JP2006185299A - Iris identification device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce influence of a peripheral portion of an iris by a simple configuration to improve iris identification accuracy, in an iris information sensor disposed with pixels in a polar-coordinate state. <P>SOLUTION: This iris identification device has: a polar-coordinate sensor part 10a forming an image of image light from an iris area of an eye on a photoelectric conversion pixel group 31 arranged in the polar-coordinate state, and sequentially operating each photoelectric conversion pixel to read an iris image signal; characteristic extraction code generation parts 15, 16, 17 generating an iris characteristic extraction code on the basis of the read iris image signal; and comparison parts 44, 45, 46, 47 comparing the iris characteristic extraction code generated by the characteristic extraction code generation part and the preregistered iris characteristic extraction code to generate a comparison evaluation value, wherein the comparison evaluation value is generated by a comparison evaluation function having larger weight as it goes to an inner circumferential part of the polar-coordinate sensor part 10a. The comparison evaluation value is compared to a predetermined reference value to perform iris identification. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an iris identification device, and more particularly, in an area sensor in which pixels are arranged in a polar coordinate form, that is, a polar coordinate sensor, it is possible to accurately detect necessary iris information by reducing the influence of the peripheral portion of the iris and having a simple configuration. The present invention relates to a technique for improving iris identification accuracy.

  The applicant of the present application previously proposed to use a polar coordinate sensor in which photoelectric conversion pixels are arranged in polar coordinates for use in an iris information acquisition device and an iris identification device for performing personal identification using the iris pattern of the eye. (JP 2000-36036 A).

  The polar coordinate sensor includes an imaging sensor including photoelectric conversion pixel groups arranged in a polar coordinate pattern, and an error direction between a center of an iris image formed on the imaging sensor and a polar coordinate pole of the imaging sensor. The center position error detecting means for obtaining the size is integrated and formed on one substrate.

  In such an iris information sensor, the iris pattern characteristic extraction specific to the iris of each individual's eye is performed to obtain an iris code. This iris code can be personally authenticated by comparing with an iris code registered in advance.

  In order to perform feature extraction based on the iris pattern of the eye, for example, the imaging signal of the polar coordinate sensor, that is, the pixel output signal is input to the bandpass filter, and the change point of the pixel output signal by the bandpass filter, that is, θ of the iris pattern Extract changes in direction. Then, the extracted signal is compared with a predetermined threshold value to generate an iris code. Alternatively, the feature extraction of the iris pattern may include, for example, a configuration including a band pass filter and a comparator by obtaining an average value of outputs of consecutive N pixels and comparing the average value with the output of the target pixel. Equivalent functions can be achieved and this method can be referred to as a moving average comparison method.

  An iris code conventionally used for personal authentication using an iris pattern is an image of 1024 points from a band obtained by dividing an iris image into, for example, eight analysis bands in the radial direction, and cutting and synthesizing them in the circumferential direction. Retrieve the data. Then, 2-bit data is assigned to each point according to the phase of the pattern (iris pattern) at each point. Therefore, a total of 2048 bits of data is extracted as feature extraction data, that is, as an iris code.

  In the case of personal authentication, an evaluation function that performs an exclusive OR operation for each bit and integrates the iris code obtained from the captured image of the iris and the previously registered iris code, that is, a Hamming distance function, Was used. A value calculated by this evaluation function is used as an evaluation value, and when the evaluation value is smaller than a predetermined value, it is determined that they are the same person. Since the exclusive OR adds up the inconsistent portions, the smaller the value of the obtained evaluation function, the higher the similarity.

  In this case, in the integration of the mismatched portions of the respective bits of the iris code, no weighting is performed on the respective bits, and all the bits are equal with weight = 1.

  However, the outer peripheral portion of the iris is often hidden by eyelashes or eyelashes, and the peripheral portion is affected by the influence, thereby degrading the image quality. Also, depending on the lighting method, the illumination light may be reflected in the iris portion.

Therefore, in order to remove the non-comparable portion of the outer periphery of these irises from the comparison object, mask bits having the same number of bits are used in addition to the 256 bytes (2048 bits) obtained as a conventional iris code. This was dealt with by adding a 512-byte iris code. In other words, by setting the mask bit of the part not to be compared, the part is not compared.
JP 2000-36036 A

  However, in such a conventional technique, the number of bits of the iris code is increased by adding a mask bit, the search speed is reduced, and an extremely high-speed processing device is used when performing personal authentication in real time. There is a disadvantage that the cost of the apparatus increases.

  Also, since mask bits are added in addition to the original iris code, it is necessary to create the mask bits in consideration of the surrounding conditions of the iris, for example, the situation of eyelids and eyelashes, and it takes time to create and set the mask bits. There was also an inconvenience.

  Therefore, in view of the problems in the above-described conventional example, the object of the present invention is to create a concept in which a value indicating a comparison result of each point of the polar coordinate sensor unit is given a greater weight as the points on the inner peripheral portion of the polar sensor unit and integrated. Therefore, the iris recognition rate is improved by reducing the influence of wrinkles and eyelashes on the outer periphery of the iris.

  Another object of the present invention is to remove the adverse effects caused by wrinkles and eyelashes on the outer periphery of the iris without adding a mask bit to the original iris code, so that high-precision identification can be performed at high speed. Is to make it.

  Still another object of the present invention is to enable high-speed and high-precision identification without adding mask bits to the original iris code, and to realize real-time authentication with a simple device configuration and an iris code with a small number of bits. Is to ensure that this is done accurately.

  Still another object of the present invention is to eliminate the trouble of creating a mask bit and adding it to the original iris code, simplifying the device configuration of the iris discriminating apparatus, and improving operability.

  According to one aspect of the present invention, a photoelectric conversion pixel group arranged in a polar coordinate form is provided, and image light from an iris region of an eye is converted to a center of an iris image formed on the pixel group and a polar coordinate pole. Is formed on the photoelectric conversion pixel group so as to coincide with each other, a polar sensor unit that sequentially scans each photoelectric conversion pixel of the photoelectric conversion pixel group to read out the iris image signal, and an iris based on the read out iris image signal A feature extraction code generation unit that generates a feature extraction code, and a comparison unit that generates a comparative evaluation value by comparing the iris feature extraction code generated by the feature extraction code generation unit with a previously registered iris feature extraction code The comparison evaluation value includes a comparison unit that generates a comparison evaluation function having a greater weight toward the inner periphery of the polar sensor unit, and the comparison evaluation value is predicted. Compared with the reference value determined iris identification apparatus and performs iris identification is provided.

  In this case, an exclusive OR operation is performed for each pixel on the iris feature extraction code generated by the feature extraction code generation unit and the iris feature extraction code registered in advance, and the mismatched portion is set to the radial position of each pixel. It is advantageous to generate the comparative evaluation value by weighting and integrating accordingly.

  In addition, the photoelectric conversion pixel group of the polar coordinate sensor unit can be divided into a plurality of concentric analysis bands and have the same number of pixels in the circumferential direction.

  In this case, among the pixel groups arranged along each radial direction, the pixel arranged on the inner peripheral side is the most significant bit side and the pixel arranged on the outer peripheral side is the lowest Each feature extraction data from the pixel group arranged along each radial direction is generated so that each pixel arranged along each radial direction has a weight corresponding to each bit of the binary number so as to be on the bit side The iris identification can be performed by comparing the size of the iris feature extraction code registered in advance with the corresponding feature extraction data.

  Also, in this case, it is advantageous to perform iris identification using only some bits from the most significant bit side in the iris feature extraction data from the pixel groups arranged along the radial directions.

  Further, the iris image signal is read out from the pixel at a predetermined reading start position in the circumferential direction of the polar sensor along the innermost analysis band, and then the analysis band outside the analysis band is read. It is also possible to read out for one round from the reading start position along the line, and then sequentially read out to the outer circumferential side.

  In this case, after reading out the iris image signal for all the pixels from the predetermined readout start position, the readout start position is sequentially shifted in the circumferential direction and readout is performed, and the iris feature extraction generated from the readout image signal is performed. It is advantageous to perform iris identification using an iris feature extraction code generated from an image signal read from a read start position that best matches a previously registered iris feature extraction code.

  Further, in the process of sequentially reading from the predetermined reading start position and performing the reading, once a comparative evaluation value that can be determined to be the same person is obtained, subsequent reading and comparison may be omitted. it can.

  Further, a plurality of iris feature extraction codes generated from iris image signals read in parallel with each of a predetermined number of a plurality of pixels continuous in the circumferential direction as a readout start position are respectively compared with previously registered iris feature extraction codes. It is convenient to perform the iris identification using a comparative evaluation value that best matches among the comparative evaluation values obtained by these comparison and integration circuits.

  According to the present invention, since the weight of the outer peripheral portion of the iris is reduced and the weight of the inner peripheral portion is increased, the influence of wrinkles and eyelashes can be minimized, and the iris identification rate can be improved with a simple device configuration. it can. Further, it is not necessary to add a mask bit, or a configuration in which a mask bit is added to only a part of the area can be adopted, and the number of bits of the iris code can be greatly reduced. For this reason, the size of the iris code can be reduced, and the identification operation can be performed at a high speed.

  In addition, in order to exclude a portion that should not be compared from the comparison target in the iris region, it is not necessary to create a mask bit for a portion that is not the comparison target and combine it with the original iris code. For this reason, it is possible to greatly simplify the manufacturing, setting, and adjustment procedures of the iris identification device. Further, the apparatus configuration can be simplified, and the productivity of the iris identification apparatus as a whole can be improved and the apparatus cost can be reduced.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an example of the configuration of an iris information acquisition device used in an iris identification device according to an embodiment of the present invention. In the figure, the iris information acquisition apparatus includes two wide-angle cameras 1a and 1b and a zoom camera 7. The wide-angle cameras 1a and 1b pick up images of the eyes of the person to be recognized by the CCDs 2a and 2b, and send image signals obtained by reducing noise of the picked-up signals to the iris acquisition controller 6 by the CDS circuits 3a and 3b. To do. The wide-angle cameras 1a and 1b control the CCD drivers 5a and 5b that drive and control the CCDs 2a and 2b based on the synchronization control signals generated by the control units 4a and 4b, and the processing operations of the CDS circuits 3a and 3b. Is controlling.

  The apparatus of FIG. 1 also includes an iris acquisition controller 6. The iris acquisition controller 6 specifies the three-dimensional position of the eye of the person to be recognized based on the image signals input from the wide-angle cameras 1a and 1b, and sends a signal or data indicating the specified result to the zoom camera 7. Output.

  Based on this three-dimensional position, the zoom camera 7 drives and controls the steering motor 7b to move the mirror 8c so that the imaging direction of the zoom camera 7 is directed toward the human eye. The zoom camera 7 controls the zoom / focus motor 7a that drives the zoom lens optical system 8 to focus on the three-dimensional position of the human eye, and the iris image to be imaged is captured by the iris information sensor 10. Control is performed to adjust the zoom amount so as to match the region. The iris acquisition unit 9 in the zoom camera 7 sends the position error and focus error information between the iris image captured by the sensor 10 and the sensor to the iris acquisition controller 6.

  The iris acquisition controller 6 servo-controls each part of the camera system described above until information on the iris part is obtained. When the information of the iris part is obtained, this information, that is, the iris code, is collated with a built-in or pre-registered iris code held by a host computer (not shown) or is collated with the host computer. The host computer may control each part of the camera system, or the sensor part itself may control by each error signal of the iris acquisition part 9.

  Note that the configuration of FIG. 1 includes a zoom lens optical system 8 that adjusts the size of the captured image so that the iris image to be captured matches the imaging region of the sensor 10. However, it is obvious that the present invention does not use such a zoom lens optical system 8 and may use, for example, a single focus lens. For example, in a configuration in which a peephole is provided at a predetermined position on the front surface of the camera and the identification target person is instructed to view the lens portion of the camera from this peephole, a so-called peeping method, the distance between the camera and the eyes Can be set to a predetermined value. Therefore, in such a case, the iris image to be imaged can be made substantially coincident with the imaging area of the sensor 10 without using a zoom lens. In this case, the position of the eyes with respect to the camera is also regulated to a predetermined positional relationship, so that a configuration in which the wide-angle cameras 1a and 1b in FIG. 1 are not used is possible.

  In the configuration of FIG. 1, the mirror 8c is moved so that the imaging direction of the zoom camera 7 is directed toward the eyes. However, in the present invention, instead of the mirror, the eye can be aligned by shifting a VAP (variable vertical prism), an imaging lens or a part thereof in a direction perpendicular to the optical axis.

  In the above configuration, the iris information received by the iris acquisition controller 6 from the iris acquisition unit is an iris code binarized by the iris acquisition unit 9. The detailed configuration of the iris acquisition unit 9 will be described with reference to FIG.

  FIG. 2 shows a schematic configuration of the iris acquisition unit 9 in the iris information acquisition apparatus shown in FIG. The iris acquisition unit 9 shown in the figure includes an iris information sensor 10 including a polar coordinate sensor unit 10a including a plurality of photoelectric conversion pixels arranged in a polar coordinate shape. Each photoelectric conversion pixel of the polar coordinate sensor unit 10a may be constituted by a photodiode, a CCD image pickup element, or a MOS type image pickup element or other photoelectric conversion elements. Further, a position detection unit 10c for detecting a position error between the center of the iris image and the polar coordinate pole of the polar coordinate sensor unit is disposed in the central area 10b of the polar coordinate sensor unit 10a. The position error detection unit 10c can be constituted by, for example, a photodiode divided into four with the polar coordinate pole as the center.

  The apparatus of FIG. 2 also has an LED (light emitting diode) 13 for illumination that is provided on the optical axis of the sensor 10 and illuminates the human eye with visible light. It is advantageous that the light emitting surface of the LED 13 is optically shifted from the light receiving surface of the sensor 10 so that the LED 13 can accurately illuminate human eyes. As the illumination means, in addition to the LED 13, an EL (electroluminescence) element and other arbitrary ones can be used.

  The apparatus of FIG. 2 further includes an iris inner diameter detection circuit 11. The iris inner diameter detection circuit 11 detects the boundary between the pupil and the iris in the radial direction in the captured iris image by level change, that is, performs edge detection, and obtains the inner diameter of the iris image from the result. In this case, although not illustrated in FIG. 2, for example, eight analysis bands (ring bands) for imaging an iris image of the polar coordinate sensor unit 10 a are formed on the inner and outer peripheral portions of the effective pixel portion. Each edge detection pixel is arranged in a ring shape. The iris inner diameter detection circuit 11 detects the boundary between the pupil and the iris by changing the level of the detection signal between the edge detection pixel at the inner periphery and the pixel arranged outside the pixel. Specifically, for example, the level change of the detection signal can be obtained by a difference in values obtained by averaging each pixel output for one round.

  The apparatus of FIG. 2 further includes an iris outer diameter detection circuit 12, and the iris outer diameter detection circuit 12 similarly detects the outer periphery of the iris in the picked-up iris image by level change, that is, performs edge detection. Find the outer diameter. That is, similarly to the iris inner diameter detection circuit, the iris outer diameter detection circuit 12 outputs a detection signal between the pixel for edge detection on the outer peripheral portion of the polar coordinate sensor unit 10a and a pixel arranged inside the pixel. Edge detection can be performed by changing the level.

  The iris outer diameter detection circuit 12 outputs a zoom error signal to the iris acquisition controller 6. The iris inner diameter detection circuit 11 detects the inner diameter of the iris as described above, but generates a deviation between the detected inner diameter and the inner peripheral edge of the sensor 10, that is, a pupil diameter error signal, and sends it to the iris acquisition controller 6. To do.

  The iris acquisition controller 6 controls the brightness of the LED 13 so that this pupil diameter error signal disappears. That is, when the pupil diameter is larger than the inner peripheral edge of the polar coordinate sensor unit 10a, the brightness of the LED 13 is increased, and when the pupil diameter is smaller than the inner peripheral edge of the polar coordinate sensor unit 10a, the brightness of the LED 13 is decreased. Do. Specifically, for example, a servo operation is performed to control the brightness of the LED 13 so that the difference between the output of the edge detection pixel on the inner peripheral side and the output of the effective pixel outside the pixel is maximized.

  As a result, the pupil diameter always matches the inner periphery of the polar sensor unit 10a, and the outer periphery of the polar sensor unit 10a matches the outer diameter of the iris by a steering error signal, a zoom error signal, etc. The iris part is always imaged in accordance with the pixel arrangement pattern on the polar coordinate sensor part 10a.

  Therefore, the radial width of each pixel in the polar coordinate sensor unit 10a may be divided into a necessary resolution, for example, eight equal parts, and the iris code is directly used by using the imaging signal from the sensor 10 having such a polar coordinate sensor unit 10a. Can be generated.

  The imaging signal from the sensor 10 is sent to the high pass filter 14. The high-pass filter 14 extracts the high-frequency component level of the imaging signal and outputs it as a focus control signal. The steering error signal, zoom error signal, and focus control signal as described above are sent to the iris acquisition controller 6 described above. As described above, the iris acquisition controller 6 controls the steering motor 7b and the zoom / focus motor 7a in the zoom camera so that the iris to be imaged coincides with the center of the polar coordinate sensor unit 10a, and the outer diameter of the iris is set to polar coordinates. It is made to correspond to the outer periphery of the sensor part 10a, and a focusing process is performed.

  The timing generator 18 drives the driver 19 of the sensor 10 to perform scanning for outputting a pixel signal in the θ direction (rotation direction) for each analysis band. When the fine adjustment by the feedback process is performed and proper imaging is possible, the read output signal from each pixel is output to the weighted moving average circuit 15 via the read potential holding unit as will be described in detail later. Sent to. The weighted moving average circuit 15 extracts a change point of the transmitted pixel output signal, that is, a change in the θ direction of the iris pattern. Further, the binarization circuit 16 generates an iris code obtained by performing binarization processing on the extracted signal by an inherent comparator. The iris code is sent to the iris acquisition controller 6 via the latch circuit 17. As described above, the iris acquisition controller 6 compares the iris code of each analysis band with the iris code registered in advance in the host computer, and performs personal authentication. Note that the iris code is preferably encrypted or encoded for security and transmitted between the circuit devices.

  According to the above-described method, it is not necessary to use the sensor 10 having a large number of pixels in the radial direction to divide into each analysis band, and the center of the iris is determined, so that the iris image is registered in advance. By doing so, the authentication process can be performed by very simple pattern matching. That is, since the inner diameter and outer diameter of the iris are known, pattern matching can be performed only by rotating at the center of the iris, and the comparison speed can be significantly improved.

  FIG. 3 is an explanatory diagram illustrating an example of the polar coordinate sensor unit 10a of the iris sensor used in the iris identification device according to the embodiment of the present invention, and pixel weighting.

  In FIG. 3, the polar coordinate sensor unit 10a arranges the pixels 31 in the radial direction around the pole o of polar coordinates, for example, along eight analysis bands. Further, the number of pixels in the circumferential direction in each analysis band is equal, and is set to 256, for example. In the central area in the vicinity of the polar coordinate pole o, the aforementioned position error detection unit 10c for detecting a positional error between the center of the iris image and the polar coordinate pole o of the polar coordinate sensor unit 10a is arranged. The position error detection unit 10c in FIG. 3 is different from the one shown in FIG. 2, but is composed of photodiodes divided into four with the pole o of polar coordinates as the center.

  In the present invention, when the iris code generated from the iris image information read by the polar coordinate sensor unit 10a is compared with an iris code registered in advance, the inner peripheral part rich in iris feature information is more weighted. Use an evaluation function.

  For example, as shown in (1) of FIG. 3, the polar coordinate sensor unit 10a compares the evaluation functions with the innermost circumference weight = 4, the following = 4, = 3,. . Alternatively, as shown in (2) of FIG. 3, the innermost circumference weight = 8, the following = 7, = 6,..., And the outermost circumference weight = 1. Alternatively, as shown in (3) of FIG. 3, the innermost circumference weight = 8, the following = 4, = 2,..., The outermost circumference weight = 1, or as shown in (4) of FIG. The innermost weight = 128, the following = 64, = 32,..., And the outermost weight = 1.

  That is, for example, an exclusive OR operation is performed on the data of each pixel and pre-registered data, and the value obtained by the exclusive OR operation, that is, “1” or “0” is set to the radius as described above. Multiply the direction by the weight value that is greater in the inner circumference, and add up.

  By using such an integrated value as a comparative evaluation value and comparing it with a predetermined reference value, it is possible to identify the iris, but by using a comparative evaluation function having a weight on the inner peripheral portion, The weight becomes smaller. Therefore, the influence on the evaluation value of wrinkles and eyelashes that appear only on the outer peripheral portion can be considerably reduced. Therefore, it is possible to perform iris identification by comparing the entire data read by the polar sensor unit without removing the wrinkles and the like using a mask bit.

  Also, for example, as shown in (4) of FIG. 3, a feature extraction code is created so that the inner periphery is on the MSB side and the outer periphery is on the LSB side, and the weighting method is devised. By weighting the power, iris identification can be performed by simply comparing the feature extraction code with previously registered code data. That is, it is determined that the similarity is higher as the result of integrating the difference value obtained by the size comparison at each feature point in the circumferential direction by the number of feature points (that is, by the number of pixels) in the circumferential direction is smaller. Can do. Therefore, it is possible to perform personal authentication depending on whether or not the integrated result is equal to or less than a predetermined value.

  In such a method, since a comparative evaluation value can be obtained by comparing the sizes of the feature points, the search time for the similarity code can be greatly shortened, which is about 8 compared with the case of comparing each pixel. It becomes possible to make it 1 /.

  However, in this case, the innermost circumference has a weight 128 times that of the outermost circumference, and the accuracy on the inner circumference side, particularly the center alignment accuracy, has a great influence, and a high performance alignment servo mechanism is required. Therefore, as shown in (3) of FIG. 3, it is possible to reduce the weight difference between the inner and outer circumferences and shorten the comparison time by mainly performing weighting for comparing the magnitudes of only the upper 4 bits. become.

  In particular, as will be described later in detail, in order to absorb the discrepancy due to the difference in eye inclination with respect to the polar sensor unit, when comparing iris codes, for example, +/− 10 °, that is, about +/− 7 pixels, start comparison. It is possible to take a method such as shaking and comparing, and identifying an individual with the most similar result.

  When such processing is performed by the microcomputer in the iris discriminating device or the software on the host side, in general, an operation of checking for coincidence / non-coincidence for each bit and multiplying by weighting in the case of non-coincidence Must be repeated for the number of analysis bands (8) × the number of feature points in the circumferential direction (256).

  In such a method, the amount of calculation is considerably increased, and an extremely high-speed arithmetic processing device is required. As one method for dealing with this, as described above, weighting to the power of 2 as shown in (3) of FIG. 3 and (4) of FIG. This shortens the comparison time and reduces the burden on the arithmetic processing unit.

  FIG. 4 shows a schematic device configuration in the case of performing iris identification using a hardware circuit. The apparatus shown in FIG. 1 performs parallel-serial conversion on an iris information sensor 41 having the polar coordinate sensor unit as described above, a nonvolatile memory 42 for storing iris feature extraction codes in advance, and an output of the nonvolatile memory 42. A PS conversion circuit 43 and an exclusive OR circuit 44 for comparing the iris code supplied from the iris information sensor 41 with the iris code supplied from the PS conversion circuit 43 are provided.

  4 also includes an accumulator 47 for accumulating the output of the exclusive OR circuit 44, a weight setting circuit 46 for setting a weight corresponding to the radial position in the accumulator 47, and this weight setting circuit 46. Is provided with a radius count / selector 45 for giving a signal indicating the radius position.

  The apparatus of FIG. 4 further includes a comparator 49 that compares the comparative evaluation value obtained by the integrator 47 with a reference value supplied from the determination reference circuit 48.

  In the apparatus of FIG. 4, an imaging device including an iris information sensor 41 captures image light from an iris region of an eye such as an individual to be determined and generates a corresponding iris code. On the other hand, the iris code registered in advance in the nonvolatile memory 42 is converted into serial code data by the PS conversion circuit 43 and supplied to the exclusive OR circuit 44. The exclusive OR circuit 44 performs an exclusive OR operation for each bit corresponding to the iris code from the polar coordinate sensor 41 and the registered iris code from the non-volatile memory 42. For example, if there is a mismatch, a signal “1” is output. If they match, a “0” signal is output. These signals are supplied to the integrator 47.

  The radius count / selector 45 generates a signal indicating the radial position of each bit of the iris code output from the iris information sensor 41 in synchronization with the reading of the iris code of the iris information sensor 41. A signal indicating the radial position is supplied to the weight setting circuit 46. The weight setting circuit 46 outputs a signal indicating a greater weight toward the inner peripheral portion as described above according to the radial position indicated by the input signal and supplies the signal to the integrator 47.

  The accumulator 47 multiplies a signal value indicating inconsistency input from the exclusive OR circuit 44, for example, “1” and the weight value input from the weight setting circuit 46, and integrates them. The exclusive OR circuit 44 outputs, for example, a signal value “0” when the bit of the iris code from the iris information sensor 41 matches the corresponding bit of the iris code from the nonvolatile memory 42. The accumulator 47 accumulates the weighted values according to the radial positions only when there is a mismatch.

  At the time when the calculation by the exclusive OR circuit 44 and the integration by the integrator 47 are performed on the data from all the pixels of the iris information sensor 41, the integrator 47 outputs the comparative evaluation value of the person to be identified. .

  Therefore, the comparator 49 compares the comparison evaluation value output from the accumulator 47 with the reference value supplied from the determination reference circuit 48. If the comparison evaluation value is equal to or less than the reference value, the same person is determined. can do. It should be noted that the reference value supplied from the determination reference circuit 48 can be conveniently selected, for example, from several values prepared in advance or supplied from the outside. As a result, it is possible to set the correlation degree of the iris code to a desired value and appropriately set the person rejection rate and the other person acceptance rate.

  In the above configuration, the integrator 47 or the like may be configured as a digital circuit, or may be realized as an analog circuit. FIG. 5 shows a configuration in which the circuit portion including the integrator 47 of FIG. 4 is realized by an analog circuit. In the circuit configuration of FIG. 1, current sources I1, I2, I3,..., I8 having current values corresponding to weights determined by radial positions, and transistor switches S1, S1 connected in series with these current sources. , S8 are provided. The series circuit of each current source I1, I2,... And the transistor switches S1, S2,... Is connected at both ends together, and is turned on when there is a mismatch with a power line (not shown). Is connected to one of the current terminals, the source or the drain.

  The gate electrodes of the transistor switches S1, S2, S3,..., S8 have radius selection signals rADRS1, rADRS2, rADRS3,... For turning on the corresponding transistor switches when reading the analysis band of each radius. , RADRS8 is supplied. Therefore, each of the transistor switches S1, S2, S3,..., S8 is turned on while reading out the pixels in the analysis band at each radial position from the inner peripheral portion to the outer peripheral portion of the polar coordinate sensor portion.

  The circuit in FIG. 5 further includes a reset MOS transistor 52 connected in series with the MOS transistor 51 and a capacitor (C) 53 connected in parallel with the reset MOS transistor 52. Further, the circuit of FIG. 5 includes a comparator 54 that receives a signal corresponding to the voltage across the capacitor 53 at one terminal and receives a signal indicating a determination level from the determination reference circuit at the other input, a transmission gate and an inverter. And a latch circuit 55 configured by the above.

  Note that a signal rADRS0 that becomes active when reading out the edge detection pixels arranged adjacent to the inner peripheral side of the effective pixel area of the polar coordinate sensor portion of the iris information sensor is applied to the gate electrode of the reset MOS transistor 52 as a reset signal. As a supply. Further, as a control signal for each transmission gate of the latch circuit 55, a signal rADRS9 that is active when reading out other edge detection pixels provided on the outer periphery of the effective pixel area of the polar sensor unit is supplied. . The latch circuit 55 performs the same operation as that of the delay flip-flop (D-FF).

  In the circuit of FIG. 5, for example, when a pixel in the innermost analysis band of the polar sensor unit is read, the radius selection signal rADRS1 is turned on and the transistor switch S1 is conductive. Therefore, for example, when a signal indicating mismatch from the exclusive OR circuit 44 of FIG. 4 is applied to the gate of the transistor 51, the transistor 51 is turned on, and the current determined by the current source I1 causes the transistor switch S1 and the transistor 51 to be turned on. Through the capacitor 53, and the capacitor 53 accumulates charges corresponding to the magnitude of the current. In this way, when the comparison result becomes inconsistent, a current having a magnitude determined by the current source I1 flows, and the charge corresponding to the magnitude of the current is accumulated in the capacitor 53.

  In this way, reading is sequentially performed from the inner analysis band to the outer analysis band of the polar coordinate sensor unit, and the magnitude determined by the current source at each radial position in response to a mismatch occurring during the reading. This current flows through the transistor 51, and a charge corresponding to the current is accumulated in the capacitor 53.

  In this way, when reading of all the pixels is completed, the charge corresponding to the comparative evaluation value, that is, the voltage is accumulated in the capacitor 53. The voltage indicating the comparative evaluation value is compared with the voltage indicating the determination level supplied from the determination reference circuit in the comparator 54, and the comparison result is sent to the latch 55 by the radius selection signal rADRS9 for selecting the edge detection pixel on the outer periphery of the effective pixel. Is taken in. Therefore, the output of the latch circuit 55 indicates the determination result as to whether or not they are the same person. Before accumulating the accumulated charge in the capacitor 53, the reset CMOS transistor 52 is turned on by the radius selection signal rADRS0 for selecting the inner edge detection pixel in the effective pixel area, and the charge in the capacitor 53 is discharged and compared. Reset the evaluation value.

  6A and 6B show a schematic configuration of an iris information sensor used in the iris discriminating apparatus according to the present invention. The iris information sensor shown in the figure includes a polar coordinate sensor unit 10a integrated as a basic component on a sensor chip substrate (hereinafter simply referred to as a substrate) 61 such as a semiconductor. The polar coordinate sensor unit 10a includes a plurality of photoelectric conversion pixels 62 arranged in a polar coordinate form with the origin o of polar coordinates as the center. The photoelectric conversion pixel 62 is formed of a photodiode, for example, and is used to capture an iris image of the eye.

  A quadrant photodiode (PD) sensor 10c for detecting a position error is formed in a central area having a predetermined radius from the origin o of polar coordinates. The PD sensor 10c for position error detection is composed of, for example, a photodiode divided into four fan-shaped regions having an apex angle of 90 ° with the origin o as a vertex.

  Various circuit elements for reading and processing an image signal from the polar coordinate sensor unit 10a are formed outside the polar coordinate sensor unit 10a. For example, a pair of strip-shaped portions indicated by reference numeral 63 are read potential holding capacitors for temporarily storing a read image signal from the polar sensor unit 10a, and the pair of capacitors corresponds to one pixel. The read potential holding capacitors 63 are provided in a number that can hold the image charges from one round of pixels at one radial position of the polar coordinate sensor unit 10a. The pair of capacitors includes, for example, one capacitor holding a potential immediately after resetting the pixel, and the other capacitor holding a potential of the pixel after receiving image light, that is, a potential after charging. The difference between the potentials of both capacitors is used as a readout signal from the pixel.

  Reference numeral 64 indicates an output selection processing circuit in which a switching circuit including a MOS transistor array for outputting an image signal read out via the read potential holding capacitor 63 to the outside is arranged.

  FIG. 6B shows a part of the photoelectric conversion pixel 62 extracted from the polar coordinate sensor unit 10a of FIG. 6A. As shown in FIG. 6B, the photoelectric conversion pixels 62 are arranged so as to form, for example, eight analysis bands with the origin o of polar coordinates as the center. For example, the pixels 62a constituting the innermost analysis band are arranged on a predetermined radius centered on the polar coordinate pole o. In addition, the pixel 62b is arranged along the circumference of the second analysis band outside the innermost analysis band, and the pixel 62c is arranged along the circumference in the further analysis band. Pixels are sequentially arranged along the outer analysis band. These pixels 62a, 62b, 62c,... Constitute an effective pixel group for imaging an iris pixel and generating an iris code. Note that an edge detection pixel group 65 for detecting an inner peripheral edge of an iris image projected on the polar sensor unit 10a is arranged in the inner peripheral portion of these effective pixel group regions. Further, an outer edge detection pixel group (not shown) is arranged on the outer periphery of the effective pixel area.

  Each effective pixel 62 has a shape in which the width of the pixel is large in the vicinity of the central portion in the radial direction, that is, in the vicinity of the central portion of each analysis band, and the width of the pixel decreases as the distance from the central portion in the radial direction increases. It has a substantially rhombus shape so that weighting is performed so that the pixel output is maximized near the center in the radial direction of the pixel. The innermost edge detection pixel 65 and the outermost edge detection pixel (not shown) have a substantially triangular shape.

  In the iris information sensor 61 of FIG. 6, reading of the iris image signal from each pixel 62 of the polar coordinate sensor unit 10a is performed from the innermost peripheral analysis band pixel 62a from the pixel at the predetermined start position 66. The pixels for one circumference are read out, and then the pixels 62b in the second analysis zone are read out along the circumferential direction. Thereafter, the pixels for one round at each radial position are read out in the same manner, and the pixels at the outermost circumference are read out to complete one reading. A substantially spiral arrow in FIG. 6A shows an example of this reading process.

  Actually, the readout charges from the pixels for one round at each radial position are simultaneously read out and accumulated in the readout potential holding capacitor 63, and the pixel signal in the circumferential direction is output by the output selection circuit 64 or the like. Output sequentially.

  When the iris information sensor reads the iris information of the eye and performs iris identification, the readout start position 66 is read from the predetermined start position, that is, the pixel position indicated by (1) in FIG. Thereafter, it is convenient to read out the iris image information from the pixels before and after the start position 66 and perform iris identification. That is, in order to absorb the error of the comparative evaluation value due to the difference in the eye tilt between the iris information sensor 61 and the person to be recognized, when comparing the iris code with previously registered iris code data, for example, +/− 10 It is convenient to perform the comparison by shifting (shifting) the comparison start position to about 0 °, for example, +/− 7 pixels. It is advantageous to perform sequential reading by shifting the reading start position and comparing with pre-registered iris code data, and using the read iris code with the lowest evaluation value, that is, the lowest evaluation value for personal identification It is.

  For example, as shown in FIG. 6B, the pixel of the polar coordinate sensor unit 10a is first read from the pixel at the reading start position 66 indicated by the numeral (1). Next, the readout start position, that is, the comparison start position is shifted to the position indicated by (2) in FIG. 6B, and the signal of the pixel of the polar sensor unit 10a is similarly read out from the pixel at this position and registered in advance. Compare with iris code data. Hereinafter, similarly, the reading start position is changed to (3), (4), (5),..., The iris codes are compared, and the lowest comparison evaluation value is adopted.

  In addition, when such a comparison start position is shaken to obtain a comparative evaluation value, it becomes a small value only in a small range including points with matching eye inclinations. Therefore, the comparison start value is sequentially read out, and once the comparison evaluation value falls below the determination value that can be determined to be the same person, or the comparison evaluation position is changed, the comparison evaluation value becomes the determination value. If this is the case, the following comparison can be omitted to shorten the comparison time. Therefore, it is desirable to perform comparison at first with a tilt of 0 °, and then read and compare from the start position shifted by +/− 1 pixel, +/− 2 pixel,.

  The reading and comparison operation of the iris code as described above can be performed by software using a microcomputer provided in the iris identification device or a host computer. In this case, the operation of confirming the coincidence / non-coincidence for each bit, and in the case of non-coincidence, multiplying and multiplying by the weight set in accordance with the radial position is the number of analysis bands (8) × circumferential direction It is necessary to repeat the number of feature points (256). Further, when the comparison operation is performed while sequentially shifting the comparison start position as described above, such an operation needs to be performed for each comparison start position.

  Further, reading and comparison can be performed by sequentially shifting the reading start position in the circumferential direction using the circuit shown in FIG. In this case, an image signal is read from the polar coordinate sensor 41 of FIG. 4 in advance from a predetermined reading start position, an iris code is generated, and comparison is performed by the comparator 49 as described above. Then, the reading start position from the polar coordinate sensor 41 is sequentially shifted to the left and right, and the iris image signal is read and the iris code is generated in the same manner, and the comparator 49 performs comparison. By such an operation, the iris code data having the lowest comparative evaluation value may be adopted to perform the iris identification.

  Next, FIG. 7 shows a configuration in which iris image signals are simultaneously read from a plurality of read start positions, iris codes are generated, and comparison determination is simultaneously performed.

  7 includes a polar coordinate sensor 71 having a pixel shift circuit 71a, a nonvolatile memory 72 that stores registered iris code data, a PS conversion circuit 73 that converts output data of the nonvolatile memory 72 into a serial signal, Exclusive OR circuits 74-1, 74-2, 74-3,..., 74- for comparing the iris code output in parallel from each polar coordinate sensor 71 with the registered iris code data from the nonvolatile memory 72. m. 7 also includes a plurality of sets of radius count / selector 75, weights provided corresponding to the exclusive OR circuits 74-1, 74-2, 74-3,..., 74-m. A setting circuit 76, an integrator 77, a determination reference generation circuit 78, and a comparator 79 are provided.

  In the circuit configuration of FIG. 7, the iris information sensor 71 has the same configuration as the iris information sensor 61 described previously with reference to FIG. Therefore, the iris information sensor 71 includes a polar coordinate sensor unit 10a, a read-out potential holding capacitor 63 that is arranged outside the polar coordinate sensor unit 10a and holds an image signal potential for one round, and a MOS transistor array 64. Yes. Accordingly, the pixel charge of each analysis band of the polar coordinate sensor unit 10a is read in parallel to the readout potential holding capacitor 63 for one analysis band. Therefore, the pixel charges read in parallel can be taken out in parallel from different read start positions by the pixel shift circuit 71a constituted by the MOS transistor array 64 and the like, and the corresponding iris codes can be generated. it can.

  The iris codes of a plurality of systems generated based on the image signals read from the respective read start positions in this way are exclusive OR circuits 74-1, 74-2, 74-3,. An exclusive OR operation with the registered iris code data supplied from the non-volatile memory 72 is performed. Each of the exclusive OR circuits 74-1, 74-2, 74-3,..., 74-m performs an exclusive OR operation on the iris code and the registered iris code data sequentially read from each reading start position. If both match, “0” is output, and if they do not match, “1” is output.

  Accordingly, in the accumulator 77, the weight setting circuit 76 generates weighting data corresponding to the radius position designated by the radius count / selector 75, as described above with reference to FIG. The value is multiplied by the data “1” in the case of the mismatch in the integrator 77 and integrated to generate a comparative evaluation value. The comparison evaluation value generated in this way is compared with a value indicating the determination criterion supplied from the determination criterion generator 78 in the comparator 79, and a determination result is output.

  Such processing is performed for the outputs of the exclusive OR circuits 74-1, 74-2, 74-3,..., 74-m, and the determination is based on read signals from a plurality of read start positions. The results are displayed and output simultaneously by a plurality of comparators 79.

  By using such a circuit configuration, it is possible to compare the iris image signal read from a plurality of read start positions, and thus the iris code, with the registered iris code data in parallel. Therefore, the influence on the comparative evaluation value due to the difference in the inclination of the eyes is removed, and it is possible to perform accurate iris identification at a high speed.

  FIG. 8 shows a schematic configuration of an iris identification apparatus according to another embodiment of the present invention. The apparatus shown in the figure shows a configuration used when, for example, face-to-face or peep-type iris detection is performed. In the apparatus configuration of FIG. 8, for example, when the iris sensor is looked into from a predetermined hole or the recognition target person positions the face at a position such as a predetermined frame, the iris sensor is within a predetermined narrow range. The eye of the person to be recognized is positioned at a predetermined distance from the iris sensor. In such a case, instead of performing preprocessing such as iris positioning by a wide-angle camera as previously described with reference to FIG. 1, the relative angle of the VAP (vertical angle variable prism) 8a or a plurality of lenses is relatively different. The parallel translation can be used to simplify the configuration. For example, in FIG. 8, an iris image can be obtained by controlling only a zoom camera including an optical system including the apex angle variable prism 8a and the zoom lens 8b, an iris acquisition unit 9 including an iris sensor, and the like.

  In FIG. 8, 7c is a pan / tilt motor for driving the apex angle variable prism 8a, and 7d is a zoom / focus motor.

  Further, the controller 81 does not require the control part of the wide-angle camera unlike the iris acquisition controller 6 in FIG. 1, and is simplified and performs drive control of the apex angle variable prism 8a and the zoom lens 8b. .

  8 has a memory 82 for storing a registered iris code for comparison, and a comparison circuit 83 for comparing the iris code detected by the iris acquisition unit 9 with the registered iris code stored in the memory 82. Further, a discrimination value setting circuit 84 for setting the discrimination judgment level of the comparison circuit 83, that is, the correlation degree of the iris code is provided. The judgment value setting circuit 84 is constituted by, for example, a register for storing a judgment value, and writes some values prepared in advance to the register from the outside of the apparatus or inside the apparatus, and sets the identification judgment level. To do.

  In addition, an encryption circuit 85 is provided so that data indicating the determination result of the iris identification can be encrypted and supplied to the outside.

  In the configuration of FIG. 8, for example, the iris acquisition unit 9, the controller 81, the memory 82, the comparison circuit 83, the determination value circuit 84, the encryption circuit 85, and the like are integrated as one integrated circuit device 80, thereby simplifying the device configuration. be able to. Moreover, the determination level of iris identification can be set to any desired value. Furthermore, since the iris code is not output to the outside, the confidentiality of the iris code is maintained, and a safer identification device can be realized. Therefore, a high-performance iris discriminating device is provided with a simple device configuration.

  The present invention can be applied to an apparatus such as an ATM that needs to perform personal identification with high reliability and high convenience, and has a device configuration such as an iris information acquisition apparatus and an iris identification apparatus in such an apparatus. It is possible to simplify and achieve high identification accuracy.

It is a block diagram which shows the structural example of the iris information acquisition apparatus used for the iris identification device concerning one Embodiment of this invention. It is a block diagram which shows the structure of the outline of the iris acquisition part in the iris information acquisition apparatus of FIG. It is explanatory drawing which shows the iris information sensor used for the iris identification device concerning this invention, and the weighting method of each pixel. It is a block diagram which shows the schematic structure of the iris identification device concerning one Embodiment of this invention. FIG. 5 is a block circuit diagram showing a configuration of an analog integrator that can be used in the iris identification device of FIG. 4 or the like. It is explanatory drawing (a) which shows schematic structure on the chip | tip of the iris information sensor concerning this invention, and reading procedure explanatory drawing (b) which takes out and shows a part of polar coordinate sensor part of an iris information sensor. It is a block diagram which shows the schematic structure of the iris identification device concerning another embodiment of this invention. It is a block diagram which shows the schematic structure of the iris identification device concerning another embodiment of this invention.

Explanation of symbols

1a, 1b Wide-angle camera 6 Iris acquisition controller 7a Zoom / focus motor 7b Steering motor 8 Zoom lens optical system 9 Iris acquisition unit 10 Iris information sensor 10a Polar sensor unit 10c Position error detection PD sensor 11 Iris inner diameter detection circuit 12 Iris outer diameter Detection circuit 13 Light emitting diode 14 High pass filter 15 Weighted moving average circuit 16 Binary circuit 17 Latch circuit 18 Timing generator 19 Driver 31 Photoelectric conversion pixel 33 Radial pixel group 41, 71 Iris information sensor 42, 72 Non-volatile memory 45, 73 PS Conversion circuit 44, 74-1, 74-2, ..., 74-m Exclusive OR circuit 71a Pixel shift circuit 45, 75 Radius count / selector 46, 76 Weight setting circuit 47, 77 Accumulator 48, 78 Judgment reference circuit 49, 79 Comparator 61 Sensor chip substrate 62 Photoelectric conversion pixel 63 Capacitor for reading potential holding 64 Output selection processing circuit 65 Edge detection pixel group 66 Reading start position

Claims (9)

A photoelectric conversion pixel group arranged in polar coordinates, and the photoelectric conversion of image light from an iris region of an eye so that a center of an iris image formed on the pixel group coincides with a pole of the polar coordinate A polar coordinate sensor unit that forms an image on the pixel group, sequentially scans each photoelectric conversion pixel of the photoelectric conversion pixel group, and reads an iris image signal;
A feature extraction code generator for generating an iris feature extraction code based on the read iris image signal;
A comparison unit that compares the iris feature extraction code generated by the feature extraction code generation unit with a previously registered iris feature extraction code to generate a comparative evaluation value, the comparison evaluation value being the polar coordinate sensor unit A comparison unit that generates a comparative evaluation function having a greater weight toward the inner periphery of
The iris identification device is characterized in that the iris evaluation is performed by comparing the comparative evaluation value with a predetermined reference value.   An exclusive OR operation is performed on the iris feature extraction code generated by the feature extraction code generation unit and the previously registered iris feature extraction code for each pixel, and the mismatched portion is weighted according to the radial position of each pixel. The iris identification device according to claim 1, wherein the comparison evaluation value is generated by integrating the values.   2. The iris identification device according to claim 1, wherein the photoelectric conversion pixel group of the polar coordinate sensor unit is divided into a plurality of concentric analysis bands and has the same number of pixels in the circumferential direction.   Among the pixel groups arranged along each radial direction, the iris feature extraction code is such that the pixels arranged on the inner peripheral side are the most significant bit side, and the pixels arranged on the outer peripheral side are the least significant bit side. So that each pixel arranged along each radial direction has a weight corresponding to each bit of the binary number, and is registered in advance for each feature extraction data from the pixel group arranged along each radial direction 4. The iris identification apparatus according to claim 3, wherein the iris identification is performed by comparing the size of the iris feature extraction code with the corresponding feature extraction data.   5. The iris identification according to claim 4, wherein among the iris feature extraction data from the pixel group arranged along each radial direction, iris identification is performed using only some of the bits from the most significant bit side. Iris identification device.   The iris image signal is read out from the pixel at a predetermined reading start position in the circumferential direction of the polar sensor along the innermost analysis band, and then along the analysis band outside the analysis band. 2. The iris identification device according to claim 1, wherein reading for one round is performed from the reading start position, and then reading is sequentially performed toward the outer circumferential side.   After reading out the iris image signal for all the pixels from the predetermined readout start position, the readout start position is sequentially shifted in the circumferential direction to perform readout, and the iris feature extraction code generated from the readout image signal 7. The iris identification apparatus according to claim 6, wherein iris identification is performed using an iris feature extraction code generated from an image signal read from a read start position that most closely matches a previously registered iris feature extraction code. .   In the process of performing the reading by sequentially shifting the reading start position from the predetermined reading start position, once a comparative evaluation value that can be determined as the same person is obtained, the subsequent reading and comparison are omitted. The iris identification device according to claim 7. A plurality of iris feature extraction codes generated from iris image signals read out in parallel with each of a predetermined number of pixels consecutive in the circumferential direction being read out in parallel as compared with previously registered iris feature extraction codes The comparison and integration circuit is provided, and among the comparison evaluation values obtained by these comparison and integration circuits, the iris evaluation is performed using the comparison evaluation value that best matches. Iris identification device.

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