JP2005267378A - Image detecting device and abnormality detecting method for image detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect abnormality of a sensor face where light from an object to be detected passes through. <P>SOLUTION: A telephone 120 has a control circuit 122, a communication circuit 124, a liquid crystal monitor 126, an input device 128, an alarm 129, a storage part 130 for storing each piece of data, a light emitting circuit 132 which supplies power to a fingerprint sensor 20, a light receiving circuit 134 which receives a detection signal outputted from a light sensor chip 40 of the fingerprint sensor 20 to convert the signal into image data, and fingerprint image generation part 136 which synthesizes the image signal from the light receiving circuit 134 to generate a fingerprint image for each line. The control circuit 122 reads the detection signal from a light receiving element 42, stores the waveform pattern of the detection signal in the storage part 130, compares the stored waveform pattern of the detection signal with a reference pattern of the detection signal, and on the basis of a difference between the waveform pattern of the detection signal and the reference pattern of the detection signal, determines whether or not the sensor face 61 of the fingerprint sensor 20 is normal. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image detection device, and more particularly to an image detection device configured to optically detect an image of a detection object in contact with a sensor surface and an abnormality detection method for the image detection device.

  In recent years, from the viewpoint of security, a fingerprint sensor that detects an operator's fingerprint (object to be detected) for personal authentication in an electronic device such as a computer or a mobile communication device such as a mobile phone and identifies whether or not the person is the person Preparation is being studied. For example, there are two types of fingerprint sensors: one that detects the image of a fingerprint by detecting the scattered light within the fingertip that is scattered inside the fingertip that has been irradiated with light, and the light receiving element in a row. There is a method of detecting a fingerprint image by sliding a fingertip on the sensor surface of the line type photosensors arranged side by side.

  As a conventional optical fingerprint sensor, as shown in FIG. 11A, a method using light reflected from the surface of the finger, and as shown in FIG. Then, it is roughly divided into a method using scattered light emitted from the finger surface. 11A and 11B, 1 is a fingertip, 2 is a glass plate, 3 is a light emitting diode serving as an irradiation light source, 4 is an optical sensor, and 10 is projection light. 11 is reflected light reflected from the surface of the finger, 12 is light scattered within the finger, and 13 is light scattered within the finger emitted from the surface of the finger.

  As shown in FIG. 11A, the method of using light reflected by the fingertip 1 has a large variation in the fingerprint image to be acquired depending on whether the fingertip 1 is in a wet state or a dry state, and fingerprint authentication is possible. In order to obtain an image of a certain quality, complicated image processing is required, a special processor is required, and it is difficult to keep the manufacturing cost low.

  As shown in FIG. 11B, the method using scattered light within the finger can acquire a high-quality fingerprint image that is hardly affected by the fingertip 1 in a wet or dry state. Therefore, image processing is simple, a normal processor is sufficient, and manufacturing costs can be kept low. The refractive index of the finger is approximately 1.5 to 1.7.

In addition, in the method using the scattered light within the finger, the scattered light within the finger that is scattered inside the fingertip and emitted from the surface of the fingertip is detected using an optical fiber inclined at a predetermined angle with respect to the sensor surface. (For example, refer to Patent Document 1).
JP-A-6-300930

  However, in the image detection apparatus using the optical fingerprint sensor that optically detects the fingerprint by bringing the fingertip into contact with the sensor surface as described above, the sensor surface is damaged, or water droplets are present on the sensor surface. If it adheres, the fingerprint cannot be detected accurately, resulting in a problem that the fingerprint detection accuracy is lowered.

  In particular, when detecting an image of the fingertip through an optical fiber in which the scattered light within the finger that is scattered inside the fingertip and exits from the surface of the fingertip as described above is inclined at a predetermined angle with respect to the sensor surface, If an element that changes the incident angle of light such as a scratch or a water droplet is formed, there is a risk that the light to be detected may not be received, and conversely the light is not detected when fingerprint detection is not performed. There is a possibility that the received light may be received, and this also causes a problem that the fingerprint detection accuracy is lowered.

  Therefore, an object of the present invention is to provide an image detection apparatus and an abnormality detection method for the image detection apparatus that solve the above-described problems.

The invention according to claim 1 is a transparent member having a sensor surface that comes into contact with the detection object, a light irradiation unit that irradiates the detection object with detection light, and light from the detection object via the transparent member. In a light receiving element that receives light and an image detection device that detects an image by detection light received by the light receiving element,
An abnormality detection unit is provided that reads a detection signal from the light receiving element and detects the presence or absence of an abnormality in the sensor surface based on a change in output of the detection signal.

  The abnormality detection means according to claim 2 is a storage means for storing a reference value of a detection signal from a light receiving element when the detected object does not contact the sensor surface, and the storage means stores the reference value. A detection means is provided for comparing the reference value of the detection signal with the detection signal to determine whether the sensor surface is abnormal.

  According to a third aspect of the present invention, the abnormality detecting means detects the presence or absence of an abnormality of the sensor surface when in an undetected state in which an image of the detected object is not detected.

  According to a fourth aspect of the present invention, there is provided an informing means for informing an abnormality when the abnormality detecting means determines that there is an abnormality in the sensor surface.

  The transparent member according to a fifth aspect of the invention is configured such that a plurality of optical fibers are held in a state where the optical fibers are inclined at a predetermined angle with respect to the sensor surface, and is incident when the detected object comes into contact with the sensor surface. The light is guided to the light receiving element.

  According to a sixth aspect of the present invention, there is provided a transparent member having a sensor surface that comes into contact with the detected object, a light irradiation unit that irradiates the detected object with detection light, and light from the detected object via the transparent member. A first step of reading a detection signal from the light receiving element, and a reference of the detection signal in the abnormality detection method of the image receiving device that detects an image by the detection light received by the light receiving element A second step of reading a value, a third step of comparing the detection value with the reference value read in the second step, and when the detection signal is greater than or equal to the reference value, And a fourth step of determining occurrence of abnormality.

  According to the present invention, a detection signal from a light receiving element that receives light from a detection object via a transparent member is read, and the presence or absence of an abnormality in the sensor surface of the transparent member is detected based on the output change of the detection signal. Therefore, it is possible to automatically detect an abnormality such as a scratch formed on the sensor surface or adhesion of water droplets, and based on this, it is possible to eliminate a decrease in detection accuracy due to an abnormal part of the sensor surface. .

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

  1 (A) to 1 (C), 2 (A), 2 (B), and 3 show an embodiment 1 of an image detection apparatus according to the present invention. 1A is a perspective view, FIG. 2A is a plan view, and FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2A. FIG. 1A is a perspective view showing the inside of the fingerprint sensor 20 so that the inside structure can be easily understood. In each figure, X1-X2 indicates the longitudinal direction, Y1-Y2 indicates the width direction, and Z1-Z2 indicates the thickness direction.

  As shown in FIGS. 1 to 3, the fingerprint sensor 20 is an image detection apparatus that uses scattered light within a finger and collects a fingerprint as a detection target by sliding the finger. On the interposer (printed wiring board) 21 of the fingerprint sensor 20, light emitting diode chips 30-1 to 30-3, an optical sensor chip 40, a capacitor chip 50, a resistance element, a transistor, and the like are mounted.

  Further, a light guide image guide member (transparent member) 60 is mounted on the optical sensor chip 40, and an illumination guide member 80 is mounted on the light emitting diode chips 30-1 to 30-3. The light emitting diodes 30-1 to 30-3, the optical sensor chip 40, the capacitor chip 50, the resistor element, the transistor, the light guide image guide member 60, and the illumination guide member 80 are covered and surrounded by the synthetic resin mold portion 90. And has an integrated mold structure. The fingerprint sensor 20 has a length L1 of about 17 mm, a width W1 of about 5 mm, and a height H1 of about 3 mm, and is small.

  1 to 3, the interposer 21 is a rectangular printed circuit board that extends in the X1-X2 direction.

  The optical sensor chip 40 has a configuration in which a large number of 256 light receiving elements 42 are formed in a line along the longitudinal direction of the substrate 41 on an elongated substrate 41 made of, for example, a silicon material. The light receiving elements 42 have a size of about 40 μm square, for example, are arranged at a pitch of 43 μm, for example, 600 dots / inch, and the number is, for example, 256. The optical sensor chip 40 is mounted on the Y1 side of the interposer 21, and the light receiving elements 42 are arranged in a line in the X1-X2 direction.

  As shown in FIG. 3, a light guide image guide member 60 is adhered on the optical sensor chip 40 with an adhesive layer 100 of an optical adhesive.

  Here, for convenience of explanation, three surfaces orthogonal to each other are defined with reference to the arrangement direction of the light receiving elements 42. In FIG. 1B, reference numeral 200 denotes an XZ plane, which is a vertical plane in the light receiving element arrangement direction, and is referred to as a “light receiving element arrangement direction vertical plane”. Reference numeral 201 denotes an XY plane, which is a horizontal plane. Reference numeral 202 denotes a YZ plane, which is a vertical plane perpendicular to the light receiving element arrangement direction, and is referred to as “light receiving element arrangement perpendicular direction vertical plane”.

  Further, a terminal on the substrate 41 and a terminal on the interposer 21 are connected by a wire 43 by wire bonding.

  The three light emitting diode chips 30-1 to 30-3 are mounted on the Y2 side of the interposer 21, and are arranged in the X1-X2 direction. The light receiving element 42 and the light emitting diode chips 30-1 to 30-3 are adjacent to each other in the Y1-Y2 direction and are arranged in the X1-X2 direction. The light emitting diode chips 30-1 to 30-3 emit infrared light having a wavelength of, for example, 900 to 1000 nm. The light emitted from the light emitting diode chips 30-1 to 30-3 may be red light having a wavelength of 600 nm or more. Further, instead of the light emitting diode chips 30-1 to 30-3, light emitting diodes of molded parts may be used.

  The illumination guide member 80 has a role of guiding infrared light emitted from the light emitting diode chips 30-1 to 30-3 to the upper surface of the fingerprint sensor 20. The illumination guide member 80 is a resin molded part made of, for example, acrylic, polycarbonate, or methacrylic resin, and has a shape that is long in the X1-X2 direction and has legs 81 and 82 at both ends.

  The illumination guide member 80 is disposed so as to straddle the upper side of the light emitting diode chips 30-1 to 30-3, the leg portions 81 and 82 are in contact with the interposer 21, and the position of the height is determined. The adhesive layer 101 is adhered to the upper surfaces of the light emitting diode chips 30-1 to 30-3.

  The synthetic resin mold portion 90 is made of epoxy resin, is integrated with the interposer 21, covers the light emitting diodes 30-1 to 30-3, the optical sensor chip 40, the capacitor chip 50, the resistance element, and the transistor, and The light guide image guide member 60 is surrounded, and the illumination guide member 80 is surrounded. Therefore, the interposer 21, the light emitting diodes 30-1 to 30-3, the optical sensor chip 40, the capacitor chip 50, the resistor element, the transistor, the light guide image guide member 60, and the illumination guide member 80 are integrated by the synthetic resin mold portion 90. It has become.

  The sensor surface 61 formed on the upper surface of the light guide image guide member 60 and the upper surface 83 of the illumination guide member 80 are exposed on the upper surface 21 of the fingerprint sensor 20.

  A peripheral portion of the upper surface of the synthetic resin mold portion 90 has a tapered inclined surface 91. This is to make the contact with the finger to be slid gently.

  Further, a flange portion 22 is formed around the lower surface side of the fingerprint sensor 20. This is so that it can be accurately attached to the equipment. Further, the height dimension H3 (see FIG. 3) from the upper surface of the flange portion 20b to the upper surface 20a of the fingerprint sensor 20 is determined by the pressing force of a resin molding die (not shown), and is accurately determined.

  Here, the principle of a method for optically detecting a fingerprint will be described. As shown in FIG. 4, the sensor surface 61 of the light guide image guide member 60 is a detection surface for sensing by touching the fingertip, and the lower surface 62 faces the light receiving element 42 of the optical sensor chip 40. . When a protective member such as a transparent protective sheet or a transparent glass plate is formed on the sensor surface 61 of the light guide image guide member 60, the upper surface of the protective member becomes the sensor surface.

  In the fingerprint sensor 20 of the present embodiment, when the fingertip 1 is brought into contact with the sensor surface 61 of the light guide image guide member 60, the convex portion 1a is the light guide image of the surface irregularities forming the fingerprint of the finger. The guide member 60 is in close contact with the sensor surface 61, and the concave portion 1 b is not in close contact with the upper surface of the light guide image guide member 60. An air layer 15 is formed between the concave portion 1 b and the sensor surface 61 of the light guide image guide member 60.

  Therefore, the light 13b emitted from the concave portion 1b of the intra-finger scattered light 12 is absorbed without being totally reflected in the light guide image guide member 60 and does not reach the light receiving element 42 of the optical sensor chip 40, and is convex. The light 13 a emitted from the portion 1 a is totally reflected in the light guide image guide member 60 and received by the light receiving element 42 of the optical sensor chip 40.

  Therefore, in the fingerprint sensor 20, when viewed from the exit surface side of the light guide image guide member 60, only the convex portion 1a of the finger surface appears bright and the concave portion 1b appears dark, and the fingertip 1 By processing the detection signal output from the optical sensor chip 40 when the is slid in the Y2 direction, a fingerprint image of a finger is created, and fingerprint pattern recognition is performed.

  In addition, as shown in FIG. 1B, the light guide image guide member 60 is a bundle of optical fiber pieces in which a large number of optical fiber pieces 70 are densely aligned, and as a whole, the X1-X2 direction. And the length L2 is about 15 mm), the width W2 is about 1 mm, and the height H2 is about 2 mm.

  As described above, the light guide image guide member 60 is configured to incline a large number of optical fiber pieces 70 by a predetermined angle, so that it absorbs light other than the scattered light incident in the air as will be described later. Although it is scattered light, it acts to absorb the scattered light within the finger that has entered through the air layer 15 so as not to propagate to the light receiving element 42, and directly from the convex portion 1 a on the surface of the fingertip without passing through the air layer 15. A part of incident finger scattered light is guided to the light receiving element 42.

  In the light guide image guide member 60, the light incident from the surrounding air and the scattered light in the finger that is incident on the air layer 15 though it is scattered in the finger are prevented from reaching the light receiving element 42. This is because these lights become noise.

Here, the light absorption and propagation action of the optical fiber piece 70 will be described.
As shown in FIG. 1B, the multiple optical fiber pieces 70 are arranged in parallel in the direction vertical plane 200 so that the lower surface 62 faces the light receiving element 42, and are X1 or Z1 with respect to the Z axis. The angle θ1 is inclined in the X2 direction, and is closely arranged in the X1-X2 direction and the Y1-Y2 direction.

  As shown in FIG. 5 (A), each optical fiber piece 70 has a core 71 extending in a columnar shape at the center, a cylindrical clad 72 around the core 71, and The structure has a light absorption layer 73 that absorbs light on the outer periphery of the clad 72, and has an incident surface 75 on which a finger comes into contact and light enters, and an output surface 76 from which light exits.

  The refractive index n1 of the core 71 is 1.62, for example, and the refractive index n2 of the clad 72 is 1.52, for example. Further, a boundary surface 74 is formed between the core 71 and the clad 72. In addition, the incident surface 75 and the emission surface 76 have an elliptical shape having a major axis in the X1-X2 direction.

  Both the entrance surface 75 and the exit surface 76 are horizontal surfaces. The incident surfaces 75 of the optical fiber pieces 70 gather to form the sensor surface 61 of the light guide image guide member 60, and the emission surfaces 76 of the optical fiber pieces 70 gather to cover the lower surface 62 of the light guide image guide member 60. Forming.

Here, the setting of the inclination angle of the optical fiber piece 70 will be described.
The angle of the incident surface 75 of the optical fiber piece 70 with respect to the optical axis 77 of the optical fiber piece 70 (equal to the angle θ1 described above) is determined as follows. That is, first, as shown in FIG. 5B, the light that has entered the core 71 from the air through the incident surface 75 is determined not to be totally reflected by the boundary surface 74.

  That is, the light 90 refracted by the incident surface 75 from a direction perpendicular to the incident surface 75 and entering the core 71 is of course incident on the incident surface 75 from a direction substantially parallel to the incident surface 75 and refracted here. The light 91 incident on the core 71 is also refracted without being totally reflected at the boundary surface 74 and enters the cladding 72 to reach the light absorption layer 73 and be absorbed there.

  Second, since the optical refractive index n of the finger is about 1.5 to 1.7, the light exits from the inside of the fingertip 1 and does not pass through the air layer 15 as shown in FIG. It is determined that a part of the finger scattered light 95 incident on the core 71 through the surface 75 is incident on the boundary surface 74 at an angle θ6 larger than a critical angle θ2, which will be described later, and is totally reflected. is there. The light totally reflected by the boundary surface 74 reaches the emission surface 76 and is emitted from here to the light receiving element 42.

Here, when the refractive index n1 of the core 71 is 1.62 and the refractive index n2 of the clad 72 is 1.52, the angle θ1 is optically calculated. In FIG. 5A, θ2 is a critical angle at the interface between the core 71 and the clad 72.
The angle θ4 is a refraction angle of the light that has been refracted by the incident surface 75 and has entered the core 71 from the right side through the air to the incident surface 75 in FIG. 5A.
The angles θ3, θ4, θ5, and θ1 are in a relationship of θ3 = 90−θ2, θ5 = θ3 + θ4, and θ1 = 90−θ5.

The critical angle θ2 is θ2 = sin ⁻¹ (1.52 / 1.62) ≈70, and the angle θ4 is θ4 = sin ⁻¹ (1 / 1.62) ≈38. θ3 is 20 degrees, θ5 is 58 degrees, and θ1 is about 32 degrees.

  Therefore, theoretically, the angle θ1 needs to be smaller than 32 degrees. However, in this embodiment, the angle θ1 is about 40 degrees. This is because, even when the angle θ1 is greater than 32 degrees, for example, about 40 degrees, it has been confirmed by experiments that a fingerprint image of a finger with good contrast is displayed.

  The reason is considered that the boundary 74 between the core 71 and the clad 72 is in a gradation (nonuniformity) state, and irregular reflection occurs in this portion. The inventor has confirmed through experiments that the angle θ1 is not limited to 40 degrees and that there is no practical problem even when the angle θ1 is about 48 degrees. It has been found that the angle θ1 may be in the range of 38 to 48 degrees, for example.

  In addition, mounting of the light guide image guide member 60 becomes more difficult as the angle θ1 of the optical fiber piece 70 becomes an acute angle. However, the angle θ1 is about 40 degrees, and it is not difficult to mount the light guide image guide member 60. Further, the angle θ1 of the optical fiber piece 70 and the length L2 of the light guide image guide member 60 are in a relation that the length L2 becomes shorter as the angle θ1 becomes larger, and the angle θ1 is set to 40 degrees that is larger than 32 degrees. This shortens the length L2 of the light guide image guide member 60, and finally shortens the length L1 of the fingerprint sensor 20.

  Since each optical fiber piece 70 is positioned in the vertical plane 200 in the light receiving element 42 alignment direction as described above and is inclined in the X1 or X2 direction with respect to the Z axis, the light guide image guide member 60 has a width W2. Is shortened to about 1 mm, which ultimately reduces the width W1 of the fingerprint sensor 20.

  In addition, as shown in FIG. 2B, the size relationship between the optical fiber piece 70 and the light receiving element 42 is such that the emission surfaces 76 of the two optical fiber pieces 70 adjacent in the Y1-Y2 direction receive one light. This is a relationship facing the element 42.

  Next, an attachment state and a use state when the fingerprint sensor 20 is used as an authentication device for a mobile phone will be described.

  As shown in FIG. 6, the fingerprint sensor 20 is positioned at the slit 121 portion of the casing 120 of the mobile phone using the flange portion 20 b, and the upper surface 20 a is exposed on the surface of the casing 120. In the state, the seal member 130 is incorporated so as to guarantee the drip-proof property. Since the position of the fingerprint sensor 20 is determined by the flange portion 20b coming into contact with the casing 120 and the accuracy of the height dimension H3 is good, the fingerprint sensor 20 has an upper surface 20a with respect to the outer surface 122 of the casing 120 of the mobile phone. Position accuracy is high.

  When collecting a fingerprint, the fingertip 1 is pressed against the upper surface (sensor surface) 20a of the fingerprint sensor 20 and slid in the Y2 direction, as shown in FIG. As a result, the light emitting diode chips 30-1 to 30-3 emit light, and the light 10 passes through the adhesive layer 101 and the illumination guide member 80, exits from the upper surface of the illumination guide member 80, enters the fingertip 1, and the fingertip. Scattered by the tissue in 1, the fingertip 1 becomes brighter.

  As shown in an enlarged view in FIG. 4, out of the scattered light within the finger from the surface of the part of the fingertip 1 that is in contact with the sensor surface 61 of the image guide member 60, the light emitted from the concave part 1 b of the fingertip 1. The light 13 b is absorbed in the light guide image guide member 60 and is not received by the optical sensor chip 40. The light 13a emitted from the convex portion 1a of the fingertip 1 is totally reflected in the light guide image guide member 60 and reaches the light receiving element 42 of the optical sensor chip 40, and processes information from the optical sensor chip 40. The linear fingerprint information of the portion of the fingertip 1 that is in contact with the light guide image guide member 60 is obtained.

  Then, by sliding the fingertip 1, the portion of the fingertip 1 that is in contact with the sensor surface 61 of the light guide image guide member 60 moves to the fingertip side, and the linear fingerprint information obtained from time to time Together, the surface fingerprint information of the fingertip 1 is obtained.

  Since the peripheral portion of the upper surface of the fingerprint sensor 20 is a tapered inclined surface 91, there is no feeling that the fingertip is caught on the upper surface edge of the fingerprint sensor 20, and the fingertip slides smoothly.

FIG. 7 is a block diagram illustrating a configuration example of the mobile phone 120.
As shown in FIG. 7, the cellular phone 120 includes a control circuit 122, a communication circuit 124, a liquid crystal monitor 126, an input device 128 including a numeric keypad and various keys, and an alarm (notification unit) that issues a warning when an abnormality is detected. 129, a storage unit 130 for storing each data, a light emitting circuit 132 for supplying power to the light emitting diode chips 30-1 to 30-3 of the fingerprint sensor 20, and a detection signal output from the optical sensor chip 40 of the fingerprint sensor 20. Is received and converted into image data, and a fingerprint image generating unit 136 that generates a fingerprint image for each line by synthesizing image signals from the light receiving circuit 134.

  In addition, the storage unit 130 reads a detection signal from the light receiving element 42 as an abnormality detection unit, and stores a waveform pattern of the detection signal in the storage unit 130, and a waveform pattern and a detection signal of the stored detection signal. And a control program (discriminating means) for comparing the reference pattern of the detection signal and determining whether or not the sensor surface 61 of the fingerprint sensor 20 is abnormal based on the difference between the waveform pattern of the detection signal and the reference pattern of the detection signal. ing.

  Here, the control process executed by the control circuit 122 will be described with reference to the flowchart shown in FIG.

  As shown in FIG. 8, when the operation mode is selected by the input device 128 in S11, the control circuit 122 proceeds to S12 and confirms whether or not the selected operation mode is the authentication mode. In S12, when an operation mode other than the authentication mode is selected, the process proceeds to S13 and shifts to another operation mode (for example, a call mode, a mail mode, etc.).

  If the authentication mode is selected in S12, the process proceeds to S14, where a light emission command signal is output to the light emitting circuit 132 to cause the light emitting diode chips 30-1 to 30-3 of the fingerprint sensor 20 to emit light. .

  Thereby, in the fingerprint sensor 20, the light emitting diode chips 30-1 to 30-3 emit light, and this light is irradiated onto the sensor surface 61 through the illumination guide member 80. In the state where the fingertip is not in contact with the sensor surface 61, ideally, the scattered light from the fingertip from the fingertip is not received by the light receiving element 42, and no detection signal is output. However, FIG. In B), it is assumed that some light is incident on the light receiving element 42 and no detection signal (reference value A) is output in a state where the fingertip is not in contact with the sensor surface 61. The reference value A is infinitely close to zero.

  In the next S15, the mode is switched to a contact surface monitoring mode for monitoring the surface of the sensor surface 61 with which the fingertip contacts. In S16, detection in a non-contact state in which the fingertip is not in contact with the sensor surface 61 is started. Subsequently, in S <b> 17, it is confirmed whether or not the detection level of the detection signal output from the multiple light receiving elements 42 arranged in one column is greater than a preset reference value A. When the detection level of the detection signal is equal to the reference value A (almost zero), it can be determined that there is no abnormality on the sensor surface, and when a part of the detection signal becomes larger than the reference value A It can be determined that there is a high possibility that some abnormality has occurred on the sensor surface 61.

  In S17, when the detection level of each detection signal output from each light receiving element 42 is equal (almost zero) to the reference value A, the waveform pattern I is in a normal state (see FIG. 9A). Therefore, it is determined that there is no abnormality in the sensor surface 61, and the process proceeds to S18. In S18, the start of authentication by fingerprint detection is displayed on the liquid crystal monitor 126 and notified. Subsequently, the process proceeds to S19, and reading of the detection signal from each light receiving element 42 corresponding to the fingerprint touched to the sensor surface 61 is started.

  In next S20, the light emission command signal to the light emitting circuit 132 is stopped, and the voltage application to the light emitting diode chips 30-1 to 30-3 is stopped.

  In the next S21, the fingerprint image generation unit 136 generates a fingerprint image for each line obtained by synthesizing the image signals from the light receiving circuit 134. Then, it progresses to S22 and it is confirmed whether the created fingerprint image is registered. If registration of the created fingerprint image is selected by operation of the input device 128 in S22, the process proceeds to S23, and the fingerprint image data is registered in the storage unit 130 as authentication data (reference data). In S24, when the authentication process is continued, the process returns to S14 and the authentication process is continued. In S24, if the end of the authentication process is selected by operating the input device 128, the current process is terminated.

  In S17, as shown in the waveform pattern II (see FIG. 9B), there is a portion where the detection level of each detection signal output from each light receiving element 42 is larger than a preset reference value A. In some cases, for example, the mobile phone 120 is accidentally dropped, and the sensor surface 61 of the fingerprint sensor 20 is scratched, or it is determined that there is some abnormality such as water droplets attached due to rain. Proceeding to S25, the fact that an abnormality has occurred in the sensor surface 61 is displayed on the liquid crystal monitor 126 and notified.

  In S26, an alarm is generated from the alarm 129. As a result, the operator recognizes that there is some abnormality in the sensor surface 61 of the fingerprint sensor 20, and visually determines whether the sensor surface 61 is to be cleaned (for example, a wiping operation) or needs to be repaired. It becomes possible to do.

  Thereby, the control circuit 122 detects the presence or absence of abnormality of the sensor surface 61 based on the output change of each detection signal output from each light receiving element 42, thereby causing scratches or water droplets attached to the sensor surface 61, etc. It is possible to automatically detect the occurrence of the abnormality, and based on this, it is possible to eliminate the decrease in detection accuracy due to the abnormal part of the sensor surface 61.

  Further, in S27, it is confirmed whether the sensor surface 61 is cleaned and the abnormality is removed. In S27, when the sensor surface 61 is not cleaned, the process returns to S11 and the processes after S11 are repeated. In S27, when the sensor surface 61 is cleaned, the process proceeds to S28, and re-detection in a non-contact state in which the fingertip is not in contact with the sensor surface 61 is started.

  In S29, it is confirmed whether or not the detection level of the detection signal output from each light receiving element 42 is greater than a preset reference value A. In S29, when the detection level of the detection signal output from each light receiving element 42 is equal to (almost zero) the preset reference value A, water droplets and foreign matter adhering to the sensor surface 61 are removed. Determination is made and the process proceeds to S18, and the processes after S18 are executed.

  In S29, if the detection level of the detection signal output from each light receiving element 42 is larger than the preset reference value A, the sensor surface 61 is scratched and cannot be removed even after cleaning. Determine and proceed to S30.

  In S30, regarding the output of the light receiving elements 42 having the pixel numbers Pn to Pn + x, which are detected to be larger than the reference value A among the respective light receiving elements 42, store in the storage unit 130 that they are excluded from the fingerprint matching calculation target. By recognizing the pixel number as a non-detection unit, errors in subsequent authentication processing are prevented. Thereafter, the process proceeds to S18 described above, and the processes after S18 are executed.

  Then, by ignoring the detection of the pixel number recognized as a non-detection unit in S30, it is possible to prevent erroneous detection when performing authentication processing even if the sensor surface 61 is damaged.

  If the fingerprint image has already been registered as authentication data (reference data) in S22, the process proceeds to S31 to check whether or not to perform authentication. If it is determined in S31 that authentication is to be performed by operating the input device 128, the process proceeds to S32, in which the fingerprint image (registered authentication data) registered in advance is compared with the fingerprint image created in S27.

  In S33, when the collation result is a fingerprint image match, the process proceeds to S34, and the authentication OK is displayed on the liquid crystal monitor 126 and notified. In S33, if the collation result does not match the fingerprint image, the process proceeds to S35, in which the authentication NG is displayed on the liquid crystal monitor 126 and notified, and that the identity cannot be confirmed by voice. The authentication result can also be transferred to a host computer (not shown) that performs electronic payment via the communication circuit 124.

  If it is determined in S31 that authentication is not performed by operating the input device 128, the process proceeds to S36, the authentication mode is canceled, and the current process is terminated.

10A and 10B show a fingerprint sensor 20A according to the second embodiment of the present invention. In FIGS. 10A and 10B, parts common to those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.
As shown in FIGS. 10A and 10B, the fingerprint sensor 20A is an area type optical sensor chip in which a large number of optical fiber pieces 70 and light receiving elements 42 of the light guide image guide member 60 are arranged in a matrix. . Therefore, in the fingerprint sensor 20A, it is not necessary to slide the fingertip as in the first embodiment, and the light emitted from the light source 140 is applied to the fingertip 1 via the optical fiber piece 70 by pressing the fingertip against the sensor surface 61. The light irradiated and reflected by the fingertip 1 propagates through the optical fiber piece 70 and is received by the light receiving elements 42 arranged in a matrix.

  Therefore, it is not necessary to slide the fingertip as in the first embodiment, and an image of the fingertip can be detected by pressing the fingertip 1 against the sensor surface 61. By applying the control process of the flowchart shown in FIG. 8 to the apparatus that performs the authentication process using the area type optical sensor chip as described above, it is possible to monitor whether there is an abnormality on the entire surface of the sensor surface 61. Become.

  Further, as shown in FIG. 11A described above, the detection method using light reflected by the fingertip 1 and the detection method using scattered light within the finger as shown in FIG. By applying the control process of the flowchart shown in FIG. 8, it becomes possible to monitor the presence or absence of abnormality on the entire sensor surface.

  In the above embodiment, the case where the fingerprint sensor is used for a mobile phone has been described as an example. However, the present invention is not limited to this, and an apparatus other than the mobile phone, for example, an ATM machine for withdrawing cash at a bank or the like, Needless to say, the present invention can also be applied to a personal computer or other terminal devices that perform online shopping.

  In the above embodiment, a fingerprint sensor for detecting a fingerprint has been described as an example. However, the present invention is not limited to this, and other types of image detection devices may be used to monitor whether there is an abnormality in a sensor surface other than the fingerprint sensor. Of course, it is also applicable.

It is a perspective view of the fingerprint sensor which becomes Example 1 of the present invention. It is a top view of the fingerprint sensor of FIG. It is sectional drawing which follows III-III in FIG. 2 (A). It is a figure which shows the state of total reflection and refraction of the light which injected into the light guide image guide member from the fingertip in the fingerprint collection state. It is a figure which shows reflection and refraction of the light in an optical fiber piece while expanding and showing the optical fiber piece which comprises a light guide image guide member. It is a figure which shows the attachment state and fingerprint collection state to the apparatus of the fingerprint sensor of FIG. 4 is a block diagram illustrating a configuration example of a mobile phone 120. FIG. 4 is a flowchart for explaining control processing executed by a control circuit 122; It is a wave form diagram of a detection signal detected from a plurality of light receiving elements. It is a figure which shows the fingerprint sensor which becomes Example 2 of this invention. It is a figure explaining the system of a fingerprint sensor.

Explanation of symbols

20, 20A Fingerprint sensor 21 Interposer 30-1 to 30-3 Light emitting diode chip 40 Optical sensor chip 42 Light receiving element 60 Light guiding image guide member 61 Sensor surface 70 Optical fiber piece 80 Illumination guide member 90 Synthetic resin mold part 120 Mobile phone 122 Control circuit 124 Communication circuit 126 Liquid crystal monitor 128 Input device 129 Alarm 130 Storage unit 132 Light emitting circuit 134 Light receiving circuit 136 Fingerprint image generation unit

Claims (6)

A transparent member having a sensor surface in contact with the detection target, a light irradiation unit for irradiating the detection target with detection light, a light receiving element for receiving light from the detection target via the transparent member, and In an image detection device for detecting an image by detection light received by a light receiving element,
An image detection apparatus comprising: an abnormality detection unit that reads a detection signal from the light receiving element and detects whether there is an abnormality in the sensor surface based on an output change of the detection signal. The abnormality detection means includes
Storage means for storing a reference value of a detection signal from a light receiving element when the detected object does not contact the sensor surface;
A determination unit that compares the detection signal with a reference value of the detection signal stored in the storage unit to determine whether the sensor surface is abnormal;
The image detection apparatus according to claim 1, further comprising:   3. The image detection apparatus according to claim 1, wherein the abnormality detection unit detects the presence or absence of an abnormality in the sensor surface in a non-detection state in which an image of the detection target is not detected.   The image detection apparatus according to claim 1, wherein the abnormality detection unit includes a notification unit that notifies the abnormality when it is determined that there is an abnormality in the sensor surface.   The transparent member is held in a state in which a plurality of optical fibers are inclined at a predetermined angle with respect to the sensor surface, and light incident when the detected object comes into contact with the sensor surface is transmitted to the light receiving element. The image detection apparatus according to claim 1, wherein the image detection apparatus is configured to guide the image detection apparatus. A transparent member having a sensor surface in contact with the detection target, a light irradiation unit for irradiating the detection target with detection light, a light receiving element for receiving light from the detection target via the transparent member, and In the abnormality detection method of the image detection device for detecting the image by the detection light received by the light receiving element,
A first step of reading a detection signal from the light receiving element;
A second step of reading a reference value of the detection signal;
A third step of comparing the reference value read in the second step with the detection signal;
A fourth step of determining occurrence of an abnormality in the sensor surface when the detection signal is equal to or greater than the reference value;
An abnormality detection method for an image detection apparatus, comprising: