JPS58115588A - Coordinate reader - Google Patents

Abstract

PURPOSE:To read coordinates with a high precision, by providing a counter for fundamental wave and a counter for higher harmonic and indicating the phase difference of the fundamental wave and the phase difference of the higher harmonic with counted values and performing the synthesizing processing of them to output coordinate data of a position indicated by a pen. CONSTITUTION:A counter 11 for fundamental wave and a counter 12 for higher harmonic start to count up high-speed clocks clk by control signals g1 and g2 from a controlling part 17 and stop to count them by a fundamental wave signal detl and a higher harmonic detection signal det 2 which are obtained when a position on a tablet is indicated by the pen. High-speed clocks clk are generated in the controlling part 17 on a basis of clocks from a signal generating part and are applied to counters 11 and 12. Counted values of counters 11 and 12 are synthesized 15 through buffer registers 13 and 14 and are outputted as coordinate data of the position, which is indicated by the pen, from an output buffer 16.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coordinate reading device using magnetic field coupling that can read the coordinates of a designated position with high precision.

Locus IIIAfl using magnetic field coupling! The basic structure of the detection device has already been proposed.The tablet is equipped with multiple coils, each coil is excited by sequentially shifting the phase of each coil, and when a pen with a detection coil is directed on the tablet, The coordinates of the indicated position can be read based on the phase of the signal induced in the detection coil.

FIG. 1 is a block diagram of the coordinate reading device described above. The tablet 1 is composed of a plurality of coils 1", 1!/ arranged orthogonally, and the pen 2 is composed of coils 1g, 1y.
It has a detection coil 2a that detects the magnetic field caused by the excitation of the magnetic field.

The signal induced in this detection coil 28 is added to the amplification section 5 having an amplifier and a filter. The signal generating section 4 applies a clock and a tie-setting signal for each predetermined period of this clock to the signal processing section 6, and also applies a plurality of signals having sequentially different phases to the switching driving section 5. For example, if the number of signals is 100, the signals will have a phase difference of every 3.6°.

The switching drive unit 5 has an X-Y coil 1y and a Y-Y coil 1y.
It switches the excitation between the two coils and supplies each coil with a drive current having a phase according to the signal from the signal generator 4. Therefore, a moving magnetic field in the X or Y direction is generated on the tablet 1.

In this case, when the drive current is a rectangular wave current, a moving magnetic field of a fundamental wave and harmonics is generated.

Figure 2 shows the phase change of the magnetic field in the X direction or Y direction on the tablet 1. If the phase of the fundamental wave magnetic field is curve G, then the phase curve of the duck-order harmonic magnetic field is as shown above. Otherwise, the fundamental wave region is divided into n regions. Therefore, when a drive current is sequentially supplied from the switching drive unit 5 to the coil 1z of FiX 1411 of the tablet 1, the detection coil 2a of the pen 2 receives a fundamental wave of a phase corresponding to the indicated position with respect to the reference phase. component and a harmonic component are induced, the fundamental component phase identifies a designated region, and the harmonic component identifies a position within the designated region. In other words, since the phase change of the harmonic magnetic field is larger than the phase change of the fundamental wave magnetic field per unit length, using only the fundamental wave component, the phase difference between the reference signal phase and the detection signal phase is
It is possible to remove threads with higher precision than when reading the coordinates of the position indicated by the pen 2.

The signal processing section 6 identifies the above-mentioned phase difference by analog processing or digital processing and outputs coordinate data XD and YD. When performing digital processing, for example, a fundamental wave counter and a harmonic counter are provided, and a control signal is used to start counting the high-speed clock, and a detection signal from Ben 2 is used to stop the sicant. Since the contents of the count indicate the phase difference of the fundamental wave and the phase difference of the higher logic waves, the coordinate data of Ben 2's indicated position is outputted by combining them.

It is possible to provide two detection coils 28, one for the fundamental wave and one for the harmonics, but it is also possible to use one for both purposes. In that case, the fundamental wave detection signal and the harmonics are The signal is separated into a detection signal and applied to the signal processing section 6. When the indicated position of Shiben 2 is determined by the harmonic detection signal, as can be seen from Figure 2, it only indicates the position within each area, so it can be determined which area it is by the fundamental wave detection signal. It is for identification.

For example, when using a fundamental wave counter of '5yyy' and a fourth harmonic counter of 'FFF' in hexadecimal notation, the count will be as shown in Figure S. When the indicated position is point A, If the fundamental wave counter shows #16j2" and the harmonic counter shows '6AF', '16A2°
The upper digits of '6AF' are used as area identification data, '6AF' is combined as position data, and the combined data, that is, coordinate data, is '6AF'.
16AF''.

However, if point B near the boundary of the harmonic region is designated, the following two sets of combined data may be obtained. That is, when the harmonic counter indicates C005°,
If the fundamental wave counter is #2FF4'' and 9, the composite data will be '2005'.

Also, due to the error in the fundamental wave detection No. 1g, the fundamental wave counter is
300B", the composite data is '5005'.
", and the difference is tt by an area corresponding to one period of the harmonic. Such an error occurs near the boundary of the area caused by high-grade waves.

The present invention eliminates the above-mentioned errors by simple means,
The purpose is to perform highly accurate coordinate reading. Examples will be described in detail below.

FIG. 4 is an explanatory diagram of the principle of the embodiment of the present invention. When the count contents of the harmonic counter are "dooo" to "400" and "coo" to "FFF", 'soo' is used as offset data to generate the harmonic wave. After adding or subtracting the count contents of the counter and the count contents of the fundamental wave phase counter, the offset data C8 is obtained from the combined data.
0, which is the subtraction or addition of 00.
The area of the tablet corresponding to the 8th period is divided into L1 to L5, and the area near the area boundary is L1. When LS is instructed, offset data is added or subtracted, then synthesized, and offset data is subtracted or added from the synthesized data.

For example, when you specify 0 point, the harmonic counter will be '01'.
0" and the fundamental wave counter is '0FFF', '010' + '800' = '810' and #
QFFF" + σ800' = '177F' is combined after adding the offset data, so the combined data becomes #1810°, and when subtracting the offset data, '1810' - '800' = '1010'. C8
, this becomes the output data. Also, the fundamental wave counter is '1'
005", '1005"+#800
"W'1805" and composite data d '1810'
Therefore, the output data is '1010'.

The above-described addition or subtraction of the offset data can be performed by a microprocessor-based calculation means, but it can also be easily realized by changing the count start timing of the fundamental wave counter and the harmonic counter by 11114%. That is, if the count contents of the fundamental wave counter and the harmonic counter shown by the solid line in FIG. 4 are made as shown by the chain line, this corresponds to the case where the offset data #800'' is added.Subtraction is carried out in the regular manner. In this case, the count content characteristics may be shifted to the right.

FIG. 5 is a block diagram of main parts of an embodiment of the present invention, 1
1 is a fundamental wave counter, 12 is a harmonic counter, 13
．． 14 is a buffer register, 15 is an adder, 16 is an output buffer, and 17 is a control section.

The fundamental wave counter 11 and the harmonic counter 12 are operated by the high speed clock c by the control signal Q142 from the control section 17.
Fundamental wave detection signal dat1 obtained by starting lLk count-up and pointing on the tablet with a pen
and harmonic detection signal dat2, the high-speed clock
(see figure) and spread directly from the signal generator.
The control section 17-3 generates the signal based on K and adds it to each counter 11.12.

When the fundamental wave network wave number is 4 KHz and the harmonic frequency is 16 KHz, the control signal g2 is added to the harmonic counter 12 every 174 cycles of the control signal g1 added to the fundamental wave counter 11. These control signals fLI92 are as shown in (a) and (&) in FIG. 6, and the count contents of the fundamental wave counter 11 and harmonic counter 12 are as shown in (-) and φ in FIG. 6. .

Detection signal dat1. The count content of the harmonic counter 12 when dat2 is added is added to the control unit 17, and the count contents of the harmonic counter 12 when dat2 is added are added to the control unit 17, and as described above ('000' to #400" and 1C00"
It is identified whether it is within the range of ~'FFF', and if it is not within this range, the offset data of #000"
In addition, when it is within the above range, the offset data ofa is set to '-800', and the control signal g1.g20 phase is added to the adder 15 by 172 cycles of the harmonic component.
Ru. That is, the control signal gL92 is set to the phase shown in FIG. 6(c) (φ).

As a result, the count contents of the fundamental wave counter 11 and the harmonic phase counter 12 become as shown in Figure 6) and (~).In other words, "800" is added to the count contents by the first control signal Q1+92. .

The adder 15 receives data from the upper bits of the fundamental wave phase counter 11 set in the buffer register 15, all bits of the harmonic counter 12 set in the phase register 14, and offset data ofa from the control unit 17. are added based on the command from the control s17, and the control tg number Q1. When the phase of Q2 is advanced, the offset data ofa becomes "-800", so it becomes correct coordinate data and is outputted via the output buffer 16.

Also control fl! If the 1/2 period phase of the harmonic is delayed in the number gL (72), this corresponds to the case where the count contents of the fundamental wave counter 11 and the harmonic counter 12 are set to '-800', so the control unit 17 offset data o
ft can be set to '800'.

The control unit 17 identifies whether the count content of the harmonic counter 12 is within a predetermined range and sends a control signal g11g2.
Since the switching of the 0 phase and the switching of the offset data oft is performed, it can be easily constructed using a normal logic circuit. Note that it is also possible to configure the system using a microprocessor and to identify and control the count contents of the harmonic counter 12 using program control. In that case, since it has an arithmetic function, it can be replaced by the adder 15.

As explained above, Fujusha uses a pen to detect the fundamental and harmonic moving magnetic fields on the tablet, and reads the coordinates of the position indicated by the shifter based on the relationship with the reference phase. A means such as the control unit 17 for identifying whether or not a range near the boundary of the divided area of the tablet, for example, Ll and LS in FIG. means for adding or subtracting offset data to and combining the area identification data obtained based on the detection signal and the position data within the area obtained based on the harmonic detection signal; Since it is provided with means such as an adder 15 for subtracting or adding offset data to the data obtained and outputting seated image data,
Because the phase change per focal length of the fundamental wave magnetic field is relatively small, even if there is an error in the area identification data based on the fundamental wave detection signal, the output coordinate data will be correct. Highly accurate coordinate reading becomes possible.

[Brief explanation of the drawing]

Figure 1 is a block diagram of the previously proposed coordinate reading device using magnetic field coupling, Figure 2 is an explanatory diagram of the magnetic field phase on the tablet, and Figure 5 is a diagram of the fundamental wave counter and harmonic phase counter. An explanatory diagram of the count contents, Figure 4 is the principle of the present invention! 52
Figure 5 is a block diagram of an embodiment of the present invention, and Figure 6 is an explanatory diagram of the operation. 1 is a tablet, 1s, 1ν is a coil, 2 is a pen, 2a
is a detection coil, 3 is an amplification section, 4 is a signal generation section, 5 is a switching drive section, 6 is an fg processing section, 11 is a fundamental wave counter,
12 is a harmonic power counter %1!1.14 is a buffer register, 15 is an adder, 16 is an output buffer, and 17 is a control section. Patent applicant Fujitsu Ltd. agent Patent attorney Gobe Tamamushi and 6 others 15 Zane

Claims (1)

[Claims] A tablet in which a plurality of coils are arranged, drive currents each having a specific phase are supplied to the plurality of coils in order to generate a moving magnetic field of a fundamental wave and harmonics, a position on the tablet is indicated, and the position is a signal processing unit that outputs coordinate data of a designated position based on the detection signal of the pen and the reference phase of the fundamental wave and harmonics; for a plurality of regions of the tablet divided according to the order of the harmonics, the identification data of the multi-region is determined based on the detection signal of the fundamental wave, and the identification data of the multi-region is determined based on the detection signal of the harmonics. In a coordinate reading device that obtains position data within and combines the identification data and the position data to obtain the coordinate data, is the position indicated by the pen on the tablet within a range near the boundary of the area? means for identifying whether or not the region is within a range near the boundary of the region; and when the means identifies that it is within a range near the boundary of the region, adding or subtracting offset data to the identification data of the region and the position data within the region and composing them. and means for subtracting or adding the offset data to the data synthesized by the coughing means to obtain the coordinate data.