Touch-panel device

• US 6,816,153 B2
• Filed: 08/03/2001
• Issued: 11/09/2004
• Est. Priority Date: 08/04/2000
• Status: Expired due to Fees

• Current Assignee: Gunze Limited
• Original Assignee: Gunze Limited
• Inventors: Kobayashi, Toshiyuki, Yamada, Tsutomu
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): FATAHI YAR, MAHMOUD
• Application Number:
  US09/920,991
• Publication Number:
  US 20020039094A1
• Time in Patent Office: 1,194 Days
• Field of Search: 345/173, 345/174, 178/18.01, 178/18.03, 178/18.5
• US Class Current: 345/174
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact

Abstract

A touch-panel device including a conductive membrane, current measurement resistors which are connected at one end to both ends of the conductive membrane and which are connected at the other end to one another, an oscillator which is connected on one end to the connection point of the current measurement resistors and is connected on its other end to the ground, and a serial connection circuit of a switch and a load impedance which circuit is connected between the ground side of the oscillator and one end of the conductive membrane. The touch-panel device measures voltages V₁₀ and V₂₀ of both resistors and calculates R_k/R_o=V₂₀/(V₁₀−V₂₀) by turning the switch ON. When a touch position is to be measured, substitute R_k/R_o to the equation of R_L/R_o=R_k(V₂−V₁)/R(V1+V2)+V2/(V1+V2) so as to obtain a touch position. Therefore, touch position detection accuracy is improved and the cost is reduced.

Claims

1. A touch-panel device comprising:

a touch-panel including a substrate and a conductive membrane provided on the substrate;

an AC current generation section for supplying AC currents to the conductive membrane through a first point and a second point which are at outer peripheral sections of the conductive membrane; and

current measurement sections for measuring a first current supplied through the first point and a second current supplied through the second point;

wherein the touch panel has an impedance which is connected by interposing a switch between one end of the AC current generation section and a connection point, and

wherein a touch position on the touch-panel is calculated based upon a current measurement value measured by the current measurement sections when the position measurement is not carried out and when the switch is turned ON and another current measurement value measured by the current measurement sections when the switch is turned OFF.

2. A touch-panel device as set forth in claim 1, wherein the switch is turned ON and turned OFF at constant intervals, a current measurement value measured by the current measurement section when the switch is turned ON is memorized, and a touch position on the touch-panel is calculated based upon the memorized current measurement value and a current measurement value measured by the current measurement section when the switch is turned OFF.

3. A touch panel device comprising:

a touch-panel including a substrate, a conductive membrane provided on the substrate, and electrodes made of low resistance conductive material, the resistance of the electrodes being lower than the resistance of the conductive membrane, said electrodes being provided at peripheral sections of the conductive membrane;

an AC current generation section for supplying AC currents to the conductive membrane through a first point and a second point which are at outer peripheral sections of the conductive membrane; and

current measurement sections for measuring a first current supplied through the first point and a second current supplied though the second point,

wherein a touched position is calculated based upon the measured first current and the measured second current; and

the resistance value of the electrodes is determined to be an optimum value using a calculation formula of;