Tablet input device

• US 5,266,750 A
• Filed: 05/28/1992
• Issued: 11/30/1993
• Est. Priority Date: 05/30/1991
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Yatsuzuka, Yasufumi
• Primary Examiner(s): Kuntz, Curtis
• Assistant Examiner(s): LOOMIS, PAUL A
• Application Number:
  US07/889,376
• Time in Patent Office: 551 Days
• Field of Search: 178/18, 178/19, 178/20, 178/57, 340/712
• US Class Current: 178/18.05
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact

Abstract

It is so constructed that the current flowing during the input waiting period is reduced. A pull-down resistor is connected to one electrode of X-axis electrodes. A diode is connected to one electrode of Y-axis electrodes along the Y-axis electrode direction. During the input waiting period, the anode terminal of the diode is set to a high level. The detection of the voltage variation of the X-axis electrode to which the resistor is connected is performed during the input waiting period. When the voltage variation is detected, the operation of detecting a position is started.

Claims

1. A tablet input device comprising:

an input tablet having an X-axis tablet in which X-axis electrodes are formed on both sides of an X-axis of a rectangular resistance layer, and a Y-axis tablet in which Y-axis electrodes are formed on both sides of a Y-axis of a rectangular resistance layer, the X-axis tablet and the Y-axis tablet being in a superposed relation;

switching elements respectively connected to the X-axis and Y-axis electrodes;

a pull-down resistor connected to one of the X-axis electrodes;

a diode connected to one of the Y-axis electrodes along the Y-axis electrode direction;

means for, during a waiting period, setting the anode side of the diode to a high level; and

means for, during a waiting period, detecting a voltage variation of the X-axis electrode to which the resistor is connected, and for, when a voltage variation is detected, starting an operation of detecting a position.

3. A tablet input device comprising according to claim 1 wherein:

the position detecting means, during the input waiting period, detects that the input tablet is pressed by detecting a voltage generating across the resistor, the voltage is generated by contacting resistance layers each other by pressing the input tablet and flowing a current toward the resistor through the diode, and starts the operation of detecting the position.

2. A tablet input device comprising:

an input tablet in which an X-axis direction and a Y-axis direction are defined, the X-axis and Y-axis directions being perpendicular to each other, and which has two resistance sheets each having a resistance film formed on a surface, the surfaces of the two resistance sheets facing to each other, a pair of X-axis electrodes being formed on the resistance film at the both sides which are opposed to each other in the X-axis direction of one of the resistance sheets, a pair of Y-axis electrodes being formed on the resistance film at the both sides which are opposed to each other in the Y-axis direction of the other of the resistance sheets;

switching elements respectively connected to the X-axis and Y-axis electrodes;

a pull-down resistor connected to one of the paired electrodes formed on one of the two resistance sheets;

a diode, the cathode of the diode being connected to one of the paired electrodes formed on the resistance sheet to which the resistor is not connected;

means for, during a waiting period, setting the switching elements to be in the OFF state and the anode side of the diode to a high level; and

means for, during the input waiting period, detecting a voltage variation of the electrode to which the resistor is connected, and for, after a voltage variation is detected, starting an operation of detecting a position.

4. A tablet input device comprising according to claim 2 wherein:

the position detecting means, during the input waiting period, detects that the input tablet is pressed by detecting a voltage generating across the resistor, the voltage is generated by contacting resistance layers each other by pressing the input tablet and flowing a current toward the resistor through the diode, and starts the operation of detecting the position. d