JP2012098833A - Electronic writing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform high-precision position detection over a wide range of a detection coil section and to make arithmetic processing simple and prompt.SOLUTION: An electronic writing device includes a detection coil section 101 including an even-numbered X main detection coil Xk and odd-numbered X auxiliary detection coils Xs having a smaller width direction dimension than that of the X main detection coil Xk among (n) detection coils along an X axis direction, and a ROM 80b which stores a position coordinate table corresponding to a combination curve G which is produced by appropriately combining characteristic curves Tk and Ts of a peak voltage value Ep and two peak auxiliary voltage values E1 and E2 in such a manner that a cross point Pa is out of the detection coil section 101. The main detection coil Xk which detects the maximum peak voltage value Ep is used as a peak coil and the two auxiliary detection coils Xs at both sides of the peak coil are used as peak auxiliary coils, and positional information of an electronic pen 2 is calculated using the peak voltage value Ep and the peak auxiliary voltage values E1 and E2.

Description

  The present invention relates to an electronic writing apparatus capable of inputting data corresponding to a user's handwritten writing content.

  2. Description of the Related Art Conventionally, electronic writing devices that can input data corresponding to user-written writing contents have been developed and are widely used. Such an electronic writing device is provided with a group of loop coils arranged in parallel with each other in the X direction and the Y direction which are orthogonal to each other. And the position detection area of the detection coil part which detects the position of the electronic writing instrument which functions as a position indicator is comprised by the said loop coil group. When the electronic writing instrument is placed in a position detection area on the electronic writing apparatus, it generates alternating magnetic field lines from its tip. The CPU of the electronic writing device detects the signal level generated by the alternating magnetic field lines in a plurality of loop coils in the vicinity where the electronic writing tool is placed from the loop coil group, and the distribution of these detected signal levels The XY coordinate value of the position indicated by the electronic writing instrument is obtained as position information.

  In such an electronic writing apparatus, generally, one loop coil (hereinafter referred to as a peak coil) that detects the largest signal level closest to the electronic writing instrument and two loop coils located on both sides thereof are used. Position information with high accuracy is obtained using three coils. However, this position information calculation algorithm cannot be applied when the outermost loop coil in the X direction or the Y direction becomes a peak coil because there is no outer loop coil. As a result, in the outer edge portion of the position detection area, an invalid area is generated in which the position information of the electronic writing instrument cannot be accurately detected while the loop coil is arranged.

  A method for eliminating such an invalid area has been proposed in the past (for example, see Patent Document 1). In this prior art, among the many loop coils provided, loop coils located at the outer edge portion and in the vicinity thereof have a smaller width than other loop coils. Then, position information of the electronic writing instrument is obtained from a distribution of signal levels detected by a predetermined number of outer loop coils including them. Thereby, the range which the loop coil located in an outer edge part shares the said alternating magnetic force line with the loop coil inside it can be expanded, and the said invalid area | region can be reduced.

Japanese Patent Laid-Open No. 3-201018

  However, in the above prior art, it is necessary to prepare a position detection algorithm that is different in the center portion and the outer edge portion in the same position detection area. In this case, not only the processing by switching the algorithm becomes complicated, but also the influence of each algorithm on the same noise is different, so an error that is difficult to correct near the boundary between the central portion and the outer edge portion occurs. End up.

  An object of the present invention is to provide an electronic writing apparatus that can perform highly accurate position detection over a wide range of a detection coil section and that can simplify and speed up arithmetic processing.

In order to achieve the above object, the first invention has a signal generating means having a coil for applying a magnetic field, and a writing signal for position detection for inputting data corresponding to writing contents to a writing object. Can be received by the signal generating means and transmitted from the electronic writing instrument, and can output n output values derived from the writing signal along a predetermined direction (n is 3 or more) At least one for detecting a peak output value serving as a reference for position detection in which the n coils are arranged in an even number out of the n arrays along the predetermined direction. A detection coil unit comprising: one main detection coil; and a plurality of auxiliary detection coils arranged oddly among n arrays along the predetermined direction and having a size smaller than the main detection coil in the predetermined direction; The brush Based on the reception result in the detection coil unit including the output value of the signal, the calculation means for calculating the position information of the electronic writing instrument and the output value of the at least one main detection coil arranged in the even number are obtained. Of the at least one main detection coil whose output value is acquired by the primary output acquisition means, a main output coil that detects the peak output value that is the maximum output value is a peak coil. And a peak auxiliary coil specifying means for specifying two auxiliary detection coils adjacent to both sides along the predetermined direction of the peak coil specified by the peak coil specifying means as peak auxiliary coils, The output values of the two peak auxiliary coils specified by the peak auxiliary coil specifying means are acquired. Secondary output acquisition means, and the calculation means includes the peak output value from the peak coil specified by the peak coil specifying means, and the two peak values specified by the peak auxiliary coil specifying means. An electronic writing device that acquires the position information of the electronic writing instrument using a peak auxiliary output value from a peak auxiliary coil, wherein the output value is on one axis and the position information is on the other axis. A composite curve obtained by appropriately combining a plurality of characteristic curves representing correlation characteristics between the peak output value and the peak auxiliary output values of the two peak auxiliary coils and the position information, or the composite curve A corresponding data group, the separation distance in the predetermined direction from the center position of the peak coil to the position of the electronic writing instrument, and the electronic Formula (Ep-E1) / (Ep-E2) when the writing instrument is positioned at the separation distance
However,
Ep: Peak voltage value E1: Larger peak auxiliary output value E2: Correlation information including the one composite curve or the data group representing the correlation characteristic with the reference value calculated by the smaller peak auxiliary output value Correlated storage means is stored, and the detection coil unit includes the n coils so that Ep> E2 on the composite curve applied within the coil position range where the n coils are arranged. Is arranged.

  In the electronic writing device according to the first invention of the present application, when the user performs writing on the writing object using the electronic writing tool, the writing operation is performed based on the writing signal generated by the signal generating means and transmitted from the electronic writing tool. A movement trajectory is detected. That is, the electronic writing device according to the first aspect of the present invention is provided with a detection coil portion comprising a plurality of coils. Based on the reception result of the writing signal from the electronic writing instrument in the plurality of coils, the calculating means performs a predetermined calculation to calculate the position information of the electronic writing instrument.

  In order to calculate the position information, the detection coil unit includes at least one main detection coil and a plurality of auxiliary detection coils. In the detection coil section, n coils that are odd numbers of 3 or more are arranged along a predetermined direction, the main detection coil is arranged in an even number, and the auxiliary detection coil is arranged in an odd number. First, the calculation means is connected to the main detection coil by the primary connection means. And a peak coil specific | specification means specifies the peak coil which gives the largest peak output value among the connected main detection coils. Thereby, the main detection coil closest to the electronic writing instrument is specified as the peak coil. Thereafter, the peak auxiliary coil specifying means specifies two peak auxiliary coils adjacent to both sides of the specified peak coil. Thereafter, the calculation means is connected to the two peak auxiliary coils by the secondary connection means. Thereby, the calculation means calculates the position information of the electronic writing instrument based on the output values from the total of three coils including the identified one peak coil and two adjacent peak auxiliary coils.

Here, in the first invention of this application, the correlation storage means stores correlation information for use in the calculation of the position information. First, a characteristic curve representing a correlation characteristic between an output value and position information, which is expressed with an output value on one axis and position information on the other axis, is calculated in advance for each coil such as the main detection coil and the auxiliary detection coil. ing. The correlation information includes one composite curve obtained by appropriately combining the plurality of characteristic curves. This composite curve is calculated by the formula (Ep−E1) / (Ep−E2) when the distance between the center position of the peak coil and the position of the electronic writing instrument in the predetermined direction and the electronic writing instrument is positioned at the separation distance.
However,
Ep: Peak voltage value E1: Larger peak auxiliary output value E2: A curve representing a correlation characteristic with a reference value calculated by a smaller peak auxiliary output value. As a result, the calculation means calculates the position information of the electronic writing instrument using a combined curve obtained by combining characteristic curves relating to a total of three coils including the peak coil and two adjacent peak auxiliary coils. Note that the correlation storage means may store data groups corresponding to them instead of the composite curve as the correlation information, and the calculation means may calculate using the data groups.

  As described above, in the first invention of the present application, even-numbered main detection coils and odd-numbered auxiliary detection coils are alternately arranged along a predetermined direction to calculate position information. At this time, the dimension of the auxiliary detection coil in the predetermined direction is smaller than the dimension of the main detection coil. By reducing the dimensions of the auxiliary detection coils arranged at both ends of the array, it is possible to reduce the undetectable range at both ends of the detection coil unit and perform highly accurate position detection over a wide range. In addition to the auxiliary detection coils arranged at both ends of the array, if there are auxiliary detection coils located in the middle part of the other arrays, the dimensions thereof are also the same as the auxiliary detection coils at both ends. Make it smaller. That is, unlike the conventional method in which only the coils at both ends are made smaller by making the dimensions in the predetermined direction of all the auxiliary detection coils common, the composite curve stored in the correlation storage means is shared by all the auxiliary detection coils. It can be set as an aspect.

  Here, in the first invention of the present application, the above-mentioned composite curve and the corresponding data group do not diverge, that is, no divergence portion is generated in which an indefinite output value is associated with one position information. In addition, n coils of the detection coil section are arranged. That is, in the detection coil unit, the n coils are arranged so that Ep> E2 on the composite curve applied within the coil position range where the n coils are arranged. As a result, when the calculation means calculates using the composite curve, the corresponding position information must be unique for the peak output value from the one peak coil and the peak auxiliary output value from the two peak auxiliary coils. Can be obtained. In addition, it is not necessary to use separate algorithms for both ends of the array and the other portions as in the above-described conventional method, and computation can be performed using only one common algorithm. As a result, it is possible to simplify and speed up the processing in the calculation of the calculation means.

  As a result, in the first invention of the present application, highly accurate position detection can be performed over a wide range of the detection coil section, and calculation processing can be simplified and speeded up.

  According to a second aspect of the present invention, in the first aspect, the output value of the data group in which the position information is in the vicinity of both ends of the coil position range is selected from the data group corresponding to the composite curve. The n coils are arranged so as to converge to a predetermined value or less.

  Thereby, the divergence of the composite curve and the corresponding data group is prevented, and the corresponding position information is always uniquely obtained for the output value from one main detection coil and the output value from the two auxiliary detection coils. be able to.

  According to a third invention, in the first or second invention, the dimension of the auxiliary detection coil in the predetermined direction is not less than 1/3 and not more than 1/2 of the dimension of the main detection coil in the predetermined direction. And

  As a result, it is possible to reliably reduce the undetectable range at both ends of the detection coil unit and perform highly accurate position detection over a wide range.

  In a fourth invention according to any one of the first to third inventions, the dimension in the predetermined direction is a dimension in the width direction of the coil, and the dimensions in the width direction of the main detection coil are all the same. The auxiliary detection coils are all the same in the width direction.

  In this way, by making the width dimension as the predetermined direction common to all the main detection coils and all the auxiliary detection coils, the output change on the electronic writing device side, the change in the environment around the device, etc. Even when the output value from the detection coil section fluctuates due to some circumstances, the influence of the fluctuation occurs equally in all the auxiliary detection coils. As a result, unlike the conventional method in which only the coils at both ends are made smaller, the influence of the above-described variation differs between the both ends and the intermediate portion, and the overall detection accuracy does not deteriorate. Since the calculation can be performed using only one common algorithm, it is possible to simplify and speed up the processing in the calculation of the calculation means.

  According to a fifth invention, in the fourth invention, the calculation means calculates the reference value from the calculation formula using the actually detected peak output value and the two peak auxiliary output values. Based on the correlation information, a larger peak auxiliary output value is detected from the separation distance conversion means for converting the reference value calculated by the reference value calculation means to the separation distance and the center of the peak coil. Position information determination means for determining, as the position information of the electronic writing instrument, a position separated by the separation distance converted by the separation distance conversion means toward the peak auxiliary coil.

Thereby, if the actual measurement value of the peak output value and the two peak auxiliary output values can be detected, the reference value calculated based on these can be converted into the separation distance using the correlation information,
The position information of the electronic writing instrument can be calculated easily and with high accuracy.

  According to the present invention, position detection with high accuracy can be performed over a wide range of the detection coil section, and calculation processing can be simplified and speeded up.

It is an external appearance perspective view, a conceptual top view, and a conceptual side view showing the mode at the time of use of the handwriting input device of one embodiment of the present invention. It is a functional block diagram showing the functional structure of a handwriting input device. It is a notional top view showing the arrangement composition of the X detection coil part in an embodiment. It is a figure showing the change characteristic of the detection voltage in a sense coil. It is a conceptual top view showing each characteristic curve and a synthetic | combination curve in the comparative example of the X detection coil part which made ratio of the width direction dimension between coils 1. FIG. 4 is a conceptual plan view showing each characteristic curve and composite curve in the arrangement configuration example of the X detection coil unit shown in FIG. 3. It is a flowchart showing the content of the control processing performed with CPU of a coordinate detection apparatus. It is a conceptual top view showing each characteristic curve and synthetic curve in the example of arrangement composition of the X detection coil part which made the ratio of the width direction size between coils 1/4. It is a figure showing the relationship of the ratio of the width direction dimension of the X auxiliary | assistant detection coil with respect to X main detection coil, and an invalid area | region width | variety. It is a conceptual top view showing each characteristic curve and a synthetic | combination curve in the example of arrangement | positioning structure of the X detection coil part which made ratio of the width direction dimension between coils 1/3. It is a conceptual top view explaining the optimal value of the ratio of the width direction dimension between coils.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  A handwriting input device 1 that is an electronic writing device of the present embodiment includes a coordinate detection device 3 as shown in FIG. The user has an electronic pen 2 as an electronic writing instrument. In addition to the function as a writing instrument, the electronic pen 2 functions as input means for input positional information, that is, coordinate data.

  As shown in FIGS. 1 (a), 1 (b), and 1 (c), the coordinate detection device 3 has a predetermined direction (FIG. 1 (b)) so as to substantially cover the notebook 30 that is a writing object. The sheet body 10 is configured in a shape that can be spread in the middle and left and right directions. In the following description, the spread direction is defined as the X-axis direction (left and right direction in FIG. 1B) with reference to the state in which the sheet body 10 is installed in the above-described spread shape (state in FIG. 1B). The XY coordinate system is defined with the direction orthogonal to the X-axis direction as the Y-axis direction (vertical direction in FIG. 1B). The X-axis direction corresponds to a predetermined direction described in each claim.

  The sheet body 10 includes a bent portion 10T along the Y-axis direction at the center in the X-axis direction. The bent portion 10T is a portion that can be bent by the user. The sheet body 10 has a left-side sheet portion 10L positioned on one side (left side in FIG. 1B) across the bent portion 10T, and a right-side sheet portion 10R positioned on the other side (right side in FIG. 1B). It is divided into and. A left coil sheet 100L and a right coil sheet 100R are housed in the left seat part 10L and the right seat part 10R, respectively.

  And the notebook 30 of the shape which can be spread in the said X-axis direction is arrange | positioned so that it may overlap with the said sheet | seat body 10. FIG. Note that a notebook holding section 11 as shown in FIG. 1A may be provided on each of the left sheet section 10L and the right sheet section 10R. Thereby, the coordinate detection apparatus 3 can be integrated with the notebook 30 easily and reliably, and the handleability by the user can be improved.

  The user writes a desired handwritten character string or the like on the left writing surface 31 </ b> L or the right writing surface 31 </ b> R of the notebook 30 using the electronic pen 2. By moving the electronic pen 2 corresponding to the writing operation, stroke data corresponding to the written character string or the like is stored in the electronic file. At that time, actual writing is also performed on the left writing surface 31L and the right writing surface 31R of the notebook 30 using the ink provided in the electronic pen 2.

  When the user uses the handwriting input device 1, a power switch (not shown) provided in the electronic pen 2 is turned on. In this example, the electronic pen 2 generates and transmits an alternating magnetic field having a predetermined frequency as a position detection writing signal for inputting data corresponding to writing contents on the writing surface 31. As shown in FIG. 2, the electronic pen 2 includes a tip switch 42, an LC oscillation circuit 41, and a battery 43.

  The tip switch 42 is turned on when the user presses the tip 2 a of the electronic pen 2 against the writing surface 31 to write a character or the like using the electronic pen 2, and sends a command signal to the LC oscillation circuit 41. S0 is output. On the other hand, the tip switch 42 is turned off when the user stops writing of characters or the like and separates the tip 2 a of the electronic pen 2 from the writing surface 31. In this case, the command signal S0 is not output.

  The LC oscillation circuit 41 corresponds to signal generation means, and includes a capacitor and a coil (magnetic field applying coil; not particularly shown) (not shown). The capacitance of the capacitor varies depending on whether the tip switch 42 is on or off. The LC oscillation circuit is always supplied with electric power. When the tip switch 42 is turned on, the capacitance of the capacitor changes, and the LC oscillation circuit 41 can generate an induced electromotive force by a sense coil described later. An alternating magnetic field having the predetermined frequency (hereinafter, simply referred to as “magnetic field” as appropriate) is generated.

  The battery 43 always supplies power to the LC oscillation circuit 41 as described above.

  As shown in FIG. 2, the coordinate detection device 3 includes a left coil sheet 100L and a right coil sheet 100R, a microcomputer 80, a multiplexer 62 (hereinafter referred to as “MUX 62” as appropriate), an amplifier circuit 64, and a rectifier circuit. 66, flash memory 72, communication interface 74, and battery 21.

  The left coil sheet 100L and the right coil sheet 100R have substantially the same configuration, and both have a plurality of sense coils (see FIG. 3 described later) arranged in parallel with each other in the X-axis direction and the Y-axis direction. . Each sense coil is a loop coil that can receive the magnetic field generated by the electronic pen 2, and outputs a signal S 1 having a level corresponding to the relative position with the electronic pen 2.

  The microcomputer 80 includes a CPU 80a, a ROM 80b, a RAM 80c, and other A / D conversion function units, interrupt function units, and the like as one integrated circuit. The microcomputer 80 controls various processes executed by the coordinate detection device 3.

  Based on the coil selection signal S3 from the microcomputer 80, the MUX 62 sequentially selects one of the plurality of sense coils included in the left coil sheet 100L and the right coil sheet 100R. Then, the MUX 62 inputs the signal S1 generated by magnetic induction with the magnetic field generated from the LC oscillation circuit 41 of the electronic pen 2 in the selected loop coil, and outputs the corresponding signal S11 to the amplifier circuit 64. . Note that magnetic induction with the magnetic field generated from the electronic pen 2 substantially corresponds to reception of the magnetic field.

  The amplifier circuit 64 amplifies the signal S11 input from the MUX 62. The signal S13 amplified by the amplifier circuit 64 is input to the rectifier circuit 66.

  The rectifier circuit 66 amplitude-detects the signal S13 input from the amplifier circuit 64, smoothes it, and converts it into a DC signal. The signal S14 subjected to amplitude detection by the rectifier circuit 66 is input to the microcomputer 80.

  As described above, the microcomputer 80 has an A / D conversion function, and converts the input signal S14 after amplitude detection into a digital signal. At this time, the CPU 80a of the microcomputer 80 pre-calculates a position coordinate table (described later) and stores it in the ROM 80b as a correlation storage means. The microcomputer 80 calculates the coordinate data of the electronic pen 2, that is, the position information of the respective coordinate positions in the X-axis direction and the Y-axis direction, by applying the calculated position coordinate table to the digital signal. . The calculated coordinate data is stored in the flash memory 72. Details of this coordinate data calculation method will be described later.

  An electronic file is prepared in advance in the flash memory 72, and coordinate data calculated by the microcomputer 80 is written and stored in the electronic file.

  The battery 21 supplies power to the microcomputer 80 and the like when a power switch (not shown) provided in the coordinate detection device 3 is turned on.

  Here, the configuration of each of the coil sheets 100L and 100R will be described in detail. Each of the coil sheets 100L and 100R is a resin sheet formed in a thin rectangular shape as a whole. As described above, a plurality of sense coils are provided on the surfaces of the coil sheets 100L and 100R as shown in FIG. The sense coil is roughly classified into two types, that is, an X sense coil and a Y sense coil, depending on the arrangement direction. In FIG. 3, only the X sense coils Xk1 to Xk3 and Xs1 to Xs4 are shown and the Y sense coil is not shown in order to avoid the complexity of the illustration. These sense coils are formed of, for example, a copper wire having an insulating coating layer formed on the surface thereof. Although FIG. 3 shows an example of the coil sheet 100L, the coil coil 100R (not shown) is also provided with sense coils in the same arrangement configuration.

  Each of the X sense coils Xk1 to Xk3, Xs1 to Xs4 is formed in a substantially rectangular shape that is long in the Y-axis direction (vertical direction in the drawing). These X sense coils Xk1 to Xk3, Xs1 to Xs4 receive the magnetic field transmitted from the electronic pen 2 and detect the position of the electronic pen 2 mainly in the X-axis direction. Although not shown, the Y sense coil is formed in a substantially rectangular shape that is long in the X-axis direction, and mainly detects the position of the electronic pen 2 in the Y-axis direction.

  The X sense coils Xk1 to Xk3, Xs1 to Xs4 are provided with n odd numbers of 3 or more. These n X sense coils are arranged along the X-axis direction, and the whole constitutes the X detection coil unit 101. That is, in the above description using FIG. 3, the case where n = 7 is described as an example. The n X sense coils Xk1 to Xk3 and Xs1 to Xs4 are roughly classified into two types, that is, the X main detection coils Xk1 to Xk3 and the X auxiliary detection coils Xs1 to Xs4, depending on the arrangement and functions. The X main detection coils Xk1 to Xk3 are arranged in even numbers in the order of the X-axis direction, and the X auxiliary detection coils Xs1 to Xs4 are arranged in odd numbers. In the illustrated example, the X detection coil unit 101 includes three X main detection coils Xk1 to Xk3 and four X auxiliary detection coils Xs1 to Xs4 arranged in parallel in the X axis direction. That is, the X auxiliary detection coil Xs1, the X main detection coil Xk1, the X auxiliary detection coil Xs2, the X main detection coil Xk2, the X auxiliary detection coil Xs3, the X main detection coil Xk3, and the X auxiliary detection coil Xs4 are summed alternately. Seven are provided.

  The width direction dimension along the X-axis direction of the X auxiliary detection coils Xs1 to Xs4 is set to be narrower than that of the X main detection coils Xk1 to Xk3. The X main detection coils Xk1 to Xk3 and the X auxiliary detection coils Xs1 to Xs4 are formed in the same size and the same shape, respectively. Particularly in this example, the width direction dimension Ws of each X auxiliary detection coil Xs1 to Xs4 is set to half of the width dimension Wk of each X main detection coil Xk1 to Xk3. Adjacent X main detection coils Xk1 to Xk3 are arranged so as to be overlapped in the X-axis direction at a pitch interval Pk that is half of their widthwise dimension Wk. In FIG. 3, the Y-axis direction positions of the adjacent X main detection coils Xk1 to Xk3 and the X auxiliary detection coils Xs1 to Xs4 are the same. However, in FIG. 3, the X main detection coils Xk1 to Xk3 and the X auxiliary detection coils Xs1 to Xs4 are shown as being slightly shifted from each other as appropriate in order to avoid the complexity of the illustration and make it easy to see (the same applies to the following drawings). Furthermore, the longitudinal dimensions of the X auxiliary detection coils Xs1 to Xs4 and the X main detection coils Xk1 to Xk3 along the Y-axis direction are substantially the same. However, in FIG. 3, the longitudinal dimensions of the X auxiliary detection coils Xs <b> 1 to Xs <b> 4 are appropriately longer than the X main detection coils Xk <b> 1 to Xk <b> 3 in order to avoid the complexity of the illustration and make it easy to see (the following figures). The same applies to the above). Further, in FIG. 3, only the leftmost one is indicated by a thick solid line and the other X sense coils are indicated by broken lines so that the shapes of the two types of X sense coils can be easily distinguished from each other (the following figures). The same applies to the above).

  The center positions Cs2 and Cs3 in the width direction of the two center X auxiliary detection coils Xs2 and Xs3 are arranged at intermediate positions between the width direction center positions Ck1, Ck2 and Ck3 of the X main detection coils Xk1 to Xk3. . The center positions Cs1 and Cs4 in the width direction of the two outer X auxiliary detection coils Xs1 and Xs4 are outside the width center positions Ck1 and Ck3 of the two outer X main detection coils Xk1 and Xk3, respectively. They are spaced apart by a distance half the pitch interval Pk of Xk1 to Xk3. As described above, the X auxiliary detection coils Xs1 to Xs4 are arranged at the pitch interval Ps having the same distance as the pitch interval Pk of the X main detection coils Xk1 to Xk3.

  Further, in the following, a method for detecting the X coordinate position of the electronic pen 2 using the X detection coil unit 101 having the above-described arrangement configuration will be described. The detection method can be applied.

<Change characteristics of detection voltage>
First, the change characteristic of the detection voltage in each sense coil will be described. As described above, when the electronic pen 2 is moved along the width direction with respect to the sense coils La and Lb formed in a substantially rectangular shape as a whole, the detection as the signal S1 as shown in FIG. The voltage e changes. The detection voltage e becomes maximum at the center position in the width direction of the sense coils La and Lb, and decreases rapidly as the distance from the center position increases. When the electronic pen 2 is positioned slightly outside the wiring of the sense coils La and Lb, magnetic induction does not act and the detection voltage e is locally zero. This point is the null point N. A relatively weak detection voltage e is generated outside the null point N, and gradually increases as the distance from the sense coils La and Lb increases. Further, as can be seen by comparing FIG. 4A and FIG. 4B, when the width dimension of the sense coil Lb is reduced, the maximum voltage e at the center position is also reduced and the change in the detection voltage is shown. The overall width of the curve is also reduced.

  Although not particularly shown, when the electronic pen 2 is moved along the longitudinal direction (vertical direction in the figure) inside the sense coils La and Lb, the detection voltage corresponding to the position in the width direction at that time. Only e will be maintained. Coordinate data is calculated using the detection voltage thus obtained. Hereinafter, the details will be sequentially described.

<Comparative example>
First, in order to explain the premise of this embodiment, as a comparative example, as shown in FIG. 5, five X sense coils Xc1, Xc2, Xc3, Xc4, and Xc5 having the same widthwise dimension Wc are The case of the X detection coil unit 101c arranged in the X axis direction with a constant pitch interval Pc will be described. In FIG. 5, the output value is on one axis, in this example the vertical axis. The position information, that is, the X coordinate position is set on the other axis, in this example, the horizontal axis. Further, the characteristic curves Tc1, Tc2, Tc3, Tc4, and Tc5 in FIG. 5 correspond to the five X sense coils Xc1, Xc2, Xc3, Xc4, and Xc5, respectively. It represents the correlation characteristics.

  First, as a premise, in order to calculate the coordinate data with sufficiently high accuracy, it is necessary to use detection voltages of at least three consecutive sense coils. Therefore, in the case of the arrangement configuration of the X sense coils Xc1 to Xc5 shown in FIG. 5, first, of the two second and fourth X sense coils Xc2 and Xc4, the one with the highest detection voltage is the peak coil. Identified. After that, the coordinate data in the X-axis direction is obtained by using the detected voltages of the three X-sense coils, which are a combination of the identified one peak coil and two X-sense coils adjacent to both sides in the X-axis direction. Calculated.

  As an example, a case where the electronic pen 2 is at a position Xs separated by a separation distance Ds in the direction from the center position Cc2 in the width direction of the X sense coil Xc2 toward the X-axis origin as shown in the drawing will be described as an example. . In this case, among the two X sense coils Xc2 and Xc4 to be specified, the X sense coil Xc2 whose center position in the width direction is closest to the position Xs is specified as the peak coil. The voltage detected by the peak coil Xc2 is the peak voltage value Ep. Of the voltages detected by the two X sense coils Xc1 and Xc3 located on both sides of the peak coil Xc2, the larger one is the peak auxiliary voltage value E1, and the smaller one is the peak auxiliary voltage value E2.

  The peak voltage value Ep corresponds to the peak output value described in each claim, and the peak auxiliary voltage values E1 and E2 correspond to the peak auxiliary output value. Moreover, the identification result of the peak coil and the peak auxiliary coil, and the detection result of the peak output value and the peak auxiliary output value correspond to the reception result of the writing signal described in each claim.

  Next, in the example of the present embodiment, the reference value Rs is obtained by the calculation formula 1000 × (Ep−E1) / (Ep−E2). Note that the coefficient of 1000 in this calculation formula is simply a value of magnification, and other numerical values may be appropriately applied. Next, the reference value Rs is converted into the separation distance Ds using the position coordinate table (details will be described later). As a result, the X coordinate position separated by the separation distance Ds from the center position Cc2 in the width direction of the peak coil Xc2 toward the X sense coil Xc1 that has detected the peak auxiliary voltage value E1 is determined as the position of the electronic pen 2 at that time. Is done.

<Position coordinate table>
Here, the position coordinate table will be described. This position coordinate table (not shown in particular) is correlation information that stores correlation characteristics between the distance D from the center position in the width direction of the peak coil and the reference value R. In other words, in the coordinate system shown in FIG. 5 with the detected voltage value on the vertical axis and the X coordinate position on the horizontal axis, the characteristic curve Tc2 representing the correlation characteristic between the peak voltage value Ep and the X coordinate position, and the peak The characteristic curves Tc1 and Tc3 representing the correlation characteristics between the two peak auxiliary voltage values E1 and E2 on both sides of the voltage value Ep and the X coordinate position are obtained by using the above calculation formulas, so that the coordinates of the separation distance D and the reference value R are obtained. It can be synthesized as one synthesis curve Gc in the system. The data content of the position coordinate table is a set of coordinate data of each line element point constituting the composite curve Gc.

  The data contents of the position coordinate table are affected by various parameters such as the arrangement configuration of the X sense coils Xc1 to Xc5 in the X detection coil unit 101c and the frequency of the alternating magnetic field lines output from the electronic pen 2. The data content of the position coordinate table is calculated by, for example, an actual measurement result made in the handwriting input device 1 whose specific specification configuration is known in advance, or a simulation result considering the characteristic curve of each X sense coil, As described above, it is stored in the ROM 80b. When calculating the coordinate position data of the electronic pen 2, the above-described position coordinate table is used for the reference value R calculated using the peak voltage value Ep and the measured values of the two peak auxiliary voltage values E1 and E2 on both sides thereof. By applying, it can be converted into the separation distance D.

<Diverging reference values>
Here, for example, when the second X sense coil Xc2 is a peak coil, the characteristic curves Tc1 and Tc3 of the two X sense coils Xc1 and Xc3 on both sides are in the width direction of the peak coil Xc2. It intersects on the center position Cc2. That is, the peak auxiliary voltage values of the X sense coils Xc1 and Xc3 on both sides are the same value E1 = E2. As a result, the value of the fraction (Ep−E1) / (Ep−E2) in the above calculation formula is 1 on the width direction center position Cc2, and the reference value R is the maximum value. As illustrated, the reference value R decreases as the distance from the center position Cc2 in the width direction increases. Since the change in the reference value R has the same behavior in both the increasing direction and the decreasing direction of the X direction coordinate value, the composite curve Gc indicating the change in the reference value R has a mirror image relationship centered on the center position Cc2 in the width direction. Become. The composite curve Gc also changes in the same mirror image relation with respect to the center position CC4 in the width direction of the fourth X sense coil Xc4, which is a specific target of other peak coils.

  However, this composite curve Gc shows the characteristic curve Tc2 and the peak auxiliary voltage value E2 of the peak coil Xc2 in the vicinity of the X coordinate position where Ep = E2 where Ep = E2 has continued to increase the separation distance Ds in the figure. Near the point Pa where the characteristic curve Tc3 of the detected X sense coil Xc3 intersects, in the vicinity of the X-axis direction position Xa, the denominator of the fraction (Ep−E1) / (Ep−E2) in the above formula is 0. Approaching the reference value Rs diverges. Specifically, as shown in the figure, the light diverges to −∞ as the distance Xs approaches the position Xa. Although not particularly illustrated, the light diverges to + ∞ as the distance Xs approaches the position Xa. In addition, on the position Xa itself between them, the sign of the reference value R is reversed, and the denominator of the fraction (Ep−E1) / (Ep−E2) in the above formula is 0, so the reference value The value of R becomes inconstant.

  As described above, the contents of the position coordinate table, which is correlation information, are a set of combinations of the separation distance D and the reference value R, which are the coordinate data of each line element constituting the composite curve Gc. In order to reliably convert the separation distance D from the reference value R calculated from the actually measured voltage value using this position coordinate table, the correspondence between the separation distance D and the reference value R in the position coordinate table is unique. That is, it must correspond one-on-one. However, if the content of the reference value R stored in the position coordinate table includes even an indefinite number corresponding to the position Xa described above, the uniqueness with the separation distance D is lost and appropriate conversion cannot be performed. That is, the position of the electronic pen 2 cannot be determined appropriately within the range of the separation distance Ds exceeding the position Xa.

  On the other hand, it is also conceivable to set the range portion A outside the position Xa in the X detection coil unit 101c as an invalid area where the position of the electronic pen 2 is not detected. However, as shown in the drawing, the area occupied by the invalid region A is relatively large as viewed in the entire area of the X detection coil unit 101c, and a large waste is generated in the entire X detection coil unit 101c. Also, changing the calculation algorithm only for the invalid area A causes the processing to be complicated, and should be avoided as much as possible.

  In order to eliminate such an ineffective region, the simplest method for removing the intersection Pa from the arrangement range of the X detection coil unit 101c is to narrow the pitch interval Pc of all the X sense coils Xc1 to Xc5. However, in this case, if the effective area of the X detection coil unit 101c is to be obtained equally, the required number of X sense coils is increased. Therefore, the power consumption increases by that amount, and the signal connection lines of each sense coil also increase, thereby increasing the area of the entire coil sheet.

<Method of this embodiment>
Therefore, in the present embodiment, as shown in FIG. 3, the width direction dimension Ws of the X sense coils Xs1 to Xs4 positioned in the odd-numbered order in the X-axis direction is set to the width of the even-numbered X sense coils Xk1 to Xk3. The above is solved by setting it appropriately shorter than the width direction dimension Wk. That is, as shown in FIG. 6, characteristic curves Tk1 to Tk3 and Ts1 to Ts4 of the detection voltages of the X sense coils Xk1 to Xk3, Xs1 to Xs4 can be arranged. As a result, for example, the characteristic curve Tk1 when the leftmost X main detection coil Xk1 in the figure becomes a peak coil, and the X auxiliary detection coil Xs2 that detects the lower peak auxiliary voltage value E2 of both sides of the characteristic curve Tk1. The X-axis direction position Xb of the intersection Pb with the characteristic curve Ts2 is out of the arrangement range of the X detection coil unit 101.

  As a result, in the range from the center position Ck1 in the width direction of the peak coil Xk1 to the end in the X-axis direction (the left end in the figure), the composite curve G does not take an indefinite reference value R. Uniqueness can be ensured in the entire range. In other words, by using a position coordinate table reflecting such a composite curve G, that is, a data group corresponding to the composite curve described in each claim, if one reference value R is calculated, one separation distance D is surely obtained. And the position of the electronic pen 2 can be determined based on this. Thus, since the position of the electronic pen 2 can be determined in the entire arrangement range of the X auxiliary detection coils Xs1 and Xs4 located on the outermost side, it is not necessary to set an invalid area.

  In the present embodiment, not only the two X auxiliary detection coils Xs1 and Xs4 located at both ends in the X-axis direction of the X detection coil unit 101, but also all the X auxiliary detection coils Xs1, Xs2, which are located at odd numbers. Xs3 and Xs4 similarly set the width direction dimension Ws to be narrow. Then, the first peak coil is identified by only one of the X main detection coils Xk1 to Xk3 having a wide width direction dimension Wk positioned evenly. As a result, the combination of the three X sense coils including the specified peak coil and the X auxiliary detection coils on both sides of the specified peak coil is always arranged in the order of narrow, wide, and narrow at regular pitch intervals along the X-axis direction. Are selected in the same pattern. As a result, the position coordinate table reflecting the composite curve G is the entire range from the center position in the width direction of the X main detection coil, which is the center position of this pattern, to the end in the X axis direction of the X auxiliary detection coil on one side. The same position coordinate table can be applied even in the range up to the other end.

  Further, regardless of which X main detection coil Xk1 to Xk3 is specified as the peak coil, the width direction dimension patterns of the three X sense coils selected based on the peak coil are all the same, narrow, wide, and narrow. As a result, the same position coordinate table can be applied by symmetrically distributing in the X-axis direction from the center position in the width direction of the peak coil. That is, the position of the electronic pen 2 can be calculated with the same calculation algorithm using a common position coordinate table over the entire arrangement range of the X detection coil unit 101.

  Note that the number of data stored in the position coordinate table, that is, the number of combinations of the separation distance D and the reference value R, is in the range from the center position Ck1 in the width direction of the peak coil Xk1 to the end in the X-axis direction shown in FIG. It is only necessary to memorize the corresponding amount. Two X-axis direction positions Cs2 and Cs3 shown in FIG. 6 respectively coincide with intermediate positions between two adjacent X main detection coils. Therefore, the X main detection coil specified as the peak coil is switched depending on which side the electronic pen 2 is located with respect to the X-axis direction positions Cs2 and Cs3. As a result, the range of the position Ck1 to the position Cs2, the range of the position Ck2 to the position Cs2, the range of the position Ck2 to the position Cs3, and the range of the position Ck3 to the position Cs3, respectively, Among them, only a part of the one having the smaller separation distance D is used. As a result, the common position coordinate table and calculation algorithm can be used in the entire arrangement range of the X detection coil unit 101.

  Further, as described above, since the X-axis direction position Xb where the reference value R becomes an indefinite number is out of the arrangement range of the X detection coil unit 101, the lower limit value of the reference value R stored in the position coordinate table is The absolute value always converges within the specified value without diverging to -∞.

  The contents of the control processing performed by the CPU 80a of the coordinate detection device 3 in order to realize the position detection function as described above will be described in order with reference to FIG. FIG. 7 shows only a procedure related to position detection in the X-axis direction, and although not particularly shown, the same procedure may be executed in the Y-axis direction.

  In FIG. 7, this process is started when the user turns on the power of the coordinate detection device 3. First, in step SS5, the CPU 80a sequentially transmits a selection signal S3 to the MUX 62, receives the magnetic field generated from the electronic pen 2 by all the even-numbered X main detection coils Xk1 to Xk3, and detects the voltage.

  Then, the process proceeds to Step SS10, and the CPU 80a determines whether or not a voltage equal to or higher than a predetermined threshold is detected from at least one of the X main detection coils Xk1 to Xk3 in Step SS5. If no voltage exceeding the predetermined threshold is detected from any of the X main detection coils Xk1 to Xk3, the determination is not satisfied, and the same procedure is repeated by returning to step SS5. On the other hand, if any one of the voltages equal to or higher than the predetermined threshold is detected, the determination is satisfied, and the routine goes to Step SS15.

  In Step SS15, the CPU 80a specifies the X main detection coil that has detected the highest voltage among the voltages detected in Step SS5 as a peak coil, and sets the maximum voltage as the peak voltage value Ep.

  Thereafter, the process proceeds to step SS20, and the CPU 80a sequentially transmits a selection signal S3 to the MUX 62, and is generated from the electronic pen 2 by two X auxiliary detection coils adjacent to both sides of the peak coil specified in step SS15 in the X-axis direction. A magnetic field is received and a voltage is detected.

  Then, the process proceeds to Step SS25, and the CPU 80a sets the larger one of the voltages detected in Step SS20 as the peak auxiliary voltage value E1, and the smaller one as the peak auxiliary voltage value E2.

  Thereafter, the process proceeds to step SS30, and the CPU 80a calculates the reference value R from the calculation formula (Ep-E1) / (Ep-E2).

  Then, the process proceeds to step SS35, and the CPU 80a converts the reference value R calculated in step SS30 to a separation distance D using the position coordinate table described above.

  Thereafter, the process proceeds to Step SS40, and the CPU 80a moves the position separated by the separation distance D converted in Step SS35 from the center position in the width direction of the peak coil toward the X auxiliary detection coil that detects the peak auxiliary voltage value E1. The X coordinate position of the electronic pen 2 is determined. Then, the CPU 80 a stores the determined X coordinate position in the flash memory 72.

  Then, the process proceeds to step SS45, and the CPU 80a determines whether or not an operation for instructing to end this flow is input via an appropriate operation unit. If the end operation has not been input, the determination is not satisfied and the process returns to step SS5 and the same procedure is repeated. If an end operation has been input, the determination is satisfied and this flow ends.

  In the above, step SS5 in the flow of FIG. 7 functions as the primary output acquisition means described in each claim, and step SS15 functions as the peak coil specifying means. Step SS20 functions as a peak auxiliary coil specifying unit and also functions as a secondary output acquisition unit.

  Further, step SS30 functions as a reference value calculation unit, step SS35 functions as a separation distance conversion unit, step SS40 functions as a position information determination unit, and these three steps function as a calculation unit.

  As described above, in the handwriting input device 1 of the present embodiment, the even-numbered X main detection coils Xk1 to Xk3 and the odd-numbered X auxiliary detection coils Xs1 to Xs4 are alternately arranged along the X-axis direction. Then, position information of the electronic pen 2 is calculated. At this time, the width direction dimension Ws of the X auxiliary detection coils Xs1 to Xs4 in the X axis direction is smaller than the width direction dimension Wk of the X main detection coils Xk1 to Xk3. By reducing the width direction dimension Ws of the X auxiliary detection coils Xs1 and Xs4 arranged at both ends of the X-axis direction arrangement, the undetectable range at both ends of the X detection coil unit 101 is reduced, and high accuracy is achieved over a wide range. Position detection can be performed. Further, not only the X auxiliary detection coils Xs1 and Xs4 arranged at both ends of the X-axis direction array, but also the X auxiliary detection coils Xs2 and Xs3 positioned at the intermediate part of the other arrays are arranged at both ends. Similarly to Xs1 and Xs4, the width direction dimension Ws is reduced. In other words, by sharing the width direction dimension Ws in the X-axis direction of all the X auxiliary detection coils Xs1 to Xs4, the position coordinate table corresponding to the combined curve G stored in the ROM 80b is stored in all the X auxiliary detection coils Xs1 to Xs1. A common mode can be used for Xs4.

  Here, in the present embodiment, the reference value R in the position coordinate table corresponding to the composite curve G does not diverge, that is, an indefinite reference value R is associated with one separation distance D. The seven X sense coils Xk1 to Xk3 and Xs1 to Xs4 of the X detection coil unit 101 are arranged so as to prevent a crossing point Pa from occurring. Alternatively, even if an intersection Pb occurs, the seven X sense coils Xk1 to Xk3, Xs1 to Xs4 are arranged so that the intersection Pb is outside the range where the seven X sense coils Xk1 to Xk3, Xs1 to Xs4 are arranged. Is arranged. In other words, even if there is no intersection Pa in which an indefinite reference value R is associated with one separation distance D, and there is an intersection Pb, the intersection Pb has seven X senses. A data group corresponding to the composite curve Gc that falls outside the range in which the coils Xk1 to Xk3 and Xs1 to Xs4 are arranged is returned as a position coordinate table. In other words, specifically, the X detection coil unit 101 has Ep> E2 on the composite curve G applied within the coil position range where the seven X sense coils Xk1 to Xk3, Xs1 to Xs4 are arranged. The seven X sense coils Xk1 to Xk3 and Xs1 to Xs4 are arranged so as to be. Thus, when the calculation is performed using the composite curve G in steps SS30 to SS40 in the flow of FIG. 7, the peak voltage value Ep from the one peak coil and the peak auxiliary voltage value E1 from the two peak auxiliary coils are calculated. , E2, the corresponding separation distance D can always be determined uniquely. In addition, at that time, it is not necessary to use separate algorithms for both ends of the array and the others, and the calculation can be performed using only one common algorithm. As a result, it is possible to simplify and speed up the processing in the calculation.

  As a result, in the present embodiment, highly accurate position detection can be performed over a wide range of the X detection coil unit 101, and calculation processing can be simplified and speeded up. In addition, as described above, in this embodiment, the sense coil is divided into the X main detection coils Xk1 to Xk3 and the X auxiliary detection coils Xs1 to Xs4, and the auxiliary coil used for position detection is specified as a peak coil. The X main detection coil is limited to two coils on both sides. Thereby, compared with the case where a main detection coil and an auxiliary | assistant detection coil are not divided as mentioned above, there also exists an effect which can reduce the number of coils to scan.

  In the above embodiment, as shown in FIGS. 3 and 6, an example in which seven X sense coils Xk1 to Xk3 and Xs1 to Xs4 are arranged in the X detection coil unit 101 is shown, but the present invention is not limited thereto. As described above, an odd number of X sense coils may be arranged in the X detection coil unit 101. Therefore, although not particularly illustrated, for example, a total of three X sense coils are arranged, and one of them is set as an X main detection coil, and two at both sides thereof are set as X auxiliary detection coils and are wider than the X main detection coil. It is good also as a structure which set the direction dimension short. In this case, only one X main detection coil is necessarily the peak coil.

  Moreover, in the said embodiment, although the synthetic | combination curve G which is correlation information was memorize | stored as a data group of a position coordinate table, it is not restricted to this. For example, the composite curve G may be stored and used as an approximate polynomial.

  Further, in the present embodiment, in particular, the X detection coil unit 101 converges the reference value R in the position coordinate table corresponding to the composite curve G so that the separation distance D is in the vicinity of both ends of the coil position range below a predetermined value. As described above, seven X sense coils Xk1 to Xk3 and Xs1 to Xs4 are arranged. Thereby, as described above, the divergence of the reference value R of the position coordinate table corresponding to the composite curve G is prevented, and the peak voltage value Ep from one peak coil and the peak auxiliary voltage value from two peak auxiliary coils are prevented. For E1 and E2, the corresponding separation distance D can always be determined uniquely.

  In this embodiment, in particular, the width direction dimensions Wk in the X axis direction of the X main detection coils Xk1 to Xk3 are all the same, and the width direction dimensions Ws in the X axis direction of the X auxiliary detection coils Xs1 to Xs4 are all the same. The same. Thus, by sharing the width direction dimensions Wk and Ws in the X-axis direction between all the X main detection coils Xk1 to Xk3 and between all the X auxiliary detection coils Xs1 to Xs4, the electronic pen 2 side Even if the voltage value from the X detection coil unit 101 fluctuates for some reason, such as output change or change in the environment around the device, the influence of the fluctuation is affected by all X main detection coils Xk1 to Xk3, X auxiliary detection coils. It occurs equally in Xs1 to Xs4. As a result, as in the case of an arrangement configuration in which only the X sense coils at both ends are made small, the influence of the above-described variation differs between the both ends and the intermediate portion, and the overall detection accuracy does not decrease. Since the calculation can be performed using only one common algorithm, the processing in the calculation of the position information of the electronic pen 2 can be simplified and speeded up.

  In the present embodiment, in particular, the calculation means for calculating the position of the electronic pen 2 uses the peak voltage value Ep actually detected and the two peak auxiliary voltage values E1 and E2 to calculate the reference value R from the above formula. The larger peak auxiliary voltage value E1 is detected from the procedure of step SS30 to be calculated, the procedure of step SS35 for converting the reference value R into the separation distance D based on the position coordinate table, and the center position in the width direction of the peak coil. The procedure of step SS40 for determining the position separated by the separation distance D toward the peak auxiliary coil as the position of the electronic pen 2 is executed. Thus, if the actual measurement values of the peak voltage value Ep and the two peak auxiliary voltage values E1 and E2 can be detected, the reference value R calculated based on them can be converted into the separation distance S using the position coordinate table, and the electronic pen 2 Can be calculated easily and with high accuracy.

  In the above embodiment, the width direction dimension Ws of the X auxiliary detection coils Xs1 to Xs4 arranged at odd numbers in the X detection coil unit 101 is set to the width direction of the X main detection coils Xk1 to Xk3 arranged at even numbers. By setting it to be narrower than the dimension Wk, it was possible to eliminate invalid areas at both ends in the X-axis direction. However, even if the width direction dimension Ws of the X auxiliary detection coils Xs1 to Xs4 is too narrow, the detection performance of the X detection coil unit 101 is deteriorated. Therefore, in the following, the influence of the ratio of the width direction dimension between the X main detection coils Xk1 to Xk3 and the X auxiliary detection coils Xs1 to Xs4 on the detection performance of the X detection coil unit 101 will be verified.

<When the width direction dimension of the X auxiliary detection coil is too small>
For example, in the X detection coil unit 101 shown in FIGS. 3 and 6 of the above embodiment, the arrangement relationship between the X sense coils Xk1 to Xk3 and Xs1 to Xs4 is left as it is, and the width direction of the X auxiliary detection coils Xs1 to Xs4 is maintained. The case where only the dimension Ws is set to a half is verified. In other words, the ratio Ws / Wk of the width direction dimension of the X auxiliary detection coils Xk1 to Xk3 to the X main detection coils Xk1 to Xk3 is set to 1/4. In this case, the characteristic curves Tk1 to Tk3 and Tu1 to Tu4 of the X sense coils Xk1 to Xk3, Xu1 to Xu4 and the combined curve Gu have the relationship shown in FIG.

  In FIG. 8, the change of the composite curve Gu in the vicinity of the width direction center positions Ck1 to Ck3 of the X main detection coils Xk1 to Xk3 is different from the case of the above embodiment, and is a parabola having a maximum value as shown in part B. Draw a shape and intersect. That is, the sensitivity of the composite curve Gu is lowered. This is because the width-direction dimensions of the corresponding characteristic curves Tu1 to Tu4, along with the X auxiliary detection coils Xu1 to Xu4, are too small. At that time, as shown in part C, the characteristic curves Tu1 to Tu4 of the two adjacent X auxiliary detection coils Xu1 to Xu4 intersect each other in the vicinity of the null point where the peak auxiliary voltage values E1 and E2 are low. In this case, the content of the position coordinate table corresponding to the composite curve Gu loses the uniqueness of the reference value R with respect to the separation distance D, and the position information of the electronic pen 2 cannot be calculated reliably. That is, an invalid region is generated in the vicinity of the center positions Ck1 to Ck3 in the width direction of the X main detection coils Xk1 to Xk3.

  In the above embodiment, as described above, the X auxiliary detection coils for the X main detection coils Xk1 to Xk3 so that the intersections Pa and Pb that make the reference value R unconstant are removed from the X-axis direction end of the X detection coil unit 101. The ratio of the width direction dimensions of Xs1 to Xs4 was set to 1/2 smaller than 1. On the other hand, in order to maintain the sensitivity of the combined curve G in the vicinity of the center positions Ck1 to Ck3 in the width direction of the X main detection coils Xk1 to Xk3, the X auxiliary detection coils Xu1 to Xx for the X main detection coils Xk1 to Xk3. It is necessary to set the ratio of the dimension in the width direction of Xu4 to be higher than a predetermined value.

<Relationship between width ratio between coils and invalid area width>
As a result of various experiments and simulations, the inventors of the present application have newly found a relationship as shown in FIG. In FIG. 9, the horizontal axis represents the ratio of the dimension in the width direction of the X auxiliary detection coil to the X main detection coil. Further, the invalid area width generated at both ends of the X detection coil unit 101 and the invalid area width generated at the center position in the width direction of each X main detection coil (abbreviated as “central part” in the drawing) are shown on the vertical axis. ing. Each parameter condition is that the frequency of the magnetic field output from the electronic pen 2 is 250 kHz, the width direction dimension of the X main detection coil is 20 mm, and the pitch interval between the X sense coils is 7 mm.

  As shown in FIG. 9, the width of the invalid region generated at both ends of the X detection coil unit 101, that is, the size at which the intersection Pa enters both ends of the X detection coil unit 101 is such that the width-direction dimension ratio is 1/2 or less. It can be seen that if there is, it can be suppressed to almost zero. In addition, the invalid region width generated at the center position in the width direction of each X main detection coil, that is, the separation distance of the maximum value on the combined curve, can be suppressed to almost zero if the width direction dimension ratio is 1/3 or more. I understand. As can be seen from FIG. 10 corresponding to FIG. 6, when the width direction dimension ratio Wv / Wk is 1/3, both ends of the X detection coil unit 101v and each X main detection are detected. The invalid area width does not occur in each of the width direction center positions Ck1 to Ck3 of the coils Xk1 to Xk3.

  Thereby, in the said embodiment, it is desirable for the width direction dimension of the X-axis direction of the X auxiliary detection coil to be not less than 1/3 and not more than 1/2 of the width direction dimension of the X main detection coil in the X-axis direction. As a result, the undetectable range at both ends of the X detection coil unit 101 can be reliably reduced, and highly accurate position detection can be performed over a wide range.

<Optimum value of the ratio of dimensions in the width direction between coils>
Next, the optimum value of the ratio of the dimension in the width direction between the coils on the assumption that there is no invalid area in the X detection coil unit 101 will be verified with reference to FIG. If the pitch interval between the X sense coils is unchanged, and only the width direction dimension of the X auxiliary detection coil is changed, the size of the effective region of the X detection coil unit 101 changes. For example, two configuration examples when one X main detection coil Xk (broken line portion in the figure) is arranged in the center and two X auxiliary detection coils Xs1, Xs2 (solid line parts in the drawing) are arranged on both sides thereof. Is shown in FIG. In the arrangement configuration of FIG. 11A and the arrangement configuration of FIG. 11B, the pitch interval between the X sense coils Xk, Xs1, and Xs2 and the width direction dimension of the central X main detection coil Xk are the same. However, the width direction dimensions of the X auxiliary detection coils Xs1, Xs2 on both sides are different.

  The effective area in the X-axis direction of the X detection coil unit 101 is the common width between the center positions in the width direction of the two X auxiliary detection coils Xs1 and Xs2, and the width direction dimensions of the two X auxiliary detection coils Xs1 and Xs2. Equal to the sum of half the width of Ws. As long as the pitch interval between the X sense coils Xk, Xs1, and Xs2 is not changed, the length of the common width is constant regardless of the change in the width dimension Ws of the X auxiliary detection coils Xs1, Xs2. Therefore, as long as the invalid area is not generated at both ends in the X-axis direction of the X detection coil unit 101, the effective area of the X detection coil unit 101 can be increased as the width direction dimension Ws of the X auxiliary detection coils Xs1 and Xs2 increases. Is preferred. In other words, the ratio of the dimension in the width direction of the X auxiliary detection coil to the X main detection coil is 1/2, which is the upper limit value that does not generate an invalid region at both ends in the X axis direction of the X detection coil unit 101 as described above. It is.

  In the above, the electronic pen 2 includes the battery 43 as a self-power source, the magnetic field generated by the LC oscillation circuit 41 by the electromotive force of the battery 43 is received by the sense coil, and the contact between the electronic pen 2 and the notebook 30 is received. Although the point coordinate data was calculated, the present invention is not limited to this. That is, the self-power supply is not provided on the electronic pen side, the electromotive force is induced in the resonance circuit of the electronic pen by magnetic induction from the coil on the device side, and the electric charge is accumulated in the capacitor of the electronic pen, and the accumulated charge is used. You may apply this invention to the structure which receives the magnetic field which the electronic pen generate | occur | produced with the coil by the side of an apparatus, and acquires the position coordinate of the contact point of an electronic pen and the notebook 30. FIG. In this case, the same effect is obtained.

  In the above, the arrows shown in each drawing such as FIG. 2 indicate an example of the signal flow, and the signal flow direction is not limited. Further, the flowchart shown in FIG. 7 or the like does not limit the present invention to the procedure shown in the above flow, and the procedure is added / deleted or the order is changed without departing from the spirit and technical idea of the invention. Also good.

  In addition to those already described above, the methods according to the above-described embodiments and modifications may be used in appropriate combination.

  In addition, although not illustrated one by one, the present invention is implemented with various modifications within a range not departing from the gist thereof.

1 Handwriting input device (electronic writing device)
2 Electronic pen (electronic writing instrument)
3 Coordinate detection device 10 Sheet body 30 Notes 62 MUX
80a CPU
80b ROM (correlation storage means)
100L Left coil sheet 100R Right coil sheet 101 X detection coil section Wk X main detection coil width direction dimension Ws X auxiliary detection coil width direction dimension Xk1 to Xk3 X main detection coil Xs1 to Xs4 X auxiliary detection coil Pa, Pb Intersection

Claims (5)

From an electronic writing instrument that has a signal generating means including a coil for applying a magnetic field, and generates and transmits a writing signal for position detection for performing data input corresponding to the writing content to the writing object by the signal generating means Receiving the transmitted writing signal and outputting an output value induced by the writing signal, the coil including n coils (n is an odd number of 3 or more) arranged along a predetermined direction, At least one main detection coil for detecting a peak output value that is an even numbered array among n arrays along the predetermined direction and that serves as a reference for position detection, and n along the predetermined direction A plurality of auxiliary detection coils arranged in an odd number of the plurality of arrays and having a size in the predetermined direction smaller than that of the main detection coil, and a detection coil unit,
An arithmetic means for calculating position information of the electronic writing instrument based on a reception result in the detection coil unit including an output value of the writing signal;
Primary output acquisition means for acquiring an output value of the at least one main detection coil arranged in an even number;
Peak coil specifying means for specifying, as a peak coil, the main detection coil that has detected the peak output value that is the maximum output value among the at least one main detection coil whose output value has been acquired by the primary output acquisition means. When,
Peak auxiliary coil specifying means for specifying two auxiliary detection coils adjacent to both sides along the predetermined direction of the peak coil specified by the peak coil specifying means as peak auxiliary coils;
Secondary output acquisition means for acquiring output values of the two peak auxiliary coils specified by the peak auxiliary coil specifying means;
Have
The computing means is
Using the peak output value from the peak coil specified by the peak coil specifying means and the peak auxiliary output value from the two peak auxiliary coils specified by the peak auxiliary coil specifying means, the electron An electronic writing device that acquires the position information of a writing instrument,
The output value is set on one axis and the position information is set on the other axis, and a plurality of characteristics representing correlation characteristics between the position information and each of the peak output value of the peak coil and the peak auxiliary output value of the two peak auxiliary coils. One composite curve obtained by appropriately combining characteristic curves, or a data group corresponding to the composite curve, the separation distance in the predetermined direction from the center position of the peak coil to the position of the electronic writing instrument, Formula (Ep-E1) / (Ep-E2) when the electronic writing instrument is located at the separation distance
However,
Ep: Peak voltage value E1: Larger peak auxiliary output value E2: Correlation information including the one composite curve or the data group representing the correlation characteristic with the reference value calculated by the smaller peak auxiliary output value Stored correlation storage means,
In the detection coil unit, the n coils are arranged such that Ep> E2 on the composite curve applied within the coil position range where the n coils are arranged. Electronic writing device. The detection coil section is
Among the data group corresponding to the composite curve, the n coils are arranged so that the output value of the data group in which the position information is in the vicinity of both ends of the coil position range converges to a predetermined value or less. The electronic writing apparatus according to claim 1, wherein 3. The electronic writing apparatus according to claim 1, wherein a dimension of the auxiliary detection coil in the predetermined direction is 1/3 or more and 1/2 or less of a dimension of the main detection coil in the predetermined direction. . The dimension in the predetermined direction is a dimension in the width direction of the coil,
The dimension of the said width direction of the said main detection coil is all the same, respectively, The dimension of the said width direction of the said auxiliary | assistant detection coil is all the same, The any one of Claim 1 thru | or 3 characterized by the above-mentioned. Electronic writing device. The computing means is
Reference value calculation means for calculating the reference value from the calculation formula using the peak output value actually detected and the two peak auxiliary output values;
A separation distance conversion means for converting the reference value calculated by the reference value calculation means into the separation distance based on the correlation information;
A position for determining, as the position information of the electronic writing instrument, a position separated from the center of the peak coil by the separation distance converted by the separation distance conversion means toward the peak auxiliary coil that has detected the larger peak auxiliary output value. Information determination means;
The electronic writing apparatus according to claim 4, further comprising:

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