COORDINATES INPUT DEVICE

Abstract

In a coordinate input device which is equipped with large sensor electrodes to increase detection sensitivity, the occurrence of position errors is reduced. A coordinate input device comprises sensor electrodes, an upper panel with an operating surface which can be actuated by using an operating body and which covers the sensor electrodes, a measuring circuit which is configured to measure a capacitance at each of a plurality of detection points, and a computation circuit which is configured to calculate a position of the operating body on the operating surface based on the measured capacitance at the plurality of detection points.The calculation circuit calculates, for each of three or more measured values ​​that comprise the maximum value of the majority of measured values ​​obtained at the majority of detection points, a first corrected measured value to reduce differences between the measured values, and calculates the position of the operating body in biaxial directions on the operating surface using the first corrected measured value corresponding to the maximum value and the first corrected measured values ​​corresponding to the measured values ​​adjacent to the maximum value in one of the biaxial directions.

Description

Technical field

[0001] The present disclosure relates to a coordinate input device. background

[0002] A known coordinate input device comprises a plurality of electrodes arranged in a predetermined direction, a detection unit configured to detect the capacitance of each of the plurality of electrodes, and an arithmetic processing unit configured to calculate the coordinates of a detection target using various computation methods based on the state of a variation in the capacitance of the plurality of electrodes. The arithmetic processing unit calculates the coordinates of the detection target using a center-of-gravity calculation method to determine the coordinates of the center of gravity and a curve approximation method to calculate a peak value of a curve based on a comparison between a capacitance variation of a peak electrode and a capacitance variation of an electrode not adjacent to the peak electrode (see, e.g., patent literature 1). Citation list of patent literature

[0003] PTL 1: Japanese unexamined patent application Publication No. 2013-003978 Summary of the invention: Technical problem

[0004] If larger sensor electrodes are used in such a coordinate input device, the detection sensitivity for the operating surface, on which the user performs an operation using an operating body such as a hand or similar, can be increased in a non-contact state. However, in the known method, the larger sensor electrodes can lead to errors in detecting the position of the operating body. Solution to the problem

[0005] Accordingly, the present disclosure was made to reduce such detection errors in coordinate input devices which are equipped with larger electrodes for increased detection sensitivity. Solution to the problem

[0006] A coordinate input device according to one aspect of the disclosure comprises an insulating substrate, sensor electrodes having a plurality of detection points, the sensor electrodes being arranged on the insulating substrate, an upper panel having an operating surface that can be actuated using an operating body, the upper panel covering the sensor electrodes, a measuring circuit configured to measure capacitance at each of the plurality of detection points, and a computation circuit configured to calculate a position of the operating body in two-axis directions on the operating surface based on the capacitance measurements at the plurality of detection points. The computation circuit corrects for each of three or more measurements, which include the maximum value of the plurality of measurements,which were obtained at the majority of detection points, the measured value and calculates a first corrected measured value which is smaller than the measured value, calculates the first corrected measured values ​​such that the differences between the measured values ​​and the first corrected measured values ​​increase non-linearly as the measured values ​​increase, or calculates the first corrected measured values ​​such that the differences between the measured values ​​and the first corrected measured values ​​increase non-linearly or linearly as the measured values ​​become greater than or equal to a predetermined value, and calculates the position of the operating body in the biaxial directions on the operating surface using the first corrected measured value which corresponds to the maximum value, and the first corrected measured values ​​which correspond to the measured values ​​which are adjacent to the maximum value in one of the biaxial directions. Advantageous effects of the invention

[0007] In coordinate input devices which are provided with larger electrodes for increased detection sensitivity, a coordinate input device with reduced detection errors can be provided. Brief description of the drawings [ Fig. 1] Fig. Figure 1 is a diagram of an exemplary structure of an electrostatic coordinate input device according to one embodiment. [ Fig. 2] Fig. Figure 2 is a diagram of an exemplary structure of an electrostatic coordinate input device according to one embodiment. [ Fig. 3] Fig. Figure 3 shows an exemplary structure of an electrostatic sensor and a control device in an electrostatic coordinate input device. [ Fig. 4] Fig. Figure 4 is a diagram of an exemplary state in which an operation is performed with a fingertip of a hand on an operating surface of an electrostatic coordinate input device. [ Fig. 5] Fig. Figure 5 is a diagram of an exemplary relationship between measured values ​​and first corrected measured values. [ Fig. 6A] Fig. Figure 6A is a diagram illustrating an example curve approximation method. [ Fig. 6B] Fig. 6B is a diagram that shows an example of a center of gravity calculation method. [ Fig. 7A] Fig. 7A is a flowchart that shows an example of the processing to be carried out by a computing unit to calculate the position of a fingertip. [ Fig. 7B] Fig. 7B is a flowchart which shows an example of interpolation processing for coordinates in steps S4 and S8 in Fig. 7A is shown. [ Fig. 8] Fig. Figure 8 is a diagram of example simulation results. [ Fig. 9A] Fig. Figure 9A is a diagram of an example variation of the characteristics of the first corrected measured values. [ Fig. 9B] Fig. Figure 9B is a diagram of an exemplary variation of the characteristics of first corrected measurements. [ Fig. 9C] Fig. Figure 9C is a diagram of an exemplary variation in the characteristics of initial corrected measurements. Description of the embodiments.

[0008] The following describes a coordinate input device according to one embodiment of the disclosure. <Ausführungsform>

[0009] Fig. 1 and Fig. Figure 2 shows schematic representations of exemplary structures of a coordinate input device 100 according to the embodiment. Fig. Figure 1 shows the coordinate input device 100 in an operational state and a display device 110 that shows an input image. When the display device 110 shows the input image, the coordinate input device 100 is in an input mode. The input mode is a mode in which an operational input can be made to the coordinate input device 100. The coordinate input device 100 in Fig. Device 2 is in a standby state, and display device 110 shows a standby image. When display device 110 shows the standby image, input device 100 is in a power-saving mode. In standby mode, display device 110 is generally displayed in gray and consumes less power. Fig. Figure 3 is a diagram of example structures of an electrostatic sensor 120 and a control device 130 in the coordinate input device 100. The display device 110 is an example of a display section, the electrostatic sensor 120 is an example of a detection section, and the control device 130 is an example of a control section.

[0010] The following description defines and describes an XYZ coordinate system. A direction (X-direction) parallel to the X-axis, a direction (Y-direction) parallel to the Y-axis, and a direction (Z-direction) parallel to the Z-axis are orthogonal to each other. Furthermore, in the following description, a -Z-direction denotes a direction towards the electrostatic sensor 120, and a +Z-direction denotes a direction away from the electrostatic sensor 120. The phrase "top view" refers to viewing the XY plane. For clarity, the length, width, thickness, and other dimensions of individual components may be exaggerated in the following description.

[0011] The coordinate input device 100 could, for example, be a tablet-like input device or an input unit of an ATM, which are installed in shops or establishments and used by the general public. Alternatively, the coordinate input device 100 could also be an input area of ​​a cooking appliance that needs to be kept clean. Alternatively, the coordinate input device 100 could be a tablet computer, a smartphone, a gaming device, or similar device for personal use. <Gesamtaufbau der Koordinaten Eingabevorrichtung 100>

[0012] The coordinate input device 100 comprises a housing 101, an upper panel 105, the display device 110, the electrostatic sensor 120, and the control device 130. Although the control device 130 (see Fig. 3) in Fig. 1 and Fig. With the omission of 2, the control device 130 is arranged, for example, below the display device 110 and the electrostatic sensor 120 in the housing 101. The coordinate input device 100 includes the one described in Fig. 3 electrostatic sensor 120 and the control device 130 shown. <Gehäuse 101 und oberes Panel 105>

[0013] The housing 101 is a housing made of resin, metal, or the like and is used to accommodate the display device 110, the electrostatic sensor 120, and the control device 130. The display device 110 is, for example, arranged below the transparent electrostatic sensor 120 and is visible through an operating surface 105A, which is an upper surface of the transparent upper panel 105 arranged in an opening section provided on an upper section of the housing 101. <Operationsverfahren der Koordinaten Eingabevorrichtung 100>

[0014] The coordinate input device 100 can be operated either in a non-contact state, in which an operating body, such as a user's hand, is not in contact with the operating surface 105A, or in a contact state, in which an operating body, such as a user's hand, is in contact with the operating surface 105A.

[0015] The operational procedures for the coordinate input device 100 comprise four procedures: a proximity operation, a selection operation, a confirmation operation, and a contact operation. In these four operational procedures, the proximity operation, the selection operation, and the confirmation operation are performed in a contactless state using an operating body, e.g., a hand, on the operating surface 105A. The contact operation is performed in a state in which an operating body, e.g., a hand, is in contact with the operating surface 105A.

[0016] The coordinate input device 100 distinguishes five distance states between an operating body, such as a hand, and the operating surface 105A in order to determine the four operating procedures. These five distance states include an undetected state, a proximity state, a selection state, a confirmation state, and a contact state. The five distance states include a contact state, in which an operating body, e.g., a hand, is in contact with the operating surface 105A, and a non-contact state, in which an operating body, e.g., a hand, is not in contact with the operating surface 105A. The undetected state, the proximity state, the selection state, and the confirmation state are the non-contact states.

[0017] The undetected state refers to a state in which no proximity operation, selection operation, confirmation operation, or contact operation is performed. The proximity state, selection state, confirmation state, and contact state refer to states in which the proximity operation, selection operation, confirmation operation, and contact operation, respectively, are performed. The coordinate input device 100 uses a plurality of electrostatic capacitance thresholds to determine the operational procedures. As the states change from the contact state through the confirmation state, selection state, proximity state, and finally to the undetected state, the positions of an operating body, such as a hand, move away from the operating surface 105A.

[0018] The coordinate input device 100 is a device that is operated by the user by performing a pointing operation. The pointing operation is an operation performed by holding a finger approximately perpendicular to the operating surface 105A. More than one finger can be used in the pointing operation, but preferably only one finger.

[0019] When performing such a pointing operation, if the finger is not approximately perpendicular to the operating surface 105A, the entire palm of the hand approaches the operating surface 105A, and the distribution of the capacity detected by the coordinate input device 100 changes significantly. Accordingly, the coordinate input device 100 determines whether a pointing operation is performed appropriately.

[0020] In the following description, an operation in which a pointing operation is performed inappropriately, typically with the entire palm, is referred to as a non-pointing operation. The coordinate input device 100 determines, based on the capacity distribution, whether the user's operation is a pointing or a non-pointing operation. If the operation is a non-pointing operation, the calculation of the fingertip position (FT) may be omitted, and a warning may be displayed indicating that it is a non-pointing operation. Alternatively, the calculation of the fingertip position (FT) may be performed, and a warning may be displayed indicating that the operation is a non-pointing operation.

[0021] In the following description, the user performs an operation using hand H as an example of the operating body. Furthermore, in the following description, performing a proximity operation, a selection operation, a confirmation operation, or a contact operation with hand H is simply referred to as performing an operation (proximity operation, selection operation, confirmation operation, or contact operation) with hand H.

[0022] The approximation operation refers to an operation in which the hand H is moved towards the operating surface 105A of the coordinate input device 100 without touching the operating surface 105A, and is an operation for switching the coordinate input device 100 from the one in Fig. 2 standby state shown in the in Fig. 1 depicted operational state.

[0023] The selection operation refers to an operation in which the hand H is moved from the state in which the approach operation is performed, without touching the operation surface 105A, further in the direction of the operation surface 105A of the coordinates input device 100 in order to select a GUI button displayed on the display device 110.

[0024] The confirmation operation refers to a process in which hand H, from the state in which the selection operation is performed, is moved further towards the operating surface 105A of the coordinate input device 100 without touching it, in order to fix the operation input at the selected GUI button. The confirmation operation is an operation for performing a contactless operation input and is an operation to operate the coordinate input device 100 in a contactless manner without touching the operating surface 105A with hand H. An operation input that is performed contactlessly using the selection operation and the confirmation operation can also be referred to as a floating input or contactless input.

[0025] The contact operation refers to a process in which the hand H is moved from the state in which the selection operation is performed further towards the operating surface 105A of the coordinate input device 100 in order to touch the operating surface 105A and thus fix the operational input on the selected GUI button. The contact operation can be described as a touch input. <Anzeigevorrichtung 110>

[0026] The display device 110 is, for example, a liquid crystal display, an organic electroluminescent (EL) display, or the like. The display device 110 is a display for implementing a graphical user interface (GUI). The display device 110 shows images of GUI buttons 111, a cursor, and an image of an input content display section 115, which displays input content. The GUI buttons 111 are an example of an operation section and are, for example, arranged in a matrix state in the top view. Each of the GUI buttons 111 has, for example, a round shape resembling a push button.

[0027] Fig. 1 to Fig. Figure 3 shows an example of a total of 45 GUI keys 111, comprising 26 alphabetic GUI keys 111, 15 GUI keys 111 in the form of a numeric keypad, and 4 GUI keys 111, including a menu key (three-row key in the upper left), a Caps Lock key, a backspace key (upper right), and an Enter key (lower right). The 45 GUI keys 111 are arranged in 5 columns in the Y direction and 11 rows in the X direction. The rows extend in the X direction, and the Y direction extends in a column direction. It should be noted that the GUI keys 111 are not limited to alphabetic characters, numeric keypad numbers, or similar, but can also be characters, symbols, or similar in other languages.

[0028] Here, an example of a total of 45 GUI keys 111 is described, which are displayed by means of the display device 110. The coordinate input device 100 can, however, also include the upper panel 105 with an operation unit on which alphabetic characters, numbers, symbols, or the like are printed instead of all or at least some of the 45 GUI keys 111. For example, a backlight can be arranged on the rear of the upper panel 105 so that light can pass through the operation unit on which alphabetic characters, numbers, symbols, or the like are printed.When the coordinate input device 100 is in standby mode, the backlight can be switched off, and when the coordinate input device 100 is switched to input mode, the backlight can be switched on to illuminate the alphabetic characters, numbers, symbols, or the like printed on the operating unit of the upper panel 105. In such a case, a liquid crystal display, an organic EL display, or the like can be provided for displaying input content only in the portion of the input content display section 115. <Elektrostatischer Sensor 120>

[0029] The electrostatic sensor 120 is arranged on the display device 110 and comprises a plurality of sensor electrodes 121X extending in the X direction and a plurality of sensor electrodes 121Y extending in the Y direction, as shown in Fig. Figure 3 illustrates this. The sensor electrodes 121X and 121Y are examples of electrodes in the detection section and are connected to the device 130 via wires 122X and 122Y, respectively. The sensor electrodes 121X and 121Y are formed on an insulating substrate 125. Such an electrostatic sensor 120 can be produced by forming a transparent conductive film, such as an indium tin oxide (ITO) film, on the surface of a transparent glass substrate and structuring the film as sensor electrodes 121X and 121Y and as wires 122X and 122Y. The capacitance detected by the electrostatic sensor 120 is input to the device 130. The capacitance detected by the electrostatic sensor 120 is an example of a detection result of the electrostatic sensor 120.

[0030] Fig. Figure 3 shows, as an example, a plurality of sensor electrodes 121X and a plurality of sensor electrodes 121Y. The distance between the sensor electrodes 121X and the distance between the sensor electrodes 121Y corresponds approximately to an average width (approx. 10 mm) of the human fingertips and approximately to the distance between the GUI buttons 111.

[0031] The majority of sensor electrodes 121X are sampled in a row, and the majority of sensor electrodes 121Y are sampled in a column. An analog-to-digital converter (ADC) unit 132 converts the capacitance at a majority of intersection points of the majority of sensor electrodes 121X and the majority of sensor electrodes 121Y into digital values. A counter 133 counts a change in the output of the ADC unit 132 and outputs a difference value ΔAD at each intersection point. Each intersection point is an example of a detection point. It should be noted that the GUI buttons 111 and the sensor electrodes, which are approximately the same size as the GUI buttons 111, can be provided in a one-to-one correspondence.

[0032] The position of hand H, represented by XY coordinates and detected by the coordinate input device 100 using the electrostatic sensor 120, is, for example, the XY coordinate at which the capacitance is greatest in the region where hand H is located. The position of hand H in the Z-direction, detected by the coordinate input device 100 using the electrostatic sensor 120, is inversely proportional to the capacitance detected by the electrostatic sensor 120, so that determining the position of hand H in the Z-direction is equivalent to determining the capacitance between hand H and the electrostatic sensor 120.The coordinate input device 100 determines, for example, the position of hand H in the Z direction based on the capacitance between hand H and the electrostatic sensor 120; however, in the following description, where it is easier to understand to describe the position of hand H in the Z direction, this will be described as the position of hand H in the Z direction. <Steuervorrichtung 130>

[0033] The control device 130 is implemented by means of a computer which includes a central processing unit (CPU), a random access memory (RAM), a read-only memory (ROM), an input / output interface, an internal bus and the like.

[0034] The control device 130 comprises a main control unit 131, an analog-to-digital (AD) converter unit 132, a counter 133, a processing unit 134, an operational control unit 135, a display control unit 136, and a memory 137. The ADC unit 132 and the counter 133 are examples of a measuring circuit. The processing unit 134 is an example of a computational circuit. The main control unit 131, the ADC unit 132, the counter 133, the processing unit 134, the operational control unit 135, and the display control unit 136 represent functions of a program to be implemented by means of the control device 130 as function blocks. The memory 137 represents the function of the memory of the control device 130.

[0035] The main control unit 131 is a processing unit that performs overall control of the processing in the control device 130 and carries out processing operations other than those performed by the A / D converter unit 132, the counter 133, the computation unit 134, the operation control unit 135, and the display control unit 136. For example, the main control unit 131 samples the majority of the sensor electrodes 121X and the majority of the sensor electrodes 121Y.

[0036] The analog-to-digital converter (ADC) unit 132 converts an output from the electrostatic sensor 120 into a digital value. The output of the ADC unit 132 is a detection value of the capacitance at each of the intersection points of the sensor electrodes 121X and 121Y in the electrostatic sensor 120. The counter 133 counts and outputs the difference value of an output from the ADC unit 132 with respect to a reference value. The difference value is a count for a change in the output relative to the reference value. Hereinafter, the difference value is referred to as the difference value ΔAD. The reference value is the capacitance at each of the intersection points of the sensor electrodes 121X and 121Y when no finger is present around the sensor electrodes 121X and 121Y. The difference value ΔAD is the capacitance between each of the intersection points of the sensor electrodes 121X and 121Y and a finger.

[0037] The difference value ΔAD can be determined for each intersection point. The A / D converter unit 132 converts the capacitance at each of the intersection points of the sensor electrodes 121X and 121Y into a digital value. The counter 133 counts a change in an output of the A / D converter unit 132 with respect to a reference value and outputs a difference value ΔAD for each intersection point.

[0038] The calculation unit 134 determines, based on a difference value ΔAD output by the counter 133, the position of hand H in the XY coordinates and the position of hand H relative to the operating surface 105A in the Z direction. The difference value ΔAD output by the counter 133 is an example of a measured capacitance at each of the intersection points of the sensor electrodes 121X and 121Y in the electrostatic sensor 120.

[0039] The computation unit 134 determines a distance state between hand H and the operating surface 105A using a plurality of thresholds to determine an undetected state, a proximity operation, a selection operation, an acknowledgment operation, and a contact operation. The plurality of thresholds consists of eight thresholds in total, including an ON threshold and an OFF threshold to provide hysteresis properties for determining each operation: undetected state, proximity operation, selection operation, acknowledgment operation, and contact operation. As described above, the distance states between hand H and the operating surface 105A include the undetected state, the proximity state, the selection state, the acknowledgment state, and the contact state.The calculation unit 134 determines the position of hand H in each state and outputs data representing the determined position of hand H to the operation control unit 135.

[0040] The calculation unit 134 does not correct the measured capacity value when an approximation, selection, or confirmation operation is performed. This is because, for the reasons described below, the measured capacity value is generally proportional to the finger area when an approximation, selection, or confirmation operation is performed.

[0041] The computation unit 134 corrects the measured capacitance value when a contact operation is performed. This is because, for the reasons described below, the measured capacitance value is not proportional to the finger area when performing a contact operation. The computation unit 134 performs this correction, thereby increasing the detection accuracy of the hand H position during a contact operation.

[0042] The operation control unit 135 controls the operation of the coordinate input device 100 based on the position of hand H determined by the calculation unit 134. The display control unit 136 controls the display of the display device 110 based on the position of hand H determined by the calculation unit 134. The memory 137 stores programs, data, and the like that are used when the main control unit 131, the calculation unit 134, the operation control unit 135, and the display control unit 136 perform processing. <Bedienung der Operationsoberfläche 105A>

[0043] Fig. Figure 4 is a diagram of an exemplary state in which an operation is performed with the fingertip FT of hand H on the operation surface 105A of the coordinate input device 100. Fig. Figure 4 illustrates a state in which a pointing operation is performed by moving the fingertip FT of hand H vertically towards the operating surface 105A of the upper panel 105. As described above, it is preferred that such an operating procedure is carried out by vertically moving the fingertip FT towards the operating surface 105A of the upper panel 105.

[0044] The coordinate input device 100 can distinguish between the approach operation, the selection operation, the confirmation operation, and the contact operation by using the plurality of threshold values ​​described above. When the operations change from the approach operation, the selection operation, the confirmation operation, to the contact operation, the fingertip FT approaches the operating surface 105A. Accordingly, it is possible to distinguish between the approach operation, the selection operation, the confirmation operation, and the contact operation by increasing the threshold values ​​from the approach operation to the contact operation. The following describes how the accuracy of position detection can be increased during contact operations. <messwertkorrektur>

[0045] This section describes the correction of the capacitance measurements when a contact operation is performed. A capacitance measurement corresponds to a difference value ΔAD. Furthermore, the arrangement of the sensor electrodes 121X in the Y-direction and the arrangement of the sensor electrodes 121Y in the X-direction are similar. Accordingly, although this section refers to the sensor electrodes 121X, it also applies to the sensor electrodes 121Y.

[0046] When the measurement sensitivity of the coordinate input device 100 is increased, the sensor electrodes 121X are influenced not only by the part of the fingertip FT directly above the sensor electrodes 121X, but also by a part of the fingertip FT diagonally above the sensor electrodes 121X. In particular, when the distance between the sensor electrodes 121X is approximately equal to the width of the fingertip FT, the sensor electrode 121X under the central part of the fingertip FT in the Y-direction measures the capacitance generated between the part of the fingertip FT that is larger than the width of the sensor electrode 121X in the Y-direction.

[0047] In contrast, the sensor electrodes 121X below the edge of the fingertip FT in the Y-direction width do not measure the capacitance in an area outside the edge of the fingertip FT in the Y-direction width.

[0048] Accordingly, the capacitance measured by the respective sensor electrodes 121X is not proportional to the area of ​​the fingertip FT opposite the respective sensor electrodes 121X. This is because the sensor electrode 121X under the central section of the fingertip FT records a large measurement width in the Y direction, while the sensor electrodes 121X under the edge of the fingertip FT record small measurement widths in the Y direction.

[0049] Accordingly, the coordinate input device 100 corrects the measured values ​​to become smaller when the measured values ​​are large, thereby obtaining corrected measured values ​​(first corrected measured values) that are approximately proportional to the area of ​​the fingertip FT facing the respective sensor electrodes 121X. More precisely, as the measured values ​​increase, the coordinate input device 100 increases the ratio by which the correction values ​​are reduced when correcting the measured values. Through this correction of the measured values, the coordinate input device 100 can obtain corrected measured values ​​(first corrected measured values) that are approximately proportional to the area of ​​the fingertip FT facing the respective sensor electrodes 121X.By obtaining corrected measurements (first corrected measurements) that are approximately proportional to the area of ​​the fingertip FT facing the respective sensor electrodes 121X, the detection accuracy of the hand position H (fingertip position FT) in the Y-direction can be increased. Furthermore, the detection accuracy in the X-direction can also be similarly increased by using the sensor electrodes 121Y, and thus the detection accuracy of the hand position H (fingertip position FT) in both the X- and Y-directions can be increased by using sensor electrodes 121X and 121Y.

[0050] In contrast, if the fingertip FT is located at a certain distance from the surgical surface 105A, the measured values ​​at the sensor electrodes 121X directly below the edge of the fingertip FT also increase in width in the Y-direction. Accordingly, the measured values ​​of the sensor electrodes 121X directly below the edge of the fingertip FT in the Y-direction and the measured value of the sensor electrode 121X directly below the central section of the fingertip FT in the Y-direction are in a ratio that is approximately proportional to the area of ​​the fingertip FT facing the sensor electrodes 121X when the fingertip FT is at a certain distance from the surgical surface 105A.

[0051] Therefore, if the fingertip FT is located at a specific distance from the surgical surface 105A, good detection accuracy of the fingertip FT's position can be obtained without having to correct the measurements as described above. If the fingertip FT is located at a specific distance from the surgical surface 105A, this corresponds to performing an approximation operation, a selection operation, or a confirmation operation.

[0052] For the reasons described above, when performing a contact operation with increasing measured values, the coordinate input device 100 increases the ratio by which the correction values ​​are reduced when correcting the measured values. When an approximation operation, a selection operation, or a confirmation operation is performed, the coordinate input device 100 does not correct the measured values. The approximation operation, selection operation, confirmation operation, or contact operation can be determined by checking whether measured values ​​(difference values ​​ΔAD) are greater than or equal to a contact threshold value, thus indicating that a contact operation has been performed. <Messwert und erster korrigierter Messwert>

[0053] Fig. Figure 5 is a diagram illustrating an example relationship between measured values ​​and first corrected measured values. Fig. In Figure 5, the horizontal axis X represents the measured values ​​(difference values ​​ΔAD) as counted values. The vertical axis Y represents measured values ​​(difference values ​​ΔAD) without correction and the first corrected measured values, which are the corrected values ​​of the measured values ​​(difference values ​​ΔAD) as counted values. The characteristics of the measured values ​​without correction are represented by the dashed line, and the first corrected measured values ​​by the solid line.

[0054] The characteristic (dashed line) of the uncorrected measurements is that they have the same values ​​on the horizontal axis X and the vertical axis Y, represented by Y = X. In contrast, the characteristic (solid line) of the first corrected measurements shows a non-linear increase in the difference from the measurements represented by the dashed line as the values ​​of the measurements on the horizontal axis X increase.

[0055] A first corrected measurement value Y can be expressed using the following equation (1), where Cmax is the maximum value of the measurements (difference values ​​ΔAD), which is calculated on the basis of the capacitance measured at all intersection points of the majority of sensor electrodes 121X and 121Y, is the first corrected measurement value Y, and X is the measurement value. (Equation 1) Y=K1×X×(K2−X / Cmax)

[0056] It should be noted that K1 is preferably a constant less than 1 and that K2 is a value in the range of 1.7 to 2.3, and most preferably 2.

[0057] Equation (1) is a quadratic function that can be expressed in the form Y = -A (X + B)² + C, where A is a positive value, and A, B, and C are constants that satisfy equation (1).

[0058] As described above, the characteristic of the first corrected measurements (solid line) can be expressed as a quadratic function that passes through the origin, opens downwards, and lies in the coordinate plane with the x-axis and y-axis below the line Y = X. Using such a quadratic function, the first corrected measurements can be determined. The quadratic function is a continuously differentiable function.

[0059] As the measured values ​​increase, the differences between these initial corrected measurements and the measurements represented by the dashed line also increase. Accordingly, by using the initial corrected measurements, the capacitance measured at each intersection of sensor electrodes 121X and 121Y can be corrected from the relationship that the capacitance is not proportional to the area of ​​the fingertip FT facing sensor electrodes 121X and 121Y, to approximate the relationship that the capacitance is proportional to the area of ​​the fingertip FT facing sensor electrodes 121X and 121Y. By optimizing the values ​​of the constant K and the constants A, B, and C, it is possible to obtain corrected measurements (initial corrected measurements) that are approximately proportional to the area of ​​the fingertip FT facing sensor electrodes 121X and 121Y when a contact operation is performed.

[0060] It should be noted that the quadratic function can be a quadratic function that provides a downward-opening parabola, obtained by using a quadratic function such as the quadratic function described above, and has a vertex that is a first corrected measurement value corresponding to the maximum value of the measurements (difference values ​​ΔAD), which are calculated on the basis of the capacity measured at all intersection points. <Berechnung der Position der Fingerspitze FT>

[0061] The coordinate input device 100 calculates the position of the fingertip FT using three or more first corrected measurements, which comprise the maximum value of a plurality of first corrected measurements corresponding to a plurality of measurements obtained at a plurality of intersection points of the sensor electrodes 121X and 121Y, by using the maximum value and the first corrected measurements adjacent to the maximum value in the X-direction or the Y-direction. The position of the fingertip FT is the position of the fingertip FT on the operating surface 105A in the two axis directions.

[0062] More precisely, the position of the fingertip FT can be calculated, for example, using a curve approximation method or a center of gravity calculation method. Such a curve approximation method and a center of gravity calculation method are described in the Japanese, unexamined patent application Publication No. 2013-003978, which is cited as patent literature 1, and are briefly described below. <Kurvenannäherungsverfahren>

[0063] Fig. Figure 6A is a diagram showing an example of a curve approximation method. Fig. Figure 6A shows exemplary initial corrected measurements, which are corrected values ​​of measured values ​​(difference values ​​ΔAD) obtained at eight intersection points arranged in the X-direction. These eight intersection points are designated X0 to X7 for differentiation and are referred to here as intersection points X0 to X7. The X-coordinate of intersection point X0 is zero. Fig. 6A is the first corrected measurement of the intersection point X5, for example the maximum value (peak value).

[0064] The calculation unit 134 calculates first corrected measured values ​​for the intersection point X5, at which the maximum measured value is obtained, and for the intersection points X4 and X6 adjacent to the intersection point X5, and performs the curve approximation procedure using the change in the first corrected measured values.

[0065] For example, the computation unit 134 calculates an X-coordinate Xft, which is an X-coordinate of the position of the fingertip FT, based on the first three corrected measurements obtained from the three measurements of intersection point X5 and two intersection points X4 and X6 adjacent to intersection point X5 in the X-direction, using the quadratic curve approximation method with the following equation (2), where the first corrected measurement of the intersection point (Xpk, Ypk) at which the maximum measurement is obtained is called Cpk, the first corrected measurement of the intersection point (Xpk-1, Ypk) adjacent to the intersection point (Xpk, Ypk) in the -X-direction is called Cpk-1, and the first corrected measurement of the intersection point (Xpk+1, Ypk) adjacent to the intersection point (Xpk, Ypk) in the +X-direction is called Cpk+1 designated.Furthermore, the resolution, which is the interval between the sensor electrodes 121X and 121Y with respect to the unit coordinates, is called RES, and the X-coordinate of the intersection point at which the maximum value Cmax of the measured values ​​(difference values ​​ΔAD) is reached is called Xmax. (Equation 2) Xft=Cpk−1−Cpk+1(Cpk−1+Cpk+1−2×Cpk)×2×RES+Xmax

[0066] It should be noted that instead of the first corrected measurement Cpk-1, the first corrected measurement of the intersection point (Xpk-2, Ypk) adjacent to the intersection point (Xpk-1, Ypk) in the -X direction can also be used. Furthermore, instead of the first corrected measurement Cpk+1, the first corrected measurement of the intersection point (Xpk+2, Ypk) adjacent to the intersection point (Xpk+1, Ypk) in the +X direction can be used. These first corrected measurements are the first corrected measurements corresponding to the three or more measurements that comprise the maximum value of the majority of measurements.

[0067] Furthermore, by performing a similar processing operation, a Y-coordinate Yft, which is a Y-coordinate of the fingertip position FT, can be calculated for the majority of the intersection points arranged in the Y-direction. The position of the fingertip FT is expressed using XY coordinates (Xft, Yft). <Verfahren der Zentroidberechnung>

[0068] Fig. 6B is a diagram showing an example of a center of gravity calculation method. Fig. 6B shows, similarly to Fig. 6A, first corrected measured values, which are corrected values ​​of measured values ​​(difference values ​​ΔAD) determined, for example, at eight intersection points arranged in the X-direction. These eight intersection points are designated X0 to X7 for differentiation and are referred to here as intersection points X0 to X7. The X-coordinate of intersection point X0 is zero. In Fig. 6B is, as an example, the first corrected measurement of the intersection point X5, the maximum value (peak value).

[0069] The calculation unit 134 calculates the change between the first corrected measured values ​​of the intersection points X0 to X7, which are adjacent in the X-direction. Then, the calculation unit 134 performs a center of gravity calculation procedure for intersection points (intersection points X3 to X7 in...). Fig. 6B) in an area which includes at least intersection points where the changes are greater than or equal to a first threshold value which follows successively in the X direction from the intersection point X5, where the maximum value of the first corrected measurements is obtained.

[0070] The calculation unit 134 calculates a center of gravity position XG by weighting the first corrected measurements from the intersection points X3 to X7 that are greater than or equal to the first threshold value. The center of gravity position XG is the X-coordinate of the fingertip position FT.

[0071] Furthermore, the Y-coordinate YG, which is the Y-coordinate of the fingertip's position FT, can be calculated by performing a similar process on a plurality of intersection points arranged in the Y-direction to calculate the center of gravity. The position of the fingertip FT is expressed using the XY coordinates (XG, YG).

[0072] In the above description, the procedure for calculating the XY coordinates of the fingertip FT, when a contact operation has been performed, using the curve approximation method or the center of gravity calculation method using the first corrected measured values, which are the corrected values ​​of the measured values ​​(difference values ​​ΔAD) obtained at the intersection points of the sensor electrodes 121X and 121Y.

[0073] However, such a method for calculating the XY coordinates of the fingertip FT can be used not only for the contact operation, but also, for example, for a confirmation operation, a selection operation, or an approximation operation. Compared to contact operations, the measured values ​​(difference values ​​ΔAD) obtained at the intersection points of the sensor electrodes 121X and 121Y are small when confirmation operations, selection operations, and approximation operations are performed. Accordingly, it is preferable to calculate the XY coordinates of the fingertip FT using the curve approximation method or the center-of-gravity calculation method by using second corrected measured values, which are values ​​obtained by further correction of the first corrected measured values ​​as described below.

[0074] Let C(m) be the measured value obtained at an m-th intersection point Xm from a plurality of intersection points arranged in the X-direction, C1(m) be the first corrected measured value obtained by correcting the measured value C(m), and W be the weight. A second corrected measured value C2(m), obtained by weighted averaging using the measured value C(m), the first corrected measured values ​​C1(m), and the weight W, can be expressed by the following equation (3). [Equation 3] C2(m)=[{100−W×C(m)}+W×C1(m)] / 100

[0075] Here, the weight W can be expressed by the following equation (4), where Th is the contact threshold for the measured values ​​to determine that a contact operation has been carried out, and Cmax is the maximum value of the measured values ​​obtained at all intersection points from the majority of sensor electrodes 121X and 121Y. (Equation 4) W=LIMIT((100×Cmax) / / Th,0,100)

[0076] Equation (4) can be expressed using a limit function (LIMIT) that limits the weight W to a numerical value of 0 or greater and 100 or less. If a value ((100 × Cmax) / W), obtained by dividing the maximum measured value Cmax by the contact threshold Th and multiplying it by 100, exceeds 100, the weight is limited to 100.

[0077] As described above, the XY coordinates of the fingertip FT can be calculated by replacing the first corrected measurement C1(m) with the second corrected measurement C2(m). That is, the first corrected measurement C1(m) in the curve approximation method or the center of gravity calculation method described above can be replaced by the second corrected measurement C2(m) to calculate the XY coordinates of the fingertip FT.

[0078] For example, if the maximum value of the measurements at all intersection points is greater than or equal to the contact threshold Th, the XY coordinates of the fingertip FT can be calculated using the curve approximation method or the center of gravity calculation method, using the first corrected measurement. If the maximum value of the measurements at all intersection points is less than the contact threshold Th, the XY coordinates of the fingertip FT can be calculated using the second corrected measurement, either the curve approximation method or the center of gravity calculation method.

[0079] It should be noted that equation (1) for calculating a first corrected measurement can be expressed by the following equation (5), using the measurement C(m) and the first corrected measurement C1(m), where K1 is a constant less than 1 and K2 is a predetermined constant. (Equation 5) C1(m)=K1×C(m)×(K2−C(m) / Cmax)

[0080] Furthermore, by removing Xmax from equation (2) an equation for calculating an interpolation amount D for the interpolation of an X-coordinate or a Y-coordinate can be obtained, as shown in equation (6). [Equation 6] D=Cpk−1−Cpk+1(Cpk−1+Cpk+1−2×Cpk)×2×RES <flussdiagramm>

[0081] Fig. 7A is a flowchart showing an example of the processing to be carried out by the computation unit 134 to calculate the position of the fingertip FT. Fig. 7B is a flowchart which shows an example of interpolation processing for coordinates in steps S4 and S8 in Fig. 7A is shown.

[0082] When the computation unit 134 begins processing, the computation unit 134 records measured values ​​at the respective intersection points of the sensor electrodes 121X and 121Y (step S1).

[0083] The calculation unit 134 determines an intersection point (Xpk, Ypk) at which the maximum measured value of all intersection points is obtained (step S2).

[0084] The calculation unit 134 substitutes the measured value at the intersection (Xpk-1, Ypk) into Cin[0], substitutes the measured value at the intersection (Xpk, Ypk) into Cin[1], and substitutes the measured value at the intersection (Xpk+1, Ypk) into Cin[2] (step S3). Cin[i] is a region in the memory of the control device 130 into which measured values ​​are substituted, and i is an integer that can take a value from 0 to 3.

[0085] The intersection point (Xpk-1, Ypk) is an intersection point adjacent to the intersection point (Xpk, Ypk) where the maximum measurement is obtained in the -X direction, and the intersection point (Xpk+1, Ypk) is an intersection point adjacent to the intersection point (Xpk, Ypk) where the maximum measurement is obtained in the +X direction.

[0086] The calculation unit 134 performs an interpolation process for the X-coordinate (step S4). The process in step S4 is a subroutine process. Here, the interpolation process in step S4 is described with reference to... Fig. 7B described. <koordinaten-interpolationsverarbeitung>

[0087] Here, the interpolation processing for the X-coordinate is implemented as a subroutine of the process in step S4 with reference to Fig. 7B described.

[0088] The calculation unit 134 sets i to zero (step S11). That is, i = 0.

[0089] The calculation unit 134 calculates a weight W using equation (4) (step S12).

[0090] The computation unit 134 calculates a first corrected measurement value for Cin[i] using equation (5) (step S13).

[0091] The computation unit 134 calculates a second corrected measurement value for Cin[i] using equation (3) (step S14).

[0092] The calculation unit 134 increments i (step S15). That is, i = i + 1.

[0093] The calculation unit 134 determines whether i is three or more (step S16).

[0094] If the computation unit 134 determines that i is not three or greater (S16: NO), the processing returns to step S13. Consequently, the processing is repeated in steps S13 to S15 until i = 3, and first corrected measurements and second corrected measurements are calculated for Cin[0] to Cin[2].

[0095] In step S16, if the computation unit 134 determines that i is three or greater (S16: YES), the computation unit 134 calculates an interpolation amount D for the X-coordinate using equation (6) (step S17). In equation (6), the interpolation amount D can be calculated using the second corrected measurement obtained for Cin[1] as Cpk, the second corrected measurement obtained for Cin[0] as Cpk-1, and the second corrected measurement obtained for Cin[2] as Cpk+1.

[0096] It should be noted that the processing in step S14 can be omitted. In such a case, if the interpolation amount D for the X-coordinate is calculated using equation (6) in step S17, the interpolation amount D can be calculated using the first corrected measurement obtained for Cin[1] as Cpk, the first corrected measurement obtained for Cin[0] as Cpk-1, and the first corrected measurement obtained for Cin[2] as Cpk+1.

[0097] The calculation unit 134 calculates the X-coordinate of the fingertip FT (step S5). The calculation unit 134 calculates the X-coordinate of the fingertip FT by adding the interpolation amount D, for the X-coordinate obtained in step S17, to the X-coordinate Xmax of the intersection point at which the maximum value Cmax of the measured values ​​(difference values ​​ΔAD) is obtained.

[0098] The calculation unit 134 then performs a calculation for the Y-coordinate.

[0099] The calculation unit 134 substitutes the measured value at the intersection point (Xpk, Ypk-1) in Cin[0], substitutes the measured value at the intersection point (Xpk, Ypk) in Cin[1] and substitutes the measured value at the intersection point (Xpk, Ypk+1) in Cin[2] (step S6).

[0100] The intersection point (Xpk, Ypk-1) is an intersection point adjacent to the intersection point (Xpk, Ypk) where the maximum measurement is obtained in the -Y direction, and the intersection point (Xpk, Ypk+1) is an intersection point adjacent to the intersection point (Xpk, Ypk) where the maximum measurement is obtained in the +Y direction.

[0101] The processing unit 134 performs interpolation processing for the Y-coordinate (step S7). The operation in step S7 is a subroutine operation. Similar to the subroutine processing in step S4, the processing unit 134 performs the interpolation processing for the Y-coordinate according to the sequence in Fig. 7B to calculate an interpolation amount D for the Y-coordinate.

[0102] The computation unit 134 calculates the Y-coordinate of the fingertip FT (step S8). The computation unit 134 calculates the X-coordinate of the fingertip FT by adding the interpolation amount D obtained in step S17 for the Y-coordinate to the Y-coordinate Ymax of the intersection point where the maximum value Cmax of the measured values ​​(difference values ​​ΔAD) is obtained. <simulationsergebnisse>

[0103] Fig. This is a diagram with examples of simulation results. Fig. The horizontal axis X represents the X-coordinates and the vertical axis the capacity (count values). The intersection points of the sensor electrodes 121X and 121Y are located at Fig. at three points with X-coordinates 500, 1500 and 2500. The intersection points at X-coordinate 1500 are the points where the maximum measured values ​​were achieved.

[0104] The in Fig. The characteristics represented by the solid lines are those obtained by connecting the second corrected measurements obtained at the three intersection points. The quadratic curves that correspond to the characteristics of the lines represented by the solid lines are quadratic curves fitted to the second corrected measurements obtained at the three intersection points using the curve approximation method. The white diamond (◇) indicates the maximum value of the quadratic curve fitted to the second corrected measurements at the three intersection points using the curve approximation method. In other words, the x-coordinate of the white diamond (◇) represents the x-coordinate shifted by correction from the intersection point (intersection of the x-coordinate 1500) at which the maximum measurement was obtained.

[0105] The characteristics represented by the dashed lines are those obtained by connecting the measurements taken at the three intersection points. The quadratic curves that correspond to the characteristics of the lines represented by dashed lines are quadratic curves fitted to the measurements taken at the three intersection points using the curve approximation method. The black diamond (♦) indicates the maximum value of the quadratic curve fitted to the measurements taken at the three intersection points using the curve approximation method. In other words, the x-coordinate of the black diamond (♦) represents the x-coordinate determined without correction.

[0106] As in Fig. As shown, the calculated X-coordinate of the maximum value was closer to the measured X-coordinate than the correct X-coordinate when the measured values ​​were used directly to calculate the coordinate. When calculating the X-coordinate by correcting the measured value according to the method according to the invention, the coordinate calculated was closer to the correct X-coordinate. It should be noted that although the X-coordinates in Fig. are shown, but it has been confirmed that this also applies to the Y-coordinates.

[0107] As the measured values ​​increased when they were corrected and the first corrected values ​​were calculated, the ratio at which the first corrected values ​​were reduced was increased. This method effectively brought the calculated coordinate closer to the coordinate directly below the center of the finger. It has been shown that by correcting the measured values ​​using the method according to the invention, error reduction is possible even when using large electrodes to achieve high detection sensitivity. It is assumed that by correcting measured values ​​using the method according to the invention, the corrected values ​​come closer to values ​​proportional to the area of ​​the fingertip FT facing the sensor electrodes 121X and 121Y, thereby reducing errors.

[0108] In the above description, as in Fig. As represented by the solid line in Figure 5, the characteristics of the first corrected measurements can be expressed as a quadratic function passing through the origin, opening downwards, and lying below the line Y = X in the coordinate plane with the X-axis and the Y-axis. However, the characteristics of the first corrected measurements are not limited to those expressed by such a quadratic function and can be further described in Figure 5. Fig. 9A to Fig. The characteristics shown in 9C are as follows. Fig. 9A to Fig. 9C are examples of variations in the properties of the first corrected measurements. <Fig. 9A>

[0109] The solid line in Fig. The characteristic of the first corrected measurements shown in Figure 9A is expressed as a function that passes through the origin, lies below the line Y = X, and decreases exponentially in the coordinate plane with respect to both the x-axis and the y-axis. The exponentially decreasing function is a continuously differentiable function. The function represented by equation (7) below can be used as an example of such a function. The first corrected measurements with such characteristics can be used. (Equation 7) Y=k1(1−e−Xk2)

[0110] If the characteristics of the first corrected measurements, which are represented by the solid line in Fig. As shown in 9A, the difference between the measured values ​​increases non-linearly as the values ​​of the measured values ​​on the horizontal axis X increase. <Abb. 9B>

[0111] The solid line in Fig. The characteristics of the first corrected measurements shown in Figure 9B are, in the coordinate plane with the X-axis and the Y-axis, characteristics that pass through the origin. In the range where X is 0 to 300, they are equal to the line Y = X, but in the range where X is 300 or greater, they bend below the line Y = X and have a gentler slope than the line Y = X. The first corrected measurements with such characteristics can be used.

[0112] The characteristics of the first corrected measurements, represented by the solid line in Fig. The characteristics shown in Figure 9B can be expressed as Y = αX - β in the range where X is 300 to 1000, where α is a positive constant less than 1 and β is a positive constant. Such an equation can be obtained by subtracting a first constant from a measurement represented by Y = X, multiplying the result by a second constant, and adding a third constant to the result. As an example, the characteristics of the first corrected measurements in Figure 9B are shown in Figure 9B. Fig. This can be expressed as Y = 300 + (X - 300) × 0.4. The first constant is 300 in X - 300, the second constant is 0.4, and the third constant is 300 in 300 + 300.

[0113] If the in Fig. When using the characteristics of the first corrected measurements shown in Figure 9B, the difference from the measurements represented by the dashed line increases linearly as the measurements on the horizontal axis X reach a predetermined value (300) or higher. It should be noted that the characteristics may be such that the difference from the measurements represented by the dashed line increases non-linearly as the measurements on the horizontal axis X reach the predetermined value (300) or higher. <Abb. 9C>

[0114] The in Fig. The characteristics of the first corrected measurements shown in Figure 9C are, in the coordinate plane with the X-axis and the Y-axis, characteristics that pass through the origin, are equal to the line Y = X in the range where X is 0 to 500, but bend below the line Y = X in the range where X is 500 or greater and become constant at Y = 500. The first corrected measurements with such characteristics can be used.

[0115] If the in Fig. Using the characteristics of the first corrected measurements shown in Figure 9C, the difference from the measurements expressed by the dashed line increases linearly when the measurements on the horizontal axis X reach a predetermined value (500) or more. <vorteile>

[0116] The coordinate input device 100 comprises the insulating substrate 125, the sensor electrodes 121X and 121Y, which have the plurality of intersection points (detection points) and are arranged on the insulating substrate 125, the upper panel 105, which has the operating surface that can be operated with the fingertip FT (operating body) and covers the sensor electrodes 121X and 121Y, the AD converter unit 132 and the counter 133 (measuring circuit), which measure the capacitance at each of the plurality of intersection points, and the calculation unit 134 (calculation circuit), which calculates a position of the operating body in two axis directions on the operating surface based on the measured capacitance values ​​at the plurality of detection points.The calculation unit 134 corrects the measurement for each of three or more measurements that comprise the maximum value of the majority of measurements obtained at the majority of detection points, and calculates a first corrected measurement to reduce the differences between the three or more measurements that comprise the maximum value. It then calculates the position of the surgical body in the biaxial directions on the surgical surface using the first corrected measurement corresponding to the maximum value and the first corrected measurements corresponding to the measurements adjacent to the maximum value in one of the biaxial directions. As the measurements become larger when they are corrected and the first corrected measurements are calculated, the ratio at which the first corrected measurements are reduced is increased.In other words, the value obtained by dividing the first corrected measurement of the measurement adjacent to the position where the maximum value is measured by the first corrected measurement of the maximum value is greater than the value obtained by dividing the measurement adjacent to the position where the maximum value is measured by the maximum value itself. With this configuration, when large sensor electrodes are used to increase detection sensitivity, the occurrence of errors can be reduced by preventing the central position of the operating body from being calculated as a position closer to the central position of the electrode than its actual position.

[0117] According to the coordinate input device 100 with increased detection sensitivity, the occurrence of errors can be reduced.

[0118] The calculation unit 134 can calculate the first corrected measurements in such a way that the differences between the measurements and the first corrected measurements increase non-linearly as the measurements (difference values ​​ΔAD) increase, or calculate the first corrected measurements in such a way that the differences between the measurements and the first corrected measurements increase non-linearly or linearly as the measurements become greater than or equal to a predetermined value.

[0119] Furthermore, the computation unit 134 corrects the measured values ​​using a function that represents the first corrected measured values ​​of the measured values, passes through the origin where both the measured value and the first corrected measured value are zero, and is continuously differentiable. With this configuration, the ratio between the measured values ​​and the first corrected measured values ​​changes uniformly, and if the fingertip FT is moved at a constant speed along the operating surface 105A, it is possible to suppress discontinuous changes in the calculated speed.

[0120] The calculation unit 134 calculates the first corrected measured values ​​using a function that represents the first corrected measured values ​​and is a quadratic function in a coordinate plane with an x-axis and a y-axis, where the measured value is x and the first corrected measured value is y, passes through the origin, and extends downwards. According to the coordinate input device 100, which is capable of calculating first corrected measured values ​​with relatively little computational effort and achieving both improved detection sensitivity and increased detection accuracy, this device can be provided.

[0121] The quadratic function is a quadratic function with a vertex corresponding to the first corrected measurement, which in turn corresponds to the maximum value of the measured values. Experiments have confirmed that increasing the correction ratio of the measured value at the intersection point directly below the center of the fingertip (FT) improves the detection accuracy of the fingertip position (FT). Accordingly, the detection accuracy of the fingertip position (FT) can be increased with relatively little computational effort.

[0122] The computation unit 134 calculates the first corrected measurement Y using the following equation (8), where measurement X is the first corrected measurement Y and maximum value Cmax is the maximum value. (Equation 8) Y=K1×X×(K2−X / Cmax)

[0123] In the equation, K is a constant less than 1, and K2 is a value in the range of 1.7 to 2.3. The coefficient K2 can be easily determined by deciding by how much the maximum value of the measurements obtained at the intersection point directly below the center of the fingertip FT should be reduced, which simplifies the construction.

[0124] The calculation unit 134 calculates the first corrected measurements using a function in which the first corrected measurements decrease exponentially. Accordingly, the ratio between the measured values ​​and the first corrected measurements changes uniformly, and if the fingertip FT is moved along the operating surface 105A at a constant speed, it is possible to suppress discontinuous changes in the calculated speed.

[0125] The calculation unit 134 does not correct the measured values ​​if they are less than the predetermined value, and calculates the first corrected measured values ​​when they become greater than or equal to the predetermined value. The first corrected measured values ​​can be calculated based on the measured values ​​using a simple relational expression.

[0126] The calculation unit 134 calculates the first corrected measurements when the measured values ​​are greater than or equal to the predetermined value by subtracting a first constant from the measured value, multiplying the result by a second constant, and adding a third constant to the result. Using this relatively simple relational expression, first corrected measurements can be calculated based on the measured values.

[0127] If the measured values ​​are greater than or equal to the predetermined value, the calculation unit 134 calculates the first corrected measured values ​​by correcting the measured values ​​to a constant value. The first corrected measured values ​​can be calculated based on the measured values ​​using a simple relational expression.

[0128] The calculation unit 134 is configured to calculate distances from the sensor electrodes 121X and 121Y to the operating body and to calculate the position of the operating body in the biaxial directions on the operating surface using the first corrected measurement corresponding to the maximum value and the first corrected measurements corresponding to the measurements adjacent to the maximum value in one of the biaxial directions, and if the maximum value of the majority of measurements is less than the contact threshold, a second corrected measurement is calculated for each of the three or more measurements that include the maximum value by weighting the measurement and the first corrected measurement corresponding to the measurement according to a ratio of the maximum value of the majority of measurements to the contact threshold.and the position of the surgical body in the biaxial directions on the surgical surface is calculated using the second corrected measurement, which corresponds to the maximum value, and the second corrected measurements, which correspond to the measurements adjacent to the maximum value in one of the biaxial directions. For example, if the measurements (difference values ​​ΔAD) obtained at the intersection points of sensor electrodes 121X and 121Y are small compared to those obtained during a contact operation, the XY coordinates of the fingertip FT can be easily calculated using the second corrected measurements.

[0129] The computation unit 134 fits a quadratic curve to the first corrected measurement, which corresponds to the maximum value, and to the first corrected measurements, which correspond to the measurements adjacent to the maximum value in one of the biaxial directions, and calculates the position of a vertex of the quadratic curve as the position of the surgical body in the biaxial directions on the surgical surface. Because the position of a vertex of the quadratic curve is fitted to the first corrected measurements, the position of the fingertip FT can be calculated with high accuracy. This is particularly useful when the distance between the sensor electrodes 121X and 121Y is large (or equivalent) relative to the width of the fingertip FT.

[0130] The calculation unit 134 calculates the position of a center of gravity by weighting the first corrected measurements greater than or equal to a threshold value, the first corrected measurement corresponding to the maximum value, and the first corrected measurements corresponding to those adjacent to the maximum value. This weighting determines the position of the surgical body in the two-axis directions on the surgical surface. The position of the fingertip FT can be calculated with high accuracy as the position of a center of gravity adapted to the first corrected measurements. This is particularly useful when the distance between the sensor electrodes 121X and 121Y is small relative to the width of the fingertip FT.

[0131] If the maximum value of the majority of measurements is greater than or equal to the contact threshold, the calculation unit 134 fits a quadratic curve to the first corrected measurement corresponding to the maximum value and to the first corrected measurements corresponding to the measurements adjacent to the maximum value in one of the biaxial directions, and calculates the position of a vertex of the quadratic curve as the position of the operating body in the biaxial directions on the operating surface; and if the maximum value of the majority of measurements is less than the contact threshold, a quadratic curve is fitted to the second corrected measurement corresponding to the maximum value and to the second corrected measurements corresponding to the measurements adjacent to the maximum value in one of the biaxial directions.The system adjusts the position of a vertex of the quadratic curve and calculates the position of the surgical body in the biaxial directions on the surgical surface. Depending on the relationship between the maximum value of a plurality of measurements and a contact threshold, a curve approximation method with high detection accuracy of the fingertip FT position can be selected.

[0132] The calculation unit 134 calculates, if the maximum value of the majority of measured values ​​is greater than or equal to the contact threshold, a position of a center of gravity, which is obtained by weighting the first corrected measured values ​​that are greater than or equal to the threshold, from the first corrected measured value corresponding to the maximum value, and the first corrected measured values ​​that correspond to the measured values ​​next to the maximum value, as the position of the operating body in the two axis directions on the operating surface; and if the maximum value of the majority of measured values ​​is less than the contact threshold, a position of a center of gravity is obtained by weighting the second corrected measured values ​​that are greater than or equal to the threshold, from the second corrected measured value corresponding to the maximum value, and the second corrected measured values ​​that correspond to the measured values ​​next to the maximum value.The position of the surgical body in the two-axis directions on the surgical surface is calculated. Depending on the relationship between the maximum value of a plurality of measurements and a contact threshold, a center of gravity calculation method with high detection accuracy of the fingertip FT position can be selected.

[0133] Although the coordinate input device has been described according to the exemplary embodiments of the disclosure above, it is to be understood that the disclosure is not limited to these specifically disclosed embodiments, and various modifications or changes may be made without deviating from the scope of the claims.

[0134] This international application claims the benefits of Japanese patent application No. 2023-005965, which was filed on January 18, 2023, and the entire contents of which are hereby incorporated by reference. Reference symbol list 100 electrostatic coordinate input device 101 cases 105 Top Panel 105A Operating surface 110 Display device 120 Electrostatic Sensor 130 Control device 121X, 121Y Sensor electrode 131 Main control unit 132 AD converter unit 133 counters 134 units of calculation 135 Operation Control Unit 136 Display control unit 137 storage QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2013-003978

[0003] JP 2023-005965

[0134] < / vorteile> < / simulationsergebnisse> < / flussdiagramm> < / messwertkorrektur>

Claims

[1] A coordinate input device which includes: an insulating substrate; Sensor electrodes having a plurality of detection points, wherein the sensor electrodes are arranged on the insulating substrate; an upper panel which has an operating surface that can be operated by using an operating body, wherein the upper panel covers the sensor electrodes; a measuring circuit configured to measure capacitance at each of the plurality of detection points; and a computation circuit configured to calculate the position of the operating body in two-axis directions on the operating surface based on the capacitance measurements at the plurality of detection points, wherein the calculation circuit, For each of three or more measurements that comprise the maximum value of the majority of measurements obtained at the majority of detection points, the measurement is corrected and a first corrected measurement is calculated to reduce differences between the three or more measurements that comprise the maximum value, and The position of the surgical body in the biaxial directions on the surgical surface is calculated using the first corrected measurement which corresponds to the maximum value and the first corrected measurements which correspond to the measurements next to the maximum value in one of the biaxial directions. [2] The coordinate input device according to claim 1, wherein the first corrected measurements are smaller than the measurements, and the calculation circuit the first corrected measurements are calculated such that the differences between the measurements and the first corrected measurements increase non-linearly as the measurements increase, or the first corrected measurements are calculated such that the differences between the measurements and the first corrected measurements increase non-linearly or linearly as the measurements become greater than or equal to a predetermined value. [3] The coordinate input device according to claim 2, wherein the computation circuit corrects the measured values ​​using a function that represents the first corrected measured values ​​of the measured values, passes through the origin at which both the measured value and the first corrected measured value are zero, and is continuously differentiable. [4] The coordinate input device according to claim 2, wherein the calculation circuit calculates the first corrected measured values ​​using a function that represents the first corrected measured values ​​of the measured values ​​and that is a quadratic function, in a coordinate plane with an X-axis and a Y-axis, when the measured value is X and the first corrected measured value is Y, passes through the origin and opens downwards. [5] The coordinate input device according to claim 4, wherein the quadratic function is a quadratic function with a vertex which corresponds to the first corrected measurement which corresponds to the maximum value. [6] The coordinate input device according to claim 2, wherein The calculation circuit calculates the first corrected measurement Y using the following equation (1), where the measurement X is, the first corrected measurement Y is, and the maximum value Cmax is, [Equation 1] Y=K1×X×(K2−X / Cmax) where K is a constant less than 1 and K2 is a value in the range of 1.7 to 2.

3. [7] The coordinate input device according to claim 2, wherein the calculation circuit calculates the first corrected measured values ​​using a function in which the first corrected measured values ​​decrease exponentially. [8] The coordinate input device according to claim 2, wherein the calculation circuit does not correct the measured values ​​when the measured values ​​are less than the predetermined value, and calculates the first corrected measured values ​​when the measured values ​​become greater than or equal to the predetermined value. [9] The coordinate input device according to claim 8, wherein the calculation circuit calculates the first corrected measured values ​​when the measured values ​​are greater than or equal to the predetermined value by subtracting a first constant from the measured value, multiplying the result by a second constant and adding a third constant to the result. [10] The coordinate input device according to claim 8, wherein the calculation circuit, when the measured values ​​are greater than or equal to the predetermined value, calculates the first corrected measured values ​​by correcting the measured values ​​to a constant value. [11] The coordinate input device according to any one of claims 3 to 10, wherein the calculation circuit is configured to calculate distances from the sensor electrodes to the operating body, and if the maximum value of the majority of measurements is greater than or equal to a contact threshold value, to determine whether the operating body and the operating surface are in contact with each other, the position of the surgical body in the biaxial directions on the surgical surface is calculated using the first corrected measurement which corresponds to the maximum value, and the first corrected measurements which correspond to the measurements adjacent to the maximum value in the biaxial directions, and If the maximum value of the majority of measurements is less than the contact threshold, for each of the three or more measurements that include the maximum value, a second corrected measurement is calculated by weighting the measurement and the first corrected measurement corresponding to the measurement according to a ratio of the maximum value of the majority of measurements to the contact threshold, and the position of the operating body in the biaxial directions on the operating surface is calculated using the second corrected measurement corresponding to the maximum value and the second corrected measurements corresponding to the measurements adjacent to the maximum value in one of the biaxial directions. [12] The coordinate input device according to one of claims 1 to 9, wherein the calculation circuit adapts a quadratic curve to the first corrected measured value corresponding to the maximum value and the first corrected measured values ​​corresponding to the measured values ​​adjacent to the maximum value in one of the biaxial directions, and calculates the position of a vertex of the quadratic curve as the position of the operating body in the biaxial directions on the operating surface. [13] The coordinate input device according to one of claims 1 to 10, wherein the calculation circuit calculates a position of a center of gravity, which is obtained by weighting the first corrected measured values ​​greater than or equal to a threshold value from the first corrected measured value corresponding to the maximum value and the first corrected measured values ​​corresponding to the measured values ​​adjacent to the maximum value, as the position of the operating body in the two-axis directions on the operating surface. [14] The coordinate input device according to claim 11, wherein the calculation circuit if the maximum value of the majority of measurements is greater than or equal to the contact threshold, a quadratic curve is fitted to the first corrected measurement corresponding to the maximum value and the first corrected measurements corresponding to the measurements adjacent to the maximum value in one of the biaxial directions, and the position of a vertex of the quadratic curve is calculated as the position of the operating body in the biaxial directions on the operating surface, and If the maximum value of the majority of measurements is less than the contact threshold, a quadratic curve is fitted to the second corrected measurement, which corresponds to the maximum value, and the second corrected measurements, which correspond to the measurements adjacent to the maximum value in one of the biaxial directions, and the position of a vertex of the quadratic curve is calculated as the position of the operating body in the biaxial directions on the operating surface. [15] The coordinate input device according to claim 11, wherein the calculation circuit If the maximum value of the majority of measurements is greater than or equal to the contact threshold, a position of a center of gravity, which is obtained by weighting the first corrected measurements that are greater than or equal to the threshold, from the first corrected measurement corresponding to the maximum value, and the first corrected measurements corresponding to the measurements adjacent to the maximum value, is calculated as the position of the operating body in the biaxial directions on the operating surface, and If the maximum value of the majority of measurements is less than the contact threshold, a position of a center of gravity is calculated, which is obtained as the position of the operating body in the biaxial directions on the operating surface by weighting the second corrected measurements that are greater than or equal to the threshold, from the second corrected measurement that corresponds to the maximum value, and the second corrected measurements that correspond to the measurements adjacent to the maximum value.

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