SIGHT FOR A HAND FIRE ARM

Abstract: A sight intended to be attached to a hand fire arm com­ prises an enclosure (2), an optical element (8) arranged in the enclosure, a reticule (31) positioned in the focal plane of the optical element, an illumination device (36) for the reticule and a positioning device (11, 20) for the optical element. The optical element (8) is made of a plastic material and can thus be made thin. The whole sight is made of molded plastic details, which entails that the sight is very cheap, compact and impact resistant. The positioning device for the sight is arranged inside the enclosure and comprises a first positioning arm (11) for ho­ rizontal positioning of the optical element and a second posi­ tioning arm (20) for vertical positioning. The reticule (31) and the illumination device (36) are arranged in an exchangable insert (33) or a sleeve, which is positioned and locked in a recess (34) in the upper portion of the enclosure. The optical element can be a semitransparent mirror or a holographic optical element.

Description: REFLECTING SIGHT The present invention relates to sights for fire arms, especially handfire arms. The sight is of the type reflecting sight. The principle for a reflecting sight is previously known and used and means that a semitransparent mirror is placed in the sight line of the eye at aiming. By means of the semitransparent mirror, cross-hairs or a similar reticule are superimposed on the target. The cross-hairs are projected by means of a collimator against the mirror, which is plane. Alternatively, the mirror is concave and the reticule is positioned in the focal plane-of the mirror. At such previously known sights, the means which comprises the mirror are expensive and difficult to manufacture with the necessary precision. A previously known method of manufacturing such a glass body having a concave, semitransparent mirror, is to use a cylindrical glass body having one side plane and the second side convex. At the convex surface, a semitransparent material is applied, e.g. a thin gold layer or aluminum layer. A second cylindrical glass body having a plane surface and a concave surface is positioned with the concave surface against the semitransparent convex surface and the two bodies are cemented together. The glass body thus produced must have a certain thickness for a certain smallest diameter, which depends on the geometri of the sight. The thickness is also dependent on how long focal distance which can be allowed. All together this glass body will be heavy and it is thus unsuitable for use at a sight for a handfire arm. Moreover, the enclosure, which is to maintain the glass body must be manufactured such that it is able to maintain the heavy glass body at the heavy accelerations, which can occur at a handfire arm. The object of the present invention is to provide a reflecting sight having a concave semitransparent mirror. The sight should be cheap to manufacture, light and very impact resistance and must not obstruct the sight angle in the lateral direction. In previously-known sights having the heavy glass mirrors, this is impossible since the glass body is too heavy. If the mirror is manufactured from a thin glass disc, which is cut from a glass sphere, i.e. an equally thick, spherical disc, having the concave or the convex surface semitransparent as mentioned above, the glass plate will be very brittle and can hardly be used in handfire arms due to the blows, shocks and accelerations which occur. If the glass plate is too thick, a distortion of the target area is obtained, partially due to the parallax aberration and partially due to a certain lens effect. This problem is solved according to the present invention by the use of a thin, spherical, semitransparent disc manufactured by a plastic material. The plastic material is not brittle but tenacious and is suitable to resist the accelerations which occur in a handfire arm. The plastic plate is very light, which means that the construction which maintains and supports the mirror can be made less complex and less bulky. Since the plastic disc is thin, the distortion and the parallax aberration are minimal. We have succeeded to manufacture such a mirror, which is suitable for a reflecting sight. The plastic material used in this embodiment is acrylic plastic and the mirror has a thickness of about 0,8 mm, a diameter of about 25 mm and a focal distance, i.e. a spherical radius of about 50 mm. Since the mirrors very light, it is possible to use a light supporting device and a light enclosure made of molded plastic. Moreover, the enclosure which encloses the sight, can have a small material thickness and be manufactured such that a maximum sight angle is achieved. In this regard it is essential that the enclosure does not obscure the sight in an unnecessary degree in the lateral direction. In the downward drec- tion, the fire arm will obscure the sight in any case and in the upwards direction the need of free sight angle is not so great, since most movable targets move in the lateral direction. According to the invention, the side surfaces of the enclosure are shaped as a trunkated cone, while the positioning means for the sight and the illumination device for the cross-hairs are positioned above and below said cone. Finally, the sight must be positioned such that the cross-hairs can be positioned to be superimposed on the target at the actual mounting on the fire arm. This positioning means can be provided so that the direction of the enclosure in relation to the fire arm is adjusted, a so-called outer positioning means. However, according to the present invention there is used an interial positioning means, by means of which the orientation of the mirror inside the enclosure is adjusted. In this way a more safe mounting of the enclosure on the fire arm can be achieved. The positioning means according to the invention has long lever arms, whereby an accurate adjustment can be achieved. The reticule in the sight according to the present invention comprises a plate having cross-hairs or similar etched therein, whereby the cross-hairs are positioned in the focal plane of the mirror. For illuminating the cross-hairs there is preferably used a plastic rod comprising fluorescent material. When the fluorescent material is illuminated by the daylight, a proportionally great portion of the fluorescent light is emitted through the edge surfaces of the rod, which thus is arranged for illuminating the cross-hairs. This technique is previously known per se. Alternatively conventional light sources can be used as a light emitting diode, a filament lamp, a radioactive luminiscent material or combinations thereof. According to the present invention, both the reticule, i.e. the cross-hairs or similar, and the illumination device are exchangable. The invention also contemplates a new type of light source incorporating multiple reticule patterns. The light source is made of a tubular or annular body or sleeve of a transparent material which incorporates a fluorescent material or dye. One end surface is masked off, e.g. photographically with paint, print etc. Several different reticule patterns are applied or releaved and are spaced by an equal angle or distance. The sleeve is positioned in an annular recess in the enclosure and is rotatable around the horizontal axis of the sight. A snap locking device is arranged to permit the sleeve to be rotated in steps corresponding to said angle o( in order to position one of said reticules in correct position to be used as a reticule and be reflected by the mirror to the observer's eye. The fluorescent dye in the sleeve will be excited by the scattered daylight and emits a red light through the end or edge surface as described above for the illuminating rod, and illuminates the reticule to be used. According to the invention the mirror can be replaced by a so-called holographic diffraction optical element, which is a newly developed optical element or film having the property to diffract light of a certain wavelength but does not affect light of other wavelengths. Thus, more than 90 % of the daylight from the aiming area can pass this optical element, while more than 90 % of the red light from the reticule is reflected or diffracted by said element. The holographic element essentially consists of a photographically active material or gelatine positioned on a plastic substrate or film. The element can be enclosed or sandwiched between two discs of glass or plastics in order to enhance the rigidity. The element can be given the properties necessary for the purpose of this invention as is more clearly disclosed below. In order to explain the invention, several embodiments of the invention are described below by reference to the appended drawings. However, the invention is not limited to the embodiments described, which are only shown for purpose of illustration. On the drawings Fig. 1 is a cross-sectional view through a sight according to the present invention. Fig. 2 is an end view of the sight according to Fig. 1 taken along the line II-II in Fig. 1 Figs. 3, 4 and 5 are perspective views of details comprised in the sight according to Fig. 1. Thus, Fig. 3 is a perspective view of the vertical positioning device. Fig. 4 is a perspective view of the mirror craddle. Fig. 5 is a perspective view of the horizontal positioning device. Fig. 6 is a perspective view of the reticule sleeve. Fig. 7 is an enlarged plan view of the encircled area VII of Fig. 6. Fig. 8 is a side view and shows the reticule sleeve mounted to the sight enclosure. Fig. 9 is an enlarged sectional view of the encircled area IX in Fig. 8. Fig. 10 is a schematic view of a holographic optical element according to the invention. Fig. 11 is a view similar to Fig. 10 of a second holographic optical element. Fig. 12 is a view similar to Fig. 11 of a third holographic optical element according to the invention. Fig. 13 is a view similar to Fig. 10 and shows a combination of the holographic optical elements of Figs 11 and 12. Referring to Fig. 1 there is shown a sight 1 according to the present invention. The sight comprises a sight tube 2, which has a trunkated conical shape as appears from Fig. 2. The tube is closed by a front transparent plastic disc 3 supported by a front sleeve 4 and a back transparent plastic disc 5 supported by a back sleeve 6 in order to protect the interior of the tube. The front and the back sleeves are attached to the tube by snap action, whereby a closed, dustless, essentially cylindrical or cone-shaped inner space 7 is defined. Inside this space, there is a concave, semitransparent mirror 8. The mirror is made of a thin, transparent essentially spherical plastic disc having a thin gold layer or aluminum layer or similar applied preferably on the concave side of the mirror. The disc has a constant material thickness and is supported by a mirror craddle 9. The mirror craddle has a groove for supporting the mirror. The mirror is attached to the mirror craddle by means of an adhesive or cement, which does not provide any distortion of the shape of the mirror. The mirror craddle 9 is pivotable around a horizontal supporting axis 10, which is attached to a first positioning arm 11 for horizontal positioning, which arm 11 is journalled in the tube 2 around a vertical axis 12. The positioning arm comprises two portions 13 and 14 positioned on each side of the axis 12. The front portion 13 supports the mirror craddle 9 and,the back portion 14 comprises a threaded hole 15 having a horizontal axis. The hole 15 is placed at a greater distance from the vertical axis 12 than the supporting point 10 of the mirror craddle. A threaded screw 16 cooperates with the threaded hole 15 in the back portion of the positioning arm, and the screw 16 is rotatably but axially non-movably arranged in the tube 2. The screw 16 has a comparatively big head 17 and has an essentially horizontal axis. The positioning arm comprises a spring 18, which is integrally formed with the arm, preferably on its back portion 14. The spring 18 biases the positioning arm around its vertical axis 12 such that the head 17 of the screw is brought to abut the tube 2. The positioning arm 11 is placed in the lower portion of the enclosure and does not obscure the sight area. By means of said first positioning arm 11, the angle position of the mirror in the horizontal direction can be adjusted by the screw 16 being threaded in the hole 15. The angle position of the mirror in the horizon tal direction is adjusted by rotating the mirror craddle around its own supporting axis 10 by means of a second positioning arm 20. The craddle 9 comprises a spring 19 integrally formed with the craddle, the spring biasing the mirror craddle anticlockwise around the supporting point 10 as seen in Fig. 1. The spring abuts a shoulder of the front portion 13 of the first positioning arm. The second positioning arm 20 is journal led around a horizontal supporting point 21 and comprises a front 22 and a back 23 portion positioned on each side of the supporting point 21. The positioning arm is cut from an essentially tube-shaped body and has a shape which appears from Fig. 3. Thus, the positioning arm 20 will always be placed immediately close to the side walls of the tube 2 and thus minimally disturb or obscure the sight area. In the back portion 23 of the positioning arm there is an essentially vertical, threaded hole 24, and on the front portion 22 there is a contact surface 25, which cooperates with a corresponding contact surface 26 shaped on the back portion of the mirror craddle. A threaded screw 27 having a comparatively big head 28 cooperates with the threaded hole 24 in the back portion 23 of the positioning arm, and the head abuts the tube 2. The screw 27 with the head 28 is rotatably but axially non-movably arranged in relation to the enclosure. The spring 19 of the mirror craddle 9 entails that the positioning arm 20 is biased anticlockwise as seen in Fig. 1 by means of its contact surfaces 25 and 26, whereby the head 28 of the screw is biased against the tube 2. A rotation of the screw 16 of the horizontal positioning arm 11 and the screw 27 of the vertical positioning arm 20 entails that the arms are pivoted around their supporting points 12 and 21, respectively, whereby the mirror is adjusted. Due to the fact that said positioning points are arranged relatively close to the mirror, there is achieved a great gearing and one revolution of the positioning screws corresponds to a comparatively small angle adjustment of the mirror. In this way an accurate positioning can be achieved. The lever arms and the pitch of the threads of both positioning devices are so arranged that one revolution of each positioning screw corresponds to the same angle change in horizontal and vertical direction. The head 17 of the screw 16 is provided with a portion which comprises teeth 29 or similar having a certain pitch. An elastic snap device 30 cooperates with the teeth and provides a stepped resistance against the rotation of the screw. Each tooth corresponds to a certain small angle adjustment of the mirror and the mirror can be adjusted by counting the number of teeth which are passed at the positioning, which gives a measure of the angle change. The same is true for the screw 27 of the vertical positioning arm 20. A special snap device 30 is adapted for both heads of the two screws and is made in one piece. Thus, there is needed only one element for performing two functions, and the number of parts of the sight according to the invention is decreased by one. Simultaneously, the snap device 30 is a support for the back plastic disc 5 as appears from Fig. 1. A reticule 31 is positioned in the focal plane of the mirror 8. A hole 32 is made in the upper portion of the enclosure. The reticule is composed of a metal plate having cross-hairs etched therein, or a photographic film including a photographically provided cross-hairs. Other reticules can also be used such as a standing triangle, a circle, a graduated scale and similar. The mirror according to the invention has comparatively short focal distance, which means that the sight can be made small and compact and that the mirror enlarges the cross-hairs with a big ratio, whereby cross-hairs with smaller dimensions can be used. The cross-hairs 31 is positioned in an insert 33, which is replacably adapted on the upper side of the sight in a recess 34. The insert is locked in place by a locking plate 35. The insert also comprises an illumination device for the cross-hairs. In the embodiment shown the illumination device 36 comprises a plastic rod 37, in which is enclosed a fluorescent material or dye, which after illumination emits red light. The plastic material is essentially transparent. The plastic rod has parallel side surfaces and two edge surfaces. Below and beside the plastic rod there is a reflecting material. When daylight penetrates the plastic rod, the fluorescent material is exited inside the plastic rod and emits light within a certain wavelength range, which depends on the material used. The more incident daylight, the more fluorescent light is emitted. However, all light emitted from each particle in the plastic material and which hits the parallel side surfaces of the material under a greater angle than the total reflection angle, will be enclosed inside the plastic rod and totally reflected against said side surface until the light reaches an edge surface, where the liyht can leave the plastic rod. In this way, a proportionally big portion of the fluorescent light is emitted through the plastic rod edge surfaces. One end surface of the plastic rod can be placed immediately above the cross-hairs, whereby a very efficient illumination of the cross-hairs is achieved. This principle is previously known per se. Of course the illumination can be made in other ways, e.g. by a light emitting diode or a filament bulb and a battery. Night illumination can be achieved by a radioactive fluorescent material in said plastic rod or in other per se previously known manners. In Fig. 6 a second embodiment of the reticule according to the invention is shown. The reticule is placed on a plastic sleeve 40 having an annular or cylindrical shape. As mentioned previously, the plastic material of the sleeve is essentially transparent and includes a fluorescent dye which upon excitation of scattered daylight emits red light, which to a great portion leaves the sleeve.through its edge surfaces 41 and 42. One portion 43 of the first edge surface 41 is masked off by any suitable method and reticule patters 44 are created in the masked area as is evident from Fig. 7. In Fig. 7, there is shown three reticule patterns but it is realized that this embodiment is not limited to the number and nature of reticule patterns shown. The reticule patterns are spaced by a certain angle Oc as shown in Fig. 7. The sleeve is mounted on the enclosure in a correspondingly shaped recess 45 so that only one of the reticule patterns is placed opposite to a hole 46 in the enclosure. The angular position of the sleeve can be altered by rotating the sleeve and a snap device 47 shown in more details in Fig. 9 allows the intended reticule pattern to be placed opposite said hole 46. The snap device 47 comprises a spring-loaded 49 ball 48 which engages recesses 50 in the sleeve 40. Finally, the semitransparent mirror can be replaced by a holographic optical element. A holographic optical element consists of a photographic film having a photographically active gelatine layer positioned on a substrate or plastic film. In order to rigidify the element, it is placed between two rigid plastic discs. Thus, the element is thin and have parallel surfaces. The holographic optical element manipulates or diffracts light of a certain specific wavelength but does not influence on light of a different wavelength which passes straight through the optical element. The light of said specific wavelength is manipulated in different ways and all commonly known optical elements, such as lenses, prisms, etc., as well as new elements can be obtained. For the purpose of this invention it is possible to construct a holographic optical element with the property to reflect incident red light as a concave mirror. Simultaneously, all other wavelengths are unaffected which means that more than 90 % of the aiming area light is transmitted. Thus, the holographic optical element can reflect 90 % of the red light while transmitting 90 % of all other light. Fig. 10 shows such a holographic optical element 63 which reflects the red light beams 60 from the reticule 61 as a concave mirror but transmits light beams 62 from the aiming area. The holographic optical element is very thin and is perpendicular to the beams 62. The holographic optical element can be arranged as a lens 64 which acts upon the red beams 65 from the red reticule. There is another holographic optical element 66 which acts as a variable prism and essentially mirrors the red beams 66 in a mirror surface 67 perpendicular to the holographic optical element 70. Such a holographic optical element can be made to act in one direction or in two directions. Such a holographic optical element is suitable for adjusting the red beams as illustrated in Fig. 13. The holographic optical element 64 of Fig. 11 has been misaligned and the parallel beams 69 have to be redirected with the holographic optical element 70 according to Fig. 12. The holographic optical element 70 can be adjustable around an axis 71 as shown by arrows 72 in Fig. 13. In order to redirect the beams 71 in the perpendicular direction, the same holographic optical element 70 can be adjusted as indicated by arrows 73. Alternatively a second holographic optical element 70 can be used. Thus, according to the invention, the holographic optical element can replace the mirror in order to make the sight more efficient. Also the new holographic optical element 64 can replace the mirror but it can now hardly be called a reflecting sight. For conveniency this feature is intended to be incorporated in the present invention for a reflecting sight, since the principle and assembly of the sight is the same as for a reflecting sight, although the reticule now can be placed at the forward end of the sight. Of course the different elements of Figs. 10 to 13 can be combined in order to achieve the necessary adjustment possibilities as intended. In the above a preferred embodiment of the invention has been disclosed by reference to the appended drawings for the purpose of examplifying the invention. However, it is obvious to a skilled person that the embodiment described can be modified in many respects within the scope of the invention. The invention is only limited by the appended patent claims.

Claims: CLAIMS 1. Sight intended to be attached to a hand fire arm or similar comprising a sight tube (2), one or several optical elements, such as a semitransparent, concave mirror (8) arranged in the tube, a reticule (31) positioned in the focal plane of the optical element, an illumination device (36) for the reticle, and a positioning device (11, 20), characterized in that the optical element (8) is thin and is made of a plastic material. 2. Sight as claimed in claim 1, characterized in that the tube (2) is adapted to be attached directly to the hand fire arm without any intervenient positioning means and that said positioning device (11, 20) is adapted inside the tube in order to adjust the optical element. 3. Sight as claimed in claim 2, characterized in that the tube (2) and the positioning device (11, 20) is made of molded plastic. 4. Sight as claimed in claims 2, 3 or 4, characterized in that the positioning means comprises a first positioning arm (11) for horizontal angle adjustment of the optical element, and a second positioning arm (20) for vertical angle adjustment of the optical element, the positioning arms being pivotable around supporting points (12, 21, respectively), and each positioning arm being divided in a front portion and a back portion (13, 14 and 22, 23, respectively), and the front portion (13, 22) cooperating with the optical element (8) while the back portion (14, 23) comprises a threaded hole (15, 24) in which a screw (16, 27) provided with a head (17, 28) cooperates for adjustment of each positioning arm, and the screw (16, 27) of each positioning arm (11, 20) being provided with a portion with teeth (29), which cooperate with snap devices (30), thereby quantisizing the rotation of the screws. 5. Sight as claimed in claim 4, characterized in that the first positioning arm comprises a spring (18) which biases the positioning arm and the screw (16) such that the head (17) of the screw abuts the tube (2), and comprises, at its front portion (13), a craddle (9) which is horizontally pivotable around supporting points (10) and is biased by means of a spring (19) against the second positioning arm, the craddle (9) supporting the optical element (8) and being adjustable by the second positioning arm (20) against the action of said spring (19) for vertical angle positioning of the craddle (9) and thus the optical element (8). 6. Sight as claimed in anyone of the previous claims, characterized in that the reticule (3) is cross-hairs, a triangle, a graduated scale or similar positioned in the focal plane of the optical element (8), and that the reticule (31) and the illumination device (36) are adapted in an insert (33), which is positioned in a recess (34) of the enclosure and is retained by means of a locking plate (35), whereby the insert is exchangabl e. 7. Sight as claimed in claim 6, characterized in that the illumination device (35) consists of a plane parallel rod (37) made of a plastic material having a fluorescent material embedded therein, the plastic rod comprising side surfaces and two edge surfaces being perpendicular to the side surfaces, the first edge surface being positioned close to the reticule (31) in order to illuminate it. 8. Sight as claimed in anyone of claims 1-5, characterized in that the reticule is a sleeve (40) which is rotatably arranged in a recess in the tube (2) and comprises several reticule patterns at one of its edge surfaces to be positioned opposite a hole (42) in the tube by rotation of the sleeve. 9. Sight as claimed in anyone of the previous claims, characterized in that the optical element is a semitransparent mirror made of a thin spherical disc of equal thickness covered with a semitransparent or semireflecting layer, such as a gold layer or an aluminum layer. 10. Sight as claimed in anyone of claims 1-8, characterized in that the optical element is one or several holographic optical elements having the property of affecting only light beams of a certain predetermined wavelength, all other wavelength passing essentially unaffected, the holographic optical element being a concave mirror, a lens or a variable or fixed prism or combinations thereof.

Inventors: RUDER, NILS INGE ALGOT, Rüder, Nils Inge Algot
Applicants: RUDER, NILS INGE ALGOT
Application year: 1983
Main classification: F41G1
IPC codes: G02B23, F41G1