Digitizer

• US 6,670,949 B1
• Filed: 07/19/2000
• Issued: 12/30/2003
• Est. Priority Date: 07/19/1999
• Status: Expired due to Term

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Philips LCD Company Limited (LG Display Co., Ltd.)
• Inventors: Ahn, Young-Soo, Jeong, Yun-Cheol, Oh, Young-Jin
• Primary Examiner(s): Saras, Steven
• Assistant Examiner(s): Anyaso, Uchendu O.
• Application Number:
  US09/619,538
• Time in Patent Office: 1,259 Days
• Field of Search: 178/18.03, 178/18.05, 345/173, 345/174, 345/177, 345/178, 345/179, 349/12
• US Class Current: 345/173
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact

Abstract

An apparatus for locating a point physically touched and producing an electrical signal corresponding to the location includes an insulating substrate; a resistor touch pattern supported on the insulating substrate; and a protective insulating plate arranged over the resistive touch pattern. The resistive touch pattern has a plurality of strip resistors parallel to a center line; a plurality of linear resistors connected to the strip resistors, the resistance of the linear resistors decreasing with distance from the center line; first and third terminals positioned on an intermediate point of alternate edges of the touch pattern; and second and fourth terminals, positioned on an intermediate point of other alternate edges of the touch pattern. The resistive value of the linear resistors selected for a corresponding strip resistor so as to produce equal potential at a corresponding selected point on all said strip resistors.

Claims

1. A touch panel for sensing a point contacted on a display, comprising:

a plurality of strip resistors parallel to one another, each of said strip resistors having first and second ends;

a plurality of electric signal terminals, first and third of said electric signal terminals located, respectively, on first and third edge portions of the touch panel, said first and third edge portions being opposite one another;

second and fourth of said electric signal terminals located, respectively, on second and fourth edge portions of the touch panel, second and fourth edge portions being opposite one another and containing an edge resistor, wherein each of said electric signal terminals is located at the midpoint of its respective edge portion; and

a plurality of linear resistors, wherein, for each strip resistor, a first respective one of said linear resistors is connected between the first end of said corresponding strip resistor and one of said electric signal terminals and a second respective one of said linear resistors is connected between the second end of the corresponding strip resistor and another of said electric signal terminals, each of said linear resistors having a resistive value selected for its corresponding strip resistor so as to produce equal potential at a corresponding selected point on all said strip resistors.

2. The touch panel of claim 1, wherein the distance between said selected point and said first end is the same for each of said strip resistors.

3. The touch panel of claim 1, wherein the touch panel has a rectangular configuration.

4. The touch panel of claim 1, wherein said first and third electric signal terminals and said second and fourth electric signal terminals are connected to alternately receive electrical signals from a drive circuit.

5. The touch panel of claim 1, further comprising:

at least two edge resistors parallel to the strip resistors, and each of said edge resistors located adjacent to said second and fourth edge portions, respectively,

wherein said second and fourth electric signal terminals are connected to a respective one of said edge resistors.

6. The touch panel of claim 1, wherein said second and fourth edge portions are parallel to said strip resistors.

7. The touch panel of claim 1, wherein the length of each of said linear resistors is equal.

8. The touch panel of claim 1, wherein the resistive value of the linear resistors corresponding to a strip resistor near one of said second and fourth edge portions is less than the resistive value of the linear resistors closer to the center of the touch panel.

9. The touch panel of claim 1, wherein the resistive value of said first respective one of said linear resistors is equal to the resistive value of said second respective one of said linear resistors.

10. The touch panel of claim 6, further comprising:

at least two chain resistors, perpendicular to said edge resistors, each of said chain resistors connected between a portion of said linear resistors and said first and third electric signal terminals; and

a plurality of comer resistors, connected between said chain resistors and said edge resistors.

16. The touch panel according to claim 1, wherein an active region is created spanning the edge resistors of the second and fourth edge portions.

11. An apparatus for locating a selected touch point physically touched by a human finger or a stylus and producing an electrical signal corresponding thereto, comprising:

an insulating substrate;

a resistor touch pattern supported on the insulating substrate, the resistive touch pattern having;

a plurality of strip resistors parallel to a center line defined by the plurality of strip resistors, each having two ends;

a plurality of linear resistors having first and second ends, each first ends connected respectively to one of the two ends of each of the plurality of strip resistors, resistances of every two linear resistor connected to the two ends of a single one of the plurality of strip resistor being equal, the resistance of the linear resistors decreasing with distance from the center line, a distance between the first and second ends of each linear resistance being equal;

first and second chain resistors connected to each of the second ends of the plurality of the linear resistors, each of the chain resistors having a first portion disposed perpendicular to the strip resistors and second and third portions elongated from both ends of the first portion in an opposing direction and parallel to the strip resistors;

first and second edge resistors parallel to each other and connected to corresponding second and third portions of the chain resistors, each having the same length as the strip resistors;

first and third terminals, respectively, positioned on an intermediate point of each first portion of the first and second chain resistors, each of the first and third terminals connected to a drive circuit and driven at a same time; and

second and fourth terminals, respectively, positioned on an intermediate point of each of the edge resistors, each of the second and fourth terminals connected to the drive circuit and driven at a same time to create an active region defined between the edge resistors of the second and fourth terminals; and

a protective insulating plate arranged over the resistive touch pattern,

wherein the first and third terminals and the second and fourth terminals are driven by the drive circuit alternatively.

12. The apparatus of claim 11, further comprising:

a transparent conductive plate arranged between the substrate and the protective insulating plate; and

dot spacers located between the resistive pattern and the transparent conductive plate, wherein the transparent conductive plate has a low-resistive metal film surrounding edge of the transparent conductive plate and a lead line for outputting an electrical signal representing a location of the stylus or the finger.

13. A touch panel for sensing a point of contact on a display, comprising:

a plurality of strip resistors parallel to one another;

first, second, third and fourth electric signal terminals, the first and third terminals positioned on the midpoint of opposite edges of the touch panel and the second and fourth terminals positioned on the midpoint of opposite edges of the touch panel to create an active region defined between the second and fourth terminals; and

a respective linear resistor connected between a respective end of corresponding strip resistor and at least one of said electric signal terminals, each linear resistor having a resistive value matched to said corresponding strip resistor so as to produce equal potential at a corresponding selected point on substantially all said strip resistors.

14. An apparatus for sensing a physical point of contact on a surface and producing an electrical signal corresponding thereto, comprising:

an insulating substrate

a touch panel having a plurality of strip resistors parallel to one another;

first, second, third and fourth electric signal terminals, the first and third terminals positioned on the midpoint of opposite edges of the touch panel and the second and fourth terminals positioned on the midpoint of opposite edges of the touch panel to create an active region defined between the second and fourth terminals;

a respective linear resistor connected between a respective end of corresponding strip resistor and at least one of said electric signal terminals, each linear resistor having a resistive value matched to said corresponding strip resistor so as to produce equal potential at a corresponding selected point on substantially all said strip resistors; and

a protective insulating plate arranged on the touch panel.

15. The apparatus of claim 14, further comprising:

a transparent conductive plate between the substrate and the protective insulating plate; and

dot spacers between the touch panel and the transparent conductive plate; and

a lead line connected to said transparent conductive plate for conveying electrical signals from the conductive plate when the conductive plate is depressed to be in contact with the touch panel.

17. A touch panel for sensing a point contacted on a display within a active region, comprising:

a plurality of strip resistors parallel to one another, each strip resistor having first and second ends;

a plurality of electric signal terminals, first and third of said electric signal terminals located, respectively, on first and third edge portions of the touch panel, and second and fourth of said electric signal terminals located, respectively, on second and fourth edge portions of the touch panel, wherein each of said electric signal terminals is located at a midpoint of its respective edge portion; and

at least one pair of edge resistors parallel to one another, each individual edge resistor of the at least one pair placed along the second and fourth edge portions of the touch pad to create the active region defined between the second and fourth terminals.