JPH062440U - Cordless digitizer - Google Patents

Abstract

(57) [Summary] [Purpose] The width of the loop coil of a self-oscillating cordless digitizer can be configured to an arbitrary size to increase the measurable height of the position indicator. [Structure] A conductor group in each direction is formed in a strip shape, and a loop coil having an arbitrary width is formed by switching means in each direction. .

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a digitizer for reading designated position coordinates on a surface, and more particularly to a so-called cordless digitizer in which a position indicator for designating a position to be read is not connected to a tablet body.

[0002]

[Prior art]

 Conventional cordless digitizers of this type have an oscillator that operates independently in any method. For example, in an electromagnetic induction type cordless digitizer, magnetic field coupling between the position indicator and the tablet is used, so even when the position indicator generates a magnetic field, or the tablet generates a magnetic field. In both cases, the system has an oscillator for generating a magnetic field.

[0003]

[Problems to be solved by the device]

 For this reason, in such a device, it is necessary to provide an oscillator, so that there is a drawback that the device is complicated accordingly. In order to eliminate this drawback, the applicant has proposed a self-oscillation type cordless digitizer in the “cordless digitizer” filed on February 21, 1992. In this device, for example, at least two of the loop coil groups provided on the tablet are connected by an amplifier, and a self-oscillation system is configured with a position indicator having either or both of a coil and a capacitor. . When the position indicator is brought close to the tablet, the coil of the position indicator is excited by ambient noise radio waves, etc., and this is a trigger, and it is continuous and stable as if each of the above elements constitutes an oscillator. Oscillates to. Since the output level of the amplifier in this oscillation changes depending on the distance between the position indicated by the position indicator and the loop coil, the indicated position can be detected. Moreover, the oscillation frequency at this time takes a value peculiar to this self-oscillation system. Therefore, the operating state of the position indicator can also be detected by changing the constants of the coil or the capacitor of the position indicator according to the operating state of the position indicator.

By the way, since the above-mentioned device is a system using a loop coil having a constant width, for example, when the position indicator is separated from the tablet surface by a certain distance or more, steady oscillation may stop. There is a drawback that the position of occurrence cannot be measured. This drawback occurs when the position indicator coil is displaced outside the range in which the interaction between the tablet loop coil and the position indicator coil is achieved. In a normal case, if the position indicator is brought close to the tablet, self-oscillation will occur again, so this will not cause a problem, but when the cardboard is placed on the tablet surface and used, the position of the tablet surface In some cases, the distance from the indicator coil cannot be maintained within the above interaction range. In such a case, there is a disadvantage that the position cannot be measured.

[0005]

[Means for Solving the Problems]

 Therefore, in this invention, when the plurality of conductors arranged on the tablet are connected by the amplifier and the coil arranged on the position indicator is brought close to the tablet, the plurality of conductors, the amplifier and the position of the tablet are In the cordless digitizer in which the indicator coil constitutes a self-oscillation system having a unique frequency characteristic, and the pointing position information of the position indicator is obtained from the output of the amplifier of the self-oscillation system, the indicator is placed on the tablet. A plurality of conductors are formed in strips at substantially equal intervals, and switching means that can be selected for each of the strip-shaped coils is provided. The switching means operates to select at a predetermined measurement timing. A loop coil group having a space is formed, and the loop coil group is configured to act as a plurality of conductors of the self-oscillation system. .

[0006]

[Action]

 By increasing the width of the tablet loop coil, the interaction range between the tablet surface and the position indicator coil can be increased.

[0007]

【Example】

 1 to 5 show the configuration of an electromagnetic induction type cordless digitizer according to the present invention. FIG. 1 is an explanatory diagram showing the overall configuration of the digitizer, and FIG. 2 is an X formed on the tablet of the digitizer. Direction conductor group, FIG. 3 is a Y direction conductor group formed on the tablet of the digitizer, FIG. 4 is an explanatory view showing a scanning operation of each loop coil group shown in FIGS. 2 and 3, and FIG. 3 is an explanatory diagram showing an example of a position detecting method of the digitizer shown in FIG. 1. FIG.

First, the configuration of the X-direction conductor group and the Y-direction conductor group of the digitizer according to the present invention will be described with reference to FIGS. 2 and 3. As shown in FIG. 2, the tablet 1 is formed with Y-direction conductor groups (x1, x2, x3, ..., Xn) extending in the Y direction and sequentially arranged at a predetermined interval in the X direction. ing. One end of these Y-direction conductor groups is connected to the common conductor x11, and the other end is connected to the X-direction switching means 11. This X-direction switching means 11 has a first X-direction switching circuit 111 connected to the voltage amplifier 13 of the amplification means shown in FIG. 1 and a second X-direction switching circuit 112 connected to ground. . All other X-direction conductors except the X-direction conductors x1 and xn at both ends are connected together to the first and second X-direction switching circuits 111 and 112 through their branch connections, and the left-end X-direction conductors are connected. x1 and the rightmost X-direction conductor xn are connected to the first X-direction switching circuit 111 and the second X-direction switching circuit 112, respectively. Therefore, the conductors other than the X-direction conductors x1 and xn at both ends are configured to be switchably connectable in any of the switching circuits 111 and 112. Now, it is assumed that the first X-direction switching circuit 111 selects the contact x1. The second switching circuit 112 can be connected to any conductor other than the conductor x1. As shown, when the second switching circuit 112 selects the contact x2, a loop coil composed of the conductor x1, the common conductor x11, and the conductor x2 is formed. When the second switching circuit 112 selects the contact x3, the conductor x1, the common conductor x11, and the conductor x3 can form a loop coil that is almost twice as large as the previous loop coil. By selecting the desired X-direction conductor by the second X-direction switching circuit 112, a loop coil having a desired width can be formed. Furthermore, the first X-direction switching circuit 111 can select a contact other than the contact x1. For example, if the switching circuit 111 selects the contact x5 and the second X direction switching circuit 112 selects the contact x6, a loop coil formed by the conductor x5, the common conductor x11, and the conductor x6 is formed. . By arranging the conductor groups in this way, a loop coil having an arbitrary width and an arbitrary position can be formed. The conductor configuration of FIG. 3 is a conductor group configuration in the Y direction, and its operation and operation are similar to those of the conductor group configuration in the X direction described above, and a loop coil having an arbitrary width and position can be selected. The output signal of the current amplifier 14 shown in FIG. 1 is supplied to the loop coil formed by the Y-direction conductor group via the first Y-direction switching circuit 113. Next, the configuration and operation of other parts of this device will be described. In the apparatus shown in FIG. 1, loop coils having desired widths in the X and Y directions are sequentially formed by each direction switching means 11 and 12 in the measurement timing. Therefore, here, the loop coil formed by the conductors y1 and y2 is Y1, the loop coil formed by the conductors y2 and y3 is Y2, the loop coil formed by the conductors y3 and y4 is Y3, ... The loop coil formed by x1 and the conductor x2 is X1, the loop coil formed by the conductor x2 and the conductor x3 is X2, the loop coil formed by the conductor x3 and the conductor x4 is X3, .... . Now, each of these X-side loop coil groups is selectively connected to the X-direction switching circuit 11, and each Y-side loop coil group is selectively connected to the Y-direction switching circuit 12 to form a desired loop coil. The X-direction switching means 11 selectively forms a predetermined X-side loop coil at each timing of measurement based on an X address signal from a control circuit (not shown) and connects it to the input side of the voltage amplifier 13. Under the same Y address signal, a predetermined Y-side loop coil is selectively formed at each measurement timing and connected to the output side of the current amplifier 14. The output signal of the voltage amplifier 13 becomes the input signal of the current amplifier 14. Therefore, in this device, each selectively formed X-side loop coil, the voltage amplifier 13, the current amplifier 14, and each selectively formed Y-side loop coil are connected at a predetermined measurement timing. Then, the output e0 of the voltage amplifier 13 is taken into the utilization circuit 15 and is used for position determination of the position indicator 2, and the output ed of the current amplifier 14 is also subjected to predetermined processing and taken into the utilization circuit 15 to identify the switch. Alternatively, it is used to detect the height (writing pressure) of the position indicator.

In this device, the above-mentioned voltage amplifier 13 is selected to be in a non-saturation region in this self-oscillation system, and the current amplifier 14 is used in a saturation region or saturates in a short time. Is desirable. Since the output e0 of the voltage amplifier 13 is used for position determination, it is desirable to use it in a region where it is not saturated in order to improve the reproducibility of the position, and the output ed of the current amplifier 14 is used for the self-oscillation system. This is because the output is used to drive the loop coil, so a fast rise is desired for stable oscillation of the system. On the other hand, the position indicator 2 has a pen-shaped housing and is configured as a so-called input pen in this embodiment, and includes a coil 21, a first capacitor 221, a second capacitor 222, and a switch 23. There is. The coil 21 of the position indicator 2 is attached so that its inductance is continuously variable, for example, according to the contact pressure of the position indicator 2 on the tablet 1. The second capacitor 222 is connected in parallel to the position indicator 2 via the switch 23 and is used to identify the on / off operation of the switch 23. When this position indicator is positioned on the tablet configured as described above, the coil 21 of the position indicator 2 oscillates in this system due to ambient noise waves or the impact of switching between the direction switching means 11 and 12. Will start.

As shown in FIG. 4, in this device, the Y-direction switching means 12 selectively forms each Y-side loop coil with a predetermined timing and sequentially connects the output side of the current amplifier 14. When the Y-direction switching means 12 selectively forms one of the Y-side loop coils, the X-direction switching means 11 operates to sequentially form each X-side loop coil and input side of the voltage amplifier 13. Connect to. Here, one timing for selecting the X-side loop coil formed by each of the X-direction switching means 11 becomes one measurement timing.

Then, at each measurement timing, the utilization circuit 15 fetches the output e 0 of the voltage amplifier 13 and performs the processing as shown in FIG. FIG. 5 is a schematic diagram showing one method for determining the pointing position of the position pointing device 2 on the tablet 1, which is one of the processes of the utilization circuit 15. As shown in FIG. 4, each output level of the voltage amplifier 13 when the Y-direction switching means 12 selectively forms the loop coil Y1 and the X-direction switching means 11 selectively forms each X-side loop coil (see FIG. 5). ), The Y direction switching means 12 selectively forms the loop coil Y2, and the X direction switching means 11 selectively forms each X side loop coil, each output level of the voltage amplifier 13 (FIG. 5), and the Y direction switching means. 12 selectively forms the loop coil Y3 and the X direction switching means 11 selectively forms each X side loop coil. Each output level of the voltage amplifier 13 (FIG. 5), ... Using the output level of the voltage amplifier 13 at the timing as data, the utilization circuit 15 determines the pointing position of the position pointing device 2 on the tablet 1.

The data fetched by the utilization circuit 15 changes because the capacitance of the capacitor 222 also changes depending on the operating state of the switch 23 of the input pen 2. Further, if the first capacitor 221 is configured to be variable according to the writing pressure, an output corresponding to the writing pressure can be obtained. Therefore, also in this point, the utilization circuit 15 can detect the operation state of the input pen 2 by measuring the frequency component of the output data. As described above, in this device, the contact pressure of the input pen 2 with respect to the tablet 1 or the on / off discrimination of the switch thereof can be identified. Further, as described above, by constructing such frequency analysis based on the output signal ed of the current amplifier 14, there is an advantage that a sufficiently large output signal can be used for the frequency analysis, and at the same time, for determining the position. Since the signal is different from the signal, the operation state of the input pen 2 can be detected independently of the position determination, which has the advantage of simplifying the circuit configuration.

Although the above-mentioned device belongs to the electromagnetic coupling type, it can also be applied to a so-called electrostatic coupling type digitizer. In this case, the loop coil as described above may be used as an electrode for electrostatic coupling, or a conductor may be simply used.

[0017]

[Effect of device]

 As described above, according to the present invention, since the loop coil, which is a component of the self-oscillation system, can be formed with an arbitrary width, the usage condition of the digitizer (for example, placing a thick one on the tablet surface) A self-oscillating cordless digitizer that can increase the measurable height position of a position indicator such as an input pen by performing control to widen each loop coil according to the Can be revealed.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an overall configuration of a cordless digitizer showing one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the configuration of a conductor group in the X direction of the present invention.

FIG. 3 is an explanatory view showing a configuration of a Y-direction conductor group of the present invention.

FIG. 4 is an explanatory diagram showing a scanning operation of the digitizer shown in FIG.

5 is a schematic diagram showing an example of a position determining method of the digitizer shown in FIG.

[Explanation of symbols]

 1: Tablet 2: Position indicator

Claims (1)

[Scope of utility model registration request] 1. A plurality of conductors arranged on a tablet are connected by an amplifier, and when a coil arranged on a position indicator is brought close to the tablet, a plurality of conductors on the tablet, an amplifier and a coil of the position indicator are provided. In a cordless digitizer in which a self-oscillation system having a unique frequency characteristic is configured to obtain pointing position information of the position pointing device from the output of the amplifier of the self-oscillation system. Loop coils which are formed in strips at substantially equal intervals, are provided with switching means that can be selected for each of the coils formed in the strips, and the operation of the switching means causes the loop coil to have a spacing selected at a predetermined measurement timing. Cordless digitizer, in which groups are formed and the loop coils are configured to act as a plurality of conductors of the self-oscillating system .