 512 Days
• Field of Search: 359/44, 359/86, 359/87
• US Class Current: 349/21
• 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 liquid crystal display device (11) is made by sputtering a layer of indium-tin oxide and copper on a transparent substrate. This metal layer is photodelineated to form a pattern of electrodes (17) and heating elements (81), the heating elements being interlaced between the electrodes. The heating elements are converted to a more resistive form by applying a constant voltage signal to only the heating elements in an oxygen-containing atmosphere. The assembled LCD has the heating elements on the inside of the display, so that when the heating elements are pulsed, they heat only a portion of the liquid crystal fluid in the immediate proximity. The heaters are activated by a signal from a display driver.

Claims

1. A liquid crystal display device with integral heating elements, comprising:

first and second substrates, each having an active face, the substrates;

arranged in parallel fashion to form a uniform gap between them;

a plurality of electrodes, comprising a thin film of indium-tin oxide and copper, disposed directly on the active face of each substrate;

internal heating means, comprising a thin film of indium-tin oxide and copper oxide resistive heating elements interlaced among and between the plurality of electrodes, the internal heating means disposed directly on the active face of at least one of the substrates;

a liquid crystal fluid disposed in the uniform gap, in intimate contact with and responsive to the internal heating means; and

absent an external heating mean.

2. A liquid crystal display device with integral heating elements, comprising:

first and second substrates, each having an active face, the substrates arranged in parallel fashion to form a uniform gap between them;

a plurality of electrodes disposed directly on the active face of each substrate;

internal heating means, comprising a plurality of resistive heating elements interlaced among and between the plurality of electrodes, the internal heating means disposed directly on the active face of at least one of the substrates;

the plurality of resistive heating elements having a sheet resistivity of about 10-1000 times greater than the sheet resistivity of the plurality of electrode;

a liquid crystal fluid disposed in the uniform gap, in intimate contact with and responsive to the internal heating means; and

absent an external heating means.

3. A liquid crystal display device for operation at subambient temperatures, comprising:

first and second substrates, each having an active face, the substrates arranged in parallel fashion to form a uniform gap between them;

a plurality of electrodes comprising a thin film of indium-tin oxide and copper disposed on the active face of at least one substrate;

a plurality of heating elements comprising a thin film of indium-tin oxide and copper oxide disposed on the active face of at least one substrate;

the plurality of heating elements having a sheet resistivity between 10 and 1000 times greater than a sheet resistivity of the plurality of electrodes, and interlaced among and between the plurality of electrodes; and

and a liquid crystal medium disposed in the uniform gap, a portion of the liquid crystal medium in the proximity of the plurality of heating elements being dependent on transient heating by circulation of an electric current within at least one of the plurality of heating elements, absent an external heater.

4. The liquid crystal display device as described in claim 3, further comprising a means for generating data, connected to the plurality of electrodes.

5. The liquid crystal display device as described in claim 3, further comprising a thermal addressing means, connected to the plurality heating elements, for selectively addressing the plurality of heating elements.

6. The liquid crystal display device as described in claim 3, wherein the plurality of heating elements is optically transparent.

7. A method of fabricating heater elements and electrodes for a liquid crystal display, comprising the following steps in the order named:

forming a composite metal layer on the surface of a glass substrate by sputtering a layer of indium-tin oxide on the glass surface and then sputtering a layer of copper on the indium-tin oxide layer;

photodelineating the composite metal layer to form a pattern comprising electrodes and heating elements, the heating elements being interlaced between the electrodes; and

applying an electrical signal to only the heating elements in an oxygen-containing atmosphere, sufficient to cause the heating elements to heat to a temperature sufficient to cause the sheet resistance of the heating elements to increase to a level greater than 1000 ohms per square.

8. The method as described in claim 7, wherein the step of applying an electrical signal comprises applying a constant voltage signal.