Apparatus for detecting an approaching conductor, or an approach point of a conductor and an electrostatic capacity type touch panel apparatus

• US 6,400,359 B1
• Filed: 08/26/1999
• Issued: 06/04/2002
• Est. Priority Date: 08/27/1998
• Status: Expired due to Term

• Current Assignee: Pentel Kabushiki Kaisha
• Original Assignee: Pentel Kabushiki Kaisha
• Inventors: Katabami, Koichiro
• Primary Examiner(s): Shalwala, Bipin
• Assistant Examiner(s): Nguyen, Jimmy H
• Application Number:
  US09/383,653
• Time in Patent Office: 1,013 Days
• Field of Search: 345/173, 345/174, 178/18.01, 178/18.03, 178/18.05, 178/18.08, 178/19.01, 178/20.01, 178/20.03
• US Class Current: 345/173
• CPC Class Codes: G06F 3/0442 using active external devices, e.g. active pens, for transmitting changes in electrical potential to be received by the digitiser

Abstract

There are provided an apparatus for detecting an approaching conductor and an approach point or position of a conductor, in which a signal processing is simply performed and an improvement in the noise resistance is performed without the influence of a floating capacity. The apparatus has a voltage-oscillating system for equivalently receiving electric oscillation (AC signal) from a detected conductor so that the received electric oscillation is processed as a signal to ground and the processed signal is send to a non-oscillating system through an isolator, the system including a sensor panel or a sensor conductive array, a shield plate, a signal processing circuit, a ground, and power source. In addition, in order to clearly and securably identify a cause of the false earth effect of a detected conductor such as a human body, over 200 kHz oscillation frequency is provided. There is also provided an electrostatic capacity coupling type touch panel apparatus, in which an AC signal is applied into a finger, AC signal being 200 or more kHz frequency.

Claims

1. An apparatus for detecting a approach point or position of a conductor on a sensor panel, including a voltage-oscillating system and a non-oscillating system;

said voltage-oscillating system having the sensor panel which is operated by over 200 kHz frequency oscillatory voltage generator so that a AC current flowing through an electrostatic coupling between said sensor panel and said conductor is equivalently received, the sensor panel having a resistor with uniform face resistance in the two-dimensional directions and electrodes closely disposed in the periphery of said resistor, signal processing means on which AC currents from four corners of the sensor panel are impressed, a voltage oscillating system ground circuit to be also connected with the signal processing means, and a power circuit which voltage oscillates in same amplitude and same phase with respect to the voltage oscillating system ground circuit, the power circuit being connected with the signal processing means;

said non-oscillating system having an interface with said voltage oscillating system and at least one or more external apparatus; and

further including an isolator thorough which a digital or an analog electric information is transferred between said signal processing means and said interface.

2. The apparatus for detecting an approach point or position of a conductor defined in claim 1, wherein the ground circuit, the power supply circuit, and a digital or analog electric information wire between said voltage-oscillating system and said non-oscillating system are connected through a multiwire common mode resonant transformer wound around the same closed magnetic path magnetic core.

3. The apparatus for detecting an approach point or position of a conductor defined in claim 2, wherein said multiwire common mode resonant transformer is driven by a C-class operation transistor.

4. The apparatus for detecting an approach point or position of a conductor defined in claim 1, the apparatus further including means for providing a compensation to cause said approach point or position to be deviated from a center position in a peripheral direction, when an AC current having a value smaller than a reference current value is measured, the reference current value being a total value of AC currents flowing from four corners of said sensor panel, when said conductor touches on the sensor panel.

5. An apparatus for detecting an approach position on a position indication means on the surface of a sensor panel including:

at least the sensor panel for receiving AC signal which is actively or equivalently transmitted from said position through an electrostatic coupling, the sensor panel having a resistor with an uniform resistant face in the two-dimensional directions; and

a current/voltage conversion circuit on which AC currents from four corners of the sensor panel are impressed;

the current/voltage conversion circuit including an emitter input transistor to be base-grounded through a resistance, parallel resonant circuit connected to a collector of said transistor LC, and an inverted amplifier for inverting and amplifying a voltage variation of said emitter input to be applied to a base of said transistor.