JPH06129929A - Pressure detection capacitor and pressure detection coordinate indicator - Google Patents

Abstract

PURPOSE:To realize a pressure detection capacitor wherein its electrostatic capacity is changed largely by a pressure and to realize a pressure detection coordinate indicator, for an electromagnetic induction-type coordinate readout apparatus, wherein a resonance frequency is changed largely by a pressure. CONSTITUTION:A dielectric 6 is formed to be a convex lens shape, and it is sandwiched between a first pressure detection electrode 4 and a second pressure detection electrode 5. A pressure transmission member 2 presses the circumference of the second pressure detection electrode 5 when a pressure is exerted on a part protruding from a case 1. The first pressure detection electrode 4 and the second pressure detection electrode 5 are bent by following the curved surface of the dielectric 6 as the pressure is increased, and their contact area is increased. In this manner, the electrostatic capacity between the first pressure detection electrode 4 and the second pressure detection electrode 5 is changed by the pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitor of which electrostatic capacity changes according to pressure and a coordinate indicator of an electromagnetic induction type coordinate reading device for detecting an operating pressure by using the capacitor.

[0002]

2. Description of the Related Art A conventional pressure detecting capacitor and a pressure detecting coordinate indicator using the same are disclosed in JP-A-3-67318.
(Hereinafter referred to as the first conventional example), Japanese Patent Laid-Open No. 4-96212.
(Hereinafter referred to as a second conventional example) is disclosed.

FIG. 14 is a block diagram of a pressure detecting capacitor according to a first conventional example. In this pressure detecting capacitor, a dielectric 903 is sandwiched between an electrode 901 and an electrode 902, and an elastic body 904 and an elastic body 905 are arranged outside thereof. When pressure is applied to the elastic bodies 904 and 905, the electrostatic capacitance between the electrodes 901 and 902 changes according to the pressure.

FIG. 15 is a block diagram of a pressure detecting capacitor according to a second conventional example. In this pressure detecting capacitor, a first electrode 911 is sintered on a dielectric 913, a second electrode 912 is arranged with a ring-shaped spacer 916 sandwiched therebetween, and a pressing body 917 is further provided. By pressing the pressing body 917, the second electrode 912 bends and the dielectric 913
To the first electrode 9 due to a change in the contact area between the two.
The capacitance between 11 and the second electrode 912 is changed.

[0005]

However, in the pressure detecting capacitor according to the first conventional example, the contact state between the electrodes 901 and 902 and the dielectric 903 is not clearly set, so that the pressure and the capacitance are different from each other. Relationships are subject to accidental contact conditions. Ideal state, ie electrode 901,
In the state where 902 and the dielectric 903 are in complete contact, the capacitance does not change even if the pressure changes. Actually, there is a certain amount of space between the electrodes 901 and 902 and the dielectric 903, so that the capacitance changes when pressure is applied, but the amount of change is only minute.

In the pressure detecting capacitor according to the second conventional example, the contact state between the second electrode 912 and the dielectric 913 is determined by the thickness of the spacer 916 and the spring constant of the bending of the second electrode 912. However, the contact area that is dominant in the change in capacitance is only the amount due to the bending of the electrode inside the ring of the spacer 916. That is, the second electrode 9
Since the 12 and the dielectric 913 do not come into contact with each other over the entire surface, the amount of change in capacitance is only a minute amount. The second conventional example discloses that instead of providing the spacer 916, a protrusion having the same shape as the spacer 916 may be provided on the contact surface of the dielectric 913. Although it is doubtful that the protrusion can be formed in a ring shape with the dielectric 913 to realize the target pressure detecting capacitor of the second conventional example, however, even with such a configuration, the amount of change in capacitance can be changed. Is just a small thing as well.

On the other hand, as a coordinate reading device, there is one having the principle shown in the block diagram of FIG. In this coordinate reading device, the coordinate indicator 922 is provided with a resonance circuit 923, and the tablet 92 is constructed by laying the resonance circuit 923 with the sense lines 121 intersecting each other.
When placed on 0, a closed loop circuit including the amplifier 924 is configured by electromagnetic coupling between the sense line 921 and the resonance circuit 923, and the closed loop oscillation condition is satisfied to cause oscillation. Since the intensity of this oscillation has information on the distance between the crossing region of the sense lines 921 and the resonance circuit 923, if a plurality of sense lines 921 are laid and the oscillation intensity is observed while scanning, the coordinate indicator 922 can be obtained from the distribution state of the oscillation intensity. The position of can be calculated.

The frequency of the oscillation signal is the resonance circuit 923.
Since the resonance frequency is equal to the resonance frequency of, the pressure detection capacitor 935 whose capacitance changes according to the operation pressure is connected in parallel to the resonance circuit 933 as shown in FIG. 17, and the operation pressure is applied to the pressure detection capacitor 935 to cause resonance. If the frequency is configured to change, the operating state of the pressure detection capacitor 935 can be detected by detecting the oscillation frequency on the tablet side. At this time, if the resonance frequency can be greatly changed, it becomes very easy to detect the change.

In the conventional coordinate reading device, the change in the electrostatic capacitance was small as the pressure detecting capacitor, so the change in the oscillation frequency due to the operation was small. Therefore, in order to detect the change in the oscillation frequency, the change in the phase is actually detected, and a precise phase detection circuit for that purpose is required. In addition, it was necessary to strictly adjust the reference resonance frequency of the coordinate indicator when it was not operated. The detection error of the phase change and the deviation of the reference resonance frequency directly lead to the detection error of the operation state, which makes the pressure detection by this technique difficult.

Based on the above background, the present invention has been made to solve the problems of the conventional pressure detecting capacitor and pressure detecting coordinate indicator. The first purpose thereof is to realize a pressure detecting capacitor whose electrostatic capacitance continuously and largely changes with pressure.

A second object is to realize a pressure detecting capacitor in which the electrostatic capacitance is turned on / off in the state where the pressure is small, and the electrostatic capacitance continuously changes greatly as the pressure increases. A third object of the present invention is to provide a coordinate indicator used in an electromagnetic induction-type coordinate reading device and having a resonance circuit, which is capable of continuously and greatly changing the resonance frequency by operating pressure. Is.

A fourth object of the present invention is to provide a pressure detection coordinate indicator capable of discontinuously and greatly changing the resonance frequency in the state where the operating pressure is small, and further increasing the pressure to continuously and greatly change the resonance frequency. Is to be realized.

[0013]

In order to solve the above-mentioned problems, in the first structure of the present invention, a pair of pressure detecting electrodes,
The dielectric for which the contact surface with the electrode for pressure detection is formed in a concave or convex curved surface, and the pressure transmitting surface is formed in a convex or concave shape corresponding to the unevenness of the contact surface of the dielectric for pressure detection. A pressure detecting capacitor was constructed by providing pressure to the electrodes and providing a pressure transmitting member adapted to change the contact area between the pressure detecting electrode and the dielectric depending on the magnitude of the pressure.

In the second structure, a pair of pressure detecting electrodes, a dielectric having a concave or convex curved contact surface with the pressure detecting electrodes, and irregularities on the contact surface of the dielectric are dealt with. The pressure transmitting surface is formed in a convex shape or a concave shape, and the pressure is transmitted to the pressure detecting electrode, and the contact area between the pressure detecting electrode and the dielectric is changed according to the magnitude of the pressure. A pressure transmitting member, a pair of switch electrodes provided on a surface opposite to the pressure transmitting surface of the first pressure transmitting member, and one electrode of which is connected to one of the pressure detecting electrodes; A second pressure transmitting member for transmitting pressure to the member and a surface of the second pressure transmitting member facing the switch electrode, and contacting the switch electrode by receiving pressure to connect between the switch electrodes And a conductive member provided so that To constitute a pressure sensing capacitor.

In a coordinate indicator having a parallel resonance circuit including a coil and a capacitor, which is used in an electromagnetic induction type coordinate reader in the third configuration, the pressure detection capacitor according to the first configuration is connected in parallel with the parallel resonance circuit. A pressure detection coordinate indicator was constructed by providing an operation member that is connected to the pressure transmission member of the pressure detection capacitor and further connected to the pressure transmission member of the pressure detection capacitor.

Further, in a coordinate indicator having a parallel resonance circuit including a coil and a capacitor, which is used in the electromagnetic induction type coordinate reading apparatus in the fourth configuration, the pressure detecting capacitor according to the second configuration is parallel to the parallel resonance circuit. The pressure detecting coordinate indicator is provided with an operating member that is connected to the second pressure transmitting member of the pressure detecting capacitor.

[0017]

According to the pressure detecting capacitor of the first structure, when pressure is applied to the pressure transmitting member, the pressure transmitting surface pushes the pressure detecting electrode, and thus the pressure detecting electrode is formed on the curved surface of the dielectric. And the contact area with the flexible dielectric is increased. Therefore, the electrostatic capacitance between the pair of pressure detection electrodes changes greatly in the initial state from the state of partial contact to the state of full contact.

According to the pressure detecting capacitor of the second structure, when pressure is applied to the second pressure transmitting member, the conductive member facing the switch electrode first contacts the switch electrode, and the switch circuit is closed. . When pressure is further applied, the second pressure transmission member pushes the first pressure transmission member, and the pressure transmission surface pushes the pressure detection electrode. For this reason, the pressure detecting electrode bends following the contact surface formed on the curved surface of the dielectric to increase the contact area with the dielectric. For this reason, the electrostatic capacitance between the pair of pressure detection electrodes largely changes in the initial state from the state of partial contact to the state of full contact. As described above, in the second configuration, the switch circuit is first closed when the pressure is low, and the capacitance increases as the pressure increases, which is a two-step operation.

According to the pressure detection coordinate indicator of the third structure, the pressure transmission member of the pressure detection capacitor is pushed by pushing the operating member, and the capacitance continuously changes greatly by the pushing pressure. Therefore, the resonance frequency of the resonance circuit also changes continuously and greatly.

According to the pressure detection coordinate indicator of the fourth structure, the switch of the pressure detection capacitor is first closed by pushing the operating member, and the capacitance is greatly changed by further increasing the pressure. For this reason, the resonance frequency of the resonance circuit changes discontinuously when the pressure is small, and then changes largely continuously with the pressure.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a first embodiment relating to the pressure detecting capacitor of the present invention. Reference numeral 6 denotes a dielectric, which is a thin disk-shaped and has both end faces formed in a convex lens shape. The material of the dielectric 6 is arbitrarily selected depending on the required electrostatic capacity depending on the magnitude of the dielectric constant. The first pressure detection electrode 4 and the second pressure detection electrode 5 are thin metal discs made of a material having a spring property. These electrodes are arranged so as to sandwich the dielectric 6. The pressure transmission member 2 is for pushing around the second pressure detection electrode 5, and the pressure transmission surface in contact with the pressure detection electrode 5 is a portion whose center bends convexly when the pressure detection electrode 5 is pushed. It is processed into a concave shape to avoid.

These members are housed in the case 1 as shown in the figure. The portion of the case 1 in which the first pressure detection electrode 4 is housed is processed into a concave shape so as to avoid the portion where the first pressure detection electrode 4 bends, like the pressure transmission surface of the pressure transmission member 2. Each member is housed so as to be slidable in the direction in which pressure is applied, that is, in the horizontal direction in the figure. The pressure transmitting member 2 is configured to press the second pressure detecting electrode 5 against the dielectric 6 with a small pressure in advance by the spring 9.
Further, a part of the rear end of the pressure transmitting member 2 projects from the case 1 so that external pressure can be applied. A terminal 10 is connected to the first pressure detection electrode 4 and the second pressure detection electrode 5, and is guided to the outside of the case 1.

Next, the operation of this pressure detecting capacitor will be described. In the initial state depicted in FIG. 1, the first pressure detection electrode 4 and the second pressure detection electrode 5 are made of a dielectric material 6.
Is only in contact with its convex part. Therefore, the contact area between the two is small, and the electrostatic capacitance between the first pressure detection electrode 4 and the second pressure detection electrode 5 has a relatively small value.

When pressure is applied to the portion of the pressure transmitting member 2 protruding from the case 1, the pressure transmitting surface of the pressure transmitting member 2 pushes the periphery of the second pressure detecting electrode 5. Since the dielectric 6 is formed in the shape of a convex lens, the second pressure detection electrode 5 bends following the curved surface of the dielectric 6 and gradually increases the contact area. At this time, since the dielectric 6 is also slidable in the direction in which the pressure is applied, the first pressure detection electrode 4 is pushed at the center thereof, so that the first pressure detection electrode 4 also moves on the curved surface of the dielectric 6. It will bend and increase the contact area. By applying the pressure in this way, the first pressure detection electrode 4 and the second pressure detection electrode 5 and the dielectric 6
The contact area with and increases, and the capacitance also continuously increases accordingly.

Next, a second embodiment of the pressure detecting capacitor will be described with reference to FIG. Dielectric 26, first
The pressure detection electrode 24 and the second pressure detection electrode 25 are the same as those in the first embodiment. The portion of the first pressure transmitting member 22 that contacts the second pressure detecting electrode 25, that is, the pressure transmitting surface has the same shape as the pressure transmitting member according to the first embodiment. A pair of switch electrodes 27 is provided on the surface opposite to the pressure transmission surface. This switch electrode 2
Reference numeral 7 is a conductor formed with a pattern as shown in FIG. 3, for example, and the conductive member provided separately provides a function as a switch. Such electrode patterns configured as switches are known. Reference numeral 23 is a second pressure transmission member, and a conductive electrode 28 is provided on the surface facing the switch electrode 27. Conductive electrode 28
Is for making a short circuit between the electrodes by coming into contact with the switch electrode 27, and is made of a conductive material such as conductive rubber.

These members are housed in the case 21 as shown in the figure. The shape of the portion of the case 21 in which the first pressure detection electrode 24 is housed is processed in the same manner as in the first embodiment. Each member is housed so as to be slidable in the direction in which pressure is applied, that is, in the horizontal direction in the figure. A spring 29 is provided between the first pressure transmission member 22 and the second pressure transmission member 23.
Is provided to prevent the switch electrode 27 and the conductive electrode 28 from contacting each other in the initial state, and the first pressure transmission member 22 is provided.
The second pressure detection electrode 25 is pressed against the dielectric 26 with a small pressure. Further, a part of the rear end of the second pressure transmitting member 23 projects from the case 21 so that external pressure can be applied. One of the second pressure detecting electrode 25 and the switch electrode 27 is electrically connected, and the terminal 30 is connected to the other one of the first pressure detecting electrode 24 and the switch electrode 27 and is guided to the outside of the case 21. There is.

In this embodiment, the spring constants of the spring 29, the first pressure detecting electrode 24 and the second pressure detecting electrode 25 are set as follows. Qualitatively speaking, the spring 29 is made softer than the first pressure detection electrode 24 and the second pressure detection electrode 25, and when the pressure applied to the second pressure transmission member 23 is increased, First, the conductive electrode 28 contacts the switch electrode 27, and thereafter, the first pressure detection electrode 24 and the second pressure detection electrode 25.
The relationship must be such that

Next, the operation of the pressure detecting capacitor will be described. In the initial state depicted in FIG. 2, the first pressure transmission member 22 and the second pressure transmission member 23 are separated from each other, and the switch electrodes 27 are also open. Therefore, the terminals 30 are in an open state, that is, a switch-off state. At this time, the first pressure detection electrode 24 and the second pressure detection electrode 25 are in contact with the dielectric 26 only at their convex portions. Therefore, the contact area between the two is small, and the electrostatic capacitance between the first pressure detection electrode 24 and the second pressure detection electrode 25 has a relatively small value.

Next, the case 21 of the second pressure transmission member 23.
When a small pressure is applied to the portion projecting from the first, the second pressure transmitting member 23 mainly moves, and the conductive electrode 28 provided at the tip of the second pressure transmitting member 23 comes into contact with the switch electrode 27. In this state, the switch electrodes 27 are connected and a small capacitance is formed between the terminals 30.

When pressure is further applied to the second pressure transmitting member 23, the first pressure transmitting member 22 is pushed, and its pressure transmitting surface pushes the periphery of the second pressure detecting electrode 25. As in the case of the first embodiment, the capacitance increases as the second pressure detection electrode is pushed.

By applying the pressure in this way, first, the switch electrodes 27 are closed to form an electrostatic capacitance between the terminals 30, and the electrostatic capacitance continuously increases as the pressure further increases. become. FIG. 4 shows an example of the pressure-capacitance characteristic of this embodiment. In the example of this figure, when a pressure of 10 g is first applied, the switch is closed to have an initial capacitance of 50 pF, then the capacitance increases as pressure is applied, and when the pressure reaches 500 g, the capacitance becomes 100 pF. Shows. The pressure at which the switch is turned on, the maximum pressure, etc. are set according to the situation where this capacitor is used.

Next, a variation of the above embodiment will be described. First, as the shape of the dielectric, various shapes other than the convex lens shape shown in the first and second embodiments can be considered. In FIG. 5A, only one surface of the dielectric 106 is formed in a convex shape, and the other surface is a flat surface. Therefore, the first pressure detection electrode 104 does not actually have a function of changing the electrostatic capacitance by the pressure. Therefore, the first pressure detection electrode 104 may be fixed to the surface of the dielectric 106 by sintering or the like. Further, since it is not necessary to avoid bending in the portion of the case 101 in which the first pressure detection electrode 104 is housed, it may remain flat as shown in the figure. The other members are the same as those in the above embodiment.

In FIG. 5B, only one surface of the dielectric material 116 is formed in a concave shape, and the pressure transmission surface of the pressure transmission member 112 is processed in a convex shape. The second pressure detecting electrode 115 is in contact with the dielectric 116 around the contact surface in the initial state,
When the central portion is pressed by the pressure transmitting member 112, the dielectric member 116 bends following the concave surface, increasing the contact area with the dielectric member 116 and increasing the capacitance.

In FIG. 5C, both surfaces of the dielectric 126 are formed in a concave shape. In this case, the portion of the case 121 in which the first pressure detecting electrode 124 is housed is processed into a convex shape so as to push the center of this electrode. Further, the shape of the dielectric may be, for example, convex on one side and concave on the other side as shown in FIG. 6, and the surfaces of the pressure transmitting member and the case facing the respective surfaces may be uneven according to the shape of the dielectric. If processed, it can have the same function.

Further, in the above description, the dielectric is formed in a spherical shape, but this is made a cylindrical surface, and other members can also have the same function by pressing the pressure detection electrode against the cylindrical surface. be able to. The pressure transmitting surface of the pressure transmitting member has a ring shape in FIG.
Although the spherical shape is used in (b) and the like, the shape is not limited to this. For example, in the embodiment of FIG. 1, even if some projections are discretely provided around the pressure transmitting surface, the circumference of the second pressure detection electrode 5 can be pushed and the same function can be provided.

Whether the curved surface of the dielectric is spherical or cylindrical, the curved surface shape is determined according to the desired pressure-capacitance characteristic. As shown in FIG. 7, it is also possible to make the capacitance increase uniformly with pressure.
Further, changing the rate of increase depending on the magnitude of pressure is also determined by the curved surface shape of the dielectric. It is possible for the present invention to have such characteristics by forming the contact surface of the dielectric with the electrode by a curved surface.

Next, a third embodiment of the pressure detection coordinate indicator according to the present invention will be described with reference to FIGS. This embodiment is constructed by using the pressure detecting capacitor according to the first embodiment. Reference numeral 50 is a pressure detecting capacitor, and its basic structure is the same as that of the first embodiment. A part of the pressure transmitting member 51 is modified to have this configuration, and a hole and a split for holding the pen core 55 detachably are processed. The pen core 55 is for pointing the input surface of the coordinate reading device. Pen core 5
When 5 is pressed against the input surface, the pressing force is transmitted to the pressure transmitting member 51 of the pressure detecting capacitor 50. Coil 53
Is a wire wound around a ferromagnetic core such as ferrite, and constitutes an LC parallel resonance circuit together with the capacitor 54. The pressure detecting capacitor 50 is connected in parallel to the resonance circuit by a terminal 52 thereof. An equivalent circuit for these connections is shown in FIG. Each member is stored in a pen-shaped case 56. In the figure, only the tip of the pen is shown.

Next, the operation of the pressure detection coordinate indicator will be described. In the initial state where the pen core 55 is not pressed against anything as shown in FIG. 8, no pressure is applied to the pressure transmission member 51. In this state, the pressure detection capacitor 50 has a comparatively small electrostatic capacitance as described in the first embodiment. If the capacitance of the pressure detection capacitor at this time is Cp, the capacitance of the capacitor 54 is C, and the inductance of the coil 53 is L, the resonance frequency fr of the resonance circuit shown in FIG. 9 is well known. The following expression 1 is obtained.

Fr = 1 / (2πsqrt (L (C + Cp))) (Equation 1) Here, sqrt (X) is an operator for obtaining the square root of X. When the pen core 55 is pressed on the tablet, the pressing force is transmitted to the pressure transmitting member 51, and the pressure detecting capacitor 50 has an electrostatic capacity according to the pressure. If the increase in capacitance from the initial state is ΔCp, the resonance frequency fp of the resonance circuit in the new state is given by the following expression 2.

Fp = 1 / (2πsqrt (L (C + Cp + ΔCp))) (Equation 2) As described in the first embodiment, ΔCp is a large value as compared with the conventional pressure detecting capacitor, and therefore the resonance frequency Changes will also be significant. FIG. 10 is an explanatory diagram showing changes in the frequency characteristic of the gain of the closed loop circuit when this coordinate indicator is placed on the tablet shown in FIG. 17 and pressure is applied. In the closed loop circuit, oscillation occurs near the frequency at which the gain peaks (however, the phase rotation needs to be 360 degrees). In the state where no pressure is applied, the frequency characteristic is the curve shown in FIG. As the pressure increases, this curve continuously changes to the lower frequency, such as (b), (c), and (d). The oscillation frequency greatly changes depending on the pressure, and this change amount is larger than that of the conventional pressure detection coordinate indicator.

Next, a fourth embodiment of the pressure detection coordinate indicator according to the present invention will be described with reference to FIGS. 11 to 13. This embodiment is constructed by using the pressure detecting capacitor according to the second embodiment. Reference numeral 60 is a pressure detecting capacitor, and its basic structure is the same as that of the second embodiment. The second pressure transmitting member 61 has the third
Similar to the above embodiment, a hole and a split for holding the pen core 65 detachably are processed. Pressure detection capacitor 60
The other members are basically the same as those in the third embodiment. The connection equivalent circuit of this embodiment is as shown in FIG. 12, which is a circuit in which a switch is connected in series to a capacitor section for detecting pressure.

Next, the operation of the pressure detection coordinate indicator will be described. In the initial state where the pen core 65 is not pressed against anything as shown in FIG.
No pressure is applied to. In this state, as described in the second embodiment, the switch portion of the pressure detecting capacitor 60 is open, and the resonance circuit shown in FIG. 12 is a circuit including only the coil 63 and the capacitor 64. Therefore, if the capacitance of the capacitor 64 is C and the inductance of the coil 63 is L, the resonance frequency fr of this resonance circuit is given by the following expression 3.

Fr = 1 / (2πsqrt (LC)) (Equation 3) When the pen core 65 is pressed with a weak force on the tablet, the pressing force is transmitted to the second pressure transmission member 61, and the switch is closed. Therefore, the pressure detection capacitor is connected to the resonance circuit with a relatively small capacitance. It is the same as the third embodiment that the electrostatic capacity increases in accordance with the pressure when further pressure is applied.

FIG. 13 is an explanatory diagram showing changes in the frequency characteristic of the gain of the closed loop circuit when pressure is applied as in the case of the third embodiment. In the state where no pressure is applied, the frequency characteristic is the curve shown in FIG. When the pressure increases and the switch is closed, the resonance frequency changes discontinuously to the state of (b). After that, as the pressure increases, this curve continuously changes to the lower frequency, such as (b), (c), and (d). Switch on /
It is characteristic that the change in frequency characteristics causes a jump due to turning off.

Next, a variation of the above embodiment will be described. The coordinate indicator according to the third and fourth embodiments is called a stylus pen housed in a pen-shaped case. In addition to this, the coordinate reading device also has a coordinate indicator called a cursor. In this case, the operating member may have a button shape, for example, and the pressure may be transmitted by pressing this button.

Although the coordinate reading device whose principle of operation is closed-loop oscillation is shown as the background art of the present invention, the present invention is characterized in that the resonance frequency of the coordinate indicator is largely changed by pressure. The principle of the coordinate reading device is not limited.

Further, although the physical quantity to be detected in the present invention is specified as pressure, the pressure is physically detected as a minute displacement, and the present invention is also used for displacement detection. It is valid.

[0048]

As described above, according to the first structure of the present invention, the dielectric having the concave or convex curved end face is sandwiched by the pair of pressure detecting electrodes, and the pressure transmitting electrode is used to insulate the pressure detecting electrodes. The capacitance between the pressure detection electrodes was changed by bending the body along the curved surface and changing the contact area. For this reason, it was possible to realize a pressure detection capacitor whose capacitance continuously and largely changes with pressure.

In addition, in the second configuration, in addition to the first configuration, a pair of switch electrodes connected in series to the pressure detection electrode, a second pressure transmission member, and a second pressure transmission member facing the switch electrode are provided. The pressure transmitting member of No. 2 was provided with a conductive member. For this reason, it was possible to realize a pressure detection capacitor in which the electrostatic capacitance is continuously changed greatly by turning on / off the electrostatic capacitance with a small pressure and further increasing the pressure.

In the third configuration, the pressure detecting capacitor according to the first configuration is connected in parallel to the parallel resonance circuit of the coordinate indicator which is used in the electromagnetic induction type coordinate reader and has the parallel resonance circuit including the coil and the capacitor. Further, an operation member for transmitting an operation pressure to the pressure transmission member by operation is provided to constitute a pressure detection coordinate indicator. Therefore, it was possible to realize a pressure detection coordinate indicator capable of continuously and greatly changing the resonance frequency depending on the operating pressure.

Further, in the fourth structure, the pressure detecting coordinate indicator is constituted by using the pressure detecting capacitor of the second structure as the pressure detecting capacitor of the third structure.
For this reason, it was possible to realize a pressure detection coordinate indicator capable of discontinuously changing the resonance frequency in a state where the operating pressure is small, and further increasing the pressure to continuously change the resonance frequency. .

[Brief description of drawings]

FIG. 1 is a first part of a pressure detecting capacitor according to the present invention.
It is a block diagram of the Example of.

FIG. 2 is a second part of the pressure detecting capacitor according to the present invention.
It is a block diagram of the Example of.

FIG. 3 is a plan view of a switch electrode according to a second embodiment.

FIG. 4 is a graph of pressure-capacitance characteristics in the second embodiment.

FIG. 5 is a configuration diagram showing a variation of the shape of the dielectric of the pressure detection capacitor according to the present invention.

FIG. 6 is a configuration diagram showing a variation of the shape of the dielectric of the pressure detection capacitor according to the present invention.

FIG. 7 is a graph of pressure-capacitance characteristics of the pressure detection capacitor according to the present invention.

FIG. 8 is a third embodiment of the pressure detection coordinate indicator according to the present invention.
It is a block diagram of the Example of.

FIG. 9 is an equivalent circuit diagram of a pressure detection coordinate indicator according to a third embodiment.

FIG. 10 is an explanatory diagram of frequency characteristics of gain of a closed loop circuit of a coordinate reading device using a pressure detection coordinate indicator according to a third embodiment.

FIG. 11 is a configuration diagram of a fourth embodiment of the pressure detection coordinate indicator according to the present invention.

FIG. 12 is an equivalent circuit diagram of a pressure detection coordinate indicator according to a fourth embodiment.

FIG. 13 is an explanatory diagram of frequency characteristics of gain of a closed loop circuit of a coordinate reading device using a pressure detection coordinate indicator according to a fourth embodiment.

FIG. 14 is a diagram illustrating a configuration of a conventional pressure detection capacitor.

FIG. 15 is an explanatory diagram of a configuration of a conventional pressure detecting capacitor.

FIG. 16 is a diagram illustrating the principle of a coordinate reading device that is the background of the present invention.

FIG. 17 is a principle explanatory diagram of a pressure detection coordinate indicator which is the background of the present invention.

[Explanation of symbols]

1, 21, 101, 111, 121 Case 2, 102, 112, 122, 132, 142 Pressure transmission member 22 First pressure transmission member 23 Second pressure transmission member 4, 24, 104, 114, 124, 134, 144
First pressure detection electrode 5, 25, 105, 115, 125, 135, 145
Second pressure detection electrodes 6, 26, 106, 116, 126, 136, 146,
903, 913 Dielectric 27 Switch electrode 28 Conductive electrode 9, 29 Spring 10, 30 Terminal 50, 60 Pressure detection capacitor 51 Pressure transmission member 61 Second pressure transmission member 52, 62 Terminal 53, 63 Coil 54, 64 Capacitor 55, 65 Pen core 56, 66 Pen case 901, 902 Electrode 904, 905 Elastic body 911 First electrode 912 Second electrode 916 Spacer 917 Pressing body 920 Tablet 921 Sense line 922, 932 Coordinate indicator 923, 933 Resonance circuit 924 Amplification circuit 935 Pressure detection capacitor

Claims (4)

[Claims] 1. A pair of pressure detection electrodes and one or two contact surfaces which are concave so as to be sandwiched between the pressure detection electrodes and contact a part of the contact surface with the pressure detection electrodes in an initial state. Alternatively, the pressure transmitting surface is formed in a convex shape or a concave shape corresponding to the unevenness of the dielectric formed on the convex curved surface and the contact surface of the dielectric, and a pressure is applied to the pressure detecting electrode by the pressure transmitting surface. And a pressure transmitting member provided so as to change the contact area between the pressure detecting electrode and the dielectric according to the magnitude of pressure, and the capacitance between the pair of pressure detecting electrodes is the pressure. A pressure detection capacitor designed to change depending on the size of. 2. A pair of pressure detection electrodes, and one or two surfaces of the contact surface are concave so as to be sandwiched between the pressure detection electrodes and contact a part of the contact surface with the pressure detection electrode in an initial state. Alternatively, the pressure transmitting surface is formed in a convex shape or a concave shape corresponding to the unevenness of the dielectric formed on the convex curved surface and the contact surface of the dielectric, and a pressure is applied to the pressure detecting electrode by the pressure transmitting surface. A first pressure transmitting member that is provided so as to change the contact area between the pressure detecting electrode and the dielectric depending on the magnitude of the pressure, and an opposite side of the pressure transmitting surface of the first pressure transmitting member. A pair of electrodes provided on the side surface, one of which is a switch electrode electrically connected to one of the pressure detecting electrodes, and the pressure transmits the pressure to the first pressure transmitting member. A second pressure transmitting member,
A conductive member that is provided on a surface of the second pressure transmitting member that faces the switch electrode and that is provided so as to contact the switch electrode when pressure is applied to connect the switch electrodes. When the pressure is applied to the second pressure transmitting member, the switch electrodes are connected to each other, and when the pressure is further applied, the pressure is transmitted to the first pressure transmitting member, and the pressure detecting electrode is formed. Pressure detection capacitor, wherein the capacitance between the other electrode not connected to the switch electrode and the other electrode not connected to the pressure detection electrode of the switch electrode changes according to the magnitude of pressure. . 3. A coordinate indicator for use in an electromagnetic induction type coordinate reading device, comprising a parallel resonance circuit including a coil and a capacitor, which is sandwiched between a pair of pressure detecting electrodes and the pressure detecting electrodes and is in an initial state. Then, the pressure-detecting electrode and a part of the contact surface are in contact with each other, and one or two surfaces of the contact surface have concave or convex curved surfaces. The pressure transmitting surface is formed in a convex shape or a concave shape, the pressure is transmitted to the pressure detecting electrode by the pressure transmitting surface, and the contact area between the pressure detecting electrode and the dielectric is changed according to the magnitude of the pressure. A pressure transmission member provided in such a manner that the capacitance between the pair of pressure detection electrodes is connected in parallel to the parallel resonance circuit, the pressure detection capacitor being configured to change depending on the magnitude of pressure. Push further A pressure detection coordinate indicator provided with an operating member for transmitting the pressure by the downward operation to the pressure transmitting member. 4. A coordinate indicator used in an electromagnetic induction type coordinate reading device, having a parallel resonance circuit of a coil and a capacitor, which is sandwiched between a pair of pressure detection electrodes and the pressure detection electrodes, and is in an initial state. Then, in order to contact the pressure detecting electrode with a part of the contact surface, one or two surfaces of the contact surface are formed into a concave or convex curved surface, and the contact surface of the dielectric body has irregularities. The pressure transmitting surface is formed in a convex shape or a concave shape, and the pressure transmitting surface transmits pressure to the pressure detecting electrode, and the contact area between the pressure detecting electrode and the dielectric changes depending on the magnitude of the pressure. And a pair of electrodes provided on a surface of the first pressure transmission member opposite to the pressure transmission surface of the first pressure transmission member, one electrode of which is the pressure detection electrode. For switches electrically connected to one side An electrode and a second pressure transmitting member that transmits pressure to the first pressure transmitting member by pressure.
A conductive member that is provided on a surface of the second pressure transmitting member that faces the switch electrode and that is provided so as to contact the switch electrode when pressure is applied to connect the switch electrodes. When the pressure is applied to the second pressure transmitting member, the switch electrodes are connected to each other, and when the pressure is further applied, the pressure is transmitted to the first pressure transmitting member, and the pressure detecting electrode is formed. Pressure detection capacitor, wherein the capacitance between the other electrode not connected to the switch electrode and the other electrode not connected to the pressure detection electrode of the switch electrode changes according to the magnitude of pressure. Is connected in parallel to the parallel resonance circuit, and the pressure due to the pressing operation is applied to the second resonance circuit.
Pressure detecting coordinate indicator provided with an operating member for transmitting to the pressure transmitting member.