JP2602878B2 - Input Ben of the coordinate input device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an input pen of a coordinate input device for notifying an operation of an operator capable of continuously changing a parameter other than a coordinate value of a designated position. .

(Prior Art) Conventionally, as an input pen for notifying an operation of an operator capable of continuously changing a parameter other than a coordinate value of a designated position, for example, a pen pressure, a lead housed slidably in a pen axis direction. In some cases, a pressure-sensitive sensor using pressure-sensitive conductive rubber or the like is provided at the rear end of the body, and the pressure (pen pressure) applied to the core is detected by the pressure-sensitive sensor.

(Problems to be Solved by the Invention) However, the input pen requires a cable or the like for extracting detection information (resistance value, voltage value, current value, and the like) of the pressure-sensitive sensor, and operability at the time of input work is good. There was no problem.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an input pen of a coordinate input device that eliminates the above-mentioned problems, does not require a cable or the like, and can obtain information that accurately corresponds to an operation of an operator.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an input pen used in a coordinate input device, which indicates a position to be measured to a tablet and notifies an operation of an operator. A core body that has a ferrite chip, is continuously displaced and restored in the pen axis direction in response to an operation of an operator, and a coil capable of slidably housing the core body therein. A tuning circuit comprising a capacitor connected to the coil, wherein the ferrite chip is disposed near an end of the coil, and the tuning circuit tunes to a radio wave transmitted from the tablet, and controls a displacement of the core body due to an operation. An input pen of a coordinate input device for notifying a tablet by the reflected radio wave is proposed.

(Operation) According to the present invention, when an operation by the operator is applied, the core body is displaced in the pen axis direction according to the operation, and at this time, the ferrite chip is displaced with respect to the end of the coil, and the displacement is caused. Since the permeability of the coil changes according to the amount and the inductance changes, the tuning frequency of the tuning circuit formed by the coil and the capacitor changes, and this changes the phase and the phase of the induced voltage based on the radio wave transmitted from the tablet. The frequency is changed, and the displacement amount, that is, information corresponding to the operation of the operator is extracted on the tablet side from the radio wave reflected from the coil based on the induced voltage after the change.

(Embodiment) FIG. 1 shows an embodiment of the input pen of the present invention.
In the figure, 11 is a pen shaft made of a nonmetal material such as a synthetic resin, and 12 is a pen shaft.
Is a core body having a ferrite chip 13, 14 is a coil capable of slidably housing the core body 12, 15 is a core holder for holding the rear end of the core body 12, and 16 is a pen shaft A spring which is supported to be slightly displaceable with respect to 11, and 17 is a capacitor.

The coil 14 and the capacitor 17 are connected in series with each other, and constitute a well-known tuning circuit 18.The inductance of the coil 14 and the capacitance value of the capacitor 17 are:
The tuning (resonance) frequency is set to a value at which the frequency becomes approximately a predetermined frequency f0. Here, in a state where the core body 12 is held by the core holder 15, the ferrite chip 13 is located at the end of the coil 14, and when the input pen is operated on a tablet described later, the writing pressure at that time is changed. According to the core
12, that is, the ferrite chip 13 moves, which changes the inductance of the coil 14 and the tuning circuit 18 described above.
Is slightly changed, whereby the tablet is notified of the operation of the operator, in this case, the pen pressure.

FIG. 2 shows an example of a coordinate input device using the input pen 10 described above. In the drawing, 20 is a tablet, 30 is a control circuit, 31 is a signal generation circuit, and 32 and 33 are selections in the X and Y directions. Circuit, 34, 35 are transmission / reception switching circuit, 36 is XY switching circuit, 37
Is a reception timing switching circuit, and 38 is a bandpass filter (BP
F), 39 is a detector, 40 is a low-pass filter (LPF), 41, 42 are phase detectors (PSD), 43, 44 are low-pass filters (LPF), 45,
46 is a drive circuit, 47 and 48 are amplifiers, 49 is a host computer, 50 is a display device, and 51 is an output device.

FIG. 3 shows details of the loop coil group 21 in the X direction and the loop coil group 22 in the direction, which constitute the tablet 20. The X-direction loop coil group 21 includes a large number of, for example, 48
.. 21-48, and a group of loop coils 22 in the Y direction are arranged in parallel and overlapping with each other along the Y direction. The loop coils 22-1, 21-2,.
The loop coil group 21 in the direction and the loop coil group 22 in the Y direction are closely superimposed on each other (however, they are drawn apart for easy understanding in the drawings), and are made of a non-metallic material (not shown). Housed in a case. Here, each loop coil is configured by one turn,
Multiple turns may be provided as needed.

Next, the operation of the device will be described together with its configuration.
First, how radio waves are transmitted and received between the input pen 10 and the tablet 20 and signals obtained at this time will be described with reference to FIG.

The control circuit 30 includes a well-known microprocessor or the like, controls the signal generation circuit 31, and controls switching of each loop coil of the tablet 20 via the selection circuits 32 and 33 according to the flowchart shown in FIG. Also XY
The switching of the coordinate detection direction is controlled by the switching circuit 36 and the reception timing switching circuit 37.
The output values from 0, 43, and 44 are converted from analog to digital (A / D), and the arithmetic processing described later is executed to obtain the coordinate value of the position indicated by the input pen 10, and the phase of the received signal is detected. These are sent to the host computer 49.

The selection circuit 32 is for sequentially selecting one loop coil from the X-direction loop coil group 21. The selection circuit 33 is for sequentially selecting one loop coil from the Y-direction loop coil group 22. And operate according to the information from the control circuit 30.

The transmission / reception switching circuit 34 alternately connects the selected one loop coil in the X direction to the drive circuit 45 and the amplifier 47, and the transmission / reception switching circuit 35 connects the one loop coil in the selected Y direction. Are alternately connected to the drive circuit 46 and the amplifier 48, which operate according to a transmission / reception switching signal described later.

The signal generating circuit 31 has a predetermined frequency f0, for example, a rectangular wave signal A having a frequency of 500 kHz, a signal B obtained by delaying the phase of the rectangular wave signal A by 90 °, a transmission / reception switching signal C having a predetermined frequency fk, for example, 16.625 kHz. A timing signal D is generated. The rectangular wave signal A is sent to the phase detector 41 as it is,
The signal is converted into a sine wave signal E by a low-pass filter (not shown), and further transmitted to one of the driving circuits 45 and 46 via the XY switching circuit 36.The rectangular wave signal B is transmitted to the phase detector 42, The transmission / reception switching signal C is transmitted to a transmission / reception switching circuit.
The reception timing signal D is transmitted to the reception timing switching circuit 37.

Now, assuming that information for selecting the X direction is input from the control circuit 30 to the XY switching circuit 36 and the reception timing switching circuit 37, the sine wave signal E is sent to the driving circuit 45 and converted into a balanced signal. The signal is transmitted to the transmission / reception switching circuit 34.The transmission / reception switching circuit 34 outputs the signal to the selection circuit 32 from the transmission / reception switching circuit 34 in order to switch and connect one of the driving circuit 45 and the amplifier 47 based on the transmission / reception switching signal C. A signal F is a signal F that outputs or does not output a signal of 500 kHz every 32 μsec, which is a time T (= 1 / 2fk).

The signal F is sent to one of the loop coils 21-i (i = 1, 2,..., 48) in the X direction of the tablet 20 via the selection circuit 32. Generates radio waves based on

At this time, when the input pen 10 is held in a substantially upright state, that is, in a used state on the tablet 20, the radio wave excites the coil of the input pen 10 and synchronizes the signal F with the tuning circuit 18. An induced voltage G is generated.

Thereafter, when the signal F enters a period of no signal, that is, a reception period, and the loop coil 21-i is switched to the amplifier 47 side, the radio wave from the loop coil 21-i immediately disappears, but the induced voltage G is reduced. It gradually attenuates according to the loss in the tuning circuit 18.

On the other hand, the current flowing through the tuning circuit 18 based on the induced voltage G causes the coil 14 to emit radio waves. The radio wave is an amplifier
In order to excite the loop coil group 21-i connected to 47 in reverse, an induced voltage by radio waves from the coil 14 is generated in the loop coil group 21-i. The induced voltage is sent from the transmission / reception switching circuit 34 to the amplifier 47 and amplified to the reception signal H only during the reception period, and is further transmitted to the reception timing switching circuit 37.

In the reception timing switching circuit 37, either one of the selection information in the X direction or the Y direction, here, the selection information in the X direction,
A reception timing signal D, which is substantially an inverted signal of the transmission / reception switching signal C, is input. The reception signal H is output when the signal D is at a high (H) level, and the reception signal H is output during a low (L) level. Since nothing is output, a signal I (substantially the same as the reception signal H) is obtained at the output.

The signal I is transmitted to a band filter 38. The band filter 38 is a ceramic filter having a frequency f0 as a unique frequency, and a signal J having an amplitude corresponding to the energy of the frequency f0 component in the signal I. (Strictly, in a state where several signals I are input to the bandpass filter 38 and converged) are transmitted to the detector 39 and the phase detectors 41 and 42.

The signal J input to the detector 39 is detected and rectified,
Low-pass filter with sufficiently low cutoff frequency after signal K
At 40, a voltage value corresponding to almost half of the amplitude, for example, Vx
And transmitted to the control circuit 30.

The voltage value Vx of the signal L depends on the input pen 10 and the loop coil 21.
-A value dependent on the distance to i, here approximately 4 of the distance
Since the value indicates a value inversely proportional to the power and changes when the loop coil 21-i is switched, the control circuit 30 converts a voltage value Vx obtained for each loop coil into a digital value,
By executing the arithmetic processing described later on these, the coordinate value in the X direction of the position indicated by the input pen 10 is obtained.
The coordinate value of the position indicated by the input pen 10 in the Y direction can be obtained in the same manner.

On the other hand, the rectangular wave signals A and B are input to the phase detectors 41 and 42 as detection signals. At this time, if the phase of the signal J substantially matches the phase of the rectangular wave signal A, the phase The detector 41 outputs a signal M1 (substantially the same as the signal K) obtained by inverting the signal J to the positive side, and the phase detector 42 outputs a signal M2 having a symmetrical waveform on the positive side and the negative side. I do.

The signal M1 is converted into a DC signal N1 (substantially the same as the signal L) having a voltage value corresponding to almost half of the amplitude of the signal J, that is, Vx, by the low-pass filter 43 as described above, and is transmitted to the control circuit 30. The signal M2 is converted to a DC signal N2 by the same low-pass filter 44 and sent to the control circuit 30.Here, the positive and negative components of the signal M2 of the phase detector 42 are the same. Therefore, the voltage value of the output of the low-pass filter 44 is 0
[V].

The control circuit 30 converts the output values of the low-pass filters 43 and 44, here the signals N1 and N2, into digital values, and further uses the digital values to perform the arithmetic processing of the following equation (1). The phase difference θ between the signal added to the signal 42, here, J and the rectangular wave signal A is obtained.

θ = −tan ⁻¹ (VQ / VP) (1) where VP indicates a digital value corresponding to the output of the reduction filter 43, and VQ indicates a digital value corresponding to the output of the low-pass filter 44. For example, in the case of the signal J described above,
The voltage value of the signal N1 is Vx, but the voltage value of the signal N2 is 0.
[V], that is, VQ = 0, so that the phase difference θ = 0 °.

By the way, the phase of the signal J is determined by the tuning circuit of the input pen 10.
It changes corresponding to the tuning frequency at 18. That is, when the tuning frequency in the tuning circuit 18 matches the predetermined frequency f0, an induced voltage having a frequency f0 is generated in the tuning circuit 18 during both the signal transmission period and the signal reception period, and the induced current synchronized with the frequency f0. Flows, the frequency and phase of the reception signal H (or I) match the rectangular wave signal A,
The phase of the signal J also matches the rectangular wave signal A.

On the other hand, the tuning frequency in the tuning circuit 18 is a predetermined frequency.
In the case where the frequency does not coincide with f0, for example, a frequency slightly lower than the frequency f0, for example, f1, an induced voltage having a frequency f0 is generated in the tuning circuit 18 during a signal transmission period. Induction current with phase lag flows,
In addition, during the signal receiving period, an induced voltage having a frequency f1 and an induced current synchronized therewith flow, so that the frequency of the received signal H (or I) is slightly lower than the frequency of the rectangular wave signal A. The phase is also slightly delayed. As described above, since the bandpass filter 38 uses only the frequency f0 as the frequency, the frequency shift of the input signal to the lower side is output as a phase delay,
Therefore, the phase of the signal J is further delayed than the received signal H (or I).

On the other hand, when the tuning frequency in the tuning circuit 18 is a frequency slightly higher than the predetermined frequency f0, for example, f2, an induced voltage having a frequency f0 is generated in the tuning circuit 18 during a signal transmission period. An induced current with a phase advance flows through the tuning circuit 18, and an induced voltage having substantially the frequency f2 and an induced current synchronized therewith flow during the signal receiving period. Therefore, the frequency of the received signal H (or I) is The frequency is slightly higher than the frequency of the rectangular wave signal A, and its phase is slightly advanced. In the band-pass filter 38, the shift of the frequency of the input signal to the higher side will be output as the phase advance contrary to the case described above.
The phase of the signal J is further advanced than the reception signal H (or I).

As mentioned above, the tuning frequency of the tuning circuit 18 is
, The phase difference θ determined by the above equation (1) also changes in accordance with the pen pressure. In the present embodiment, the phase difference θ is preset to be about −60 ° when no writing pressure is applied to the input pen 10, and to be about 60 ° when the writing pressure is applied most.

The obtained phase difference θ is added by 40 °, −20 ° to 10
After being converted into phase information having a value in the range of 0 °, the coordinates are transmitted to the host computer 49 together with the coordinate values in the X direction and the Y direction of the designated position. You may do it.)

Next, according to FIGS. 5 to 9, the coordinate detection operation and the phase detection operation and the phase information representing the pen pressure are input to the input pen.
The conversion to the spread of the figure indicating the position indicated by 10 will be described in detail.

First, when the power of the entire apparatus is turned on and the measurement is started, the control circuit 30 transmits information for selecting the X direction to the XY switching circuit.
36 and the reception timing switching circuit 37,
Information for selecting the first loop coil 21-1 among the loop coils 21-1 to 21-48 in the X direction of the tablet 20 is sent to the selection circuit 32, and the loop coil 21-1 is transmitted and received by the transmission / reception switching circuit 34.
Connect to

The transmission / reception switching circuit 34 alternately connects the loop coil 21-1 to the driving circuit 45 and the amplifier 47 based on the transmission / reception switching signal C described above. At this time, the driving circuit 45 operates during the transmission period of 32 μsec in FIG. 500kHz 1 as shown in (a)
Six sine wave signals are sent to the loop coil 21-1 (only five of them are shown in FIG. 4 for convenience of the drawing).

The switching between transmission and reception is repeated seven times for one loop coil, here 21-1, as shown in FIG. 6 (b). The seven transmission and reception repetition periods correspond to one loop coil selection period (448 μsec).

At this time, an induced voltage is obtained from the output of the amplifier 47 every seven reception periods for one loop coil, and this induced voltage is applied to the bandpass filter 38 via the reception timing switching circuit 37 as described above. The signal is transmitted, averaged, and transmitted to the control circuit 30 via the detector 39, the phase detectors 41 and 42, and the low-pass filters 40, 43 and 44.

The control circuit 30 A / D converts and outputs the output value of the low-pass filter 40 and temporarily stores it as a detection voltage depending on the distance between the input pen 10 and the loop coil 21-1, for example, Vx1.

Next, the control circuit 30 sends information for selecting the loop coil 21-2 to the selection circuit 32, connects the loop coil 21-2 to the transmission / reception switching circuit 34, and sets the distance between the input pen 10 and the loop coil 21-2. The detection voltage Vx2 proportional to is obtained and stored. After that, the loop coils 21-3 to 21-48 are similarly sequentially connected to the transmission / reception switching circuit 34 in the same manner, and each loop as shown in FIG. Detected voltages Vx1 to Vx48 depending on the distance in the X direction from the input pen 10 for each coil (however, only a part thereof is shown in an analog representation in FIG. 6C) are stored.

The actual detected voltage is obtained only in the several loop coils before and after the position (xp) where the input pen 10 is placed as a center, as shown in FIG.

The control circuit 30 checks whether or not the voltage value of the stored detection voltage is equal to or higher than a certain detection level. If the voltage value is equal to or lower than the certain detection level, the control circuit 30 again selects each loop coil in the X direction and detects the voltage. Repeat, if it is above a certain detection level, proceed to the next process.

Next, the control circuit 30 sends selection information in the Y direction to the XY switching circuit 36 and the reception timing switching circuit 37, switches the selection circuit 33 and the transmission / reception switching circuit 35 in the same manner as described above, The input pen 10 obtained by A / D converting the output value of the filter 40 and each of the Y-direction loop coils 22-1 to 22-
The detection voltage depending on the distance to 48 is temporarily stored. Thereafter, a level check is performed in the same manner as described above. If the level is equal to or lower than the predetermined detection level, the process returns to the selection and voltage detection of each loop coil in the X direction. As will be described later, the coordinate values in the X and Y directions of the position pointed by the input pen 10 are calculated from the voltage values.

Next, the control circuit 30 controls the loop coil 21-1 in the X direction.
21-48 (or Y-direction loop coils 22-1 to 22-48)
The information for selecting the loop coil (peak coil) for which the maximum detection voltage is obtained is transmitted to the selection circuit 32 (or 33), and the transmission and reception of the radio wave is repeated a plurality of times, for example, seven times. The output values obtained from the bandpass filters 43 and 44 are A / D converted, and the phase difference θ is calculated as described above.

The phase difference θ is added by 40 °, converted into phase information representing the pen pressure, and transferred to the host computer 49 together with the coordinate values in the X and Y directions of the position indicated by the input pen 10 described above.

When the first coordinate detection operation and the phase detection operation are completed in this way, the control circuit 30 performs the second and subsequent coordinate detection operations as shown in FIG. Among the loop coils 21-48, a selection circuit 32 selects information that selects only a fixed number of loop coils around the loop coil at which the maximum detection voltage is obtained, for example, only 10 loop coils.
And the Y-direction loop coils 22-1 to 22-48
Out of the loop coil at which the maximum detection voltage is obtained, a fixed number of values before and after that, and information for selecting only the ten loop coils are sent to the selection circuit 33, and the output value is obtained in the same manner as described above. To perform a coordinate detection operation and a phase detection operation in the X direction and the Y direction of the position indicated by the input pen 10;
The obtained coordinate values and phase information are transferred to the host computer 49, and thereafter, these are repeated.

In addition, if the level check described above is explained in detail,
Check whether the maximum value of the detection voltage has reached the detection level and which loop coil has the maximum value of the detection voltage, and if the detection level has not been reached, stop the subsequent coordinate calculation and the like. This is a process of setting the center of the loop coil to be selected in the next coordinate detection operation and phase detection operation.

X-direction or Y-direction coordinate values, for example, as one method of calculating the coordinate value xp, approximate the waveform near the maximum value of the detection voltage Vx1 ~ Vx48 with a suitable function, the coordinates of the maximum value of the function There is a way to ask.

For example, in FIG. 6 (c), the maximum detection voltage Vx3
And the detection voltages Vx2 and Vx4 on both sides thereof can be calculated as follows by approximation by a quadratic function (however, the coordinate values of the center positions of the loop coils 21-1 to 21-4 are x1 to
x48, and the interval is Δx. ). First, from the respective voltages and coordinate values, Vx2 = a (x2-xp) ² + b (2) Vx3 = a (x3-xp) ² + b (3) Vx4 = a (x4-xp) ² + b ... ... (4) Here, a and b are constants (a <0).

X3−x2 = Δx (5) x4−x2 = 2Δx (6) By substituting the equations (5) and (6) into the equations (3) and (4) and rearranging, xp = x2 + Δx / 2 ｛(3Vx2-4Vx3 + Vx4) / (Vx2-2−Vx3 + Vx4)｝ (7) .

Therefore, the maximum value of the detection voltage obtained at the time of the level check and the detection voltages before and after that are extracted from each of the detection voltages Vx1 to Vx48, and these and the one of the loop coil from which the maximum value of the detection voltage is obtained are extracted. The coordinate value xp of the input pen 10 can be calculated by performing an operation corresponding to the aforementioned equation (7) from the coordinate value (known) of the previous loop coil.

On the other hand, according to the flowchart shown in FIG. 9, the host computer 49 stores only data whose phase information is 1 ° or more among the data sent from the control circuit 30 as valid data, and further stores the phase information in the designated position ( Coordinate point)
Is converted to a diameter of a circle (for example, converted to a value proportional to phase information), and the diameter is converted to a coordinate position based on the coordinate values in the X direction and the Y direction in an image memory (not shown). An image of a circle having the circle is drawn, and this is displayed on the display device 50.

Since the above process is repeated while data is transferred from the control circuit 30, when the input pen 10 is moved while changing the pen pressure, the diameter differs along the locus 60 of the coordinate points as shown in FIG. The images 61 of the circles are continuously arranged, and an image as if using a brush is obtained. Note that the obtained image can be hard-copied by the output device 51 if necessary, and FIG. 11A shows an example of the output result. Further, if the process of filling the inside of the circle is performed,
As shown in FIG. 11B, a more natural output result is obtained.

(Effect of the Invention) As described above, according to the present invention, the ferrite chip is displaced with respect to the end of the coil according to the displacement of the core,
Since the permeability of the coil changes according to the displacement amount, the inductance of the coil changes, and the tuning frequency of the tuning circuit formed by the coil and the capacitor changes, so that radio waves can be transmitted and received from the tablet. The change of the tuning frequency, that is, the information corresponding to the operation of the operator can be obtained by using the coordinate input device for performing the position detection by using a coordinate input device. It does not hinder the movement or breaks due to fatigue, and the change in the tuning frequency depends only on the displacement of the core body, so that the operation can be performed in any part of the tablet. You can get accurate information,
Since it is composed of only small and light parts such as a coil, a capacitor, a ferrite chip, etc., there are advantages such as not only that the above-mentioned cable is unnecessary but also that the operability at the time of input is very good.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the input pen of the present invention, FIG. 2 is a configuration diagram showing an example of a coordinate input device using the input pen of the present invention, and FIG. 3 is an X direction and a Y direction of the tablet. 4, FIG. 4 is a signal waveform diagram of each part in FIG. 2, FIG. 5 is a flowchart of processing in a control circuit, and FIGS. 6 (a), (b), and (c) are control circuits. 7 is a timing chart showing a basic coordinate detecting operation in FIG. 7, FIG. 7 is a diagram showing a detection voltage obtained from each loop coil at the time of the first coordinate detecting operation, and FIG. 8 is a coordinate detecting operation after the second time FIG. 9 is a flowchart of a process in the host computer, FIG. 10 is a diagram showing an image when the input pen is moved while changing the pen pressure, and FIG.
FIGS. 7A and 7B are diagrams illustrating an example of an output result. 10 Input pen, 12 Core, 13 Ferrite chip, 14 Coil, 17 Capacitor.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshihide Sento 5-23-4 Sakurada, Washinomiya-cho, Kitakatsushika-gun, Saitama Prefecture Inside Wacom Co., Ltd. (56) References JP-A-59-3537 (JP, A)

Claims (2)

(57) [Claims] 1. An input pen used in a coordinate input device for indicating a position to be measured to a tablet and notifying an operation of an operator, the input pen having a ferrite chip, and responding to the operation of the operator. A core which is continuously displaced in the pen axis direction and is held so as to be recoverable, a tuning circuit including a coil capable of slidably housing the core therein and a capacitor connected to the coil, The ferrite chip is arranged near the end of the coil, the tuning circuit tunes to a radio wave transmitted from the tablet, and notifies the tablet of a displacement of the core body due to an operation by a reflected radio wave to the tablet. Input pen of coordinate input device. 2. The input pen of a coordinate input device according to claim 1, wherein a pen pressure is used as an operation of an operator.