CAPACITIVE TOUCH SENSING DEVICE BY DETECTING INDUCED ELECTRIC FIELD

• US 20120092028A1
• Filed: 10/18/2011
• Published: 04/19/2012
• Est. Priority Date: 10/19/2010
• Status: Active Grant

• Current Assignee: Invention Element Inc.
• Original Assignee: Invention Element Inc.
• Inventors: LEE, Hsiang-Yu, Lin, Ping-Tsun
• Granted Patent: US 8,773,147 B2
• Time in Patent Office: Days
• US Class Current: 324/658
• CPC Class Codes: G06F 3/04164 Connections between sensors and controllers, e.g. routing lines between electrodes and connection pads
• CPC Class Codes: G06F 3/04182 Filtering of noise external to the device and not generated by digitiser components
• CPC Class Codes: G06F 3/044 by capacitive means
• 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 capacitive touch sensing device by detecting induced electric field includes a differential amplifier, a resistor and a signal judgment circuit. The differential amplifier is electrically connected to a touch sensor. The resistor is electrically connected to a first input end and a second input end of the differential amplifier. The signal judgment circuit is electrically connected to an output end of the differential amplifier. As the touch sensor receives an induced electric field signal, the induced electric field signal is amplified by the differential amplifier and the signal judgment circuit determines whether the amplified induced electric field signal is a touch input.

Claims

1. A capacitive touch sensing device by detecting induced electric field, comprising:

a differential amplifier having a first input end, a second input end and an output end;

a resistor having two ends electrically connected to the first input end and the second input end of the differential amplifier, respectively; and

a signal judgment circuit electrically connected to the output end of the differential amplifier,

wherein the first input end of the differential amplifier is electrically connected to a touch sensor, the second input end of the differential amplifier is connected to circuit ground, and as the touch sensor receives an induced electric field signal, the induced electric field signal is amplified by the differential amplifier and the induced electric field signal after amplification is then determined by the signal judgment circuit.

2. The capacitive touch sensing device by detecting induced electric field as claimed in claim 1, wherein the signal judgment circuit includes:

a peak value sampling circuit electrically connected to the output end of the differential amplifier to proceed with peak value sampling of the amplified induced electric field signal; and

a comparator electrically connected to the peak value sampling circuit for comparing the amplified induced electric field signal after peak value sampling with a reference voltage, in which if the amplified induced electric field signal after peak value sampling is larger than the reference voltage, it output a signal.

3. The capacitive touch sensing device by detecting induced electric field as claimed in claim 1, wherein the signal judgment circuit includes:

a zero potential triggering circuit electrically connected to the output end of the differential amplifier, in which as the amplified induced electric field signal is at a zero potential, the zero potential triggering circuit generates a triggering signal;

a delay circuit electrically connected to the zero potential triggering circuit for correspondingly receiving the triggering signal and delaying the triggering signal a period of time for output; and

a comparator electrically connected to the delay circuit to compare the amplified induced electric field signal with a reference voltage upon receiving the delayed triggering signal from the delay circuit, in which if the amplified induced electric field signal is larger than the reference voltage, it output a signal.

4. The capacitive touch sensing device by detecting induced electric field as claimed in claim 1, wherein the signal judgment circuit includes:

a zero potential triggering circuit electrically connected to the output end of the differential amplifier, in which as the amplified induced electric field signal is at a zero potential, the zero potential triggering circuit generates a triggering signal;

a microcontroller electrically connected to the zero potential triggering circuit for receiving the triggering signal and correspondingly output a delayed triggering signal; and

an analog/digital converter electrically connected to the output end of the differential amplifier and to the microcontroller, in which as the analog/digital converter receives the delayed triggering signal from the microcontroller, the analog/digital converter proceeds with sampling with respect to the amplified induced electric field signal and output a digital value to the microcontroller.

5. The capacitive touch sensing device by detecting induced electric field as claimed in claim 1, further comprising a capacitor electrically connected to the first input end and the second input end of the differential amplifier.

6. The capacitive touch sensing device by detecting induced electric field as claimed in claim 1, wherein the resistor is a high impedance resistor.

7. The capacitive touch sensing device by detecting induced electric field as claimed in claim 1, wherein the touch sensor is a touch sensing button, a slider, a shuttle or a touch panel.

8. The capacitive touch sensing device by detecting induced electric field as claimed in claim 1, wherein the first input end is a positive input end and the second input end is a negative input end.

9. The capacitive touch sensing device by detecting induced electric field as claimed in claim 1, wherein the first input end is a negative input end and the second input end is a positive input end.

10. A capacitive touch sensing device by detecting induced electric field, comprising:

a multiplexer;

a plurality of first conductive wires arranged sequentially along a first direction, each being electrically connected to the multiplexer;

a plurality of second conductive wires arranged sequentially along a second direction, each being electrically connected to the multiplexer;

a differential amplifier electrically connected to the multiplexer; and

a signal judgment circuit electrically connected to the differential amplifier,

wherein the plurality of first conductive wires and the plurality of second conductive wires are electrically connected to the differential amplifier via the multiplexer, and as one of the plurality of first conductive wires and one of the plurality of second conductive wires receive an induced electric field signal, the multiplexer, being connected thereto, transfers the induced electric field signal to the differential amplifier for amplification and the amplified induced electric field signal is determined by the signal judgment circuit.

11. The capacitive touch sensing device by detecting induced electric field as claimed in claim 10, wherein the first direction and the second direction are orthogonal.