JP4508842B2 - Iris information sensor - Google Patents

Description

  The present invention relates to an iris information sensor, and in particular, in an area sensor in which pixels are arranged in polar coordinates, that is, a polar coordinate sensor, a position error detection sensor used when the center of an iris image of an eye coincides with the pole of a polar coordinate sensor. The detection range is expanded so that an iris image can be reliably formed on a polar sensor.

  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. is doing.

  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 position error between the center of the iris image formed on the image sensor by the center position error detection means and the polar coordinate pole of the image sensor is received by the reflected light from the eye surface. A servo operation is performed to match the center of the iris image with the polar coordinate pole of the image sensor by the optical axis shift of the image pickup lens or the like by the error signal obtained by the position error detecting means. As a result, the center of the iris image and the polar coordinate pole of the imaging sensor can be matched, and the iris image can be accurately captured using the polar coordinate sensor.

In particular, as a conventional position error detection means, a position error detection photodiode (PD) divided into four is formed at the center of a photoelectric conversion pixel group arranged in polar coordinates, and each of the position error detection PDs is formed. A position error detection signal was obtained based on the amount of light received by the element.
JP 2000-36036 A

  However, in such a conventional iris information sensor, the position error detection quadrant photodiode is disposed only in the central portion of the photoelectric conversion pixels arranged in the polar coordinate form, so that the center of the iris image and the polar coordinates of the imaging sensor are arranged. When positioning servo is applied in order to align the poles of the image sensor, the iris of the position of the position error detection PD is detected unless the iris image is first formed at substantially the center of the image sensor by some means. Because it does not enter, the positioning servo cannot be pulled in.

  That is, in the conventional iris information sensor, the pull-in range of the alignment servo has to be narrowed. However, if the pull-in range is narrow, for example, the position of the eyes is shifted due to a slight movement of a person, the imaging position of the iris image is shifted, and the alignment servo is disengaged. Further, when the center of the iris image is deviated from the center of the polar coordinate sensor, there is a disadvantage that the center of the iris image cannot be drawn into the center of the polar coordinate sensor.

  Accordingly, an object of the present invention is to provide an alignment servo between the center of an iris image and the center of a polar coordinate sensor in a polar coordinate sensor having photoelectric conversion pixel groups arranged in a polar coordinate shape in view of such problems in the prior art. In addition to increasing the pull-in range, the position can be quickly aligned even when the misalignment between the center of the iris image and the pole of the polar coordinate sensor is large.

According to one aspect of the present invention, an imaging sensor unit including a plurality of photoelectric conversion pixels arranged in a polar coordinate pattern excluding a central area having a predetermined radius from the origin, and the eye surface disposed in the central area. From a plurality of photoelectric conversion elements for determining the direction and size of an error between the center of an iris image formed on the image sensor unit by receiving reflected light from the image and the polar coordinate pole of the image sensor unit The first position error detection unit and the photoelectric conversion pixels are dispersed in the area of the gap between the photoelectric conversion pixels in the area where the photoelectric conversion pixels are arranged, and the reflected light from the surface of the eye in the area where the photoelectric conversion pixels are arranged A first photoelectric conversion element comprising a plurality of photoelectric conversion elements for determining the direction and magnitude of an error between the center of an iris image formed on the imaging sensor unit and receiving the polar coordinate pole of the imaging sensor unit. Position includes an error detecting unit, of said first position error detector plurality of photoelectric conversion elements constitute the first four-division sensor divided into four regions whose vertices the origin, the The plurality of photoelectric conversion elements of the second position error detection unit constitute a second four-divided sensor divided into four regions having the origin as a vertex, and the four regions of the second four-divided sensor are Each of the images from the iris region of the eye corresponds to the four regions of the first four-divided sensor and uses the direction and magnitude of the error obtained by the first and second position error detectors. Light is drawn into and held in the imaging sensor unit so that the center of the iris image formed on the imaging sensor unit and the polar coordinate pole of the polar sensor coincide with each other, and the photoelectric of the imaging sensor unit is formed. Iris image by sequentially scanning conversion pixels Iris information sensor is provided, characterized in that reading the issue.

  In this case, the position error detection signal indicating the direction and magnitude of the error obtained by the first and second position error detectors is weighted with a predetermined weight and then combined and used to When the image light from the iris region is drawn into and held in the imaging sensor unit so that the center of the iris image formed on the imaging sensor unit and the polar coordinate pole of the polar coordinate sensor coincide with each other, the image light is imaged. Convenient.

According to still another aspect of the present invention, an imaging sensor unit composed of a plurality of photoelectric conversion pixels arranged in a polar coordinate pattern excluding a central area having a predetermined radius from the origin, and disposed in the central area, A plurality of photoelectric conversions for obtaining the direction and magnitude of an error between the center of an iris image formed on the imaging sensor unit by receiving reflected light from the surface of the image and the polar coordinate pole of the imaging sensor unit A first position error detection unit composed of an element and a region in which the photoelectric conversion pixels are arranged are distributed and arranged in a gap region of the photoelectric conversion pixels, and a region from the surface of the eye in the region in which the photoelectric conversion pixels are arranged A plurality of photoelectric conversion elements for receiving reflected light and determining an error direction and magnitude between a center of an iris image formed on the imaging sensor unit and a polar coordinate pole of the imaging sensor unit; The second position error detection unit is arranged around the imaging sensor unit and receives reflected light from the surface of the eye and receives reflected light from the surface of the eye at a portion around the imaging sensor unit. Third position error detection comprising a plurality of photoelectric conversion elements for determining the direction and magnitude of the error between the center of the iris image formed on the image sensor unit and the polar coordinate pole of the image sensor unit A plurality of photoelectric conversion elements of the first position error detection unit constitute a first four-divided sensor divided into four regions having the origin as a vertex, and the second position The plurality of photoelectric conversion elements of the error detection unit constitute a second four-divided sensor divided into four regions having the origin as a vertex, and the plurality of photoelectric conversion elements of the third position error detection unit are the origin The third 4 divided into four areas with vertices The four regions of the second four-divided sensor correspond to the four regions of the first four-divided sensor, and the four regions of the third four-divided sensor respectively , Corresponding to the four regions of the first four-divided sensor, using the direction and magnitude of the error obtained by the first, second and third position error detectors together, from the iris region of the eye Image light is drawn and held in the image sensor unit so that the center of the iris image formed on the image sensor unit coincides with the polar coordinate pole of the polar coordinate sensor, and the image sensor unit forms an image. An iris information sensor is provided that sequentially scans the photoelectric conversion pixels and reads out an iris image signal.

  In this case, signals obtained by combining the position error detection signals indicating the direction and magnitude of the error obtained by the first, second, and third position error detection units after weighting each with a predetermined weight are used. Then, the image light from the iris region of the eye is drawn into and held in the imaging sensor unit so that the center of the iris image formed on the imaging sensor unit matches the polar coordinate pole of the polar coordinate sensor. It is convenient to image.

Incidentally, the photoelectric conversion pixels, respectively, for the radial weighting in the photoelectric conversion pixel has a different shape width in the circumferential direction in accordance with the radial position, circular circumferential width each photoelectric Conveniently, the center of the radial position in the transformed pixel is larger than the ends of the radial position.

  In addition, it is convenient that the plurality of photoelectric conversion elements of the second position error detection unit have a complementary shape to the shape of the gap between the photoelectric conversion pixels.

  According to the present invention, in addition to providing the position error detection unit (first position error detection unit) at the center of the polar coordinate sensor, the photoelectric conversion pixel of the polar coordinate sensor is arranged in the region where the photoelectric conversion pixel is arranged. The second position error detection photodiode is also arranged in the gap, and the position error detection is performed together with the photodiode in the central portion, thereby widening the pull-in range of the positioning servo of the iris information sensor and pull-in. Can be ensured. Also, with such a configuration, the alignment servo pull-in operation can be speeded up.

  In addition to providing a PD for position error detection in the center of the polar coordinate sensor, the third position error detection is performed in an area from the outside of the area where the photoelectric conversion pixels of the polar coordinate sensor are arranged to the edge of the integrated circuit chip. By arranging the PD for use, the pull-in range of the alignment servo can be expanded and the pull-in speed can be increased while effectively using the area on the integrated circuit chip.

  Further, in addition to the position error detection PD provided in the central part of the polar coordinate sensor, the second position error detection PD arranged in the pixel area of the polar coordinate sensor and the third position error arranged around the polar coordinate sensor. By forming the detection PD together, the alignment servo pull-in range is widened, and quick and reliable alignment is possible regardless of the positional relationship between the center of the iris image and the center of the polar coordinate sensor. It becomes possible to do. As a result, as long as the light spot of corneal reflection enters the end of the sensor chip, it is possible to easily draw and hold the light spot, that is, the center of the iris image to the center of the polar sensor.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of an iris information sensor according to an embodiment of the present invention. The iris information sensor shown in FIG. 1 includes a polar coordinate sensor unit 3 integrated as a basic component on a sensor chip substrate (hereinafter simply referred to as a substrate) 1 such as a semiconductor. The polar coordinate sensor unit 3 includes a plurality of photoelectric conversion pixels 5 arranged in a polar coordinate form with an origin o of polar coordinates as a center. However, no photoelectric conversion pixel is arranged in the central area 7 having a predetermined radius from the origin o of the polar coordinates. The photoelectric conversion pixel 5 is made of, for example, a photodiode, and is used to capture an iris image of the eye.

  In the center area 7, a quadrant photodiode (PD) sensor 9 for detecting a position error is formed. The PD sensor 9 for position error detection is composed of, for example, a photodiode divided into four fan-shaped regions whose apex angle is 90 ° with the origin o as a vertex. In the present embodiment, a square substrate is used as the substrate 1, and the four-divided PD sensor 9 is divided along the diagonal line of the substrate 1. Of course, the quadrant PD sensor 9 may be divided along the lines parallel to the respective sides of the substrate 1, that is, the horizontal and vertical lines in FIG.

  Various circuit elements for reading out and processing the image signal from the polar coordinate sensor unit 3 are formed outside the polar coordinate sensor unit 3. For example, a pair of strip-shaped portions indicated by reference numeral 11 are read potential holding capacitors for temporarily storing read image signals from the polar coordinate sensor unit 3, and the pair of capacitors corresponds to one pixel. The read potential holding capacitor 11 is provided in a number that can hold the image charges from the pixels for one round at one radial position of the polar sensor unit 3. 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.

  The wedge-shaped region 13 between each pair of read potential holding capacitors is used in combination with the above-described 4-divided PD sensor 9 for position error detection, as will be described in detail later. A part of the second position error detection PD sensor for detecting a position error between the center of the iris image formed on the pole 3 and the polar coordinate pole of the polar sensor is formed.

  Reference numeral 15 denotes 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 11 to the outside is arranged. However, the operation of these circuits is not a part directly related to the present invention, and a detailed description thereof will be omitted.

  A third center position error detecting quadrant PD sensor 17 is formed in a vacant region from the outside of the output selection processing circuit 15 to the peripheral edge portion of the substrate 1. The third quadrant PD sensor 17 for position detection is formed using all or part of the empty area of the substrate 1 outside the area including the polar coordinate sensor unit 3 and the related image reading circuit. Since the polar sensor unit 3 and related circuits are generally formed in a circular shape and the substrate 1 of the LSI chip is rectangular, a position error detection PD sensor is formed by utilizing the gap between the two. As will be described, the area on the substrate 1 can be used effectively and the pull-in range can be further expanded.

  A second position error detection PD sensor 19 is formed in the gap between the pixels 5 of the polar coordinate sensor unit 3. That is, as partially shown in FIG. 2, the second position error detection PD sensor 19 is formed so as to fill a region between the regions 5a in which each pixel is formed. Each position error detection PD sensor 19 has a triangular shape, two of which face each other to form a substantially rhombus shape, and fill a rhombus region between the photoelectric conversion pixels 5 of the polar coordinate sensor unit 3. Each position error detection PD sensor 19 has a triangular shape, which is for arranging wiring and other elements such as a pixel readout reset transistor. Therefore, each position error detecting PD sensor 19 can be formed in a diamond shape if there is no problem in wiring or the like.

  Each of the PDs of the second position error detection PD sensor 19 corresponds to the division of the first position error detection quadrant PD sensor 9, and the apex angle of 90 ° with the polar coordinate origin o as the apex. Those in the fan-shaped range are connected together by wiring or the like (not shown) to form a four-divided sensor.

  Further, as described above, the photodiode 13 formed in a wedge shape between the read potential holding capacitor 11 (FIG. 1) can also be used as a PD sensor for detecting a position error. The photodiode 13 is configured to be connected together with the second position error detection PD sensor 19 arranged between the pixels of the polar coordinate sensor unit 3 to form a part of the second position error detection PD sensor. This is convenient. However, the photodiode 13 can be connected to the third position error detecting PD sensor 17 and used as a part of the third position error detecting PD sensor.

  FIG. 3 shows a configuration in the vicinity of each photoelectric conversion pixel 5 of the polar coordinate sensor unit 3. As shown in the figure, each photoelectric conversion pixel 5 of the polar coordinate sensor unit 3 has a substantially rhombus shape. As will be described later, for example, when the pupil diameter of the eyes is controlled by visible light and the number of pixels in the radial direction of the polar coordinate sensor unit 3 is minimized, the weighting in the radial direction is performed by the pixels themselves. This is because it is convenient to be able to do it. That is, in each pixel 5, the pixel width is large in the vicinity of the substantially central portion in the radial direction, and the pixel width decreases as the distance from the central portion in the radial direction decreases. Is weighted so as to increase. With such a configuration, for example, even if there is a subtle error in the division position of each ring due to a change in pupil diameter, or there is a slight steering error, that is, the center of the polar coordinate sensor unit 3 and the center of the iris image are located. Even if there is a slight deviation, it is possible to prevent an increase in the false rejection rate of identification.

  Then, as described above, the position error detection PD 19 is formed in the gap portion of the substantially rhombic pixel 5. The position error detection PD 19 has a substantially triangular shape as described above, and the two position error detection PDs 19 are combined into a substantially rhombus, and a complementary rhombus gap between the pixels 5 is filled. Further, a pixel readout / reset transistor section 21 is formed outside the position error detection PD 19, for example, outside each pixel 5. The pixel readout / reset transistor unit 21 performs, for example, reading out an iris image signal and resetting the charge of the pixel 5. The pixel readout / reset transistor unit 21 is provided for each pixel. However, it is convenient to perform the pixel readout and reset operations simultaneously for each pixel having an equal radius, for example.

  In this embodiment, each unit shown in FIG. 3, that is, the pixel 5, two triangular position error detection PDs, and the pixel readout / reset transistor unit 21 together constitute one unit pixel unit. Such unit pixel units are arranged in polar coordinates as shown in FIG.

  FIG. 4 shows the overall configuration of an iris recognition system that uses the iris information sensor shown in FIG. 1, that is, an iris information acquisition apparatus. In FIG. 4, the iris recognition system first includes two wide-angle cameras 41 a and 41 b and a zoom camera 47. The wide-angle cameras 41a and 41b pick up images of the eyes of the person to be recognized by the CCDs 42a and 42b, and send image signals obtained by reducing noise in the picked-up signals to the iris acquisition controller 46 by the CDS circuits 43a and 43b. To do. The wide-angle cameras 41a and 41b control the CCD drivers 45a and 45b that drive and control the CCDs 42a and 42b based on the synchronization control signals generated by the control units 44a and 44b, and the processing operations of the CDS circuits 43a and 43b. Is controlling.

  The system of FIG. 4 also includes an iris acquisition controller 46. The iris acquisition controller 46 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 41 a and 41 b, and sends a signal or data indicating the specified result to the zoom camera 47. Output.

  Based on this three-dimensional position, the zoom camera 47 drives and controls the steering motor 47b to move the mirror 48c so that the imaging direction of the zoom camera 47 is directed toward the human eye. Further, the zoom camera 47 controls the zoom / focus motor 47a that drives the zoom lens optical system 48 to focus on the three-dimensional position of the human eye, and the iris image to be imaged is displayed on the sensor 40, for example, FIG. Control is performed to adjust the zoom amount so as to coincide with the imaging region of the iris information sensor shown. The iris acquisition unit 50 in the zoom camera 47 sends the position error and focus error information between the iris image captured by the sensor 40 and the sensor to the iris acquisition controller 46.

  The iris acquisition controller 46 servo-controls each part of the above-described camera system until information on the above-described 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 50.

  Note that the configuration of FIG. 4 includes a zoom lens optical system 48 that adjusts the size of the captured image so that the iris image to be imaged matches the imaging area of the sensor 40. However, it is obvious that the present invention does not use such a zoom lens optical system 48, 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 substantially matched with the imaging area of the sensor 40 without using a zoom lens. Further, in this case, the position of the eyes with respect to the camera is also restricted to a predetermined positional relationship, so that a configuration without using the wide-angle cameras 41a and 41b in FIG. 4 is possible.

  In the configuration of FIG. 4, the mirror 48c is moved so that the imaging direction of the zoom camera 47 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 configuration where the eye is aligned using the lens shift, when the sensor for detecting the lens position is used, the size and direction of the lens shift can be known from the output of the sensor. Can do. Therefore, for example, by using a voice guide or the like to prompt the person to be imaged to move the eye position in a desired direction, the lens shift amount can be controlled to be reduced or zero. . Accordingly, it is possible to use a relatively low cost optical component such as an imaging lens. In other words, it is not necessary to use an expensive imaging lens that maintains a high resolution even when the lens is shifted, and a low-cost imaging lens that can obtain a desired resolution only at a position where the lens shift is almost zero is used. It becomes possible to do.

  Here, the iris information received by the iris acquisition controller 46 from the iris acquisition unit 50 is an iris code binarized by the iris acquisition unit 50. The detailed configuration of the iris acquisition unit 50 will be described with reference to FIG.

  FIG. 5 shows a schematic configuration of an iris acquisition unit 50 using the iris information sensor 40 shown in FIG. The iris information sensor 40 may have the same configuration as that shown in FIG. 1, but the configuration is schematically shown in FIG. That is, the sensor 40 includes a polar coordinate sensor unit 3 composed of a plurality of photoelectric conversion pixels arranged in a polar coordinate form, a first position error detection unit 9 arranged in the central area 7 of the polar coordinate sensor unit 3, and a first not shown. 2 and / or a third position error detector. Each photoelectric conversion pixel of the polar coordinate sensor unit 3 may be configured by a photodiode, a CCD image sensor, or a MOS image sensor or other photoelectric conversion element.

  The apparatus of FIG. 5 also includes an LED (light emitting diode) 51 for illumination that is provided on the optical axis of the sensor 40 and illuminates the human eye with visible light. It is advantageous that the light emitting surface of the LED 51 is optically shifted from the light receiving surface of the sensor 40 so that the LED 51 can accurately illuminate human eyes. As the illumination means, in addition to the LED 51, an EL (electroluminescence) element and other arbitrary ones can be used.

  The apparatus shown in FIG. 5 further includes an iris inner diameter detection circuit 52. The iris inner diameter detection circuit 52 detects a boundary between the pupil and the iris in the radial direction in the picked-up 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, a level change is detected between the pixel arranged at the innermost circumference of the polar coordinate sensor unit 3, for example, the edge detection pixel at the innermost circumference of the triangle in FIG. 1, and the pixel arranged outside the pixel. Can be used to detect the boundary between the pupil and the iris.

  5 further includes an iris outer diameter detection circuit 53. The iris outer diameter detection circuit 53 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. For this edge detection, it is also possible to use pixels arranged on the outermost periphery of the polar coordinate sensor unit 3, in FIG. 1, the edge detection pixels on the outermost periphery of a triangle. Edge detection can be performed by changing the level of the detection signal with the arranged pixels.

  The iris outer diameter detection circuit 53 outputs a zoom error signal to the iris acquisition controller. The iris inner diameter detection circuit 52 detects the inner diameter of the iris as described above. The iris inner diameter detection circuit 52 generates a deviation between the detected inner diameter and the inner peripheral edge of the polar sensor unit 3, that is, a pupil diameter error signal, and the iris acquisition controller 46 To send.

  The iris acquisition controller 46 controls the brightness of the LED 51 so that this pupil diameter error signal disappears. That is, when the pupil diameter is larger than the inner peripheral edge of the polar sensor unit 3, the brightness of the LED 51 is increased, and when the pupil diameter is smaller than the inner peripheral edge of the polar sensor unit 3, the brightness of the LED 51 is decreased. Do. Of course, the brightness of the LED 51 may be directly controlled based on the pupil diameter error signal.

  As a result, the pupil diameter always matches the inner periphery of the polar coordinate sensor unit 3, and the outer periphery of the polar coordinate sensor unit 3 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 3.

  Therefore, the radial width of each pixel of the polar coordinate sensor unit 3 may be divided into necessary resolutions, for example, eight, and the iris code can be generated as it is using the imaging signal from the polar coordinate sensor unit 3.

  The imaging signal from the sensor 40 is sent to the high pass filter 54. The high-pass filter 54 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 46, respectively. As described above, the iris acquisition controller 46 controls the steering motor and zoom / focus motor in the zoom camera so that the iris to be imaged coincides with the center of the sensor 40 (polar coordinate sensor unit 3) and the outer diameter of the iris. Is matched with the outer peripheral edge of the sensor 40 (polar coordinate sensor unit 3), and the focusing process is performed.

  The timing generator 58 drives the driver 59 of the sensor 40 to perform scanning for outputting a pixel signal in the θ direction (rotation direction) for each ring. When fine imaging by the above-described feedback processing is performed and proper imaging is possible, an output signal from each pixel is sent to the bandpass filter 55 as an imaging signal. The band pass filter 55 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 56 generates an iris code obtained by binarizing the extracted signal using an inherent comparator. The iris code is sent to the iris acquisition controller 46 via the latch circuit 57. As described above, the iris acquisition controller 46 compares the iris code of each ring band with the iris code registered in advance in the host computer to perform 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, the sensor 40 having a large number of pixels in the radial direction does not need to be divided into each ring band, and the iris center is determined, so that an 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.

  Next, referring again to FIG. 1, the operation of each sensor 40 using the position error detection PD sensor will be described. As described above, the sensor 40 includes the first position error detection quadrant PD sensor 9 in the center, the pixel area has the second position error detection PD sensor 19 formed therein, and the polar coordinate sensor. A third position error detection PD sensor 17 is formed outside.

  Among these position error detection PD sensors, at least the first position error detection PD sensor 9 and the other second or third position error detection PD sensor 19 or 17 are used together to generate a steering error signal. Generate. Alternatively, the steering error signal may be generated using the first, second and third position error detecting PD sensors together. Outputs of the respective position error detection PD sensors are added through, for example, resistors each having a predetermined resistance value, and a combined steering error signal is generated. That is, each position error detection PD sensor is added with a predetermined weight, and a combined steering error signal is generated.

  However, in the sensor configuration of FIG. 1, the area of each position error detection PD sensor increases, that is, the photocurrent increases, from the polar coordinate pole o to the outer periphery. Therefore, even if weighting of each position error detection PD sensor is not performed, that is, even if the output of each position error detection PD sensor is added with the same gain, a larger steering error signal is obtained at the outer periphery, and the light of the iris image is obtained. When aligning the point with the center of the sensor, the servo gain increases as the outer circumference increases, enabling high-speed alignment. However, the gain of the output signal of each position error detection PD sensor may be adjusted according to the desired gain.

  The first position error detection PD sensor 9 provided at the center of the sensor 40 is mainly used for holding the image position after the alignment servo is pulled in, while the other second and / or third sensors. The position error detection PD sensor 19 and / or 17 can be used mainly for pulling in the alignment servo. Therefore, after the image position is drawn by the second and / or third position error detection PD sensors 19 and / or 17, the output of the first, second and third position error detection PD sensors is output. The weighting amount may be switched. For example, the gains of the outputs of the second and third position error detection PD sensors 19 and 17 are increased before the pull-in, and these are set to smaller values after the pull-in. Instead, the first position error detection PD The output gain of the sensor 9 may be increased. As a result, the iris image can be pulled in at a high speed and the image position can be held stably.

  It is convenient that the zoom camera is steered by such a position error detection PD sensor. That is, the light emitted from the LED 51 (FIG. 5) is reflected by the surface of the eye and received by each position error detection PD sensor. Since the position error detection PD sensor is divided into four parts around the pole o of the polar coordinates, the difference in the amount of light received in each divided segment part is sent to the iris acquisition controller as a steering error signal to perform steering control. Therefore, it is possible to perform servo control by directly feeding back the combined steering error signal generated by the position error detection PD sensor to the steering motor, and it is possible to reduce the size and performance of the system.

  In particular, by using the sensor shown in FIG. 1, the pull-in range is extremely wide, and as long as the light spot of the corneal reflection enters the end of the sensor chip, the light spot, and thus the center of the iris image of the eye, can be quickly obtained. It is possible to easily draw and hold the sensor center accurately.

  FIG. 6 shows an example of the positional relationship between the sensor 40 and the eyes in the apparatus of FIG. As shown in the figure, the illumination light 61 emitted from the illumination LED 51 is irradiated to the eye via the imaging lens 63. The pupil diameter of the eyes is controlled according to the intensity of the irradiated light. An iris image having a controlled pupil diameter is formed on the sensor 40 via the imaging lens 63. The reflected light 65 shows a state in which light reflected by the eyes from the LED 51 is irradiated on the photodiode.

  In the above-described configuration, the photodiodes of the position error detection PD sensor are arranged not only in the central area of the sensor 40 but also in the pixel area and / or the peripheral portion of the sensor. As a result, even if the light spot of the corneal reflection is not initially in the central area of the sensor 40, the center alignment can be quickly performed by the alignment servo.

  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 the operability of an iris information acquisition apparatus and an iris identification apparatus in such an apparatus is improved. It is possible to improve and enhance practicality.

It is explanatory drawing which shows the schematic structure on the chip | tip of the iris information sensor concerning one Embodiment of this invention. It is explanatory drawing which shows the detailed structure of the photodiode (PD) sensor part for position error detection of the iris information sensor shown by FIG. It is explanatory drawing which shows the structure of the outline of each pixel part of the iris information sensor of FIG. It is a block diagram which shows the schematic structure of the iris information acquisition apparatus using the iris information sensor concerning 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 mode of the use condition of the iris information sensor concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate 3 Polar coordinate sensor part 5 Photoelectric conversion pixel 7 Center area 9 1st position error detection PD sensor 11 Reading electric potential holding capacity 13 PD sensor area 15 Output selection processing circuit 17 3rd position error detection PD sensor 19 1st 2 Position error detection PD sensor 21 Pixel readout / reset transistor section 40 Iris information sensor 41a, 41b Wide angle camera 46 Iris acquisition controller 47 Zoom camera 47a Zoom / focus motor 47b Steering motor 48 Zoom lens optical system 48c Mirror 50 Iris acquisition 51 Light-emitting diode 52 Iris inner diameter detection circuit 53 Iris outer diameter detection circuit 54 High-pass filter 55 Band-pass filter 56 Binarization circuit 57 Latch circuit 58 Timing generator 59 Driver 61 Light 63 imaging lens 65 the reflected light 101 Iris

Claims (6)

An imaging sensor unit composed of a plurality of photoelectric conversion pixels arranged in a polar coordinate shape excluding a central area of a predetermined radius from the origin,
An error between the center of an iris image that is disposed in the central area, receives reflected light from the surface of the eye in the central area, and forms an image on the imaging sensor unit, and a polar coordinate pole of the imaging sensor unit. A first position error detection unit comprising a plurality of photoelectric conversion elements for obtaining a direction and a size;
In the region where the photoelectric conversion pixels are arranged, the pixels are dispersed and arranged in the gap region of the photoelectric conversion pixels. In the region where the photoelectric conversion pixels are arranged, the reflected light from the surface of the eyes is received and coupled to the imaging sensor unit. A second position error detection unit comprising a plurality of photoelectric conversion elements for determining the direction and magnitude of an error between the center of the iris image to be imaged and the polar coordinate pole of the imaging sensor unit;
Comprising
The plurality of photoelectric conversion elements of the first position error detection unit constitute a first four-divided sensor divided into four regions having the origin as a vertex,
The plurality of photoelectric conversion elements of the second position error detection unit constitute a second four-divided sensor divided into four regions having the origin as a vertex,
The four areas of the second quadrant sensor correspond to the four areas of the first quadrant sensor,
Using the direction and magnitude of the error obtained by the first and second position error detectors together, the image light from the iris region of the eye is centered on the iris image formed on the imaging sensor unit. The imaging sensor unit is drawn and held to form an image so that the polar coordinate poles of the polar sensor coincide with each other, and the photoelectric conversion pixels of the imaging sensor unit are sequentially scanned to read out an iris image signal. Iris information sensor.   An iris region of the eye using signals obtained by combining the position error detection signals indicating the direction and magnitude of the error obtained by the first and second position error detection units after being weighted with predetermined weights, respectively. Image light from the image sensor unit is drawn and held in the image sensor unit so that the center of the iris image formed on the image sensor unit coincides with the polar coordinate pole of the polar sensor. The iris information sensor according to claim 1. An imaging sensor unit composed of a plurality of photoelectric conversion pixels arranged in a polar coordinate shape excluding a central area of a predetermined radius from the origin,
An error between the center of an iris image that is disposed in the central area, receives reflected light from the surface of the eye in the central area, and forms an image on the imaging sensor unit, and a polar coordinate pole of the imaging sensor unit. A first position error detection unit comprising a plurality of photoelectric conversion elements for obtaining a direction and a size;
In the region where the photoelectric conversion pixels are arranged, the pixels are dispersed and arranged in the gap region of the photoelectric conversion pixels. In the region where the photoelectric conversion pixels are arranged, the reflected light from the surface of the eyes is received and coupled to the imaging sensor unit. A second position error detection unit comprising a plurality of photoelectric conversion elements for determining the direction and magnitude of an error between the center of the iris image to be imaged and the polar coordinate pole of the imaging sensor unit;
The center of an iris image that is arranged around the imaging sensor unit and receives reflected light from the surface of the eye at a portion around the imaging sensor unit and forms an image on the imaging sensor unit, and polar coordinates of the imaging sensor unit A third position error detection unit comprising a plurality of photoelectric conversion elements for determining the direction and magnitude of the error between the first and second poles;
Comprising
The plurality of photoelectric conversion elements of the first position error detection unit constitute a first four-divided sensor divided into four regions having the origin as a vertex,
The plurality of photoelectric conversion elements of the second position error detection unit constitute a second four-divided sensor divided into four regions having the origin as a vertex,
The plurality of photoelectric conversion elements of the third position error detection unit constitute a third four-divided sensor divided into four regions having the origin as a vertex,
The four areas of the second quadrant sensor correspond to the four areas of the first quadrant sensor,
The four areas of the third quadrant sensor correspond to the four areas of the first quadrant sensor,
An iris image in which image light from the iris region of the eye is imaged on the imaging sensor unit using the direction and magnitude of the error obtained by the first, second and third position error detection units together The center of the image sensor and the polar coordinate pole of the polar coordinate sensor are drawn and held in the imaging sensor unit to form an image, and photoelectric conversion pixels of the imaging sensor unit are sequentially scanned to read out the iris image signal. A featured iris information sensor.   A position error detection signal indicating the direction and magnitude of the error obtained by the first, second and third position error detection units is weighted with a predetermined weight and then synthesized and used to The image light from the iris region is drawn into and held in the imaging sensor unit so that the center of the iris image formed on the imaging sensor unit and the polar coordinate pole of the polar sensor coincide with each other. The iris information sensor according to claim 3.   Each of the photoelectric conversion pixels has a shape in which the width in the circumferential direction varies depending on the position in the radial direction because of weighting in the radial direction in the photoelectric conversion pixels, and the width in the circumferential direction is different from each photoelectric conversion pixel. 5. The iris information sensor according to claim 1, wherein the iris information sensor is larger than both ends of the radial position at a central portion of the radial position.   The iris information sensor according to claim 5, wherein the plurality of photoelectric conversion elements of the second position error detection unit have a shape complementary to a shape of a gap between the photoelectric conversion pixels.

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