Abstract:
The present disclosure describes cameras having an optical channel that includes spatially separated sensors for sensing different parts of the optical spectrum. For example, in one aspect, an apparatus includes an image sensor module having an optical channel and including a multitude of spatially separated sensors to receive optical signals in the optical channel. The multitude of spatially separated sensors includes a first sensor operable to sense optical signals in a first spectral range, and a second sensor spatially separated from the first sensor and operable to sense optical signals in a second spectral range different from the first spectral range.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
       [0001]    The present applications claims the benefit of U.S. Provisional Patent Application No. 62/143,325 filed on Apr. 6, 2015. The contents of the earlier application are incorporated herein by reference in their entirety. 
     
    
     FIELD OF THE DISCLOSURE 
       [0002]    The present disclosure relates to cameras having an optical channel that includes spatially separated sensors for sensing different parts of the optical spectrum. 
       BACKGROUND 
       [0003]    Recent developments in camera and sensor technologies, such as consumer-level photography, is the ability of sensors to record both IR and color (e.g., RGB). Various techniques can be provided for joint IR and color imaging. One approach is to swap color filters on a camera that is sensitive to IR. Taking sequential images after swapping filters, however, can present challenges when imaging moving objects. Another approach is to use one camera dedicated to IR imaging and another camera for color imaging. Using two cameras, however, can result in higher costs, larger overall footprint, and/or misalignment of the IR and color images. 
       SUMMARY 
       [0004]    The present disclosure describes cameras having an optical channel that includes spatially separated sensors for sensing different parts of the optical spectrum. 
         [0005]    For example, in one aspect, an apparatus includes an image sensor module having an optical channel and including a multitude of spatially separated sensors to receive optical signals in the optical channel. The multitude of spatially separated sensors includes a first sensor operable to sense optical signals in a first spectral range, and a second sensor spatially separated from the first sensor and operable to sense optical signals in a second spectral range different from the first spectral range. 
         [0006]    Some implementations include one or more of the following features. For example, in some cases, the first spectral range is in a part of the spectrum visible to humans, and the second spectral range is in an infra-red part of the spectrum. Thus, the first spectral range can be in a RGB part of the spectrum. 
         [0007]    In some instances, an optical assembly is disposed over the spatially separated sensors, wherein the optical assembly has a circular cross-section in a plane parallel to an image plane of the image sensor module. Further, in some implementations, the first sensor is a rectangular array of pixels. The second sensor also can be a rectangular array of pixels. In some cases, a third sensor is spatially separated from the first and second sensors and is operable to sense optical signals in the second spectral range. The third sensor also can be a rectangular array of pixels. In some cases, the first sensor is larger than each of the second and third sensors (e.g., a pixel array that consumes more surface area). The second sensor can be located, for example, at one side of the first sensor, and the third sensor can be located at an opposite side of the first sensor. 
         [0008]    In some implementations, a transparent cover is disposed between the optical assembly and the sensors, wherein the transparent cover has a first thickness directly over the first sensor and a second different thickness directly over the other sensor(s). 
         [0009]    The image sensor module can be integrated, for example, into a host device that includes a display screen. The apparatus further can include a readout circuit, and one or more processors operable to generate an image for display on the display screen based on output signals from pixels in the first sensor when the host device is in a first orientation, and to perform iris recognition based on output signals from pixels in one of the other sensor(s) when the host device is in a second orientation. 
         [0010]    Another aspect describes a method performed by an apparatus such as those mentioned above. The method includes receiving a user input indicative of a request to acquire image data using the image sensor module. In response to receiving the user input, an image is generated and displayed on a display screen based on output signals from pixels in the first sensor if the host device is in a first orientation. On the other hand, if the host device is in a second orientation, iris recognition of the user is performed based on output signals from pixels in the second sensor. 
         [0011]    In some case, the method further includes displaying, on the display screen, an image based on the output signals from the pixels in the second sensor if the host device is in the second orientation. In accordance with some implementations, in the first orientation, the apparatus is oriented in a portrait format, and in the second orientation, the apparatus is oriented in a landscape format. The first sensor can be used, for example, to sense radiation in a part of the spectrum visible to humans, and the second sensor can be used, for example, to sense radiation in the infra-red part of the spectrum. 
         [0012]    In some implementations, the apparatus further includes an eye illumination source operable to illuminate a subject&#39;s eye with IR radiation. In some instances, the eye illumination source is operable to emit modulated IR radiation, for example, toward a subject&#39;s face. The apparatus can include a depth sensor (e.g., an optical time-of-flight sensor) operable to detect optical signals indicative of distance to the subject&#39;s eye and to demodulate the detected optical signals. The one or more processors can be configured to generate depth data based on signals from the depth sensor. In some cases, the one or more processors are configured to perform eye tracking based on the depth data. 
         [0013]    Providing spatially separated sensors for sensing different part of the optical spectrum (e.g., RGB and IR) in the same optical channel can be advantageous in some cases, because manufacturing costs can be reduced since the same optical assembly is used for signals in both parts of the spectrum. The arrangements described here also can allow areas of the image plane to be used more efficiently. In particular, areas of the image plane that otherwise would be unused can be used, e.g., for the IR sensors without increasing the overall footprint of the module. Some implementations can make it easier for a user to use a camera module in a host device for multiple applications, such as capturing and displaying a color imaging as well as for iris recognition. In some cases, a host device into which the camera module is integrated is more aesthetically pleasing because fewer holes are needed in the exterior surface of the host device. 
         [0014]    Other aspects, features and advantages will be readily apparent from the following detailed description, the accompanying drawings, and the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  illustrates an example of an image sensor module. 
           [0016]      FIG. 2  is a top view of an image plane indicating locations of electromagnetic sensors. 
           [0017]      FIG. 3  illustrates examples other components that can be used with the image sensor module. 
           [0018]      FIG. 4  illustrates a host device in a vertical orientation and operable in an image display mode. 
           [0019]      FIG. 5  illustrates the host device in a horizontal orientation and operable in an iris recognition mode. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    As illustrated in  FIGS. 1 and 2 , a packaged image sensor module  100  can provide ultra-precise and stable packaging for an image sensor  102  mounted on a substrate  104  such as a printed circuit board (PCB). An image circle  105  defines areas of the image sensor surface available, in principle, to serve as sensor areas. The sensor&#39;s image plane includes a first sensor  103 A composed of an array of photosensitive elements (i.e., pixels) that are sensitive to radiation in a first part of the electromagnetic spectrum (e.g., light in the visible part of the spectrum, about 400-760 nm). The sensor&#39;s image plane also includes at least one additional sensor  103 B composed of an array of pixels that are sensitive to radiation in a second part of the electromagnetic spectrum (e.g., infra-red (IR) radiation, &gt;760 nm). In the illustrated example, the IR sensors  103 B are spatially separated from the RGB sensor  103 A and thus are located in regions of the image circle  105  not covered by the RGB sensor  103 A. 
         [0021]    In the illustrated example, an optical assembly, including a stack  106  of one or more optical beam shaping elements such as lenses  108 , is disposed over the image sensor  102 . The lenses  108  can be disposed, for example, within a circular lens barrel  114  that is supported by a transparent cover  110  (e.g., a cover glass), which in turn is supported by one or more vertical spacers  112  separating the image sensor  102  from the transparent cover  110 . The vertical spacers  112  can rest directly (i.e., without adhesive) on a non-active surface of the image sensor  102 . The vertical spacers  112  can thus help establish a focal length for the optical assembly  106  and/or correct for tilt. 
         [0022]    As illustrated in the example of  FIG. 1 , one or more horizontal spacers  116  laterally surround the transparent cover  110  and separate the outer walls  118  of the module housing from the transparent cover  110 . The outer walls  118  can be attached, for example, by adhesive to the image sensor-side of the PCB  104 . Adhesive also can be provided, for example, between the side edges of the cover  110  and the housing sidewalls  118 . An example of a suitable adhesive is a UV-curable epoxy. 
         [0023]    In some cases the cover  110  is composed of glass or another inorganic material such as sapphire that is transparent to wavelengths detectable by the image sensor  102 . The vertical and horizontal spacers  112 ,  116  can be composed, for example, of a material that is substantially opaque for the wavelength(s) of light detectable by the image sensor  102 . The spacers  112 ,  16  can be formed, for example, by a vacuum injection technique followed by curing. Embedding the side edges of the transparent cover  110  with the opaque material of the horizontal spacers  116  can be useful in preventing stray light from impinging on the image sensor  102 . The outer walls  118  can be formed, for example, by a dam and fill process. 
         [0024]    In the illustrated example, the RGB sensor  103 A is a rectangular-shaped array of 2560×1920 pixels (i.e., 5 Mpix) at or near the center of the image circle  105 , whereas each IR sensor  103 B is a rectangular-shaped array of 640×480 pixels closer to the periphery of the image circle. In particular, each IR sensor  103 B is located adjacent a longer edge of the RGB sensor  103 A, and the longer edges of the IR sensors  103 B are parallel to the longer edges of the IR sensor  103 A. Such an arrangement can make use of space within the image circle  105  that would remain unused if only the rectangular-shaped RGB sensor  103 A were included. In some implementations, color filters are disposed over the sensor  103 A to selectively allow wavelengths in the visible part of the spectrum to pass, but to block or significantly attenuate IR radiation. On the other hand, IR pass filters can be provided over the other sensors  103 B. 
         [0025]    In some implementations, the size, shape or location of the sensors may differ the foregoing example. Likewise, although the illustrated example is designed with RGB and IR sensors  103 A,  103 B, in other instances, the spatially separated sensors may be sensitive to other spectral ranges that differ from one another. 
         [0026]    The sensors  103 A,  103 B can be implemented, for example, as CCDs or photodiodes. The RGB and IR sensors  103 A,  103 B can be implemented as devices formed in the same or different semiconductor or other materials. For example, in some instances, different semiconductor or other materials that maximize sensitivity to the respective wavelengths of interest can be used. Thus, a material that is particularly sensitive to radiation in the visible part of the spectrum can be used for the sensor  103 A, and a different material that is particularly sensitive to IR radiation can be used for the sensors  103 B. The spatially separated RGB and IR sensors  103 A,  103 B can be implemented, for example, in different integrated circuit chips from one another. 
         [0027]    To provide for different focal-lengths of the lenses  108  with respect to the different sensors  103 A and  103 B, the thickness of the transparent cover  110  can vary across its diameter. For example, in some instances, the region  110 A of the transparent cover  110  directly over the RGB sensor  103 A can be thicker than the regions  110 B directly over the IR sensors  103 B. More generally, the thickness of the one part of the transparent cover  110  over an active area of the image sensor  102  may differ from its thickness over another active area of the image sensor, depending on the different spectral ranges the sensors are designed to detect. 
         [0028]    Providing spatially separated sensors in the same optical channel, where the sensors are sensitive, respectively, to different spectral ranges, can be advantageous. First, using the same optical assembly for both the RGB and IR pixels can reduce the number of optical assemblies that otherwise would be needed. Further, the overall footprint of the module can be maintained relatively small since separate channels are not needed for sensing the color and IR radiation. At the same time, a given size image circle can be more used more efficiently by including multiple spatially separated sensors. 
         [0029]    In some instances, the module  100  is operable for iris recognition or other biometric identification. Iris recognition is a process of recognizing a person by analyzing the random pattern of the iris. In such implementations, as shown in  FIG. 3 , an IR eye-illumination source  130 , which can be integrated into the module  100  or separate from the module, is operable to emit IR radiation to the iris of a user&#39;s eye. Images of the user&#39;s iris can be captured using signals from the pixels in one of the IR sensors  103 B. The acquired images can be used as input into a pattern-recognition algorithm and/or other applications executed by the processing circuit  100  or other processor in a host device. Accordingly, the complex random patterns extracted from a user&#39;s iris or irises can be analyzed, for example, to identify the user. 
         [0030]    As further shown in  FIG. 3 , a read-out circuit  120  and control/processing circuit  122 , such as one or more microprocessor chips, can be coupled to the sensors  103 A,  103 B to control reading out and processing of the signals from the pixels. Depending on the application, the processing circuit  122  can perform one or more of the following: (i) generate a color image based on output signals from the pixels in the sensor  103 A for sensing radiation in the visible part of the spectrum; (ii) perform facial recognition based on output signals from the pixels in the sensor  103 A; (iii) generate an IR image based on the output signals from the pixels in the sensors  103 B for sensing radiation in the IR part of the spectrum; (iii) perform iris recognition based on output signals from one of the sensors  103 B for sensing IR radiation. 
         [0031]    As indicated by  FIGS. 4 and 5 , the compact, small footprint camera modules described here can be integrated, for example, into a host device such as a smart phone  200  or other small mobile computing devices (e.g., tablets, personal data assistants (PDAs), notebook computers; laptop computers) in which the camera module is operable in both portrait format ( FIG. 4 ) and landscape format ( FIG. 5 ). The host device can include an accelerometer that detects the orientation of the device relative to earth and allows the device to re-orient the display screen as the user changes the device&#39;s orientation. 
         [0032]    In some instances, when the smart phone  200  is in a vertical orientation for portrait format ( FIG. 4 ), the camera module  100  is used in an image capture mode, whereas when the smart phone is a horizontal orientation for landscape format ( FIG. 5 ), the camera module can be used in an iris recognition mode. Iris recognition can be advantageous to provide affirmative identification of a user and can, for example, be used to grant access of a host device to the user, and/or grant access to various applications or other software integrated into the host device (e.g., e-mail applications). 
         [0033]    As shown in  FIG. 4 , when the smart phone  200  or other host device is in the vertical orientation for portrait format, and the user activates operation of the camera module  100  (e.g., by pressing a button on the host device  200 ), an image  202  is acquired by the RGB sensor  103 A, read out by the read-out circuit  120 , and processed by the processing circuit  122 . The image  202  can be displayed, for example, on a display screen  204  of the host device  200 . 
         [0034]    A shown in  FIG. 5 , when the smart phone  200  or other host device is in the horizontal orientation for landscape format, the user can hold the smart phone  200  in front of his face such that one of the IR sensors  103 B is able to acquire an image  206  of the user&#39;s eyes when the user activates operation of the camera module  100  (e.g., by pressing a button on the host device  200 ). The acquired IR image data can be read out by the read-out circuit  120 , and processed by the processing circuit  122  in accordance with an iris recognition protocol. 
         [0035]    In some applications, iris recognition can be performed as follows. Upon imaging an iris, a 2D Gabor wavelet filters and maps the segments of the iris into phasors (vectors). These phasors include information on the orientation and spatial frequency and the position of these areas. This information is used to map the codes, which describe the iris patterns using phase information collected in the phasors. The phase is not affected by contrast, camera gain, or illumination levels. The phase characteristic of an iris can be described, for example, using 256 bytes of data using a polar coordinate system. The description of the iris also can include control bytes that are used to exclude eyelashes, reflection(s), and other unwanted data. To perform the recognition, two codes are compared. The difference between two codes (i.e. the Hamming Distance) is used as a test of statistical independence between the two codes. If the Hamming Distance indicates that less than one-third of the bytes in the codes are different, the code fails the test of statistical significance, indicating that the codes are from the same iris. Different techniques for iris algorithm can be used in other implementations. 
         [0036]    The IR image  202  captured by the IR sensor  103 A of the image sensor  102  in the camera module  100  also can be displayed, for example, on the display screen  204  of the host device  200 , which can help the user determine whether he properly positioned the camera module  100  in front of his face. 
         [0037]    Although some implementations of the module  100  may include only a single IR sensor  103 B, it can be advantageous in some cases to provide two IR sensors  103 B, located near the periphery of the image circle  105  on opposite sides of the RGB sensor  103 A (see  FIGS. 2, 4 and 5 ). Such an arrangement can make it easier for a user to use the host device  200  for iris recognition because the user need not remember whether to rotate the host device clockwise or counterclockwise in order to capture an image of his eyes. For example, if the user initially holds the host device  200  in its upright vertical orientation ( FIG. 4 ) and wants to use the host device for iris recognition, the user can rotate the host device by ninety degrees in either the clockwise or counterclockwise directions before activating the camera while it is positioned in front of his face. If the user rotates the host device by ninety degrees in the clockwise direction, then a first one of the IR sensors  103 B easily can be used to acquire an image of the user&#39;s eyes, whereas if the user rotates the host device by ninety degrees in the counterclockwise direction, then the second one of the IR sensors  103 B easily can be used to acquire an image of the user&#39;s eyes. 
         [0038]    As noted above, the host device  200  or the module  100  itself can include an IR eye-illumination source  130 . In some implementations, the eye illumination source  130  is operable to emit modulated IR radiation (e.g., for time-of-flight (TOF)-based configurations). In such implementations, an optical time-of-flight (TOF) sensor  132  (see  FIG. 3 ) or other image sensor operable to detect a phase shift of IR radiation emitted by the eye illumination source can be provided either as part of the module  100  or as a separate component in the host device  200 . The modulated eye illumination source can include one or more modulated light emitters such as light-emitting diodes (LEDs) or vertical-cavity surface-emitting lasers (VCSELs). 
         [0039]    In some instances, iris recognition (based on signals from the IR sensor  103 B) can be combined with other applications, such as eye tracking or gaze tracking. Eye tracking refers to the process of determining eye movement and/or gaze point and is widely used, for example, in psychology and neuroscience, medical diagnosis, marketing, product and/or user interface design, and human-computer interactions. In such implementations, the eye illumination source  130  is operable to emit homogenous IR illumination toward a subject&#39;s face (including the subject&#39;s eye), and can be modulated, for example, at a relatively high frequency (e.g., 10-100 MHz). A depth sensor such as a time-of-flight (TOF) sensor  132  detects optical signals indicative of distance to the subject&#39;s eye, demodulates the acquired signals and generates depth data. Thus, in such implementations, the TOF sensor  132  can provide depth sensing capability for eye tracking. In such implementations, operations of both the image sensor  102  and TOF sensor  132  should be synchronized with the eye illumination source  130  such that their integration timings are correlated to the timing of the eye illumination source. Further, the optical axes of the eye illumination source  130  and the image sensor  102  (which includes the IR pixels  103 D) should be positioned such that there is an angle between them of no less than about five degrees. Under such conditions, the pupil of the subject&#39;s eye appears as a black circle or ellipse in the image of the eye acquired by the IR sensor  103 B. It also can help reduce the impact of specular reflections from spectacles or contact lenses worn by the subject. 
         [0040]    The module  100 , as well as the illumination source  130  and depth sensor  132 , can be mounted, for example, on the same or different PCBs within a host device. 
         [0041]    Various modifications can be made within the spirit of this disclosure. Accordingly, other implementations are within the scope of the claims.