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

• US 9,357,045 B2
• Filed: 03/15/2013
• Issued: 05/31/2016
• Est. Priority Date: 03/19/2012
• Status: Active Grant

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: Oishi, Yuki, Yamashiro, Yo
• Primary Examiner(s): Yang, Kwang-Su
• Application Number:
  US13/839,844
• Publication Number:
  US 20130244731A1
• Time in Patent Office: 1,173 Days
• Field of Search: 345/173, 345/174
• US Class Current: 1/1
• 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 1/0266 for a display module assembly
• CPC Class Codes: H04M 1/23 Construction or mounting of dials or of equivalent devices; Means for facilitating the use thereof by improving visibility H04M1/22
• CPC Class Codes: H04M 1/72454 according to context-related or environment-related conditions
• 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. Further, 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 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 and the same transmission signal is applied to a plurality of transmitter electrodes belonging 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 an operation mode of the transmitter 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 and the same transmission signal is applied to a plurality of transmitter electrodes belonging to the same group, and

wherein the controller switches between a first condition, where the transmitter circuit is fixedly set to the first mode in which one frame is scanned at a first predetermined time interval, and a second condition, where the transmitter circuit is set to alternate between the first mode and the second mode in which one frame is scanned at a second predetermined time interval, and a first repetition period in the first condition is shorter than a second repetition period in the second condition.

2. The control circuit of claim 1, wherein the transmitter circuit is set to the first mode when the electrostatic capacitive sensor is operated as a touch panel, and is set to the second mode when the electrostatic capacitive sensor is operated as a proximity sensor.

3. The control circuit of claim 1, wherein the transmitter circuit is configured such that the number of groups can be changed in the second mode.

4. The control circuit of claim 1, wherein the second predetermined time interval is shorter than the first predetermined time interval.

5. The control circuit of claim 1, wherein the receiver circuit is configured to switch between the 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 the second mode, where the plurality of receiver electrodes are grouped and a plurality of receiver electrodes belonging to the same group is connected in common to generate the detection signal for each group.

6. The control circuit of claim 5, wherein the receiver circuit is configured such that the number of groups can be changed in the second mode.

7. The control circuit of claim 5, further comprising:

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

8. An electronic equipment comprising:

a housing;

a display panel disposed on one surface of the housing;

an electrostatic capacitive sensor disposed at an overlapping portion of the housing with the display panel, the 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 of claim 1, which is disposed within the housing and detects a change in capacitance of the electrostatic capacitive sensor; and

a processor configured to receive a digital value corresponding to the detection signal generated by the receiver circuit of the control circuit and detects a manipulation status of the electronic equipment by a user based on the digital value.

9. The electronic equipment of claim 8, wherein the electronic equipment is a mobile phone further comprising a speaker disposed at a position close to a user'"'"' ear when calling, and

wherein the processor refers to the digital value obtained in the second mode and determines that the user approaches the housing to the user'"'"' head for calling if a change in capacitance formed by the transmitter and the receiver electrodes disposed in the vicinity of the speaker increases.

10. The electronic equipment of claim 8, wherein the processor refers to the digital value obtained in the second mode and determines that a user grips the housing if a change in capacitance of the transmitter and the receiver electrodes disposed at one end of the housing to which the user'"'"' thumb approaches when the housing is gripped by the user and the transmitter and the receiver electrodes disposed at the other end of the housing to which the other fingers approach increase.