Patent Publication Number: US-7721481-B2

Title: Head up display for firearms

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   The present application is a continuation of Ser. No. 11/424,982 filed Jun. 19, 2006, now U.S. Pat. 7,454,860, which is a division of U.S. Ser. No. 10/662,213 filed Sep. 12, 2003, entitled Diffractive Head Up Display for Firearms now U.S. Pat. No. 7,069,685 each of which is expressly incorporated by reference. 

   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not Applicable. 
   REFERENCE TO A “SEQUENCE LISTING” 
   Not Applicable. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to head up displays, and more particularly, to a head up display for firearms, wherein a plurality of images can be selectively presented to a viewer. 
   2. Description of Related Art 
   There are several types of sights used with small arms, such as rifles, shotguns, handguns, bows and other similar hand held weapons including sights which incorporate holographic images of various one, two and three dimensional reticle patterns. Prior devices incorporating holograms are shown in U.S. Pat. Nos. 5,483,362; 4,643,515; 5,151,800; 5,815,936; and 6,490,060. 
   However, a need exists for a head up display for firearms which can provide a variable or a variety of images in response to user input. The need also exists for a compact lightweight head up display system that can be cooperatively engaged with firearms. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention provides a head up display for firearms, wherein any of a variety of images can be selectively presented to an operator. In one configuration, a light valve is optically intermediate a beam generator and a hologram. The hologram includes a recorded image of an infinite image plane. The beam generator creates an illuminating beam that passes through the light valve and the hologram. The illuminating beam passes through the light to acquire the information in the light valve, then reconstructs the recorded infinite image plane from the hologram. The illuminating beam thus acquires any image in the light valve and upon reconstructing the image plane of the hologram, effectively displays the image of the light valve at the infinite image plan. 
   As the light valve can present a variety of images, or even a video, the present head up display provides a variety of images and hence data that can be presented. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
       FIG. 1  is a side elevational view of a firearm incorporating the head up display. 
       FIG. 2  is a side elevational view of a firearm incorporating a transmissive diffractive optic. 
       FIG. 3  is a side elevational view of a firearm incorporating an alternative design of the head up display. 
       FIG. 4  is a perspective view of a firearm incorporating the head up display, with selected components of the head up display shown schematically. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIG. 1 , a compact head up display  10  for a firearm  12  is shown. The head up display  10  can be cooperatively mounted to any of a variety of handheld, side and small arms such as pistols, rifles, shotguns, automatic, semi-automatic arms, as well as bows, collectively referred to as firearms. 
   The head up display  10  includes a base  20 , a diffractive optic  30  connected to the base, a laser  40 , a power source  50  for powering the laser, a light valve  60  and an image generator  70  operatively connected to the light valve. 
   Referring to  FIGS. 1-4 , the base  20  can be any of a variety of configurations that cooperatively engage the firearm  12 . The base can include any of a variety of clamping or mounting mechanisms such as a Weaver style, picatinny mount or dove tail engagement. It is also understood the base  20  can include a cover or shroud  22  to encase or substantially encase or house the remaining components of the head up display. 
   The base  20  is constructed to operatively retain the diffractive optic  30 , the laser  40 , the power source  50 , the light valve  60  and the image generator  70  relative to the firearm  12 . However, it is understood that aspects of the head up display  10  can be integrated into the firearm  12 . For example, the power source  50  and/or image generator  70  can be retained or housed in the firearm  12 . 
   The diffractive optic  30  is connected to the base  20 . Although the diffractive optic  30  is shown as fixedly connected to the base  20  it is understood the diffractive optic can be moveably connected to the base between an operable position and a closed (or transport) position. In the fixed or operable position, the diffractive optic  30  is disposed so that an operator of the firearm  12  can sight through the diffractive optic. It is understood the diffractive optic  30  can be reflective rather than transmissive as seen in  FIG. 2 . However, as the transmissive diffractive optic has a shorter optical path length than the reflective diffractive optic, it is preferred the diffractive optic be transmissive. 
   Preferably, the diffractive optic  30  has power. That is, the diffractive optic  30  is one of a focusing diffractive optic, diverging diffractive optic or collimating diffractive optic. In one configuration, the diffractive optic  30  is a hologram and is fixedly attached to the base  20 . In a further configuration, the diffractive optic  30  is a transmissive hologram. A transmissive diffractive optic provides that as an illuminating beam intersects the diffractive optic, the illuminating beam is diffracted by and passes through the optic. 
   In either the permanent or the moveable mounting of the diffractive optic  30 , it is understood the diffractive optic can be mounted to allow adjustment around one, two or three mutual perpendicular axes. Thus, an alignment of the diffractive optic  30  can be performed to accommodate variations or tolerances in components, as well as wear. 
   In one configuration, the diffractive optic  30  is a hologram with a recorded image of a ground glass screen. More generally, the recorded image is preferably that of an image plane at infinity. Thus, a transmissive hologram having a recorded infinite image plane is preferably employed. It is understood that images for reconstruction can be recorded in the hologram. However, as such images are permanent and cannot be changed during operation or use of the head up display  10 , the hologram can be recorded to provide the image plane at infinity. However, it is understood the image plane can be located adjacent an eye of the user (intermediate the firearm and the user) or anywhere from the firearm to infinity. Thus, the image plane can be located from adjacent the user to infinity. 
   The laser  40  is connected to the base for projecting an illuminating beam to intersect the diffractive optic  30 . The laser  40  can directly illuminate the diffractive optic  30 , or alternatively include folding or redirecting optics such as mirrors  42  which define the optic path from the laser to the diffractive optic. In one configuration, the illuminating beam from the laser  40  intersects the diffractive optic  30  at an inclined angle. That is, the principal ray of the illuminating beam is inclined relative to the normal of the diffractive optic  30 . 
   In one configuration, the laser  40  produces a diverging coherent beam. A preferred laser is a laser diode such as HL6321 MG manufactured by Hitachi. 
   In one configuration, the power source  50  includes at least one battery. Depending upon the anticipated power requirements, available space and weight restrictions, the batteries can be N-type batteries or AA or AAA batteries. It is understood that any type of power source, preferably portable and small in size can be utilized. The battery type power source can be disposable or rechargeable. 
   In one configuration, the base  20  includes a battery compartment sized to operably retain the batteries when subject to the recoil that can be experienced in a high caliber firearm. The battery compartment can be formed of a weather resistant, resilient material such as plastic and shaped to include receptacles for receiving the battery(ies) required for power. Further, the battery compartment be selectively closeable or sealable to prevent environmental migration into the compartment. 
   Alternatively, the firearm  12  can incorporate the power source  50 , including any associated batteries. In this configuration, the base  20  includes a pair of electrical contacts or pads for providing electrical communication between the head up display  10  and the firearm  12 . 
   The light valve  60  is connected to the base  20  and disposed optically intermediate the laser  40  and the diffractive optic  30 . The light valve  60  is selected such that upon illumination by the laser  40 , the image of the light valve is formed onto the diffractive optic (or intermediate optics or subsequent projection onto the diffractive optic). The light valve  60  can be any of a variety of devices including liquid crystal displays or cathode ray tubes. In one configuration, the light valve  60  is a transmissive element, such as a liquid crystal display (LCD). It is understood the light valve can be a predetermined pattern or image for illumination by the passing laser beam. 
   The image generator  70  is operably connected to the light valve  60  to cause an image to be formed in the light valve for projection onto the diffractive optic  30 . The image generator  30  can be any of a variety of mechanisms such as an integrated circuit or a computer chip. The image generator  70  can include a plurality of stored images that can be selected by the user in response to changing needs of the user. For example, different reticle images can be stored in the image generator  70 . In one configuration, the image generator  70  includes a user interface  64  for controlling the image generator and selecting the image to be formed in the light valve  60 . The image generator  70  can be powered by the power source  50 . An image generator  70  such as a reflective or transmissive LCD manufactured (or sold) by Kopin Corporation has been found satisfactory. 
   In a further configuration, it is contemplated the image generator  70  can include a video driver  66  for providing moving images to the light valve  60 . The image generator  70  can also include reticles and range finding information. 
   In a further configuration, the image generator  70  cooperatives with a night vision system  80  for protecting output from the night vision system to the light valve  60  and hence the diffractive optic  30 . The output signal from the night vision system  80  can be directly connected to the light valve, or passed through the image generator. The night vision system can be active or passive. The night vision system can be coupled or connected to the firearm, thereby allowing the operator to sight without looking through cumbersome goggles, monoculars or binoculars. A satisfactory night vision system  80  is manufactured (or sold) by ITT. 
   In a further configuration, the head up display  10  can include a receiver  68  or transceiver for receiving information from a remote source. Such information can include targeting information, as well as Strategic information, thereby allowing silent coordinated operations. As the images in the head up display are dynamic, the communication with remote sources  72  allows coordination between a plurality of head up displays. 
   Thus, in an alternative configuration, the night vision system  80  can be separate from the firearm  12  and head up display  10 . This configuration data from the night vision system  80  is provided via telemetry to the head up display  10 . The head up display  10  can include a receiver  68  (or transceiver) selected to acquire the data from the remote night vision system  80 . 
   Although the light valve  60  and the image generator  70  are described as separate elements, it is contemplated the elements can be incorporated or integrated into a single unitary structure, without departing from the present invention. 
   As seen in  FIG. 3 , it is understood that a collimating relay  64  can be disposed in cooperation with the light valve  60 , such that the diverging illuminating laser beam passes through a collimating lens to form a collimated beam. The collimated beam then illuminates the light valve  60  and passes through a focusing lens which focuses the collimated beam onto the diffractive optic  30 . 
   Referring to  FIG. 3 , in a further configuration, thermal stabilization of the laser  40  can be accomplished by employing a diffractive grating  44  off axis to the diverging beam via a beam splitter  46  such that a selected wavelength is introduced into the lasing medium of the laser, thereby controlling the output wavelength of the laser. 
   It is further contemplated that alignment of the light valve  60  with respect to the diffractive optic  30  can be accomplished by optically or physically moving the laser relative to one of the diffractive optic and/or the light valve. 
   In a further configuration, the laser beam can be split between an illuminating beam and a targeting beam TB. That is, the targeting beam is reflected from the firearm to intersect the target, while the illuminating beam passes through the light valve and onto the diffractive optic. 
   It is also contemplated that a range finder  62  can be Incorporated into the head up display  10 . Commercially available range finders can be integrated into the housing, such that the output of the range finder is input into the image generator or light valve. Thus, the head up display can also provide range information to the user. 
   Operation 
   In operation, the image generator  70  cooperates with the light valve  60  to form an image in the light valve. The laser  40  is powered by the power source  50  to create a diverging illuminating coherent beam, wherein at least a portion of the illuminating beam passes through the light valve  60  such that a resulting image is projected onto the diffractive optic  30 . The illuminating laser beam reconstructs the recorded image of the hologram and thus displays the image of the light valve  60  at infinity, such that the viewer looking through the diffractive optic sees the display of the light valve. 
   In the configuration of the head up display employing the video driver, moving images or varying images can be generated in the light valve  60  and thus “displayed” at the focal plane recreated by the hologram. Thus, range finding information can be readily displayed without requiring the user to move their head. 
   Although the present invention has been described in terms of particular embodiments, it is not limited to these embodiments. Alternative embodiments, configurations or modifications which will be encompassed by the invention can be made by those skilled in the embodiments, configurations, modifications or equivalents may be included in the spirit and scope of the invention, as defined by the appended claims.