JP2013025427A - Input device equipped with load sensors and input coordinate conversion method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an input device equipped with load sensors which prevents deviation of a detection position of an input position coordinate while allowing easy transformation from the input position coordinate to a coordinate of display coordinate system when a rotation angle of a surface panel is changed, and an input coordinate conversion method.SOLUTION: The input device comprises: a surface panel having a display region for viewing image and character data; multiple load sensors arranged so as to detect an input position onto the surface panel; a display coordinate system for defining a display direction of the image and character data according to a rotation angle of the surface panel; a sensor coordinate system for defining an input position onto the surface panel; input position calculation means for calculating an input position coordinate in the sensor coordinate system from load data of the multiple load sensors; and coordinate transformation means for transforming the input position coordinate to the display coordinate system on the basis of the rotation angle of the surface panel.

Description

  The present invention relates to an input device using a load sensor and an input coordinate conversion method thereof, and in particular, prevents a detection position shift of the input position coordinates and displays the input position coordinates even when the rotation angle of the surface panel changes. The present invention relates to an input device using a load sensor and an input coordinate conversion method thereof that can be easily converted into the coordinates of the input.

  Currently, as a display unit of a portable electronic device or the like, a translucent input device for performing coordinate input by operating with a finger or the like while visually recognizing a menu item or an object of a display image is used. As such an input device, Patent Document 1 discloses an input device using a load sensor. The input device disclosed in Patent Literature 1 can detect the pressed position of the XY coordinates and the load in the Z direction from each output value from the plurality of load sensors by a predetermined calculation formula. Therefore, in an input device using a plurality of load sensors, it is possible to select a menu item or image data displayed on the display image and simultaneously select a processing content to be executed according to the magnitude of the input load. Various operations can be performed.

  Patent Document 2 and Patent Document 3 disclose a method of displaying an image of a display unit in an appropriate direction when a mobile information terminal such as a mobile phone is rotated or when a display unit of a mobile information terminal is rotated. It is disclosed. As disclosed in Patent Document 3, the coordinate origin of the display coordinate system is set to the upper left corner of the display unit as viewed from the user, and when the display unit is rotated, the coordinate origin in the display unit is set. Is changed so that it is always positioned at the upper left corner of the display as viewed from the user. Thereby, an image can be displayed in an appropriate direction when viewed from the user regardless of the rotation angle of the display unit or the portable information terminal.

  In recent years, even when the rotation angle of a portable information terminal changes, it is possible to display an image or the like appropriately and to realize various input operations, and a display unit of an electronic device such as a portable information terminal. As an example, the mounting of an input device using a load sensor has been studied.

  In such a case, there are two coordinate systems: a display coordinate system that defines the display direction of the display image, and a sensor coordinate system that defines the input position coordinates. Even when the display coordinate system is rotated, the input position is appropriately set. It is necessary to make the display coordinate system coincide with the sensor coordinate system so that they can be detected easily. FIG. 10 schematically shows a plan view of a conventional input device 101. FIG. 10A shows the input device 101 in the initial state, and FIG. 10B shows the input device when rotated 90 degrees. 101 is shown. As shown in FIG. 10A, the display coordinate origin 130a of the display coordinate system 130 and the sensor coordinate origin 131a of the sensor coordinate system 131 in the initial state are both set at the upper left corner of the display area 111. Therefore, the display position coordinates of the image or menu item displayed on the display coordinate system 130 and the input position coordinates detected by the sensor coordinate system 131 can be matched.

  As shown in FIG. 10B, when the input device 101 is rotated by 90 °, the display coordinate origin 130a is coordinate-transformed so as to be positioned at the upper left corner as viewed from the user side, and the display direction is rotated. Similarly, the sensor coordinate origin 131a is converted into the upper left corner as viewed from the user side. Accordingly, when the input device 101 is rotated, the sensor coordinate system 131 is rotated together with the rotation of the display coordinate system 130 so that the display position coordinates of the display coordinate system 130 and the input position coordinates of the sensor coordinate system 131 coincide. It will be.

JP 2006-126997 A JP 2005-229490 A JP 2008-118286 A

  In the input device 101 using a load sensor, a plurality of load sensors 120a to 120d are used as shown in FIG. 10, and a load position is calculated from each load data according to a predetermined calculation. Since the load sensors 120a to 120d have different output characteristics and sensitivities due to variations in the manufacturing process, etc., even when the same load is applied to the load sensors 120a to 120d, the output values vary to some extent. It will occur. Further, an error may occur due to the flatness of the support substrate (not shown) on which the load sensors 120a to 120d are installed and the surface panel 110 that receives the input load and installation variations. Therefore, it is necessary to correct these variations when calculating the input position coordinates. Therefore, input position coordinates are accurately calculated by multiplying the load data detected by the load sensors 120a to 120d by the X position coefficient and the Y position coefficient corresponding to the load sensors 120a to 120d.

  However, as shown in FIG. 10B, when the sensor coordinate system 131 is rotated with the rotation of the input device 101, the relative positions of the sensor coordinate system 131 and the load sensors 120a to 120d change. End up. That is, the X position coefficient and the Y position coefficient necessary for calculating the input position coordinates change, and a deviation occurs between the actually input position and the calculated input position coordinates, so that the function as the input device 101 is achieved. Will be damaged. In addition, when this deviation is corrected by calculation processing, it is necessary to perform correction every time the rotation angle of the input device 101 changes, which complicates the processing, and the processing circuit for that purpose becomes large. The problem arises.

  The present invention solves the above-described problem, prevents detection position shift of the input position coordinates, and can easily convert the input position coordinates to the coordinates of the display coordinate system even when the rotation angle of the front panel changes. The present invention relates to an input device using a load sensor and a coordinate conversion method thereof.

  An input device using a load sensor according to the present invention includes a front panel having a display area for visually recognizing images and character data, and a plurality of load sensors arranged to detect an input position input to the front panel. And a display coordinate system that defines a display direction of the image and character data in accordance with a rotation angle of the front panel, and a sensor coordinate system that defines an input position to the front panel. Input position calculating means for calculating input position coordinates in the sensor coordinate system from load data of the plurality of load sensors, and converting the input position coordinates to coordinates in the display coordinate system based on the rotation angle of the front panel. And a coordinate conversion means.

  According to this, even when the display coordinate system is rotated in accordance with the rotation of the front panel, the input position coordinates by the input operation are accurately calculated in the sensor coordinate system. The calculated input position coordinates are converted into coordinates in the display coordinate system based on the rotation angle of the front panel. In this way, it is possible to detect the display position coordinates of the display image or the like by matching the input position coordinates by the input operation.

  Therefore, the relative position between the sensor coordinate system and each load sensor does not change compared to the case where the input coordinate is detected by rotating the sensor coordinate system together with the rotation of the display coordinate system. It is possible to prevent the detection position deviation of the input position coordinates due to the occurrence. Further, since it is not necessary to perform correction processing such as variation of each load sensor every time the rotation angle of the front panel changes, it is possible to easily convert the input position coordinates to the coordinates of the display coordinate system.

  Further, it is preferable that the coordinate conversion unit reads a coordinate conversion parameter corresponding to the rotation angle of the front panel and converts the input position coordinates into the coordinates of the display coordinate system. According to this, it is possible to convert the input position coordinates into the coordinates of the display coordinate system by using a predetermined mathematical expression using the coordinate conversion parameters. Therefore, since the step of calculating the variable necessary for coordinate conversion every time the rotation angle of the front panel changes can be omitted, it is possible to simplify the processing in the coordinate conversion means and perform coordinate conversion easily.

  Furthermore, according to the input device using the load sensor of the present invention, the X position coefficient and the Y position coefficient necessary for calculating the input position coordinates are set to a minimum of 2 using a plurality of load measurement data at the time of initial setting. It is preferable to obtain by multiplication. In this way, it is possible to improve the input position detection accuracy by obtaining correction coefficients such as characteristic variations and installation variations of each load sensor in advance at the time of initial setting and applying them in the input position calculation means.

  In the input device using the load sensor according to the present invention, the load sensor includes a sensor substrate and a plurality of piezo elements provided on the sensor substrate, and the displacement amount of the sensor substrate due to an input operation. Is preferably detected by the piezo element. According to this, since the load sensor can be downsized, it is advantageous for narrowing the frame of the input device.

  In the input device using the load sensor according to the present invention, the display area is formed in a substantially rectangular shape having four sides, and the plurality of load sensors are located at substantially the center of each side of the display area. It is preferable that they are respectively arranged on the outer periphery of the region. With such an arrangement, it is possible to improve the sensor output of each load sensor with respect to the input operation.

The input coordinate conversion method of the input device using the load sensor of the present invention is:
a) calculating input position coordinates in the sensor coordinate system from load data of the plurality of load sensors;
b) converting the input position coordinates of the sensor coordinate system into coordinates of the display coordinate system based on the rotation angle of the front panel.

  According to this, even when the display coordinate system rotates with the rotation of the front panel, the input position coordinates by the input operation are accurately calculated in the sensor coordinate system. The calculated input position coordinates are converted into coordinates in the display coordinate system based on the rotation angle of the front panel. In this way, it is possible to detect by matching the input position coordinates by the input operation with respect to the display coordinates of the display image or the like.

  Therefore, the relative position between the sensor coordinate system and each load sensor does not change compared to the case where the input coordinate is detected by rotating the sensor coordinate system together with the rotation of the display coordinate system. It is possible to prevent the detection position deviation of the input position coordinates due to the occurrence. Further, since it is not necessary to perform correction processing such as variation of each load sensor every time the rotation angle of the front panel changes, it is possible to easily convert the input position coordinates to the coordinates of the display coordinate system.

  According to the coordinate conversion method of the input device using the load sensor of the present invention, in the step b), the coordinate conversion parameter corresponding to the rotation angle of the surface panel is read, and the input position coordinates are converted into the display coordinate system. It is preferable to convert to the above coordinates. According to this, it is possible to convert the input position coordinates into the coordinates of the display coordinate system by using a predetermined mathematical expression using the coordinate conversion parameters. Therefore, since the step of calculating the variable necessary for coordinate conversion every time the rotation angle of the front panel changes can be omitted, it is possible to simplify the processing in the coordinate conversion means and perform coordinate conversion easily.

  According to the input device using the load sensor and the input coordinate conversion method of the present invention, the sensor coordinate system and each of the input coordinate system are compared with the case where the input coordinate is detected by rotating the sensor coordinate system together with the rotation of the display coordinate system. Since the relative position with respect to the load sensor does not change, it is possible to prevent the detection position shift of the input position coordinates due to the variation of each load sensor. Further, since it is not necessary to perform correction processing such as variations in the load sensor each time the rotation angle of the front panel changes, it is possible to easily convert the input position coordinates into the coordinates of the display coordinate system.

It is a top view of the input device using the load sensor in the embodiment of the present invention. It is sectional drawing when cut | disconnecting by the II-II line | wire of FIG. It is sectional drawing of the load sensor in this embodiment. The top view when the sensor board | substrate which comprises a load sensor is seen from the base board | substrate side is shown. It is a top view for demonstrating a display coordinate system and a sensor coordinate system when the input device of this embodiment is rotated. It is a flowchart figure which shows operation | movement of the input device in this embodiment. It is a block diagram of the input device in this embodiment. It is a table | surface which shows an example of the coordinate transformation parameter read in step ST6 of FIG. It is an initial measurement flowchart figure of the input device in this embodiment. It is a top view for demonstrating the subject in the input device using the load sensor of a prior art example.

  An input device 1 using a load sensor according to an embodiment of the present invention will be described with reference to the drawings. Note that each plan view and each cross-sectional view are schematically shown for easy viewing, and the ratio of dimensions is changed as appropriate.

  FIG. 1 is a plan view when the input device 1 is viewed from the input surface side, and is schematically shown through. FIG. 2 shows a cross-sectional view of the input device 1 taken along the line II-II in FIG.

  As shown in FIGS. 1 and 2, the input device 1 according to the present embodiment includes a plurality of load sensors 20 a to 20 d that can detect a load and a front panel 10. As shown in FIG. 2, the input device 1 is disposed on the display surface side of a display device 17 such as a liquid crystal panel or an OLED (Organic light emitting diode) panel, and is used as a display unit of a portable information terminal such as a cellular phone.

  The front panel 10 is formed from a transparent resin substrate such as PC (polycarbonate) or PMMA (polymethyl methacrylate resin) or a glass substrate, and constitutes an input surface for performing an input operation. As shown in FIG. 1, a rectangular display area 11 is provided on the front panel 10, and a user can visually recognize a display image, character data, and the like from the display device 17 through the display area 11.

  As shown in FIG. 2, a plurality of load sensors 20 a to 20 d (only 20 a and 20 c are shown in FIG. 2) are installed on the support substrate 13 so that the load position applied to the front panel 10 can be detected. It is arranged on the back side of the panel 10 (display device 17 side). Thereby, when an arbitrary portion of the input surface of the front panel 10 is pressed during an input operation, a load is applied to the plurality of load sensors 20a to 20d according to the input position, and load data is output respectively. Become. As the support substrate 13, a light-transmitting substrate can be used similarly to the front panel 10, and a window-like hole can be formed at a location facing the display region 11 as necessary.

  As shown in FIG. 1, a colored decoration area 12 is provided on the outer periphery of the rectangular display area 11. In the present embodiment, the plurality of load sensors 20 a to 20 d are respectively disposed in the decoration area 12 located at the approximate center of each side of the rectangular display area 11. By arranging in this way, the load applied to the front panel 10 can be detected well. That is, the front panel 10 is configured to have a rigidity that can support the pressing in the input operation, but is easily bent at a place where the load sensors 20 a to 20 b are not provided on the back surface of the front panel 10. Therefore, for example, when the load sensors 20a to 20b are provided at the corners, the vicinity of the central part of the side is particularly easily bent, so that even if the vicinity of the central part of the display region 11 is pressed, the load is not transmitted well to the load sensors 20a to 20d. In some cases, the sensor output may decrease. On the other hand, the load applied to the front panel 10 is good for each load sensor 20a to 20d by forming the load sensors 20a to 20d near the center of each side like the input device 1 of the present embodiment. Thus, the sensor output can be improved. The position and number of load sensors are not limited to this.

  In the decorative region 12, a colored decorative layer (not shown) is formed by a printing method such as a screen printing method or an ink jet printing method. Thereby, the decoration area | region 12 is shielded and it can prevent that each load sensor 20a-20d is visually recognized by a user.

  3 is a cross-sectional view of the load sensor 20a, and FIG. 4 is a plan view when viewed from the back side of the sensor substrate 22. 3 shows the configuration of the load sensor 20a, the load sensors 20b to 20c also have the same configuration and function.

  As illustrated in FIG. 3, the load sensor 20 a includes a sensor substrate 22, a base substrate 21, and a pressure receiving unit 24.

  The sensor substrate 22 and the base substrate 21 are bonded by bonding a sensor substrate side support portion 27a and a base substrate side support portion 27b. The sensor substrate 22 and the base substrate 21 are joined so as to have a predetermined space. A displacement portion 25 that can be displaced in the thickness direction is formed on the sensor substrate 22, and a pressure receiving portion 24 that protrudes upward is formed on the upper surface of the displacement portion 25. As shown in FIG. 4, a plurality of piezo elements 23 are formed on the back surface of the sensor substrate 22 as strain detection elements. The plurality of piezo elements 23 are connected by a wiring section 26 so as to form a bridge circuit.

  When a load is applied to an arbitrary portion of the front panel 10 during the input operation of the input device 1, the load is applied to the pressure receiving portions 24 of the load sensors 20 a to 20 d arranged on the back surface of the front panel 10. Thereby, the displacement part 25 is displaced in the thickness direction of the sensor substrate 22, and the electric resistance value of each piezo element 23 changes according to the amount of displacement. Due to the change in the electric resistance value of each piezo element 23, the midpoint potential of the bridge circuit constituted by each piezo element 23 changes and is taken out as a sensor output. As shown in FIG. 3, the sensor board side electrical connection portion 28a is connected to the base board side electrical connection portion 28b, and the sensor output is sent to the external control unit 15 (not shown) via the base substrate side electrical connection portion 28b. Is output. Then, the input position coordinates are calculated based on the sensor output data of the load sensors 20a to 20d.

  The load sensors 20a to 20d can be manufactured by a semiconductor process, and the sensor substrate 22, the base substrate 21, and the pressure receiving unit 24 are made of a silicon substrate. Due to variations in the manufacturing process, the output characteristics of the load sensors 20a to 20d have variations. In addition, errors may occur due to warpage or distortion of the front panel 10 and the support substrate 13, the installation method of the load sensors 20a to 20d, and the like.

  Therefore, when calculating the input position coordinates, it is necessary to correct variations in output characteristics of the load sensors 20a to 20d. Therefore, the input position coordinates are calculated by multiplying the data of each of the load sensors 20a to 20d by the X position coefficient and the Y position coefficient corresponding to each variation.

  FIG. 5 is an explanatory diagram showing a relationship between the display coordinate system 30 and the sensor coordinate system 31 and the input device 1 when the rotation angle of the input device 1 changes. The display coordinate system 30 is a coordinate system that defines the display direction of display images, character data, and the like according to the rotation of the front panel 10, and the sensor coordinate system 31 is a coordinate system that defines the input position to the front panel 10. . FIG. 5A shows an initial state in which the direction of the input device 1 substantially matches the direction of gravity. FIG. 5B shows a state in which the input device 1 is rotated about 90 ° counterclockwise, and FIGS. 5C and 5D show cases where the input device 1 is rotated about 180 ° and about 270 °, respectively. Show.

  As shown in FIG. 5A, in the initial state, the display coordinate system 30 and the sensor coordinate system 31 coincide with each other, and both the display coordinate origin 30a and the sensor coordinate origin 31a are, for example, the upper left corner of the display area 11. Is set in the department. In this case, the detection position shift of the input position coordinate during the input operation with respect to the display position coordinate of the display image or menu selection item does not occur, and the input operation can be performed without any problem.

  However, when the rotation angle of the front panel 10 is changed as shown in FIGS. 5B to 5D, a display image, character data, etc. are displayed in a fixed direction for the user. The coordinate system 30 rotates with respect to the front panel 10. That is, even if the input device 1 is rotated by about 90 ° (FIG. 5B), about 180 ° (FIG. 5C), and about 270 ° (FIG. 5D), the display coordinate origin 30a remains the The coordinates are converted so as to be located at the upper left of the display area 11 when viewed from above. Thereby, an image or the like is displayed in an appropriate direction for the user regardless of the rotation angle of the front panel 10.

  On the other hand, the relative position of the sensor coordinate system 31 with respect to the load sensors 20a to 20d does not change even when the front panel 10 rotates. For example, as shown in FIG. 5B, when the front panel 10 is rotated by 90 °, the sensor coordinate system 31 is also rotated by 90 °. Accordingly, since the display coordinate system 30 and the sensor coordinate system 31 do not coincide with each other due to the rotation of the front panel 10, a deviation occurs between the display position coordinates and the input position coordinates.

  For example, similarly to the input device 101 of the conventional example shown in FIG. 10, when the sensor coordinate system 31 is rotated with respect to the front panel 10 together with the rotation of the display coordinate system 30, the sensor coordinate system 31 and the display coordinate system 30 The gap is gone. However, as described above, the calculation of the input position coordinates is performed by multiplying the X position coefficient and the Y position coefficient for correcting variations and the like of the load sensors 20a to 20d. Therefore, each time the sensor coordinate system 31 rotates with respect to each of the load sensors 20a to 20d, it is necessary to newly set a correction coefficient, the processing time increases, and the circuit required for the processing also increases. The problem that it will end up arises. In addition, when the correction coefficient is not set when the sensor coordinate system 31 is rotated, the calculation deviation of the input position coordinates becomes large, and the function as the input device 1 may be impaired.

  Hereinafter, the input coordinate conversion method in the input device 1 of this embodiment is demonstrated based on drawing. In FIG. 6, the flowchart of the input coordinate transformation in the input device 1 of this embodiment is shown. FIG. 7 shows a block diagram of the input device 1.

  In step ST <b> 1 shown in FIG. 6, the user performs an input operation by applying a load to an arbitrary portion of the front panel 10. Thereby, the load according to the input position and the input load amount is applied to each of the load sensors 20a to 20d arranged on the back surface of the front panel 10.

  In step ST2, the sensor output data respectively detected by each load sensor 20a-20d is sent to the control part 15 shown in FIG. 7, and is acquired as load data. The control unit 15 is composed of an IC (Integrated Circuit) that performs various processes, and may be composed of a plurality of ICs depending on the function to be processed and the purpose.

Next, in step ST3, input coordinates in the sensor coordinate system 31 are calculated based on each load data. When the load data detected by each of the load sensors 20a to 20d is DatA, DatB, DatC, and DatD, the input position coordinates in the sensor coordinate system 31 are (Xs, Ys), and the total load is Z, the following equation Is calculated by Ax to Dx and Ay to Dy are an X position coefficient and a Y position coefficient for correcting variations of the load sensors 20a to 20d.
Xs = (Ax · DatA + Bx · DatB + Cx · DatC + Dx · DatD) / Z
Ys = (Ay · DatA + By · DatB + Cy · DatC + Dy · DatD) / Z
Z = DatA + DatB + DatC + DatD

  In the present embodiment, as shown in FIGS. 5B to 5D, the relative positions of the sensor coordinate system 31 and the load sensors 20a to 20d change even when the front panel 10 is rotated. Therefore, the input coordinates in the sensor coordinate system 31 can be calculated by the above formula. Further, the X position coefficient and Y position coefficient obtained in the initial state can be used as they are, and the step of obtaining the X position coefficient and Y position coefficient can be omitted every time the rotation angle of the front panel 10 changes. The input position coordinates can be calculated easily.

  Further, when the rotation angle of the front panel 10 is changed as shown in FIG. 5B to FIG. 5D, the relative position of the sensor coordinate system 31 with respect to the load sensors 20a to 20d does not change. On the other hand, the display coordinate system 30 rotates according to the rotation of the front panel 10. For this reason, since the sensor coordinate system 31 and the display coordinate system 30 are displaced, the input position coordinates in the sensor coordinate system 31 and the display position coordinates in the display coordinate system 30 do not match. In the input device 1 of this embodiment, the input position coordinates of the sensor coordinate system 31 calculated in step ST3 can be matched by converting the input position coordinates to the coordinates of the display coordinate system 30 in step ST6.

  First, in step ST4 shown in FIG. 6, the rotation angle data of the front panel 10 is acquired from the rotation detector 14 shown in FIG. The rotation detection unit 14 is not limited to being installed integrally with the front panel 10, but is substantially rotated by the surface panel 10 such as being arranged on a circuit board such as a printed circuit board connected to the input device 1 or the display device 17. It only has to be arranged so that angle data can be detected.

  The rotation detection unit 14 can use a sensor such as an acceleration sensor, and can detect the rotation angle of the surface panel 10 by detecting the direction of the surface panel 10 with respect to the direction of gravity. Or when rotating the surface panel 10 with respect to the housing | casing of a portable apparatus, the rotation angle of the surface panel 10 with respect to a housing | casing can be detected using a mechanical or electrical switch as the rotation detection part 14. FIG. .

  Next, in step ST5, a coordinate conversion parameter corresponding to the rotation angle of the front panel 10 is acquired. The coordinate conversion parameters are parameters required at the time of input position coordinate conversion in step ST6, which will be described later. As shown in FIG. 8, the values of the coordinate conversion parameters (θ, Xp, Yp) corresponding to the rotation angle are sent to the control unit 15. Pre-saved. Xp_max and Yp_max in the table indicate the maximum widths in the X direction and the Y direction of the display area 11 of the front panel 10. For example, as shown in FIG. Assuming the upper left corner, the coordinates of the lower right corner are (Xp_max, Yp_max). Further, “rotation index” 0 to 3 shown in the table of FIG. 8 are respectively set corresponding to FIGS. 5 (a) to 5 (d). For example, when the rotation angle of the front panel 10 is in the state as shown in FIG. 5B, the coordinate conversion parameters corresponding to “rotation index” = 1 shown in the table of FIG. 8, that is, (θ, Xp, Yp ) = (90, Xp_max, 0).

  In step ST6, the input position coordinates in the sansa coordinate system 31 can be converted into the coordinates of the display coordinate system 30 by [Equation 1] shown below. In step ST6, using the input position coordinates (Xs, Ys) obtained in step ST3 and the coordinate conversion parameters (θ, Xp, Yp) obtained in step ST5, the coordinates of the display coordinate system 30 can be easily obtained. It is possible to convert. Thereby, the input position coordinates (Xs, Ys) in the sensor coordinate system 31 are converted into the input position coordinates (Xt, Yt) in the display coordinate system 30. For the total load data Z, the value obtained in step ST3 is used as it is.

  In step ST6, as shown in [Equation 1], X position coefficients (Ax to Dx) and Y position coefficients (Ay to Dy) for correcting the influence of variations and the like of the load sensors 20a to 20d are newly set. It is not necessary to calculate and use for the coordinate conversion formula. Therefore, it is not necessary to calculate a correction coefficient every time the rotation angle of the front panel 10 changes, and coordinate conversion can be performed in a short time. In addition, an increase in the size of the processing circuit in the control unit 15 can be suppressed.

  Note that steps ST4 and ST5 can be executed in parallel with steps ST2 and ST3, as shown in FIG. When the coordinate conversion is performed by calculating the correction coefficient according to the change in the rotation angle of the front panel 10 as in the prior art, the coordinate conversion process is complicated, and parallel processing is difficult, so the processing time increases. Resulting in. On the other hand, in the input device 1 of the present embodiment, parallel processing is possible, and coordinate conversion processing is completed in a short time, so that a comfortable input operation can be performed.

  Next, in step ST7, the screen display of the display device 17 is updated based on the input position coordinates (Xt, Yt) converted into the display coordinate system 30. In this process, the input position coordinate data (Xt, Yt) and the total load data Z are transmitted to the image processing unit 16 shown in FIG. 7, and the screen of the display device 17 is updated. Note that it is not always necessary to transmit all the data to the image processing unit 16, and a part of the data may be transmitted as necessary.

  After step ST7, when the input operation is continued, the process is repeated from step ST1, and when the input operation is not performed, the process is ended (step ST8).

  FIG. 9 shows an initial measurement flowchart for obtaining the X position coefficient and the Y position coefficient for correcting the influence of variations and the like of the load sensors 20a to 20d. Since this initial measurement only needs to be performed once, it is performed before shipment after the input device 1 is assembled. Or the user who purchased the portable apparatus etc. with which the input device 1 was integrated may implement first.

  In step ST11 of FIG. 9, as the initial offset correction, zero point correction is performed on the output data of the load sensors 20a to 20d in the initial state. This is a process of correcting the zero point for the load applied to each of the load sensors 20a to 20d in the initial state. Thereby, the output dispersion | variation of each load sensor 20a-20d in an initial state and the dispersion | variation in the state of installation with the surface panel 10 can be reset.

  Next, after step ST12, a data acquisition loop is executed. In step ST13, a certain load is applied to a predetermined position of the display area 11, for example, (Xs, Ys) = (0, 0). And the output data (DatA1, DatB1, DatC1, DatD1) of each load sensor 20a-20d at that time is acquired (step ST14).

  Such data acquisition processing (ST13 to ST14) is repeated at different positions in the sensor coordinate system 31 (step ST15). Since the input position coordinate (Xs, Ys) is a predetermined position, there are four variables of output data (DatA, DatB, DatC, DatD) of the load sensors 20a to 20d. Therefore, a linear equation with four variables can be established by acquiring data at at least four locations. Thereby, the X position coefficient (Ax, Bx, Cx, Dx) and the Y position coefficient (Ay, By, Cy, Dy) can be obtained using the least square method.

  The X position coefficient and Y position coefficient obtained by the initial measurement flow shown in FIG. And it is used in the calculation process of the input position coordinate of step ST3 shown in FIG. Thereby, the dispersion | variation etc. of each load sensor 20a-20d are correct | amended, and the detection accuracy of the input position coordinate in the sensor coordinate system 31 can be improved.

  Further, when the input position coordinates in the sensor coordinate system 31 are converted into the coordinates of the display coordinate system 30 (step ST6), the X position coefficient and the Y position coefficient are not required as shown in [Equation 1]. Therefore, it is not necessary to perform a data acquisition loop (steps ST12 to ST15) as shown in FIG. 9, for example, according to the rotation angle of the front panel 10, and coordinate conversion can be performed with a simple calculation process.

DESCRIPTION OF SYMBOLS 1 Input device 10 Front panel 11 Display area 12 Decoration area 13 Support board 14 Rotation detection part 15 Control part 16 Image processing part 17 Display apparatus 20a, 20b, 20c, 20d Load sensor 21 Base board 22 Sensor board 23 Piezo element 24 Pressure receiving Section 25 Displacement section 30 Display coordinate system 30a Display coordinate origin 31 Sensor coordinate system 31a Sensor coordinate origin

Claims (7)

A front panel having a display area for visually recognizing images and character data;
A plurality of load sensors arranged to detect an input position input to the front panel,
A display coordinate system that defines a display direction of the image and character data according to a rotation angle of the front panel, and a sensor coordinate system that defines an input position to the front panel,
Input position calculating means for calculating input position coordinates in the sensor coordinate system from load data of the plurality of load sensors, and converting the input position coordinates into coordinates in the display coordinate system based on the rotation angle of the front panel. And an input device using a load sensor.   2. The load according to claim 1, wherein the coordinate conversion unit reads a coordinate conversion parameter corresponding to the rotation angle of the front panel and converts the input position coordinates into the coordinates of the display coordinate system. 3. An input device using a sensor.   3. The X-position coefficient and Y-position coefficient necessary for calculating the input position coordinates are obtained by a least square method using a plurality of load measurement data at the time of initial setting. An input device using the described load sensor.   The load sensor is configured to include a sensor substrate and a plurality of piezoelectric elements provided on the sensor substrate, and the displacement amount of the sensor substrate due to an input operation is detected by the piezoelectric element. An input device using the load sensor according to any one of claims 1 to 3.   The display area is formed in a substantially rectangular shape having four sides, and the plurality of load sensors are respectively arranged on outer peripheries of the display area located substantially at the center of each side of the display area. An input device using the load sensor according to any one of claims 1 to 4. A front panel having a display area for visually recognizing images and character data, and a plurality of load sensors arranged to detect an input position input to the front panel, the rotation angle of the front panel An input coordinate conversion method for an input device using a load sensor having a display coordinate system that defines a display direction of the image and character data according to the position and a sensor coordinate system that defines an input position to the front panel. ,
a) calculating input position coordinates in the sensor coordinate system from load data of the plurality of load sensors;
b) converting the input position coordinate of the sensor coordinate system into the coordinate of the display coordinate system based on the rotation angle of the front panel; and an input device using a load sensor, Input coordinate conversion method. The load according to claim 6, wherein in the step b), a coordinate conversion parameter corresponding to the rotation angle of the front panel is read, and the input position coordinates are converted into the coordinates of the display coordinate system. An input coordinate conversion method for an input device using a sensor.