Touch panel with PDLC film and touch-sensitive display device using same

• US 8,581,860 B2
• Filed: 02/26/2010
• Issued: 11/12/2013
• Est. Priority Date: 11/12/2009
• Status: Active Grant

• Current Assignee: InnoLux Corporation
• Original Assignee: Chi Mei Innolux Corporation (InnoLux Corporation), Innocom Technology (Shenzhen) Co., Ltd. (InnoLux Corporation)
• Inventors: Meng, Kai
• Primary Examiner(s): Lao, Lun-Yi
• Assistant Examiner(s): SHAH, PRIYANK J
• Application Number:
  US12/713,307
• Publication Number:
  US 20110109566A1
• Time in Patent Office: 1,355 Days
• Field of Search: 345/87, 345/90, 345/104, 345/107, 345/173, 345/174, 349 61- 63, 349 86- 89, 178/18.01, 178/18.03, 178/18.06
• US Class Current: 345/173
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

A touch panel and a touch-sensitive display device capable of providing three-dimensional contact detection are provided. The touch panel includes a first conductive layer, a second conductive layer, and an insulating layer between the first and second conductive layers. The insulating layer includes a polymer dispersed liquid crystal (PDLC) film.

Claims

1. A touch panel connecting to a driving circuit, comprising:

a first conductive layer;

a second conductive layer; and

an insulating layer between the first and second conductive layers;

wherein the insulating layer comprises a polymer dispersed liquid crystal (PDLC) film and a relative permittivity of the PDLC film increases when a thickness of the PDLC film is reduced, wherein a plurality of overlapping capacitors are cooperatively defined by the first and second conductive layers and the insulating layer therebetween; and

wherein the driving circuit detects an X-axis coordinate and a Y-axis coordinate of a contact point on the touch panel by detecting one or more capacitance variations of one or more of the overlapping capacitors that correspond to the contact point, and detects a Z-axis coordinate of the contact point by calculating one or more capacitance increments of said one or more of the overlapping capacitors;

wherein the PDLC film comprises a plurality of liquid crystal drops dispersed in the polymer material, and the polymer material is characterized in that it operates to vertically align liquid crystal molecules of the liquid crystal drops;

wherein a shape of each of the liquid crystal drops is substantially spherical when no external force is applied to the PDLC film, and when external force is applied to the PDLC film, at least one of the liquid crystal drops reforms from substantially spherical to a generally ellipsoidal shape; and

wherein when the external force is applied to the PDLC film, the liquid crystal molecules in each of said at least one of the liquid crystal drops realign from radiating outwards from a spherical center to a more parallel distribution relative to each other.

2. The touch panel of claim 1, wherein the first conductive layer comprises a plurality of first conductive lines, the second conductive layer comprises a plurality of second conductive lines crossing the first conductive lines, and the plurality of overlapping capacitors are formed at the intersections between the first and second conductive lines, wherein a capacitance of each of the overlapping capacitors is variable.

3. The touch panel of claim 1, wherein an arrangement of the liquid crystal molecules of each of the liquid crystal drops is variable in response to external force applied to the PDLC film.

4. The touch panel of claim 1, wherein when no external force is applied to the PDLC film, the liquid crystal molecules of each of the liquid crystal drops are arranged radiating outwards from the spherical center of the liquid crystal drop.

5. A touch-sensitive display device, comprising:

a touch panel comprising a first conductive layer, a second conductive layer, and an insulating layer therebetween;

wherein the insulating layer comprises a polymer dispersed liquid crystal (PDLC) film and a relative permittivity of the PDLC film increases when a thickness of the PDLC film is reduced, wherein a plurality of overlapping capacitors are cooperatively defined by the first and second conductive layers and the insulating layer therebetween; and

a driving circuit configured for detecting an X-axis coordinate and a Y-axis coordinate of a contact point on the touch panel by detecting one or more capacitance variations of one or more of the overlapping capacitors that correspond to the contact point, and detecting a Z-axis coordinate of the contact point by calculating one or more capacitance increments of said one or more of the overlapping capacitors;

wherein the PDLC film comprises a plurality of liquid crystal drops dispersed in the polymer material, and the polymer material is characterized in that it operates to vertically align liquid crystal molecules of the liquid crystal drops;

wherein a shape of each of the liquid crystal drops is substantially spherical when no external force is applied to the PDLC film, and when external force is applied to the PDLC film at the contact point, at least one of the liquid crystal drops reforms from substantially spherical to a generally ellipsoidal shape; and

wherein when the external force is applied to the PDLC film at the contact point, the liquid crystal molecules in each of said at least one of the liquid crystal drops realign from radiating outwards from a spherical center to a more parallel distribution relative to each other.

6. The touch-sensitive display device of claim 5, wherein the first conductive layer comprises a plurality of first conductive lines, the second conductive layer comprises a plurality of second conductive lines crossing the first conductive lines, and the overlapping capacitors are formed at the intersections between the first and second conductive lines.

7. The touch-sensitive display device of claim 6, wherein the driving circuit detects an X-axis coordinate and a Y-axis coordinate of the contact point by determining an overlapping capacitor of said one or more of the overlapping capacitors having the greatest capacitance variation.

8. The touch-sensitive display device of claim 7, wherein the driving circuit detects a Z-axis coordinate of the contact point by calculating the capacitance increment of the overlapping capacitor having the greatest capacitance variation.

9. The touch-sensitive display device of claim 5, wherein an arrangement of the liquid crystal molecules of at least one of the liquid crystal drops of said one or more of the overlapping capacitors is variable in response to external force applied to the PDLC film at the contact point.

10. The touch-sensitive display device of claim 5, wherein when no external force is applied to the PDLC film, the liquid crystal molecules of each of the liquid crystal drops radiate outwards from the spherical center of the liquid crystal drop.