JP7180962B2 - Electronic pen and position detection system - Google Patents

Description

The present invention relates to an electronic pen that indicates a position to a position detection device that detects the indicated position, and a position detection system that includes the electronic pen and the position detection device.

2. Description of the Related Art With recent computerization, a position detection system including an electronic pen and a position detection device is used as an input device for digital equipment such as a personal computer. In electronic pens, it is important to be able to accurately indicate a position (coordinates) and appropriately detect writing pressure applied to the pen tip. For example, in order to input characters to a digital device through a position detection device with an electronic pen in the same way as writing letters or pictures on paper with a pencil, the subtle force applied to the tip of the electronic pen is required. This is because it must be possible to detect changes in (pen pressure).

Conventionally, there is a method of detecting writing pressure according to changes in inductance. In this method, a ferrite chip moves toward or away from a coil wound around ferrite according to writing pressure, and writing pressure is detected according to the changing inductance of the coil. There is also a method of detecting writing pressure using a variable capacitor. In this method, a variable-capacitance capacitor is constructed by sandwiching a dielectric between electrodes connected in parallel to a resonant circuit. Pen pressure is detected according to

In the case of the former method using inductance, the inductance changes when the electronic pen is tilted or the pen tip of the electronic pen is directed upward, which may cause erroneous detection of writing pressure. Therefore, in Patent Document 1 described later, a coil is wound and a spring or the like is provided between a ferrite core and another ferrite to provide a dead zone in which writing pressure is not detected, and when writing pressure is truly applied, Inventions are disclosed that allow this to be detected only by For this reason, in the case of the method using inductance, it may not be possible to accurately detect a slight writing pressure, and it is difficult to realize the delicate writing feeling of writing with a pencil on paper.

In the case of the latter method using a variable capacitance capacitor, even a slight writing pressure applied to the tip of the pen can be detected, so it is possible to realize a writing feel similar to that of writing with a pencil on paper, and is widely used in electronic pens. On the other hand, the configuration of the variable capacitor becomes somewhat complicated. In addition, the thickness of the dielectric that makes up the variable capacitor, the size of the electrodes that sandwich the dielectric, the hardness and shape of the conductive rubber that serves as the electrode that moves closer to and away from the dielectric, etc. It can be adjusted to obtain desired characteristics. However, this adjustment may take time.

As another writing pressure detection method, Patent Document 2 described later relates to an electronic pen equipped with a configuration for detecting writing pressure using a piezoelectric element (piezo element) that generates a voltage corresponding to the applied pressure. An invention is disclosed. Piezoelectric elements have a simple structure, and although the deformation (deviation) when pressure is applied is very small, the pressure detection range is extremely wide. It has the advantage of being easy.

JP 2013-191168 A JP-A-7-325658

As described above, the use of piezoelectric elements for writing pressure detection has both advantages and disadvantages. One disadvantage is that the relationship between applied pressure and output voltage is a steep linear change. That is, in the case of a piezoelectric element, when a pressure above a certain level is applied, the output voltage sharply increases with even a small amount of pressure applied thereafter. For this reason, it is difficult to form a change in writing pressure as in the case of writing a line on paper with a pencil.

In other words, if we consider the case of writing a line on paper with a pencil, graphite will remain on the paper when the pencil touches the paper. And while writing, even if the pencil is pressed against the paper to some extent, the change in appearance is small. Therefore, in order to achieve the same writing feeling as writing letters and pictures on paper with a pencil, the sensitivity is sufficiently high at the beginning of writing, and the detection sensitivity is gentle according to the writing pressure applied during writing ( not abrupt). However, it is difficult for a piezoelectric element to form an output that responds to changes in writing pressure with such characteristics.

Another disadvantage is that while piezoelectric elements are very simple in construction, they cannot be fine-tuned and customized in the same way as variable capacitors described above. The point is that In other words, it is difficult to apply the piezoelectric element to the electronic pen because the piezoelectric element cannot be finely adjusted so as to obtain desired characteristics regarding pen pressure detection. Moreover, in the case of a piezoelectric element, an output voltage cannot be obtained unless a certain amount of pressure, for example, a pressure of several grams, is applied. This point is also one of the reasons why it is not possible to realize a writing feeling such that even if the pencil touches the paper slightly, the graphite remains on the paper.

In view of the above, the present invention relates to an electronic pen and a position detection system comprising an electronic pen and a position detection device, which has a simple configuration, does not require various adjustments, and can be used to write letters or the like on paper with a pencil. The purpose is to achieve the same writing feel as

In order to solve the above problems,
The tip protrudes from the end of a pen-shaped housing provided with a housing-side locking portion inside, and is movable in the axial direction according to the writing pressure applied to the tip. a core body provided with a core body-side engaging portion;
a writing pressure detection unit disposed in the housing and pressed by the core;
an offset elastic member that biases the core toward the writing pressure detection unit by being sandwiched between the housing-side locking portion and the core-side locking portion;
The writing pressure detection unit is
A writing pressure detection element that outputs an electric signal according to the applied pressure, a first elastic member, and a second elastic member are provided in series in the axial direction,
The core body is positioned on the front end side of the writing pressure detection element in the axial direction, the first elastic member is positioned on the rear end side of the writing pressure detection element in the axial direction, and the first elastic member is positioned on the rear end side of the writing pressure detection element in the axial direction. The second elastic member is positioned on the rear end side of the elastic member in the axial direction,
When the writing pressure applied to the core body is less than a predetermined value, the first elastic member acts predominantly on the writing pressure detection element, and the writing pressure applied to the core body is reduced to a predetermined value. In the above case, the electronic pen is provided, wherein the first elastic member and the second elastic member act on the writing pressure detection element .

1A and 1B are diagrams showing an appearance of an electronic pen according to an embodiment and an appearance of a tablet information terminal in which information is input using the electronic pen; FIG. 4 is a diagram for explaining a configuration example of a writing pressure detection unit; FIG. FIG. 5 is a diagram for explaining bias characteristics of each component constituting the writing pressure detection unit and bias characteristics of the writing pressure detection unit as a whole; It is a figure for demonstrating the structural example of the principal part of the electronic pen of embodiment. 5A and 5B are graphs showing output characteristics of a pen pressure detection element and output characteristics of the entire pen pressure detection unit (FIG. 5B); FIG. 1 is a block diagram for explaining a schematic configuration of an electronic pen according to an embodiment; FIG. 1 is a block diagram for explaining a schematic configuration of a position detection device according to an embodiment; FIG. FIG. 10 is a diagram for explaining another configuration example of the writing pressure detection unit;

Embodiments of an electronic pen and a position forming system according to the present invention will be described below with reference to the drawings. A position detection system comprising an electronic pen and a position detection device includes, for example, an active electrostatic coupling system (AES (Active Electrostatic) system) and an electromagnetic induction system (EMR (Electro Magnetic Resonance technology) system). be. The present invention will be described by taking as an example a case where it is applied to an active electrostatic coupling system (AES (Active Electrostatic) system).

[Example of Appearance of Electronic Pen 1]
FIG. 1 shows the appearance of an electronic pen 1 of this embodiment and the appearance of a tablet information terminal 2 in which information is input using the electronic pen 1. As shown in FIG. The appearance of the electronic pen 1 has a configuration in which the tip portion 11 a of the core 11 protrudes from a pen-shaped housing 15 . Inside the housing 15, the core body 11 and the writing pressure detection unit 12 are arranged, although the details will be described later.

The core 11 is movable in the axial direction according to the writing pressure applied to the tip portion 11 a protruding from the housing 15 . That is, the core body 11 is configured to be pushed into or pushed out from the housing 15 according to the writing pressure. The core body 11 presses the writing pressure detection unit 12, and the writing pressure is detected by the writing pressure detection unit 12. The electronic pen 1 is positioned on the display screen 2D of the tablet information terminal 2. , and also sends out a signal that notifies the detected writing pressure.

On the other hand, the tablet information terminal 2 has a configuration in which a relatively large display screen 2D of a display device such as an LCD (Liquid Crystal Display) is exposed. On the back of the display screen 2D is a position detection device having a sensor unit corresponding to the entire surface of the display screen 2D so that the indicated position can be detected when the electronic pen 1 points to any position on the display screen 2D. 200 is installed.

It should be noted that the sensor section of the position detection device 200 may be provided on the back side (rear surface) of the display screen 2D, or may be provided on the front side (surface) thereof. In this example, the sensor section is configured to be transparent and provided on the upper side (front section) of the display screen 2D. A display device (such as an LCD) and a position detection device 200 are connected to the inside of the housing of the tablet information terminal 2, and an information processing device (not shown) that performs various types of information processing is mounted. .

As described above, the tablet information terminal 2 is an information processing device in which the position detection system including the electronic pen 1 and the position detection device 200 serves as a main input device. For example, a protective glass or the like is provided on the display screen 2D, and instructions can be input with the electronic pen 1 using the display screen 2D as an operation surface through the protective glass.

Assume that a position indication operation is performed with the electronic pen 1 on the display screen 2</b>D of the tablet information terminal 2 . In this case, the processing unit included in the position detection device 200 identifies the indicated position on the display screen 2D based on the detection output from the sensor section of the position detection device 200 provided on the surface of the display screen 2D. Information indicating the pointing position specified by the processing unit is supplied to the information processing device unit installed in the tablet information terminal 2, and processing can be performed accordingly.

[Configuration example of writing pressure detection unit 12]
The electronic pen 1 of this embodiment is characterized by the configuration of the writing pressure detection unit 12 . As described above, the writing pressure detection unit 12 appropriately detects the writing pressure when pressed by the core body 11 that moves in the axial direction according to the writing pressure applied to the tip portion 11a. is possible. The writing pressure detection unit 12 of this embodiment includes a writing pressure detection element and an elastic member for adjusting stepwise the writing pressure applied to the writing pressure detection element. . More specifically, in the embodiments described below, in order to adjust the pen pressure applied to the pen pressure detection element in two stages, two elastic members are arranged in parallel to the pen pressure detection element. A case of configuring the writing pressure detection unit 12 by arranging them will be described.

FIG. 2 is a diagram for explaining a configuration example of the writing pressure detection unit 12. As shown in FIG. FIG. 2 shows three typical configuration examples 12(1), 12(2), and 12(3) of the writing pressure detection unit 12. As shown in FIG. In any of the configuration examples, a writing pressure detection element 12a and 2 It is configured by providing two elastic members in parallel.

The writing pressure detection element 12a includes various elements such as a piezoelectric element, a gauge type pressure sensor element, and a variable capacitance capacitor chip (element) using MEMS (Micro Electro Mechanical Systems) technology. The simplest piezoelectric element can be realized by sandwiching a piezoelectric body such as crystal or ceramic between two electrodes, and can generate a voltage corresponding to the pressure applied to the piezoelectric body. is.

Gauge type pressure sensor elements include strain gauge type, metal gauge type, semiconductor gauge type, etc. All of them have, for example, four gauge resistors arranged on the surface of the diaphragm, and the resistance value of the gauge resistors changes depending on the pressure. This is used to measure pressure. A variable-capacitance capacitor element using MEMS technology is a variable-capacitance capacitor whose electrostatic capacity changes according to writing pressure, and is configured as a MEMS chip made of a semiconductor device having a micron-level structure.

Also, an element capable of detecting writing pressure (pressure) can be configured by using a combination of the techniques used for the above-described elements. As described above, there are various kinds of pen pressure detecting elements. In this specification, the pen pressure detecting element 12a means a minimum unit member capable of outputting an electric signal corresponding to the pen pressure. . In the following description, the case where the writing pressure detection element 12a is a piezoelectric element will be described as an example.

The writing pressure detection unit 12(1) shown in FIG. 2A is an example in which two coil springs 12b1 and 12c1 are used as the two elastic members. As shown in FIG. 2A, the first coil spring 12b1 has a smaller diameter than the second coil spring 12c1. Moreover, the first coil spring 12b1 has a long total length when no force is applied to the second coil spring 12c1. By arranging the first coil spring 12b1 inside the second coil spring 12c1, the first coil spring 12b1 and the second coil spring 12c1 are arranged in parallel.

In the case of the writing pressure detection unit 12(1) shown in FIG. 2(A), when writing pressure is applied to the core 11, first, the writing pressure detection element 12a is pressed via the first coil spring 12b1. Pen pressure is applied. After that, the writing pressure on the core body 11 gradually increased, the entire length of the first coil spring 12b1 contracted until it became shorter than the overall length of the second coil spring 12c1, and the writing pressure further increased gradually. do. In this case, the pressing member 12x pressed by the core 11 also presses the second coil spring 12c1.

That is, the first coil spring 12b1 acts on the writing pressure detection element 12a until the writing pressure applied to the core 11 reaches a predetermined value, and the writing pressure is applied to the writing pressure detection element 12a. After that, when the writing pressure increases and reaches or exceeds a predetermined value, the first coil spring 12b1 acts on the writing pressure detection element 12a, and the second coil spring 12c1 acts on the pressing member 12x. In this case, the writing pressure applied to the writing pressure detection element 12a is reduced by the second coil spring 12c1. In this way, in addition to the first coil spring 12b1, the second coil spring 12c1 also acts in parallel. A pen pressure is applied to it.

The writing pressure detection unit 12(2) shown in FIG. 2(B) is an example in which a first elastic member 12b2 and a second elastic member 12c2 formed in a columnar shape are used as the two elastic members. . As shown in FIG. 2B, the first elastic member 12b2 has a long overall length when no force is applied to the second elastic member 12c2. In other respects, such as the shape and size of both end faces, the first elastic member 12b2 and the second elastic member 12c2 are the same. Then, as shown in FIG. 2B, by arranging the first elastic member 12b2 and the second elastic member 12c2 side by side, the first elastic member 12b2 and the second elastic member 12c2 are arranged in parallel. It is configured to be placed in

In the case of the writing pressure detection unit 12(2) shown in FIG. 2B, when the writing pressure is applied to the core 11, the writing pressure detection element 12a is first pushed through the first elastic member 12b2. pen pressure is applied. After that, the writing pressure on the core 11 gradually increases, and the first elastic member 12b2 shrinks until it becomes shorter than the second elastic member 12c2, and the writing pressure gradually increases. Suppose In this case, the pressing member 12x pressed by the core 11 also presses the second elastic member 12c2.

That is, until the writing pressure applied to the core 11 reaches a predetermined value, the first elastic member 12b2 acts on the writing pressure detecting element 12a to apply writing pressure to the writing pressure detecting element 12a. After that, when the pen pressure increases and reaches or exceeds a predetermined value, the first elastic member 12b2 acts on the pen pressure detecting element 12a, and the second elastic member 12c2 acts on the pressing member 12x. In this case, the writing pressure applied to the writing pressure detection element 12a is reduced by the second elastic member 12c2. Thus, in addition to the first elastic member 12b2, the second elastic member 12c2 also acts, and the writing pressure detection element is detected through both the first elastic member 12b2 and the second elastic member 12c2. Writing pressure is applied to 12a.

The writing pressure detection unit 12(3) shown in FIG. 2(C) uses, as two elastic members, a first elastic member 12b3 formed in a columnar shape and a second elastic member 12c3 formed in a cylindrical shape. is an example of As shown in FIG. 2C, the first elastic member 12b3 has a long overall length when no force is applied to the second elastic member 12c3. As shown by cutting the second elastic member 12c3 in two in the axial direction and removing the front part, the central part is hollow, and the first elastic member 12b3 is inserted into the hollow part. placed. As a result, the first elastic member 12b3 and the second elastic member 12c3 are arranged in parallel.

In the case of the writing pressure detection unit 12(3) shown in FIG. 2(C), when writing pressure is applied to the core 11, the writing pressure detection element 12a is first pushed through the first elastic member 12b3. pen pressure is applied. After that, the writing pressure on the core 11 gradually increases, and the entire length of the first elastic member 12b3 contracts until it becomes shorter than the overall length of the second elastic member 12c3, and the writing pressure gradually increases. Suppose In this case, the pressing member 12x pressed by the core 11 also presses the second elastic member 12c3.

That is, until the writing pressure applied to the core 11 reaches a predetermined value, the first elastic member 12b3 acts on the writing pressure detecting element 12a to apply writing pressure to the writing pressure detecting element 12a. After that, when the pen pressure increases and reaches or exceeds a predetermined value, the first elastic member 12b3 acts on the pen pressure detecting element 12a, and the second elastic member 12c3 acts on the pressing member 12x. In this case, the writing pressure applied to the writing pressure detection element 12a is reduced by the second elastic member 12c3. Thus, in addition to the first elastic member 12b3, the second elastic member 12c3 also acts, and the writing pressure detection element is detected through both the first elastic member 12b3 and the second elastic member 12c3. Writing pressure is applied to 12a.

In the configuration example shown in FIG. 2, the first elastic members 12b2 and 12b3 and the second elastic member 12c2 may be cylinders or polygonal cylinders. Also, the second elastic member 12c3 may be a cylinder or a rectangular tube. Also, the lengths and widths of the bottom surfaces of the first and second coil springs 12b1 and 12c1, the first elastic members 12b2 and 12b3, and the second elastic members 12c2 and 12c3 can be appropriately adjusted. Further, in the case of the writing pressure detection unit 12(2) shown in FIG. 2B, the first elastic member 12b2 and the second elastic member 12c2 may be arranged side by side without being in contact with each other.

In addition to the example shown in FIG. 2, for example, in the writing pressure detection unit 12(1) shown in FIG. can also be used. Further, in the writing pressure detection unit 12(2) shown in FIG. 2B, a plurality of second elastic members 12c2 may be arranged around the first elastic member 12b2. In short, the writing pressure detection unit 12 uses, for example, two or more elastic members, or includes one elastic member composed of two or more parts, to gradually apply writing pressure to the writing pressure detection element 12a. It can be of various constructions that allow it to be hung on a target.

[Deviation characteristics of writing pressure detection unit 12]
Next, as described with reference to FIG. 2, the bias characteristic of the writing pressure detection unit 12 configured using two elastic members will be described. Here, in order to simplify the description, the case of the writing pressure detection unit 12(1) having the configuration shown in FIG. 2A will be described as an example. In the case of the configuration example shown in FIG. 2A, the case where the elastic modulus (elastic modulus) of the first coil spring 12b1 is smaller than that of the second coil spring 12c1 will be considered as an example. That is, the first coil spring 12b1 is soft and deforms with a relatively small force, and the second coil spring 12c1 is hard and does not deform unless a larger force is applied.

FIG. 3 is a diagram for explaining the deviation characteristics of each component constituting the writing pressure detection unit 12(1) shown in FIG. 2A and the deviation characteristics of the writing pressure detection unit 12(1) as a whole. , the horizontal axis is the applied load (N), and the vertical axis is the displacement amount (mm). In FIG. 3A, characteristic Db is an example of the bias characteristic of the first coil spring 12b1, characteristic Dc is an example of the bias characteristic of the second coil spring 12c1, and characteristic Da is the bias characteristic of the writing pressure detection element 12a. Examples of each are shown.

In this specification, the term "biased" means that the shape is biased, that is, deformed. More specifically, the "bias" in the case where the elastic member is a coil spring or the like is that it contracts when a force is applied, and returns to its original shape when the applied force is released (the contracted spring expands). means In addition, when the elastic member is made of rubber or the like, the "bias" is such that the thickness becomes thinner (collapses) when force is applied, and the thickness returns (thinner) when the applied force is released. thickness returns to the original). In addition, when the elastic member has an elastic dish-like or plate-like shape, it dents (or warps) when a force is applied, and returns to its original state (dents) when the applied force is released. It means that something that has been warped or warped will return to its original state).

As described above, the elastic modulus k1 of the first coil spring 12b1 is smaller than the elastic modulus k2 of the second coil spring 12c1. That is, there is a relationship of "k1<k2". First, consider a case where a load (pressure) is applied to each of the writing pressure detection element 12a, the first coil spring 12b1, and the second coil spring 12c1. First, when a load (pressure) is applied to the first coil spring 12b1, as shown in characteristic Db of FIG. When multiplied, the amount of bias decreases and becomes smoother.

Conversely, the elastic modulus k2 of the second coil spring 12c1 is greater than the elastic modulus k1 of the first coil spring 12b1. Therefore, when a load is applied to the second coil spring 12c1, as shown in characteristic Dc in FIG. . Also in the case of the second coil spring 12c1, when a load of a predetermined value or more is applied, the amount of bias decreases, and the bias is gentle.

The writing pressure detection element 12a is a piezoelectric element, and when writing pressure is applied, it is distorted, but the amount of deviation is very small as indicated by the characteristic Da in FIG. 3(A). Each of the writing pressure detection element 12a, the first elastic member 12b, and the second elastic member 12c has the bias characteristic shown in FIG. 3(A). Since the amount of deflection of the writing pressure detection element 12a is very small, the overall deflection characteristics of the writing pressure detection section 12(1) formed by the first coil spring 12b1 and the second coil spring 12c1 arranged in parallel are is made to have a desired characteristic as indicated by characteristic D in FIG. 3(B).

That is, as described with reference to FIG. 2A, the total length of the first coil spring 12b1 is longer than the total length of the second coil spring 12c1, and the first coil spring 12b1 is arranged inside the second coil spring 12c1. there is For this reason, the deviation characteristic D of the writing pressure detection unit 12(1) as a whole in FIG. 3B is such that the elastic coefficient is The biasing characteristic of the small first coil spring 12b1 becomes dominant and biases.

After that, when the load (writing pressure) applied to the writing pressure detection unit 12(1) increases to some extent, the first coil spring 12b1 and the second coil spring 12c1 act in parallel as described above. Become. In this case, as shown in FIG. 3(B), the overall biasing amount of the writing pressure detection unit 12(1) is a curve obtained by adding the biasing characteristic of the first coil spring 12b1 to the biasing characteristic of the second elastic member 12c. It will change gently like drawing.

The deviation characteristic D of the writing pressure detection section 12(1) shown in FIG. 3B indicates the state of deviation (deformation) of the writing pressure detection section 12 as a whole according to the writing pressure. That is, when a load (writing pressure) is gradually applied to the writing pressure detection unit 12, the writing pressure detection unit 12(1) as a whole deviates as shown in characteristic D in FIG. do. Since the load (N)=elastic coefficient k×amount of deviation (amount of displacement) L (that is, load=kL), the deviation (deformation) is proportional to the load applied to the writing pressure detection element 12a. Therefore, the bias characteristic shown in FIG. 3B can be considered as the load characteristic applied to the writing pressure detection unit 12(1). Therefore, a pressure corresponding to the load (pen pressure) applied to the pen pressure detection unit 12(1) is applied to the pen pressure detection element 12a.

Therefore, the writing pressure detection element 12a of the writing pressure detection unit 12(1) having the deviation characteristic shown in FIG. Outputs a voltage corresponding to (pen pressure). That is, as shown by the non-linear bias characteristic D shown in FIG. 3B, the sensitivity is sufficiently high at the beginning of writing, and the detection sensitivity is smoothed according to the writing pressure applied during writing. Thus, the electronic pen 1 of this embodiment can have an output characteristic (writing pressure detection characteristic) that achieves the feel of writing characters on paper with a pencil.

The same applies to the pen pressure detection unit 12(2) shown in FIG. 2(B) and the pen pressure detection unit 12(3) shown in FIG. 2(C). The output characteristic (pen pressure detection characteristic) of the pen pressure detection element 12a, which is a piezoelectric element, generally exhibits a sharp linear change as described above. It is impossible to realize the same writing feeling with an electronic pen. Therefore, as described with reference to FIG. 2, pen pressure detection units 12(1), 12(2), and 12( 3). As a result, the writing pressure can be applied to the writing pressure detection element 12a so as to obtain the target output characteristics.

[Specific Configuration Example of Electronic Pen 1]
Next, as described with reference to FIG. 2, two elastic members are provided so that writing pressure can be applied to the writing pressure detection element 12a in accordance with the deviation characteristics shown in FIG. 3(B). A more specific configuration of the electronic pen will be described. The writing pressure detection element 12a, which is a piezoelectric element, generally has a characteristic that it does not output a voltage corresponding to the applied pressure unless a certain amount of pressure (for example, a pressure of about 3 g) is applied. That is, the writing pressure detection element 12a requires an on-load of about 3 g, for example. Therefore, the electronic pen 1 of this embodiment has a configuration in consideration of the on-load of the pen pressure detecting element 12a.

FIG. 4 is a diagram for explaining a specific configuration example of the electronic pen 1 of this embodiment. FIG. 4A shows the pen tip side of the electronic pen 1, which is obtained by cutting the casing 15 of the electronic pen 1 into two in the axial direction and removing the front part so that the inside can be viewed. FIG. 4 is a diagram showing; In FIG. 4A, the writing pressure detection unit 12 is shown as a cross-sectional view cut in the axial direction at the central portion thereof, as indicated by oblique lines. FIG. 4B is a diagram for explaining the pressure applied to the writing pressure detection element 12a.

As shown in FIG. 4A, inside a housing 15 having a cylindrical shape with a tapered pen tip, a portion of the tip 11a is protruded toward the tapered end side. , the core 11 is arranged. The core body 11 is composed of a tip portion 11a, an axial center portion 11b, and a bearing portion 11c. At the rear end side of the core body 11, a writing pressure detection module is arranged so as to be in contact with the core body 11. The writing pressure detection module is configured by sandwiching a writing pressure detection element 12a, which is a piezoelectric element, between a case 12Cs and a base 12Bs.

The case 12Cs has a bottom surface on the core body 11 side and a cylindrical shape with an opening on the opposite side. The base 12Bs is columnar and has a size that can be accommodated in the case 12Cs. The case 12Cs and the base 12Bs are formed using a non-conductive material with high hardness.

In addition, in the electronic pen 1 of this embodiment, the bearing portion 11c of the core 11 is in contact with the outer bottom surface of the case 12Cs. In this embodiment, the bearing portion 11c of the core 11 is fixed to the outer bottom surface of the case 12Cs by various methods such as welding, fusing, and adhesion. A portion consisting of the tip portion 11a and the axial center portion 11b of the core 11 is detachable from the tip side of the housing 15 with respect to the bearing portion 11c fixed to the case 12Cs. In other words, the portion consisting of the tip portion 11a and the axial portion 11b of the core body 11 is replaceable.

A first elastic member 12b is arranged on the rear end side of the base 12Bs of the writing pressure detection module so as to be in contact with the base 12Bs. The first elastic member 12b in this example is made of silicon rubber and formed in a hemispherical shape as shown in FIG. 4(A). Since the first elastic member 12b is thus formed in a hemispherical shape, the first elastic member 12b is largely biased at first by the writing pressure applied to the tip portion 11a of the core 11. , the amount of deviation is reduced when a writing pressure greater than or equal to a predetermined value is applied.

A second elastic member 12c is arranged on the rear end side of the first elastic member 12b so as to be in contact with part of the spherical surface of the first elastic member 12b. The second elastic member 12c is made of elastic resin or the like and is shaped like a dish having side walls. Also in the electronic pen 1 of this embodiment, when the writing pressure applied to the tip portion 11a of the core body 11 is small, the first elastic member 12b acts predominantly, and the first elastic member 12b acts against the writing pressure. A pen pressure is applied to the detection element 12a.

Suppose that a writing pressure equal to or greater than a predetermined value is applied to the tip portion 11a of the core body 11 . In this case, the first elastic member 12b further presses the bottom surface of the second elastic member 12c, and the end surface Cf of the side wall of the case 12Cs and the end surface Df of the side wall of the second elastic member 12c As a result, the end face Df of the side wall of the case 12Cs presses the end face Cf of the side wall of the second elastic member 12c .

That is, the first elastic member 12b acts on the writing pressure detecting element 12a to apply writing pressure to the writing pressure detecting element 12a until the writing pressure applied to the core 11 reaches a predetermined value. After that, when the pen pressure increases and reaches or exceeds a predetermined value, the first elastic member 12b acts on the pen pressure detecting element 12a and the second elastic member 12c acts on the case 12Cs. In this case, the writing pressure applied to the writing pressure detection element 12a is reduced by the second elastic member 12c.

In this manner, when a writing pressure equal to or greater than a predetermined value is applied to the tip portion 11a of the core 11, the first elastic member 12b and the second elastic member 12c act together. In this case, as can be seen from FIG. 4B, the first elastic member 12b and the second elastic member 12c are pressed through the case 12Cs, the pen pressure detecting element 12a and the base 12Bs. Furthermore, the end face Cf of the side wall of the case 12Cs and the end face Df of the side wall of the second elastic member 12c come into contact with each other, and the side wall of the second elastic member 12c is pressed by the side wall of the case 12Cs.

In such a state, the pen pressure detection package consisting of the case 12Cs, the pen pressure detection element 12a, and the base 12Bs presses the first elastic member 12b and the second elastic member 12c separately and simultaneously. becomes. That is, the first elastic member 12b and the second elastic member 12c act in parallel. In other words, the bottom surfaces of the first elastic member 12b and the second elastic member 12c are positioned in series. However, it also has a configuration in which the side wall of the case 12Cs presses the side wall of the second elastic member 12c. As a result, instead of always pressing the second elastic member 12c via the first elastic member 12b, at the same time as pressing the first elastic member 12b, another portion of the writing pressure detection package is pressed to the second elastic member 12c. A structure for pressing the side wall of the elastic member 12c is also formed so that the first elastic member 12b and the second elastic member 12c can act in parallel.

Then, when the end face Df of the side wall of the case 12Cs presses the end face Cf of the side wall of the second elastic member 12c, the side wall of the second elastic member 12c is crushed, and the first elastic member 12b presses the second elastic member. The bottom surface of 12c is further pressed. Therefore, in FIG. 4A, as indicated by the dotted line on the rear end side of the second elastic member 12c, the second elastic member 12c is located on the rear end side of the electronic pen 1 (the side opposite to the pen tip). ) so as to be recessed. Thus, the electronic pen 1 of this embodiment has a configuration in which the first elastic member 12b and the second elastic member 12c act in parallel according to the writing pressure.

In this embodiment, the cylindrical case 12Cs and the dish-shaped second elastic member 12c have the same outer shape and outer size, and the side walls are configured to have a certain thickness. ing. Also, the second elastic member 12c may be flat (plate-shaped).

Also, the second elastic member 12 c is locked by a first stopper (locking member) SP<b>1 provided inside the housing 15 . As a result, even if the second elastic member 12c is recessed toward the rear end side, the core body 11 and the writing pressure detection unit 12 are prevented from moving toward the rear end relative to the first stopper SP1. ing. When the writing pressure applied to the tip portion 11a of the core 11 is released, the first elastic member 12b and the second elastic member 12c return to their original states, and the core 11 is moved toward the pen tip. It is designed to push back to.

Further, as shown in FIG. 4A, a second stopper (locking portion) SP2 is provided inside the housing 15 on the pen tip side. In addition, a pen point side end portion of the bearing portion 11c of the core body 11 is provided with a core body side stopper (locking portion) 11SP projecting outward. As shown in FIG. 4A, a coil spring 13 for applying an ON load is provided between the second stopper provided on the housing 15 and the core side stopper 11SP provided on the bearing portion 11c. placed. The coil spring 13 always urges the core 11 toward the pen pressure detecting section 12 .

As a result, the coil spring 13 and the core body 11 always apply a predetermined pressure to the writing pressure detecting element 12a. In this embodiment, it is assumed that the on-load of the writing pressure detection element 12a, which is a piezoelectric element, is 3 g, for example. That is, it is assumed that the writing pressure detection element 12a does not output a voltage corresponding to the applied pressure unless a pressure of 3 g or more is applied. In this case, the coil spring 13 may be urged toward the pen pressure detecting section 12 with a pressure of 3 g against the core 11 .

As a result, due to the function of the coil spring 13, a pressure of 3 g is always applied to the writing pressure detecting element 12a, so that even if a slight writing pressure is applied to the tip portion 11a of the core 11, the writing pressure detecting element 12a , generates and outputs a voltage corresponding to the slightly applied writing pressure. As a result, writing information (drawing information) can be input to the tablet information terminal 2 through the position detection device 200 in such a manner that when the pencil slightly touches the paper, it leaves a thin layer of graphite. That is, the coil spring 13 is an on-load applying spring, in other words, an offset elastic member.

The voltage generated by the writing pressure detection element 12a in response to the writing pressure applied to the tip portion 11a of the core 11 is, for example, from the base 12Bs through the first conductive line L1 as shown in FIG. It is supplied to the writing pressure value calculation circuit 14 a of the circuit board 14 mounted on the housing 15 . The pen pressure value calculation circuit 14a calculates the pen pressure value based on the voltage value from the pen pressure detection element 12a, and supplies it to the oscillation circuit 14b. The oscillator circuit 14b responds to the writing pressure value, generates a signal for indicating a position (position indication signal), and supplies this to the core 11 through the second conductive line L2. The core 11 is made of a conductive material, and the position indication signal is sent from the tip portion 11 a of the core 11 toward the position detection device 200 .

In the electronic pen 1 of this embodiment having such a configuration, the pressure acting on the writing pressure detection element 12a will be summarized with reference to FIG. 4(B). First, even when no writing pressure WP is applied to the tip portion 11a of the core 11 (when not in use), the function of the coil spring 13 causes the writing pressure detection element 12a to detect As indicated by the arrow f1, an on-load f1 is applied at all times. As a result, even when a slight writing pressure is applied to the tip portion 11a of the core 11, the writing pressure detection element 12a can generate and output a voltage corresponding to the slight writing pressure.

Then, as shown in FIG. 4B, the stroke, which is the amount of movement of the core body 11 from the state where the tip portion 11a of the core body 11 of the electronic pen 1 of this embodiment is not pressed to the state where the core body 11 is pushed down, is, for example, Assume that it is 0.3 mm. In this case, when writing pressure is applied to the tip portion 11a of the core 11, as shown in FIG. Member 12b acts predominantly. As a result, the writing pressure is sufficiently transmitted to the writing pressure detection element 12a, but the writing pressure is somewhat restricted so that a sudden large writing pressure is not transmitted to the writing pressure detection element 12a.

After that, when further writing pressure is applied to the tip portion 11a of the core 11, as shown in FIG. A second elastic member 12c acts in parallel with 12b. As a result, the writing pressure transmitted to the writing pressure detection element 12a is moderately regulated. As a result, the writing pressure detection characteristics of the writing pressure detection unit 12 can be made similar to the writing pressure applied to a pencil when writing characters or pictures on paper with a pencil.

FIG. 5 shows the output characteristics (writing pressure detection characteristics) of the writing pressure detection element 12a (FIG. 5A), the writing pressure detection element 12a, the first elastic member 12b, and the second elastic member 12c. FIG. 5B is a diagram showing output characteristics (pen pressure detection characteristics) of the pen pressure detection unit 12 shown in FIG. 4A. As shown in FIG. 5A, the writing pressure detection element 12a, which is a piezoelectric element, does not output a voltage corresponding to the pressure unless a predetermined pressure (eg, 3 g) or more is applied. Then, when a pressure equal to or higher than a predetermined pressure is applied, the output voltage exhibits a sharp linear change. In other words, the writing pressure detection element 12a has a characteristic of generating and outputting a large voltage even with a very slight pressure.

However, in the case of the electronic pen 1 of this embodiment, the on-load coil spring 13 is provided, and the writing pressure detecting element 12a, the first elastic member 12b, and the second elastic member 12c detect the writing pressure. 12 are configured. Therefore, as shown in FIG. 5B, the writing pressure detection characteristic of the writing pressure detection element 12a mounted on the electronic pen 1 of this embodiment is sufficiently sensitive at the beginning of writing and can realize the target pen pressure detection characteristic that the detection sensitivity changes smoothly according to the applied pen pressure.

In other words, in the writing pressure detection unit 12 of the electronic pen 1 shown in FIG. 4A, the first elastic member 12b and the second elastic member 12c act in parallel on the writing pressure detection element 12a. have a configuration. Therefore, the overall displacement characteristic of the writing pressure detection unit 12 is similar to that shown in FIG. 3(B). As described above, since the amount of deviation is proportional to the load applied to the writing pressure detection element, the output characteristics (writing pressure detection characteristics) of the writing pressure detection unit 12 are shown in FIG. Thus, it corresponds to the deviation characteristic of FIG. 3(B).

[Summary of configuration example of electrostatic coupling type electronic pen 1]
FIG. 6 is a block diagram for explaining a schematic configuration of the electronic pen 1 of this embodiment. In FIG. 6, the same parts as those shown in FIG. 5 are given the same reference numerals. As shown in FIG. 6, the core body 11 is configured such that the writing pressure detection section 12 can be pressed according to the writing pressure. As described above, the writing pressure detection unit 12 is a portion configured to include the writing pressure detection package including the writing pressure detection element 12a, the first elastic member 12b, and the second elastic member 12c. .

A voltage generated in the writing pressure detection unit 12 according to the applied writing pressure is supplied to the writing pressure value calculation circuit 14a. The pen pressure value calculation circuit 14a calculates a pen pressure value according to the output voltage from the pen pressure detection unit 12, and supplies it to the oscillation circuit 14b. The oscillation circuit 14b forms a position indication signal whose frequency is changed according to the writing pressure value, supplies this to the core body 11, and transmits it from the core body 11 toward the position detection device 200. there is

Although not shown in FIG. 4, a power supply circuit 14c is provided on or near the circuit board 14 to supply power to required portions such as the writing pressure value calculation circuit 14a and the oscillation circuit 14b. is now possible. The power supply circuit 14c has, for example, a battery, and has a configuration in which power is supplied from this battery to each part.

Alternatively, the power supply circuit 14c may be configured to include a charging coil, an electric double layer capacitor, a rectifying diode, and a voltage conversion circuit. In this case, the power supply circuit receives a magnetic field from the outside to generate a current, stores it in an electric double layer capacitor, and forms a drive power supply from this through a rectifier diode and a voltage conversion circuit. will be supplied to

As described above, the capacitive coupling type electronic pen 1 of this embodiment can indicate the position to the position detection device 200 by transmitting the oscillation signal from the oscillation circuit 14b through the core 11. In addition, it is possible to notify the writing pressure.

[Configuration example of electrostatic coupling type position detection device 200]
FIG. 7 illustrates a configuration example of a position detection device 200 that receives a signal from the electronic pen 1 of this embodiment, detects an indicated position on the sensor, and detects writing pressure applied to the electronic pen 1. It is a block diagram for doing. The tablet information terminal 2 is equipped with an electrostatic coupling type position detection device 200 shown in FIG.

The capacitive coupling type position detection device 200 of this embodiment comprises a sensor 210 and a pen detection circuit 220 connected to the sensor 210, as shown in FIG. The sensor 210 is formed by laminating a first conductor group 211 and a second conductor group 212 . The first conductor group 211 is, for example, a plurality of first conductors 211Y ₁ to 211Y _m extending in the lateral direction (X-axis direction) arranged parallel to each other with a predetermined interval in the Y-axis direction. . In addition, the second conductor group 212 includes a plurality of second conductors 212X ₁ to 212X _n extending in a direction intersecting the first conductors, in this example, a vertical direction (Y-axis direction) perpendicular to the first conductors. They are arranged in parallel in the X-axis direction with a predetermined interval. In this way, the sensor 210 of the position detection device 200 uses the sensor pattern formed by intersecting the first conductor group 211 and the second conductor group 212 to detect the position indicated by the electrostatic electronic pen 1. It has a configuration to detect.

The pen detection circuit 220 includes a selection circuit 221 serving as an input/output interface with the sensor 210, an amplifier circuit 222, a bandpass filter 223, a detection circuit 224, a sample hold circuit 225, and AD (Analog to Digital) conversion. It consists of a circuit 226 and a control circuit 227 .

Selection circuit 221 selects one conductor 211 Y or 212 X from first conductor group 211 and second conductor group 212 based on a control signal from control circuit 227 . A conductor selected by the selection circuit 221 is connected to an amplifier circuit 222 , and a signal from the capacitively coupled electronic pen 1 is detected by the selected conductor and amplified by the amplifier circuit 222 . The output of this amplifier circuit 222 is supplied to a band-pass filter 223 to extract only the frequency component of the signal transmitted from the electronic pen 1 of the capacitive coupling type.

The output signal of the bandpass filter 223 is detected by the detection circuit 224 . The output signal of the detection circuit 224 is supplied to the sample hold circuit 225, sampled and held at a predetermined timing by the sampling signal from the control circuit 227, and then converted into a digital value by the AD conversion circuit 226. Digital data from the AD conversion circuit 226 is read and processed by the control circuit 227 .

The control circuit 227 operates to send control signals to the sample-and-hold circuit 225, the AD conversion circuit 226, and the selection circuit 221 according to a program stored in an internal ROM. Then, the control circuit 227 calculates the coordinates of the position on the sensor 210 indicated by the electronic pen 1 of the capacitive coupling type from the digital data from the AD conversion circuit 226, and the pen pressure detection unit 12 of the electronic pen 1 Detect the detected pen pressure. Thus, the electronic pen 1 and the position detection device 200 of this embodiment constitute a position detection system. The position detection system in this case can detect the indicated position and the writing pressure based on the signal from the electronic pen 1 having the writing pressure detection characteristics shown in FIG. 5(B).

[Effects of Embodiment]
The electronic pen 1 of the embodiment described above uses the writing pressure detection element 12a, which is a piezoelectric element. As described with reference to FIG. 5A, the pen pressure detection element 12a requires an on-load and has a pen pressure detection characteristic (output voltage characteristic) that undergoes a sharp linear change. However, by applying an on-load by the function of the coil spring 13, the on-load of the electronic pen 1 itself can be reduced to 0 g. The writing pressure detection unit 12 has a structure in which the first elastic member 12b and the second elastic member 12c act in parallel on the writing pressure detection element 12a. Therefore, as shown in FIG. 5B, the writing pressure detection characteristic of the writing pressure detection unit 12 is sufficiently sensitive at the beginning of writing, and the detection sensitivity gradually increases according to the writing pressure applied during writing. can be the desired property of changing to

As a result, by using the electronic pen 1 and the position detection device 200, it is possible to achieve a writing feel similar to that of writing letters or pictures on paper with a pencil. In other words, by using the electronic pen 1, characters and pictures can be input to the tablet information terminal 2 of this embodiment as if they were written on paper. Therefore, when writing characters or pictures on the display screen 2D of the tablet-type information terminal 2 using the electronic pen 1, the same writing feeling as when writing characters or pictures on paper with a pencil is reproduced. be able to. As a result, the electronic pen 1 and the tablet-type information terminal 2 can be used to express characters and pictures on paper with a pencil.

[Modification]
In the above-described embodiment, the first elastic member 12b is made of silicon rubber and has a hemispherical shape, but the shape is not limited to this. The first elastic member 12b may be made of various industrial materials having rubber elasticity called elastomer or the like, or synthetic resin or natural material having elasticity may be used. Also, the shape may be conical, pyramidal, or the like, and in this case, the apex may be rounded. Of course, the shape of the first elastic member 12b can be various shapes such as a prismatic shape and a cylindrical shape, as long as desired characteristics can be obtained. Alternatively, a coil spring, a plate spring, or the like may be used as the first elastic member 12b.

Further, in the above-described embodiment, the second elastic member 12c is made of resin and has a dish shape, but the present invention is not limited to this. As with the first elastic member 12b, the second elastic member 12c may be made of various industrial materials having rubber elasticity called elastomer, or may be made of a natural material having elasticity. . Also, the shape can be adjusted so that the height of the side wall is adjusted appropriately. Alternatively, a coil spring, a plate spring, or the like may be used as the second elastic member 12c.

As described above, the first elastic member 12b and the second elastic member 12c can be used in various ways as long as desired characteristics such as those shown in FIG. Various shapes can be used depending on the material. Therefore, the first elastic member 12b and the second elastic member 12c may be integrally formed of the same material or different materials.

Further, in the above-described embodiment, one coil spring 13 is used for applying on-load, but the present invention is not limited to this. A plurality of coil springs may be arranged around the core body 11, or a leaf spring may be used instead of the coil spring.

Further, in the above-described embodiment, the core has been described as being composed of a portion consisting of the tip portion 11a and the axial center portion 11b, and a portion consisting of the bearing portion 11c, but it is not limited to this. do not have. The core body 11 may be one in which the tip portion 11a, the axial center portion 11b, and the bearing portion 11c are integrally formed. In this case, for example, when the tip portion 11a is worn, the entire core body 11 may be configured to be replaceable.

Further, the shape of the core body 11 is not limited to that of the embodiment described above, and the shape of the core body 11 can be various shapes as long as the same function can be realized. In particular, the tip portion 11a and the shaft-side stopper 11SP of the bearing portion 11c can have various shapes.

Also, the output characteristics (writing pressure detection characteristics) of the writing pressure detection unit 12 shown in FIG. It is also possible to make it gentle. In this case, the elastic member connected in series with the pen pressure detecting element 12a should have an elastic modulus that provides desired characteristics. The modulus of elasticity can be changed not only by the material but also by the shape.

Also, instead of setting the output characteristics (writing pressure detection characteristics) of the writing pressure detection unit 12 to predetermined ones, a lower limit characteristic (lower limit curve) and an upper limit characteristic (upper limit curve) may be provided. Then, the characteristics of the first elastic member 12b, the second elastic member 12c, and the coil spring 13 are determined so that the output characteristics of the writing pressure detection unit 12 are between the lower limit characteristics and the upper limit characteristics, and The first elastic member 12b, the second elastic member 12c, and the coil spring 13 may be constructed so as to match.

Further, in the above-described embodiment, two elastic members, ie, the first elastic members 12b, 12b1, 12b2, 12b3 and the second elastic members 12c, 12c1, 12c2, 12c3 are used. is not limited to By using three or more elastic members in parallel, it is possible to change the writing pressure detection characteristic step by step.

Also, instead of two or more elastic members, one elastic member comprising two or more portions may be used. FIG. 8 is a diagram for explaining a configuration example of a writing pressure detection unit configured using one elastic member composed of two parts. In FIG. 8, the portion constituting the writing pressure detection unit is shown as a cross-sectional view when cut in the axial direction, as indicated by oblique lines. FIG. 8A shows an example in which a writing pressure detection unit is composed of a pressing member 21 pressed by the core body 11, a writing pressure detecting element 12a, and an elastic member 22. FIG. In FIG. 8A, the elastic member 22 is, for example, a cylinder having the same central axis and a long diameter cylinder portion located on the rear end side (opposite side to the core body 11) and this diameter A long cylindrical portion and a short-diameter cylindrical portion protruding toward the core 11 are integrally formed.

Since the elastic member 22 has such a structure in which two parts are integrally formed, in the case of the writing pressure detecting portion shown in FIG. Then, first, the short-diameter cylindrical portion of the elastic member 22 acts mainly to transmit the writing pressure to the writing pressure detecting element 12a. Then, when a writing pressure above a certain level is applied, the pressing member 21 also presses the cylindrical portion having a long diameter. As a result, the two portions, the cylindrical portion with the short diameter and the cylindrical portion with the long diameter having the same central axis, act in parallel on the pen pressure detecting element 12a, thereby detecting the pen pressure as shown in FIG. 8(A). The characteristic can be the pen pressure detection characteristic shown in FIG. 5B.

However, in the case of the configuration shown in FIG. 8A, depending on the elastic modulus of the elastic member 22, the pen pressure detecting element 12a and the cylindrical portion with a short diameter are pressed so as to fit into the cylindrical portion with a long diameter. can be difficult to do. Therefore, as shown in the elastic member 23 of FIG. 8B, an elastic member having side walls is used. That is, as shown in FIG. 8(B), in addition to the short-diameter cylindrical portion and the long-diameter cylindrical portion having the same central axis, along the outer periphery of the long-diameter cylindrical portion located on the rear end side A side wall projecting to the core body 11 side is provided. In this case, the short-diameter cylindrical portion having the same central axis extends toward the core body 11 from the side wall.

By using the elastic member 23 shown in FIG. 8(B), when writing pressure is applied to the tip of the core 11, first, the short-diameter cylindrical portion of the elastic member 23 acts mainly to apply the writing pressure. It is transmitted to the writing pressure detection element 12a. Then, when a writing pressure above a certain level is applied, the pressing member 21 also presses the side wall provided along the outer periphery of the cylindrical portion having the long diameter. As a result, the short-diameter cylindrical portion having the same central axis and the side wall protruding toward the core 11 along the outer circumference of the long-diameter cylindrical portion act in parallel on the pen pressure detecting element 12a. , the writing pressure detection characteristics shown in FIG. 5B can be realized.

Further, as shown in FIG. 8(C), the pressing member 24 is provided with side walls along the outer periphery without changing the configuration of the elastic member 22 shown in FIG. 8(A). In the case of the writing pressure detection unit shown in FIG. 8C, when writing pressure is applied to the tip of the core body 11, first, the cylindrical portion with a short diameter acts mainly to detect the writing pressure. It is transmitted to the detection element 12a. Then, when a writing pressure above a certain level is applied, the side wall provided along the outer periphery of the pressing member 24 also presses the long-diameter cylindrical portion of the elastic member 22 . As a result, the two portions, the cylindrical portion with the short diameter and the cylindrical portion with the long diameter having the same central axis, act in parallel on the pen pressure detecting element 12a, thereby detecting the pen pressure shown in FIG. 5(B). characteristics can be realized.

Also, as shown in FIG. 8D, both the pressing member and the elastic member may have side walls. That is, the elastic member 25 shown in FIG. 8(D) includes a cylindrical portion with a short diameter and a cylindrical portion with a long diameter having the same central axis, and along the outer periphery of the cylindrical portion with a long diameter, the It has a side wall projecting to the side. In this case, the short-diameter cylindrical portion having the same central axis extends toward the core body 11 from the side wall.

Further, the pressing member 24 shown in FIG. 8(D) has a structure in which side walls are provided along the outer periphery thereof. In the case of the writing pressure detecting portion shown in FIG. 8D, when writing pressure is applied to the tip of the core 11, first, the short-diameter cylindrical portion of the elastic member 25 acts mainly to The pressure is transmitted to the writing pressure detection element 12a. Then, when writing pressure above a certain level is applied, the side wall of the pressing member 24 also presses the side wall of the elastic member 25 . As a result, the two portions of the short-diameter cylindrical portion having the same central axis and the side wall provided along the outer circumference of the long-diameter cylindrical portion act in parallel on the pen pressure detecting element 12a, thereby The writing pressure detection characteristics shown in (B) can be realized.

Further, as described with reference to FIG. 8, the present invention is not limited to the one using one elastic member consisting of two parts. A detection unit can also be configured. For example, when length α<length β<length θ, a cylindrical portion with a diameter α having the same central axis, a cylindrical portion with a diameter β, and a cylindrical portion with a diameter θ are integrally formed in order. An elastic member can also be used. Also, the thickness of the side walls provided on the elastic members 23 and 25 may be changed stepwise.

Further, the writing pressure detection unit may be configured by combining one elastic member composed of two parts and another elastic member. In this way, by using a plurality of elastic members, by using an elastic member composed of a plurality of parts, and by adjusting the shape, material, elastic modulus, etc. of the elastic member and the pressing member, the writing pressure detection characteristics can be improved step by step. is an important feature of the electronic pen of the present invention.

DESCRIPTION OF SYMBOLS 1... Electronic pen 11... Core body 11a... Tip part 11b... Axial part 11c... Bearing part 11SP... Core side stopper 12... Writing pressure detection part 12a... Writing pressure detection element 12b... First Elastic member 12c Second elastic member 12Cs Case 12Bs Base 13 Coil spring (for applying on-load) 14 Circuit board 14a Writing pressure value calculation circuit 14b Oscillation circuit 14c Power supply circuit 15 Housing 2 Tablet information terminal 200 Position detection device 210 Sensor 211 First conductor group 211Y ₁ to 211Y _m First conductor 212 Second conductor Group 212X ₁ to 212X _n second conductor 220 pen detection circuit 221 selection circuit 222 amplifier circuit 223 bandpass filter 224 detection circuit 225 sample hold circuit 226 AD ( Analog to Digital) conversion circuit, 227 ... control circuit

Claims (13)

The tip protrudes from the end of a pen-shaped housing provided with a housing-side locking portion inside, and is movable in the axial direction according to the writing pressure applied to the tip. a core body provided with a core body-side engaging portion;
a writing pressure detection unit disposed in the housing and pressed by the core;
an offset elastic member that biases the core toward the writing pressure detection unit by being sandwiched between the housing-side locking portion and the core-side locking portion;
The writing pressure detection unit is
A writing pressure detection element that outputs an electric signal according to the applied pressure, a first elastic member, and a second elastic member are provided in series in the axial direction,
The core body is positioned on the front end side of the writing pressure detection element in the axial direction, the first elastic member is positioned on the rear end side of the writing pressure detection element in the axial direction, and the first elastic member is positioned on the rear end side of the writing pressure detection element in the axial direction. The second elastic member is positioned on the rear end side of the elastic member in the axial direction,
When the writing pressure applied to the core body is less than a predetermined value, the first elastic member acts predominantly on the writing pressure detection element, and the writing pressure applied to the core body is reduced to a predetermined value. In the above case, the electronic pen is characterized in that the first elastic member and the second elastic member act on the writing pressure detection element . The electronic pen according to claim 1,
The writing pressure detection unit includes a pressing member that is pressed by the core body and presses the writing pressure detection element,
The pressing member has a side wall projecting toward the second elastic member, or the second elastic member has a side wall projecting toward the pressing member,
The pressing member presses the second elastic member when the writing pressure applied to the core body reaches or exceeds the predetermined value.
An electronic pen characterized by: The electronic pen according to claim 1,
The first elastic member and the second elastic member are separate bodies.
An electronic pen characterized by: The electronic pen according to claim 1,
The first elastic member and the second elastic member are constructed integrally.
An electronic pen characterized by: The electronic pen according to claim 1,
An electronic pen, wherein the writing pressure detection element is a piezoelectric element that generates a voltage corresponding to the applied pressure. The electronic pen according to claim 2,
The electronic pen according to claim 1, wherein the pressing member faces the second elastic member at a predetermined distance in a state where writing pressure is not applied to the core body. The electronic pen according to claim 1 ,
The first elastic member is formed in a hemispherical shape.
An electronic pen characterized by: The electronic pen according to claim 1 ,
The electronic pen, wherein the second elastic member has a plate-like or dish-like shape. The electronic pen according to claim 1 ,
The electronic pen, wherein the first elastic member is made of silicone rubber. The electronic pen according to claim 1 ,
The electronic pen , wherein the second elastic member is made of resin. The electronic pen according to claim 1,
An electronic pen, comprising: a pen pressure calculator that receives a detection output from the pen pressure detection element and calculates a pen pressure value. The electronic pen according to claim 1,
The electronic pen, wherein the offset elastic member is a coil spring. A position detection system comprising an electronic pen and a position detection device that detects a pointing position on an input screen pointed by the electronic pen and detects writing pressure applied to the tip of the electronic pen,
The electronic pen is
The tip protrudes from the end of a pen-shaped housing provided with a housing-side locking portion inside, and is movable in the axial direction according to the writing pressure applied to the tip. a core body provided with a core body-side engaging portion;
a writing pressure detection unit disposed in the housing and pressed by the core;
an offset elastic member that biases the core toward the writing pressure detection unit by being sandwiched between the housing-side locking portion and the core-side locking portion;
The writing pressure detection unit is
A writing pressure detection element that outputs an electric signal according to the applied pressure, a first elastic member, and a second elastic member are provided in series in the axial direction,
The core body is positioned on the front end side of the writing pressure detection element in the axial direction, the first elastic member is positioned on the rear end side of the writing pressure detection element in the axial direction, and the first elastic member is positioned on the rear end side of the writing pressure detection element in the axial direction. The second elastic member is positioned on the rear end side of the elastic member in the axial direction,
When the writing pressure applied to the core body is less than a predetermined value, the first elastic member acts predominantly on the writing pressure detection element, and the writing pressure applied to the core body is reduced to a predetermined value. In the above case, the first elastic member and the second elastic member act on the writing pressure detection element ,
The position detection device is
A signal sent from the electronic pen is received to detect a position indicated by the electronic pen on the input screen, and a pen pressure applied to the tip of the core body of the electronic pen is detected. A position detection system comprising a circuit unit.

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