Abstract:
A night vision attachment for a SmartPhone by which the camera of the SmartPhone is enabled to view or take digital photos of objects under very low light ambient light levels. The night vision attachment comprises a housing for receiving and locating components of the attachment and has portions adapted to mate with a wall of the camera through which the phone camera lens images object space. Located in the attachment housing are an image detector sensitive to infrared (IR), an objective lens for forming images on the image detector whereby the image detector operates to generate image output signals representative of detected images, a display arranged to receive the image output signals from the image detector and to generate a visible image; and an eyepiece for viewing images formed on the display and permitting the camera of the phone to focus on the display images when the attachment is mated to a phone. IR LEDs are used to illuminate scenes. Snap fit connectors releasably hold the attachment in mating contact with the phone so that the camera of the phone is optically aligned with the axis of the eyepiece to permit the camera to view images on the display via the eyepiece.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention generally relates to night vision apparatus and more specifically to an attachment for a cellular or Smartphone for converting its camera for low light level digital imaging. 
       BACKGROUND OF THE INVENTION 
       [0002]    Smartphones are handheld electronic devices built on a mobile operating system to provide more advanced computing capability and connectivity than a conventional cellular telephone. The first smartphones combined the functions of a personal digital assistant (FDA) with a mobile phone. Later models added the functionality of portable media players, low-end compact digital cameras, pocket video cameras, and GPS navigation units to form one multi-use device. Many modern Smartphones also include high-resolution touch screens and web browsers that can display standard web pages as well as mobile-optimized sites. High-speed data access is provided by Wi-Fi and mobile broadband. In recent years, the rapid development of mobile app markets and of mobile commerce have been drivers of Smartphone adoption. 
         [0003]    The mobile operating systems (OS) used by modern smartphones include Google&#39;s Android, Apple&#39;s iOS, Nokia&#39;s Symbian, RIM&#39;s BlackBerry OS, Samsung&#39;s Bada, Microsoft&#39;s Windows Phone, Hewlett-Packard&#39;s webOS, and embedded Linux distributions such as Maemo and MeeGo. Such operating systems can be installed on many different phone models, and typically each device can receive multiple OS software updates over its lifetime. 
         [0004]    The past several decades has also seen the development of steadily improving lens designs that have evolved to the point where they have become suitable for integration into cellular phones and, more recently, Smartphones. Indeed, the bulk of digital images created today are taken with cellular phones equipped with digital cameras, thus making point and shoot cameras an endangered species. Even so, such phones do have limitations. For example, it is difficult to snap good close-ups, distant shots, or night vision shots or videos where lighting is so poor the camera is unable to cope. 
         [0005]    While attachments have been provided to improve close-up and distant shots, none exists for permitting a user to take night vision shots or videos or display screen images visible to a user under poor ambient lighting. 
         [0006]    Accordingly, it is a primary object of the present invention to provide an attachment for a Smartphone that will enable a user to take night vision digital photos and videos under poor lighting conditions. 
         [0007]    It is another object of the present invention to provide an attachment for a Smartphone that will enable a user to visualize his surroundings under low light level conditions. 
         [0008]    Other objects of the invention will in part be obvious and will in part appear hereinafter when the following detailed description is read in connection with the accompanying drawings. 
       SUMMARY OF THE INVENTION 
       [0009]    A night vision attachment for a SmartPhone by which the camera of the SmartPhone is enabled to view or take digital photos and or videos of objects under very low light ambient light levels. 
         [0010]    The night vision attachment is adapted to be used with SmartPhones having cameras and comprises a housing for receiving and locating components of the attachment. The housing has portions adapted to mate with a wall of the camera through which the phone camera lens images object space. 
         [0011]    Located in the attachment housing are:
       an image detector located in the housing along an optical path;   an objective lens located along the optical path for forming images on the image detector whereby the image detector operates to generate image output signals representative of detected images;   a display arranged to receive the image output signals from the image detector and to generate a visible image; and   an eyepiece positioned in said housing for viewing images formed on said display and permitting the camera of the phone to focus on said display images when said attachment is mated to a phone.       
 
         [0016]    Snap fit connectors depend from the housing for snapping around the camera releasably hold the attachment in mating contact with the phone so that the camera of the phone is optically aligned with the axis of the eyepiece to permit the camera to view images on said display via the eyepiece. 
         [0017]    In an aspect of the invention, the camera and illumination system of the attachment comprises a solid state imager having an operating mode having substantial sensitivity to infrared radiation within its field of view and adapted to generate an image output signal representative of the subject matter that it observes and a radiation source to generate infrared radiation and to direct such radiation into the field of view of the solid state imager. 
         [0018]    In another aspect of the invention, a display is arranged to receive the image output signal from the solid state imager and to generate an image visible to the SmartPhone camera via the eyepiece. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    The structure and operation of the night vision modular system of the present invention, together with other objects and advantages thereof, may best be understood by reading the following detailed description in connection with the drawings in which unique reference numerals have been used throughout for each part and wherein: 
           [0020]      FIG. 1A  is an exploded diagrammatic perspective view of a SmartPhone and an inventive attachment separated from the SmartPhone; 
           [0021]      FIG. 1B  is a diagrammatic perspective view of the SmartPhone and attachment of  FIG. 1A  showing the attachment mated with the SmartPhone to convert it for use in taking digital photos and or video or allowing a user to visualize her surroundings under low ambient light level conditions; 
           [0022]      FIG. 2A  is a diagrammatic perspective of the inventive SmartPhone attachment with parts broken away to visualize aspects of its optical system; 
           [0023]      FIG. 2B  is an enlarged diagrammatic perspective of a portion of the inventive attachment shown in  FIG. 2A ; 
           [0024]      FIG. 3A  is a diagrammatic perspective of the inventive SmartPhone attachment with parts broken away to visualize aspects of its optical and illumination system; 
           [0025]      FIG. 3B  is an enlarged diagrammatic perspective of a portion of the inventive attachment shown in  FIG. 3A ; 
           [0026]      FIG. 4  is a schematic block diagram view of the optical and image-generating components of the inventive SmartPhone attachment shown in  FIGS. 1A  thru  3 B and illustrate the camera and display module used in conjunction with an auxiliary optical module; and 
           [0027]      FIG. 5  is a block diagram showing the generation and display of image signals from components of the inventive modules; and 
           [0028]      FIG. 6  is a graph showing a typical spectral response of the solid state imager and a typical spectra of the emissions from the light emitting diodes shown in  FIG. 4  and elsewhere. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0029]    The present invention is an attachment for a SmartPhone, or the like, by which the camera of the SmartPhone can be used to take digital photos and or videos, or its user can visualize his surroundings, under very low ambient light levels. Under low light level conditions beneath which the SmartPhone cannot “see” its surroundings, the attachment operates to provide images to the SmartPhone&#39;s camera at light levels that the SmartPhone camera can see and which, in turn, enables the SmartPhone camera to operate normally as though the light levels were higher. 
         [0030]    To understand how the inventive attachment achieves its purpose, reference is now made to  FIG. 1A  which is a diagrammatic view showing in perspective a SmartPhone  10  separated from an inventive attachment  22 . 
         [0031]    SmartPhone  10  may be any of a number of those marketed in large volumes such as the Apple i-phone series or Samsung Galaxy series, or the like. It is well-known that such phones have optical systems that may acquire images of their surroundings and present them for viewing on high resolution touch and display screens such as that designated generally at  12 . Such optical systems, designated generally at  15 , typically face a scene to be visualized and reside on the side opposite their display screen  12 . Other controls such as those designated generally at  14 ,  16 ,  18  and  20  are utilized in a well-known manner to select and control other features including, but not limited to, gaining access to the internet, interacting with resident apps, listening to audio files, looking at video files, or the like. 
         [0032]    Referring now to  FIG. 18 , the low light level attachment  22  can be seen to have housing  23  that is provided with a shape that is designed to mate in complementary fashion with the back side of the SmartPhone  10  where it is held in place against the back side via three flexible fingers  24 ,  26  and  28 . The flexible fingers  24 ,  26  and  28  are cantilevered from the attachment  22  via a camming section  29  and flexible cantilevered section  31  that bends under the influence of the camming action of camming section  29  pressed against the edges of the backside of SmartPhone  10 . Housing  23  otherwise is configured in a well-known manner to receive and position various components of attachment  22  to be described in more detail hereinafter. 
         [0033]    As best shown in  FIG. 1A , attachment  22  is provided with an aperture  30  that is positioned so that it is automatically aligned with the optical system of SmartPhone  10  when attachment  22  is mated with the SmartPhone  10  as shown in  FIG. 1B . Aperture  30  permits the optical system of SmartPhone  10  to view an image formed on a display (See display  166  in  FIG. 2B ) that forms part of attachment  22 &#39;s optical and illumination system to be described more fully later. As depicted in  FIG. 1B , attachment  22  operates under very low ambient lighting conditions to provide images on screen  12 , such at that designated at  32 , that SmartPhone  10  would otherwise not be able to provide. 
         [0034]    Attachment  22  is powered either by the internal battery of SmartPhone  10  via a well-known connector  40  into which SmartPhone  10  plugs or by a separate power pack that plugs into the free end of connector  40 , i.e. the end that is not occupied by SmartPhone  10 . 
         [0035]    Referring now to  FIGS. 2A through 3B , the manner by which attachment  22  forms images on display  166  under low light level conditions will now be taken up. Generally, it involves the use of a solid state imager  160  sensitive to infrared radiation, a source for generating infrared radiation (a series of encapsulated IR LEDs  154 ) within the spectral response range of the solid state imager  160  and directing this radiation into the field of view of the imager  160 , and an image generator  166  that receives the output from the imager  160  and generates a visible image representative of the output of the image at a position visible to SmartPhone  10 &#39;s camera as seen through aperture  30 . Thus, in contrast to passive military night vision apparatus, the night vision attachment of the present invention is an “active” apparatus which generates infrared radiation used to form the image. Since the scene being viewed is being “illuminated” (in the infrared) by the attachment itself, the attachment of the present invention can use a solid state imager much less sensitive, and much less costly, than the image intensifier tube arrangements typically used in military night vision apparatus. The preferred form of solid state imager for use in the present invention is a complementary metal oxide semiconductors (CMOS) device, although other solid state imagers may also be used. 
         [0036]    As discussed in more detail below with regard to  FIG. 6 , CMOS imagers are usually sensitive to infrared radiation only in the range of about 700 to 1000 (or in some case at wavelengths as long as 1050-1075) nm. CMOS sensors are, of course, also generally sensitive to visible radiation of 400 to 700 nm, and in the present invention, there is no particular reason to exclude visible light from the imager  160 , i.e., the imager  160  can be allowed to form an image using both the infrared radiation reflected from the scene viewed and any available ambient visible light. If a CMOS sensor is used in the present invention, the infrared radiation source is chosen to generate infrared radiation within the range of about 700 to 1000 nm to which such imagers are particularly sensitive. Also, it is desireable to illuminate the scene at wavelengths that will not be visible to the user of the device or an individual in the vicinity of the device. Fortunately, inexpensive infrared radiation emitting diodes operating within this range are readily available commercially. Operating in the 700 to 1000 nm range also has the advantage that the images generated using such near infrared radiation are much more similar to visible images than images formed using far infrared radiation with wavelengths of 2000 nm or more, and hence are easier for inexperienced users to interpret. 
         [0037]    As best seen in  FIGS. 2A  and B, attachment  22  has an objective lens  158  arranged along optical axis. Objective lens  158  may be an aspherized singlet to bring it to an acceptable state of correction or may be of more complex design including more than one element any or all of which may include aspheric surfaces (See  FIG. 4 ). Objective lens  158  is preferably fixed focus set to a hyperfocal distance of may be focused at or near infinity. As may be noted, the optical axis of objective lens  158  is offset with respect to the optical axis of display  166  which in turn is in axial alignment with the taking lens of SmartPhone  10 . As such there is some degree of parallax between what the SmartPhone  10  would see without attachment  22  and what it sees with the attachment in place but this is negligible and is not noticeable to a user since the user observes images formed by the attachment on screen  12 . 
         [0038]    Surrounding the optical axis of objective lens  158  are a plurality of IR LEDs  154  which may all be turned on at once to optimize the distance at which images may be formed. 
         [0039]    The camera and illumination system of attachment  22 , as best seen in  FIGS. 4 and 5 , comprises the objective taking lens  158 , preferably a centrally located micro video lens, surrounded by the circular pattern of IR LEDs  154 . Behind the micro video lens  158  is located a CMOS image sensor  160  (See  FIGS. 3B and 3 ).
   The LEDs  154  used are preferably of two different types, one having a narrow field of emission and the other having a substantially wider field of emission, with the two types alternating around the circular pattern. It has been found that this arrangement of narrow angle and wide angle diodes provides optimal illumination of the entire field of view of the image sensor  160 , the narrow angle diodes illuminating more distant objects while the wide angle diodes the closer objects. However, it will be recognized that one or the other can be used or used in different geometries and quantities consistent with the need to minimize the power consumption of attachment  22  and hence the drain on batteries.   
 
         [0041]    A red filter may be mounted forward of the LEDs  154  to pass infrared and visible radiation having wavelengths greater than about 650 nm. 
         [0042]    The other optical and image-forming components are as follows (Refer to  FIG. 4 ): 
         [0043]    (a) the micro video lens  158  which extends through a central aperture along the optical axis, gathers infrared and visible radiation, and images this radiation on to 
         [0044]    (b) the CMOS sensor  160  mounted along the optical axis in the camera and illumination module  14 ; 
         [0045]    (c) a display elements  25  comprising a back-lighting unit  162  having the form of a green light-emitting diode (see below with reference to  FIG. 6 ) combined with a scattering reflector  174 . In  FIG. 2B , the scattering reflector  174  and diffuser  164  have been omitted for ease in seeing LCD display  166 ; 
         [0046]    (d) a diffuser  164  disposed adjacent the back-lighting unit  162  to diffuse light emitted from the back-lighting unit; 
         [0047]    (e) a liquid crystal display  166  disposed adjacent the diffuse  64  so as to be backlit by light passing therethrough;
   (f) an auxiliary optics module comprising an eyepiece assembly  170  arranged to form provide an image of the display  166  at a distance that can be focused on by the camera lens of SmartPhone  10 . Those skilled in the art of optical design will readily be able to adjust the properties of eyepiece  170  to accommodate the SmartPhone&#39;s camera lens.   
 
         [0049]    The mode of operation of the optical and imaging components  158 - 170  of the invention will now be explained with reference to  FIGS. 4 and 5 . As shown schematically in  FIG. 4 , the infrared LEDs  154  emit infrared radiation that passes through a filter (not shown), is reflected from objects in front of the user, passes back through a centrally located aperture, and is imaged by the two-element micro video lens  158  on the CMOS sensor  160 . As shown in  FIG. 5 , the sensor  160  generates a standard RS170 video output signal that is fed to a monochrome video display driver  163 . The output from driver  163  is fed to the liquid crystal display  166 . 
         [0050]    Returning to  FIG. 4 , it will be seen that the back-lighting unit  162  comprises a green LED  172  lying within a frusto-conical cavity in a scattering reflector  174 , the diffuser  164  lying across the wide end of the frusto-conical cavity. A green diode is chosen because this is the color to which the human eye is most sensitive, and hence minimizes light output and power consumption for an image of any desired intensity. Also, it is reminiscent of the color of phosphors used in some military night vision systems and provides a desirable user comparison to traditional military night vision systems. The combination of the scattering reflector  174  and the diffuser  164  provides a substantially uniform distribution of green light across the diffuser  164  and hence substantially uniform back-lighting of the display  166  disposed adjacent the diffuser  164 . Green light passing through the display  166  is imaged by the two-element eyepiece assembly  170  of the auxiliary optics module to form an image visible to the SmartPhone camera. 
         [0051]    The arrangement of optical and imaging components shown in  FIGS. 4 and 5 , in which the sensor  160  and the display  166  are substantially aligned along a common axis, provides an extremely compact and convenient form factor. The arrangement is also designed to avoid two potential problems. As shown in  FIG. 6 , the infrared diodes  154  emit at around 850 nm, the green diode  172  emits around 575 nm, and the sensor  160  has substantial sensitivity over the range of about 475 to about 1075 nm. Accordingly, it is necessary to arrange the optical system so that no light from green diode  172  can reach the sensor  160 , since the sensor would be affected by the green light and the desired infrared image would be degraded. The arrangement of the green diode  172  within the frusto-conical cavity of the reflector  174  and the mounting of the sensor  160  immediately adjacent the “back” surface of the reflector  174  (i.e., the surface facing away from the diffuser  164 ) prevent light from the green diode  172  reaching the sensor  160 . Also, for reasons already noted, it is undesirable for a night vision system to emit any visible light, and proper filtering assures that any light from the green diode  172 , which may be reflected forwardly (i.e., away from the user), for example by reflection from the display  166 , will not emerge from this module. 
         [0052]    The preferred attachment of the present invention shown in the accompanying drawings is simple, compact and can readily be manufactured using inexpensive, commercially available components. For example, the monochrome display driver can be a Motorola MCVVQ111 VirtuoVue driver, while the display  166  can be a Cyberdisplay  320  display, available from Kopin Corporation of Taunton Mass., with a 320×240 pixel output. The sensor  160  can be an OmniVision OV5116N CMOS sensor available from OmniVision Technologies, Inc., of Sunnyvale Calif., while the infrared diodes  154  can be Model RT-7507ET from Rodan (Taiwan) Ltd., and the green diode  174  can be a Kingbright Model AA3528 surface mount LED lamp. Using such components, bright images within the range from about 30 to 100 feet can be readily seen. 
         [0053]    It will readily be apparent to those skilled in the art that numerous changes and modifications can be made to the preferred embodiments of the invention described above without departing from the scope of the invention. For example, the CMOS sensor  160  could be replaced by another type of solid state imager, for example a charged coupled device (CCD). A color camera that also has extended infrared sensitivity could be used in conjunction with a color display to provide a color rendition of the visible scene. Higher resolution (high-definition) imager and displays could be used with associated higher costs. Therefore, it is intended that the embodiments described herein be considered as illustrative and not be construed in a limiting sense. From the foregoing, it will be seen that the present invention provides a night vision apparatus that is adaptable, inexpensive, compact, robust and well suited for use by the general public, and which does not emit visible radiation permitting observations that can be made at night without notice by or disturbing animals. 
         [0054]    If there is sufficient light, there may be no need for the illumination module to be activated to supply additional illumination to the scene. If a visible light detector is incorporated into the illumination system or if the camera is used (with the illumination system turned off) to measure the amount of ambient light, a determination can he made as to whether additional illumination is required and the output of the illumination source adjusted to add additional illumination. If additional illumination is required to view the scene, either infrared light and/or visible light can be activated. The advantage of using infrared light is that it will not be observed by individuals or animals that are in the immediate area of the illumination system. 
         [0055]    Other embodiments of the invention will be apparent from its teachings, and such variants are intended to be within the scope of the appended claims.