Control circuit of electrostatic capacitive sensor and electronic device using the same

• US 9,753,592 B2
• Filed: 06/11/2015
• Issued: 09/05/2017
• Est. Priority Date: 03/19/2012
• Status: Expired due to Fees

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: Oishi, Yuki, Yamashiro, Yo
• Primary Examiner(s): Yang, Kwang-Su
• Application Number:
  US14/736,805
• Publication Number:
  US 20150277631A1
• Time in Patent Office: 817 Days
• Field of Search: 345173, 345174
• CPC Class Codes: G06F 2203/04108 Touchless 2D- digitiser, i.e. digitiser detecting the X/Y position of the input means, finger or stylus, also when it does not touch, but is proximate to the digitiser's interaction surface without distance measurement in the Z direction
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• 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
• CPC Class Codes: H04M 2250/12 including a sensor for measuring a physical value, e.g. temperature or motion telephones including GPS signal receivers H04M2250/10
• CPC Class Codes: H04M 2250/22 including a touch pad, a touch sensor or a touch detector digitizers for touch screens G06F3/041

Abstract

An electrostatic capacitive sensor includes a plurality of transmitter electrodes, a plurality of receiver electrodes, and a control circuit. The control circuit includes: a transmitter circuit configured to apply a periodical transmission signal to each of the plurality of transmitter electrodes; and a receiver circuit configured to generate, based on a reception signal generated in each of the plurality of receiver electrodes in response to the transmission signal, a detection signal indicating a change in electrostatic capacitance formed at each of intersections of the plurality of transmitter electrodes and the plurality of receiver electrodes, wherein the transmitter circuit and the receiver circuit are configured to switch between a first mode and a second mode, in the first mode, the transmission/reception signal is sequentially applied/monitored and in the second mode, the plurality of transmitter/receiver electrodes are grouped so that the same signal is applied to the same group.

Claims

1. A control circuit of an electrostatic capacitive sensor including a plurality of transmitter electrodes disposed in parallel in a first direction and a plurality of receiver electrodes disposed in parallel in a second direction, and spaced apart from the plurality of transmitter electrodes by specific intervals, the control circuit comprising:

a transmitter circuit configured to apply a periodical transmission signal to each of the plurality of transmitter electrodes;

a receiver circuit configured to generate, based on a reception signal generated in each of the plurality of receiver electrodes in response to the transmission signal, a detection signal indicating a change in electrostatic capacitance formed at each of intersections of the plurality of transmitter electrodes and the plurality of receiver electrodes; and

a controller configured to control operation modes of the transmitter circuit and the receiver circuit,

wherein the transmitter circuit is configured to switch between a first mode, where the transmission signal is sequentially applied to the plurality of transmitter electrodes, and a second mode, where the plurality of transmitter electrodes are grouped into one or more groups and the transmission signal is simultaneously applied to transmitter electrodes belonging to the same group,

wherein the receiver circuit is configured to switch between a first mode, where the reception signal generated in each of the plurality of receiver electrodes is sequentially monitored to generate the detection signal for each of the receiver electrodes, and a second mode, where the plurality of receiver electrodes are grouped into one or more groups and receiver electrodes belonging to the same group are connected in common to generate the detection signal for each group, and

wherein the controller switches between a first condition, where the transmitter circuit and the receiver circuit are fixedly set to the first mode, and a second condition, where the transmitter circuit and the receiver circuit are set to alternate between the first mode and the second mode in a time-divisional manner.

2. The control circuit of claim 1, wherein the receiver circuit is configured such that a number of the one or more groups can be changed in the second mode.