JP2012220974A - Signature pad - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a signature pad which acquires feature information based on a position of a pen by performing detection of reflected light and processing, to verify authenticity of a signature.SOLUTION: A signature feature capturing device used for a signature pad comprises: a detection unit 200 for performing detection of reflected light; and a processing unit 300 for performing processing based on a detection result by the detection unit 200. When a user signs with a writing instrument OB in a detection area along a target surface 20, a light reception unit RU receives reflected light LR which is light LT radiated from an irradiation unit EU reflects when it meets the writing instrument OB. Based on a light reception result, the device detects movements of the writing instrument OB to determine authenticity of a signature.

Description

  The present invention relates to a signature pad for identifying authenticity such as a signature.

Conventionally, as disclosed in US Pat. No. 5,123,064 (Patent Document 2), US Pat. No. 5,448,044 (Patent Document 3), etc., many electronic signature authentication devices called signature pads have been sold by various companies.
Patent Document 1 provides a technique for performing signature authentication with higher accuracy by comparing not only the entire image of a signed handwriting but also the characteristics of the writing process.

Japanese Patent Laid-Open No. 10-11574 US Pat. No. 5,123,064 US Pat. No. 5,448,044

However, since the signature authentication apparatus disclosed in Patent Document 1 detects a handwriting vector, a writing pressure, a pen holding inclination angle, and the like, it does not use a dedicated pen in which a CCD area sensor, a pressure sensor, or the like is built in the authentication pen. must not.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a signature pad that can read signer-specific information for each signer even when signing with an arbitrary pen (writing tool) without the need for a dedicated pen. is there.

(1)
One aspect of the present invention is a signature pad, a flat plate portion having a flat surface portion, an irradiation portion that emits irradiation light, a light receiving portion that receives reflected light due to reflection of the irradiation light by an object, Based on the light reception result of the light receiving unit, a detection unit for detecting information for detecting the position of the object, a profile data recording unit for arranging the position detection information in time series and recording as profile data, a specific data A database that stores reference data in which information is arranged in time series, and a data collating unit that collates the profile data with the reference data are provided.
According to the above configuration, when a signature is made using an object as a writing tool, data related to the handwriting of the person who performs the signature can be obtained by detecting the position detection information of the writing tool. The authenticity of the signature can be verified based on the data.

(2)
Further, according to one aspect of the present invention, when the detection unit detects that the object has entered a predetermined space in contact with the planar portion, the profile data acquisition start process starts recording the position detection information. And, when the detection unit detects that the object has left the predetermined space, a profile data capture end process for ending the position detection information recording, and following the profile data capture end process The data collating unit collates the profile data with the reference data.
According to the above configuration, the profile data reading start process and the profile data reading end process are automatically performed, so that the processing time required for data acquisition can be minimized.

(3)
In addition, one embodiment of the present invention is characterized in that the irradiation light is infrared rays.
With the above configuration, it is possible to reduce the influence of ambient light during data capture and to detect position detection information with high accuracy.

(4)
Another embodiment of the present invention includes a clip portion that sandwiches a sheet-like medium in a part of the flat plate portion of the signature pad.
According to the above configuration, since the paper on which the actual signature is written can be fixed to the signature pad, the workability of the signature work is improved.

The block diagram which shows the basic composition of the signature pad of this embodiment. The block diagram which further subdivided the block diagram of FIG. 3 is a configuration example of a signature feature capturing device that can be used in the present embodiment. The structural example of a light-receiving part. 5A and 5B are configuration examples of the light receiving unit. The structural example of an irradiation part. 7A and 7B are diagrams illustrating a coordinate information detection method. 8A and 8B show signal waveform examples of the light emission control signal. The other example of a structure of an irradiation part. The structural example of a light-receiving part. FIG. 2 is an overview diagram of a signature pad according to an embodiment. The figure explaining a detection start by providing a detection area. Signal waveform example of authentication factor.

  Hereinafter, this embodiment will be described. In addition, this embodiment demonstrated below does not unduly limit the content of this invention described in the claim. In addition, all the configurations described in the present embodiment are not necessarily essential configuration requirements of the present invention.

  FIG. 1 is a block diagram showing a basic configuration of a signature pad according to an embodiment of the present invention. This signature pad has a signature feature capture device 1. The signature feature capturing device 1 includes an optical position detection device 100, and the optical position detection device 100 can detect signal data (position detection information) used for position detection of the writing instrument OB. By processing this position detection information by various calculations, the position of the writing instrument OB, for example, a position on a predetermined XYZ coordinate can be detected.

The position detection information obtained by the signature feature capturing device 1 is sent to an authentication factor extraction unit 2 that extracts an authentication factor for authentication of handwriting data, and the authentication factor extraction unit 2 extracts various authentication factors. Then, they are arranged and arranged (normalized) in time series, thereby generating profile data that is a characteristic unique to the signer (2f).
The profile data normalized by the authentication factor extraction unit 2 is sent to the reference data registration unit 3, where feature data is extracted and reference data is generated.
The reference data registration unit 3 generates reference data of a plurality of signers (3a), and these are indexed for each signer and stored in the database 4.

On the other hand, the profile data normalized by the authentication factor extraction unit 2 has a path to be sent to the data collation unit 5 in addition to the reference data registration unit. A reference data query that calls the reference data with the unique index is compared, and the reference data is compared with the profile data. Whether the reference data and the profile data have the same characteristics or not Identification, that is, verification is performed. If they have the same feature, the signature is true. If they do not have the same feature, the signature is determined to be false. The process for performing this authentication is called an authentication mode.
The true / false result is output via an API (Application Program Interface) 6.

  Here, the authentication factor is various pieces of information calculated based on the position detection information obtained by the optical position detection device 100. Specifically, the movement of the pen tip that is a handwriting, the tilt of the pen, It is speed data.

  FIG. 2 is a block diagram in which the apparatus of FIG. 1 is subdivided based on functions. The pen position is taken in time series by taking the pen movement information (1a). The pen movement information undergoes pen position analysis (2a), and performs pen tip locus extraction (2c) and pen tilt extraction (2d). Further, the pen movement information is subjected to pen speed analysis (2b), and pen speed extraction (2e) is performed. The pen tip locus, pen tilt, and pen speed are each processed in time series, that is, normalization (2f) is performed. This normalized data is data unique to the signer and can be referred to as profile data.

  In the registration mode, reference data is generated (3a) and feature data is extracted (3b) from normalized data, that is, profile data. This feature data is information that represents a unique habit of each signer. This feature data is composed of a plurality of authentication factors such as a pen tip movement locus, a pen tilt, and a pen speed. When the handwriting is a person who always holds the pen and the pen tilt is constant, it is desirable to authenticate the signature with an emphasis on the pen tilt. In addition, in the case of a person who moves the pen quickly with the individual's trap, it is desirable to authenticate the signature with an emphasis on the pen speed. In this embodiment, a feature function parameter is set as a parameter for performing such weighting. For example, if the normalized data is written by writing the same signature three times to the signer, three signer-specific profile data can be obtained. This finds the person's trap and generates feature function parameters. The average value of the three profile data is used as reference data. Then, the feature function parameter and the reference data are registered in the database 4.

In the authentication mode, feature extraction (5a) is further performed from profile data which is normalized data. For example, the feature factor extraction unit extracts three factors: pen tip locus, pen tilt, and pen speed. For signers whose pen speed changes each time a signature is made, If you authenticate, the error may increase. In some cases, it is better to extract only data that is the best feature for the authentication mode and perform authentication. Therefore, the profile data having characteristics optimal for authentication is reconstructed (5b), and the reconstructed profile data is compared with reference data (5c). In other words, it can be said that the reconstruction of the profile data is weighted based on the signature of the signer. In the authentication mode, since the signature is usually once, profile data is created from a single signature operation. And the comparison with the reference data in the database 4 is performed, but since the signature is not always the same, when comparing the profile data of one signature with the reference data, even the person himself is not the person himself / herself. May lead to the wrong conclusion. Therefore, an allowable range of difference is set by the feature function parameter. Thereby, highly reliable signature authentication is possible.
In the registration mode, the reference data registration unit 3 and the database 4 are controlled by the handwriting registration application software. In the authentication mode, the data verification unit 5 is controlled by handwriting authentication application software.

  The signature pad of this embodiment can also detect a three-dimensional position. A three-dimensional position detection method will be described later. By detecting the position in three dimensions, the tilt of the pen can also be considered as an authentication factor. For right-handed and left-handed people, the pen tilt is completely opposite, so a signature pad that can detect a three-dimensional position is less likely to make a mistake between right-handed and left-handed people. This is a feature that cannot be achieved by a device that authenticates a signature in two dimensions, and is a great advantage of the signature pad of this embodiment.

FIG. 3 shows a basic configuration example of the optical position detection device 100 that can be used in the signature feature capturing device 1 according to the present embodiment. The optical position detection apparatus 100 in FIG. 3 includes a detection unit 200 and a processing unit 300, and the detection unit 200 includes an irradiation unit EU and a light receiving unit RU.
Note that the signature feature capturing device 1 is not limited to the form realized by using the optical position detection device 100 including the detection unit 200 and the processing unit 300 as described above. The functions of the detection unit 200 and the processing unit 300 may be realized by an information processing device (such as a PC), and the irradiation unit EU and the light receiving unit RU and the information processing device may operate in conjunction with each other.

The detection unit 200 detects information (for example, coordinate information and reflectance information) of the writing tool OB based on the light reception result of the reflected light LR due to the irradiation light LT reflected by the writing tool OB (pen). Specifically, for example, in the detection unit 200, the detection area RDET, which is an area where the writing instrument OB is detected, is a space above the target surface 20 along the XY plane, that is, a space in the Z direction. Then, at least the X coordinate information and the Y coordinate information of the writing instrument OB present in the detection area RDET are detected. A method for detecting coordinate information by the detection unit 200 will be described later.
The detection area RDET is an area (area) where the writing tool OB is detected. Specifically, for example, the light receiving unit RU receives reflected light LR caused by the irradiation light LT being reflected by the writing tool OB. This is the area where the writing instrument OB can be detected. More specifically, it is an area where the light receiving unit RU can receive the reflected light LR and detect the writing instrument OB, and the detection accuracy can be ensured within an acceptable range.

The processing unit 300 performs various processes based on the writing instrument OB detected by the detection unit 200. The function of the processing unit 300 can be realized by a processor such as a CPU, a program executed by the processor, a dedicated IC, or the like.
The irradiation unit EU emits irradiation light LT to the detection area RDET. As will be described later, the irradiation unit EU includes a light source unit composed of a light emitting element such as an LED (light emitting diode), and emits, for example, infrared light (near infrared ray close to the visible light region) when the light source unit emits light. .
The light receiving unit RU receives the reflected light LR generated by the irradiation light LT being reflected by the writing instrument OB. The light receiving unit RU may include a plurality of light receiving units PD. For example, a photodiode or a phototransistor can be used as the light receiving unit PD.

  FIG. 4 shows a specific configuration example of the light receiving unit RU of the present embodiment. In the configuration example of FIG. 4, the light receiving unit RU includes a light receiving unit PD. The light receiving unit PD is provided with a slit or the like (incident light limiting unit) for limiting the angle (incident on the YZ plane) on which incident light is incident, and the reflected light from the writing instrument OB present in the detection area RDET. LR is received. The detection unit 200 detects X coordinate information and Y coordinate information based on the light reception result of the light receiving unit PD. The irradiation unit EU emits irradiation light LT to the detection area RDET. The detection area RDET is an area along the XY plane. In addition, although the structural example of FIG. 4 is comprised with one light receiving unit, it is good also as a structure containing two or more light receiving units.

FIGS. 5A and 5B show a configuration example of the light receiving unit PD having the slit SLT (incident light limiting unit). As shown in FIG. 5A, a slit SLT is provided in front of the light receiving element PHD to limit incident incident light. The slit SLT is provided along the XY plane, and can limit the angle in the Z direction where incident light is incident. That is, the light receiving unit PD can receive incident light incident at a predetermined angle defined by the slit width of the slit SLT.
FIG. 5B is a plan view seen from above of the light receiving unit having the slit SLT. For example, a wiring board PWB is provided in a housing (case) such as aluminum, and the light receiving element PHD is mounted on the wiring board PWB.

  In FIG. 6, the detailed structural example of the irradiation part EU of this embodiment is shown. The irradiation unit EU in the configuration example of FIG. 6 includes light source units LS1 and LS2, a light guide LG, and an irradiation direction setting unit LE. Moreover, the reflective sheet RS is included. The irradiation direction setting unit LE includes the optical sheet PS and the louver film LF. Note that the irradiation unit EU of the present embodiment is not limited to the configuration of FIG. 6, and various components such as omitting some of the components, replacing them with other components, and adding other components. Variations are possible.

  The light source units LS1 and LS2 emit light source light and have light emitting elements such as LEDs (light emitting diodes). The light source units LS1 and LS2 emit, for example, infrared light (near infrared light close to the visible light region). That is, the light source light emitted from the light source units LS1 and LS2 is light in a wavelength band that is generally efficiently reflected by a pen used for a signature, and light in a wavelength band that is not so much included in ambient light as disturbance light. It is desirable that Specifically, infrared light having a wavelength near 850 nm, infrared light near 950 nm, which is light in a wavelength band not so much included in environmental light, and the like.

  The light source unit LS1 is provided on one end side of the light guide LG as indicated by F1 in FIG. The second light source unit LS2 is provided on the other end side of the light guide LG as indicated by F2. Then, the light source unit LS1 emits the light source light to the light incident surface on one end side (F1) of the light guide LG, thereby emitting the irradiation light LT1, and detecting the first irradiation light intensity distribution LID1. Form (set) the area. On the other hand, the light source unit LS2 emits the second light source light LT2 by emitting the second light source light to the light incident surface on the other end side (F2) of the light guide LG, so that the first irradiation light is emitted. A second irradiation light intensity distribution LID2 having an intensity distribution different from that of the intensity distribution LID1 is formed in the detection area. In this way, the irradiation unit EU can emit irradiation light having different intensity distributions according to the position in the detection area RDET.

The light guide LG (light guide member) guides the light source light emitted from the light source units LS1 and LS2. For example, the light guide LG guides the light source light from the light source units LS1 and LS2 along a curved light guide path, and the shape thereof is a curved shape. Specifically, in FIG. 6, the light guide LG has an arc shape. In FIG. 6, the light guide LG has an arc shape with a center angle of 180 degrees, but may have an arc shape with a center angle smaller than 180 degrees. The light guide LG is formed of, for example, a transparent resin member such as acrylic resin or polycarbonate.
At least one of the outer peripheral side and the inner peripheral side of the light guide LG is processed to adjust the light output efficiency of the light source light from the light guide LG. As a processing method, for example, various methods such as a silk printing method for printing reflective dots, a molding method for forming irregularities with a stamper or injection, and a groove processing method can be adopted.

  The irradiation direction setting unit LE realized by the prism sheet PS and the louver film LF is provided on the outer peripheral side of the light guide LG and receives light source light emitted from the outer peripheral side (outer peripheral surface) of the light guide LG. And the irradiation light LT1 and LT2 in which the irradiation direction was set to the direction which goes to the outer peripheral side from the inner peripheral side of the light guide LG of curved shape (arc shape) are radiate | emitted. That is, the direction of the light source light emitted from the outer peripheral side of the light guide LG is set (restricted) to an irradiation direction along, for example, the normal direction (radial direction) of the light guide LG. Thereby, irradiation light LT1 and LT2 come to radiate | emit radially in the direction which goes to the outer peripheral side from the inner peripheral side of the light guide LG.

  Such setting of the irradiation direction of the irradiation light LT1, LT2 is realized by the prism sheet PS, the louver film LF, or the like of the irradiation direction setting unit LE. For example, the prism sheet PS sets the direction of the light source light emitted at a low viewing angle from the outer peripheral side of the light guide LG to the normal direction side so that the peak of the light emission characteristic is in the normal direction. The louver film LF blocks (cuts) light in a direction other than the normal direction (low viewing angle light).

  As described above, according to the irradiation unit EU of the present embodiment, the light source portions LS1 and LS2 are provided at both ends of the light guide LG, and the light source portions LS1 and LS2 are alternately turned on to thereby generate two irradiation light intensity distributions. Can be formed. That is, the irradiation light intensity distribution LID1 in which the intensity on one end side of the light guide LG is increased and the irradiation light intensity distribution LID2 in which the intensity on the other end side of the light guide LG is increased can be alternately formed.

  By forming such irradiation light intensity distributions LID1 and LID2 and receiving the reflected light of the object by the irradiation light of these intensity distributions, the influence of ambient light such as ambient light is minimized. It is possible to detect an object having a high height. That is, it is possible to cancel out the infrared component included in the disturbance light, and it is possible to minimize the adverse effect of the infrared component on the detection of the object.

<Coordinate detection method using optical position detector>
FIGS. 7A and 5B are diagrams for explaining a method of detecting coordinate information by the optical position detection device 100 that can be used in the signature feature capturing device 1 according to the present embodiment.

  E1 in FIG. 7A is a diagram showing the relationship between the irradiation direction angle of the irradiation light LT1 and the intensity of the irradiation light LT1 at that angle in the irradiation light intensity distribution LID1 of FIG. At E1 in FIG. 7A, the intensity is highest when the irradiation direction is the direction DD1 in FIG. 7B (left direction). On the other hand, the intensity is lowest when the direction is DD3 (right direction), and the intensity is intermediate in the direction DD2. Specifically, the intensity of the irradiation light monotonously decreases with respect to the angle change from the direction DD1 to the direction DD3, for example, changes linearly (linearly). In FIG. 7B, the center position of the arc shape of the light guide LG is the arrangement position PE of the irradiation unit EU.

  Further, E2 in FIG. 7A is a diagram showing the relationship between the angle of the irradiation direction of the irradiation light LT2 and the intensity of the irradiation light LT2 at that angle in the irradiation light intensity distribution LID2 of FIG. At E2 in FIG. 7A, the intensity is highest when the irradiation direction is the direction of DD3 in FIG. 7B. On the other hand, the intensity is the lowest in the direction of DD1, and the intermediate intensity in the direction of DD2. Specifically, the intensity of irradiation light monotonously decreases with respect to an angle change from the direction DD3 to the direction DD1, and changes linearly, for example. In FIG. 7A, the relationship between the angle in the irradiation direction and the intensity is linear, but the present embodiment is not limited to this, and may be a hyperbolic relationship, for example.

  Then, as shown in FIG. 7B, it is assumed that the writing instrument OB exists in the direction DDB of the angle φ. Then, when the irradiation light intensity distribution LID1 is formed by the light source unit LS1 emitting light (in the case of E1), as shown in FIG. 7A, the writing instrument OB present in the direction of DDB (angle φ). The intensity at the position is INTa. On the other hand, when the irradiation light intensity distribution LID2 is formed by light emission from the light source unit LS2 (in the case of E2), the intensity at the position of the writing instrument OB existing in the direction of DDB is INTb.

  Therefore, the direction DDB (angle φ) in which the writing instrument OB is located can be specified by obtaining the relationship between the strengths INTa and INTb. For example, if the distance of the writing instrument OB from the position PE of the optical position detection device is obtained by the method shown in FIGS. 8A and 8B described later, writing is performed based on the obtained distance and the direction DDB. The position of the tool OB can be specified. Alternatively, as shown in FIG. 9 to be described later, two irradiation units EU1 and EU2 are provided as the irradiation unit EU, and directions DDB1 (φ1) and DDB2 (φ2) of the writing instrument OB with respect to each irradiation unit of EU1 and EU2 are obtained. For example, the position of the writing instrument OB can be specified by the directions DDB1 and DDB2 and the distance DS between the irradiation units EU1 and EU2.

  In order to obtain such a relationship between the intensity INTa and INTb, in this embodiment, the light receiving unit RU receives the reflected light (first reflected light) of the writing instrument OB when the irradiation light intensity distribution LID1 is formed. . If the detected light reception amount of the reflected light at this time is Ga, this Ga corresponds to the intensity INTa. The light receiving unit RU receives the reflected light (second reflected light) of the writing instrument OB when the irradiation light intensity distribution LID2 is formed. When the detected light reception amount of the reflected light at this time is Gb, this Gb corresponds to the intensity INTb. Therefore, if the relationship between the detected light reception amounts Ga and Gb is obtained, the relationship between the intensity INTa and INTb can be obtained, and the direction DDB in which the writing instrument OB is located can be obtained.

For example, the control amount (for example, current amount), the conversion coefficient, and the emitted light amount of the light source unit LS1 are Ia, k, and Ea, respectively. In addition, the control amount (current amount), the conversion coefficient, and the amount of emitted light of the light source unit LS2 are Ib, k, and Eb, respectively. Then, the following expressions (1) and (2) are established.
Ea = k · Ia (1)
Eb = k · Ib (2)

Further, let fa be the attenuation coefficient of the light source light (first light source light) from the light source unit LS1, and let Ga be the detected received light amount of the reflected light (first reflected light) corresponding to this light source light. Further, the attenuation coefficient of the light source light (second light source light) from the light source unit LS2 is fb, and the detected light reception amount of the reflected light (second reflected light) corresponding to the light source light is Gb. Then, the following expressions (3) and (4) are established.
Ga = fa · Ea = fa · k · Ia (3)
Gb = fb · Eb = fb · k · Ib (4)
Therefore, the ratio of the detected light reception amounts Ga and Gb can be expressed as the following equation (5).
Ga / Gb = (fa / fb). (Ia / Ib) (5)

Here, Ga / Gb can be specified from the light reception result in the light receiving unit RU, and Ia / Ib can be specified from the control amount of the irradiation unit EU. Intensities INTa and INTb and attenuation coefficients fa and fb in FIG. 5A are in a unique relationship. For example, when the attenuation coefficients fa and fb are small values and the attenuation is large, it means that the strengths INTa and INTb are small. On the other hand, when the attenuation coefficients fa and fb are large and the attenuation is small, it means that the strengths INTa and INTb are large. Therefore, the direction, position, etc. of the object can be obtained by obtaining the attenuation factor ratio fa / fb from the above equation (5).
More specifically, one control amount Ia is fixed to Im, and the other control amount Ib is controlled so that the detected light reception amount ratio Ga / Gb becomes 1. For example, the light source units LS1 and LS2 are controlled to turn on alternately in reverse phase, the detected received light amount waveform is analyzed, and the other control is performed so that the detected waveform is not observed (Ga / Gb = 1). The amount Ib is controlled. Then, from the other control amount Ib = Im · (fa / fb) at this time, the ratio fa / fb of the attenuation coefficient is obtained, and the direction, position, etc. of the object are obtained.

Further, as in the following formulas (6) and (7), control may be performed so that Ga / Gb = 1 and the sum of the control amounts Ia and Ib is constant.
Ga / Gb = 1 (6)
Im = Ia + Ib (7)
Substituting the above equations (6) and (7) into the above equation (5), the following equation (8) is established.
Ga / Gb = 1 = (fa / fb) · (Ia / Ib)
= (Fa / fb) · {(Im−Ib) / Ib} (8)
From the above equation (8), Ib is expressed as the following equation (9).
Ib = {fa / (fa + fb)} · Im (9)
Here, if α = fa / (fa + fb), the above equation (9) is expressed as the following equation (10), and the attenuation coefficient ratio fa / fb is expressed by the following equation (11) using α. It is expressed in
Ib = α · Im (10)
fa / fb = α / (1-α) (11)
Therefore, if Ga / Gb = 1 and control is performed so that the sum of Ia and Ib becomes a constant value Im, α is obtained from the current Ib and Im by the above equation (10), and the obtained α is increased. By substituting into Equation (11), the ratio fa / fb of the attenuation coefficient can be obtained. This makes it possible to obtain the direction, position, etc. of the object. Further, by controlling so that Ga / Gb = 1 and the sum of Ia and Ib becomes constant, it becomes possible to cancel the influence of disturbance light and the like, and the detection accuracy can be improved.

Next, an example of a technique for detecting coordinate information of an object using the optical detection system of the present embodiment will be described. FIG. 8A is an example of a signal waveform for light emission control of the light source units LS1 and LS2. The signal SLS1 is a light emission control signal of the light source unit LS1, the signal SLS2 is a light emission control signal of the light source unit LS2, and these signals SLS1 and SLS2 are in reverse phase. The signal SRC is a light reception signal.
For example, the light source unit LS1 is turned on (emits light) when the signal SLS1 is at the H level, and is turned off when the signal SLS1 is at the L level. The light source unit LS2 is turned on (emits light) when the signal SLS2 is at the H level, and is turned off when the signal SLS2 is at the L level. Accordingly, in the first period T1 in FIG. 8A, the light source unit LS1 and the light source unit LS2 are alternately turned on. That is, the light source unit LS2 is turned off during the period when the light source unit LS1 is turned on. Thereby, an irradiation light intensity distribution LID1 as shown in FIG. 6 is formed. On the other hand, the light source unit LS1 is turned off during the period when the light source unit LS2 is turned on. Thereby, an irradiation light intensity distribution LID2 as shown in FIG. 6 is formed.

  As described above, the detection unit 200 performs control of alternately emitting (lighting) the light source unit LS1 and the light source unit LS2 in the first period T1. And in this 1st period T1, the direction where the target object located seen from the optical position detection apparatus (irradiation part) is detected. Specifically, for example, in the first period T1, light emission control is performed such that Ga / Gb = 1 and the sum of the control amounts Ia and Ib is constant as in the above-described formulas (6) and (7). Do. Then, as shown in FIG. 7B, the direction DDB in which the writing instrument OB is located is obtained. For example, the ratio fa / fb of the attenuation coefficient is obtained from the above equations (10) and (11), and the direction DDB in which the writing instrument OB is located is obtained by the method described in FIGS. 7 (A) and 7 (B).

In the second period T2 following the first period T1, the distance to the writing instrument OB (the distance in the direction along the direction DDB) is detected based on the light reception result of the light receiving unit RU. Then, the position of the object is detected based on the detected distance and the direction DDB of the writing instrument OB. That is, in FIG. 7B, the X and Y coordinate positions of the writing tool OB can be specified by obtaining the distance from the arrangement position PE of the optical position detection device to the writing tool OB and the direction DDB in which the writing tool OB is located. . In this manner, the position of the writing instrument OB can be specified by obtaining the distance from the time difference between the lighting timing of the light source and the light receiving timing and combining this with the angle result.
Specifically, in FIG. 8A, the time Δt from the light emission timing of the light source units LS1 and LS2 by the light emission control signals SLS1 and SLS2 to the timing at which the light reception signal SRC becomes active (the timing at which the reflected light is received). To detect. That is, the time Δt from when the light from the light source units LS1 and LS2 is reflected by the writing instrument OB and received by the light receiving unit RU is detected. By detecting this time Δt, since the speed of light is known, the distance to the writing instrument OB can be detected. That is, the shift width (time) of the arrival time of light is measured, and the distance is obtained from the speed of light.

In addition, since the speed of light is quite high, there is also a problem that it is difficult to detect the time Δt by obtaining a simple difference using only an electric signal. In order to solve such a problem, it is desirable to modulate the light emission control signal as shown in FIG. Here, FIG. 8B is a schematic signal waveform example schematically representing light intensity (current amount) by the amplitude of the control signals SLS1 and SLS2.
Specifically, in FIG. 8B, the distance is detected by, for example, a known continuous wave modulation TOF (Time Of Flight) method. In this continuous wave modulation TOF method, continuous light that is intensity-modulated with a continuous wave having a constant period is used. Then, while irradiating the intensity-modulated light and receiving the reflected light a plurality of times at time intervals shorter than the modulation period, the waveform of the reflected light is demodulated and the phase difference between the irradiated light and the reflected light is obtained. Thus, the distance is detected. In FIG. 8B, the intensity of only the light corresponding to one of the control signals SLS1 and SLS2 may be modulated. Further, instead of the clock waveform as shown in FIG. 8B, a waveform modulated by a continuous triangular wave or Sin wave may be used. Further, the distance may be detected by a pulse modulation TOF method using pulsed light as continuously modulated light. Details of the distance detection method are disclosed in, for example, Japanese Patent Application Laid-Open No. 2009-8537.

  In FIG. 9, the modification of the irradiation part EU of this embodiment is shown. In FIG. 9, first and second irradiation units EU1 and EU2 are provided as the irradiation unit EU. These first and second irradiation units EU1, EU2 are arranged apart by a given distance DS in the direction along the surface of the detection area RDET of the writing instrument OB. That is, they are arranged apart by a distance DS along the X-axis direction in FIG.

The first irradiation unit EU1 emits first irradiation light having different intensities according to the irradiation direction radially. The second irradiation unit EU2 emits second irradiation light having different intensities according to the irradiation direction radially. The light receiving unit RU writes the first reflected light from the first irradiation light from the first irradiation unit EU1 reflected by the writing tool OB and the second irradiation light from the second irradiation unit EU2. Second reflected light is received by being reflected by the tool OB. Then, the detection unit 200 detects the position POB of the writing instrument OB based on the light reception result at the light receiving unit RU.
Specifically, the detection unit 200 detects the direction of the writing instrument OB relative to the first irradiation unit EU1 as the first direction DDB1 (angle φ1) based on the light reception result of the first reflected light. Further, based on the reception result of the second reflected light, the direction of the writing instrument OB relative to the second irradiation unit EU2 is detected as the second direction DDB2 (angle φ2). Then, based on the detected first direction DDB1 (φ1) and second direction DDB2 (φ2), and the distance DS between the first and second irradiation units EU1, EU2, the position POB of the writing instrument OB. Ask for.

  According to the modification of FIG. 9, the position POB of the writing tool OB can be detected without obtaining the distance between the optical position detection device and the writing tool OB as shown in FIGS. 8A and 8B. It becomes like this.

<Acquisition of position information in three dimensions of signature feature capture device>
Next, a method for acquiring the three-dimensional position information of the signature feature capturing apparatus 1 will be described.
FIG. 10 shows a configuration example of the light receiving unit RU of the present embodiment. In this configuration example, the light receiving unit RU includes three light receiving units PD1 to PD3 (a plurality of light receiving units in a broad sense), and the light receiving units PD1 to PD3 are arranged along a direction intersecting the target surface 20. Specifically, the three light receiving units PD <b> 1 to PD <b> 3 are arranged at positions having different heights (distances from the target surface 20) in the direction intersecting the target surface 20. Alternatively, when the target surface is a surface along the XY plane, the height in the direction intersecting the target surface is different and the X-axis positions are different.

  The light receiving units PD <b> 1 to PD <b> 3 have an incident light limiting unit that controls incident light in a direction intersecting the target surface 20. Specifically, each of the light receiving units PD1 to PD3 includes a slit or the like for limiting an incident angle (for example, an angle in the Z direction) of incident light, and is reflected from the writing instrument OB present in each of the detection areas RDET1 to RDET3. The light LR is received. For example, the light receiving unit PD1 receives the reflected light LR from the writing instrument OB present in the detection area RDET1, but does not receive the reflected light LR from the writing instrument OB present in the other detection areas RDET2 and RDET3. The irradiation unit EU emits irradiation light LT to the three detection areas RDET1 to RDET3. Each of the detection areas RDET1 to RDET3 is an area set in multiple layers with respect to the target surface along the XY plane.

  With such a configuration, it is possible to detect where the writing tool OB is located in which detection area of the three detection areas RDET1 to RDET3. That is, position detection information (data) related to the Z coordinate of the writing instrument OB can be detected. Thereby, when the writing instrument OB has a longitudinal shape, the inclination angle of the writing instrument OB (the angle between the vertical line of the target surface 20 and the longitudinal direction of the writing instrument OB) can be detected. This makes it possible to detect in real time the angle at which the signer holds the pen.

  As described above, in the signature pad of the present invention, it has been described that three-dimensional position information can be acquired by providing a plurality of light receiving units. By acquiring the three-dimensional position information, the tilt of the pen is also considered as an authentication factor. Right-handed and left-handed people have a completely opposite pen tilt, so using this technique reduces the chances of mistakes between right-handed and left-handed people.

  However, it is not always necessary for the signature pad of the present invention to acquire position information in three dimensions. Even if the pen inclination is not used as an authentication factor, if the necessary authentication accuracy is obtained by the two-dimensional movement of the pen tip moving on the target surface 20, as shown in FIG. It is only necessary to provide a unit.

<Data acquisition method with signature feature capture device>
Next, a data acquisition method in the signature feature capturing apparatus 1 will be described.
First, it is necessary to perform calibration for setting a reference position for obtaining the position of the writing instrument OB. Here, as a specific example, a position when the writing instrument OB is completely brought into contact with the target surface 20 is set as a reference position.
Specifically, the tip of the writing instrument OB is arranged at a position where the signature of the target surface 20 is started, and reflectance information is acquired as calibration information based on the amount of light received by the light receiving unit at that time. Using this acquisition result as a reference, by moving the writing tool OB, the light receiving result received by the light receiving unit changes, and in which direction on the XY plane the writing tool OB has moved is calculated, and the X coordinate Information and Y coordinate information are acquired. The method for acquiring the coordinate information is as described above in the description of the optical position detection device.

  In addition, there is a possibility that a factor such as a change in irradiation light intensity may occur during the period from the calibration to the actual detection process. In that case, reflectance information at a certain time T1 and another time T2 may be detected, respectively, and the difference between the reflectance information at T1 and the reflectance information at T2 may be obtained. In this case, since it is not a comparison with the reference position, the absolute position of the writing instrument cannot be obtained, but the movement amount between T1 and T2 (for example, the movement amount in the longitudinal direction or the rotation in the rotation direction). Amount). At this time, if the interval between T1 and T2 is set to a sufficiently short interval, it is possible to suppress the influence of a change in the irradiation light intensity or the like.

<Example of signature pad configuration>
Next, a specific configuration example of the signature pad will be described. FIG. 11 is an overview of the signature pad SP of the present embodiment. As an overview, an optical position detection device 100 and a clip portion 8 are provided on a flat plate portion 7. The optical position detection apparatus 100 is provided with first and second irradiation units EU1 and EU2 with the light receiving unit RU interposed therebetween. The detailed configuration of EU1 and EU2 is as shown in FIG.

  In the plane of the flat plate part 7, the area where the irradiation light from the first and second irradiation units EU1, EU2 reaches becomes the target surface 20 for detecting the position of the writing instrument OB. The clip portion 8 receives an urging force by an elastic member such as a torsion coil spring and can sandwich the sheet 9 between the flat plate portions 7. The signature pad assumes that the signer signs the range of the target surface 20 of the paper 9.

  FIG. 12 is a diagram for explaining the start of detection by providing a detection area. A space of about 10 mm above the target surface 20 is set as the detection area RDET. When the writing instrument OB enters the detection area RDET, the optical position detection device 100 detects a change in reflected light, and can detect that a pen has entered the signature range of the paper 9. At this timing, the signature feature of the signer is started to be captured. This is called a profile data capturing start process, and is automatically performed by the signature feature capturing apparatus 1 inside the signature pad SP.

  When the signer finishes writing the signature and removes the pen from the detection area RDET, it is determined that the signature operation is completed, and the reflected light data acquisition ends. This is called profile data capturing end process, and is automatically performed by the signature feature capturing apparatus 1 in the signature pad SP.

  Since the profile data reading start process and profile data reading end process are automatically performed, the signature feature capturing apparatus 1 can perform processing in the shortest necessary time, and the position of the writing instrument OB can be detected. The burden on the CPU (central processing unit) that performs various processes (calculations) of business information is minimized. Further, following the profile data reading completion step, the process of authentication factor extraction and authentication factor generation is entered. This is performed by the authentication factor extraction unit 2 shown in FIG. Thereafter, the process of authenticating the authenticity of the signer by comparison with the database 4 is as described above.

<Details of signature authentication method>
The signature authentication is performed based on various authentication factors, and details thereof will be described. As described above, since the signature feature capturing device 1 detects the movement of the writing instrument OB, the authentication factor is extracted based on the pen position information, and unique profile data for each signer is generated. . FIG. 13 shows an example of data in which authentication factors that are the basis of this profile data are arranged in time series. For example, it is assumed that “John Smith” is signed.

  Here, the pen tip position detection information PEN is a signal waveform in which the light receiving unit RU of the signature feature capturing apparatus 1 displays the received light intensity detected at the time of signing by the signer in time series. By calculating the detection of the X-coordinate and Y-coordinate described above for this signal waveform, it is possible to calculate the change in the position of the tip of the writing instrument OB that is the pen tip, and as a result, a part of the signal waveform It can be determined that “John” is written and “b” part of the signal waveform is written “Smith”.

  The pen tilt information TIL is a signal waveform indicating a change in tilt of the writing instrument OB (pen) calculated by the signature feature capturing device 1 in time series. This signal level has an almost constant value during the signing operation, and it can be seen that this signer has a tendency to sign with the pen tilt always kept constant. The pen speed information VEL indicates a value obtained by dividing the movement amount of the writing tool OB (pen) calculated by the signature feature capturing apparatus 1 by a unit time, that is, a change in the pen speed. The level of the signal is lower in the part b than in the part a. This shows that this signer is more likely to write pen speeds more slowly when writing the last name "Smith" than when writing the first name "John".

  In authenticating the signature, profile data is created from the authentication factor shown in FIG. The profile data is compared with the reference data. First, a handwriting image (for example, bitmap data) is generated from the pen tip position detection information PEN. Then, the handwriting image similarity is compared and compared with the handwriting image of the reference data. For comparison of the image data, handwriting authentication software or the like may be prepared.

  In the present embodiment, since the signature feature capturing device 1 can detect the movement of the object on the object surface 20, it is possible to create bit mat data of the handwriting. In the above-described example, the writing tool OB (pen) A method has been described in which the position of the tip of the handwriting is detected, converted into a handwritten image, and true / false determination is performed from the shape of the handwritten image.

  However, it is not always necessary to create a handwriting image. When only the signature authentication is performed, it is also possible to compare the reflected light signal waveform itself without calculating the X coordinate and the Y coordinate which are the positions of the writing instrument OB (pen). That is, at the time of registration of the reference data, the signal waveform of the reflected light itself is registered as reference data, and at the time of authentication, the signal waveform when the signer performs a signature operation is used as profile data, and the profile data is compared with the reference data. . This is because the signature feature capturing apparatus 1 used in the present embodiment uses a very characteristic light emission method, so that the signal waveform of the intensity level of the light reflected from the writing light OB (pen) is This can be realized because it has a unique pattern such as a voiceprint and can be directly used as profile data.

1 signature feature capturing device, 2 authentication factor extraction unit, 3 reference data registration unit,
4 database, 5 authentication section,
20 target surface, 100 optical position detection device, 200 detection unit, 210 detection unit,
300 processing unit, EU irradiation unit, LE irradiation direction setting unit, LF louver film,
LG light guide, OB object, PD light receiving unit,
PD1 first light receiving unit, PD2 second light receiving unit,
PD3 Third light receiving unit, PHD light receiving element, PS prism sheet,
PS optical sheet, PWB wiring board, RE1 first reflection part, RE2 second reflection part,
RS reflection sheet, RU light receiving part, SLT slit,
SP signature pad,
PEN Position detection information.

Claims (4)

A flat plate portion having a plane portion;
An irradiation unit that emits irradiation light; and
A light receiving unit for receiving reflected light by the irradiation light being reflected by an object;
Based on the light reception result of the light receiving unit, a detection unit for detecting information for detecting the position of the object;
A profile data recording unit that arranges the position detection information in time series and records it as profile data;
A database for storing reference data in which specific information is arranged in time series;
A data collation unit for collating the profile data with the reference data;
Signature pad, characterized by having When the detection unit detects that the object has entered a predetermined space in contact with the planar portion, a profile data acquisition start process for starting recording of the position detection information;
When the detection unit detects that the object has left the predetermined space, and includes a profile data capturing end step for ending the information recording for position detection.
2. The signature pad according to claim 1, wherein the profile data is collated with the reference data in the data collating unit following the profile data capturing end process.   The signature pad according to claim 1, wherein the irradiation light is an infrared ray.   The signature pad according to any one of claims 1 to 3, further comprising a clip portion that sandwiches a sheet-like medium in a part of the flat plate portion.

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