Abstract:
An improved imaging system includes a single solid state interlaced imager device such as a CCD camera chip, a displaceable mirror apparatus, and a controller for displacing the mirror apparatus in synchronism with the capture of video information by the imager device so as to obtain interlaced video information from multiple selected views. The mirror apparatus comprises a linearly displaceable shaft supporting two or more axially separated mirror surfaces and a motor-operated cam drive for reciprocatingly displacing the shaft to successively bring the mirrors into an aperture field of the imager device.

Description:
TECHNICAL FIELD  
       [0001]     The present invention relates to an imaging system adapted to capture video information pertaining to more than one image.  
       BACKGROUND OF THE INVENTION  
       [0002]     Imaging systems are finding increased application in non-traditional environments. In the automotive environment, for example, imaging systems are being proposed not only for the purpose of displaying various images to the driver, but also for data collection relevant to occupant detection, obstacle detection, pre-crash sensing, and so on. However, it has become apparent that utilizing multiple individual imaging systems is cost prohibitive in most applications, and is frequently unacceptable from a packaging standpoint. Accordingly what is needed is an improved imaging system that is easily packaged in an automotive environment, and that has the capability of capturing video information from multiple images.  
       SUMMARY OF THE INVENTION  
       [0003]     The present invention is directed to a multiple view imaging system including a single solid state interlaced imager device such as a CCD camera chip, a novel multiple view mirror apparatus, and a controller for operating the mirror apparatus in synchronism with the capture of video information by the imager device so as to obtain interlaced video information from multiple views. The mirror apparatus comprises a linearly displaceable shaft supporting two or more axially separated mirror surfaces and a motor-operated cam drive for reciprocatingly displacing the shaft to bring a selected mirror into an aperture field of the imager device. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0004]      FIG. 1A  is a diagram of an imaging system according to this invention, including an interlaced imaging device, a multiple view mirror apparatus, and a controller for positioning the mirror apparatus in synchronism with the capture of video information by the imaging device.  
         [0005]      FIG. 1B  schematically depicts a portion of the mirror apparatus of  FIG. 1  for a two-view mechanization of the invention.  
         [0006]      FIG. 1C  schematically depicts a portion of the mirror apparatus of  FIG. 1  for a four-view mechanization of the invention.  
         [0007]      FIG. 2  is a diagram of the mirror apparatus of  FIG. 1  for a two-view mechanization of the invention.  
         [0008]      FIG. 3 , Graphs A and B, depict a mirror control carried out by the controller of  FIG. 1 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0009]     While the imaging system of the present invention is described herein in the context of a motor vehicle, it will be appreciated that various non-automotive applications are also possible. Referring to  FIG. 1A , the reference numeral  10  generally designates a two-view imaging system according to this invention. The imaging system  10  includes a solid state interlaced imaging device  12  such as a CCD or CMOS camera chip, a mirror apparatus  14  positioned by an electric motor  16 , and a controller (μC)  18  responsive to an internal vertical sync signal of imaging device  12  for appropriately positioning the mirror apparatus  14 . In the illustrated embodiment, the controller  18  reciprocates the mirror apparatus  14  between two alternate imaging positions. The aperture field of the imaging device  12  is aligned (as indicated by the broken line  22 ) with a first mirror  20  when the apparatus  14  is in the illustrated imaging position, whereas the aperture field of the imaging device  12  is aligned with a second mirror  24  when the apparatus  14  is in the alternate imaging position. The mirrors  20  and  24  are affixed to a linearly displaceable shaft  26 , and the shaft  26  is mechanically coupled to a rotary cam mechanism  28  that is driven by the output shaft  30  of electric motor  16 . Thus, continuous energization of the motor  16  by controller  18  produces axial reciprocation of the shaft  26  and mirrors  20 ,  24  to alternately align the mirrors  20 ,  24  with the aperture field of the imaging device  12 . The imaging device  12  provides a video output on line  32  which may be supplied to a display or video processor, as the particular application requires, and the vertical sync signal is provided to the controller  18  via line  34 .  
         [0010]     The mirrors  20 ,  24  provide different angles of reflection for light incident to the imaging device  12  so that the imaging device  12  alternately produces video data from first and second scenes corresponding to the two different mirror angles.  FIG. 1B  depicts an exemplary mirror orientation, as seen by the imaging device  12 . In such depiction, the mirror  20  provides a left-facing view as indicated by the arrow A, and the mirror  24  provides a right-facing view as indicated by the arrow B. Of course, the mirror angles will be designed to suit a particular application, and may include vertical angulation as well as the depicted horizontal angulation. Also, the number of mirrors is not limited to two; in this regard,  FIG. 1C  depicts an exemplary mirror orientation for an embodiment including four mirrors  40 ,  42 ,  44 ,  46  that provide four different views to the imaging device  12 . In the four mirror implementation, reciprocal linear displacement of the shaft  26  successively brings four different views (A, B, C, D) into alignment with the aperture field of imaging device  12 .  
         [0011]      FIG. 2  depicts a mechanization of the mirror apparatus  14  for a two view application in which the mirrors  20 ,  24  are mutually deflected by 90 degrees, each mirror  20 ,  24  being deflected from the aperture field of imaging device  12  by 45 degrees. In such an embodiment, the imaging device  12  receives incident light from scenes to the right and left of its aperture field. Referring to  FIG. 2 , the mirrored shaft  26  is enclosed by a housing comprising first and second housing halves  50  and  52  and the domed cover  54 . The housing pieces  50 ,  52 ,  54  are fastened together as indicated, and coupled to the housing of electric motor  16  by a motor mount  56 . One end of the shaft  26  is supported by the domed portion of cover  54 , and other end of shaft  26  is coupled to the electric motor output shaft  30  by a connecting arm  58  and a crank arm  60  of cam mechanism  28 . The connecting arm  58  passes through an opening  56   a  in motor mount  56 , and the opening  56   a  is shaped to accommodate movement of the mirror  20 . The housing half  50  has an apertured side surface  50   a  designed to accommodate a circuit board (not shown), and the CCD imaging device  12  is mounted on the circuit board to receive incident light through the aperture  50   b.  The sides of housing halves  50 ,  52  are slotted as indicated by the reference numerals  50   c,    52   c  to form opposing apertures that are laterally aligned with the aperture  50   b.  Incident light enters the opposing apertures, and incident light entering one of the opposing apertures is reflected to the imaging device  12  via a mirror  20 ,  24  and the aperture  50   b.  When the shaft  26  is retracted as shown in  FIG. 2 , light entering the housing aperture in the foreground of the drawing is reflected to the imaging device  12  by the mirror  24 , and when the shaft is extended, light entering the housing aperture in the background of the drawing is reflected to the imaging device  12  by the mirror  20 .  
         [0012]     Obviously, various mechanizations other than described above are possible. But in any event, the controller  18  coordinates mirror movement with the data capture of the imager device  12  so that at least two images are interlaced in a single video frame. Thus, whereas a traditional video frame contains interlaced even-numbered and odd-numbered rows of pixels that contain substantially similar information and are alternately integrated at a fixed periodicity and then read out to a capture device, a video frame according to the present invention contains interlaced even-numbered and odd-numbered rows of pixels in which the even-numbered rows contain information from one view and the odd-numbered rows contain information from an entirely different view.  
         [0013]     A typical implementation is depicted in Graphs A and B of  FIG. 3 , where Graph A depicts a vertical sync pulsetrain (V) and Graph B depicts the movement of the mirrored shaft  26 , both as a function of time. The vertical sync pulses initiate the alternate row pixel integration process every 16.66 ms for an information capture rate of 30 frames per second, and the obtained video data is read out to the capture device in a field readout period between sync pulses as indicated. As indicated in Graph B, the shaft movement is continuous and in synchronism with the pixel integration rate, with the mirrors  20 ,  24  being alternately in position during the field integration periods, and out of position during the field readout periods. For the mechanization of  FIG. 2  for example, mirror  20  is in position (POS1) relative to the respective housing apertures during odd field pixel integration, and the mirror  24  is in position (POS2) during even field pixel integration. In this way, two (or more) different views can be captured in a single video frame with no sacrifice with respect to the frame rate of the interlaced imager  12 , regardless of the angular separation of the views.  
         [0014]     In summary, the present invention provides an imaging system that is capable of capturing video information pertaining to two or more different views with a single interlaced imaging device without degrading its frame rate. While described in reference to the illustrated embodiments, it is anticipated that various modifications in addition to those mentioned above will occur to those skilled in the art. For example, the views may be entirely different as shown, or may be segments of a single view (in which case subsequent processing may be used to combine the two views into a single wide angle view). Accordingly, it will be understood that imaging systems including these and other modifications may fall within the scope of this invention, which is defined by the appended claims.