Electronic pen, handwriting input device and electronic pen core body

Abstract

To provide a handwriting input device which simplifies a configuration of an electronic pen, and which can be formed at low costs.SOLUTION: An electronic pen 2 is of an electromagnetic induction type that includes a resonance circuit which includes a coil 211 and a capacitor 215. A magnet portion and a yoke portion holding such a magnet portion are provided at the pen tip portion of a core body 213 that passes through a through-hole of a magnetic core 212 around which the coil 211 is wound. Moreover, a handwriting input device includes: the electronic pen 2; and a position detecting device unit 13 that has an electromagnetic induction type position detection sensor 12 placed so as to overlap with a magnetic sheet 11 that changes the color at a portion which comes close to or is in contact with the magnetic pole, under the magnetic sheet 11.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an electronic pen and a handwriting input device configured using the electronic pen. [Background technology]

[0002] Instead of handwriting input on paper using a writing instrument such as a ballpoint pen or pencil, it is becoming common, along with the demand for paperless systems, to use an electronic pen to input information into an input device such as a tablet terminal that has a position detection device unit equipped with a position detection sensor that detects the position indicated by the electronic pen, and then store the input handwritten information as electronic data.

[0003] In this case, it is necessary to make the handwritten information input by the electronic pen visible to the user. To this end, the tablet terminal is provided with a display panel superimposed on the position detection sensor and a display control circuit that controls the display panel to display a display image (such as a writing path) corresponding to the coordinate data of the position indicated by the electronic pen detected by the position detection device.

[0004] In this case, the display panel may be an LCD (Liquid Crystal Display) or an organic EL (Electroluminescence) display, or electronic paper such as an electrophoretic display panel as described in Patent Document 1 (JP 2007-206845 A) or Patent Document 2 (JP 2007-206846 A). However, such tablet terminals have the problem of being expensive because they require a display panel and a display control circuit to display handwritten information based on coordinate information of the position indicated by the electronic pen detected by a position detection device.

[0005] On the other hand, for example, Patent Document 3 (JP 2018-37033 A) proposes a handwriting input device that includes a board device configured to allow paper to be clipped onto a flat board that houses a position detection device unit equipped with a position detection sensor, and an electronic pen that has writing implement functions such as a ballpoint pen function and interacts with the position detection sensor through signals.

[0006] In this handwriting input device, when handwriting is input on paper using the writing implement function of the electronic pen, coordinate information of the handwritten input trajectory is detected by a position detection device unit via a position detection sensor, and the detected coordinate information is output to, for example, a personal computer or stored in an internal memory unit for use. With this handwriting input device, the handwritten input trajectory is drawn on paper using the writing implement function of the electronic pen, so there is no need for a display panel for displaying and confirming the handwritten information as described above, which reduces costs and is very convenient. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-206845 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-206846 [Patent Document 3] Japanese Patent Application Publication No. 2018-37033 Summary of the Invention [Problem to be solved by the invention]

[0008] However, the handwriting input device of Patent Document 3 requires the electronic pen to have the functionality of a writing implement, such as a ballpoint pen, which makes the electronic pen configuration complex and expensive. Furthermore, while this is convenient for storing paper on which handwritten input marks are formed, for applications that do not require paper storage, it is difficult to physically erase marks written on paper using a ballpoint pen or other function. This necessitates the need to replace the paper as needed, which is troublesome. Furthermore, even if the marks on the paper can be erased with an eraser, there is the problem of eraser residue.

[0009] SUMMARY OF THE INVENTION An object of the present invention is to provide an electronic pen and a handwriting input device that can solve the above problems. [Means for solving the problem]

[0010] In order to solve the above problems, A handwriting input device including a position detection device and an electronic pen, The position detection device a magnetic sheet that changes color at a position where a magnetic pole approaches or comes into contact with the magnetic sheet; an electromagnetic induction type position detection sensor disposed under and overlapping the magnetic sheet; Equipped with The electronic pen is A coil and a magnetic core around which the coil is wound and which has a through hole in the axial direction; a capacitor that forms a resonant circuit together with the coil; a rod-shaped core body to be inserted into the through hole of the magnetic core, the core body having a magnet portion at a pen tip portion of the core body and a yoke portion for holding the magnet portion; Equipped with the position detection sensor detects the pen position of the electronic pen through electromagnetic induction coupling with a sensor signal having a frequency corresponding to a resonant frequency of the resonant circuit; The detected pen position is displayed based on the fact that the magnet portion arranged at the pen tip portion of the electronic pen causes a color change at a position on the magnetic sheet near the pen tip. The present invention provides a handwriting input device characterized by the above features. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram showing the appearance of a tablet terminal constituting an embodiment of a handwriting input device according to the present invention; [Figure 2] 1 is a diagram showing an example of a configuration of a main part of an embodiment of a handwriting input device according to the present invention; [Figure 3] 1 is a diagram illustrating an example of a configuration of a main part of an embodiment of a handwriting input device according to the present invention; [Figure 4] 1 is a diagram illustrating an example of the configuration of a main part of an electronic pen that constitutes an embodiment of a handwriting input device according to the present invention; [Figure 5] 1A and 1B are diagrams for explaining a configuration example of a core body of an electronic pen constituting an embodiment of a handwriting input device according to the present invention; [Figure 6] 3A and 3B are diagrams for explaining a magnetic field generated by a magnetic circuit formed in a core body of an electronic pen constituting an embodiment of a handwriting input device according to the present invention. [Figure 7] 1 is a block diagram showing an example of the configuration of an electronic circuit of an embodiment of a handwriting input device according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0012] [Appearance and basic configuration of the embodiment of the handwriting input device] 1 is a diagram illustrating the appearance of an embodiment of a handwriting input device according to the present invention. In this embodiment, the handwriting input device is configured to include a tablet terminal 1 and an electronic pen 2.

[0013] <Example of tablet device 1 configuration> Tablet terminal 1 of this embodiment has a thin, rectangular plate-like configuration with a thickness of, for example, a few millimeters, and one flat surface of the plate-like body is used as a surface, with most of this surface used as a handwriting input area (instruction input area) for use with electronic pen 2. The surface of this handwriting input area is used as handwriting input surface (instruction input surface) 1A. Figure 1 is a view of handwriting input surface 1A of tablet terminal 1 seen from above, perpendicular to handwriting input surface 1A.

[0014] In this embodiment, an operation panel unit 1B is provided in an area above the handwriting input area on the surface of the tablet terminal 1. Operation buttons such as a power button 1Ba, a handwriting input end button 1Bb, and an information transmission button 1Bc, as well as display indicators such as a power indicator 1Bd and a communication indicator 1Be, are arranged on the operation panel unit 1B. The power indicator 1Bd and the communication indicator 1Be are configured, for example, with LEDs (Light Emitting Diodes).

[0015] Although not shown, the tablet terminal 1 of this embodiment is equipped with a rechargeable battery, and when the power button 1Ba is turned on, the battery supplies drive voltage to necessary circuit components. The handwriting input end button 1Bb is pressed by the user when saving handwritten input data for each page in a storage unit, as will be described later. The tablet terminal 1 of this embodiment is also equipped with a wireless communication unit, and when the information transmission button 1Bc is pressed, the stored handwritten input data for each page is sent to a server device comprising an external computer.

[0016] The power indicator 1Bd is for notifying that the power is on, and the communication indicator 1Be is for notifying that handwritten input data is being transmitted from the tablet terminal 1.

[0017] 2 and 3, a magnetic sheet 11 is placed in the handwriting input area of ​​the tablet terminal 1. Below the magnetic sheet 11, a position detection sensor 12 is disposed so as to overlap with the magnetic sheet 11 in a direction perpendicular to the surface of the tablet terminal 1.

[0018] As shown in Fig. 3(A), the magnetic sheet 11 is formed in a sheet shape by confining a large number of microcapsules 113, each containing magnetic material powder, such as iron powder 113Fe (shown as black dots in Figs. 3(A) and 3(B)), in a migratory state, in the gap between a sheet-shaped resin substrate 111 and a sheet-shaped resin substrate 112 made of, for example, PET (Polyethylene Terephthalate). In this case, at least the sheet-shaped resin substrate 111 is made of a transparent material. For example, the magnetic sheet used in the Clean Note Kaite manufactured by Plus Corporation can be used as this magnetic sheet 11.

[0019] In this embodiment, the surface 111a of the sheet-shaped resin base material 111 of the magnetic sheet 11 serves as the handwriting input surface 1A, as shown in Figures 2 and 3(A). When no magnetic pole is in proximity to or in contact with the magnetic sheet 11, the iron powder 113Fe in each microcapsule 113 is present in random, random positions as shown in Figure 3(B), and the surface of the magnetic sheet 11, i.e., the handwriting input surface 1A, is entirely a predetermined background color, for example, white.

[0020] When a magnetic pole approaches or comes into contact with the surface 111a of the sheet-shaped resin substrate 111 of the magnetic sheet 11, the iron powder 113Fe in the microcapsules 113 near the position where the magnetic pole approached or came into contact is attracted toward the magnetic pole, as shown in FIG. 3(A). Therefore, at the position where the magnetic pole approached or came into contact, the surface of the magnetic sheet 11, i.e., the handwriting input surface 1A, takes on the color of the iron powder 113Fe, for example, black. The position of the iron powder 113Fe in the microcapsules 113 is maintained even if the magnetic pole moves away. Therefore, when a magnetic pole that is approaching or in contact with the surface of the magnetic sheet 11 moves, the trajectory of its movement appears as a black line on the surface of the magnetic sheet 11.

[0021] The handwriting input device of this embodiment is equipped with an eraser 3 that returns the state of the iron powder 113Fe in the microcapsules 113 magnetically attracted to the surface of the magnetic sheet 11 of the tablet terminal 1 to the irregularly positioned state shown in Fig. 3(B). As is well known, the eraser 3 is equipped with an eraser magnet, and can erase an entire area of ​​a predetermined size, and can also erase small parts of handwriting by using its corners.

[0022] As described above, the position detection sensor 12 is provided on the rear surface of the magnetic sheet 11, overlapping the magnetic sheet 11. The tablet terminal 1 is provided with a position detection device unit 13 including a position detection circuit and other electronic components, as will be described later, using the area behind the position detection sensor 12 and the area behind the operation panel unit 1B. In this embodiment, the position detection sensor 12 constitutes a part of the position detection device unit 13.

[0023] The position detection device 13 in this embodiment is of the electromagnetic induction type, and the position detection sensor 12 and the electronic pen 2 are coupled by electromagnetic induction to perform signal interaction as described below. Based on the signal interaction between the position detection sensor 12 and the electronic pen 2, the position detection device 13 detects the coordinate position on the handwriting input surface 1A indicated by the electronic pen 2.

[0024] 3A, in this embodiment, the position detection sensor 12 has electrode conductors arranged on a flexible sheet 121 made of an insulating material, and a plurality of loop coils are configured. In this embodiment, on the flexible sheet 121, a plurality of X-axis direction loop coils are arranged at a predetermined pitch in the horizontal direction (X-axis direction) of the handwriting input surface 1A, and a plurality of Y-axis direction loop coils are arranged at a predetermined pitch in the vertical direction (Y-axis direction).

[0025] In this embodiment, in order to avoid overlapping of the electrode conductors constituting the X-axis direction loop coil and the Y-axis direction loop coil, which are arranged in directions perpendicular to each other, as shown in Fig. 3(A), electrode conductors 122 and 123 are formed on the front and back surfaces of the flexible sheet 121, and the X-axis direction loop coil and the Y-axis direction loop coil are formed on the flexible sheet 121 by utilizing through holes (not shown) that penetrate the flexible sheet 121. Note that in Fig. 2, the electrode conductors 122 and 123 are shown as linear conductors on the flexible sheet 121 of the position detection sensor 12 for convenience, but in reality, loop coils are constituted (see Fig. 7 described later).

[0026] <Configuration example of electronic pen 2> In this embodiment, as described above, the electronic pen 2 uses an electromagnetic induction system to send and receive signals to and from the position detection sensor 12 of the position detection device 13 of the tablet terminal 1, thereby causing the position detection device 13 of the tablet terminal 1 to detect its indicated position. The mechanical configuration of the electronic pen 2 in this embodiment can be similar to that of a known electromagnetic induction system electronic pen, except that a magnet portion and a yoke portion are provided at the pen tip of the core body 213. Therefore, only the configuration of the main parts of the electronic pen 2 will be described here, and a description of the configuration of other parts will be omitted.

[0027] 1, the electronic pen 2 of this embodiment includes an electronic pen main body 21 on one axial opening 20a side of a hollow portion of a cylindrical housing 20 made of, for example, resin. The electronic pen main body 21 includes a coil 211, a magnetic core around which the coil 211 is wound, a ferrite core 212 in this example, a core body 213, a writing pressure detection unit 214, and a capacitor 215 that forms a resonant circuit together with the coil 211.

[0028] 4A and 4B are diagrams illustrating an example of the configuration of the electronic pen main body 21. In the electronic pen main body 21 of this embodiment, as shown in Fig. 4A, the side opposite to the pen tip side of the ferrite core 212 around which the coil 211 is wound is coupled to a cylindrical body 216 made of, for example, resin.

[0029] 4(A), the ferrite core 212 in this example is, for example, a cylindrical ferrite material, with an axial through-hole 212a formed therein with a predetermined diameter r1 (for example, r1=1 mm) for inserting the core body 213. A tapered portion 212b that gradually tapers down is formed on the pen tip side of the ferrite core 212, and is configured to make the magnetic coupling with the position detection sensor 12 of the position detection device unit 13 stronger than when the tapered portion 212b is not present.

[0030] In this embodiment, a writing pressure detection unit 214 is provided near the joint between the cylindrical body 216 and the ferrite core 212. The writing pressure detection unit 214 is configured using a semiconductor element that changes capacitance in response to writing pressure, as disclosed in Japanese Patent Application Laid-Open No. 2013-161307, for example. Note that the writing pressure detection unit 214 can also be configured as a variable capacitance capacitor that changes capacitance in response to writing pressure, using a writing pressure detection means with a well-known mechanical configuration, as disclosed in Patent Document JP-A-2011-186803, for example.

[0031] A printed circuit board 217 is further housed within the cylindrical body portion 216. A capacitor 215 is provided on the printed circuit board 217, which is connected in parallel to the coil 211 to form a resonance circuit. The variable capacitance capacitor formed in the pen pressure detection portion 214 is connected in parallel to the capacitor 215 formed on the printed circuit board 217, to form part of the resonance circuit.

[0032] 4(B), the side of ferrite core 212 opposite the pen tip side is fitted into recess 216a provided in cylindrical body portion 216, thereby connecting ferrite core 212 to cylindrical body portion 216. Although not shown in the drawing, when ferrite core 212 is connected to cylindrical body portion 216, one end 211a and the other end 211b of coil 211 are electrically connected in parallel to capacitor 215 provided on printed circuit board 217 of cylindrical body portion 216.

[0033] In this embodiment, the core body 213 is rod-shaped and has a diameter smaller than the inner diameter r1 of the through-hole 212a of the ferrite core 212, and as will be described in detail later, has a magnet portion and a yoke portion provided at the pen tip. The length of the core body 213 in the axial direction is longer than the length of the ferrite core 212 in the axial direction. Note that in Figures 4(B) and 3(A), the portion of the pen tip part of the core body 213 where the yoke portion is provided is clearly shown as a portion that protrudes in a direction intersecting the axial direction.

[0034] 4(B), the core body 213 is inserted through the through-hole 212a of the ferrite core 212, and the tail end 213b is fitted into the fitting hole 214a of the writing pressure detection unit 214, thereby directly fitting to the writing pressure detection unit 214. In this fitted state, the core body 213 is in a state in which the pen tip portion protrudes from the opening on the tip side of the ferrite core 212. This makes the magnetic pole on the pen tip portion 213a side of the core body 213 located farther away from the end of the ferrite core 212 on the pen tip side.

[0035] 4(B), in this embodiment, the pen tip portion 213a of the core body 213, together with a part of the pen tip side of the ferrite core 212, is configured to protrude to the outside from the opening 20a of the housing 20 of the electronic pen 2. This allows the writing pressure applied to the pen tip portion 213a of the core body 213 to be directly transmitted to the writing pressure detection unit.

[0036] In this embodiment, the electronic pen 2 receives an AC signal of frequency f0 transmitted through the position detection sensor 12 of the position detection device unit 13 at a resonant circuit via electromagnetic induction coupling. The resonant circuit of the electronic pen 2 then feeds back the received AC signal to the position detection sensor 12 via electromagnetic induction coupling. The position detection device unit 13 detects the position on the position detection sensor 12 of the AC signal fed back from the electronic pen 2, thereby detecting the position pointed by the electronic pen 2. The position detection device unit 13 also detects a change in the frequency or phase of the AC signal received from the electronic pen 2, thereby detecting the writing pressure applied to the electronic pen 2.

[0037] In order to ensure that the AC signal interaction between the electronic pen 2 and the position detection sensor 12 as described above can be carried out smoothly with as little energy loss as possible, the resonant frequency of the resonant circuit of the electronic pen 2 is selected to be equal to the frequency f0 of the AC signal from the position detection device unit 13.

[0038] <Configuration example of core body 213> Fig. 5 is a diagram illustrating an example of the configuration of the core body 213 of the electronic pen 2 of this embodiment. As shown in Fig. 5, the core body 213 is roughly composed of three parts: a pen tip side shaft portion 213A (Fig. 5(A)), a rear end side shaft portion 213B (Fig. 5(B)), and a reinforcing pipe 213C (Fig. 5(C)).

[0039] As shown in Figure 5(A), the pen tip side shaft portion 213A consists of a joint portion A1, a yoke portion A2, and a magnet portion A3. The joint portion A1 is cylindrically formed from PEEK (Poly Ether Ether Ketone) resin, which has excellent impact resistance and excellent insulating and dielectric properties over a wide frequency range, and consists of a shaft portion A11 and a tip portion A12 with an outer diameter longer than that of the shaft portion A11. Therefore, the bottom surface of the tip portion A12 has a protruding portion A1T that protrudes from the outer edge of the shaft portion A11, and this portion functions as a positioning portion.

[0040] The front end portion A12 is a cup-shaped portion with an opening at the front end and a recess formed on the rear end side. The yoke portion A2 is attached to the recess of the front end portion A12. The yoke portion A2 has a cylindrical appearance, but has an opening and a recess formed inside, making it cup-shaped. The yoke portion A2 is fitted and fixed into the recess of the front end portion A12 with the opening exposed on the front end side. The yoke portion A2 is a soft iron member that forms part of the magnetic circuit and controls the path of the magnetic flux.

[0041] A cylindrical magnet A3 is fitted and fixed in place in the recess of the yoke A2. One tip of the magnet A3 protrudes from the opening of the yoke A2. The side of the magnet A3 protruding from the opening of the yoke A2 is the north pole and the opposite side is the south pole. The magnet A3 and the yoke A2 form a magnetic circuit. As will be described in more detail later, the yoke A2 acts to bring the south pole of the magnet A3 closer to the north pole, thereby controlling the path of the magnetic flux generated by the magnet A3. In this way, the tip A12 of the joint A1, the yoke A2, and the magnet A3 form the pen tip 213a of the core 213.

[0042] The rear end shaft portion 213B is formed in a cylindrical shape from PEEK resin and comprises a shaft portion B1, a protruding portion B2, and a fitting portion B3. The protruding portion B2 protrudes from the outer edges of the shaft portion B1 and the fitting portion B3 and functions as a positioning portion. The portion rearward of the protruding portion B2 is the fitting portion B3, which fits into the fitting hole 214a of the writing pressure detection unit 214. A protrusion is provided on the side of the fitting portion B3 to prevent it from easily falling out when fitted into the fitting hole 214a of the writing pressure detection unit 214.

[0043] The reinforcing pipe 213C is a hollow cylindrical tube made of metal such as stainless steel. The inner diameter of the reinforcing pipe 213C is the same as or slightly shorter than the outer diameters of the shaft portion A11 of the joint portion A1 of the nib-side shaft portion 213A and the shaft portion B1 of the rear-end-side shaft portion 213B. The outer diameter of the reinforcing pipe 213C is also the same as the outer diameters of the tip portion A12 of the joint portion A1 of the nib-side shaft portion 213A and the protruding portion B2 of the rear-end-side shaft portion 213B.

[0044] The shaft portion A11 of the nib-side shaft portion 213A is inserted and pressed into the tip opening Hf of the reinforcing pipe 213C, and the protruding portion A1T of the tip portion A12 of the nib-side shaft portion 213A abuts against the tip face Cf of the reinforcing pipe 213C and are fixed in place. Also, the shaft portion B1 of the rear-end-side shaft portion 213B is inserted and pressed into the rear-end opening Hb of the reinforcing pipe 213C, and the nib-side end face B2T of the protruding portion B2 of the rear-end-side shaft portion 213B abuts against the rear end face Cb of the reinforcing pipe 213C and are fixed in place.

[0045] In this way, the pen tip side shaft portion 213A is inserted into the front side of the reinforcing pipe 213C, and the rear end side shaft portion 213B is inserted into the rear side of the reinforcing pipe 213C, and the three members are integrated to form a single core body 213. In this case, shaft portion A11 of the pen tip side shaft portion 213A and shaft portion B1 of the rear end side shaft portion 213B are located inside the reinforcing pipe 213C, so the overall strength of the core body 213 can be increased.

[0046] 5, the core body 213 has a magnet portion A3 and a yoke portion A2 provided at the tip portion A12 of the joint portion A1 of the pen tip side shaft portion 213A. With this configuration, the magnetic field generated by the magnet portion A3 acts efficiently on the magnetic sheet 11 without affecting the position indication by the electronic pen 2. Because the DC magnetic field does not reach the rear end portion of the core body 213, the AC magnetic field does not affect the coil 211 and ferrite core 212 on the rear end side.

[0047] 6A and 6B are diagrams illustrating the magnetic field generated by the magnetic circuit configured in the core body 213 of the electronic pen 2. FIG. 6A is a diagram illustrating an example of a magnetic circuit formed by a magnet MG and a cup-shaped yoke YK. When the magnet MG is placed inside the cup-shaped yoke YK with the north pole positioned on the opening side as shown in FIG. 6A, the south pole is brought close to the north pole by the function of the yoke YK. This controls the path of the magnetic flux, and the magnetic field lines from the north pole of the magnet MG form a magnetic circuit that passes through the yoke YK and enters the south pole of the magnet MG. This suppresses the incidence of magnetic flux from space on the south pole of the magnet MG.

[0048] A similar configuration is mounted on the pen tip of the electronic pen 2. That is, as shown in FIG. 6(B), a cup-shaped yoke A2 is fixed to the tip A12 of the pen tip-side shaft 213A, and the magnet A3 is fixed within this yoke A2 so that its tip, which is the north pole, is exposed. As a result, as shown in FIG. 6(B), a magnetic circuit is formed in which magnetic field lines from the north pole of the magnet A3 pass through the yoke A2 and enter the south pole of the magnet A3. This allows the magnetic flux of the magnet A3 to be controlled to affect only a very limited range on the tip side, as indicated by the dotted circle in FIG. 6(B), without affecting the magnetic field of the magnet A3 on the south pole side of the magnet A3. Therefore, the magnetic flux generated by the magnet A3 acts efficiently on the magnetic sheet 11 without affecting the position indication by the electronic pen 2.

[0049] For example, as shown in Fig. 6(C), consider the case where the core MgT itself that penetrates the ferrite core 212 in the axial direction is a magnet. When the core MgT made of a magnet is inserted into the through-hole 212a of the ferrite core 212, the magnetic characteristics of the ferrite core 212 are reduced by the DC magnetic field of the magnet, and as a result, the inductance value of the coil 211 decreases. Therefore, even if the resonance frequency of the resonance circuit composed of the coil 211 and the capacitor 215 is selected to be equal to the frequency f0 of the AC signal transmitted from the position detection device unit 13, the effective resonance frequency will be higher than the frequency f0 by the reduction amount Δf of the inductance of the coil 211 due to the core MgT made of a magnet.

[0050] Therefore, when constructing the electronic pen using the core MgT made of a magnet, it is necessary to select the resonance frequency of the resonance circuit composed of the coil 211 and the capacitor 215 to be a frequency f1 (<f0) lower than the frequency f0 of the AC signal transmitted from the position detection device unit 13, taking into account in advance the reduction amount of the inductance of the coil 211 due to the core MgT made of a magnet. By doing so, in the state where the core MgT is inserted into the through-hole 212a of the ferrite core 212, the effective resonance frequency of the resonance circuit composed of the coil 211 and the capacitor 215 becomes equal to the frequency f0.

[0051] However, in the case of the electronic pen 2 of this embodiment, since the pen tip portion is configured to include the magnet portion A3 and the yoke portion A2, even if the core 213 is inserted into the ferrite core 212, the inductance of the coil 211 does not decrease. Therefore, in the position detection device unit 13, there is no need to take special measures such as shifting the resonance frequency of the electronic pen 2 in advance in order to detect the coordinate position indicated by the electronic pen 2 with the same accuracy as before.

[0052] In the configuration shown in FIG. 6(C), the magnetic flux range is so wide that, as indicated by the dotted circle, the iron powder 113Fe in the microcapsules 113 of the magnetic sheet 11 may react and produce an unintended drawing before the MgT core comes into contact with the handwriting input surface 1A. In this case, the magnetic flux acts over a wide range, resulting in poor contrast of the drawing, such as blurring the outer edges of the drawn lines. However, in the case of the electronic pen 2 of this embodiment, as indicated by the dotted circle in FIG. 6(B), the magnetic flux generated by the magnet portion A3 can be narrowed to an extremely narrow range by the function of the yoke portion A2. This prevents drawing that the user does not intend and improves the contrast of the drawing.

[0053] Furthermore, in the electronic pen 2 of this embodiment, when the pen tip portion 213a of the core body 213 of the electronic pen main body 21 protrudes to the outside during use, not only the core body 213 but also a part of the ferrite core 212 protrudes from the opening 20a of the housing 20, as shown in Figure 4(B), and the distance from the tip of the tapered portion 212b of the ferrite core 212 to the input surface of the position detection sensor 12 becomes shorter.

[0054] Therefore, the electronic pen 2 of this embodiment has a stronger electromagnetic coupling with the position detection sensor 12 than a conventional electronic pen in which the ferrite core 212 remains inside the hollow portion of the housing 20. Furthermore, in this embodiment, the tip end side of the ferrite core 212 is formed into a tapered portion 212b, so that the cross-sectional area of ​​the tip end of the ferrite core 212 is smaller, the magnetic flux density is increased, and a stronger electromagnetic coupling with the position detection sensor 12 is achieved.

[0055] Therefore, even when the electronic pen 2 of this embodiment is made thinner, it can be strongly electromagnetically coupled to the position detection sensor 12, and the position detection device unit 13 can detect the position indicated by the electronic pen 2 with high sensitivity. Of course, like conventional electronic pens, the ferrite core 212 may be configured to remain within the hollow portion of the housing 20, and the pen tip portion 213a of the core body 213 may protrude from the housing 20. Since the magnetic field generated by the magnet portion A3 of the pen tip portion 213a does not affect the AC magnetic field used for position detection, there is no problem in detecting the indicated position even in the case of an electronic pen with a conventional configuration.

[0056] <Installation of eraser function part> 1, an eraser functional unit 22 can also be provided on the rear end surface 20b of the electronic pen 2 equipped with the electronic pen body 21, as shown by a dotted line. The eraser functional unit 22 can be configured in the same manner as the electronic pen body 21 described above. That is, a core body configured in the same manner as the core body 213 described with reference to FIG. 5 is provided in a through hole of a ferrite core around which a coil is wound. In this case, the magnet portion of the pen tip of the core body is fixed so that its south pole side protrudes from the opening of the cup-shaped yoke portion and its north pole side is located on the bottom side of the yoke portion. That is, a core body is used in which the magnetic pole of the magnet portion provided at the pen tip is reversed to that in the electronic pen body 21.

[0057] Suppose the tip of the core of the eraser functional part 22 configured in this way is brought close to or into contact with the writing trajectory appearing on the surface of the magnetic sheet 11 so as to trace it. That is, the writing trajectory is displayed on the surface of the magnetic sheet 11 by the iron powder 113Fe in the microcapsules 113 that has been attracted to the N-pole magnetic pole of the pen tip part 213a of the core 213 of the electronic pen main body 21 and magnetized to the S-pole. This is then moved away from the surface of the magnetic sheet 11 by the S-pole magnetic pole of the tip of the core of the eraser functional part, thereby erasing the writing trajectory that had appeared.

[0058] Furthermore, in the position detection device unit 13 of the handwriting input device of this embodiment, in addition to the AC signal of frequency f0 for detecting handwriting input described above, an AC signal of frequency f2 (≠ f0), which can be clearly distinguished from frequency f0 and detects a feedback signal, is transmitted to the electronic pen 2 via the position detection sensor 12 for use in detecting an erase instruction. The coil of the eraser function unit of the electronic pen 2 is connected in parallel with a capacitor to form a resonant circuit. However, the resonant frequency of this resonant circuit is configured to be equal to the frequency f2 of the AC signal for detecting the erase instruction described above, so that the AC signal of frequency f2 from the position detection device unit 13 is received and fed back to the position detection sensor 12.

[0059] When the user brings the core of the eraser function part of the electronic pen 2 close to or in contact with the surface of the magnetic sheet 11, an AC signal for detecting an erase instruction is received from the position detection device part 13, and an AC signal of frequency f2 is fed back via the resonant circuit of the eraser function part.The position detection device part 13 receives the feedback signal via the position detection sensor 12 and detects the received position on the position detection sensor 12, thereby detecting the coordinate position where the erase instruction was given.

[0060] Thus, in the handwriting input device of this embodiment, by bringing the pen tip portion 213a of the electronic pen body portion 21 of the electronic pen 2 close to or in contact with the handwriting input surface 1A, the writing trajectory can be displayed on the surface of the magnetic sheet 11, and the electronic data of the writing trajectory (writing data and writing pressure data) can be detected and stored.

[0061] In this way, when an eraser function unit is provided in the electronic pen 2, the tip of the core of the eraser function unit can be brought close to or into contact with the handwriting input surface 1A and moved so as to follow the writing path displayed on the surface of the magnetic sheet 11, thereby erasing the writing path displayed on the surface of the magnetic sheet 11 and deleting the corresponding writing data and writing pressure data from the memory unit.

[0062] In addition, when the writing marks displayed on the magnetic sheet 11 are erased using the eraser 3 for the magnetic sheet 11, the position detection device unit 13 cannot detect the position of the eraser 3, and therefore the writing data and writing pressure data stored in the position detection device unit 13 are not erased.

[0063] Furthermore, when writing with the electronic pen main body 21 and erasing handwriting with the eraser function unit, a frequency f0 for detecting handwriting input and a frequency f2 for erasing input are used. For this reason, when the position detection device 13 is used as a reference, a transmission / reception period (transmission period and reception period) of an AC signal with the frequency f0 for detecting handwriting input and a transmission / reception period (transmission period and reception period) of an AC signal with the frequency f2 for erasing input are provided in a time-division manner.

[0064] The electronic pen body 21 and the eraser function unit 22 are equipped with writing pressure detection units that transmit signals containing writing pressure information. Therefore, during the period in which an AC signal of frequency f0 for detecting handwriting input is transmitted, the position detection device 13 transmits a signal of frequency f0. Due to a corresponding resonance effect, during the period in which an AC signal of frequency f0 for detecting handwriting input is received, the electronic pen body 21 transmits a signal of frequency f0 before the pen tip 213a comes into contact with the operation surface. Furthermore, during the period in which an AC signal of frequency f0 for detecting handwriting input is received, the electronic pen body 21 transmits a signal of frequency f0' containing writing pressure information when the pen tip 213a is in contact with the operation surface.

[0065] Similarly, during the period in which an AC signal of frequency f2 for erasure input is transmitted, the position detection device unit 13 transmits a signal of frequency f2. Due to the corresponding resonance action, during the period in which an AC signal of frequency f2 for erasure input detection is received, the eraser function unit 22 transmits a signal of frequency f2 before the pen tip comes into contact with the operation surface. Also, during the period in which an AC signal of frequency f2 for erasure input detection is received, the eraser function unit 22 transmits a signal of frequency f2' including writing pressure information when the pen tip is in contact with the operation surface.

[0066] This prevents detection of AC signals with frequencies f2 and f2' for erasure input during the period when an AC signal with frequency f0 for detecting handwriting is transmitted and received, allowing only writing to be performed.Furthermore, during the period when an AC signal with frequency f2 for detecting erasure input is transmitted and received, detection of AC signals with frequencies f0 and f0' for handwriting input can be prevented, allowing only erasure of handwriting to be performed.

[0067] In this way, when both writing with the electronic pen main body 21 and erasing handwriting with the eraser function unit are possible, the electronic pen main body 21 and the eraser function unit can be configured in the same way, but the following three conditions must be satisfied. First, the magnetic poles of the tips of the cores of the electronic pen main body 21 and the eraser function unit are reversed. Second, the resonant frequencies of the electronic pen main body 21 and the eraser function unit are set to different, clearly distinguishable frequencies. Furthermore, on the position detection device side, by time-sharing a period for transmitting and receiving an AC signal with a frequency for detecting handwriting input and a period for transmitting and receiving an AC signal with a frequency for erasing input, both writing with the electronic pen main body 21 and erasing handwriting with the eraser function unit become possible.

[0068] <Configuration example of electronic circuit of handwriting input device according to embodiment> 7 is a diagram showing the electronic circuit configuration of the tablet terminal 1 and electronic pen 2 that constitute the handwriting input device of this embodiment. As described above, it is also possible to provide an eraser function unit on the rear end surface 20b of the electronic pen 2. However, for simplicity of explanation, the configuration and operation of the tablet terminal will be described below using the case of handwriting input via the electronic pen main body 21 as an example.

[0069] As shown in FIG. 7, the electronic pen 2 includes a resonant circuit RCp of the electronic pen body 21, which is configured by a coil 211, a capacitor 215, and a variable capacitor 214C that is configured by the writing pressure detection unit 214.

[0070] When the pen tip portion 213a of the core body 213 of the electronic pen main body 21 of the electronic pen 2 is brought close to or into contact with the handwriting input surface 1A of the tablet terminal 1, the resonant circuit RCp is electromagnetically inductively coupled with the position detection sensor 12 to exchange AC signals of frequency f0.

[0071] An X-axis direction loop coil group 124X and a Y-axis direction loop coil group 125Y are formed in the position detection sensor 12 of the position detection device unit 13. The position detection circuit 130 of the position detection device unit 13 transmits a signal by electromagnetic coupling to the resonant circuit RCp of the electronic pen 2 through the X-axis direction loop coil group 124X and the Y-axis direction loop coil group 125Y of the position detection sensor 12. The position detection circuit 130 transmits an AC signal of frequency f0 to the electronic pen 2 through the position detection sensor 12.

[0072] When the pen tip portion 213a of the core body 213 of the electronic pen main body portion 21 of the electronic pen 2 is brought close to or into contact with the handwriting input surface 1A of the tablet terminal 1, the resonant circuit RCp receives an AC signal of frequency f0 from the position detection sensor 12 and also feeds the AC signal back from this resonant circuit RCp to the position detection sensor 12.

[0073] The position detection circuit 130 receives a feedback signal from the resonant circuit RCp of the electronic pen 2 via the position detection sensor 12 by electromagnetic coupling. Then, the position detection circuit 130 detects the position on the position detection sensor 12 designated by the electronic pen 2 from the position on the position detection sensor 12 where the received signal is detected. The position detection circuit 130 also detects a change in the resonant frequency of the resonant circuit RCp by detecting a phase change in the signal received from the electronic pen 2, and thereby detects the writing pressure applied to the core 213 of the electronic pen main body 21 of the electronic pen 2.

[0074] The position detection circuit 130 is provided with a position detection control unit 137 that controls the position detection process and the writing pressure detection process described below. An oscillator 131 generates a signal with an oscillation frequency f0. The position detection circuit 130 is provided with a selection circuit 126 to which the X-axis loop coil group 124X and the Y-axis loop coil group 125Y of the position detection sensor 12 are connected. The selection circuit 126 sequentially selects one of the two loop coil groups 124X, 125Y to transmit a signal to the resonant circuit RCp and receive a signal fed back from the resonant circuit RCp.

[0075] A switching circuit 133, which is switchably controlled by a position detection control unit 137, is connected to the selection circuit 126. When this switching circuit 133 is connected to a transmission side terminal T, an AC signal is supplied from an oscillator 131 to the selection circuit 126, and when it is connected to a reception side terminal R, a signal from the selection circuit 126 is supplied to a pointed position detection circuit 135 and a writing pressure detection circuit 136 via an amplifier 134.

[0076] The pointed-position detection circuit 135 detects the induced voltage generated in the loop coil of the position detection sensor 12, i.e., the received signal, converts the detected output signal into a digital signal, and outputs it to the position detection control unit 137. The position detection control unit 137 calculates the coordinate values ​​of the pointed-position in the X-axis and Y-axis directions of the electronic pen 2 based on the digital signal from the pointed-position detection circuit 135, i.e., the level of the voltage value of the induced voltage generated in each loop coil.

[0077] On the other hand, the writing pressure detection circuit 136 synchronously detects the output signal of the amplifier 134 with the AC signal from the oscillator 131 to obtain a signal with a level corresponding to the phase difference (frequency shift) therebetween, converts the signal corresponding to the phase difference (frequency shift) into a digital signal, and outputs it to the position detection control unit 137. The position detection control unit 137 detects the writing pressure applied to the core 213 of the electronic pen main body 21 of the electronic pen 2 based on the digital signal from the writing pressure detection circuit 136, i.e., the level of the signal corresponding to the phase difference (frequency shift) between the transmitted radio wave and the received radio wave.

[0078] The position detection control unit 137 supplies the detected coordinate data of the position pointed to by the electronic pen 2 to the control unit 140 as writing data together with the detected writing pressure data.

[0079] The control unit 140 includes a memory 141 and a wireless communication unit 142. Although not shown, the control unit 140 also includes a rechargeable battery, a charging circuit, and a power supply circuit. An operation unit 143 including a power button 1Ba, a handwriting input end button 1Bb, and an information transmission button 1Bc, which are provided on the operation panel unit 1B, is connected to the control unit 140, and an indicator unit 144 including a power indicator 1Bd and a communication indicator 1Be is also connected to the control unit 140.

[0080] When the power button 1Ba of the operation unit 143 is pressed to turn it on, the control unit 140 generates a power supply voltage Vcc and supplies it to each unit, putting the tablet terminal 1 into an operating state. At this time, the control unit 140 turns on the power indicator 1Bd to notify the user that the power is on. When the power button 1Ba is pressed again, an instruction to turn the power off is issued, and the control unit 140 stops supplying the power supply voltage Vcc to each unit, enters an inactive state, and the power indicator 1Bd is turned off.

[0081] The control unit 140 stores the handwriting data and writing pressure data received from the position detection control unit 137 in the memory 141. When the control unit 140 detects that the user has pressed the handwriting input end button 1Bb, it stores the group of handwriting data and writing pressure data that has been stored in the memory 141 up to that point as one page of data. At this time, page identification information is assigned to the one page of data.

[0082] Therefore, after pressing the handwriting input end button 1Bb, the user uses the eraser 3 to erase the handwriting that appears on the entire surface of the magnetic sheet 11, and then performs new handwriting input. At this time, the eraser 3 is designed to erase only the handwriting that appears on the surface of the magnetic sheet 11, so the control unit 140 does not erase the handwriting data stored in memory 141 on a page-by-page basis.

[0083] After erasing all of the handwriting that appears on the surface of the magnetic sheet 11 in this manner, the user uses the electronic pen 2 to input new handwriting, and the control unit 140 stores the new handwriting data and writing pressure data in the memory 141. Then, when the user presses the handwriting input end button 1Bb, the newly stored handwriting data and writing pressure data in the memory 141 are stored in the memory 141 as data of a different page.

[0084] In this embodiment, the control unit 140 includes a wireless communication unit 142 and is capable of wireless communication with a server device, such as a computer. In an environment where wireless communication with the server device is possible, when a user presses the information transmission button 1Bc on the operation panel 1B of the tablet terminal 1, the control unit 140 transmits the handwriting data and writing pressure data stored in the memory 141 for each page to the server device and erases the memory 141. At this time, while the control unit 140 is transmitting the handwriting data and writing pressure data to the server device, the control unit 140 lights up the communication indicator 1Be to notify the user that the handwriting data and writing pressure data are being transmitted to the server device.

[0085] The control unit 140 may be configured so that the handwriting data and writing pressure data for each page stored in the memory 141 are automatically transmitted to the server device when the handwriting input end button 1Bb is pressed, rather than the user operating the information transmission button 1Bc to transmit the page-by-page handwriting data and writing pressure data stored in the memory 141 to the server device. In this case, the information transmission button 1Bc does not need to be provided.

[0086] <Effects of the embodiment> According to the handwriting input device of the above-described embodiment, by writing on the handwriting input surface 1A with the electronic pen 2, electronic data of handwriting input consisting of handwriting data and writing pressure data can be obtained in the same manner as in the conventional device. Furthermore, the electronic pen 2 includes a core body 213 having a magnet portion A3 and a yoke portion A2 at the pen tip. Therefore, the magnetic sheet 11, which can display handwriting by the action of a magnetic field, can be used as the display unit, eliminating the need for a display panel such as an LCD, and realizing an inexpensive handwriting input device.

[0087] Furthermore, by providing the magnet portion A3 and the yoke portion A2 in the pen tip portion 213a of the core body 213, a magnetic circuit is formed, and the magnetic field can be limited to affecting only an extremely limited range. Therefore, the portions of the core body 213 other than the pen tip portion 213a are not magnets, so the core body 213 does not affect the AC magnetic field (alternating magnetic field) for position indication, and there is no need to consider a shift in the resonant frequency, etc.

[0088] Furthermore, although magnets are generally vulnerable to impact, the magnet portion A3 is only exposed at a very small portion of the tip of the pen tip portion 213a, making it possible to realize a core body 213 that is resistant to impact. As a result, even if the electronic pen 2 is dropped while being carried around, the core body 213 will not easily break. Furthermore, by using the magnetic sheet 11, handwriting can be easily erased using the eraser 3 or, for example, an eraser function portion provided on the electronic pen 2. Therefore, it is convenient to carry and has the advantage of not producing eraser dust as with paper.

[0089] Furthermore, the electronic pen 2 constituting the handwriting input device of this embodiment can be constructed at low cost because it can be configured similarly to existing electromagnetic induction type electronic pens, except that the pen tip 213a of the core body 213 is provided with the magnet portion A3 and the yoke portion A2. Furthermore, the position detection sensor 12 and the position detection circuit 130 of the position detection device portion of the handwriting input device of the above-mentioned embodiment can directly use existing electromagnetic induction type position detection sensors and position detection circuits.

[0090] [Variations] Although the core body 213 of the electronic pen 2 in the above-described embodiment is configured by the pen tip side shaft portion 213A, the rear end side shaft portion 213B, and the reinforcing pipe 213C, the present invention is not limited to this. For example, a core body can be configured by providing a magnet portion A3 and a yoke portion A2 at the tip of a single shaft portion made of various materials such as hard resins such as POM (polyacetal), and this can be used as the core body for the electronic pen 2.

[0091] Alternatively, a core body can be formed by providing a magnet portion A3 and a yoke portion A2 at the tip of a single shaft portion formed from various materials such as hard resin, and the portion of this core body excluding the pen tip portion and rear end portion can be reinforced with a reinforcing pipe to form a core body for the electronic pen 2. In other words, if the core body 213 is configured such that the magnet portion A3 and the yoke portion A2 are provided at the pen tip portion, the other portions can be configured using various materials other than magnets that may affect the magnetic field (AC magnetic field) for position indication.

[0092] Also, a guide pipe penetrating the through hole 212a of the ferrite core 212 may be provided in the through hole 212a, and the core body 213 may be configured to pass through the inside of this guide pipe. This can protect the ferrite core 212 and facilitate the sliding movement of the core body 213 in the axial direction. Furthermore, when the core body is configured not to be provided with a reinforcing pipe 213C, this also contributes to the protection of the core body.

[0093] The magnet portion A3 and the yoke portion A2 can have various sizes and shapes. For example, the tip of the magnet portion A3 can be machined into a hemispherical shape. The magnet portion A3 and the yoke portion A2 can also be formed into a polygonal prism shape. Various other modifications are possible. [Explanation of symbols]

[0094] 1...tablet terminal, 1A...handwriting input surface, 1B...operation panel section, 2...electronic pen, 3...eraser, 11...magnetic sheet, 12...position detection sensor, 13...position detection device section, 21...electronic pen main body section, 211...coil, 212...ferrite core, 212a...through hole, 213...core body, 213a...pen tip section, 213A...pen tip side shaft section, A1...joint section, A11...shaft section, A12...tip section, A1T...extension section, A2...yoke section, A3...magnet section, 213B...rear end side shaft section, B1...shaft section, B2...projection section, B2T...pen tip side end surface, B3...fitting section, 213C...reinforcing pipe, 214...pen pressure detection section, 215...capacitor

Claims

1. A handwriting input device including a position detection device and an electronic pen, The position detection device a magnetic sheet that changes color at a position where a magnetic pole approaches or comes into contact with the magnetic sheet; an electromagnetic induction type position detection sensor disposed under and overlapping the magnetic sheet; Equipped with The electronic pen is A coil and a magnetic core around which the coil is wound and which has a through hole in the axial direction; a capacitor that forms a resonant circuit together with the coil; a rod-shaped core body to be inserted into the through hole of the magnetic core, the core body having a magnet portion at a pen tip portion of the core body and a yoke portion for holding the magnet portion; Equipped with the position detection sensor detects the pen position of the electronic pen through electromagnetic induction coupling with a sensor signal having a frequency corresponding to a resonant frequency of the resonant circuit; The detected pen position is displayed based on the fact that the magnet portion arranged at the pen tip portion of the electronic pen causes a color change at a position on the magnetic sheet near the pen tip. A handwriting input device characterized by:

2. 2. The handwriting input device according to claim 1, the magnetic sheet has a microcapsule layer containing magnetic powder, At a position where the magnetic pole of the pen tip portion of the core body of the electronic pen approaches or comes into contact with the magnetic powder in the layer of the magnetic sheet, the magnetic powder is magnetically attracted to the magnetic pole, causing a color change at that position on the surface of the magnetic sheet. A handwriting input device characterized by:

3. 3. The handwriting input device according to claim 2, and an erasing member configured to return the powder in the microcapsules to their original positions in the vicinity of the positions in order to erase the color change at the positions on the magnetic sheet. A handwriting input device characterized by:

4. 2. The handwriting input device according to claim 1, The electronic pen further includes a magnet at the rear end of the electronic pen, the magnet having a magnetic polarity opposite to that of the magnet portion disposed at the pen tip portion of the core body. A handwriting input device characterized by:

Images