Abstract:
A driver vision enhancing system having a variable field of regard and a method of controlling the field of regard of a driver vision enhancing system. The system includes a housing, a movable sensor assembly located within the housing, a radiation detector connected to one end of the sensor assembly, and an actuator connected to the housing and able to contact the sensor assembly to move the sensor assembly in the housing and thereby move the radiation detector. The method includes moving a radiation detector as part of a driver vision enhancing system in a vertical direction within an image plane of the driver vision enhancing system.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a method of and apparatus for adjusting the field of regard of driver&#39;s vision enhancing systems. 
   BACKGROUND 
   It is known in the art to use night vision systems to allow the driving of vehicles at night and under adverse weather conditions. One such night vision system, known as a Driver&#39;s Vision Enhancer (DVE) is described in U.S. Pat. No. 6,521,892 to Emanuel et al. The Emanuel DVE consists of a forward-looking thermal imager, also known as a Sensor Module (SM), for acquiring thermal radiation from a viewed scene and a Display and Control Module for displaying a visible image of the scene to the driver. 
   The portion of the scene called the Field of View can be acquired at any time and is expressed in elevation and azimuth angles. Such DVE systems are also equipped with mechanisms allowing the user to rotate the optical axis of the SM in elevation and azimuth to allow acquisition of the scene beyond the limits of the Field of View. The total scene area viewable by the DVE system is called the Field of Regard (FOR). The FOR includes the FOV and is frequently larger than the FOV, i.e., a non-movable DVE has a fixed FOR and FOV covering the same azimuth and elevation. For example, U.S. Pat. No. 6,563,102 to Wrobel et al. describes a FOR mechanism useable with the Emanuel DVE system described above. 
   Existing techniques for rotating the optical axis of the SM include rotating the SM itself in both azimuth and elevation, e.g., as used in the Wrobel patent, and rotating the associated folding mirror for vertical FOR and rotating the SM itself for the horizontal FOR, e.g., as used in DVE systems having periscopic optics having a vertical optical axis. 
   Several techniques can be used to rotate the optical axis of the Sensor Module. The one described in the aforementioned patent uses the rotation of the Sensor Module itself in both azimuth and elevation. DVE systems using periscopic optics (vertical optical axis) use the rotation of an associated folding mirror to provide vertical FOR and use the rotation of the SM itself for the horizontal FOR. 
   In order to utilize a mirror in the periscopic DVE systems, an entrance window is positioned in front of the mirror to prevent dust and contaminants from reaching the mirror. A lens assembly positioned to receive light from the mirror directs an image to a radiation detector for processing and ultimately display to a user. In operation, light from a viewed scene passes through the entrance window, reflects off the mirror, and passes through the lens assembly to the radiation detector. A reduction in light received from a viewed scene occurs as the light passes through the multiple components of the folding mirror mechanism. 
   There is a need in the art for an alternate FOR mechanism and associated SM packaging, which is applicable to forward looking DVE systems. Further, there is a need in the art for such a system that is improved in terms of simplicity, cost, and performance. 
   SUMMARY 
   It is therefore an object of the present invention to provide an improved FOR mechanism. 
   Another object of the present invention is to provide such an improved FOR mechanism having reduced cost and improved performance. 
   The present invention provides a driver vision enhancing system having a variable field of view. The system includes a housing and a movable sensor assembly located within the housing. The sensor assembly includes a radiation detector connected to one end of the assembly. An actuator connected to the housing is able to contact the sensor assembly and move the sensor assembly in the housing and thereby move the connected radiation detector. 
   A method aspect includes moving a radiation detector as part of a driver&#39;s vision enhancing system in a vertical direction within an image plane of the optics of the driver&#39;s vision enhancing system. 
   There are numerous advantages to the below-described FOR mechanism, a brief summary of the advantages includes:
         small part count;   compact and high performance;   low cost;   reliable; and   simple electronics packaging.       

   As seen in  FIGS. 2 and 3 , the mechanism embodiment according to the present invention includes fewer parts in comparison to the above-described folding mirror-based system. One of the more complex parts, the sensor tube, is also used to hold the electronic boards and serves as a heat sink for the infrared detector. 
   Because the system does not include any mirror and entrance window, the system can be made very small in comparison with folding mirror-based systems. Additionally, the resulting optical transmission of the optics means more energy on the detector for higher performance. That is, fewer optical components impact the light passing through the system, thereby allowing more received light to reach the detector. 
   Lower cost is possible because the sliding mechanism involves only cylindrical shapes easily machined with high accuracy. 
   Reliability is increased because the moving parts are fully enclosed in the main housing and cannot be subjected to contamination from the environment or subjected to accidental shock or abuse. 
   Simple packaging is available because the infrared detector is mounted directly in the sensor engine board without the need for a separate detector board, connector, or flexible interconnecting circuit for lower cost and higher reliability. 
   Still other advantages of the present invention will become readily apparent to those skilled in the art from the following detailed description, wherein the preferred embodiments of the invention are shown and described, simply by way of illustration of the best mode contemplated of carrying out the invention. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the invention. 

   
     DESCRIPTION OF THE DRAWINGS 
     The present invention is illustrated by way of example, and not by limitation, in the figures of the accompanying drawings, wherein elements having the same reference numeral designations represent like elements throughout and wherein: 
       FIG. 1  is a perspective view of an example sensor module according to an embodiment of the present invention; 
       FIG. 2  is an exploded part view of the sensor module of  FIG. 1 ; 
       FIG. 3  is an exploded part view of the sensor module of  FIG. 1  from a lower elevation; 
       FIG. 4  is a perspective view from a lower elevation of the sensor module of  FIG. 1 ; 
       FIG. 5  is an other side perspective view of the sensor module of  FIG. 1 ; and 
       FIG. 6  is an exploded part view of an actuator of the sensor module of  FIG. 1 . 
   

   DETAILED DESCRIPTION 
   In contrast with the above-described approaches, the mechanism of the present invention slides the infrared detector located in the SM vertically, in the focal plane of the forward-looking optics to provide elevation FOR. 
     FIG. 1  is a perspective view of an example embodiment of the present invention. Sensor module  10  includes a main housing  12  and a lens assembly  14 , e.g., a forward-looking optics module, attached to the main housing. 
     FIG. 2  is an exploded part view of the sensor module  10  of  FIG. 1  whereby lens assembly  14  has been removed from sensor module  10 . Lens assembly  14  includes an aperture  16  in one face for receiving and providing electromagnetic waves, e.g., infrared waves, to the interior of sensor module  10  by way of a lens system  17  installed in lens assembly  14 . Lens assembly  14  is connected to main housing  12  via four attaching devices  18 , e.g., bolts, screws, or other form of attaching mechanism. 
   Similarly, a sensor tube assembly  20  has been removed from within the main housing  12  for better illustration of the features of the sensor tube assembly and bottom cover  22  has been removed from housing  12 . In the assembled configuration as depicted in  FIG. 1 , bottom cover  22  is affixed, e.g., screwed or bolted, to the bottom of housing  12  to close and seal the housing. Sensor tube assembly  20  moves in a vertical direction A along a longitudinal axis B of main housing  12  within a vertical cylindrical bore of the housing. It will be understood by persons skilled in the art that sensor tube assembly  20  may be a different shape, e.g., dovetail, rectangular, hexagonal, octagonal, poly-sided shapes, fitting within housing  12  and allowing movement of assembly  20  within housing  12 . Further, it will be understood that housing  12  may be a different shape in order to fit a particular embodiment. 
   A spring  24 , e.g., a compression spring, is located on an upper portion  25  of bottom cover  22  and applies force to a bottom  27  (shown more clearly with reference to  FIG. 3 ) of sensor tube assembly  20  for biasing the sensor tube assembly direction of movement and initial position within main housing  12  of sensor module  10 . More specifically, spring  24  is compressed and inserted between bottom cover  22  and sensor tube assembly  20  to apply upward force on sensor tube assembly toward an actuator  28  (described in detail below with reference to  FIGS. 4 and 6 ). Actuator  28  limits the upward movement of the sensor tube assembly  20  because the actuator is in contact with a sensor tube assembly flange  29 . Bottom  27  of sensor tube assembly  20  extends beyond the outer perimeter of sensor tube assembly  20  thereby forming a flange  29  along an outer periphery of the bottom of the assembly. 
   An electromagnetic radiation detector  26 , e.g., an infra-red radiation detector, is mounted at an upper end of sensor tube assembly  20 . A radiation sensitive area of detector  26 , when positioned inside main housing  12 , is aligned with the optical axis of lens system  17  of lens assembly  14 . Lens assembly  14 , and more specifically lens system  17  optics, creates an image larger than the radiation sensitive area of detector  26 . 
   Main housing  12  includes a knob  30  external to, and positioned toward the base of, the main housing and connected to a cam  31  via a shaft  32  (described below in conjunction with  FIGS. 4 and 6 ) for adjusting the position of sensor tube assembly  20 , and ultimately detector  26 , within sensor module  10 . Cam  31  is positioned internal to main housing  12  and adjacent to an upper portion of flange  29 . Cam  31  rotates in response to rotation of knob  30  due to connection with shaft  32 . It is to be understood that in alternate embodiments, cam  31  may be movable in a different manner than rotation, e.g., vertical movement. Further, cam  31  in a particular embodiment is a movable device having an offset axis of rotation, e.g., a device having a camming action. It is to be further understood that in alternate embodiments, cam  31  may be replaced by alternate mechanisms including but not limited to a lever or rack and pinion. 
   In operation, manipulation of knob  30 , e.g., clockwise or counter-clockwise rotation, causes actuator  28  to exert force against the upper portion of flange  29 , and thereby against the biasing force of spring  24 , to raise and lower sensor tube assembly  20 . Raising and lowering assembly  20  raises and lowers infrared detector  26  within the image plane of aperture  16  of lens assembly  14 . Consequently, the radiation sensitive area of infrared detector  26  is exposed to different segments of the overall image formed by the image plane of aperture  16  of lens assembly  14 . Therefore, manipulation of knob  30  shifts the field of view of sensor module  10  vertically. It will be understood by persons of skill in the art that the field of view of sensor module  10  may also be shifted horizontally or at a predetermined angle through application of the herein described technique. 
   The mechanism of the present invention slides the infrared detector located in the sensor module  10  vertically, in the focal plane of the forward-looking optics to provide elevation FOR. 
   Sensor tube assembly  20  is now described in more detail with reference to  FIG. 3 . Infrared detector  26 , e.g., a microbolometer, and two electronic Circuit Card Assemblies (CCA), i.e., a sensor engine CCA  35  and a power supply CCA  36 , each attached to sensor tube assembly  20 . Sensor engine CCA  35  provides processing capability necessary for generating an image from the infrared detector  26 . Sensor engine CCA  35  includes the microbolometer detector and electronics necessary for creation of a video signal as is known to persons skilled in the art. Power supply CCA  36  provides power from an external power source (not shown) to sensor engine  35  connected thereto and infrared detector  26 . Power supply CCA  36  includes a microcontroller for monitoring various controls on a display and control module (not shown) and adjusts various operating parameters of the sensor module  10 . The display and control module displays the video signal obtained by the infrared detector  26  and includes controls manipulable by a user for adjusting the gain, level and brightness of the display, switching of polarity (black hot/white hot), and selection of the video source (internal/external). Advantageously, mounting the sensor engine CCA  35  and power supply CCA  36  to assembly  20  facilitates rapid removal and replacement of damaged/defective components. Further, mounting CCAs  35 ,  36  within the cylindrical bore of the main housing  12  requires less space outside the sensor module  10  for the board and associated components. 
   With respect to  FIG. 3 , a pin  37  (also depicted in  FIG. 4 ), e.g., a dowel pin or other projection, mounted in main housing  12  interfits with a slotted portion  38  of flange  29  of sensor tube assembly  20  and thereby prohibits rotation of the sensor tube assembly within the main housing. As sensor tube assembly  20  is slid into main housing  12 , pin  37  projects into slotted portion  38  and cam  31  of actuator  28  is adjacent to upper portion  39  of flange  29 . In one embodiment, actuator  28  is in constant contact with upper portion  39  of flange  29  while sensor tube assembly  20  is installed in main housing  12 . In this embodiment, spring  24  exerts a constant force to the bottom  27  of assembly  20  pushing flange  29  toward, and in contact with cam  31  of actuator  28 . 
   As depicted in  FIG. 4 , rotation of knob  30  causes rotation of actuator  28 , and more specifically cam  31 , in contact with flange  29  of the sensor tube assembly  20 . Rotation of cam  31  applies a vertical force in direction C to flange  29  thereby compressing spring  24  as shown. In an alternate embodiment, spring  24  is located above flange  29  and exerts force on the upper surface of the flange and actuator  28  is located below flange  29  and in contact with the lower surface of the flange. In operation, actuator  28  exerts a vertical force opposite to direction C to flange  29  thereby compressing spring  24  and vertically moving sensor tube assembly  20 . 
   As described above, actuator  28  enables the operator to move the sensor tube assembly  20  inside the main housing  12  thereby moving the infrared detector  26  vertically in the image plane so as to provide the required elevation FOR. Generally, in military Combat Vehicles, the sensor module  10  is interfaced to the vehicle through a mounting block (not shown). In such systems, the azimuth FOR is realized by rotating the sensor module  10  within the mounting block. 
   In an alternative embodiment, actuator  28  moves sensor assembly  20  without directly contacting the assembly. For example, actuator  28  may be a pneumatic, fluid pressure, electromagnetic or other non-contact system for moving assembly  20  without necessitating direct contact of actuator  28  with the assembly. 
     FIG. 6  is a lower side perspective view depicting an embodiment of actuator  28  of the present invention separate from main housing  12 . As described above, actuator  28  includes knob  30  connected to cam  31  via shaft  32 . In operation, movement of knob  30  causes rotation of shaft  32  and concurrent rotation of cam  31 . In the particular embodiment depicted in  FIG. 6 , actuator  28  further includes a gear  33 , e.g., a segment gear, attached to shaft  32  and a plunger  34 , e.g., a spring plunger, connected to main housing  12 . Plunger  34  is biased toward gear  33  and the top of plunger  34  interacts with the teeth of gear  33  to prevent counter-rotation of shaft  32  and cam  31  in reaction to spring  24  exerting force against assembly  20 . 
   It will be readily seen by one of ordinary skill in the art that the present invention fulfills all of the objects set forth above. After reading the foregoing specification, one of ordinary skill will be able to affect various changes, substitutions of equivalents and various other aspects of the invention as broadly disclosed herein. It is therefore intended that the protection granted hereon be limited only by the definition contained in the appended claims and equivalents thereof.