JP2004185276A - Image taking device, optical element, information device, and method for correcting image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image taking device capable of being thinned and being excellent in rigidity in its cross direction. <P>SOLUTION: The image taking device includes a prism part 102 with a fingerprint reading surface 107 to which an irregular object should abut; a fingerprint reading LED 108 which produces light rays to be incident on the prism part 102; a distributed refractivity type lens 104 by which the light rays exiting the prism part 102 are collected and formed into an image at a predetermined position; and an image pickup element 105 disposed in a predetermined position. The opposite surface 161 of the prism part 102 is formed to reflect the light rays incident from the fingerprint reading LED 108 so that the rays are vertically applied to the fingerprint reading surface 107 from the inside. The opposite surface is disposed to abut a side face 181 of a member forming the distributed refractivity type lens 104. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image capturing apparatus that captures an image of an object having irregularities such as a fingerprint.
[0002]
[Prior art]
2. Description of the Related Art In recent years, information devices such as mobile phone devices, PDAs (Personal Digital Assistants), and personal computers have been rapidly spreading. In particular, in the case of mobile telephone devices, network-compatible mobile telephone devices equipped with a Web browser, an Internet-compatible mailer, and the like are rapidly spreading due to the background of miniaturization, thinning, and multifunctionality of the devices. Important processes that require security protection, such as e-commerce such as buying and selling, and depositing and withdrawing from financial institutions, are also performed on such a network-compatible mobile phone device.
[0003]
A fingerprint authentication device, which is one of the authentication methods using biometrics, has been reduced in size and thickness in order to be mounted on an information device such as a mobile phone device with high security.
[0004]
For example, in an image photographing apparatus to be mounted on a fingerprint authentication apparatus, in order to photograph an image of a fingerprint, a surface of the prism portion, which is irregularly reflected on a surface opposite to a contact surface to which a finger is to contact, is provided. There has been proposed a configuration in which a unit is arranged side by side with a prism unit and a light beam is incident on the prism unit to reduce the thickness of the entire image photographing apparatus (for example, see Patent Document 1).
[0005]
[Patent Document 1]
JP 2000-259820 A
[0006]
[Problems to be solved by the invention]
However, in such an image photographing apparatus, the condensing section for condensing the light beam emitted from the prism section is arranged in a direction to increase the thickness with respect to the prism section, and the prism section and the condensing section are arranged. Are separated from each other.
[0007]
Therefore, at the same time the thickness of the entire image capturing apparatus is inevitably increased, and at the same time, when a strong force is applied in the thickness direction, for example, when the contact surface is strongly pressed with a finger to capture a fingerprint, There is a problem that the possibility that the image photographing apparatus itself is bent or damaged is increased.
[0008]
In the present invention, in view of the above-described problems, it is possible to reduce the thickness to about several millimeters, and even when a strong force is applied in the thickness direction, it does not bend or break and has high rigidity. It is intended to provide a device.
[0009]
[Means for Solving the Problems]
An image photographing apparatus according to an aspect of the present invention includes a prism unit having a first surface to which a first object to be photographed is brought into contact and a second surface opposite to the first surface, and a light beam incident on the prism unit. A light source unit that generates the light, a light collecting unit that collects light rays emitted from the prism unit and forms an image at a predetermined position, and an imaging unit that is disposed at a predetermined position. It is formed so as to reflect the light beam incident on the prism portion from above, and irradiates the first surface in the vertical direction from the inside, and is disposed so as to abut at least a part of the side surface of the member forming the light collecting portion. It is characterized by:
[0010]
With such a configuration, the second surface opposite to the first surface of the prism portion reflects light rays incident on the prism portion from the light source portion and irradiates the first surface in the vertical direction from the inside. Since the light source unit is formed on the side surface of the prism unit, the overall thickness of the image photographing apparatus can be reduced. Further, with such a configuration, an image of an object having unevenness such as a fingerprint or Braille can be shot with high contrast as a first shooting target.
[0011]
Furthermore, according to such a configuration, the second surface facing the first surface of the prism portion and at least a part of the side surface of the member forming the light collecting portion are in contact with each other. Even when the finger is pressed with a relatively strong force, the pressing force can be dispersed, so that the possibility that the device is bent or damaged can be reduced.
[0012]
Further, the image photographing apparatus of the present invention is configured such that a prism having a first surface to which a first photographing object is to be brought into contact and a second surface opposite to the first surface is incident on the prism. A light source unit that generates light beams, a light-collecting unit that collects light beams emitted from the prism unit and forms an image at a predetermined position, and an imaging unit that is disposed at a predetermined position. The prism is formed so as to reflect a light beam incident on the prism portion from the light source portion and irradiate the first surface in the vertical direction from the inside, and the prism is provided between the second surface and the side surface of the member forming the light collecting portion. A support member for supporting the unit and the light collecting unit is arranged.
[0013]
Even with such a configuration, the second surface facing the first surface of the prism portion reflects light rays incident on the prism portion from the light source portion, and the first surface is vertically moved from the inside. Since it is formed so as to irradiate, the light source unit can be arranged on the side surface of the prism unit, and the overall thickness of the image photographing apparatus can be reduced. Further, with such a configuration, an image of an object having unevenness such as a fingerprint or Braille can be shot with high contrast as a first shooting target.
[0014]
Further, since the supporting member is disposed between the second surface of the prism portion facing the first surface and the side surface of the member forming the light collecting portion, the finger exerts a relatively strong force on the first surface. In the case where the device is pressed, the pressing force can be dispersed, so that the possibility that the device is bent or damaged can be reduced. Further, by selecting the thickness and material of the support member, it is possible to adjust the rigidity of the image photographing apparatus.
[0015]
Further, if the supporting member is configured to be a member that prevents light from leaking from the prism portion or a member that reflects a light beam emitted from the prism portion to the prism portion, the light use efficiency of the light beam can be improved. This makes it possible to shoot a high-contrast image of a shooting target.
[0016]
Further, a reflecting surface configured so that the first surface and the optical axis center of the condensing portion are parallel to each other, and reflecting light rays from the first surface in a direction coinciding with the optical axis direction of the condensing portion is provided. With the configuration provided in the prism section, the thickness of the apparatus can be reduced, and an image capturing apparatus having a thickness of about 3 mm or less can be obtained.
[0017]
Further, a second mirror in which a half mirror surface is formed instead of the reflecting surface on the surface of the prism portion where the reflecting surface is to be formed, and the half mirror surface is arranged on the side opposite to the side on which the condensing portion is arranged on the half mirror surface By taking a configuration in which the image of the target is captured by the light beam transmitted through the half mirror surface, the image is not only placed on the first imaging target image, but also disposed on the half mirror surface on the side opposite to the side on which the condensing portion is disposed. The image of the second object to be photographed can also be photographed by one image photographing apparatus.
[0018]
Furthermore, since the exit surface of the prism unit and the incident surface of the light-collecting unit are in close contact with each other, it is possible to prevent generation of stray light and loss of light rays at the interface. Further, according to such a configuration, it is possible to further increase the rigidity of the image capturing device.
[0019]
In addition, the configuration in which the light-collecting portion is a gradient-index lens makes it possible to obtain an image with little distortion even in the peripheral portion, and to reduce the size compared to a case where an optical system is configured by combining optical lenses. it can. Further, since the depth of field can be ensured, it is possible to prevent blurring or the like of a captured image.
[0020]
In addition, since the light source section is formed of a light emitting diode, the size of the light source section can be reduced. Therefore, the mounting space can be reduced, and the entire image capturing apparatus can be reduced in size.
[0021]
Further, by providing an irradiation light source unit for irradiating the second imaging target and providing a filter on the half mirror surface that selectively transmits the wavelength of the light beam reflected from the second imaging target, It is possible to prevent stray light from passing through the half mirror surface and entering from the second imaging target side when an image of the imaging target is captured.
[0022]
Further, the filter is configured to selectively transmit light having a wavelength within a range of 50 nm or more and 150 nm or less, including a light wavelength generated by the irradiation light source unit. For example, when a monochromatic LED or the like is used for the light source unit. In addition, the adverse effects of light rays of other colors can be reduced.
[0023]
Further, by configuring the imaging unit to be a CMOS sensor, it is possible to reduce the power consumption of the entire device.
[0024]
Furthermore, the configuration in which the CMOS sensor simultaneously starts exposure of all pixels and performs exposure for the same period of time can reduce image distortion when moving the image capturing apparatus with respect to the first capturing target and the second capturing target. It becomes possible to reduce.
[0025]
Further, according to the configuration in which the light beam emitted from the irradiation light source unit is reflected on the surface of the prism unit facing the irradiation light source unit to irradiate the second imaging target, the light beam is used with high efficiency. It is possible to irradiate an object to be photographed, for example, a document represented by shading.
[0026]
Further, a terminal for connecting the imaging unit of the image capturing device and the device into which the image capturing device is to be incorporated is disposed on a surface of the image capturing device that is to be in contact with the housing of the device into which the image capturing device is to be incorporated, and When the device is incorporated in the housing, the terminals are in contact with the terminals formed on the housing, so that the terminals are electrically connected to the terminals formed on the housing. This makes it possible to reduce the number of components and adhesive components, simplify the process of mounting the image capturing device, and improve the reliability of the mounting process.
[0027]
Further, the imaging unit and a terminal configured in the image capturing device are connected by a flexible substrate, and the flexible substrate is sandwiched and fixed between the image capturing device and a housing of the device in which the image capturing device is to be incorporated. Thus, connection that can easily improve the reliability can be performed as compared with the configuration in which the electrical connection to the outside is performed using the spring contact component.
[0028]
Further, by forming the slit on the flexible substrate, it is possible to improve the weather resistance against a temperature change during use.
[0029]
Furthermore, since the sealing process is performed at a portion where the prism portion and the housing holding the prism portion are in contact with each other, it is possible to prevent dirt such as sweat, dust, and the like from entering the image capturing apparatus.
[0030]
In addition, since the material used for the sealing treatment is a waterproof adhesive material, the waterproof property can be further improved.
[0031]
Further, since the first object to be photographed is a finger and the second object to be photographed is a document, an image photographing apparatus capable of photographing both a fingerprint and a document can be provided.
[0032]
Further, by configuring the information device including the image capturing device as described above, the thin image capturing of the first image capturing target constituted by unevenness such as a fingerprint or the second image represented by shading of a document or the like is performed. An information device capable of shooting a shooting target can be realized. For example, it is possible to configure an information device with high security that can perform personal authentication by photographing a fingerprint and that can realize document reading, that is, a scanner function.
[0033]
Next, the optical element according to the present invention includes an abutting surface to which the subject contacts, an incident surface to which the light beam enters, an outgoing surface to which the light beam emerges, and a light beam incident from the incident surface in the abutting surface direction. And a second reflecting surface for reflecting light rays from the abutting surface in the direction of the emitting surface.
[0034]
With such a configuration, it is possible to provide an optical element which is thin and suitable for photographing a photographing target having irregularities.
[0035]
Further, according to the configuration in which the first reflecting surface is processed so that the cross section thereof has a saw-tooth shape to form a reflecting portion, light rays can be more effectively guided to the contact surface.
[0036]
Further, according to the configuration in which the reflection portion is coated with the reflection film made of the high reflectance member, the light reflectance at the reflection portion can be improved, and the light use efficiency can be increased.
[0037]
Further, according to the configuration in which the high-reflectance member is made of aluminum, it is possible to more easily form a reflection portion having a high reflectance.
[0038]
Further, since the reflection film is formed such that the reflectance of the reflection film increases as the distance from the incident surface increases, the contact surface can be irradiated with more uniform brightness.
[0039]
In addition, since the optical element is made of plastic, an optical element that can be manufactured by a simple method such as molding and is hard to crack can be realized.
[0040]
Further, even when the optical element is made of glass, an optical element which can be formed by a simple method such as molding and has high heat resistance and is hardly damaged can be realized.
[0041]
Further, since the angle formed between the optical path from the center of the contact surface to the center of the second reflection surface and the optical axis of the light beam emitted from the emission surface is 46 degrees or less, the thickness of the optical element is reduced. An optical element that is thin in the direction can be realized.
[0042]
Furthermore, by forming a light leakage prevention film on a surface other than the incident surface, the outgoing surface, the contact surface, the first reflecting surface, and the second reflecting surface, it is possible to increase the use efficiency of light rays.
[0043]
Further, by configuring an image capturing apparatus having the above-described optical element and an information apparatus equipped with the image capturing apparatus, an image capturing apparatus that is thin and is suitable for capturing an image capturing target having irregularities and An information device can be provided.
[0044]
Next, the image correction method of the present invention is an image correction method in an image capturing apparatus that captures an image by contacting a photographing target with a contact surface, wherein the photographing target is photographed by contacting the contact surface. It is characterized in that the image is corrected using an image photographed without bringing the photographing target into contact with the contact surface.
[0045]
According to such a method, it is possible to effectively correct an image captured by an optical system in which stray light may enter into an image having a high contrast, as in the image capturing apparatus of the present invention.
[0046]
In addition, a method of performing correction by performing a difference process between an image photographed by bringing a photographing target into contact with the contact surface and an image photographed by not contacting the photographing target with the contact surface can be performed easily. An effective image contrast correction can be performed.
[0047]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0048]
(First Embodiment)
First, as a first embodiment, a configuration of an image capturing apparatus according to the present invention will be described.
[0049]
FIG. 1A is a schematic diagram illustrating an optical path of the image photographing apparatus according to the first embodiment of the present invention, and FIG. 1B is a configuration of the image photographing apparatus according to the first embodiment of the present invention. FIG. Note that FIG. 1A shows a cross-sectional shape when it is assumed to be cut along the AA ′ plane in FIG. 1B.
[0050]
In FIG. 1, an image capturing apparatus 101 according to an embodiment of the present invention is configured such that a first object to be imaged having an unevenness, for example, a finger is brought into contact with a fingerprint reading surface 107 which is a first surface. A fingerprint image can be photographed by the image sensor 105, and an image of an object represented by shading of ink, such as a document represented by shading, which is a second photographing object, faces the document or the like. An image can be taken by the image sensor 105 via the document reading surface 113.
[0051]
The prism portion 102 is an optical element, and has a fingerprint reading surface 107 for contacting a finger. The prism portion 102 is made of a transparent plastic suitable for an optical component such as polycarbonate or an optical glass such as BK7 by a known method such as injection molding or cutting. It is formed.
[0052]
The optical block 103 has a document reading surface 113, serves as an optical path for capturing an image of an object having shading such as a document, and is formed of the same material and manufacturing method as the prism unit 102.
[0053]
The document reading LED 114 is a light emitting diode for irradiating an object having a shade such as a document or a document to be photographed in order to capture an image of the object having a shade, and may be provided independently of the prism unit 102. it can. 1A and 1B, the document reading LED 114 is arranged in the housing 106, and is shaded through a gap between the optical block 103 and the housing 106 in FIG. 1B. Irradiates an object having
[0054]
The gradient index lens 104, which is a light condensing part, condenses the light beams emitted from the prism part 102 and the optical block 103 and forms an image on the surface of the image sensor 105. The refractive index distribution lens 104 includes a lens part 183 and a mold resin part 182 that holds the lens part 183.
[0055]
The image sensor 105 is an image sensor that converts a light beam condensed and imaged by the gradient index lens 104 into an electric signal, and a known CCD or CMOS sensor can be used.
[0056]
The prism unit 102, the optical block 103, and the gradient index lens 104 are housed inside a housing 106. In order to prevent unnecessary light from entering the housing 106, it is desirable that the housing 106 be a color that absorbs light, for example, black, from the viewpoint of optical performance. Materials can also be used.
[0057]
In the image photographing apparatus 101 of the present invention, the bottom surface of the prism unit 102 in FIG. 1A, that is, the facing surface 161 which is the second surface facing the fingerprint reading surface 107, and the side surface 181 of the gradient index lens 104. (In the present embodiment, the outermost surface of the mold resin portion 182) is disposed so as to abut. Further, the prism part 102 and the gradient index lens 104 are publicly known so that the light emitting surface 162 of the light from the prism part 102 and the incident side (left side in the figure) of the gradient index lens 104 are in close contact with each other. It is glued with the material. Accordingly, since the prism unit 102 and the gradient index lens 104 are fixed to each other, even when the fingerprint reading surface 107 is pressed by a finger with a strong force in the thickness direction of the image capturing apparatus 101, for example, Compared to a configuration in which there is a space between the prism section 102 and the gradient index lens 104, a configuration that is less likely to be deformed or damaged can be realized.
[0058]
In the case where the gradient index lens 104 does not have the mold resin portion 182, that is, in the case where the lens 104 has the lens portion 183, the side surface of the lens portion 183 and the opposing surface 161 abut and are fixed to each other. A configuration may be adopted. Further, between the side surface 181 of the gradient index lens 104 and the opposing surface 161 of the prism unit 102, a well-known material such as metal or plastic that supports the gradient index lens 104 and the prism unit 102 is used. Needless to say, a configuration in which the supporting members are arranged may be employed.
[0059]
In the image photographing apparatus 101 of the present invention, the surface direction of the fingerprint reading surface 107 of the prism unit 102 (the X-axis direction in FIG. 1A) and the optical axis direction of the gradient index lens 104 are parallel. Therefore, an image photographing apparatus that is thin in the thickness direction (the Y-axis direction in FIG. 1A) can be realized.
[0060]
Further, the sealing material 115 is sealed so that no gap is formed between the prism portion 102 and the housing 106. Accordingly, it is possible to prevent dirt from being attached to the prism unit 102, the gradient index lens 104, the image sensor 105, and the like due to the grease of the finger entering the inside of the image capturing apparatus 101. Can be prevented. As the sealing material 115, for example, a known waterproof adhesive material such as a silicon-based material used for caulking can be used.
[0061]
Next, an optical path when the image capturing apparatus 101 of the present invention captures an image will be described with reference to FIG.
[0062]
First, an optical path in a state where a finger does not contact the fingerprint reading surface 107 will be described.
[0063]
On one of the surfaces constituting the prism portion 102, a black light leakage prevention film 109 having a size and an angle so as to be totally reflected in the entire region of the fingerprint reading surface 107 is provided. The light image on the surface of the light leakage prevention film 109 is totally reflected by the fingerprint reading surface 107 and reflected by the mirror surface 110 that reflects light rays by an optical path indicated by a dotted arrow in FIG. Then, the light is incident on the gradient index lens 104, and the entire screen is imaged on the image sensor 105 as a black image. In the present embodiment, a half mirror is formed on the mirror surface 110 by a known method such as vapor deposition.
[0064]
When photographing a fingerprint, the fingerprint reading LED 108 is turned on. Next, when the person to be authenticated puts a finger on the fingerprint reading surface 107 and the convex portion of the fingerprint comes into close contact with the fingerprint reading surface 107, the fingerprint reading portion arranged alongside the prism portion 102 at the closely contacted portion. The light beam that has entered the prism unit 102 from the LED 108 is reflected on the facing surface 161 in the direction of the fingerprint reading surface 107 (the direction toward the Y-axis direction in the figure). The light beam is scattered at a portion where the convex surface of the fingerprint and the fingerprint reading surface 107 are in close contact with each other, and a part of the scattered light is reflected by the mirror surface 110 and enters the gradient index lens 104. As a result, the convex surface of the fingerprint is imaged white by the image sensor 105. On the other hand, the concave portion of the fingerprint is separated from the fingerprint reading surface 107, and the light rays are totally reflected by the fingerprint reading surface 107 as described above. In addition, although the reflection part is provided in the opposing surface 161 so that a light ray may be reflected, this structure is mentioned later.
[0065]
As described above, according to the image photographing apparatus 101 of the present invention, the convex surface of the fingerprint is photographed white while the concave surface of the fingerprint is photographed black in the output from the image sensor 105. Obtainable.
[0066]
The output from the image sensor 105 can be extracted as an electric signal from the external connection terminal 112 on the flexible substrate 111 via the flexible substrate 111 attached to the image sensor 105. The configuration of the flexible substrate 111 will also be described later.
[0067]
Among the surfaces constituting the prism portion 102, the fingerprint reading surface 107, the incident surface facing the fingerprint reading LED 108 on which light rays enter the prism portion 102, and the surface excluding the mirror surface 110 are also provided with the light leakage prevention film. With this configuration, it is possible to prevent the light beam incident from the fingerprint reading LED 108 from leaking out of the prism unit 102 and to prevent unnecessary disturbance light from entering the optical system.
[0068]
If the support member provided between the side surface 181 of the gradient index lens 104 and the opposing surface 161 of the prism part 102 is a member for preventing light leakage or reflecting light, The surface 161 does not need to have a light leakage prevention film.
[0069]
At this time, the angle α between the straight line connecting the center of the fingerprint reading surface 107 and the optical axis center of the mirror surface 110 and the optical axis center from the mirror surface 110 to the gradient index lens 104 is set to 46 degrees or less. By doing so, light from the outside does not enter the prism section 102 on the surface of the fingerprint reading surface 107, and a fingerprint image can be obtained by setting the entire area as a surface on which light rays are totally reflected.
[0070]
Further, since the image capturing apparatus 101 of the present embodiment is configured to have a thickness of about 1.6 mm, it can be easily mounted on a portable information device such as a mobile phone device. Note that, by further reducing the angle α, the thickness of the image capturing apparatus 101 can be reduced, so that it is easy to mount the information capturing apparatus on a thinner information device.
[0071]
Further, in the image photographing apparatus 101 of the present invention, it is possible to photograph a fingerprint image as described above, and also to photograph an image of an object represented by shading of ink such as a document.
[0072]
Next, an operation of capturing an image of the object represented by the shading will be described.
[0073]
The document reading LED 114 irradiates an object represented by shading, for example, a document such as a document, which is arranged to face the document reading surface 113. Then, in accordance with the density of the document, the reflected light from the document passes through the optical block 103, the mirror surface 110 on which the half mirror is formed, and the prism section 102 through the optical path indicated by the solid line arrow in FIG. Then, the light enters the gradient index lens 104 and forms an image on the image sensor 105 as a gray image.
[0074]
At this time, the half mirror formed on the mirror surface 110 is set so that the sum of the reflectance of light rays and the transmittance of light rays from the outside is 90% or more, for example, the internal reflectance is 50%, and the transmittance from the outside is 50%. , It is possible to effectively use the light beam and to achieve both good image capturing of a fingerprint image and image capturing of a gray-scale image.
[0075]
In this embodiment, the optical path length of the gradient index lens 104 is adjusted such that the fingerprint reading surface 107 and the image of the surface on which the document is to be placed are both imaged using the image sensor 105 as an image forming surface. Is desirable. By changing the characteristics of the gradient index lens 104 and adjusting the optical path length, the position of the surface on which the document is to be arranged can be made to coincide with the document reading surface 113 of the It is possible to adjust it slightly away from it.
[0076]
For example, the optical block 103 can be prevented from being damaged by setting the position of the surface on which the document is to be arranged slightly away from the document reading surface 113.
[0077]
Here, the configuration of the prism unit 102 used in the image photographing apparatus 101 will be described in more detail.
[0078]
First, FIG. 2A is a partial cross-sectional view illustrating the structure of the prism unit 102 viewed from the document reading surface 113 side and the reflection of light rays on the fingerprint reading surface 107 and the opposing surface 161.
[0079]
In FIG. 2A, a prism unit 102 transmits light from a fingerprint reading LED 108 to a transparent member 201 having a fingerprint reading surface 107 to which a finger 202 can be brought into close contact with the fingerprint reading surface 107 (Y-axis direction). It comprises a light source reflecting surface 205 for fingerprint, which is a reflecting portion provided on the facing surface 161 of the fingerprint reading surface 107 for guiding light. Although two fingerprint reading LEDs 108 are arranged in the Z-axis direction in the figure so as to sandwich the prism unit 102, the present invention does not limit the number of fingerprint reading LEDs 108.
[0080]
A plurality of sawtooth-shaped fingerprint light source reflecting surfaces 205 having a plurality of sawtooth cross sections are formed on the facing surface 161, and a fingerprint light source including a plurality of sawtooth surfaces whose irradiation direction (Z-axis direction) of the fingerprint reading LED 108 is a plurality of sawtooth surfaces is provided. The reflection surface 205 is disposed so as to be orthogonal to the ridge direction (X-axis direction).
[0081]
In order to suppress the attenuation of the light beam irradiating the fingerprint reading surface 107, a high reflectance member such as aluminum is deposited on the fingerprint light source reflection surface 205 so as to improve the reflectance.
[0082]
Further, in order to irradiate a light beam of uniform brightness to the entire surface of the fingerprint reading surface 107, the density of aluminum deposited on the portion of the fingerprint light source reflecting surface 205 close to the fingerprint reading LED 108 is reduced, and the fingerprint reading LED 108 It is desirable that the central portion of the fingerprint light source reflecting surface 205, which is a portion farther from the center, is configured to relatively increase the density when aluminum is deposited. Note that a configuration in which a reflection member is disposed between the prism portion 102 and the facing surface 161 without depositing a high reflectance member may be employed.
[0083]
FIG. 2B shows the light intensity distribution on the fingerprint reading surface 107 when aluminum is vapor-deposited on the fingerprint light source reflecting surface 205. The reduction in light intensity at the center position in the Z-axis direction is improved. Shows an example in which a decrease in light intensity is suppressed to an attenuation within 30% of a maximum value.
[0084]
Next, a filter formed on the prism section 102 of the image photographing apparatus 101 of the present invention will be described. This filter is formed on a mirror surface 110 between the prism unit 102 and the optical block 103 in FIG. 1, and is formed separately from a half mirror similarly formed on the mirror surface 110. Is also different.
[0085]
FIG. 3A shows an example of the wavelength distribution of the document reading LED 114 that emits light to capture an image of the document. Here, the emission peak wavelength of the document reading LED 114 is λ, and the width of the wavelength when the light intensity becomes 0 is Δλ.
[0086]
FIG. 3 (b) shows the transmission of light with respect to the wavelength of the filter (transmittance of outgoing light with respect to incident light). The width of the wavelength is Δλ ′. Here, if λ ′ = λ and Δλ ′ <Δλ, only of the light reflected from the original, the light mainly composed of the reflected light of the original reading LED 114 reaches the gradient index lens 104. Disappears.
[0087]
With such a configuration, for example, at the time of capturing a fingerprint image, unnecessary disturbance light that enters the gradient index lens 104 from the optical block 103 through the prism unit 102 can be reduced. The phenomenon that the level floats can be reduced.
[0088]
In particular, by configuring the wavelength width Δλ ′ when the transmissivity (transmittance) becomes 0 to be equal to or less than 50 nm to 150 nm, the document reading LED 114 is set to any one of the three primary colors (for example, peak When an LED having a wavelength of 630 nm is used), only light having a wavelength centered on any one color can be transmitted, so that the influence of disturbance light can be further reduced.
[0089]
In the present embodiment, the configuration where λ ′ = λ, Δλ ′ <Δλ is described. However, only the light having the wavelength of the reflected light of the document reading LED 114 as a main component reaches the gradient index lens 104. The present invention is not limited to this as long as the filter characteristic is determined so as to eliminate the problem, and the present invention can be implemented even when λ ′ ≒ λ, Δλ ′ ≦ Δλ.
[0090]
Next, the configuration of the image sensor 105 according to the first embodiment of the present invention will be described in more detail. FIG. 4 is a diagram illustrating a configuration of the image sensor 105 according to the first embodiment of the present invention.
[0091]
FIG. 4A is a diagram illustrating an example of a configuration of the imaging element 105 according to the present embodiment. As illustrated in FIG. 4A, the imaging element 105 includes photodiodes 251 arranged in a matrix. It is a CMOS sensor. Here, any two of the photodiodes 251 are referred to as a pixel A and a pixel B, respectively. The exposure periods of the pixels A and B will be described with reference to FIG. As shown in FIG. 4B, the pixel A and the pixel B of the image sensor 105 are configured to start exposure simultaneously and perform exposure for the same period. Note that reading of image information from each pixel is performed sequentially after exposure.
[0092]
With such a configuration, low power consumption is achieved by using a CMOS sensor as the image sensor 105, and by using a sensor in which exposure of each pixel is performed at the same time, the image photographing apparatus 101 can be relatively fingerprint or shaded. When taking an image while sliding the original, the image distortion can be reduced, as shown in FIG. 4C. FIG. 4C is an example of an image captured by the image capturing apparatus 101 according to the first embodiment of the present invention. The image shown in FIG. 4C is obtained by combining a plurality of partial images 252 as one image. As described above, by using the image photographing apparatus 101 of the present invention, it is possible to photograph a fingerprint or an image of a document faithfully without distortion. Therefore, it is possible to contribute to the improvement of the personal authentication rate and the character authentication rate performed after the image is captured, and the improvement of the performance of the OCR (Optical Character Recognition) operation.
[0093]
Next, the configuration of the flexible substrate 111 in the image capturing apparatus 101 will be described. FIG. 5A is a side view of the image capturing apparatus 101 according to the first embodiment of the present invention, in which a portion of the flexible substrate 111 is extracted and illustrated, and FIG. It is a schematic perspective view which shows a structure.
[0094]
In FIG. 5A, an image sensor mounting terminal 401 for extracting an electric signal from the image sensor 105 and an external connection terminal 112 for sending an electric signal from the flexible substrate 111 to the outside are provided on the flexible substrate 111. It is composed of
[0095]
As shown in FIG. 5B, in the image photographing apparatus 101 of the present invention, a slit is formed between the terminals of the image sensor mounting terminals 401 on the flexible substrate 111.
[0096]
FIG. 5C is a schematic plan view illustrating stress generation when the imaging element 105 is mounted on the flexible substrate 111.
[0097]
As shown in FIG. 5C, the degree of thermal expansion of the flexible substrate 111 and that of the image sensor 105 are different under bad conditions such as high temperature. Stress B is generated respectively.
[0098]
At this time, since the slit is formed in the flexible substrate 111, the stress generated between the imaging element 105 and the flexible substrate 111 can be divided into four stresses, stress 1 to stress 4.
[0099]
As described above, according to the configuration of the present embodiment, it is possible to reduce the possibility of peeling or disconnection of the contact portion of the flexible substrate 111 with the image sensor 105 as compared with the case where no slit is provided. It becomes.
[0100]
Note that, in the image capturing apparatus 101 of the present invention, the wiring from the imaging element 105 to the external connection terminal 112 is not limited to the flexible substrate 111, and a wiring pattern is directly formed on the housing 106 by vapor deposition or the like. Is also good.
[0101]
At this time, the external connection terminal 112 is disposed below the image capturing apparatus 101 in FIG. 1A of the housing 106, and the image capturing apparatus 101 is mounted on an external housing of an information device or the like to be mounted. If the configuration is such that the external connection terminal 112 is sandwiched between the housing 106 and the external housing of the information device, the terminal can be closely attached by providing the terminal on the external housing side. To make it conductive.
[0102]
(Second embodiment)
Next, as a second embodiment of the present invention, another configuration of the prism unit of the image capturing device will be described.
[0103]
FIG. 6A is a schematic sectional view of an image photographing apparatus 601 using the prism section 602 of the present embodiment, and FIG. 6B is a schematic plan view showing the structure of the prism section 602.
[0104]
In FIG. 6A, the same components as those described in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. FIG. 6A is a schematic cross-sectional view assuming that it is cut along the plane BB ′ in FIG. 6B.
[0105]
As shown in FIG. 6B, the prism unit 602 in the image capturing apparatus 601 according to the present embodiment reflects light emitted from the document reading LED 114 on its surface and irradiates the document. Features.
[0106]
In this manner, a plurality of document reading LEDs 114 for irradiating a document are arranged (arranged so that the center of the optical axis is oriented in the Z-axis direction in the figure) so as to be sandwiched from both sides of the image capturing apparatus 601. By using a surface of the unit 602 facing the document reading LED 114 as the document light source reflecting surface 150 to irradiate the document, it is possible to irradiate a stronger light beam to the document with a simple configuration.
[0107]
It is preferable that a high reflectance member such as aluminum is deposited on the light source reflection surface 150 for the document so as to improve the reflectance. With such a configuration, since the light beam of the document reading LED 114 does not enter the inside of the prism portion 602, the light beam inside the prism portion 602 is not adversely affected by the external light beam.
[0108]
Further, in order to irradiate a light beam of uniform brightness to the entire surface of the original to be photographed, the original light source reflecting surface 150 is painted in black beforehand, and the original reading LED 114 of the original light source reflecting surface 150 is The density of the aluminum to be evaporated is reduced in the vicinity, and the density of the aluminum when the aluminum is evaporated is relatively increased in the central portion of the light source reflecting surface 150 for the document, which is farther from the document reading LED 114. Desirably.
[0109]
In this manner, the light intensity unevenness on the document reading surface 113 can be suppressed to an attenuation within 30% of the maximum luminance.
[0110]
The means for forming the light source reflecting surface 150 for the document is not limited to the deposition of the high-reflectance member, but may be any structure that reflects light rays. For example, the original light source reflecting surface 150 may be processed into a saw-tooth surface in order to more uniformly irradiate the original reading surface 113 with the rays of the original reading LED 114 as in the case of the facing surface 161.
[0111]
In the present invention, the high reflectance member to be deposited is not limited to aluminum, but may be arbitrarily selected as long as it reflects light rays more strongly.
[0112]
In the embodiment of the present invention, an example in which a fingerprint image and a document image are photographed by one image photographing apparatus has been described. However, the present invention is not limited to this, and only a fingerprint image is photographed. It goes without saying that the present invention can be implemented as an image photographing apparatus.
[0113]
Further, by using the image photographing apparatus 101 of the present invention, since the above-described thinning is possible, mounting on a portable information device or the like becomes easy. FIG. 7 shows an example in which such an image capturing device 101 is mounted on an information device such as a mobile phone device.
[0114]
FIGS. 7A and 7B are external views of a mobile phone device 50 equipped with the image capturing device 101, wherein FIG. 7A is a front view thereof, and FIG. 7B shows an end portion of the mobile phone device 50 equipped with the image capturing device 101. It is a principal part perspective view.
[0115]
The mobile phone device 50 has a configuration in which the image capturing device 101 is built in a known mobile phone device having an antenna unit 51, a speaker unit 52, a display unit 53 such as an LCD, a key unit 54, a microphone unit 55, and the like.
[0116]
By mounting the image photographing apparatus 101 of the present invention, a document reading surface 113 for reading information expressed by shading such as characters and figures is provided on the lower surface of the mobile phone 50. It is possible to provide a mobile phone device 50 with a built-in image photographing device 101 that is easy for the user to use. In addition, by arranging the fingerprint reading surface 107 on which the fingerprint or the like is to be abutted on the surface of the mobile phone device 50 on which the key portion 54 or the like is provided, the user can easily touch the finger with the image capturing device 101. The mobile phone device 50 can be provided.
[0117]
The cellular phone 50 equipped with such an image photographing apparatus 101 reads document information such as a URL and a two-dimensional bar code, and performs processing such as OCR, or photographs a user's fingerprint pattern to perform user authentication. Therefore, it is possible to provide an information device such as a mobile phone device or the like, which has a multi-function and high security, which has not existed in the past.
[0118]
Here, the information device is not limited to the above-mentioned portable telephone device, and it goes without saying that various known information devices such as a notebook-type small personal computer and a PDA are included.
[0119]
(Third embodiment)
Next, as a third embodiment of the present invention, a method of correcting an image acquired by an image capturing device will be described.
[0120]
FIG. 8A is a partial cross-sectional view showing a structure of a part of the prism unit 102 according to the first embodiment of the present invention, which irradiates the fingerprint reading surface 107 with light. The description of each component is the same as that of the first embodiment, and will not be repeated.
[0121]
FIG. 8B shows the output level from the image sensor 105 with respect to the distance from the end face of the prism unit 102 when the finger 202 is brought into contact with the fingerprint reading surface 107. At both ends of the prism section 102, the irradiation light from the fingerprint reading LED 108 is strong, and the fingerprint reading LED 108 cannot illuminate only the fingerprint light source reflection surface 205, so that light may leak into the image sensor 105, As shown in FIG. 8B, the black level rises.
[0122]
FIG. 8C shows the output level of the image sensor 105 when the finger 202 is not brought into contact with the fingerprint reading surface 107, and the black level is raised.
[0123]
Therefore, in the present embodiment, the output value of the image sensor 105 when not touching is subtracted from the output value of the image sensor 105 obtained when the finger is in contact with the fingerprint reading surface 107.
[0124]
As a result, for example, as shown in FIG. 8D, the floating of black can be corrected, and an image with high contrast required for authentication can be obtained.
[0125]
Further, this image correction method can be specifically implemented as a control program executed by a calculation unit (not shown) that controls the operation of the image photographing apparatus of the present invention.
[0126]
FIG. 9 shows a flowchart of the processing steps of the image correction method of the present invention.
[0127]
First, the fingerprint reading LED 108 is turned on (step S901). Next, in a state where no object such as the finger 202 is brought into contact with the fingerprint reading surface 107 in advance, the image pickup device 105 is driven to perform photoelectric conversion of the light beam from the fingerprint reading surface 107 to capture an image (step S902). ).
[0128]
Next, the first output of the image sensor 105 is stored in a storage unit (not shown) such as a RAM or a buffer connected to or mounted on the image capturing apparatus 101 (step S903).
[0129]
Next, the fingerprint reading LED 108 is turned on again (step S904), and when it is detected that the finger 202 has come into contact with the fingerprint reading surface 107 (step S905), the image sensor 105 is driven (step S906). The light beam from the fingerprint reading surface 107 is photoelectrically converted to capture an image, and the second output from the image sensor 105 is stored in the storage unit (step S907).
[0130]
Step S904 is unnecessary when the fingerprint reading LED 108 is continuously turned on.
[0131]
Furthermore, the detection of the finger 202 in step S905 may be performed by a sensor such as an electrostatic sensor that detects contact, or may be configured to be detected by optically analyzing an image.
[0132]
Then, a difference process is performed between each pixel value of the first output and the second output from the image sensor 105 stored in the storage unit (step S908), and the image subjected to the difference process is stored in the storage unit (step S908). Step S909).
[0133]
By executing such steps for the image capturing apparatus 101, it is possible to correct the floating of the black level, and it is possible to obtain an image with high contrast required for authentication.
[0134]
Needless to say, these image correction methods can be implemented by a program for causing a computer to execute the above-described steps and a storage medium storing the program.
[0135]
In the embodiment of the present invention, the information represented by the unevenness is not limited to a fingerprint, and includes, for example, Braille information, and the information represented by shading is not limited to a document. Needless to say.
[0136]
【The invention's effect】
As described above, according to the image capturing apparatus of the present invention, an image capturing apparatus capable of capturing image information represented by unevenness such as a fingerprint, thin, easy to mount on an information device, and having excellent rigidity in the thickness direction. Equipment can be provided.
[Brief description of the drawings]
FIG. 1A is a schematic diagram illustrating an optical path of an image capturing apparatus according to a first embodiment of the present invention.
FIG. 2B is a perspective view illustrating a configuration of the image capturing apparatus according to the first embodiment of the present invention.
FIG. 2A is a partial cross-sectional view illustrating a structure of a prism unit viewed from a document reading surface according to the first embodiment of the present invention;
FIG. 4B is a diagram illustrating an intensity distribution of light rays on the fingerprint reading surface according to the first embodiment of the present invention.
FIG. 3A illustrates an example of a wavelength distribution of a document reading LED according to the first embodiment of the present invention.
(B) is a diagram showing light transmission with respect to the wavelength of the filter according to the first embodiment of the present invention.
FIG. 4A illustrates an example of a configuration of an image sensor according to the first embodiment of the present invention.
FIG. 2B is a diagram for explaining an exposure period of the image sensor according to the first embodiment of the present invention.
FIG. 4C is a diagram illustrating an example of an image captured by the image capturing device according to the first embodiment of the present invention.
FIG. 5A is a partial side view of a flexible substrate according to the first embodiment of the present invention.
(B) is a schematic perspective view showing the structure of the flexible substrate according to the first embodiment of the present invention.
(C) is a schematic plan view illustrating the generation of stress of the flexible substrate according to the first embodiment of the present invention.
FIG. 6A is a schematic cross-sectional view illustrating a configuration of an image capturing apparatus according to a second embodiment of the present invention.
(B) is a schematic plan view showing the structure of the prism unit according to the second embodiment of the present invention.
FIG. 7A is a front view of a mobile phone equipped with the image capturing device according to the first embodiment of the present invention.
FIG. 2B is a perspective view of a main part of a mobile phone equipped with the image capturing apparatus according to the first embodiment of the present invention.
FIG. 8A is a partial cross-sectional view illustrating a structure of a prism unit according to a third embodiment of the present invention.
FIG. 14B is a diagram illustrating an example of an output level from the image sensor when a finger is brought into contact with the third embodiment of the present invention.
FIG. 9C is a diagram illustrating an example of an output level from the image sensor when the finger is not in contact with the third embodiment of the present invention.
(D) is a diagram showing an example in which the output from the image sensor according to the third embodiment of the present invention has been corrected.
FIG. 9 is a flowchart illustrating processing steps of an image correction method according to a third embodiment of the present invention.
[Explanation of symbols]
50 Mobile phone device
51 Antenna part
52 Speaker section
53 Display
54 key part
55 Microphone
101,601 Image photographing device
102,602 Prism section
103 Optical block
104 graded index lens
105 Image sensor
106 case
107 Fingerprint reading surface
108 Fingerprint reading LED
109 Light leakage prevention film
110 mirror surface
111 Flexible board
112 External connection terminal
113 Document reading surface
114 Document reading LED
115 sealing material
150 Original light source reflective surface
161 Opposing surface
162 emission surface
181 Side view of gradient index lens
182 Mold resin
183 lens section
201 Transparent material
202 fingers
205 Light source reflective surface for fingerprint
251 Photodiode
252 partial image
401 Image sensor mounting terminal

Claims (33)

A prism unit including a first surface to which a first imaging target is to be brought into contact and a second surface facing the first surface;
A light source unit that generates a light beam to be incident on the prism unit,
A light-collecting unit that collects light beams emitted from the prism unit and forms an image at a predetermined position;
An imaging unit disposed at the predetermined position,
The second surface is formed to reflect a light beam incident on the prism unit from the light source unit and irradiate the first surface in a vertical direction from the inside,
An image photographing device, wherein the image photographing device is arranged so as to contact at least a part of a side surface of a member forming the light collecting section. A prism unit including a first surface to which a first imaging target is to be brought into contact and a second surface facing the first surface;
A light source unit that generates a light beam to be incident on the prism unit,
A light-collecting unit that collects light beams emitted from the prism unit and forms an image at a predetermined position;
An imaging unit disposed at the predetermined position,
The second surface is formed to reflect a light beam incident on the prism unit from the light source unit and irradiate the first surface in a vertical direction from the inside,
An image capturing apparatus, wherein a support member that supports the prism unit and the light collecting unit is disposed between the second surface and a side surface of a member that forms the light collecting unit. The image photographing apparatus according to claim 2, wherein the support member is a member that prevents light from leaking from the prism portion or a member that reflects a light beam emitted from the prism portion to the prism portion. . A reflecting surface configured so that the first surface and the optical axis center of the light collecting unit are parallel to each other, and reflecting light rays from the first surface in a direction coinciding with the optical axis direction of the light collecting unit The image photographing apparatus according to any one of claims 1 to 3, wherein the image capturing device is provided in the prism unit. A half mirror surface is formed instead of the reflection surface on the surface of the prism portion where the reflection surface is to be formed,
The image of a second photographing object arranged on the opposite side of the half mirror surface on which the light-collecting portion is arranged is photographed by a light beam transmitted through the half mirror surface. An image capturing apparatus according to the above. The image photographing apparatus according to claim 1, wherein an exit surface of the prism unit and an entrance surface of the light collection unit are in close contact with each other. The image capturing apparatus according to any one of claims 1 to 6, wherein the light collecting unit is a gradient index lens. The image capturing device according to claim 1, wherein the light source unit includes a light emitting diode. An irradiation light source unit for irradiating the second imaging target is provided, and a filter for selectively transmitting a wavelength of a light beam reflected from the second imaging target is provided on the half mirror surface. The image photographing device according to any one of claims 5 to 8. The apparatus according to claim 9, wherein the filter selectively transmits light having a wavelength within a range of 50 nm or more and 150 nm or less, including a light wavelength generated by the irradiation light source unit. The image capturing device according to claim 1, wherein the image capturing unit is a CMOS sensor. The image capturing apparatus according to claim 11, wherein the CMOS sensor simultaneously starts exposure of all pixels and performs exposure for the same period. The surface of the prism unit facing the irradiation light source unit reflects light emitted from the irradiation light source unit and irradiates the light to the second object to be photographed. The image photographing device according to any one of the above. A terminal for connecting the imaging unit of the image capturing device and a device in which the image capturing device is to be incorporated is disposed on a surface of the image capturing device that is to be in contact with a housing of the device in which the image capturing device is to be incorporated. When the image capturing device is incorporated in the housing, the terminal and the terminal formed on the housing come into contact with each other, whereby the terminal and the terminal formed on the housing are electrically connected. The image photographing apparatus according to any one of claims 1 to 13, characterized in that: The imaging unit and the terminal configured in the image capturing device are connected by a flexible substrate, and the flexible substrate is sandwiched between the image capturing device and the housing of the device in which the image capturing device is to be incorporated. The image capturing apparatus according to claim 14, wherein the image capturing apparatus is fixed. The image capturing apparatus according to claim 15, wherein a slit is formed on the flexible substrate. The image photographing apparatus according to any one of claims 1 to 16, wherein a sealing process is performed on a portion where the prism unit and a housing holding the prism unit are in contact with each other. 18. The image capturing apparatus according to claim 17, wherein a material used for the sealing process is a waterproof adhesive material. 19. The image photographing apparatus according to claim 1, wherein the first photographing target is a finger, and the second photographing target is a document. An information device comprising the image photographing device according to any one of claims 1 to 19. A contact surface that the subject should contact,
The entrance surface where the light rays should enter,
An emission surface from which the light beam is to be emitted,
A first reflecting surface formed with a reflecting portion for reflecting a light beam incident from the incident surface toward the contact surface,
An optical element, comprising: a second reflection surface that reflects a light beam from the contact surface toward the emission surface. 22. The optical element according to claim 21, wherein the first reflection surface is processed so that a cross section thereof has a saw-tooth shape, thereby forming the reflection portion. 23. The optical element according to claim 21, wherein the reflection portion is coated with a reflection film made of a high reflectance member. The optical element according to claim 23, wherein the high reflectivity member is aluminum. 25. The optical element according to claim 23, wherein the reflection film is formed such that the reflectance of the reflection film increases as the distance from the incident surface increases. The optical element according to any one of claims 21 to 25, wherein the optical element is made of plastic. The optical element according to any one of claims 21 to 25, wherein the optical element is made of glass. 22. An angle between an optical path from the center of the contact surface to the center of the second reflection surface and an optical axis of a light beam emitted from the emission surface is 46 degrees or less. 28. The optical element according to claim 27. The light leakage prevention film is formed on a surface other than the incident surface, the emission surface, the contact surface, the first reflection surface, and the second reflection surface. The optical element according to any one of the above. An image photographing apparatus comprising the optical element according to any one of claims 21 to 29. An information device comprising the image photographing device according to claim 30. An image correction method in an image capturing apparatus that captures an image by contacting a capturing target with a contact surface,
An image correction method, comprising: correcting an image captured by bringing the imaging target into contact with the contact surface using an image captured without bringing the imaging target into contact with the contact surface. The correction is performed by performing a difference process between an image photographed by bringing the photographing target into contact with the contact surface and an image photographed without contacting the photographing target with the contact surface. The image correction method according to claim 32, wherein:

Images