LEP electroluminescent backlit keypad for a cellular phone

• US 5,971,557 A
• Filed: 11/13/1996
• Issued: 10/26/1999
• Est. Priority Date: 11/13/1996
• Status: Expired due to Term

• Current Assignee: Optis Cellular Technology LLC (Brevet Capital)
• Original Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Smith, James A., Kubes, Joseph
• Primary Examiner(s): O'Shea, Sandra
• Assistant Examiner(s): HONEYMAN, MARSHALL S
• Application Number:
  US08/747,846
• Time in Patent Office: 1,077 Days
• Field of Search: 313/505, 313/506, 313/503, 313/510, 362/84, 362/88, 362/109, 362/253, 362/24
• US Class Current: 362/24
• CPC Class Codes: B33Y 80/00 Products made by additive manufacturing
• CPC Class Codes: H01H 13/702 with contacts carried by or formed from layers in a multilayer structure, e.g. membrane switches
• CPC Class Codes: H01H 2219/018 Electroluminescent panel
• CPC Class Codes: H01H 2219/02 programmable
• CPC Class Codes: H01H 2219/037 using organic materials, e.g. organic LED
• CPC Class Codes: H04M 1/22 Illumination; Arrangements for improving the visibility of characters on dials

Abstract

An electroluminescent backlit device utilizing light-emitting polymers (LEP) is disclosed. A sandwich of LEP material and two electrical conductive materials are used to provide back lighting for a keypad or display. The electrical conductive layers are etched to form channels which provide current to and excite the LEP material to produce light at predetermined points. The etchings are directed around existing electrical contacts to facilitate normal operation of the underlying host system, such as a cellular telephone.

Claims

1. An electroluminescent keypad for use with a host system including electrical components, comprising:

a substrate material;

a keypad including at least one key;

at least one layer of light-emitting polymer material;

a first layer of electrical conductive material connected to a power supply and located along a bottom surface of the layer of light-emitting polymer material;

a second layer of electrical conductive material connected to the power supply and located along a top surface of the layer of light-emitting polymer material;

said first layer of electrical conductive material and said second layer of electrical conductive material providing current to the layer of light-emitting polymer material at predetermined points, causing said layer of light-emitting polymer material to produce light at such predetermined points;

said first electrical conductive layer etched along its surface in a first direction to form a first set of channels and said second electrical conductive layer etched along its surface in a direction perpendicular to said first direction to form a second set of channels, said first set and said second set of channels capable of conducting electricity along said channels; and

wherein said first set of channels and said second set of channels are etched to avoid interrupting electrical contact between said at least one key and said electrical components of the host system.

2. The electroluminescent keypad of claim 1, wherein the predetermined points at which the layer of light-emitting polymer material will produce light are defined by points on the layer of light-emitting polymer material where the first set of channels along the bottom surface of the layer of light-emitting polymer material intersect with the second set of channels along the top surface of the layer of light-emitting polymer material.

3. The electroluminescent keypad of claim 1, wherein the substrate material is selected from the group consisting of plastic, fiberglass, polyamide, polycarbonate or fluorohalo carbon.

4. The electroluminescent keypad of claim 1, wherein the keypad is constructed of a clear or translucent material.

5. The electroluminescent keypad of claim 1, wherein the first layer of electrical conductive material is composed of aluminum.

6. The electroluminescent keypad of claim 1, wherein the second layer of electrical conductive material is composed of indium tin oxide.

7. The electroluminescent keypad of claim 1, wherein the layer of light-emitting polymer material, the first layer of electrical conductive material and the second layer of electrical conductive material are formed using a print screen technique.

8. The electroluminescent keypad of claim 1, wherein the layer of light-emitting polymer material, the first layer of electrical conductive material and the second layer of electrical conductive material are formed using a vacuum deposition technique.

9. The electroluminescent keypad of claim 1, wherein the at least one layer of light-emitting polymer material further includes a coating of material to seal the at least one layer of light-emitting polymer material against exposure to moisture and oxygen.

10. The electroluminescent keypad of claim 1, wherein the host system is a personal communication device.

11. The electroluminescent keypad of claim 10, wherein the personal communication device is a cellular telephone.

12. An electroluminescent display for use with a host system, said host system including electrical components, said electroluminescent display comprising:

a substrate material;

a display surface;

at least one light-emitting polymer (LEP) layer;

a first electrical conductive material (ECM) layer connected to a power supply and located along a bottom surface of the at least one LEP layer, said first ECM layer including a first set of channels etched in a first direction into the its surface, said first set of channels capable of conducting electricity along their length;

a second ECM layer connected to the power supply and located along a top surface of the at least one LEP layer, said second ECM layer including a second set of channels etched in a direction perpendicular to the first direction, said second set of channels capable of conducting electricity along their length;

said first set of channels and said second set of channels crossing at a multiplicity of predetermined points along the LEP layer;

said first ECM layer and said second ECM layer providing current to the at least one LEP layer at the predetermined points on its surface, causing said at least one LEP layer to produce light at such predetermined points; and

wherein said first set of channels and said second set of channels are etched to avoid interrupting electrical contact between said electrical components of the host system.

13. The electroluminescent display of claim 12, wherein the first ECM layer is composed of aluminum.

14. The electroluminescent display of claim 12, wherein the second ECM layer is composed of indium tin oxide.

15. The electroluminescent display of claim 12, wherein the first ECM layer is composed of a material having a high dielectric constant.

16. The electroluminescent display of claim 12, wherein the second ECM layer is composed of a material having a low dielectric constant.

17. The electroluminescent display of claim 12, wherein the host system is a cellular telephone.

18. The electroluminescent display of claim 12, wherein the display surface is composed of a clear or translucent material.