US 3637315 A
A direct sight instrument permitting wide angle viewing of a target area with a minimal movement by the operator. Coordination of sight and weapon is provided by means of a combining glass to collimate an illuminated reticle with the direct observation of a target. The combining glass is supported for arcuate movement about a remote axis and simultaneously for rotation about the line of projection of the reticle to cause the combining glass and its axes and the reticle reflection to be at controlled angles with the operator's line of sight to the target. The sight provides for coordination of movement of the line of sight and an associated weapon.
Description (OCR text may contain errors)
United States Patent Harper 5] Jan. 25, 1972  DIRECT REFLECTING SIGHT Primary ExaminerRonald L. Wibert Assistant Examiner-Orville B. Chew, ll  Inventor: Kenna! Endwenv Attorney-Francis K. Richwine, Irving M. Freedman, Frank L.  Assigneer General Electric Company N euhauser, Oscar B. Waddell and Joseph B. Forman  Filed: Sept. 10, 1969  ABSTRACT PP ,705 A direct sight instrument permitting wide angle viewing of a target area with a minimal movement by the operator. Coor-  U 8 Cl 7 356/251 dination of sight and weapon is provided by means of a com-  In. .0 23/10 bining glass m collimate an illuminated reticle with the direct  i 350/174 observation of a target. The combining glass is supported for arcuate movement about a remote axis and simultaneously for rotation about the line of projection of the reticle to cause the  Reerences cited combining glass and its axes and the reticle reflection to be at FOR G PATENTS QR APPLICATIQNS controlled angles with the operators line of sight to the target. The sight provides for coordination of movement of the line of 595,118 3/1934 Germany sight and an associated weapon.
7 Claims, 2 Drawing Figures lllll PATENTEU JANZS Hi2 INVENTOR: NNARD w. HARPER,
B KQQZ k HIS ATTORNEY.
DIRECT REFLECTING SIGHT The invention herein described was made under a contract with the Department of Army.
BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to the sighting of a weapon, as for example a direct fire weapon, under conditions restricting movement of the operator's head, as for example, in the environment of a weapon mounted on a vehicle for movement relative to the vehicle and in which the weapon operator is restricted in movement by space within or weapon recoil or blast.
2. Prior Art Coordination of movement of a weapon and of an operator to move the weapon to cause intersection of trajectory and line of sight at the target is a problem that is inherent in the use of projectiles and is complicated by increases in weapon size, range and mobility of the weapons, increased speed of moving targets demanding greater lead angles and the more fleeting nature of targets requiring quicker response times. It has been common to use indicators or even optical instruments fixed to the weapon to define the line of sight. Such devices have provided for adjustment between line of sight and weapon axis to compensate for parabolic or other nonlinear trajectories but present certain limitations to an operator. Some systems place the operator so close to the weapon for aiming that he must move away to preclude injury, as for example by recoil or blast, when the weapon is fired. Other systems have required movement by the operator through extensive arcs about the axes of movement of the weapon or movement of the weapon about the operatorsposition. Some arrangements have included extensive or complicated optical devices. One solution provides for both operator and weapon to traverse about a common axis but it is difficult to have simple simultaneous movement about two axes.
One example of a vehicular mount is the primary gun on a tank fixed to a turret for rotation about a vertical axis inside the turret and for elevation about a horizontal axis that is usually close to or in the turret shell surface. This permits the operator to be located at the vertical axis but requires movement about the horizontal axis. Some direct fire weapons, particularly antiaircraft guns, have provided for an operator to ride the gun carriage as it revolves about the vertical axis and to swing in an are as the gun pivots about a horizontal axis with the operator using periscopic aiming devices.
It has long been recognized that many of these problems arise from the difficulties either in rotating a weapon simultaneously about two axes intersecting at the eye position or in designing a simple substitute. The existing substitutes are primarily those including periscopic aiming.
Most of the previous systems have also imposed serious limitations on the operators field of view, presented hardships in target acquisition and limited the amount of lead or lead angle that could be applied to compensate for target movement.
SUMMARY OF THE INVENTION The primary object of the invention is to provide a simple direct sight for a weapon that permits an operator to aim the weapon, with weapon movement in at least one plane with a minimal head movement by the operator.
Another object of the invention is to provide a gun sight that permits a wide angle of vision to an operator who is restricted in body motion and provides for mechanism to slave the gun to the sight (or vice versa) for coordinated movement and target designation.
Briefly in accordance with the invention, a combining glass is supported for accurate rotation with a remote axis by an elongated housing containing, at one end, drive and support mechanism interconnecting the housing and a sight base containing the remote axis. At the other end, the housing terminates in a viewing head mounted for rotation about an axis parallel to the remote axis. The viewing head which contains the combining glass is also linked to the drive mechanism so as to cause the head to rotate about its axis as it swings in an are about the remote axis. The drive ratio is fixed so that the c0mbining glass always interdicts the line of sight with one axis the one normal to the support axis of revolution-normal to the observers line of sight to the target. This arrangement has the effect of causing this one axis of the combining glass to appear to swing in an arc about the operator's eye and therefore permit the operator to move a weapon through a large angle while requiring only eye movement-without moving the remainder of the body or impairing the operator's field of vision. The drive and support mechanism also provides for an operational interface with the directional equipment of an associated weapon to coordinate movement of the weapon and line of sight to obtain intersect between the line of sight and trajectory at the target. An aiming point is provided through the use of an illuminated reticle projected onto the combining glass by means of a mirror in the housing and collimating lenses in the head.
BRIEF DESCRIPTION OF THE DRAWING FIG. I is a complete sight in elevation with portions cut away to show components.
FIG. 2 is a schematic illustration showing the relative alignment and motions of the sight housing and combining glass.
DESCRIPTION OF THE PREFERRED EMBODIMENT The embodiment of the invention, which is shown in elevation in FIG. 1, is a complete sight including an elongated SIGHT body 1 enclosing drive mechanism 2 at one and carrying sighthead 4 at the other. The body 1 is supported by a base 3 which permits attachment of the sight to a weapon or a structure supporting a weapon. Sight body 1 itself includes a housing 11 and a drive mechanism cover 12 and is attached to the sight base 3 by means of a bearing assembly 31, mounted between the drive mechanism cover 12 and stationary hub 32 affixed to base 3. The bearing assembly 31 which may be an ordinary ball or roller bearing permits rotation of the sight body about shaft 33 projecting from the stationary hub as an axis related to the installation position of the sight. This axis may be referred to as a sight base axis. Relative movement between the sight body and the base is controlled by the use of the drive mechanism 2 which includes stationary ring gear 20 attached to stationary hub 32 and a drive gear train including gears 21, 22, 23 and 24 interconnecting the stationary ring gear and both drive motor 25 and angular rate sensor 26 which provide for angular positioning of the sight about its axis of rotation either as driven by an operator or responsive to gun position.
Sight housing 11, at its end remote from the drive mechanism cover 12, terminates in a elbow which is truncated at 13 and carries a circular bearing 14 at the open end. The sighthead 4 includes a drum 40 having a driven pulley 41 at one end which is affixed to one race of bearing 14 to permit rotation of the sighthead about an axis which is perpendicular to the axis of the sight body and which is parallel to the axis-of shaft 33 about which the sight rotates. The sighthead 4 includes a combining glass 42 attached to the drum 40 by means of supports 43 secured to a flange 44 on the drum remote from pulley 41. The combining glass 42 is positioned with its vertical center line, which is the one running between the supports 43 as illustrated in FIG. 1, normal to the axis about which the sighthead rotates. The horizontal axis of combining glass 42, that axis normal to the vertical axis and horizontal as illustrated, is at an angle of 45 with the sighthead axis. This arrangement makes it possible to project the reticle image onto the combining glass for viewing by an operator. The reticle image is formed by means of a reticle lamp 15 within housing I I, projecting rays of light through reticle 16 along the axis of the sight body. This reticle projection is reflected along the sighthead axis by mirror 17 set at a 45 angle within the truncated portion of elbow l3. Collimating optics, as for example lenses 45 and 46, having a focal point on the reticle serve to project a collimated image onto combining glass 42 from which the reticle image is reflected to the operator to create an illusion of a reticle at target distance.
In order to present a good reticle and to correlate the horizontal and vertical axes of the combining glass with the field of view, and particularly a target area as viewed through the combining glass, it is necessary to rotate the combining glass about the sighthead axis consistent with the arcuate motion of the combining glass about the axis of rotation of the sight. This is accomplished by means of a sighthead drive 47, which includes a belt 48 interconnecting driven pulley 41 and a drive pulley 28 fixed to stationary shaft 33 for relative rotation with respect to the sight body. A belt cover 49 can be provided for protection. Coordination of movement between the sight and a weapon can be effected by use of resolvers 37 and 38 which are connected to the system through segment gears 35 and 36, meshed with gear 34, which is also attached to shaft 33.
Coordination of rotation of sighthead and combining glass with rotation of the sight itself about the axis defined by shaft 33, is accomplished by means of the pulley drive ratio, specifically the ratio of pulleys 28 and 41. The ratio is selected so as to maintain the vertical axis of the combining glass normal to the observer's line of sight to the target as is possible in view of certain aspects of the geometry of the situation which will be further explained.
FIG. 2 illustrates the orientation of the combining glass in a vertical plane with respect to the observers line of sight as the sight swings about its axis of rotation. In FIG. 2, the position of the sight base is indicated by 30 and the axis of shaft 33 by 37. The pulleys 28 and 41 are represented by 29 and 9 respectively. The courses of the belt in the various positions are represented by 10, and several lines of sight from a single eye position are represented by 5, 6, 7 and 8. Also shown in the multiple locations is the combining glass 42, which is shown in' section through its vertical axis.
Examination of FIG. 2 will also disclose that the relationship of the angle through which the combining glass must be rotated with respect to the sight body is not a simple linear relationship but is a trigonometric function of the angles of sight rotation and angle of change of line of sight. Therefore for each possible combination of sight length and distance from eye to axis of rotation of the sight, there is a different relationship of the angles and consequently a different drive ratio for the sighthead pulley. The complexity stems from the fact that as the line of sight swings away from alignment with a radius of the are described by the sighthead, there is a change of ratio between the changes of angles of sight rotation and line of sight deflection.
This complexity would seem to indicate that a complete solution would include elliptical pulleys to provide for less movement of the driven pulley as the sight rotation reaches 90 in an arrangement such as the embodiment illustrated. However practical application has shown that the invention has utility with circular pulleys-with some compensation by means of a slight eye shift longitudinally of the line of sight. In practical application the pulley ratio can be established empirically by physical measurement beginning with measurement of the available space and view angle to obtain sight location, size and angle of rotation. Thereafter the extreme positions and angles of sighthead can be measured and an appropriate linear drive ratio calculated.
In one actual mechanization within the parameters of the preferred embodiment, the pulley drive ratio used, expressed as movement of driver to driven, was 2:1 requiring the actual pulleys to be dimensioned as l:2 (driver to driven). In this mechanization, sight rotation was I50 and sighthead rotation relative to the sighthead was 75.
OPERATION OF THE SIGHT The device as described constitutes what is generally referred to as a wide angle sight because it permits an operator to maintain an unrestricted view over a wide angle of vision and to be able to align the mechanism to describe both azimuth and elevation of the line of sight to a target by movement of the sight. The small combining glass which is movable, serves the same purpose as a large segment of a spherical combining glass centered on the operators eye, in those instances in which further provision is made for traversing the sight about the operator. In the vertical plane represented in FIG. 2, the combining glass, while retaining its angular relationship with the line of sight, can be moved in an arcuate path which is a practical substitute for a spherical combining glass centered on eye position. As a practical matter, the motion of the sight construction shown is not exactly linear as it could be if the pivotal axis 37 were located within the field of vision so that the geometry would be that of a circular segment viewed from a plurality of places along the diameter of the circle. This atrangement, of course, would be impractical, as it would interfere with the field of vision and detract from the solution. If the axis 37 indicated in FIG. 2 were superimposed on the eye position 18, the relationship would be linear (and lzl and no compensation necessary. In the present case, however, compensation to the extent needed is obtained through eye movement along the line of sight through axis 37. As a practical matter, this movement is easy to provide for since it is only forward and backward head motion and is of relatively low magnitude, as for example of the order of the distance between the axis of sight rotation and the axis of the sighthead as a maximum.
The system has utility in vehicularly mounted weapons in which an operator can occupy va turret which is rotatable about an axis. In particular, the sight would have significant utility when used in a turret in which the operator can assume an eye position coordinated with the vertical axis of rotation for traverse of the turret and the weapon and in which coordination of the line of sight and the elevation of the weapon can be coordinated by synchronizing mechanisms, either with or without compensation for nonlinear relationships such as a parabolic trajectory. In the alternative, the sight could be used to control the traverse of a weapon by placing the sight axis in a normally vertical plane within a turret which can rotate about a horizontal axis to provide for weapon elevation.
1. A direct sight instrument permitting wide angle viewing of a target area comprising a sight base adapted for mounting on another structure and including a shaft defining a sight drive axis, an elongated sight body mounted near one end thereof for. rotation of its length about said shaft in a plane normal to said shaft, a sighthead mounted on said body at its end remote from said shaft for rotation about a sighthead axis parallel to said shaft, a planar optical combining glass attached to said sighthead for rotation therewith about said sighthead axis, said combining glass being oriented with respect to said sighthead with the intersection of two mutually perpendicular axis in the plane of the glass lying on said sighthead axis with one of the said perpendicular axis in the plane of the glass being normal to, and the other of the said perpendicular axis in the plane of glass being at 45 to said sighthead axis, said body also including means for projecting light from an illuminated reticle along said sighthead axis onto said combining glass, said sight base and said sight body also including drive means for rotating said sight body about said shaft and for coordinating said rotation with movement of another body, said sight also including sighthead drive means interconnecting said base and said sighthead for rotating said sighthead about said sighthead axis responsive to rotation of said sight body about said shaft with a predetermined drive ratio.
2. A direct viewing wide angle optical sighting instrument comprising an optical combining glass mounted for rotation about a sighthead axis which intersects a planar surface of said glass with a minimum angle of 45, a sight base having means defining a sight axis of rotation parallel to said sighthead axis, and body means interconnecting said combining glass and said base and having drive means interconnecting with said means defining a sight axis for causing said combining glass and said sighthead axis to move in an arc about said sight axis and causing said combining glass to simultaneously rotate about said sighthead axis with a predetermined ratio of rotation about the two axis whereby rotation of said sight about said sight axis will cause said combining glass to sweep through an arc while retaining a constant angular orientation with respect to a point in the plane containing the arc swept, said point being spaced from said sight axis, said body means containing means for projecting collimated light onto said combining glass parallel to said sighthead axis.
3. The sight of claim 2 wherein said drive means also includes power means for rotating said body means about said sight axis and said body means also includes rate means for coordinating rotation of said body means about said sight axis with movement of a foreign body.
4. A wide angle direct sight instrument comprising a sight base including sight drive means and a first bearing means defining a sight drive axis normal to a selected plane of lines of sight from an operator eye position to a target area, an elongated sight housing mounted proximate one end thereof on said bearing means for rotation about said drive axis in a plane parallel to said selected plane, said elongated sight housing terminating in a second bearing means spaced from said drive axis, a sighthead mounted on said second bearing means for rotation about a sighthead axis parallel to said drive axis, said elongated sight body including means for producing an illuminated reticle and for projecting light from said reticle along said sighthead axis, said instrument also including optical members for collimating said light, said sighthead also supporting a combining glass interdicting one said line of sight with one line on the surface of said glass normal to said line of sight and with lines normal to said one line on the surface of said glass being at 45 to said selected plane, and sighthead drive means interconnecting said sighthead and said sight drive means for rotating said sighthead about said sighthead axis responsive to rotation of said sight about said sight drive axis with a predetermined ratio of rotation about the two axes whereby rotation of the sight about the sight drive axis will cause the combining glass to swing in an arc in said selected plane and to maintain constant its angular relationship with each said line of sight as it is interdicted.
5. A wide angle direct view sighting apparatus comprising:
a. a combining glass;
b. mechanical means to move said combining glass about a sight base axis to sweep out an arc in one plane of vision established through an operator eye position perpendicular to said sight base;
said mechanical means including rotating sighthead means for supporting said combining glass and for rotating said combining glass about a second axis parallel to and spaced from said sight base axis responsive to arcuate movement of said combining glass about said sight base axis whereby said combining glass may be caused to interdict radially divergent lines of vision from said eye position in said plane over a wide angle with a minimum of obstruction of vision from said eye position while maintaining a predetermined angular relationship with said second axis; and
. reticle means including a reticle, a source of light and optical means for projecting light from said source through said reticle, collimating said light and projecting it onto said combining glass, said combining glass reflecting said collimated light to said eye position whereby an operator having his eye at said position will see a virtual image of said reticle at infinity superimposed on his view whereby said virtual image may constitute an aiming point.
. The sight of claim 5 wherein:
said mechanical means includes, in addition to said rotatin means,
l. ase means including bearing means defining said sight base axis,
2, housing means supported on said bearing means for rotation of said housing means about said sight base axis,
3. an elongated body interconnecting said housing means and said rotating sighthead means and 4. direct drive means interconnecting said rotating sighthead means and said base means for rotating said sighthead means with said combining glass about said second axis responsive to rotation of said housing means about said sight base axis;
. said reticle and said source of light of said reticle means are located in said elongated body; and
said optical means includes collimating lenses located in said rotating sighthead means for projecting said collimated light parallel to said second axis.
The sight of claim 6 wherein:
. said direct drive means has a drive ratio which will maintain said combining glass at a predetermined angular relationship with each said line of vision from said eye position in said plane as it is interdicted by said combining glass as it sweeps out said arc about said sight base axis.