Capacitive sensor-based input device

• US 6,781,577 B2
• Filed: 07/03/2001
• Issued: 08/24/2004
• Est. Priority Date: 07/04/2000
• Status: Active Grant

• Current Assignee: Alps Alpine Co., Ltd.
• Original Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Inventors: Shigetaka, Hiroshi
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): LESPERANCE, JEAN E
• Application Number:
  US09/898,508
• Publication Number:
  US 20020039092A1
• Time in Patent Office: 1,148 Days
• Field of Search: 345/173, 345/174-178, 178/18-1-, 178/18.09, 178/18.11
• US Class Current: 345/173
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• 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 sensor-based input device for coordinate data input includes an input unit that detects the variation of capacitances at a plurality of detection points, and a control unit that calculates detection outputs from the plurality of detection points to detect the peak position in the variation of capacitances to generate coordinate data. When the maximum value detected at any one of the detection points transitions relative to the previous and following values by less than a first threshold value, the coordinate data is cancelled. When it varies by more than the first threshold value but less than a second threshold value, a corrected value to generate the coordinate data is decreased, thereby suppressing an oscillation of a cursor on a screen while a finger rests on the input device.

Claims

1. An input device comprising:

an input mechanism to detect a variation of capacitances at a plurality of detection points; and

a control unit to calculate detection outputs from the plurality of detection points to determine a peak position in the variation of capacitances and to generate coordinate data from the peak position,

wherein the peak position is determined using a maximum value detected at any one of the detection points, a previous value detected at at least one previous point to the detection point at which the maximum value is obtained, and a following value detected at at least one point which follows the detection point at which the maximum value is obtained, and said control unit outputs the coordinate data only when a variation of the maximum value varies from the previous value and the following value is greater than a first threshold value.

6. An input device according to claim 1, wherein the value calculated from (2B−

A−

C) is compared to the threshold value, where B denotes the maximum value at any one of the detection points, A denotes the previous value, and C denotes the following value.

7. An input device according to claim 1, wherein the coordinate of the peak position P is defined by the following equation:

$P=\left(\mathrm{coordinate}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{of}<br><br>\text{\hspace{1em}<br><br>}<br><br>B\right)-\frac{A-C}{2<br><br>\left(2<br><br>B-A-C\right)}$

where B denotes the maximum value at any one of the detection points, A denotes the previous value, and C denotes the following value.

2. An input device comprising:

an input mechanism to detect the variation of capacitances at a plurality of detection points; and

a control unit to calculate detection outputs from the plurality of detection points to determine a peak position P in the variation of capacitances and to generate coordinate data at a fixed time interval from the peak position,

wherein said control unit performs a first correction between the peak position, determined at a given point, and coordinate data M obtained at a previous point such that a corrected value is added to the coordinate data, the corrected value being smaller than the peak position minus the coordinate data, and

said control unit;

performs the calculation using a maximum value detected at any one of the detection points, a previous value detected at at least one previous point to the detection point at which the maximum value is generated, and a following value detected at at least one point which follows the detection point at which the maximum value is generated, the first correction used when a variation of the maximum value from the previous value and the following value is less than a threshold value being smaller than when the variation is not less than the threshold value.

3. An input device according to claim 2, wherein the first correction is performed when a displacement of the peak position is within a predetermined distance.

4. An input device according to claim 2, wherein the corrected value is calculated by subtracting (Mn−

1) from a function of Pn and by dividing a resulting value by a predetermined integer m, where Pn indicates the peak position determined at a given time, and (Mn−

1) indicates coordinate data determined at a previous time.

5. An input device according to claim 4, wherein a second correction is performed, prior to the first correction, using the integer m as a predetermined value when a displacement of the peak value is within a predetermined distance, the displacement of the peak being determined at constant time intervals, and the first correction uses one of the same integer m and a different integer.

8. An input device according to claim 2, wherein the value calculated from (2B−

A−

C) is compared to the threshold value, where B denotes the maximum value at any one of the detection points Ni, A denotes the previous value, and C denotes the following value.

9. An input device according to claim 2, wherein a coordinate of the peak position P is defined by the following equation:

$P=\left(\mathrm{coordinate}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{of}<br><br>\text{\hspace{1em}<br><br>}<br><br>B\right)-\frac{A-C}{2<br><br>\left(2<br><br>B-A-C\right)}$

where B denotes the maximum value at any one of the detection points, A denotes the previous value, and C denotes the following value.

10. An input device comprising:

an input mechanism to detect a variation of capacitances at a plurality of detection points; and

a control unit to calculate detection outputs from the plurality of detection points to determine a peak position using the variation of capacitances and to generate coordinate data from the peak position,

the control unit;

determining the peak position at a plurality of times that are each separated by a constant time interval and by using a maximum value detected at any one of the detection points, a previous value detected at a first point adjacent to the detection point at which the maximum value is obtained, and a following value detected at a second point adjacent to the detection point at which the maximum value is obtained,

transmitting the coordinate data only when a combination of a difference between the maximum value and the previous value plus a difference between the maximum value and the following value is greater than a first threshold value, and

performing a first correction to a first peak position determined at;

one time in conjunction with a second peak position determined at a succeeding time to generate coordinate data at the succeeding time, coordinate data being generated such that a first corrected value that is smaller than the second peak position minus the first peak position is added to the first peak position, the first correction being applied only when the combination is less than a second threshold value.

11. An input device according to claim 10, the first correction being performed only when a displacement of the peak position is within a predetermined distance.

12. An input device comprising:

an input mechanism to detect a variation of capacitances at a plurality of detection points; and

a control unit to calculate detection outputs from the plurality of detection points to determine a peak position using the variation of capacitances and to generate coordinate data from the peak position,

the control unit;

determining the peak position at a plurality of times that are each separated by a constant time interval and by using a maximum value detected at any one of the detection points, a previous value detected at a first point adjacent to the detection point at which the maximum value is obtained, and a following value detected at a second point adjacent to the detection point at which the maximum value is obtained,

transmitting the coordinate data only when a combination of a difference between the maximum value and the previous value plus a difference between the maximum value and the following value is greater than a first threshold value, and

performing a first correction and a second correction to a first peak position determined at one time in conjunction with a second peak position determined at a succeeding time to generate coordinate data at the succeeding time, coordinate data being generated such that a first corrected value and a second corrected value that are smaller than the second peak position minus the first peak position are added to the first peak position, the second corrected value dependent on whether a displacement of the peak position is within a predetermined distance.

13. An input device according to claim 12, the control unit performing a third correction only if the combination is less than a second threshold value and when the displacement is within the predetermined distance, the third correction being smaller than the second peak position minus the first peak position.

14. An input device according to claim 12, the second corrected value when the displacement is within the predetermined distance being smaller than the second corrected value when the displacement is not within the predetermined distance.

15. An input device according to claim 13, the second corrected value when the displacement is within the predetermined distance added to the third corrected value being smaller than the second corrected value when the displacement is not within the predetermined distance.

16. An input device according to claim 12, each corrected value being calculated by subtracting coordinate data from a function of the second peak position and dividing a resulting value by an integer, the integer for the first corrected value not necessarily being the same as the integer for the second corrected value.

17. An input device according to claim 13, each corrected value being calculated by subtracting coordinate data from a function of the second peak position and dividing a resulting value by an integer, the integer for the each corrected value not necessarily being the same.

18. An input device according to claim 12, the peak position P being defined by the following equation:

$P=\left(\mathrm{coordinate}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{of}<br><br>\text{\hspace{1em}<br><br>}<br><br>B\right)-\frac{A-C}{2<br><br>\left(2<br><br>B-A-C\right)}$

where B denotes the maximum value at any one of the detection points, A denotes the previous value, and C denotes the following value.

19. A method of decreasing oscillations of a cursor on a screen, the method comprising:

acquiring data at constant times from variations in capacitance at different locations on an input device;

determining a maximum data value at a particular location, previous and following values detected at adjacent locations to the location of the maximum value;

calculating a present peak position of the data;

calculating a combination of a difference between the maximum value and the previous value plus a difference between the maximum value and the following value;

determining whether the combination is greater than a first threshold value;

correcting each present peak position by adding a difference between the present peak position and a function of a previously determined peak position to the previously determined peak position only when the combination is greater than the first threshold value;

determining whether the present peak position is within a predetermined distance from the previous peak position and correcting the present peak position a second time using a correction value dependent thereon;

generating coordinate data from each corrected peak position; and

transmitting the coordinate data.

20. The method of claim 19 further comprising determining whether the combination is less than a second threshold value, and correcting the present peak position a third time only if the combination is less than the second threshold value.

21. The method of claim 19, each correcting comprising correcting by an amount less than the difference between the present peak position and the previously determined peak position.

22. The method of claim 20, each correcting comprising correcting by an amount less than the difference between the present peak position and the previously determined peak position.

23. The method of claim 19, comprising correcting the present peak position by a smaller amount when the displacement is within the predetermined distance than when the displacement is not within the predetermined distance.

24. The method of claim 20, further comprising correcting the present peak position by a smaller amount when the displacement is within the predetermined distance than when the displacement is not within the predetermined distance.

25. The method of claim 19, further comprising correcting the present peak position in each correcting by subtracting coordinate data from a function of the present peak position and by dividing a resulting value by an integer, the integer for the each corrected value not necessarily being the same.

26. The method of claim 20, further comprising correcting the present peak position in each correcting by subtracting coordinate data from a function of the present peak position and by dividing a resulting value by an integer, the integer for the each corrected value not necessarily being the same.

27. The method of claim 19, further comprising calculating each peak position P by:

$P=\left(\mathrm{coordinate}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{of}<br><br>\text{\hspace{1em}<br><br>}<br><br>B\right)-\frac{A-C}{2<br><br>\left(2<br><br>B-A-C\right)}$

where B denotes the maximum value at any one of the detection points, A denotes the previous value, and C denotes the following value.

28. The method of claim 20, further comprising calculating the peak position P by:

$P=\left(\mathrm{coordinate}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{of}<br><br>\text{\hspace{1em}<br><br>}<br><br>B\right)-\frac{A-C}{2<br><br>\left(2<br><br>B-A-C\right)}$

where B denotes the maximum value at any one of the detection points, A denotes the previous value, and C denotes the following value.