Input device having capacitance detectors and noise immunity

• US 9,557,721 B2
• Filed: 06/25/2013
• Issued: 01/31/2017
• Est. Priority Date: 08/08/2012
• Status: Active Grant

• Current Assignee: Alps Alpine Co., Ltd.
• Original Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Inventors: Nakajima, Satoshi, Hayasaka, Satoshi, Endo, Shinichi
• Primary Examiner(s): Fennema, Robert
• Assistant Examiner(s): JUNG, JAY YOUNG
• Application Number:
  US13/926,338
• Publication Number:
  US 20140046460A1
• Time in Patent Office: 1,316 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G05B 11/01 electric
• 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

An input device includes a coordinate input unit including capacitance detectors, a capacitance measuring unit that measures the capacitances of the capacitance detectors and outputs them as measurement signals by performing A/D conversion, and a control unit that controls the capacitance measuring unit, obtains the signals while associating them with coordinate information of the capacitance detectors, calculates first data signals that are difference values between the measurement signals and a reference value, performs a calculation for the first data signals, outputs control signals based on the calculation result, performs a first calculation in which the first data signals obtained after performing a noise removal process are associated with the coordinate information as second data signals and a second calculation in which the second signals obtained after performing a smoothing process are associated with the coordinate information as third data signals, and calculates an operation position using the third data signals.

Claims

1. An input device comprising:

a coordinate input unit that includes a plurality of capacitance detectors and on which an operating body performs an operation;

a capacitance measuring unit measuring a capacitance of each of the plurality of capacitance detectors and outputting the capacitance, which has been measured, as a measurement signal by performing an analog-to-digital conversion; and

a control unit controlling the capacitance measuring unit, obtaining the measurement signal while associating the measurement signal with coordinate information of the corresponding capacitance detector, calculating a first data signal that is a difference value between the measurement signal and a reference value, performing a calculation for the first data signal, and outputting a control signal on the basis of a result of the calculation,

wherein the control unit performs a first calculation in which a noise removal process is performed on the first data signal and in which the first data signal, on which the noise removal process has been performed, is associated with the coordinate information as a second data signal, performs a second calculation in which a smoothing process is performed on the second data signal and in which the second data signal, on which the smoothing process has been performed, is associated with the coordinate information as a third data signal, and calculates an operation position using the third data signal,

wherein the noise removal process is performed using the first data signal that is associated with one set of coordinates of interest included in the coordinate information and the first data signals that are associated with a plurality of adjacent coordinates adjacent to the coordinates of interest, and the smoothing process is performed using the second data signal that is associated with the one set of coordinates of interest included in the coordinate information and the second data signals that are associated with the plurality of adjacent coordinates adjacent to the coordinates of interest,

wherein when differences between a difference value that corresponds to the coordinates of interest and each of difference values that correspond to the four adjacent coordinates adjacent to the coordinates of interest, it is determined that the difference value that corresponds to the coordinates of interest includes noise and the average of the difference values that correspond to the four adjacent coordinates is calculated, and the difference value that corresponds to the coordinates of interest is replaced by the average value to perform the noise removal process without performing an accumulation process,

wherein the smoothing process is performed after the noise removal process and is a weighted average process based on a Gaussian function, and

wherein, in the noise removal process, the value of the first data signal that is associated with the coordinates of interest is replaced by the average value of the first data signals that are associated with the plurality of adjacent coordinates when differences between the first data signal that is associated with the coordinates of interest and each of the first data signals that are associated with the plurality of adjacent coordinates become equal to or greater than an abnormal value determination threshold.