Abstract:
A weapon sight of the kind comprising a lens having a partially reflecting surface, a light source spaced from the lens for emitting light towards said reflecting surface to produce a light spot by direct imaging of said light source on said surface to be superimposed on a target when sighting through the lens. For adjustment of the location of the light spot on the reflecting surface when observed from a defined fixed position, the sight includes a device for displacement of the light source, comprising a miniature drive motor or element operatively connected with the light source.

Description:
FIELD OF THE INVENTION  
       [0001]     The invention relates to a weapon sight to be used on rifles, guns, and machine guns.  
         [0002]     The weapon sight is of the kind comprising a lens having a partially reflecting surface; a light source spaced from the lens for emitting light towards said reflecting surface to produce a light spot by direct imaging of said light source on said surface to be superimposed on a target when sighting through the lens; and means for adjustment of the location of the light spot on the reflecting surface when observed from a defined fixed position, by displacement of the light source.  
         [0003]     A weapon sight of the kind referred to is disclosed in GB-A-2 292 465.  
         [0004]     Usually, the lens is located at one end of a light channel formed by an elongate housing, and the light source is located in the channel. At sighting, the light spot and the target are observed through the light channel from the other end thereof.  
       BACKGROUND OF THE INVENTION  
       [0005]     If the sight at zeroing has been calibrated for a distance from the weapon (sight) to the target of 100 m the ballistic curve of the projectile and the sight line will intersect at the distance 100 m. At very short range (up to 20 m, depending on the distance between the weapon barrel of the and the sight), the ballistic curve will pass under the sight line; between 20 m and 100 m, the ballistic curve will pass over the sight line, whereas the ballistic curve will pass under the sight line at distances longer than 100 m.  
         [0006]     It is desired to compensate automatically for said deviation at other distances than that the sight has been calibrated for by zeroing. However, weapons are used not only for shooting more or less horizontally but also for shooting at an angle upwards or, more often, downwards e.g. from a helicopter. Also a moving target may be aimed at. It is therefore desired to adjust the sight automatically not only for the different distances to the target but also in dependence of the different parameters involved in sighting under the conditions mentioned. At the present state of the art miniature range finders of infrared type as well as miniature angular gauges are available. The present state of the art also includes binoculars with integrated compass. Measurement of the direction in which the shooter is aiming in combination with measurement of the distance to a moving target enables calculation of the speed at which the target moves. Alternatively, the speed can be measured by GPS (global positioning system). With the parameters easily available the aiming point can be controlled in dependence thereof in order to have the weapon directed in different positions towards a target, even towards a moving target, located at different distances from the shooter. However, control of the aiming point by mechanical adjustment thereof to different positions in different directions in dependence of said parameters involves great complications.  
       BRIEF SUMMARY OF THE INVENTION  
       [0007]     The primary object of the invention is to provide a sight of the kind referred to above with increased possibilities to take into consideration several parameters simultaneously for automatic adjustment of the light spot vertically as well as horisontally.  
         [0008]     A further object is to increase the precision and speed of the adjustment and to facilitate the use of the sight.  
         [0009]     According to the invention these and other objects which will be apparent from the description which follows are achieved by a sight of the kind referred to herein, which comprises a lens having a partially reflecting surface; a light source spaced from the lens for emitting light towards said reflecting surface to produce a light spot by direct imaging of said light source on said surface to be superimposed on a target when sighting through the lens; and a miniature drive motor operatively connected with one of the light source and the lens for displacement of the light source or the lens, respectively, in one of two mutually perpendicular directions for adjustment of the location of the light spot on the reflecting surface when observered from a defined fixed postion.  
         [0010]     Further features of the invention are defined in the dependent claims. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     Illustrative embodiments of the sight of the invention will be described in more detail in the following description with reference to the accompanying drawings in which  
         [0012]      FIG. 1  is a diagrammatic axial cross sectional view of a weapon sight of the kind referred to herein,  
         [0013]      FIG. 2  is a graph showing the sight line and the ballistic curve of a projectile,  
         [0014]      FIG. 3  is a diagrammatic side view of the weapon sight of the invention,  
         [0015]      FIG. 4  is an enlarged perspective view of the light source and a supporting structure thereof according to a first embodiment of the invention  
         [0016]      FIG. 5  is an enlarged perspective view of a light source comprising a diode array (VCSEL), and the supporting structure thereof according to a second embodiment of the invention,  
         [0017]      FIG. 6  is a diagrammatic view of the light source and the supporting structure according to a third embodiment of the invention,  
         [0018]      FIG. 7  is a diagrammatic view of the light source and the supporting structure according to a fourth embodiment of the invention, and  
         [0019]      FIG. 8  is a diagrammatic view of another embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0020]     The weapon sight disclosed in  FIG. 1  is of a well known prior art embodiment comprising a light channel formed by an outer tube  10  to be fastened to the barrel, the breechblock, or a specially designed sight holder of a weapon on which the sight shall be used, and an inner tube  11  which is mounted in the outer tube at one end  12  and is fixed at the other end by adjustment means  13 , allowing adjustment of the longitudinal axis of the inner tube horizontally and vertically in relation to the longitudinal axis of the outer tube as is necessary in order to adapt the sight to the weapon on which it is used. In said one end of the inner tube a double lens  14  is provided having a layer  15  between the lenses, said layer reflecting red light. Inside the inner tube a light source  16  e.g. an LED (Light Emitting Diode) or RCLED (Resonant Cavity Light Emitting Diode) is mounted to project a beam of red light with minimal dispersion on layer  15  where the light beam forms a red spot to be used as an aiming point. The light beam is reflected by the layer  15  through a face-ground glass plate  17  having an anti-reflection layer on the side thereof facing the right end of the light channel. Sighting takes place through the light channel formed by the inner tube from the right end thereof the sight line being indicated by a dot-and-dash line  18 .  
         [0021]     Adjustment of the sight at zeroing could be effected with the sight adjusted for a distance to the target of 100 m. Since the ballistic curve described by the projectile deviates downwards from the weapon along a parabola the sight should be adjusted such that the ballistic curve and the sight line intersect at the distance 100 m. This is illustrated in  FIG. 2  wherein the horizontal is indicated at H, the sight line at S and the ballistic curve at B. The sight is shown at  19  and the barrel of the weapon on which the sight is mounted is fragmentarily shown at  20 . The distance of 100 m from the weapon is indicated by a dash-dotted line D. The intersection between the sight line and the ballistic curve is indicated at  21 .  
         [0022]     If the sight line and the ballistic curve do not intersect at a distance of 100 m at zeroing of a weapon having a sight of the type disclosed in  FIG. 1  the adjustment mechanism  13  is used to adjust the sight line to such position that the intersection will be located at 100 m. The adjustment mechanism is then calibrated so that it indicates a distance of 100 m.  
         [0023]     In some cases, it is useful to adjust the sight so that the bullet will ram the target 3-5 cm above the line of sight at 100 m. By this, it is achieved that the shooter has got some security against misjudgment of the distance to the target; for most popular hunting and military caliber&#39;s, a zeroing according to the above will increase the useful range of the weapon up to about 230 m.  
         [0024]     When the weapon with the sight described is being used at even longer distances, the light source has to be adjusted in order to have the sight line and the ballistic curve to intersect at the actual distance. However, the distance is only one parameter that has to be taken into consideration. Other parameters are the angle between the sight line and the horizontal, the speed of a moving target, influence of the wind, the speed of the projectile, the temperature of the air, and the type of ammunition used in the weapon.  
         [0025]     At the present state of the art these parameters can be determined and be processed by a computer for controlling the position of the light source vertically and horizontally in dependence of the determined values of the parameters involved. Miniature drive motors such us piezoelectric or magnetostrictive motors or elements, stepping motors, and linear motors, are available today and are small enough to be integrated with a sight of the kind referred to herein.  
         [0026]     In  FIG. 3  such integration is illustrated. On a mounting frame  22  which may be the tube  11  disclosed in  FIG. 1  lens  14  with reflecting layer is mounted by means of a connection element  23 . Light source  16  such as an LED or RCLED is mounted on frame  22  by means of a miniature motor  24  such as a piezoelectric motor including a slide  25  which is movable in the vertical direction the light source  16  being supported by the slide. The light source accordingly can be shifted vertically to different positions by means of the motor, and the operation of the motor is controlled by output signals from a computer so that the light spot generated by the light source when observed from a defined fixed position at the right end of the sight will be positioned automatically in dependence of relevant parameters supplied to the computer, such that the sight line will intersect the ballistic curve on the target.  
         [0027]     Motor  24  can be located in a box at the lower side of frame  22  so that only slide  25  with light source  16  at the upper end thereof projects from the upper side of the frame.  
         [0028]     In  FIG. 3 , only the position along a vertical axis, the Y-axis, is controlled. In the embodiment disclosed in  FIG. 4  motor  24  having light source  16  mounted to slide  25  thereof, also the position along a horizontal axis, the X-axis, is automatically controlled. In  FIG. 4  motor  24  is mounted to the slide  26  of a second motor  27 , slide  26  being movable along the X-axis by means of motor  27  while slide  25  is movable along the Y-axis by means of motor  24 . Light source  16  accordingly can be adjusted in two mutually perpendicular directions by means of the two motors  24  and  27 .  
         [0029]     The same result can be achieved by means of a single motor  24  if the light source is a diode array (Vertical Cavity Surface Emitting Laser, VCSEL)  28  mounted to slide  25  of motor  24 , as shown in  FIG. 5 . The slide is movable by means of motor  24  along the Y-axis, and the diode array extends at right angles to slide  25 , i.e. along the X-axis. In this case the position vertically is controlled by motor  24  while the position horizontally is controlled by activating the proper diode in diode array  28 .  
         [0030]     In a modification of this embodiment motor  24  is mounted with the associated slide  25  movable along the X-axis while diode array  28  extends along the Y-axis.  
         [0031]     In the embodiment disclosed in  FIG. 6  slide  25 , to which light source  16  is mounted, is displaceable axially in a tube  29  fixedly mounted to frame  22 . A two-armed lever  30  is pivoted on a fixed support  31  at  32 . One arm of the lever supports slide  25  at the lower end thereof, the other arm being engaged from below by a piezoelectric element  33  which is controlled by electric current supplied at  34 . The piezoelectric element will be lengthened or shortened by the voltage applied to the element being changed, in order to adjust the vertical position of the light source.  
         [0032]     The piezoelectric element  33  in the embodiment described with reference to  FIG. 6  can be replaced by a magnetostrictive element.  
         [0033]     In the embodiment according to  FIG. 7 , a pinion  35  on an electric stepping motor  36  engages a rack  37  on slide  25 . Stepping motor  36  is energized at  34  to rotate in either direction in order to adjust the vertical position of light source  16  by axial displacement of slide  25  in tube  29 .  
         [0034]     In  FIG. 8 , another embodiment of an adjustable sight according to the present invention is shown. Here, the LED is fix in the tube  10 , which tube simultaneously serves as an inner tube and as an outer tube. The sight adjustment is performed by changing the angle of the double lens  14  by means of the piezo-electric stack  33 . In the embodiment shown, an elongation of the piezoelectric stack  33  will shift the sight line upwards, i.e. the bullet will hit the target on a lower spot. In another embodiment, the piezo-electric stack  33  is placed on the upper part of the tube  10 , which will give a lower sight line when the piezo-electric stack is elongated, i.e. a higher bullet hit position. The embodiment according to  FIG. 8  is advantageous in that the diameter of the tube  8  can be kept at a minimum. Obviously, the translation of the double lens  14  can be performed by other means than a piezo-electric stack, e.g. all other linear movement means that have been described in connection with the other embodiments of the invention.  
         [0035]     Finally, one further embodiment will be described. In some cases, it could be useful to combined the diode array of  FIG. 5  with the movable lens of  FIG. 8 . By combining these two embodiments, side correction of the sight line can be achieved by lighting different diodes of the diode array, whereas horizontal correction of the sight line can be achieved by means of the movable lens. Of course, it is also possible to use both a moving light source and a moving lens.  
         [0036]     Within the scope of the invention the embodiments described above may be combined in different ways, or one embodiment may be modified by guidance of another embodiment described herein.