JPH02103676A - Handwriting collating device - Google Patents

Abstract

PURPOSE:To confirm the identity of a person by detecting the forms and the writing pressure of the characters signed on a coordinate input surface to decide whether the detected signature is equal or not to the handwriting of the person himself/herself that is previously registered. CONSTITUTION:The coordinate value of a position pointed on a coordinate input surface by a position pointing device is detected and at the same time the writing pressure applied to the coordinate input surface via the device 20 is also detected as another prescribed physical value. A handwriting deciding means consists of a host computer 49, a main storage 50, and a computing memory 51. Then the handwriting deciding means decides whether the characters signed on the coordinate input surface are coincident or not with the handwriting of the person himself/herself registered previously based on the detected coordinate value nd physical value of the device 20. Thus it is possible to obtain a handwriting collating device that can serve as a means which confirms the identity of a person.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a handwriting verification device that compares the handwriting of input signature characters with the handwriting of previously registered signature characters.

(Prior Art) This type of conventional handwriting verification device optically reads signature characters written on an input form to compare the shape with the characters of a signature registered in advance.

(Problem to be solved by the invention) However, when signing a signature on an input form, it is possible to write the shape of the character to resemble another person's handwriting, so it is possible to optically read the signature character and register it in advance. Conventional handwriting matching devices that perform shape matching with signature characters have not yet been put into practical use as a means of confirming the identity of a person.

SUMMARY OF THE INVENTION An object of the present invention is to provide a handwriting verification device that can eliminate the above-mentioned problems and can be used as a means for confirming the identity of a person.

(Means for Solving the Problems) In order to solve the above problems, the present invention includes means for detecting the pen pressure applied by the position indicator to the coordinate input surface as some other physical quantity. A handwriting matching device is constructed from a coordinate input device and a handwriting determination means for determining whether or not the handwriting is registered in advance of the person based on the coordinate values of the position indicator and the physical quantity detected by the coordinate input device. Configured.

Further, in claim (2), the coordinate input device in the handwriting verification device according to claim (1) is configured such that a large number of loop coils are
A tablet comprising a group of loop coils in the X direction arranged in parallel in the direction and a group of loop coils in the Y direction in which a large number of loop coils are arranged in parallel in the Y direction; a position indicator having a tuning circuit whose tuning frequency changes around a predetermined frequency;
X-direction selection means for sequentially selecting one loop coil from a group of loop coils in the X direction of the tablet; and Y-direction selection means for sequentially selecting one loop coil from a group of loop coils in the Y direction of the tablet; a signal generating means for generating an AC signal of the predetermined frequency; a signal detecting means for detecting the AC signal of the predetermined frequency; and each of the X direction and Y direction selected by the X direction and Y direction selection means. connection switching means for alternately connecting the signal generating means and the signal detecting means to the loop coils; It consists of coordinate detection means for determining the input coordinates in the X direction and Y direction using the indicator.

Further, in claim (3), in the handwriting verification device according to claim (2), the position indication is performed based on an AC signal detected by the signal detection means from one loop coil in the X direction or the Y direction. A change in the tuning frequency in the tuning circuit of the device was detected as a change in phase with respect to the predetermined frequency, and the change in phase was used as a physical quantity.

(Function) According to claim (1), the coordinate input device detects the coordinate values of the position indicated on the coordinate input surface by the position indicator, and detects the pen pressure applied to the coordinate input surface by the position indicator. is detected as some other physical quantity, and the handwriting determining means determines whether or not it is the handwriting of the person registered in advance, based on the coordinate values of the position indicator detected by the coordinate input device and the physical quantity. will be held.

According to claim (2), the signal generating means is connected to the - loop coil selected by the X-direction selection means from the X-direction loop coil group of the tablet through the connection switching means, and the signal generating means is connected to the loop coil of - selected by the X-direction selection means from the X-direction loop coil group of the tablet. When a signal is applied, a radio wave is generated from the one loop coil, and the radio wave excites the coil of the tuned circuit of the position indicator on the tablet, causing the tuned circuit to generate an induced voltage of the predetermined frequency.

Thereafter, when the signal generating means is disconnected from the first loop coil by the connection switching means and the signal detecting means is connected instead, radio waves are no longer generated from the first loop coil, but instead, the signal generating means is disconnected from the first loop coil. Radio waves are generated from the coil of the tuned circuit based on the generated induced voltage, and the radio waves reversely excite the first loop coil to generate an alternating current signal, that is, an induced voltage.

Transmission and reception of the radio waves is performed for all the loop coils in the X and Y directions by the X and Y direction selection means and the connection switching means, and the corresponding induced voltages are detected by the signal detection means. , the voltage value of the induced voltage is a value that depends on the distance between each loop coil and the coil of the tuned circuit, that is, the position indicator.
The input coordinates of the direction are calculated.

According to claim (3), the tuning frequency in the tuning circuit of the position indicator is changed based on the AC signal detected by the signal detection means from one loop coil in the X direction or the Y direction. It is detected as a change in phase with respect to the predetermined frequency, and writing pressure is detected based on the change in phase.

(Embodiment) FIG. 1 shows an embodiment of the handwriting verification device of the present invention, in which 10 is a tablet, 20 is a position indicator, 30 is a control circuit, 31 is a signal generation means (circuit), 32 and 33
is a selection means (circuit) for the X direction and the Y direction. Also,
34. 35 is a transmission/reception switching circuit, 36 is an XY switching circuit, 37
is a reception timing switching circuit, which constitutes connection switching means. Further, 38 is a bandpass filter (B P F
), which constitutes a signal detection means. Also, 39
is a wave detector, 40 is a low-pass filter (LPF),
These constitute a coordinate detection means including processing in a control circuit 30 which will be described later. Further, 41 and 42 are phase detectors (PSD), and 43 and 44 are low-pass filters (LPF), which together with the processing in the control circuit 30 described later constitute phase detection means. Further, 45 and 46 are drive circuits, 47° and 48 are amplifiers, 49 is a host computer, 50 is a main storage device, 51 is a memory for calculation, and 52 is a display device. The handwriting determination means includes a host computer 49. It is composed of a main storage device 50 and a calculation memory 51.

FIG. 2 shows details of the loop coil group 11 in the X direction and the loop coil group 12 in the Y direction, which constitute the tablet 10. The loop coil group 11 in the X direction includes a large number of coils arranged parallel to each other and overlapping each other along the X direction.
For example, 48 loop coils 11-1.11-2.・・・
... 11-48, and the Y-direction loop coil group 12 is a large number of 48 loop coils 1 arranged parallel to each other and overlapping each other along the Y direction.
2-1.12-2. . . . 12-48, and the loop coil group 11 in the X direction and the loop coil group 12 in the Y direction are closely overlapped with each other (however, in the drawing, they are separated for ease of understanding). ), and is housed in a case made of non-metallic material (not shown). Although each loop coil is configured with one turn here, it may be configured with multiple turns as necessary.

FIG. 3 shows the specific structure of the position indicator 20.
A pen barrel 21 made of a non-metallic material such as synthetic resin, a core body 23 having a ferrite chip 22, a coil 24 that can slidably accommodate the core body 23, and a rear end of the core body 23. The lead holder 25 to hold and the lead holder 25 to the pen barrel 2
1 and a capacitor 27. Like the core of a ballpoint pen, the core body 23 has ink built-in so that characters can be drawn on paper.

As shown in FIG. 1, the coil 24 and capacitor 27 are connected in series to form a well-known tuning circuit 28, and the inductance of the coil 24 and the capacitance of the capacitor 27 are determined by the tuning ( (resonance) frequency is set to a value that is approximately a predetermined frequency fO. Here, when the core body 23 is held by the core holder 25, the ferrite chip 22 is positioned at the end of the coil 24, and the position indicator 20 is used to mark the entry form fixed on the tablet 10. When signing, the core body 23, that is, the ferrite chip 22 moves according to the pressure of the pen at that time.
As a result, the inductance of the coil 24 changes, and the tuning frequency in the above-mentioned tuning circuit 28 changes slightly.

Next, the operation of the device will be explained together with its configuration.First, we will explain how radio waves are transmitted and received between the tablet 10 and the pen 20, and the signals obtained at this time.
This will be explained according to the diagram.

The control circuit 30 is composed of a well-known microprocessor or the like, and controls the signal generation circuit 31 and also controls the switching of each loop coil of the tablet 10 via the selection circuits 32 and 33 according to the flowchart shown in FIG. In addition, the XY switching circuit 36 and the reception timing circuit 37
The output values from the low-pass filters 40, 43, and 44 are converted into analog signals.
It performs digital (A/D) conversion, performs arithmetic processing to be described later to obtain the input coordinates from the position indicator 20, detects the phase of the received signal, and sends these signals to the host computer 49.
Send to.

The selection circuit 32 is for sequentially selecting one loop coil from the loop coil group 11 in the X direction, and the selection circuit 33 is for sequentially selecting one loop coil from the loop coil group 12 in the Y direction. Each of them operates according to 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 selected one loop coil in the Y direction to the drive circuit 45 and the amplifier 47. are alternately connected to a drive circuit 46 and an amplifier 48, and these operate according to a transmission/reception switching signal, which will be described later.

The signal generating circuit 31 has a predetermined frequency fO1, for example, 500k.
Hz rectangular wave signal A1 Signal B1 obtained by delaying the phase of the rectangular wave signal A by 90'' A predetermined frequency fk.

For example, a 15.625 kHz transmission/reception switching signal C and a reception timing signal are generated. The rectangular wave signal A is sent as it is to the phase detector 41, is converted into a sine wave signal E by a low-pass filter (not shown), and is further converted into a sine wave signal E.
The rectangular wave signal B is sent to either the drive circuit 45 or 46 via the Y switching circuit 36, and the rectangular wave signal B is sent to the phase detector 4.
2, and the transmission/reception switching signal C is sent to the transmission/reception switching circuit 3.
Furthermore, the reception timing signal is sent 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 drive circuit 45, converted to a balanced signal, and further The signal is sent to the transmission/reception switching circuit 34, but since the transmission/reception switching circuit 34 switches and connects either the drive circuit 45 or the amplifier 47 based on the transmission/reception switching signal C, the signal is output from the transmission/reception switching circuit 34 to the selection circuit 32. The signal F is a signal F that outputs or does not output a 500 kHz signal every 32 μSeC for a time T (−1/2 fk ).

The signal F is passed through the selection circuit 32 to the terminal X of the tablet 10.
One loop coil 11-i (i-1, 2, ·
...48), but the loop coil 11
-1 generates a radio wave based on the signal F.

At this time, when the position indicator 20 is held in a substantially upright state on the tablet 1O, that is, in a use state, the radio wave excites the coil 24 of the position indicator 20, and the tuning circuit 28 receives the signal F. A synchronized induced voltage G is generated.

Thereafter, when the loop coil 11-1 is switched to the amplifier 47 side as the signal F enters a no-signal period, that is, the reception period, the radio wave from the loop coil 11-1 immediately disappears, but the induced voltage G It gradually attenuates depending on the loss within the tuning circuit 28.

On the other hand, the current flowing through the tuning circuit 28 based on the induced voltage G causes the coil 24 to emit radio waves. Since the radio waves reversely excite the loop coil 11-1 connected to the amplifier 47, an induced voltage due to the radio waves from the coil 24 is generated in the loop coil 11-1. The induced voltage is sent from the transmission/reception switching circuit 34 to the amplifier 47 only during the reception period, is amplified, becomes a reception signal H, and is further sent to the reception timing switching circuit 37.

The reception timing switching circuit 37 receives either X-direction or Y-direction selection information, here X-direction selection information,
A reception timing signal R which is essentially an inverted signal of the transmission/reception switching signal C is input, and the reception signal H is output during the period when the signal is at the high (H) level, and the reception timing signal R is output when the signal is at the low (L) level. Since it does not output anything, its output is a signal! (substantially the same as received signal H) is obtained.

The signal I is sent to a bandpass filter 38, which is a ceramic filter having a natural frequency fO, and a signal J having an amplitude corresponding to the energy of the acid component at the frequency fO in the signal I. (Strictly speaking, in a state in which several signals I are input to the bandpass filter 38 and converged) are sent to the wave detector 39 and phase detectors 41 and 42.

The signal J input to the detector 39 is detected and rectified,
After being converted into a signal, it is converted by a low-pass filter 40 with a sufficiently low cutoff frequency into a DC signal having a voltage value corresponding to approximately 1/2 of the amplitude, for example, VX, and sent to the control circuit 30.

The voltage value Vx of the signal is a value dependent on the distance between the position indicator 20 and the loop coil 11-1, here a value approximately inversely proportional to the fourth power of the distance,
changes when the voltage value Vx is switched, so in the control circuit 30, the voltage value Vx obtained for each loop coil is converted into a digital value, and by performing arithmetic processing to be described later on these values, the position indicator 20 changes in the X direction. Input coordinates are determined. Note that the input coordinates in the Y direction by the position indicator 20 are also 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, and at this time, the signal J
Assuming that the phase of the square wave signal A almost matches that of the rectangular wave signal A, the phase detector 41 outputs a signal Ml (substantially the same as the signal) which is the positive inversion of the signal J, and the phase The detector 42 outputs a signal M2 having a symmetrical waveform on the positive and negative sides.

The signal M1 is passed through the same low-pass filter 43 as the signal J.
The signal M2 is converted into a DC signal Nl (substantially the same as the signal) having a voltage value corresponding to approximately 1/2 of the amplitude of Vx, and sent to the control circuit 30. It is converted into a DC signal N2 by the control circuit 3.
0, but here the signal M2 of the phase detector 42
Since the positive side and negative side components are the same, the voltage value of the output of the low-pass filter 44 is 0 [V].

In the control circuit 30, the output values of the low-pass filters 43 and 44,
Here, the signals N1 and N2 are converted into digital values, and the following digital values are used to perform the arithmetic processing of the following equation (1), and the signals applied to the phase detectors 41 and 42, here J and the rectangular wave signal A, are Find the phase difference θ with

θ--tan″″’ (VQ/VP)
-.---(1) However, vP indicates a digital value corresponding to the output of the low-pass 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 Nl is VX, but the voltage value of the signal N2 is 0 [V], that is, VQ-0, so the phase difference is θ-0°.

Incidentally, the phase of the signal J changes in accordance with the tuning frequency in the tuning circuit 28 of the position indicator 20. That is,
When the tuning frequency in the tuning circuit 28 matches the predetermined frequency fO, an induced voltage of the frequency fO is generated in the tuning circuit 28 during both the signal transmission period and the signal reception period, and
Since an induced current synchronized with this flows, the received signal H
The frequency and phase of (or I) match with the rectangular wave signal A, and the phase of the signal J also matches with the rectangular wave signal A.

On the other hand, if the tuned frequency in the tuned circuit 28 does not match the predetermined frequency fO, for example, if the frequency is slightly lower than the frequency fO, for example fl, the tuned circuit 28 receives an induced voltage of the frequency fO during the signal transmission period. However, at that time, an induced current with a phase lag flows through the tuned circuit 28, and an induced voltage of approximately frequency fl and an induced current synchronized with this flow during the signal reception period, so that the received signal H The frequency of (or I) is the square wave signal A
The frequency is slightly lower than that of , and its phase is also slightly delayed. As mentioned above, since the bandpass filter 38 has only the frequency fO as its frequency, a shift in the frequency of the input signal toward the lower side is outputted as a phase delay, and therefore, the phase of the signal J is is the received signal H
It is even later than (or ■).

Conversely, if the tuning frequency in the tuning circuit 28 is slightly higher than the predetermined frequency fo, for example f2,
During the signal transmission period, the tuning circuit 28 has a frequency fO
An induced voltage of f2 is generated, but at that time, an induced current with a phase lead flows through the tuning circuit 28, and an induced voltage of approximately frequency f2 and an induced current synchronized with this flow during the signal reception period. The frequency of the received signal H (or I) is slightly higher than the frequency of the rectangular wave signal A, and its phase is also slightly advanced. bandpass filter 38
, the frequency shift toward the higher side of the input signal is
Contrary to the case described above, the signal J will be output as a phase lead, and therefore the phase of the signal J will be the same as that of the received signal H (or
) is even more advanced.

As described above, since the tuning frequency of the tuning circuit 28 changes depending on the writing pressure applied to the position indicator 20, the phase difference θ determined by the equation (1) also changes corresponding to the writing pressure. In this embodiment, the phase difference θ is set in advance so that when no pen pressure is applied to the position indicator 20, the phase difference θ is about 160″, and when the most pen pressure is applied, it is about 60°.

The water-filled phase difference θ is, for example, added by 40” so that it becomes 00 when the tip of the core 23 of the position indicator 20 is in slight contact with the surface of the tablet 1o, and the difference is -20° to 1
The phase information is converted into phase information with a value in the range of 00°, and is sent to the host computer 49 together with coordinate values in the X and Y directions at predetermined intervals (note that the above-mentioned addition of 40° is performed on the host computer 49 side. ).

Next, the coordinate detection operation, the phase detection operation, and the manner in which handwriting is compared will be described in detail with reference to FIGS. 5 to 9.

First, when the entire device is powered on and enters the measurement start state, the control circuit 30 sends information for selecting the X direction to the XY switching circuit 36 and reception timing switching circuit 37, and also sends information to the X direction loop coil of the tablet 10. 11-1
~11-48, information for selecting the first loop coil 11-1 is sent to the selection circuit 32, and the loop coil 11
-1 is connected to the transmission/reception switching circuit 34.

The transmission/reception switching circuit 34 switches the loop coil 11-1 to the drive circuit 45 and the amplifier 4 based on the transmission/reception switching signal C mentioned above.
7 alternately, but in this case, the drive circuit 45 is connected to 32μ
sec, 16 sine wave signals of 500kHz as shown in FIG. 6(a) are transmitted to the loop coil 1.
1-1 (In addition, in FIG. 4, only five of them are shown for convenience of the drawing.)

The switching between transmission and reception is repeated seven times for one loop coil, here 11-1, as shown in FIG. 6(b). These seven transmission and reception repetition periods correspond to one loop coil selection period (448 μsec).

At this time, an induced voltage is obtained at the output of the amplifier 47 for one loop coil every seven reception periods, but this induced voltage is passed through the reception timing switching circuit 37 to the bandpass filter 38 as described above. It is sent out, averaged, and sent to detector 3.
9. Phase detector 41, 42 and low pass filter 40, 43
．． The signal is sent to the control circuit 30 via 44.

The control circuit 30 converts the output value of the low-pass filter 4o into an A/D converter.
Convert and manually install position indicator 2o and loop coil 11-
1, and is temporarily stored as a detected voltage, for example, Vxl.

Next, the control circuit 30 sends information for selecting the loop coil 11-2 to the selection circuit 32, connects the loop coil 11-2 to the transmission/reception switching circuit 34, and connects the position indicator 20 and the loop coil 11-2. A detection voltage Vx2 proportional to the distance is obtained and stored, and thereafter the loop coils 11-3 to 11-1 are
1-48 are sequentially connected to the transmission/reception switching circuit 34, and as shown in FIG.
Detection voltage Vxl-Vx48 proportional to the distance in the X direction from the position indicator 20 for each loop coil as shown in C)
(However, only a part of it is shown in an analog representation in FIG. 6(C).)

The actual detected voltage is determined by the position indicator 20 as shown in FIG.
It is obtained only in several loop coils before and after the position (xp) where xp is placed as the center.

The control circuit 30 checks whether the voltage value of the stored detection voltage is above a certain detection level, and if it is below the certain detection level, selects each loop coil in the X direction and performs voltage detection again. Repeatedly, if the detection level is above a certain level, proceed to the next process.

Next, the control circuit 30 sends selection information in the X direction to the XY switching circuit 36 and the reception timing switching circuit 37, and switches the selection circuit 33 and the transmission/reception switching circuit 35 in the same manner as described above.
The output value of the low-pass filter 40 when transmitting and receiving radio waves is A/
The detection voltage depending on the distance between the position indicator 20 and each of the loop coils 12-1 to 12-48 in the X direction obtained by D conversion is temporarily stored. After this, a level check is performed in the same manner as above, and if it is below a certain detection level, the process returns to selection of each loop coil in the X direction and voltage detection again, and
If it is above a certain detection level, the X-direction and X-direction coordinate values of the position indicator 20 are calculated from the stored voltage value as described later.

Next, the control circuit 30 controls the loop coil 11- in the X direction.
1 to 1l-48 (or X direction loop coil 12-1 to
12-48), the selection circuit 32 receives information for selecting the loop coil (peak coil) from which the maximum detected voltage was obtained.
(or 33), and the transmission and reception of the radio waves is repeated multiple times, for example, 7 times, and at that time, the low-pass filters 43 and 44
The output value obtained is A/D converted, and the phase difference θ is calculated as described above.

The phase difference θ is added by 40 degrees, converted into phase information, and transferred to the host computer 49 at predetermined time intervals together with the X-direction and X-direction coordinate values of the position indicator 20, and stored in the calculation memory 51. be done.

When the first coordinate detection operation and phase detection operation are completed in this way, the control circuit 30 performs the second and subsequent coordinate detection operations as shown in FIG. Out of 11-48, information for selecting only a certain number of loop coils, for example, 10 loop coils before and after the loop coil from which the maximum detected voltage was obtained, is sent to the selection circuit 32, and Loop coil 12
-1 to 12-48, centering on the loop coil where the maximum detection voltage was obtained, a certain number of 1
Information selection circuit 33 for selecting only 0 loop coils
The output value is obtained in the same manner as described above, and the position indicator 20
The X-direction and X-direction coordinate detection operations and phase detection operations are performed, and the obtained coordinate values and phase information are transferred to the host computer 49, and these steps are repeated hereafter.

To explain the level check mentioned above in detail, it checks whether the maximum value of the detection voltage has reached the detection level and which loop coil has the maximum detection voltage, and then checks whether the maximum value of the detection voltage has reached the detection level. If it has not been reached, subsequent coordinate calculations etc. are stopped, and the center of the loop coil to be selected in the next coordinate detection operation and phase detection operation is set.

As one calculation method for determining the X direction or the coordinate value in the X direction, for example, the coordinate value xp, the detection voltages Vxl to V
There is a method of approximating the waveform near the maximum value of x4B by an appropriate function and finding the coordinates of the maximum value of the function.

For example, in FIG. 6(c), the maximum detection voltage Vx3
By approximating the detection voltages VX2 and Vx4 on both sides thereof by a quadratic function, it can be calculated as follows (however, the coordinate values of the center positions of each loop coil 11-1 to 11-48 are x48, and the interval is ΔX.)
. First, from each voltage and coordinate value, Vx2= a (x2- xp) 2+ b
...--<2)Vx3-a(x3-xp) +
b -------(3) Vx4=a(x4-
xp) +b - (4). Here, a and b are constants (a<O) and x3-x2ΔX...(5
)x4−x2 m2Δx −−−−−
−(8), converting equations (5) and (6) to (3) and (4)
By substituting it into the formula and arranging it, we get xp-x2+Δx/2 ((3Vx2-4Vx3+
VX4) / (VX2-2 Vx3+ Vx4) )
・・・・・・(7)

Therefore, from each detection voltage VXI to V The coordinate value xp of the position indicator 20 can be calculated by performing an operation corresponding to the above-mentioned equation (7) from the coordinate value (known) of the previous loop coil.

On the other hand, the host computer 49 stores the data transferred from the control circuit 30 in the calculation memory 51 and compares it with the registered data stored in the main storage device 50.

Next, the operation when registering handwriting data will be explained based on the flowchart shown in FIG.

Now, the case of registering and verifying the signature in the "patent bold section" shown in FIG. 10 will be explained as an example.

The host computer 49 stores the above-mentioned data transferred from the control circuit 30 in the calculation memory 51 (S2), and determines whether the signature is completed (S2).
S3). In this embodiment, information for signing termination is input using a switch provided in the host computer 49. As a result of this determination, if the signature is not completed, the process moves to sl, and if the signature is completed, the name is recognized as a character stamp from the data stored in the calculation memory 51 (S
4). Next, the data between the data at the signature start point A and the data at the signature end point B shown in FIG.
As shown in FIG. 1, n data DI-D ports are sampled (S5). Using the sampling data D1 to Dn, the width X1 in the X direction and the width Y1 in the Y direction of the signature shown in FIG. 10 are calculated (S6) (S7). Next, the coordinates of the center point P of the signature are calculated (S8), and the distances 11 to 1n between the coordinates of the point P and the coordinates of each of the sampling data D1 to Dn are calculated (S9). Furthermore, calculate the average value of these distances 11-In. S10) Use this average value to normalize the distances 11-1n and calculate 1-Ln (S11). As a result, as shown in FIG. 12, the movement of the tip of the core body 23 of the position indicator 20 can be obtained as a value normalized by the distance from the point P in FIG. 10. Next, the sampling data D1 to Dn and the standardized information L1 to Ln are stored as handwriting data in the main storage device 50 together with the name and last name recognized by the character stamp (S12). Through the above operations, the handwriting data of the signature by the person is registered.

Next, the operation when verifying the handwriting of a signature will be explained based on the flowchart shown in FIG.

The host computer 49 stores the data transferred from the control circuit 30 in the calculation memory 51.
) (SF3), it is determined whether the signature is completed (SPB). In this embodiment, information for signing termination is input using a switch provided in the host computer 49. As a result of this determination, if the signature has not been completed, the process shifts to SPI processing, and if the signature has been completed, the calculation memory 51
Names and names are recognized as character stamps from the data stored in (SF3). Next, the name registered in the main storage device 50 is searched (5P5), and it is determined whether a name corresponding to the input name is registered (SPB). As a result of this determination, if the input name is not registered, the display device 52 displays that it is unregistered (SF3
), as a result of the SPB judgment, if the last name corresponding to the manually inputted name is registered, the input data stored in the calculation memory 51 is used to calculate the data of the signature start point Ac and the signature end point Be. n pieces of data Dcl to Den are sampled at equal time intervals from the data between the data (S
Pli). Width Xcl in the X direction and width Y in the Y direction of the signature input using the sampling data Dcl to Den
Calculate et (SF3) (SPIO). Next, calculate the coordinates of the center point Pc of the signature (SpH), and calculate the distances let~lcn between the coordinates of the point Pc and the coordinates of each of the sampling data Dcl~Den (SP12).
). Furthermore, calculate the average value of these distances 1cl to lcn (5P13), and use this average value to normalize the distances 1cl to 1cn to calculate the value L cl - L cn (SF14
), then the phase information θ of the input data D el-D Cn
Compare c1 to θCn and the normalized information LC1 to Len in correspondence with the phase information θl to θn and normalized information LL-Ln of the registered handwriting data (S P 15
). The comparison method at this time is, for example, to find the difference between each of n values of the phase information and normalization information of the registered handwriting data and the handwriting data based on the input data,
Furthermore, the average value of the absolute values of this difference is calculated, and when the calculated average value is smaller than the reference value, it is assumed that they match. Next, based on the comparison result in 5P14, it is determined whether or not the handwritings match (5P1B), and if they do not match, a message indicating that the handwritings do not match is displayed on the display device 52.
P17) When the handwriting matches, the display device 52 displays that the handwriting matches.

Note that the number of loop coils and the arrangement thereof in the embodiments are merely examples, and it goes without saying that the present invention is not limited thereto.

Further, in this embodiment, the inductance of the coil 24 is changed, but the same effect can be obtained by changing the capacitance of the capacitor 27.

Further, in the present embodiment, a form is fixed to the tablet 10 and the signature is written, but the tablet 10 may be provided with a display device 52 and the signed characters may be displayed on the display device 52.

Further, the method of comparison using writing pressure in the embodiment is just one example, and it goes without saying that the method is not limited to this.

Furthermore, in this embodiment, the pen pressure is detected as a change in the tuning frequency of the tuning circuit of the position indicator as a change in phase with respect to a predetermined frequency, but the invention is not limited to this. Similar effects can be obtained by detecting physical quantities such as light brightness, voltage, current, magnetic flux density, and ultrasonic frequency.

(Effects of the Invention) As explained above, according to claim (1), there is provided a coordinate input device having a means for detecting a pen pressure applied to a coordinate input surface by a position indicator as some other physical quantity, and the coordinate input device. The handwriting verification device is configured with a handwriting determination means that determines whether or not the handwriting of the person registered in advance is based on the coordinate values of the position indicator and the physical quantity detected by the user. Since it is possible to detect the shape and writing pressure of the written character, it is possible to determine whether or not the handwriting is the handwriting of the person registered in advance.

According to claim (2), in addition to the above-mentioned effects, the tuning circuit of the position indicator has a coil and a capacitor as main components, and does not require cables or the like. It does not require heavy parts such as magnets, and therefore has good operability during input, allowing characters to be drawn in the same way as normal.

Further, according to claim (3), since the coordinate values and pen pressure that change over time are detected using changes in the tuning frequency in the tuning circuit of the position indicator, the position indicator can be used to display the tablet on the tablet. Because the characters are read when you draw them, it becomes difficult to intentionally draw characters with similar shapes, stroke order, and pressure. Therefore, it is possible to confirm the identity of the person by comparing the handwriting of the signature.

Further, by widely disseminating the handwriting matching device of the present invention, there are advantages such as eliminating the need to carry a credit card or the like and making it possible to prevent a lost credit card or the like from being misused.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the handwriting verification device of the present invention, Fig. 2 is a detailed block diagram of the loop coil group in the X direction and Y direction of the tablet, and Fig. 3 is a cross-sectional view of the position indicator. , Fig. 4 is a signal waveform diagram of each part in Fig. 1, Fig. 5 is a flowchart of processing in the control circuit, and Fig. 6 (a), (b), and (c) shows basic coordinate detection operations in the control circuit. A timing diagram, FIG. 7 is a diagram showing the detection voltage obtained from each loop coil during the first coordinate detection operation, and FIG. 8 is a timing diagram showing the second and subsequent coordinate detection operations and phase detection operation. FIG. 9 is a flowchart of handwriting data registration processing in the host computer of one embodiment, FIG. 10 is a diagram showing an example of a signature drawn on a tablet, FIG. 11 is a diagram showing an example of sampling data in one embodiment, 1st
FIG. 2 is a diagram showing the relationship between time and normalization information in one embodiment, and FIG. 13 is a flowchart of handwriting data matching processing in the host computer of one embodiment. 10...Tablet, 11...X-direction loop coil group, 12...Y-direction loop coil group, 20...
Position indicator, 24... Coil, 27... Capacitor, 28... Tuning circuit, 30... Control circuit, 31...
・Signal generation circuit, 32...X direction selection circuit, 33.
... Y direction selection circuit, 34.35... Transmission/reception switching circuit, 36... XY switching circuit, 37... Reception timing switching circuit, 38... Bandpass filter, 39... Detector, 40 .43.44...Low pass filter, 41.42.
・・Phase detector, -49 ・・Host computer, 5
0...Main storage device, 51...Memory required for calculation, 52.
...Display device.

Claims (3)

[Claims] (1) A coordinate input device having a means for detecting the pen pressure applied by a position indicator to a coordinate input surface as some other physical quantity, and a coordinate value of the position indicator detected by the coordinate input device and the physical quantity. 1. A handwriting verification device comprising: handwriting determining means for determining whether or not the handwriting is the handwriting of a pre-registered person based on the handwriting of the person. (2) The coordinate input device is a tablet consisting of a group of loop coils in the X direction, which is made up of a large number of loop coils arranged in parallel in the X direction, and a group of loop coils in the Y direction, which is made up of a large number of loop coils arranged in parallel in the Y direction. and a position indicator having a tuning circuit that includes at least a coil and a capacitor and whose tuning frequency changes around a predetermined frequency in response to pen pressure; and one loop coil in the X-direction loop coil group of the tablet. X-direction selection means for selecting; Y-direction selection means for sequentially selecting one loop coil from a group of loop coils in the Y-direction of the tablet; signal generation means for generating the alternating current signal of the predetermined frequency; A signal detection means for detecting an alternating current signal of a predetermined frequency, and the signal generation means and the signal detection means are alternately connected to each loop coil in the X direction and Y direction selected by the X direction and Y direction selection means. connection switching means for connecting; and coordinate detection means for determining input coordinates in the X and Y directions by the position indicator based on AC signals detected by the signal detection means from each of the loop coils in the X and Y directions. A handwriting verification device according to claim (1), comprising: (3) Based on the AC signal detected by the signal detection means from the one loop coil in the X direction or Y direction,
The handwriting matching device according to claim 2, wherein a change in the tuning frequency in the tuning circuit of the position pointing device is detected as a change in phase with respect to the predetermined frequency, and the change in phase is used as a physical quantity.