Coordinate input device and coordinate calculation method

Abstract

The present invention relates to a coordinate input device and a coordinate calculation method, which calculate the coordinate positions of two objects with high accuracy in each case where the distance between the two objects is relatively long and the distance between the two objects is relatively short. The coordinate input device comprises: a plurality of detection electrodes arranged in a grid shape; a coordinate calculation unit, which calculates the coordinates representing the proximity positions of the objects based on the changes in the electrostatic capacitance of each of the plurality of detection electrodes; and an output unit, which outputs the coordinates calculated by the coordinate calculation unit, wherein the coordinate calculation unit calculates the coordinates by a first calculation method and a second calculation method respectively, and when the two objects are detected by both the first calculation method and the second calculation method, the output unit outputs the coordinates calculated by the first calculation method when the distance between the two objects is greater than a given first threshold value, and outputs the coordinates calculated by the second calculation method when the distance between the two objects is less than a given second threshold value.

Description

Technical Field

[0001] The invention relates to a coordinate input device and a coordinate calculation method. Background Art

[0002] Patent document 1 listed below discloses a technology that detects the contact of an object with a contact surface by an electrostatic capacitance method, detects the distribution area of ​​electrostatic capacitance values ​​exceeding a threshold value, and determines based on the shape of the distribution area whether the object in contact with the contact surface is a single-point touch or a multi-point touch.

[0003] Prior Art Literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2014-186530

[0006] However, in the prior art, when multi-touch is performed between two objects, the coordinate positions of the two objects cannot be calculated with high accuracy in each of the cases where the distance between the two objects is relatively long or relatively short. Summary of the invention

[0007] A coordinate input device according to one embodiment comprises: a plurality of detection electrodes arranged in a grid; a coordinate calculation unit, which calculates coordinates representing a proximity position of an object based on changes in the electrostatic capacitance of each of the plurality of detection electrodes; and an output unit, which outputs the coordinates calculated by the coordinate calculation unit, wherein the coordinate calculation unit calculates the coordinates by a first calculation method and a second calculation method, respectively, wherein in the first calculation method, the coordinates are calculated based on the position of the detection electrode that becomes a peak value of the change in electrostatic capacitance, and in the second calculation method, the coordinates are calculated based on the periodicity of the electrostatic capacitance values ​​on the circumference of a circle with a given radius from the center of gravity of the plurality of detection electrodes that detect the change in electrostatic capacitance, and when two objects are detected by both the first calculation method and the second calculation method, the output unit outputs the coordinates calculated by the first calculation method when the distance between the two objects is greater than a given first threshold value, and outputs the coordinates calculated by the second calculation method when the distance between the two objects is less than a given second threshold value.

[0008] Effects of the Invention

[0009] According to one embodiment, the coordinate positions of each of the two objects can be calculated with high accuracy in each of the cases where the distance between the two objects is relatively long and the case where the distance between the two objects is relatively short. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a block diagram showing the structure of a coordinate input device according to one embodiment.

[0011] Figure 2 This is a block diagram showing a functional structure of a control device according to one embodiment.

[0012] Figure 3 It is a diagram showing an example of calculation of coordinates by a control device (coordinate calculation unit) according to one embodiment.

[0013] Figure 4 This is a diagram showing the relationship between operation input and change in electrostatic capacitance in a coordinate input device according to one embodiment.

[0014] Figure 5 This is a diagram showing the relationship between operation input and change in electrostatic capacitance in a coordinate input device according to one embodiment.

[0015] Figure 6 is a flowchart showing the steps of processing by a control device according to one embodiment.

[0016] Figure 7 It is a diagram showing an output mode of a control device (output unit) according to one embodiment.

[0017] Figure 8 This is a flowchart showing a modified example of the procedure of the process of the control device according to one embodiment.

[0018] Fig. 9 It is a diagram showing a modification example of the output pattern of the control device (output unit) according to one embodiment.

[0019] Fig.10 This is a diagram showing a comparative example of the effects of the coordinate input device according to one embodiment.

[0020] Description of Reference Numerals

[0021] 10: Coordinate input device

[0022] 10A: Operation surface

[0023] 11: Sensor substrate

[0024] 12: X-axis electrode

[0025] 13: Y-axis electrode

[0026] 14: X-axis side detection unit

[0027] 15: Y-axis side detection unit

[0028] 16: A / D conversion unit

[0029] 17: Storage

[0030] 19: Interface

[0031] 20: Control device

[0032] 21: Electrostatic capacitance calculation department

[0033] 22: Coordinate calculation unit

[0034] 23: Output section

[0035] 30, 30A, 30B: Fingers DETAILED DESCRIPTION

[0036] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

[0037] Figure 1 It is a block diagram showing the structure of the coordinate input device 10 according to one embodiment. Figure 1 The coordinate input device 10 shown in the figure is a device that enables an operator's finger 30 (an example of an "object") to move an operation surface 10A (see Figure 3 ) is a device that can detect the proximity position of the operator's finger 30 relative to the operation surface 10A by electrostatic capacitance (self-capacitance detection method or mutual capacitance detection method).

[0038] like Figure 1 As shown, the coordinate input device 10 includes a sensor substrate 11 , an X-axis side detection unit 14 , a Y-axis side detection unit 15 , an A / D conversion unit 16 , a storage unit 17 , a control device 20 , and an interface unit 19 .

[0039] The sensor substrate 11 is arranged on the back side of the operation surface 10A in a stacked manner. The sensor substrate 11 is arranged in a matrix: Figure 1 A plurality of X-axis electrodes 12 arranged side by side in the X-axis direction to detect the electrostatic capacitance in the lateral direction of the Y-axis direction ( Figure 1 A plurality of Y-axis electrodes 13 are arranged side by side in the Y-axis direction to enhance the electrostatic capacitance (in the longitudinal direction) of the electrode.

[0040] The X-axis side detection unit 14 detects the electrostatic capacitance of each of the plurality of X-axis electrodes 12. In addition, the X-axis side detection unit 14 outputs a detection signal (analog signal) indicating the detected electrostatic capacitance of each of the plurality of X-axis electrodes 12.

[0041] The Y-axis side detection unit 15 detects the electrostatic capacitance of each of the plurality of Y-axis electrodes 13. In addition, the Y-axis side detection unit 15 outputs a detection signal (analog signal) indicating the electrostatic capacitance of each of the plurality of Y-axis electrodes 13 that has been detected.

[0042] The A / D (analog / digital) converter 16 converts the detection signal output from the X-axis side detector 14 and the detection signal output from the Y-axis side detector 15 into digital signals, and supplies them to the control device 20 .

[0043] The storage unit 17 stores various information. Examples of the information stored in the storage unit 17 include the electrostatic capacitance value of each of the plurality of X-axis electrodes 12 detected by the X-axis side detection unit 14, the electrostatic capacitance value of each of the plurality of Y-axis electrodes 13 detected by the Y-axis side detection unit 15, and a program executed by the control device 20.

[0044] The control device 20 detects the proximity position of the operator's finger 30 in the operation surface 10A in the X-axis direction based on the change in the electrostatic capacitance of each of the multiple X-axis electrodes 12 determined by the detection signal supplied from the X-axis side detection unit 14 via the A / D conversion unit 16. In addition, the control device 20 detects the proximity position of the operator's finger 30 in the Y-axis direction in the operation surface 10A based on the change in the electrostatic capacitance of each of the multiple Y-axis electrodes 13 determined by the detection signal supplied from the Y-axis side detection unit 15 via the A / D conversion unit 16. Then, the control device 20 outputs coordinate information representing the determined proximity position of the operator's finger 30 (X-axis coordinate and Y-axis coordinate). In addition, for details of the functions of the control device 20, use Figure 2 This will be described later.

[0045] The interface unit 19 outputs the coordinate information indicating the proximity position of the operator's finger 30 output from the control device 20 to an external device (not shown). For example, the external device performs a predetermined process corresponding to the coordinates based on the coordinate information indicating the proximity position of the finger 30 output from the interface unit 19.

[0046] (Functional Structure of Control Device 20)

[0047] Figure 2 2 is a block diagram showing the functional structure of the control device 20 according to one embodiment. Figure 2 As shown, the control device 20 includes an electrostatic capacitance calculation unit 21 , a coordinate calculation unit 22 , and an output unit 23 .

[0048] The electrostatic capacitance calculation unit 21 calculates the amount of change in the electrostatic capacitance of each detection electrode based on the detection signals supplied from the X-axis side detection unit 14 and the Y-axis side detection unit 15 via the A / D conversion unit 16 .

[0049] The coordinate calculation unit 22 calculates coordinates indicating the approach position of the operator's finger 30 on the operation surface 10A in each of the X-axis direction and the Y-axis direction based on the amount of change in the capacitance of each detection electrode detected by the capacitance calculation unit 21 .

[0050] In the present embodiment, the coordinate calculation unit 22 can calculate the coordinates representing the approach position of the operator's finger 30 for the X-axis direction and the Y-axis direction respectively by the vertex calculation method and the period calculation method. The "vertex calculation method" is an example of the "first calculation method". The "vertex calculation method" is a method of calculating coordinates based on the position of the detection electrode that becomes the peak value of the change in electrostatic capacitance. The "period calculation method" is an example of the "second calculation method". The "period calculation method" is a method of periodically calculating coordinates based on the electrostatic capacitance values ​​on the circumference of a circle with a given radius starting from the center of gravity of multiple detection electrodes that detect the change in electrostatic capacitance.

[0051] In addition, in this embodiment, when the operator's two fingers 30 perform an approach operation on the operating surface 10A, the control device 20 can enable the coordinate calculation unit 22 to calculate the coordinates representing the approach positions of the operator's two fingers 30 respectively in the X-axis direction and the Y-axis direction by the vertex calculation method and the period calculation method, respectively.

[0052] The output unit 23 outputs the coordinates detected by the coordinate calculation unit 22 (i.e., the coordinates indicating the approach position of the operator's finger 30). In the present embodiment, when the coordinate calculation unit 22 detects two fingers 30 of the operator in both the vertex calculation method and the period calculation method, the output unit 23 outputs the coordinates calculated by the first calculation method when the distance between the two fingers 30 is greater than a given first threshold value, and outputs the coordinates calculated by the second calculation method when the distance between the two fingers 30 is less than a given second threshold value. In the present embodiment, "22 mm" is used as both the first threshold value and the second threshold value.

[0053] In addition, the control device 20 is configured to include a processor (e.g., CPU), a storage medium (e.g., ROM (Read Only Memory), RAM (Random Access Memory), SSD (Solid State Drive), etc.), a communication interface, etc. as a hardware structure. For example, Figure 2 Each functional unit of the control device 20 shown is implemented by executing a program stored in a storage medium by a processor. In addition, at least one of the A / D converter 16 , the storage unit 17 , and the interface unit 19 may be provided in the control device 20 .

[0054] (Calculation example of coordinates using vertex calculation method)

[0055] Figure 3 It is a diagram showing an example of calculation of coordinates by the control device 20 (coordinate calculation unit 22) according to one embodiment.

[0056] exist Figure 3 In the example shown, 15 X-axis electrodes 12 (X0 to X14) and 15 Y-axis electrodes 13 (Y0 to Y14) are provided in a matrix on the sensor substrate 11 so as to overlap with the operation surface 10A. Figure 3 In the illustrated example, the operator's two fingers 30A and 30B perform a proximity operation on the operation surface 10A.

[0057] like Figure 3 As shown, in the X-axis direction, peak values ​​of the amount of change in electrostatic capacitance are generated at the X-axis electrode X4 overlapping the finger 30A and the X-axis electrode X10 overlapping the finger 30B.

[0058] In addition, if Figure 3 As shown, in the Y-axis direction, peak values ​​of the amount of change in electrostatic capacitance are generated at the Y-axis electrode Y10 overlapping the finger 30A and the Y-axis electrode Y4 overlapping the finger 30B.

[0059] For example, the coordinate calculation unit 22 can calculate the X-axis coordinates of the vertex positions of the quadratic curve C1 passing through the X-axis electrode X4 and the X-axis electrodes X3 and X5 before and after it as the X-axis coordinates indicating the approach position of the finger 30A using a vertex calculation method.

[0060] Similarly, the coordinate calculation unit 22 can calculate the X-axis coordinates of the vertex positions of the quadratic curve C1 passing through the X-axis electrode X10 and the X-axis electrodes X9 and X11 before and after it as the X-axis coordinates indicating the approach position of the finger 30B using the vertex calculation method.

[0061] Similarly, the coordinate calculation unit 22 can calculate the Y-axis coordinates of the vertex positions of the quadratic curve C2 passing through the Y-axis electrode Y10 and the Y-axis electrodes Y9 and Y11 before and after it as the Y-axis coordinates indicating the approach position of the finger 30A using the vertex calculation method.

[0062] Similarly, the coordinate calculation unit 22 can calculate the Y-axis coordinate of the vertex position of the quadratic curve C2 passing through the Y-axis electrode Y4 and the Y-axis electrodes Y3 and Y5 before and after it, as the Y-axis coordinate indicating the approach position of the finger 30B, using the vertex calculation method.

[0063] For example, the coordinate calculation unit 22 can calculate the capacitance change X passing through the peak electrode by using the following equation (1) for each of the X-axis direction and the Y-axis direction, with the electrode having the largest capacitance change being the peak electrode. pk , the change in electrostatic capacitance X in the detection electrode before the peak electrode pk-1 and the change in electrostatic capacitance X in the detection electrode behind the peak electrode pk+1The vertex of the quadratic curve is taken as the coordinate XQ representing the approach position of the operator's finger 30.

[0064] [Formula 1]

[0065]

[0066] In the above formula (1), RESO represents the inter-electrode resolution. OFS represents the coordinates of the peak electrode.

[0067] (Calculation example of coordinates using the period calculation method)

[0068] Below, refer to Figure 4 as well as Figure 5 , an example of coordinate calculation based on the period calculation method of the coordinate calculation unit 22 is described.

[0069] First, the coordinate calculation unit 22 calculates the centroid coordinates based on the change in the electrostatic capacitance of each of the plurality of detection electrodes calculated by the electrostatic capacitance calculation unit 21 .

[0070] Next, the coordinate calculation unit 22 calculates changes in electrostatic capacitance at intersections of the detection electrodes on the circumference of a measurement circle having a given radius and centered on the calculated centroid coordinates.

[0071] Then, the coordinate calculation unit 22 determines whether or not the calculated change in electrostatic capacitance at the intersection of each detection electrode shows a periodicity of two cycles in one turn along the measurement circle.

[0072] When determining that “the periodicity of two cycles is not shown”, the coordinate calculation unit 22 determines that “an input operation by the operator's one finger 30 has been performed” and outputs the centroid coordinates as coordinates indicating the approach position of the operator's one finger 30 .

[0073] On the other hand, when it is determined that “two-cycle periodicity is shown”, the coordinate calculation unit 22 determines that “input operation by two fingers 30 of the operator has been performed”, and calculates and outputs coordinates indicating the respective proximity positions of the two fingers 30 of the operator.

[0074] Figure 4 as well as Figure 5 1 is a diagram showing the relationship between operation input and change in electrostatic capacitance in the coordinate input device 10 according to one embodiment. Figure 4 Indicates Figure 4 As shown in (A), the operation input is performed on the operation surface 10A by one finger 30 of the operator. Figure 5 Indicates Figure 5As shown in (A), the operation input is performed on the operation surface 10A by two fingers 30 of the operator.

[0075] also, Figure 4 (B) and Figure 5 (B) shows the planar distribution of the change in electrostatic capacitance in the operation surface 10A. Figure 4 (B) and Figure 5 In (B), the planar distribution of the change in electrostatic capacitance is shown by the isoline of the change in electrostatic capacitance (solid closed curve). Figure 4 (B) and Figure 5 In (B), a measurement circle having a given radius r is shown by a dotted line. Figure 4 (B) and Figure 5 In (B), the finger area FA, which is the area touched by the operator's finger 30, is shown by a black circle. In the present embodiment, the radius r is set to "9 mm" to match the size of a general finger 30, but the present invention is not limited thereto.

[0076] also, Figure 4 (C) and Figure 5 (C) shows the angular characteristics of the difference value. Figure 4 (C) and Figure 5 In (C), the horizontal axis represents the position on the measurement circle (angle relative to the center of gravity), and the vertical axis represents the change in electrostatic capacitance on the measurement circle.

[0077] For example, Figure 4 As shown in (A), when an operation input is performed by a finger 30 of the operator, as shown in Figure 4 As shown in (B), the finger area FA where the change in electrostatic capacitance exceeds a given threshold value is circular, and the contour lines are also circular. In addition, the centroid that is the center of the measurement circle is the centroid of one finger area FA. In this case, the change in electrostatic capacitance at each sampling point on the measurement circle is equal, so Figure 4 As shown in (C), the angular characteristic of the change in electrostatic capacitance becomes a flat characteristic. Moreover, in this case, the coordinate calculation unit 22 determines that "an input operation based on one finger 30 of the operator has been performed" and outputs the above-mentioned center of gravity coordinates as coordinates representing the proximity position of one finger 30 of the operator.

[0078] In addition, if Figure 5 As shown in (A), when the operator performs an operation input with two fingers 30, as shown in Figure 5As shown in (B), the finger area FA where the change in electrostatic capacitance becomes above a given threshold value is two circles, and the contour lines become ellipses. Regarding the width of the ellipse, it is wide in the direction connecting the two fingers 30 (X direction) and narrow in the direction (Y direction) where they differ by 90 degrees. In addition, the center of gravity, which is the center of the measurement circle, becomes the middle position of the straight line connecting the centers of gravity of the two finger areas FA. In this case, there are two points PMAX in the measurement circle where the change in electrostatic capacitance becomes the largest, so the angular characteristics of the change in electrostatic capacitance are as follows: Figure 5 As shown in (C), a periodicity of two cycles is shown in one cycle along the measurement circle. In this case, the coordinate calculation unit 22 determines that "an input operation based on two fingers 30 of the operator has been performed", and calculates and outputs the coordinates representing the respective proximity positions of the two fingers 30 of the operator.

[0079] For example, the coordinate calculation unit 22 can use a periodic calculation method to obtain the periodicity of the change in electrostatic capacitance in a measuring circle (with a given radius r) through Fourier series expansion, and calculate the coordinates of each of the two fingers 30 based on the distance of each of the two fingers 30 from the center of gravity calculated using the coefficient of the periodicity and the direction of each of the two fingers 30 from the center of gravity (the angle formed by the straight line connecting the two fingers 30 relative to the X-axis) calculated using the phase of the periodicity.

[0080] (Processing steps of the control device 20)

[0081] Figure 6 1 is a flowchart showing the procedure of processing of the control device 20 according to one embodiment.

[0082] First, the capacitance calculation unit 21 calculates the amount of change in capacitance of each detection electrode based on the detection signals supplied from the X-axis detection unit 14 and the Y-axis detection unit 15 via the A / D conversion unit 16 (step S601 ).

[0083] Next, the coordinate calculation unit 22 calculates the coordinates indicating the approach position of the operator's finger 30 by a period calculation method based on the amount of change in the electrostatic capacitance of each detection electrode calculated in step S601 (step S602 ).

[0084] Next, the output unit 23 determines whether two fingers 30 are detected by the cycle calculation method in step S602 (step S603 ).

[0085] In step S603, when it is determined that two fingers 30 are not detected by the period calculation method (step S603: No), the coordinate calculation unit 22 calculates the coordinates representing the approach position of the operator's finger 30 by the vertex calculation method based on the change in the electrostatic capacitance of each detection electrode calculated in step S601 (step S606). Then, the output unit 23 outputs the coordinates calculated by the vertex calculation method in step S606 (step S607). Then, the control device 20 ends. Figure 6 A series of processing is shown.

[0086] On the other hand, in step S603, when it is determined that two fingers 30 are detected by the period calculation method (step S603: Yes), the output unit 23 determines whether the distance between the two coordinates calculated by the period calculation method in step S602 is less than "21 mm" (step S604).

[0087] In step S604, when it is determined that the distance between the two coordinates is not less than "21 mm" (step S604: No), the coordinate calculation unit 22 calculates the coordinates representing the approach position of the operator's finger 30 by the vertex calculation method based on the change in the electrostatic capacitance of each detection electrode calculated in step S601 (step S606). Then, the output unit 23 outputs the coordinates calculated by the vertex calculation method in step S606 (step S607). Then, the control device 20 ends. Figure 6 A series of processing is shown.

[0088] On the other hand, in step S604, when it is determined that the distance between the two coordinates is less than "21 mm" (step S604: Yes), the output unit 23 outputs the coordinates calculated by the period calculation method in step S602 (step S605). Then, the control device 20 ends Figure 6 A series of processing is shown.

[0089] (Output Mode of Output Unit 23)

[0090] Figure 7 It is a diagram showing an output mode of the control device 20 (output unit 23) according to one embodiment. Figure 7 Show Figure 6 The output mode of a series of processed coordinates is shown.

[0091] like Figure 7 As shown, when one finger 30 is detected by the period calculation method, the output unit 23 outputs the coordinates of one or two fingers 30 calculated by the vertex calculation method.

[0092] In addition, if Figure 7As shown, when two fingers 30 are detected by the period calculation method and the distance between the two coordinates calculated by the period calculation method is “21 mm” or more, the output unit 23 outputs the two coordinates calculated by the vertex calculation method.

[0093] On the other hand, Figure 7 As shown, when two fingers 30 are detected by the cycle calculation method and the distance between the two coordinates calculated by the cycle calculation method is less than "21 mm", the output unit 23 outputs the two coordinates calculated by the cycle calculation method.

[0094] In addition, if Figure 7 As shown, when two fingers 30 are detected by the period calculation method and one finger 30 is detected by the vertex detection method, the output unit 23 outputs two coordinates calculated by the period calculation method.

[0095] As described above, a coordinate input device 10 involved in one embodiment comprises: a plurality of detection electrodes arranged in a grid shape; a coordinate calculation unit 22, which calculates the coordinates representing the approach position of the operator's finger 30 based on the change in the electrostatic capacitance of each of the plurality of detection electrodes; and an output unit 23, which outputs the coordinates calculated by the coordinate calculation unit 22, the coordinate calculation unit 22 respectively calculating the coordinates by a vertex calculation method based on the position of the detection electrode that becomes the peak of the change in electrostatic capacitance, and a periodic calculation method based on the periodic calculation of the electrostatic capacitance values ​​on the circumference of a circle with a given radius from the center of gravity of the plurality of detection electrodes that detect the change in electrostatic capacitance, and the output unit 23 outputs the coordinates calculated by the vertex calculation method when two fingers 30 are detected by both the vertex calculation method and the period calculation method, and when the distance between the two fingers 30 is larger than a given first threshold value, the output unit 23 outputs the coordinates calculated by the vertex calculation method, and when the distance between the two fingers 30 is smaller than a given second threshold value, the output unit 23 outputs the coordinates calculated by the period calculation method.

[0096] Thus, the coordinate input device 10 according to one embodiment outputs the coordinates calculated by the vertex calculation method when the distance between the two fingers 30 is relatively long, thereby being able to output high-precision coordinates. In addition, the coordinate input device 10 according to one embodiment outputs the coordinates calculated by the period calculation method when the distance between the two fingers 30 is relatively short, thereby being able to output high-precision coordinates. Therefore, according to the coordinate input device 10 according to one embodiment, the coordinate positions of the two objects can be calculated with high precision in each of the case where the distance between the two objects is relatively long and the case where the distance between the two objects is relatively short.

[0097] In addition, in a coordinate input device 10 involved in one embodiment, when the output unit 23 detects two fingers 30 in both the vertex calculation method and the period calculation method, if the distance between the two fingers 30 detected by the period calculation method is larger than a given first threshold value, the coordinates calculated by the vertex calculation method are output; when the distance between the two fingers 30 detected by the period calculation method is smaller than a given second threshold value, the coordinates calculated by the period calculation method are output.

[0098] Therefore, in a coordinate input device 10 involved in one embodiment, especially when the distance between two fingers 30 is smaller than the second threshold, the period calculation method can calculate the coordinates of the two fingers 30 with higher accuracy than the vertex calculation method, and thus the output coordinates can be determined based on the distance based on the high-precision coordinates calculated by the period calculation method.

[0099] In addition, in a coordinate input device 10 involved in one embodiment, the coordinate calculation unit 22 uses a periodic calculation method to obtain the periodicity of the change in electrostatic capacitance on a measuring circle (given radius r) through Fourier series expansion, and calculates the coordinates of each of the two fingers 30 based on the distance of each of the two fingers 30 from the center of gravity calculated using the coefficients of the periodicity and the directions of each of the two fingers 30 from the center of gravity calculated using the phases of the periodicity.

[0100] Thus, the coordinate input device 10 according to one embodiment can calculate the coordinates of each of the two fingers 30 with high accuracy even when the distance between the two fingers 30 is relatively short.

[0101] In addition, in the coordinate input device 10 involved in one embodiment, the output unit 23 outputs the coordinates calculated by the vertex calculation method when two fingers 30 are not detected by the period calculation method (that is, when one finger 30 is detected by the period calculation method).

[0102] Thus, when a proximity operation is performed by one finger 30 , the coordinate input device 10 according to one embodiment can calculate the coordinates indicating the proximity position of the one finger 30 with high accuracy by using the vertex calculation method.

[0103] In addition, in a coordinate input device 10 involved in one embodiment, the coordinate calculation unit 22 calculates the vertex of a quadratic curve passing through the change in electrostatic capacitance in a peak electrode with the largest change in electrostatic capacitance, the change in electrostatic capacitance in a detection electrode preceding the peak electrode, and the change in electrostatic capacitance in a detection electrode following the peak electrode by a vertex calculation method as the coordinate representing the approach position of the operator's finger 30.

[0104] Thus, the coordinate input device 10 according to one embodiment can calculate the coordinates indicating the approach position of the operator's finger 30 with a resolution higher than the interval between the detection electrodes.

[0105] (Modification of the steps processed by the control device 20)

[0106] Figure 8 It is a flowchart showing a modified example of the procedure of the process of the control device 20 according to one embodiment.

[0107] First, the capacitance calculation unit 21 calculates the amount of change in capacitance of each detection electrode based on the detection signals supplied from the X-axis detection unit 14 and the Y-axis detection unit 15 via the A / D conversion unit 16 (step S801 ).

[0108] Next, the coordinate calculation unit 22 calculates the coordinates indicating the approach position of the operator's finger 30 by a period calculation method based on the amount of change in the electrostatic capacitance of each detection electrode calculated in step S801 (step S802 ).

[0109] Next, the output unit 23 determines whether two fingers 30 are detected by the cycle calculation method in step S802 (step S803 ).

[0110] In step S803, when it is determined that two fingers 30 are detected by the period calculation method (step S803: Yes), the output unit 23 determines whether the distance between the two coordinates calculated by the period calculation method in step S802 is less than "21 mm" (first threshold) (step S804).

[0111] In step S804, when it is determined that the distance between the two coordinates is less than "21 mm" (step S804: Yes), the output unit 23 outputs the coordinates calculated by the period calculation method in step S802 (step S805). Then, the control device 20 returns the process to step S801.

[0112] On the other hand, when it is determined in step S803 that the two fingers 30 are not detected by the period calculation method (step S803: No) and when it is determined in step S804 that the distance between the two coordinates is not less than "21 mm" (step S804: No), the control device 20 causes the processing to enter step S806.

[0113] In step S806, the coordinate calculation unit 22 calculates the coordinates indicating the approach position of the operator's finger 30 by the vertex calculation method based on the change in the electrostatic capacitance of each detection electrode calculated in step 5801 (step S806). Then, the output unit 23 outputs the coordinates calculated by the vertex calculation method in step S806 (step S807).

[0114] Next, the capacitance calculation unit 21 calculates the amount of change in capacitance of each detection electrode based on the detection signals supplied from the X-axis detection unit 14 and the Y-axis detection unit 15 via the A / D conversion unit 16 (step S808 ).

[0115] Next, the coordinate calculation unit 22 calculates the coordinates indicating the approach position of the operator's finger 30 by a period calculation method based on the amount of change in the electrostatic capacitance of each detection electrode calculated in step S808 (step S809 ).

[0116] Next, the output unit 23 determines whether two fingers 30 are detected by the cycle calculation method in step S809 (step S810 ).

[0117] In step S810 , when it is determined that two fingers 30 are not detected by the cycle calculation method (step S810 : No), the control device 20 returns the process to step S806 .

[0118] On the other hand, in step S810, when it is determined that two fingers 30 are detected by the periodic calculation method (step S810: yes), the output unit 23 determines whether the distance between the two coordinates calculated by the periodic calculation method in step S809 is greater than "20 mm" (the second threshold) (step S811).

[0119] In step S811 , when it is determined that the distance between the two coordinates is larger than “20 mm” (step S811 : Yes), the control device 20 returns the process to step S806 .

[0120] On the other hand, in step S811 , when it is determined that the distance between the two coordinates is not greater than “20 mm” (step S811 : No), the control device 20 returns the process to step S805 .

[0121] (Modification of the Output Mode of the Output Unit 23)

[0122] Fig. 9 It is a diagram showing a modification of the output pattern of the control device 20 (output unit 23) according to one embodiment. Fig. 9 Shown based on Figure 8 The output mode of a series of processed coordinates is shown.

[0123] like Fig. 9 As shown, when one finger 30 is detected by the period calculation method, the output unit 23 outputs the coordinates of one or two fingers 30 calculated by the vertex calculation method.

[0124] In addition, if Fig. 9 As shown, when two fingers 30 are detected by the period calculation method and the distance between the two coordinates calculated by the period calculation method is greater than or equal to “21 mm” (first threshold), the output unit 23 outputs the two coordinates calculated by the vertex calculation method.

[0125] On the other hand, Fig. 9 As shown, when two fingers 30 are detected by the cycle calculation method and the distance between the two coordinates calculated by the cycle calculation method is smaller than "20 mm" (second threshold), the output unit 23 outputs the two coordinates calculated by the cycle calculation method.

[0126] In addition, if Fig. 9 As shown, when two fingers 30 are detected by the period calculation method and one finger 30 is detected by the vertex detection method, the output unit 23 outputs two coordinates calculated by the period calculation method.

[0127] In addition, if Fig. 9 As shown, when two fingers 30 are detected by the periodic calculation method and the distance between the two coordinates calculated by the periodic calculation method is greater than "20 mm" (the second threshold value) and less than "21 mm", the output unit 23 outputs two coordinates calculated by the same calculation method as the calculation method used in the calculation of the output coordinates just performed.

[0128] (Comparative example of effect)

[0129] Fig.10 It is a diagram showing a comparative example of the effects obtained by the coordinate input device 10 according to one embodiment. Fig.10 (A) shows Figure 6 The flowchart shown and Figure 7 The output mode shown has the following effects. Fig.10 (B) shows Figure 8 The flowchart shown and Fig. 9 The output mode shown has the following effects.

[0130] exist Fig.10 , an example is shown in which a zoom-in operation is performed to change the zoom-in ratio of an object according to the distance between two fingers 30 on the operation surface 10A using the coordinate input device 10 according to one embodiment. Fig.10 (A) and Fig.10In (B), the vertical axis represents the magnification ratio of the magnification operation, and the horizontal axis represents time. Fig.10 (A) and Fig.10 In (B), the period S1 represents a period in which the distance between the two fingers 30 is fixed to a distance at which the two fingers 30 are in contact with each other (that is, a period in which the enlargement ratio is preferably not changed).

[0131] like Fig.10 As shown in (B), by making the first threshold value different from the second threshold value, Fig.10 Compared with the case where the first threshold value and the second threshold value are made equal as shown in (A) of FIG. 1 , the change in the enlargement ratio of the enlargement operation due to the influence of noise when the distance between the two fingers 30 is fixed to the distance at which the two fingers 30 are in contact with each other can be further suppressed.

[0132] As described above, in a coordinate input device 10 involved in one embodiment, the first threshold value may be larger than the second threshold value, and the output unit 23 may output coordinates calculated by the same calculation method as the calculation method used in the calculation of the output coordinates just performed when the distance between the two fingers 30 is smaller than the first threshold value (in one example, "21 mm") and larger than the second threshold value (in one example, "20 mm").

[0133] Thus, the coordinate input device 10 according to one embodiment can suppress frequent switching of the output coordinate calculation method between the period calculation method and the vertex calculation method when the distance between the two fingers 30 is between the first threshold and the second threshold.

[0134] As mentioned above, although one embodiment of the present invention has been described in detail, the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims.

[0135] For example, in one embodiment, as a vertex calculation method, the coordinate calculation unit 22 calculates the coordinates of the peak position of the change in electrostatic capacitance as the coordinates representing the approach position of the finger 30, but the present invention is not limited thereto. For example, as a vertex calculation method, the coordinate calculation unit 22 may also calculate the coordinates representing the approach position of the finger 30 by regarding the centroid of the region where the change in electrostatic capacitance is greater than a given threshold as the coordinates of the peak position of the change in electrostatic capacitance.

Claims

1. A coordinate input device, characterized in that: have: A plurality of detection electrodes arranged in a grid pattern; a coordinate calculation unit that calculates coordinates indicating a proximity position of an object based on changes in electrostatic capacitance of each of the plurality of detection electrodes; as well as an output unit that outputs the coordinates calculated by the coordinate calculation unit, The coordinate calculation unit calculates the coordinates by a first calculation method and a second calculation method, respectively, wherein in the first calculation method, the coordinates are calculated based on the position of the detection electrode that becomes the peak value of the change in electrostatic capacitance, and in the second calculation method, the coordinates are calculated based on the periodicity of the electrostatic capacitance value on the circumference of a circle with a given radius starting from the center of gravity of a plurality of detection electrodes that detect the change in electrostatic capacitance, The output unit performs the following operations: When two objects are detected by both the first calculation method and the second calculation method, When the distance between the two objects is greater than a given first threshold, outputting the coordinates calculated by the first calculation method, When the distance between the two objects is smaller than a given second threshold, the coordinates calculated by the second calculation method are output.

2. The coordinate input device according to claim 1, characterized in that: The output unit performs the following operations: When two objects are detected by both the first calculation method and the second calculation method, When the distance between the two objects detected by the second calculation method is greater than the given first threshold, outputting the coordinates calculated by the first calculation method, When the distance between the two objects detected by the second calculation method is smaller than the given second threshold value, the coordinates calculated by the second calculation method are output.

3. The coordinate input device according to claim 1 or 2, characterized in that: The coordinate calculation unit calculates the coordinates of each of the two objects using the first calculation method and the second calculation method. In the second calculation method, the periodicity of the change in electrostatic capacitance on the circle with the given radius is obtained by Fourier series expansion, and the coordinates of the two objects are calculated based on the distances of the two objects from the center of gravity calculated using the coefficients of the periodicity and the directions of the two objects from the center of gravity calculated using the phases of the periodicity.

4. The coordinate input device according to claim 1 or 2, characterized in that: The first threshold is greater than the second threshold, The coordinate calculation unit repeatedly calculates the coordinates. When the distance between the two objects is smaller than the first threshold value and larger than the second threshold value, the output unit outputs coordinates calculated using the same calculation method as that used in the calculation of the output coordinates immediately before.

5. The coordinate input device according to claim 1 or 2, characterized in that: The first threshold is equal to the second threshold.

6. The coordinate input device according to claim 1 or 2, characterized in that: The output unit outputs the coordinates calculated by the first calculation method when the two objects are not detected by the second calculation method.

7. The coordinate input device according to claim 1 or 2, characterized in that: The coordinate calculation unit calculates the vertex of a quadratic curve of the change in electrostatic capacitance in the peak electrode with the largest change in electrostatic capacitance, the change in electrostatic capacitance in the detection electrode before the peak electrode, and the change in electrostatic capacitance in the detection electrode after the peak electrode through the first calculation method as coordinates representing the approaching position of the object.

8. The coordinate input device according to claim 1 or 2, characterized in that: The coordinate calculation unit calculates the coordinates by regarding the center of gravity of a range in which the amount of change in the electrostatic capacitance is equal to or greater than a given threshold as a peak position of the amount of change in the electrostatic capacitance.

9. A coordinate calculation method in a coordinate input device having a plurality of detection electrodes arranged in a grid pattern, the coordinate calculation method comprising: a coordinate calculation step of calculating coordinates indicating a proximity position of the object based on changes in the electrostatic capacitance of each of the plurality of detection electrodes; and an output step of outputting the coordinates calculated in the coordinate calculation step, In the coordinate calculation step, the coordinates are calculated by a first calculation method and a second calculation method respectively, wherein: In the first calculation method, the coordinates are calculated based on the position of the detection electrode that becomes the peak value of the change in electrostatic capacitance, and in the second calculation method, the coordinates are calculated based on the periodicity of the electrostatic capacitance value on the circumference of a circle with a given radius starting from the center of gravity of a plurality of detection electrodes that detect the change in electrostatic capacitance, In the output process, When two objects are detected by both the first calculation method and the second calculation method, When the distance between the two objects is greater than a given first threshold, outputting the coordinates calculated by the first calculation method, When the distance between the two objects is smaller than a given second threshold, the coordinates calculated by the second calculation method are output.

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