JP2005244549A - Imaging apparatus for authentication - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To image a focused image for authentication even if a person to be authenticated is moving. <P>SOLUTION: An imaging apparatus for authentication comprises a lens 2 for condensing incident light from the person 1 to be authenticated; a light split prism 3 for splitting the incident light condensed by the lens 2 into a plurality of portions; and a plurality of imaging means 4a, 4b, 4b, where optical path lengths Da, Db, Dc from the center point of the lens 2 are arranged at different positions, and the incident light split by the light split prism 3 is imaged each, thus expanding the depth of field by three times larger than the case of one imaging means, and easily acquiring the focused image for authentication even if the person 1 to be authenticated is moving. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an authentication image capturing apparatus used in a security system, and more particularly to an authentication image capturing apparatus that can capture a focused authentication image even when a person to be authenticated is moving.

  With the widespread use of security systems, various types of personal authentication devices have been installed at various locations. Among these personal authentication devices, there are devices that capture an authentication image using a camera, that is, an imaging device. For example, in an iris authentication device, an iris image of a person to be authenticated is captured with a camera. Further, in an apparatus that performs authentication using a retina pattern, a retina image is captured by a camera through the pupil of the person to be authenticated.

  In addition, a personal authentication device that takes a photograph of a traveler's face at an airport, etc., extracts correlated feature quantities such as eye positions and nose positions, and compares and compares them with the feature quantities of registered people who need attention. There is also a security system used.

  In the personal authentication device using these cameras, the authenticated person may be stationary for shooting, but in order to shorten the waiting time of the authenticated person, the subject is in focus even when the authenticated person is moving. It is necessary to be able to capture a captured image. In addition, even if the person to be authenticated is imaged with no motion, the person to be authenticated will not be in a completely stationary state, so it is necessary to be able to capture an in-focus image even if it moves a little. is there.

  However, even if the automatic focus (AF) function mounted on the camera is used, it is difficult to always keep the focused person in focus. This is because it takes time to search for an in-focus position with the AF function.

  Therefore, conventionally, as described in Patent Document 1 below, in addition to a camera that captures an image for authentication, two cameras that detect the position of the person to be authenticated by a three-point method are separately provided. The range to be searched by the AF function is narrowed around the position of the person to be authenticated detected by the detection camera, and the focus position can be obtained in a short time.

JP 2000-5149 A

  However, in the above-described prior art, if the position of the person to be authenticated is not detected using a camera for position detection other than the camera for image pickup for authentication, the authentication image focused on the person to be authenticated is moving. There was a problem that it was not possible to image.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an authentication image pickup apparatus that can pick up an in-focus authentication image even if the user is moving without using a camera for detecting the person to be authenticated. It is in.

  An authentication imaging apparatus according to the present invention includes a lens that collects incident light from a person to be authenticated, a light splitting prism that divides incident light collected by the lens into a plurality, and a center point of the lens. And a plurality of image pickup means for picking up each of the incident lights divided by the light dividing prism and arranged at different positions of the optical path length.

  With this configuration, the depth of field spreads as many as the number of imaging means, and a focused authentication image can be captured even when the authenticator is moving or moving.

  The authentication image capturing apparatus according to the present invention further includes a filter unit that detects a high-frequency component amount included in each captured image captured by the plurality of image capturing units, and a plurality of images captured by each of the image capturing units. Control means for selecting, as an authentication image, a captured image that maximizes the amount of the high-frequency component in the image.

  With this configuration, it is possible to quickly select the most focused image suitable for authentication from among the authentication images captured by the plurality of imaging units.

  The authentication image capturing apparatus according to the present invention further includes lens driving means for driving the lens to adjust the focus position of the lens, and the control means applies to each captured image captured by each of the image capturing means. The lens driving unit is controlled in accordance with the magnitude comparison result of the amount of high-frequency component contained to control the moving speed of the focus position adjustment.

  With this configuration, since the focus position of the lens is adjusted according to the movement speed of the person to be authenticated, it is easy to capture a focused authentication image even while the person to be authenticated is moving.

  In the authentication image pickup apparatus of the present invention, the two image pickup means arranged in the front and back in order of the optical path length further include a depth of field when the image of the person to be authenticated is picked up by one image pickup means. The other imaging means is arranged so as to be continuous with the depth of field when imaging the person to be authenticated.

  With this configuration, since the depth of field of each imaging unit is continuous, an authentication image that is in focus by any of the imaging units can be reliably obtained.

  According to the present invention, by extending the depth of field by using a plurality of imaging means, it is possible to capture an in-focus authentication image even when the authenticated person is moving or moving, and wait for the authenticated person to wait. Time can be shortened.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a configuration diagram of an optical system of an authentication image pickup apparatus according to the first embodiment of the present invention. The authentication image pickup apparatus of this embodiment is provided for picking up an iris image of the eye 1 of the person to be authenticated, and three places of the eye 1 are shown in FIG. Indicates that it is moving.

  The optical system of the authentication image pickup apparatus includes a fixed-focus lens 2 that condenses incident light from the eye 1 of the person to be authenticated, and a light division that is arranged downstream of the lens 2 and divides the condensed light into three. And a prism 3. Then, a first solid-state image sensor 4a that captures an image of the first split light divided by the light splitting prism 3, a second solid-state image sensor 4b that captures an image of the second split light, and an image of the third split light And a third solid-state image pickup device 4c for picking up images.

  The optical path length (referred to as Da) between the center point O of the lens 2 and the first solid-state image sensor 4a, and the optical path length (referred to as Db) between the center point O of the lens 2 and the second solid-state image sensor 4b. ) And the optical path length (referred to as Dc) between the center point O of the lens 2 and the third solid-state imaging device 4c so that they are different by a predetermined distance t so as not to be the same length. Image sensors 4a, 4b, 4c are arranged. That is, when the central solid-state image sensor 4b is disposed at the focus position, the solid-state image sensor 4a is disposed at the front pin position and the solid-state image sensor 4c is disposed at the rear pin position.

  FIG. 2 is a functional block diagram of the authentication image pickup apparatus according to the first embodiment of the present invention. In FIG. 2, the solid-state imaging devices 4a, 4b, and 4c are equivalently arranged on the optical axis of the lens 2 with respect to the solid-state imaging device 4a.

  The authentication image capturing apparatus captures a captured image of the first solid-state image sensor 4a (hereinafter, a captured image captured by the first solid-state image sensor 4a is referred to as a captured image A), and a predetermined frequency range included in the captured image A. A band-pass filter (BPF) 5a for detecting a high-frequency component amount of the first image and a captured image of the second solid-state imaging device 4b (hereinafter, a captured image captured by the second solid-state imaging device 4b is referred to as a captured image B). A band-pass filter (BPF) 5b that detects a high-frequency component amount in a predetermined frequency range included in the image B and a captured image of the third solid-state image sensor 4c (hereinafter, a captured image captured by the third solid-state image sensor 4c is captured). And a band pass filter (BPF) 5c that detects a high frequency component amount in a predetermined frequency range included in the captured image C.

  The authentication image pickup apparatus of the present embodiment further includes an arithmetic control unit 6 that takes in the detection outputs of the bandpass filters 5a, 5b, and 5c and outputs a selection control signal to be described later. Although not shown, the authentication image capturing apparatus has a function of extracting an iris image from the eye image of the person to be authenticated and a function of performing processing until the feature amount is coded from the iris image. The encoded feature value is passed to the authentication device at the subsequent stage.

  If the configuration of the present embodiment is optically described, the range in which the image A captured by the solid-state image sensor 4a is in focus, that is, the depth of field, and the image B captured by the solid-state image sensor 4b are in focus. The position of the solid-state imaging device 4b with respect to the solid-state imaging device 4a is set so that the depth of field is continuous, and similarly, the depth of field in which the image B captured by the solid-state imaging device 4b is in focus The position of the solid-state imaging device 4c with respect to the solid-state imaging device 4b is set so that the depth of field where the image C captured by the solid-state imaging device 4c is in focus is continuous.

  As a result, the entire depth of field of the present embodiment is three times as large as that of an imaging device using one solid-state imaging device, and even if the authenticated person is moving, the authenticated person's focus is increased. Can be captured by any of the three solid-state imaging devices 4a, 4b, and 4c. Therefore, for example, in order to arrange both solid-state image sensors 4a and 4b so that the depth of field of the solid-state image sensor 4a and the depth of field of the solid-state image sensor 4b are continuous, the person to be authenticated is placed on one solid-state image sensor. When the first eye is focused, the amount of the high-frequency component contained in the image captured by the other solid-state image sensor is not less than a predetermined amount.

  FIG. 3 is a flowchart of the selection processing procedure executed by the arithmetic control unit 6 of FIG. As described above, the arithmetic control unit 6 selects the most focused image among the captured images A, B, and C of the three solid-state imaging devices 4a, 4b, and 4c as follows, and selects the selection control signal. Is output.

  First, the output of the bandpass filter 5a and the output of the bandpass filter 5b are compared (step S1). If the output of the bandpass filter 5a is large, the output of the bandpass filter 5a and the output of the bandpass filter 5c are next. Are compared (step S2). As a result, when the output of the bandpass filter 5a is large, that is, when the amount of high frequency components included in the image A is larger than the amount of high frequency components included in the images B and C, the image A is A selection control signal to be selected is output (step S3), and the authentication device at the subsequent stage is caused to perform authentication processing with the image A.

  As a result of comparing the output of the bandpass filter 5a and the output of the bandpass filter 5b (step S1), if the output of the bandpass filter 5b is large, the output of the bandpass filter 5b and the output of the bandpass filter 5c are next. The outputs are compared (step S4). As a result, when the output of the bandpass filter 5b is large, a selection control signal for selecting the image B is output (step S5), and the authentication apparatus at the subsequent stage is made to perform authentication processing with the image B.

  If the output of the bandpass filter 5c is large as a result of the comparison in step S2, or if the output of the bandpass filter 5c is large as a result of the comparison in step S4, the selection for selecting the image C A control signal is output (step S6), and the authentication device at the subsequent stage is caused to perform authentication processing with the image C.

  As described above, in the present embodiment, among the captured images A, B, and C of the three solid-state imaging devices 4a, 4b, and 4c, an image having the largest amount of high-frequency component, that is, an image that is in focus most. Are selected as images for authentication processing. In addition, since the high-frequency component amount is detected in hardware by the band-pass filters 5a, 5b, and 5c, high-speed processing is possible. In addition, by using the optical system of the authentication image pickup apparatus of the present embodiment, the authentication target image can be obtained even when the authentication target enters the wide depth of field and the authentication target is moving. Imaging can be performed.

(Second Embodiment)
FIG. 4 is a functional configuration diagram of the authentication image pickup apparatus according to the second embodiment of the present invention. 4 also shows the solid-state imaging devices 4a, 4b, and 4c arranged on the optical axis of the lens 2 with respect to the solid-state imaging device 4a, as in FIG.

  In the authentication image pickup apparatus of the present embodiment, a lens whose focus position is adjustable is used as the lens 8, and the moving speed of the focus position adjustment is controlled by the stepping motor 9 that receives the control command from the arithmetic control unit 6. Unlike the first embodiment, other configurations are the same as those of the first embodiment.

  FIG. 5 is a flowchart showing a processing procedure executed by the arithmetic control unit 6 of the present embodiment. First, it waits for the person to be authenticated to approach (step S11). When the person to be authenticated approaches, each solid-state imaging device 4a, 4b, 4b that captures an image of the eye 1 of the person to be authenticated The outputs of the three band pass filters (BPF) 5a, 5b, 5c connected to each other are compared (step S12).

  If BPF5a> BPF5b> BPF5c is established as a result of this comparison, that is, if the relationship of FIG. 6A is established, the moving speed of the focus position adjustment of the lens 8 is decreased (step Next, it is determined whether or not the person to be authenticated has entered the shooting distance (step S14). When the shooting distance is entered, the process proceeds to the image selection process (step S15) described with reference to FIG.

  If it is not within the photographing distance, the process returns to step S12 described above, and the output comparison of each of the bandpass filters 5a, 5b, and 5c is performed again. If the relationship of FIG. 6A is not established as a result of the comparison of the bandpass filters 5a, 5b, and 5c, next, whether or not the relationship of FIG. It is determined whether> BPF 5c is established (step S16).

  As a result of this determination, when the relationship of FIG. 6B is established, the moving speed of the focus position adjustment of the lens 8 is maintained as it is (step S17), and the process proceeds to the above-described step S14 to cover the shooting distance. It is determined whether or not an authenticator has been entered.

  As a result of comparing the outputs of the three bandpass filters 5a, 5b, and 5c (step S16), if the relationship of FIG. 6B is not established and the relationship of FIG. The moving speed of the focus position adjustment is increased (step S18), and the process proceeds to the above steps 14 and 14 to determine whether or not the person to be authenticated has entered the shooting distance.

  With the above processing, in the present embodiment, the moving speed of the focus lens constituting the lens 8 is controlled so as to match the moving speed of the person to be authenticated. In the same manner as described above, it is possible to keep focusing on the middle solid-state imaging device 4b, for example, while capturing within a wide depth of field. In particular, in this embodiment, it is easy to capture a focused authentication image without stopping the person to be authenticated.

(Third embodiment)
FIG. 7 is a configuration diagram of an optical system of an authentication image pickup apparatus according to the third embodiment of the present invention. In the first and second embodiments, three solid-state image sensors are arranged via a light splitting prism for one lens system. However, the present invention is not limited to three, and two solid-state image sensors are arranged. It may be arranged, or may be configured to arrange four or more solid-state imaging devices.

  This third embodiment is an embodiment in which four solid-state image sensors are arranged. A light splitting prism 11 that splits the light collected by the lens 10 into four parts is arranged at the rear stage of the lens 10, and this Four solid-state imaging devices 12a, 12b, 12c, and 12d that image each divided light emitted from the light dividing prism 11 are provided.

  The optical path lengths from the lens center point O of each solid-state imaging device 12a, 12b, 12c, 12d are the same as those in the first and second embodiments, respectively, so as to be separated by a required distance. Other configurations such as a configuration for selecting an image for authentication based on the amount of high-frequency components included in the captured images of the solid-state imaging devices 12a, 12b, 12c, and 12d are the same as those in the first and second embodiments.

  As described above, according to each of the above-described embodiments, the depth of field can be expanded by using only one lens system, and the authentication image that is in focus even when the authentication target is moving. Can be imaged.

  The authentication image pickup apparatus according to the present invention can reduce the waiting time of the person to be authenticated because the range in which the image for authentication in focus can be picked up even if the person to be authenticated moves, and can be authenticated while moving Therefore, the present invention is useful when applied to a personal authentication device using an imaging device such as an iris authentication device.

1 is a configuration diagram of an optical system of an authentication image pickup apparatus according to a first embodiment of the present invention. 1 is a functional block diagram of an authentication image capturing apparatus according to a first embodiment of the present invention. 6 is a flowchart showing a processing procedure of the authentication image pickup apparatus according to the first embodiment of the present invention. Functional block diagram of an authentication image pickup apparatus according to the second embodiment of the present invention It is a flowchart which shows the process sequence of the image pick-up apparatus for authentication which concerns on the 2nd Embodiment of this invention. Explanatory drawing of the processing content of the image pick-up apparatus for authentication which concerns on the 2nd Embodiment of this invention. The block diagram of the optical system of the image pick-up apparatus for authentication which concerns on the 3rd Embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Person's eyes 2, 8, 10 Lens 3, 11 Light splitting prism 4a, 4b, 4c, 12a, 12b, 12c, 12d Solid-state image sensor 5a, 5b, 5c Bandpass filter 6 Calculation control part 9 Stepping motor

Claims (4)

  A lens that collects the incident light from the person to be authenticated, a light splitting prism that divides the incident light collected by the lens into a plurality, and a position where the length of the optical path length from the center point of the lens is different And a plurality of image pickup means for picking up each of the incident light beams divided by the light splitting prism.   Filter means for detecting a high-frequency component amount included in each of the picked-up images picked up by the plurality of pick-up means, and picking up the high-frequency component amount among a plurality of picked-up images picked up by each of the image pick-up means The authentication image capturing apparatus according to claim 1, further comprising a control unit that selects an image as an authentication image.   A lens driving unit configured to drive the lens to adjust the focus position of the lens, and the control unit is configured according to a comparison result of magnitudes of high-frequency components included in each captured image captured by each of the imaging units. The authentication image capturing apparatus according to claim 2, wherein the lens driving unit is controlled to control a moving speed of the focus position adjustment.   The two image pickup units arranged at the front and rear in the order of the optical path length pick up an image of the person to be authenticated with a depth of field when the image pickup person is picked up by one image pickup means and the other image pickup means. 4. The authentication image pickup apparatus according to claim 1, wherein the authentication image pickup apparatus is arranged so as to be continuous with the depth of field.

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