JPH0741633U - Cordless digitizer - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a cordless digitizer capable of detecting writing pressure with a simple configuration. [Structure] In a cordless digitizer having first and second oscillating elements provided on a tablet and a third oscillating element provided on a position indicator, a coil body constituting the third oscillating element is pressed with a pen. The circuit constant is changed by compressing / expanding in accordance with the.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a cordless digitizer for reading position coordinates on a tablet surface designated by a wireless position indicator, and more particularly to a device having a pen-shaped position indicator pen pressure detection mechanism.

[0002]

[Prior art]

 Conventionally, there was a cordless digitizer having a writing pressure detection mechanism, which was filed by the applicant of the present application in Japanese Patent Application No. 4-171798 (hereinafter referred to as a conventional device). This conventional device will be described with reference to FIGS. First, refer to FIG. This conventional device is composed of a tablet 1 and a position indicator 2. The tablet 1 includes an X-axis scanner 11 in which X-side loop coils X1, X2, ... Are sequentially connected, and a Y-axis scanner 12 in which Y-side loop coils Y1, Y2 ,. The signal from the X-axis scanner 11 is input, the voltage amplifier 13 that amplifies the input signal with a predetermined amplification factor, and the signal from the voltage amplifier 13 are input, and after the input signal is amplified to the saturation region, The current amplifier 14 that outputs this amplified signal to the Y-axis scanner 12 and the output signals from the voltage amplifier 13 are fetched, and based on the fetched output signals, detection of the pointing coordinates of the position indicator 2 and pointing information And a utilization circuit 15 for identifying The X-axis scanner 11 sequentially selects one of the X-side loop coils X1, X2, ... According to the input X-address, and the Y-axis scanner 12 selects the Y-axis according to the input Y-address. One of the side loop coils Y1, Y2, ... Is sequentially selected. The position indicator 2 is selectively connected in parallel with the first coil 211, the first capacitor 212 connected to the first coil 211, and the first capacitor 212 by operating the switch 26. A third capacitor 261 which is variable, a second coil 221 whose distance from the first coil is variable according to the writing pressure of the position indicator 2, and a second coil 221 which is connected to the second coil 221. It has a capacitor 222 and constitutes a tuning circuit composed of a coil and a capacitor.

In this conventional device, when the position indicator 2 is positioned at an arbitrary position on the tablet 1 and the X-side and Y-side loop coils corresponding to the positioned positions are selected. A flow path is formed between the X-side loop coils X1, X2, ... And the Y-side loop coils Y1, Y2 ,. Therefore, when the position indicator 2 is positioned at an arbitrary position on the tablet 1, the X-side loop coil X1, the switching pulse of the X-axis and Y-axis scanners 11 and 12, ambient noise, etc. X2, ... (first oscillating element), the voltage amplifier 13 and the current amplifier 14 (second oscillating element), the Y-side loop coils Y1, Y2, ... (first oscillating element), the above An oscillation system including the tuning circuit (third oscillation element) of the position indicator 2 is configured. The utilization circuit 15 takes in the output from the voltage amplifier 13 and calculates the indicated coordinate value of the position indicator 2 based on the X and Y addresses when the oscillation system is constructed and the output level at that time. At the same time, based on the oscillation frequency of the oscillation system, the operation information of the position indicator 2 including the writing pressure information of the position indicator 2 or the on / off information of the switch 26 is identified. With respect to the oscillation frequency, the oscillation frequency is determined by the circuit constant of the oscillation system. Therefore, in the no-load state in which the switch 26 is not operated or the writing pressure is not applied, the circuit constant of the tuning circuit of the position indicator 2 is constant, and there are no other factors that change the circuit constant. The above oscillation system oscillates at a predetermined oscillation frequency. Then, the position indicator 2 changes the circuit constant of the tuning circuit in response to the operation of the switch 26 or the application of the writing pressure, and changes the oscillation frequency of the oscillation system. The utilization circuit 15 identifies the operation information of the position indicator 2 by detecting the fluctuation of the oscillation frequency of the oscillation system.

Next, please refer to FIG. FIG. 5 is a diagram showing a specific configuration of the position indicator 2. In the same figure, the previously described mechanisms are designated by the same reference numerals. In the figure, 23 is a ferrite core, 24 is a pen core, 25 is an elastic member such as a spring or a leaf spring, and 27 is a housing. The ferrite core 23 is attached to the upper portion of the pen core 24. The ferrite core 23 is attached via the elastic member 25 and is held so as to be vertically movable. The first coil 211 is fixed to the lower portion of the ferrite core 23. On the other hand, the second coil 221 is attached to the upper portion of the ferrite core 23. The second coil is fixed to the housing 27, and the ferrite core 23 penetrates the central portion of the second coil. Therefore, when the pen tip 24 comes into contact with the tablet 1 and a writing pressure is applied from there, the ferrite core 23 relatively moves in the vertical direction according to the strength of the writing pressure. The distance between the first coil 211 and the second coil 222 changes. The change in the distance between the two coils changes the mutual inductance between the two coils, and as a result, changes the circuit constant of the tuning circuit in the position indicator 2.

[0005]

[Problems to be solved by the device]

 In the above conventional device, as described above, the circuit constant of the tuning circuit is changed by changing the distance between the first coil 211 and the second coil 221 to detect the writing pressure. It was This device is suitable because it can detect the pen pressure with a simple mechanism. As a result of further studies, the applicant of the present invention has newly devised a cordless digitizer capable of detecting writing pressure with a function equivalent to that of the conventional device, that is, a simple structure, and proposes it here.

[0006]

[Means for Solving the Problems]

 A cordless digitizer of the present invention comprises a tablet and a pen-shaped position indicator, and a first oscillating element disposed on the tablet and a second oscillating element coupled to the first oscillating element. And a third oscillating element provided in the position indicator, and when the position indicator is positioned at an arbitrary position on the tablet, the first, second and third oscillating elements are In a cordless digitizer that constitutes an oscillation system and is configured to identify the operation information of the position indicator based on the oscillation frequency of the oscillation system, a coil body as a component of the third oscillation element, A coil body expanding / contracting means provided in the position indicator, for compressing and expanding the coil body according to a writing pressure applied to the tablet by the position indicator, and changing the inductance of the coil body; and the oscillation system. And a writing pressure detecting means for detecting the writing pressure as the operation information based on the oscillation frequency of the oscillation system that has changed due to the change in the inductance. Is.

[0007]

[Action]

 The coil length of the coil body changes according to the writing pressure of the position indicator by the coil body compression / expansion means. The inductance of the coil itself changes according to the change of the coil length, and the circuit constant of the third oscillating element changes. Therefore, the oscillation frequency of the oscillation system changes according to the change in the coil length of the coil. The writing pressure detection means detects the changed oscillation frequency of the oscillation system to detect the writing pressure of the position indicator.

[0008]

【Example】

 Hereinafter, an apparatus according to an embodiment of the present invention will be described with reference to FIGS. Please refer to FIG. FIG. 1 is a diagram showing a first embodiment device of the present invention, which is a diagram showing the structure of a position indicator 2 and corresponds to FIG. 5 described above. In the present invention, the tablet 1 has the same configuration as the conventional device (see FIG. 6) and the same pen pressure detecting means, so the description thereof will be omitted and the above-mentioned position indication will be omitted. The device 2 will be explained. In FIG. 1, the same parts as those shown above are indicated by the same reference numerals. In the figure, 241 is a support portion provided on the upper end surface of the pen core 24, and 271 is a first protrusion 271 formed as a part of the housing 27.

The lower end of the pen core 24 is exposed at the lower part of the housing 27, and the pen core 24 relatively moves in the vertical direction according to the application of writing pressure. A ferrite core 23 is arranged on the peripheral surface portion of the pen core 24 extending from the central portion to the upper portion. Since the ferrite core 23 and the pen core 24 are fixed to each other, when the writing pressure is applied to the pen core 24, the ferrite core 23 moves relatively upward together with the pen core 24. A first coil 211 is wound around the peripheral surface of the ferrite core 23. The first coil 211 is bonded to the ferrite core 23. Then, one end of this first coil 211 is connected to the first capacitor 212, and the other end is connected to the second coil 221. Further, the second coil 211 and the first capacitor 212 are connected to each other. Therefore, the first coil 211, the second coil 221, and the first capacitor 212 are connected in a loop shape to form a tuning circuit. This tuning circuit corresponds to the third oscillating element in the conventional device. The second coil 221 is arranged between the pen core 24 and the first protrusion 271. The upper end of the second coil 221 contacts the first protrusion 271 and the lower end of the second coil 221 is the pen core. It is in contact with the support portion 241 which is the upper end portion of 24. The second coil 211 pushes the pen core 24 downward by its own elastic force. Therefore, in the device of the first embodiment, the second coil 221 also functions as an elastic member for the pen core 24. An elastic member for pushing down the pen core 24 downward is separately provided between the support portion 241 and the first protrusion 271, and the second coil 221 is arranged so as to surround the elastic member. May be. With this configuration, the degree of freedom in selection for the second coil 221 is improved. In this case, it is desirable to use a non-conductive member such as a plastic damper for the elastic member. This is because by using a non-conductive member, it is possible to prevent current loss when a current is induced in the second coil 221 (during tuning).

In the apparatus of the first embodiment, when pen pressure is applied to the pen core 24, the pen core 24 moves relatively upward. With this movement, the second coil 221 is compressed. That is, when the normal writing pressure is not applied, the length of the second coil 221 in the expansion / contraction (vertical) direction is L1 as shown in FIG. When the pen pressure is applied and the pen core 24 moves relatively upward, the length of the second coil 221 in the expansion / contraction direction is compressed to L2, as shown in FIG. Then, when the state of FIG. 2 is changed to the unloaded state (the position indicator is separated from the tablet), the second coil 221 pushes down the pen core 24 by its elastic force and returns to the state of FIG. To do.

As described above, the expansion and contraction of the second coil 221 changes the circuit constant of the tuning circuit. This is for the following reason. That is, in a tuning circuit composed of a coil and a capacitor, its circuit constant is determined by the inductance of the coil and the capacitance of the capacitor. The inductance of the coil is determined by the total length of the coil (length in the expansion / contraction direction in the apparatus of the embodiment), the number of turns of the coil, the wire diameter of the coil, and the distance between adjacent coils. Therefore, by expanding and contracting the coil, the total length of the coil and the interval between adjacent coils are changed. In response to this change, the inductance of the coil changes, and as a result, the circuit constant of the tuning circuit changes. Therefore, the oscillation frequency of the oscillation system (see the conventional device) changes according to the change in the writing pressure of the position indicator 2. This is because the circuit constant of the tuning circuit in the position indicator 2 changes according to the change of the writing pressure, which changes the circuit constant of the oscillation system. The writing pressure detecting means (the utilization circuit 15 in the conventional device) detects the writing pressure by detecting the change in the oscillation frequency.

Next, a second embodiment device of the present invention will be described. The second embodiment device is characterized in that the first coil expands and contracts. Hereinafter, a specific description will be given with reference to FIG. In the second embodiment, the first coil 211 is wound around the ferrite core 23 joined to the pen core 24. The first coil 211 in the device of the second embodiment is arranged in a state of surrounding the peripheral surface of the ferrite core 23, in other words, in a state in which the ferrite core 23 penetrates the inside of the first coil 211. ing. Then, a first capacitor 212 is joined to the first coil 211, and both of them constitute a tuning circuit (third oscillating element). A third protrusion 231 is provided on the peripheral surface of the lower end portion of the ferrite core 23. The third protrusion 231 is in contact with the lower end of the first coil 211 and acts as a stopper for the first coil 211. A second protrusion 272 is arranged so as to surround the peripheral surface of the upper end of the ferrite core 23. The second protrusion is formed as a part of the housing 27, and allows the ferrite core 23 to move in the vertical direction. The second protrusion is in contact with the upper end of the first coil 211, and regulates the upward movement of the first coil 211. Thus, the first coil 211 is arranged between the second protrusion 272 and the third protrusion 231. An elastic member 25 is disposed between the support portion 241 at the upper end of the pen core 24 and the first protrusion 271. This elastic member is a so-called leaf spring or coil spring, and pushes down the pen core 24.

In the apparatus of the second embodiment, when pen pressure is applied, the pen core 24 and the ferrite 23 relatively move upward. At this time, the lower end of the first coil 211 is moved upward by the third protrusion 231. On the other hand, the upper end of the first coil 211 is positioned by the second protrusion 272 at a position in contact with the second protrusion 231. Therefore, when the writing pressure is applied, the first coil 211 is compressed and the coil length is shortened. On the other hand, in the unloaded state, the pen core 24 is pushed down by the elastic member 25, and the first coil 211 also expands by its own elastic force. Therefore, in the device of the second embodiment, the circuit constant of the tuning circuit is varied by compressing / expanding the first coil 211 according to the strength of the writing pressure, and based on the change of this circuit constant. The writing pressure is detected by detecting the fluctuation of the oscillation frequency of the oscillation system.

Next, a third embodiment device of the present invention will be described. This third embodiment device has two sets of tuning circuit systems each consisting of a coil and a capacitor, and by changing the coil length of one of the tuning circuit systems, a tuning circuit system composed of these two sets of tuning circuit systems is provided. The feature is that the circuit constant is changed. Hereinafter, a specific description will be given with reference to FIG. Similar to the first embodiment, the first coil 211 is adhered to the peripheral surface of the ferrite core 23 and moves up and down together with the up and down movement of the ferrite core 23 (pen core 24). A first capacitor 212 is connected to the first coil 211 to form a first tuning circuit system. A second coil 221 is arranged between the support portion 241 provided at the upper end of the pen core 24 and the first protrusion 271. The second coil 221 acts as an elastic member similarly to the device of the first embodiment, and pushes the pen core 24 downward. A second capacitor 222 is connected to the second coil 221 and constitutes a second tuning circuit system.

In the device of the third embodiment having such a configuration, the second coil 221 is compressed / expanded according to the application of the writing pressure, and the coil length is changed. Therefore, the circuit constant of the second tuning circuit system changes according to the application of the writing pressure, and along with this, the tuning circuit composed of the first tuning circuit system and the second tuning circuit system (the third tuning circuit system). Circuit constant of (oscillation element of) changes. Therefore, the writing pressure can be detected by detecting the fluctuation of the oscillation frequency of the oscillation system based on the change of the circuit constant.

[0016]

[Effect of device]

 As described above, the cordless digitizer of the present invention has an advantage that the pen pressure can be detected with a simple structure.

[Brief description of drawings]

FIG. 1 is a diagram showing a specific configuration of a first embodiment device of the present invention.

FIG. 2 is a diagram for explaining the operation of the device according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a specific configuration of a second embodiment device of the present invention.

FIG. 4 is a diagram showing a specific configuration of a third embodiment device of the present invention.

FIG. 5 is a diagram illustrating a conventional device.

FIG. 6 is a configuration diagram showing the overall configuration of the device of the present invention and the conventional device.

[Explanation of symbols]

 1 Tablet 2 Position Indicator 211 First Coil 212 First Capacitor 221 Second Coil 222 Second Capacitor 23 Ferrite Core 24 Pen Core

Claims (1)

[Scope of utility model registration request] 1. A first oscillating element, which comprises a tablet and a pen-shaped position indicator, and is disposed on the tablet, and a second oscillating element coupled to the first oscillating element.
A third oscillating element provided in the position indicator,
When the position indicator is positioned at an arbitrary position on the tablet, the first, second and third oscillating elements constitute an oscillation system, and the position indicator of the position indicator is based on the oscillation frequency of the oscillation system. In a cordless digitizer configured to identify operation information, a coil body as a component of the third oscillating element and the position indicator provided in the coil body are provided in accordance with a writing pressure of the position indicator on the tablet. Based on the oscillating frequency of the oscillating system changed by the change of the inductance, the oscillating frequency of the oscillating system is detected based on the oscillating frequency of the oscillating system. A cordless digitizer having a writing pressure detecting means for detecting writing pressure as operation information.