JP2009105601A - Imaging apparatus, biological information acquiring device, and mobile communication terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that the quality of an acquired image is deteriorated by the effect of diffused external light. <P>SOLUTION: An imaging apparatus 60 images an image inputted to a surface area from an outside world. The imaging apparatus 60 is provided with a dimming means for setting light transmittance in a plurality of respective unit areas defined by dividing the surface area on the basis of light transmittance and electrical control previously set according to the incident light intensity of each surface area, and a photodetector 20 having a plurality of pixels for receiving light that transmits the unit areas set to prescribed light transmittance. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an imaging device, a biological information acquisition device, and a mobile communication terminal.

  In recent years, the development of technology related to biometric authentication has been remarkable. Biometric authentication is a technique for identifying a certain individual from other individuals based on the determination whether the biometric information acquired from the individual to be examined is equal to biometric information set in advance. For example, there are a method for identifying an individual based on the iris of a human pupil, a method for identifying an individual based on a vein pattern such as a human finger, and a method for identifying an individual based on a fingerprint pattern of a finger. Among them, those using vein patterns such as human fingers are difficult to disguise pattern data, and high security can be ensured.

Patent Document 1 discloses an imaging device used for biometric authentication. In this imaging apparatus, the imaging apparatus is downsized by stacking the light source (100), the support base (300), and the image authentication unit (200).
JP 2001-119008 A

  By the way, when a biometric authentication device is incorporated in an information device such as a mobile communication terminal, biometric authentication can be executed not only indoors but also outdoors. In such a case, there is a possibility that light having an intensity outside the allowable range may be input to the pixels of the image sensor due to the superposition of sunlight. When light having an intensity outside the allowable range is input to the pixel, the pixel is saturated and the acquired image is partially whitened. Even if it is partial, if the image quality deteriorates, it may be determined that the authentication is failed even if it is determined that the authentication is successful, and as a result, the reliability of the biometric authentication device is lost.

  The present invention has been made to solve such problems, and it is an object of the present invention to suppress deterioration of the quality of an acquired image due to the influence of ambient light.

  An imaging apparatus according to the present invention is an imaging apparatus that captures an image input to a surface area from the outside, and the light transmittance in each of a plurality of unit areas defined by dividing the surface area is expressed as the unit. Light control means for setting light transmittance set in advance according to the incident light intensity for each region based on electrical control, and a plurality of light receiving light that has passed through the unit region set to a predetermined light transmittance A photodetector having a plurality of pixels.

  By setting the light transmittance for each unit area by the light control means, it is possible to suppress saturation of the pixels of the photodetector as light having an intensity exceeding an allowable range is input. As a result, a high-quality image can be acquired even in a place where high intensity disturbance light is incident.

  The dimming means is configured to set the unit based on setting a plurality of unit electrodes provided corresponding to each of the plurality of unit regions to a voltage set in advance according to the incident light intensity for each unit region. It is preferable to control the light transmittance for each region.

  The dimming means includes a liquid crystal layer, a pair of electrode layers sandwiching the liquid crystal layer with the plurality of unit electrodes as upper electrodes or lower electrodes, and a voltage setting unit for setting each of the plurality of unit electrodes to a predetermined voltage. It is good to have.

  It is preferable to further include light guiding means for guiding light that has passed through the unit region to the plurality of pixels.

  Each of the plurality of unit electrodes is preferably set to a preset voltage sequentially.

  The light guiding means may be an optical member that guides input light to the pixel through a plurality of reflecting surfaces.

  The optical member may be composed of a plurality of guide members arranged adjacent to each other.

  The plurality of guide members may be disposed on the photodetector, and the liquid crystal layer may be disposed on the plurality of guide members.

  A pair of polarizing plates that sandwich the pair of electrode layers may be further provided.

  It is preferable to further include a plurality of lenses that are disposed on the liquid crystal layer and collect input light.

  The liquid crystal layer may be formed in the same layer as a liquid crystal layer of a liquid crystal display device disposed adjacent to the imaging device.

  The photodetector may be a line sensor in which a plurality of the pixels are arranged in one row.

  An imaging apparatus according to the present invention is an imaging apparatus that captures an image input from the outside to a surface area, and is provided corresponding to a liquid crystal layer and a plurality of unit areas defined by dividing the surface area. A pair of electrode layers sandwiching the liquid crystal layer with a plurality of unit electrodes as upper electrodes or lower electrodes, and setting the unit electrodes to a voltage set in advance according to the incident light intensity for each unit region And a photodetector having a plurality of pixels that receive light passing through the unit region set to a predetermined light transmittance.

  By utilizing the liquid crystal technology as the light control means, saturation of the pixels of the photodetector with the input of light with an intensity exceeding the allowable range is suppressed. As a result, a high-quality image can be acquired even in a place where high intensity disturbance light is incident.

  A biological information acquisition apparatus according to the present invention is a biological information acquisition apparatus that acquires biological information of the subject based on light irradiation on the subject, and a light source that emits light to be irradiated on the subject; The light transmittance in each of a plurality of unit regions defined by dividing the surface region into which the reflected light or the transmitted light is input and the surface region is preset according to the incident light intensity for each unit region. A light control means for setting the light transmittance based on electrical control, and a photodetector having a plurality of pixels that receive light that has passed through the unit region.

  By setting the light transmittance for each unit area by the light control means, it is possible to suppress saturation of the pixels of the photodetector as light having an intensity exceeding an allowable range is input. As a result, a high-quality image can be obtained even in a place where high-intensity disturbance light is incident, and the reliability of biometric authentication can be ensured.

  The light control means may set the light transmittance in the unit region closer to the light source to be lower than the light transmittance in the unit region located farther from the light source.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress that the quality of an acquired image deteriorates by the influence of disturbance light.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Each embodiment is simplified for convenience of explanation. Since the drawings are simple, the technical scope of the present invention should not be interpreted narrowly based on the drawings. The drawings are only for explaining the technical matters, and do not reflect the exact sizes or the like of the elements shown in the drawings. The same elements are denoted by the same reference numerals, and redundant description is omitted. Words indicating directions such as up, down, left, and right are used on the assumption that the drawing is viewed from the front.

[First Embodiment]
A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic diagram showing a configuration of a mobile phone. FIG. 2 is a schematic diagram showing the configuration of the front surface of the mobile phone. FIG. 3 is an enlarged schematic diagram showing the configuration of the front surface of the mobile phone. FIG. 4 is a schematic exploded perspective view of the imaging apparatus. FIG. 5 is a schematic diagram illustrating a schematic cross-sectional configuration of the imaging apparatus. FIG. 6 is a schematic diagram for explaining the configuration of the front surface of the image sensor. FIG. 7 is a schematic diagram showing an arrangement mode of unit electrodes. FIG. 8 is a flowchart for explaining the operation of the biological information acquisition apparatus. FIG. 9 is a flowchart for explaining the operation of the biological information acquisition apparatus regarding voltage setting. FIG. 10 is a table showing specific examples of voltage setting conditions. FIG. 11 is an explanatory diagram showing a change in the relative light transmittance of the liquid crystal with respect to the applied voltage.

  FIG. 1 shows a mobile phone (mobile communication terminal) 50. The mobile phone 50 incorporates an imaging device 60 described later. In addition, the mobile phone 50 incorporates a biological information acquisition device using the imaging device 60.

  As shown in FIG. 1, the mobile phone 50 includes an upper body (first member) 51, a lower body (second member) 52, and a hinge 53. The upper main body 51 and the lower main body 52 are both plastic flat members and are connected via a hinge 53. The upper body 51 and the lower body 52 are configured to be freely opened and closed by a hinge 53. When the upper body 51 and the lower body 52 are closed, the mobile phone 50 is a flat plate member in which the upper body 51 and the lower body 52 are overlapped.

  The upper body 51 has a display unit 54 on the inner surface thereof. The display unit 54 displays information (name, telephone number) for identifying the called party, an address book stored in the storage unit of the mobile phone 50, and the like. A liquid crystal display device is incorporated under the display unit 54.

  The lower main body 52 has a plurality of buttons 55 on its inner surface. The operator of the mobile phone 50 operates the button 55 to open the address book, make a call, set the manner mode, and operate the mobile phone 50 as intended.

  As will be described later, the mobile phone 50 according to the present embodiment incorporates a biometric authentication device. The operator of the mobile phone 50 can turn on or off the biometric authentication function based on the operation of the button 55.

  FIG. 2 shows the configuration of the front surface (upper surface) of the mobile phone 50. As shown in FIG. 2, a surface region R <b> 10 and a display region R <b> 20 are disposed on the front surface of the upper main body 51.

  As schematically shown in FIG. 2, a finger (biological part) 57 of a human (subject) is placed on the surface region R10. An imaging device 60 (see FIG. 4), which will be described later, is disposed under the surface region R10. The imaging device 60 includes the liquid crystal layer 5 (see FIG. 4).

  In the display area R20, characters (time, operation state, destination name, etc.) are displayed. A liquid crystal display device is disposed under the display region R20. This liquid crystal display device is a general one including elements such as an upper electrode, a liquid crystal layer, and a lower electrode.

  As schematically shown in FIG. 2, a plurality of light sources 56 are arranged on the left and right of the surface region R10. The light source 56 emits light with a wavelength suitable for biometric authentication (orange to near-infrared band light (580 nm to 1000 nm, more preferably 600 nm to 900 nm)) toward the front. The light source 56 is, for example, a semiconductor optical device such as a semiconductor light emitting device (LED (Light Emitting Diode)) or a semiconductor laser device (LD (Laser Diode)).

  The biometric authentication device incorporated in the mobile phone 50 has a biometric information acquisition device as an interface part. This biological information acquisition apparatus includes an imaging device 60 and a light source 56.

  FIG. 3 shows an enlarged configuration of the front surface of the mobile phone 50. As shown in FIG. 3, the surface region R10 and the display region R20 are in a region R30 where the liquid crystal layer is present. In the present embodiment, the liquid crystal layer included in the imaging device 60 below the surface region R10 and the liquid crystal layer included in the liquid crystal display device below the display region R20 are located in the same layer and are manufactured in the same manufacturing process. Manufactured.

  By using a common member for the imaging device 60 under the surface region R10 and the liquid crystal display device under the display region R20, the cost required for incorporating the imaging device 60 into the mobile phone 50 can be reduced. In addition to the liquid crystal layer, the commonly used member may be a polarizing plate that sandwiches the liquid crystal layer, a transparent substrate that sandwiches the liquid crystal layer, a lower electrode, or an upper electrode. In either case, the common members are arranged in the same layer.

  FIG. 4 is a schematic exploded perspective view of the imaging device 60. Note that, as described above, the imaging device 60 is disposed under the surface region R10 and manufactured by a process common to the liquid crystal display device under the display region R20. FIG. 5 shows a schematic cross-sectional configuration of the imaging device 60.

  As shown in FIGS. 4 and 5, the imaging device 60 includes an imaging element (photodetector) 20, a polarizing plate 3, an electrode layer 4, a liquid crystal layer 5, an electrode layer 6, a polarizing plate 7, and a bandpass filter 70. Prepare in order. In addition, as illustrated in FIG. 4, the imaging device 60 includes a control unit 61, a storage unit 62, and a voltage setting unit 63. Note that the light control means in the present embodiment includes the electrode layer 4, the liquid crystal layer 5, the electrode layer 6, and the voltage setting unit 63.

  As schematically shown in FIG. 6, the imaging element 20 includes a plurality of pixels Px arranged in a two-dimensional manner on the light receiving surface 20 a. The imaging device 20 is a general imaging device such as a CCD (Charge Coupled Device) sensor, a CMOS (Complementary Metal Oxide Semiconductor) sensor, or a TFT (Thin Film Transistor) sensor.

  The polarizing plate 3 is an optical member that transmits light of a specific polarization component. Similarly to the polarizing plate 3, the polarizing plate 7 is an optical member that transmits light of a specific polarization component.

  The electrode layer (lower electrode) 4 is made of a conductive thin film (ITO: Indium Tin Oxide) and is substantially transparent to light in a visible light to near infrared band. The electrode layer (upper electrode) 6 is the same as the electrode layer 4. An electric field is applied to the liquid crystal layer 5 by applying a voltage between a pair of electrode layers composed of the electrode layer 4 and the electrode layer 6. The alignment state of the liquid crystal in the liquid crystal layer 5 is controlled by applying an electric field. As shown in FIG. 4, the electrode layer 4 is connected to the anode of the power source E1, and the electrode layer 6 is connected to the cathode of the power source E1 through the voltage setting unit 63.

  The band-pass filter 70 selectively transmits light having a wavelength suitable for biometric authentication (orange to near-infrared band light (580 nm to 1000 nm, more preferably 600 nm to 860 nm)).

  As shown in FIG. 5, the electrode layer 6 includes unit electrodes 6a to 6e. Each unit electrode is connected to a voltage setting unit 63. When acquiring an image used for biometric authentication, the voltage setting unit 63 sets each unit electrode to a preset voltage. In other words, the voltage set for each unit electrode by the voltage setting unit 63 is applied to each unit electrode. The voltage applied to each unit electrode is preset according to the amount of incident light in each unit region (described later). This point will become clear from the following description.

  As shown in FIG. 5, a spacer 8 is disposed between the electrode layer 4 and the electrode layer 6. The space formed between the electrode layer 4 and the electrode layer 6 by the spacer 8 is filled with the liquid crystal layer 5.

  As illustrated in FIG. 4, the imaging device 60 includes a control unit 61, a storage unit 62, and a voltage setting unit 63. The control unit 61 is connected to the image sensor 20, the voltage setting unit 63, and the storage unit 62. The voltage setting unit 63 is connected between the electrode layer 6 and the power source E1. The controller 61 includes a CPU (Central Processing Unit). The storage unit 62 is a semiconductor memory that has a function of temporarily holding data. The voltage setting unit 63 is a functional block (functional circuit) that sets the voltage supplied from the power source E <b> 1 for each unit electrode included in the electrode layer 6. In addition, the control part 61, the memory | storage part 62, and the voltage setting part 63 are normally integrated in integrated circuits, such as ASIC (Application Specific Integrated Circuit).

  FIG. 7 shows how the unit electrodes are arranged. As shown in FIG. 7, the surface region R10 is divided into five by axis lines (first axis lines) L1 to L4, and unit regions R1 to R5 are defined. The unit area is an area defined by dividing the surface area by a plurality of axes. As shown in FIG. 7, the unit region R1 below the axis L1, the unit region R2 between the axis L1 and the axis L2, the unit region R3 between the axis L2 and the axis L3, the unit region R4 between the axis L3 and the axis L4, A unit region R5 is formed above the axis L4.

  The unit electrodes 6a to 6e constituting the electrode layer 6 are provided corresponding to the unit regions R1 to R5. That is, the unit electrode 6a is provided corresponding to the unit region R1. The unit electrode 6b is provided corresponding to the unit region R2. The unit electrode 6c is provided corresponding to the unit region R3. The unit electrode 6d is provided corresponding to the unit region R4. The unit electrode 6e is provided corresponding to the unit region R5.

  As shown in FIG. 7, a plurality of light sources 56 are arranged around the surface region R10. Two light sources 56a and 56b are arranged above the unit region R5. Two light sources 56c and 56d are arranged below the unit region R1. The arrangement direction of the light sources 56a and 56b is substantially parallel to the longitudinal direction of the unit electrodes 6a to 6e. The same applies to the light sources 56c and 56d.

  In the present embodiment, when acquiring an image used for biometric authentication, the voltage setting unit 63 sets each of the unit electrodes 6a to 6e to a voltage set in advance according to the incident light intensity for each unit region. By setting the voltage in this way, the light transmittance of the liquid crystal layer under the unit electrode can also be set to a light transmittance set in advance according to the incident light intensity for each unit region. Thereby, even if it is a place where high-intensity disturbance light is incident, a high-quality image can be acquired and the reliability of biometric authentication can be ensured. Note that the image sensor 20 captures an image input to the surface region R10 based on light that has passed through the unit region set to a predetermined light transmittance.

  In this way, by setting the light transmittance of the liquid crystal layer for each unit region, even if light outside the allowable range is partially incident due to the disturbance light being superimposed, deterioration of the acquired image is effectively suppressed. The Note that suppressing image degradation is realized by setting the light transmittance of a unit region where light outside the allowable range is incident low.

  FIG. 8 is a flowchart for explaining the biometric authentication operation of the mobile phone 50. When the finger 57 is placed on the surface region R10 of the non-operating mobile phone 50, the mobile phone 50 activates the biometric authentication function (S1). A mechanism for detecting that the finger 57 is placed on the surface region R10 is arbitrary. The operator himself / herself may activate the biometric authentication function by operating a button or the like.

  Next, the biometric information acquisition apparatus incorporated in the mobile phone 50 with the activation of the biometric authentication function sets a voltage condition (S2). The specific contents of the voltage condition setting will be described later with reference to FIG. A predetermined voltage is applied to each unit electrode according to the voltage condition.

  Next, the biological information acquisition device acquires a vein pattern (S3). There is a vein inside the finger 57, and the inspection light is absorbed by the vein. The inspection light is not absorbed so much in living tissues other than veins. Therefore, when the finger 57 is imaged based on the light transmitted through the finger 57, the portion corresponding to the vein is black, and a pattern reflecting the vein pattern is captured. Based on such a principle, the biological information acquisition apparatus images a vein pattern.

  Next, the biometric authentication device determines whether the acquired vein pattern (acquired pattern) matches the vein pattern (master pattern) registered in advance (S4). This determination is executed by a calculation unit incorporated in the biometric authentication device according to a predetermined algorithm.

  If the determination is successful, the mobile phone 50 activates the normal function of the mobile phone 50 (S5). For example, the mobile phone 50 releases the lock mode. If the determination is unsuccessful, the mobile phone 50 maintains a non-operating state.

  With reference to FIG. 9, the operation of setting the voltage condition described above will be described.

  First, the biological information acquisition apparatus emits inspection light to a biological part (S1). Specifically, the light source 56 is driven, and inspection light is emitted from the light source 56 forward.

  Next, the biological information acquisition device acquires an image (S2). Specifically, an image input via the surface region R <b> 10 is captured by the image sensor 20.

  Next, the biometric information acquisition apparatus executes a predetermined algorithm (S3), and checks whether image information is degraded (S4). Specifically, the control unit 61 applies a predetermined algorithm to the image information output from the image sensor 20, and determines whether the pixels of the image sensor 20 are saturated with incident light having an intensity outside the allowable range. inspect. The specific content of the algorithm is arbitrary. By applying an algorithm, it is preferable to check whether the pixel is saturated beyond a predetermined range and in which unit region the pixel is saturated.

  When there is no deterioration in the image information, the vein pattern is acquired under normal conditions. The normal conditions are, for example, as shown in FIG.

  On the other hand, when there is degradation in the image information, the vein pattern is acquired under the conditions at the time of degradation. The conditions at the time of deterioration are as shown in FIG.10 (b), for example.

  Here, a normally white method is adopted in which the light transmittance of the liquid crystal is lowered in accordance with voltage application. As shown in FIG. 11, the relative light transmittance of the liquid crystal of the liquid crystal layer 5 decreases as the applied voltage increases. Note that the light transmittance distribution of the liquid crystal has an effective range (range between dotted lines in FIG. 26) in which the light transmittance changes rapidly according to the applied voltage.

  In FIG. 10A, a voltage is applied to the unit electrodes 6a and 6e. This is because the unit electrode 6a is disposed closer to the light sources 56c and 56d than the unit electrode 6b, so that light having a higher intensity than the unit region R2 is incident on the unit region R1. Similarly, since the unit electrode 6e is disposed closer to the light sources 56a and 56b than the unit electrode 6d, light having a higher intensity than the unit region R4 is incident on the unit region R5. By setting in this way, saturation of pixels near the light source 56 is suppressed.

  In FIG. 10B, a voltage is applied to all the unit electrodes 6a to 6e. This is because as a result of applying the algorithm of S3, the image quality has deteriorated over the entire area of the image acquired in S2.

  Note that the conditions at the time of deterioration are not limited to those shown in FIG. 10B, and are appropriately set according to the degree of image deterioration. For example, if the image is degraded corresponding to only the unit region R3, the voltage 3V may be applied only to the unit electrode 6c. Further, the specific value of the applied voltage is appropriately set in consideration of the characteristics of the liquid crystal material.

  When performing biometric authentication outdoors, sunlight is also input to the image sensor 2. When sunlight is superimposed, each pixel of the image sensor 20 may be saturated. If the pixels of the image sensor 20 are partially saturated, the finally obtained image will appear partially white and it will be difficult to recognize the vein pattern. As a result, the reliability of biometric authentication is lost.

  In the present embodiment, the light transmittance in the unit region where light with an intensity exceeding the allowable range is incident is reduced according to the incident light intensity for each unit region. In other words, light input to each unit region is dimmed according to the degree of deterioration of the acquired image so that the pixels of the photodetector are not saturated. In this way, the saturation of the pixels of the photodetector is suppressed, and as a result, a high-quality image can be obtained at an arbitrary place and the reliability of biometric authentication can be ensured.

  Further, as is clear from the above description, incident light is dimmed by utilizing existing liquid crystal display technology. Specifically, the light transmittance of the unit region is set to a predetermined value by setting the voltage applied to the unit electrode to a predetermined value. It is also possible to obtain a higher quality image by controlling the light transmittance of the unit region with high accuracy.

  Further, the light transmittance of the unit region closer to the light source is set lower than the light transmittance of the unit region farther from the light source. Accordingly, the light source can be arranged in the vicinity of the surface region R10 to reduce the size of the biological information acquisition apparatus. Moreover, since the imaging device 60 can be assembled by laminating a liquid crystal display mechanism on the imaging element 20, it is easy to manufacture.

[Second Embodiment]
A second embodiment of the present invention will be described with reference to FIGS. FIG. 12 is a schematic exploded perspective view of the imaging apparatus. FIG. 13 is a schematic diagram showing an arrangement mode of unit electrodes. FIG. 14 is a schematic diagram for explaining the positional relationship among pixels, unit electrodes, guide members, and the like. FIG. 15 is a schematic diagram illustrating a schematic cross-sectional configuration of the imaging apparatus. FIG. 16 is a timing chart for explaining the operation of the imaging apparatus. In the following description, the description overlapping with the first embodiment is omitted in principle.

  In the present embodiment, the light transmitted through the liquid crystal layer 5 is guided to the pixels of the line sensor 1 through the light guide 2. By adopting such a configuration, the number of pixels required to capture a desired image can be significantly reduced. The same effect as that of the first embodiment can also be obtained.

  As shown in FIG. 12, the imaging device 60 includes a line sensor (photodetector) 1, a light guide layer 2, a polarizing plate 3, an electrode layer 4, a liquid crystal layer 5, an electrode layer 6, a polarizing plate 7, and a bandpass filter. 70 in this order. Furthermore, the imaging device 60 includes a control unit 61, a storage unit 62, and a voltage setting unit 63.

  The line sensor 1 is a photodetector in which a plurality of pixels are arranged in one row. The line sensor 1 is a PD array sensor in which photodiodes are arranged in a row, a MOS array sensor in which MOS (Metal Oxide Semiconductor) type pixels are arranged in a row, or the like.

  The light guide layer 2 is an optical member composed of a plurality of guide members 2a to 2f (see also FIG. 14) arranged corresponding to each pixel of the line sensor 1. The guide members 2a to 2f are optical members that are substantially transparent to the inspection light. The structure of each guide member 2a-2f which comprises the light guide layer 2 is mentioned later.

  Other members such as a polarizing plate are the same as those in the first embodiment.

  FIG. 13 shows how the unit electrodes are arranged. Similar to the arrangement mode of the unit electrodes 6a to 6e, the line sensor 1 is arranged under the surface region R10. The arrangement range of the pixels PXa to PXe is set corresponding to the setting range of the unit regions R1 to R5 described above. As a result, it is possible to acquire an image for each unit area without omission.

  FIG. 14 shows an arrangement relationship between the unit electrodes 6a to 6e, the guide members 2a to 2f, and the pixels PXa to Pxf. Each guide member guides light input from the upper surface to the pixel through the reflection surface. The configuration of each guide member will be described later.

  As shown in FIG. 14, the unit electrodes 6a to 6e are long electrodes extending along the y-axis. The line sensor 1 is also a long member that extends along the y-axis. The pixels PXa to PXf formed in the line sensor 1 are arranged along the y axis. Thus, the line sensor 1 and the unit electrodes 6a to 6e are arranged in parallel to each other. In other words, the line sensor 1 and the unit electrodes 6a to 6e are arranged in the order of the line sensor 1, the unit electrode 6a, the unit electrode 6b,... .

  The guide member 2a is an optical member that is long along the x-axis orthogonal to the y-axis. One end of the guide member 2a is disposed on the pixel PXa. The guide member 2a is disposed below the pixel PXa, the unit electrode 6a, the unit electrode 6b, the unit electrode 6c, the unit electrode 6d, and the unit electrode 6e.

  Here, a region where the guide member 2a and the unit electrode 6a are overlapped is defined as a region R1a. A region where the guide member 2a and the unit electrode 6b are overlapped is defined as a region R2a. A region where the guide member 2a and the unit electrode 6c are overlapped is defined as a region R3a. A region where the guide member 2a and the unit electrode 6d are overlapped is defined as a region R4a. A region where the guide member 2a and the unit electrode 6e are overlapped is defined as a region R5a.

  About the other guide members 2b-2f, it is the same as that of description of the guide member 2a. The names given to the regions where the guide members and the unit electrodes are overlapped are as shown in FIG.

  FIG. 15 shows a schematic cross-sectional configuration of the imaging device 60.

  The guide member 2a included in the light guide layer 2 has a flat front surface, but has a plurality of grooves 10 formed on the back surface. The groove 10 extends toward the paper surface or in the depth direction (extends along the y-axis). By forming the plurality of grooves 10 on the back surface of the guide member 2a, a plurality of reflecting surfaces (first reflecting surfaces) 11 and 12 are formed on the back surface of the guide member 2a. The guide member 2a has a reflective surface (second reflective surface) 13 at the left end portion thereof. The reflective surface 13 is disposed on the pixels of the line sensor 1. About the guide members 2b-2f, it is the same as that of description of the guide member 2a.

  With reference to FIG. 15, the light propagation path in the imaging device 60 will be described. Here, for convenience of explanation, it is assumed that the imaging device 60 employs a normally black method in which the transmittance increases in accordance with voltage application. Moreover, the voltage setting part 63 shall apply a predetermined voltage only to the unit electrode 6d. At this time, it is assumed that the unit region R4 is set to a region that transmits the input light (transmission region). At this time, the other unit regions R1 to R3 and the unit region R5 are set to regions that do not transmit input light (non-transparent regions). In addition, when acquiring the image used at the time of biometrics authentication, the preset voltage shall be applied to each unit electrode similarly to 1st Embodiment.

  The light emitted from the light source 56 and transmitted through the finger 57 is input to the unit region R4 of the surface region R10. As described above, the unit region R4 is set to a transmission region having a predetermined light transmittance. Therefore, the light input to the unit region R4 sequentially passes through the polarizing plate 7, the electrode layer 6, the liquid crystal layer 5, the electrode layer 4, and the polarizing plate 3. The light that has passed through the polarizing plate 3 is input to the guide member 2a through the upper surface of the guide member 2a. The light input to the guide member 2a is set so as to travel toward the left end of the guide member 2a by the reflecting surface 12 provided on the back surface thereof. That is, the light reflected by the reflection surface 12 of the guide member 2a travels toward the left end of the guide member 2a while repeating reflection at the interface between the guide member 2a and the polarizing plate 3 and reflection at the reflection surfaces 11 and 12. To do.

  A reflective surface 13 is provided at the left end of the guide member 2a. Therefore, the light that has traveled through the guide member 2a is reflected by the reflecting surface 13 and is input to the pixel PXa of the line sensor 1 disposed therebelow. Thus, the guide member 2a guides the light input via the front surface to the pixel PXa of the line sensor 1 via the reflection surface. This is the same when a unit region other than the unit region R4 is selected as the transmissive region. Note that the description of the guide member 2a also applies to the other guide members 2b to 2f.

  FIG. 16 is a timing chart for explaining the operation of the imaging device 60.

  As illustrated in FIG. 16, the imaging device 60 sequentially selects the unit electrodes 6a to 6e according to the passage of time from t1 to t7, and sets any one of the unit regions R1 to R5 as a transmission region. The line sensor 1 detects an image for each of the unit regions R1 to R5. This makes it possible to acquire the entire image finally input to the surface region R10. In addition, when acquiring the image used at the time of biometrics authentication, the preset voltage shall be applied to each unit electrode similarly to 1st Embodiment. That is, the voltage applied to each unit electrode may not be a constant voltage between the unit electrodes. The voltage applied to each unit electrode is set according to the incident light intensity of each unit region.

  A control signal 001 is transmitted from the control unit 61 to the voltage setting unit 63 between times t1 and t2. At this time, the voltage setting unit 63 applies a predetermined voltage (3 V in FIG. 10B) to the unit electrode 6a. Thereby, the unit region R1 is set to a transmission region having a predetermined light transmittance. Then, the light in the range of the region R1a (see FIG. 14) is guided to the pixel PXa. The light in the range of the region R1b is guided to the pixel PXb. The light in the range of the region R1c is guided to the pixel PXc. The light in the region R1d is guided to the pixel PXd. The light in the range of the region R1e is guided to the pixel PXe. Light in the range of the region R1f is guided to the pixel PXf.

  After a certain amount of detection time (or accumulation time) is secured, the control unit 61 outputs a read signal (output instruction signal) to the line sensor 1. The line sensor 1 outputs a digital signal indicating the amount of charge accumulated in each pixel to the control unit 61 based on the read signal. Then, the control unit 61 stores the image of the unit region R1 in the storage unit 62. Here, it is assumed that the line sensor 1 also includes an A / D (Analog / Digital) converter.

  A control signal 010 is transmitted from the control unit 61 to the voltage setting unit 63 between times t2 and t3. At this time, the voltage setting unit 63 applies a predetermined voltage (2 V in FIG. 10B) to the unit electrode 6b. Thereby, the unit region R2 is set to a transmission region having a predetermined light transmittance. Then, the light in the region R2a is guided to the pixel PXa. The light in the range of the region R2b is guided to the pixel PXb. The light in the range of the region R2c is guided to the pixel PXc. The light in the range of the region R2d is guided to the pixel PXd. The light in the range of the region R2e is guided to the pixel PXe. Light in the range of the region R2f is guided to the pixel PXf.

  After a certain amount of detection time (or accumulation time) is secured, the control unit 61 outputs a read signal to the line sensor 1. The line sensor 1 outputs a digital signal indicating the amount of charge accumulated in each pixel to the control unit 61 based on the read signal. Then, the control unit 61 stores the image of the unit region R2 in the storage unit 62.

  A control signal 011 is transmitted from the control unit 61 to the voltage setting unit 63 between times t3 and t4. At this time, the voltage setting unit 63 applies a predetermined voltage (2 V in FIG. 10B) to the unit electrode 6c. As a result, the unit region R3 is set to a transmission region having a predetermined light transmittance. Then, the light in the range of the region R3a is guided to the pixel PXa. The light in the region R3b is guided to the pixel PXb. The light in the range of the region R3c is guided to the pixel PXc. The light in the range of the region R3d is guided to the pixel PXd. The light in the range of the region R3e is guided to the pixel PXe. The light in the region R3f is guided to the pixel PXf.

  After a certain amount of detection time (or accumulation time) is secured, the control unit 61 outputs a read signal to the line sensor 1. The line sensor 1 outputs a digital signal indicating the amount of charge accumulated in each pixel to the control unit 61 based on the read signal. Then, the control unit 61 stores the image of the unit region R3 in the storage unit 62.

  The control signal 100 is transmitted from the control unit 61 to the voltage setting unit 63 between times t4 and t5. At this time, the voltage setting unit 63 applies a predetermined voltage (2 V in FIG. 10B) to the unit electrode 6d. Thus, the unit region R4 is set as a transmission region having a predetermined light transmittance. Then, the light in the region R4a is guided to the pixel PXa. Light in the range of the region R4b is guided to the pixel PXb. The light in the range of the region R4c is guided to the pixel PXc. The light in the range of the region R4d is guided to the pixel PXd. The light in the range of the region R4e is guided to the pixel PXe. Light in the range of the region R4f is guided to the pixel PXf.

  After a certain amount of detection time (or accumulation time) is secured, the control unit 61 outputs a read signal to the line sensor 1. The line sensor 1 outputs a digital signal indicating the amount of charge accumulated in each pixel to the control unit 61 based on the read signal. Then, the control unit 61 stores the image of the unit region R4 in the storage unit 62.

  The control signal 101 is transmitted from the control unit 61 to the voltage setting unit 63 between times t5 and t6. At this time, the voltage setting unit 63 applies a predetermined voltage (3 V in FIG. 10B) to the unit electrode 6e, whereby the unit region R5 is set to a transmission region having a predetermined light transmittance. Then, the light in the region R5a is guided to the pixel PXa. The light in the region R5b is guided to the pixel PXb. The light in the range of the region R5c is guided to the pixel PXc. The light in the range of the region R5d is guided to the pixel PXd. The light in the range of the region R5e is guided to the pixel PXe. Light in the range of the region R5f is guided to the pixel PXf.

  After a certain amount of detection time (or accumulation time) is secured, the control unit 61 outputs a read signal to the line sensor 1. The line sensor 1 outputs a digital signal indicating the amount of charge accumulated in each pixel to the control unit 61 based on the read signal. Then, the control unit 61 stores the image of the unit region R5 in the storage unit 62.

  By such a procedure, finally, the image acquired in each of the unit regions R1 to R5 is stored in the storage unit 62. The unit regions R1 to R5 are regions defined by dividing the surface region R10 by the axis lines L1 to L4. Therefore, the image input to the surface region R10 can be synthesized by reconstructing the images of the unit regions R1 to R5. This combining process is performed by the control unit 61.

  As is clear from the above description, in the present embodiment, light that has passed through the unit area set as the transmission area is input to each pixel of the line sensor 1 via the light guide layer 2. By sequentially shifting the unit area set as the transmission area and sequentially detecting the image for each unit area with the photodetector, the entire image input to the surface area can be captured. In this case, it is sufficient to set the number of pixels of the line sensor 1 according to the setting range of the unit area. Therefore, a desired image can be acquired using a photodetector having a smaller number of pixels.

  In the present embodiment, unit electrodes are arranged corresponding to the unit regions, and the voltage application range to the liquid crystal layer is controlled using the unit electrodes. Thereby, the unit area to be set as the transmissive area can be set to the intended range.

  In the present embodiment, the unit region can be set to be transmissive or non-transmissive by utilizing existing liquid crystal technology.

  Moreover, in this embodiment, the light which permeate | transmitted the unit area is guided to the pixel of the line sensor 1 using the several guide members 2a-2f. By adopting a plurality of individually divided guide members, the crosstalk of light between each region (for example, the regions R1a to R1f) can be effectively reduced as compared with the case where they are integrated. Can be suppressed. Moreover, the thickness of the imaging device 60 can be made sufficiently thin by using a plate-like optical member. Moreover, light can be guided to the line sensor 1 more efficiently by providing a plurality of reflecting surfaces on the back surface of the guide member.

  Also in the present embodiment, as in the first embodiment, the liquid crystal display device adjacent to the imaging device 60 is made common. Thereby, the cost required for incorporating the imaging device 60 into the mobile phone 50 can be reduced.

  Note that, as is apparent from the above description, the imaging device 60 is grasped as the imaging device itself and as an imaging part of the biological information acquisition device. Note that the biological information acquisition apparatus mainly captures still objects. Therefore, even if it takes a predetermined time (t1 to t7) to acquire an image to be input to the surface region R10 as in this embodiment, there is no practical problem.

  Finally, a method for manufacturing the imaging device 60 will be described. The guide members 2a to 2f are manufactured in advance by mold formation or the like. Further, the polarizing plate 3, the electrode layer 4, the liquid crystal layer 5, the electrode layer 6, the polarizing plate 7, and the band pass filter 70 are laminated in accordance with a normal method for manufacturing a liquid crystal device. Then, guide members 2a to 2f are arranged on the line sensor 1, and then liquid crystal components (polarizing plate 3, electrode layer 4, liquid crystal layer 5, electrode layer 6, laminated on the guide members 2a to 2f, And a component composed of the polarizing plate 7). In this way, the imaging device 60 is manufactured. Note that, as described above, the imaging device 60 is manufactured in the same process as the liquid crystal display device arranged adjacently.

[Third Embodiment]
A second embodiment of the present invention will be described with reference to FIGS. FIG. 17 is a schematic exploded perspective view of the imaging apparatus. FIG. 18 is a schematic diagram showing a positional relationship among unit electrodes, guide members, pixels, and lenses. FIG. 19 is a schematic diagram illustrating a schematic cross-sectional configuration of the imaging apparatus. 17 and 19, the configuration of the band pass filter 70 is omitted.

  Unlike the second embodiment, the imaging device 60 according to the present embodiment has a plurality of lenses 20 arranged in a matrix on the front surface of the polarizing plate 7 as shown in FIGS. Therefore, an image can be acquired in a wider range. Moreover, the crosstalk of the light between the area | regions (for example, R1a-R1f) prescribed | regulated by the guide members 2a-2f in a unit area | region can further be suppressed. In addition, by appropriately setting the focal position of the lens 20, it is possible to reduce the light propagation loss particularly in the light guiding layer 2 and improve the light utilization efficiency of the imaging device 60.

  The technical scope of the present invention is not limited to the above-described embodiment, and various other embodiments are conceivable. The number of unit areas to be set and the setting range are arbitrary. The imaging device itself can be applied to various uses other than the biometric authentication device. Moreover, the external device mounted is not limited to a portable device such as a mobile communication terminal. The observation target at the time of biometric authentication is not limited to a human finger, but may be the palm of a human hand or other part.

  The unit electrode to be selected is appropriately set according to a liquid crystal display method such as a normal black method or a normal white method. Instead of using the liquid crystal technology, the unit region may be set to be transmissive or non-transmissive by using an electro-optic crystal whose transparency changes according to the applied voltage. However, in this case, the liquid crystal display device under the adjacent display region R20 cannot be shared.

  The light guiding means is not limited to a guide member, and any light guiding means may be used as long as it guides light from a unit area set in the transmission area to the pixels of the light detection unit. The guide members 2a to 2f are not limited to individual members, and may be members formed integrally with them. Further, it is not always necessary to provide the pixels of the line sensor 1 and the guide members in a one-to-one relationship. One guide member may be assigned to a plurality of pixels. Specific materials for each member can be appropriately selected by those skilled in the art.

It is a schematic diagram which shows the structure of the mobile telephone which concerns on the 1st Embodiment of this invention. It is a schematic diagram which shows the structure of the front surface of the mobile telephone which concerns on the 1st Embodiment of this invention. It is an expansion schematic diagram which shows the structure of the front surface of the mobile telephone which concerns on the 1st Embodiment of this invention. 1 is a schematic exploded perspective view of an imaging apparatus according to a first embodiment of the present invention. 1 is a schematic diagram illustrating a schematic cross-sectional configuration of an imaging apparatus according to a first embodiment of the present invention. It is a schematic diagram for demonstrating the structure of the front surface of the image pick-up element which concerns on the 1st Embodiment of this invention. It is a schematic diagram which shows the arrangement | positioning aspect of the unit electrode which concerns on the 1st Embodiment of this invention. It is a flowchart for demonstrating operation | movement of the biometric information acquisition apparatus which concerns on the 1st Embodiment of this invention. It is a flowchart for demonstrating operation | movement of the biometric information acquisition apparatus regarding the voltage setting which concerns on the 1st Embodiment of this invention. It is a table | surface which shows the specific example of the voltage setting which concerns on the 2nd Embodiment of this invention. It is explanatory drawing which shows the change of the relative light transmittance of the liquid crystal with respect to the applied voltage which concerns on the 2nd Embodiment of this invention. It is a schematic exploded perspective view of an imaging device concerning a 2nd embodiment of the present invention. It is a schematic diagram which shows the arrangement | positioning aspect of the unit electrode which concerns on the 2nd Embodiment of this invention. It is a schematic diagram for demonstrating arrangement | positioning relationship of the pixel which concerns on the 2nd Embodiment of this invention, a unit electrode, and a guide member. It is a schematic diagram which shows schematic sectional structure of the imaging device which concerns on the 2nd Embodiment of this invention. 6 is a timing chart for explaining the operation of the imaging apparatus according to the second embodiment of the present invention. It is a schematic exploded perspective view of the imaging device concerning a 3rd embodiment of the present invention. It is a schematic diagram which shows the arrangement | positioning relationship of the unit electrode which concerns on the 3rd Embodiment of this invention, a guide member, a pixel, and lenses. It is a schematic diagram which shows schematic sectional structure of the imaging device which concerns on the 3rd Embodiment of this invention.

Explanation of symbols

60 Imaging Device 61 Control Unit 62 Storage Unit 63 Voltage Setting Units 6a to 6e Unit Electrode 20 Imaging Element 3 Polarizing Plate 4 Electrode Layer 5 Liquid Crystal Layer 6 Electrode Layer 7 Polarizing Plate 8 Spacer

Claims (19)

An imaging device that captures an image input to the surface area from the outside world,
The light transmittance in each of the plurality of unit regions defined by dividing the surface region is set based on electrical control to a light transmittance set in advance according to the incident light intensity for each unit region. Dimming means;
A photodetector having a plurality of pixels that receive light that has passed through the unit region set to a predetermined light transmittance;
An imaging apparatus comprising: The light control means includes
The light transmittance for each of the unit regions is set based on the voltage set in advance in accordance with the incident light intensity for each of the unit regions for each of the plurality of unit electrodes provided corresponding to the plurality of the unit regions. The imaging apparatus according to claim 1, wherein the imaging apparatus is controlled. The light control means includes
A liquid crystal layer;
A pair of electrode layers sandwiching the liquid crystal layer with the plurality of unit electrodes as upper electrodes or lower electrodes;
A voltage setting unit for setting each of the plurality of unit electrodes to a predetermined voltage;
The imaging apparatus according to claim 2, further comprising:   The imaging apparatus according to claim 1, further comprising: a light guiding unit that guides the light that has passed through the unit region to the plurality of pixels.   The imaging apparatus according to claim 4, wherein each of the plurality of unit electrodes is sequentially set to a preset voltage.   The imaging apparatus according to claim 4, wherein the light guiding means is an optical member that guides input light to the pixels through a plurality of reflecting surfaces.   The image pickup apparatus according to claim 6, wherein the optical member includes a plurality of guide members arranged adjacent to each other. The plurality of guide members are disposed on the photodetector,
The imaging apparatus according to claim 7, wherein the liquid crystal layer is disposed on a plurality of the guide members.   The imaging apparatus according to claim 3, further comprising a pair of polarizing plates that sandwich the pair of electrode layers.   The imaging apparatus according to claim 3, further comprising a plurality of lenses that are disposed on an upper layer of the liquid crystal layer and collect input light.   The imaging device according to claim 3, wherein the liquid crystal layer is formed in the same layer as a liquid crystal layer of a liquid crystal display device disposed adjacent to the imaging device.   The imaging device according to claim 1, wherein the photodetector is a line sensor in which a plurality of the pixels are arranged in one row. An imaging device that captures an image input to the surface area from the outside world,
A liquid crystal layer;
A pair of electrode layers sandwiching the liquid crystal layer with a plurality of unit electrodes provided corresponding to a plurality of unit regions defined by dividing the surface region as upper electrodes or lower electrodes;
A plurality of pixels that receive light passing through the unit region set to a predetermined light transmittance based on setting the unit electrode to a voltage set in advance according to the incident light intensity for each unit region; A photodetector;
An imaging apparatus comprising:   A mobile communication terminal comprising the imaging device according to claim 1. A biological information acquisition device that acquires biological information of the subject based on light irradiation on the subject,
A light source that emits light to be irradiated to the subject;
A surface region to which the reflected light or the transmitted light is input;
The light transmittance in each of the plurality of unit regions defined by dividing the surface region is adjusted based on electrical control to a light transmittance set in advance according to the incident light intensity for each unit region. Light means;
A photodetector having a plurality of pixels that receive light that has passed through the unit region;
A biological information acquisition device comprising: The light control means includes
The light transmittance for each of the unit regions is set based on the voltage set in advance in accordance with the incident light intensity for each of the unit regions for each of the plurality of unit electrodes provided corresponding to the plurality of the unit regions. The biological information acquisition apparatus according to claim 15, wherein the biological information acquisition apparatus is controlled. The light control means includes
A liquid crystal layer;
A pair of electrode layers sandwiching the liquid crystal layer with the plurality of unit electrodes as upper electrodes or lower electrodes;
A voltage setting unit for setting each of the plurality of unit electrodes to a predetermined voltage;
The biological information acquisition apparatus according to claim 16, comprising:   The light control means sets the light transmittance in the unit region near the light source to be lower than the light transmittance in the unit region at a position farther from the light source. The biological information acquisition apparatus according to any one of the above.   A mobile communication terminal comprising the biological information acquisition device according to any one of claims 15 to 18.

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