Patent Abstract:
A combination lock dial and ring assembly for combination locks and the like for limited range top reading of the dial indicia by reflected light rays only, including a rotatable dial member having a circular dial portion and a knob formation projecting forwardly therefrom wherein the dial portion has a rearwardly facing annular indicia bearing surface adjacent its periphery provided with rearwardly facing dial graduations and mirror image reversed dial numerals thereon for reading along reflected light ray paths. The dial ring has a forwardly facing dial receiving cavity encircled by an integral shielding surround ring formation over a sufficient extent to exclude observation of the dial graduations and numerals laterally and below the dial portion and having an interruption of limited circumferential extent providing a sight opening for observation of the dial graduations and numerals in a restricted observation zone generally above and vertically aligned with the axis of the dial member. The surface of the dial receiving cavity rearwardly adjacent the dial has an arcuate light-reflecting mirror surface at least spanning the arcuate extent of said sight opening positioned to reflect light rays from said dial graduations and numerals along reflection ray paths extending along upwardly and forwardly inclined paths to the restricted observation zone.

Full Description:
BACKGROUND AND OBJECTS OF THE INVENTION 
     The present invention relates in general to combination locks, and more particularly to view limiting dial and dial ring assemblies for combination locks to afford security against unauthorized observation of the combination being dialed when opening the lock. 
     It has long been recognized that the dialing combination for combination locks are subject to theft by unauthorized viewing of the successive registrations of dial markings occurring during opening of the lock. Where such a lock is opened in the presence of other persons, it is a simple matter for each persons to note the combination from a point to the side of or at angles to the rear or over the shoulder of the operator and thereby gain unauthorized access to the vault, safe or other security receptacle protected by the lock. Even where some restriction of the field of view is achieved, persons do not have to see the entire combination dialed at one time, but can learn one number each time the unauthorized observer is able to look at the dial when the combination is being dialed by an authorized person, and thus over a short period of time acquire knowledge of the dialling combination without arousing suspicion of the authorized person opening the safe. Ideally, the dial should expose the indicia or numbers of the combination actually being run only to the authorized operator and not anyone standing elsewhere. 
     Heretofore, various expedients have been proposed for use in connection with conventional combination lock dials, which shield the greater portion of the dial from view by unauthorized persons. These have generally taken the form of a shield or cover provided with a window exposing only a limited number of the dial markings to view, either from a direction forwardly of the dial, or in some cases from a direction above the dial where the dial markings and numerals are merely provided on a peripheral cylindrical flange surface of the dial. Such dial shields have the dual purpose of tempering observation of the dial numbers by possible surreptitious observance to either side of the operator while the operator is dialing the combination, and limiting the range of exposed dial markings which are visible so that the body of the operator will shield the exposed dial area from observation by persons at remote locations or to the side of the operator. Earlier U.S. Pat. Nos. 2,728,215 to Bremer, 2,858,692 to Deaton et al, and 2,836,052 to Harry C. Miller, one of the joint inventors of this application, are typical of such prior structures. Such prior art dial shields, however, were usually in the form of additional accessories which must be associated with the combination lock and dial, and in many cases afford such a limited visible dial area that the lock dial must be operated very slowly in order to bring the proper numbers on the dial into registry with the index, zero or reference mark. Also because of the restricted visible dial area, the numbers are often so obscure or difficult to count that the operator must make a number of attempts before the successful combination is dialed. U.S. Pat. No. 2,690,664 to Harry C. Miller, and U.S. Pat. No. 4,197,726 to Uyeda are examples of combination lock dial and ring assemblies having a limited range of visibility forwardly of the dial, also for the purpose of reducing the chance of unauthorized viewing of the combination while it is being dialed by an authorized operator. 
     An object of the present invention is to provide a view limiting dial and dial ring assembly for combination locks and the like adapted to be mounted on vertical safe doors or similar vertical surfaces, which more severely limits the angular range of viewing positions in reflected light ray paths from which an authorized operator can dial the combination of the associated combination lock mechansim, further reducing the chance of unauthorized observation of the lock combination when being dialed. 
     Another object of the present invention is the provision of a novel view limiting dial and dial ring assembly for combination locks and the like as described in the preceding paragraph, wherein the numeral markings on the dial are provided on the rearwardly facing surface of the dial as mirror image numerals of normal dial marking numerals and are observable only by reflection from a reflective mirror surface rearwardly confronting the marked dial portion observable from a highly restricted range of observation points to the front and above the dial. 
     Another object of the present invention is the provision of a novel and ring assembly for combination locks and the like as described in the two immediately preceding paragraphs, wherein the index, zero or reference mark for the dial is provided as an opaque thin planiform vane member intercepting observation of portions of the forwardly visible dial markings from side locations. 
     Another object of the present invention is the provision of a novel dial and dial ring assembly for combination locks useable in view limiting installations as described in the preceding paragraphs and also interchangeable with members to provide restricted forward viewing of the dial without using reflective ray paths to observe dial markings. 
     Other objects, advantages and capabilities of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings illustrating preferred embodments of the invention. 
    
    
     DETAILED DESCRIPTION OF THE FIGURES 
     FIG. 1 is an exploded perspective view of a combination lock dial and ring assembly embodying the present invention; 
     FIG. 2 is a front elevation view thereof; 
     FIG. 3 is a vertical section view of the dial and ring assembly, taken along the line 3--3 of FIG. 2; 
     FIG. 4 is a detailed section view, to enlarged scale, taken along the line 4--4 of FIG. 2, showing reflecting light ray paths in broken lines; 
     FIG. 5 is a rear elevation view of the combination lock dial and knob component, viewed from the line 5--5 of FIG. 3; 
     FIG. 6 is an exploded perspective view of a further embodiment employing the dial and knob of the previously described embodiment but with a different dial ring and shield structure for forward viewing applications; 
     FIG. 7 is a front elevation view of the embodiment of FIG. 6; and 
     FIG. 8 is a vertical section view, taken along the line 8--8 of FIG. 7. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring to the drawings, wherein like reference characters designate corresponding parts throughout the several figures, and particularly to the embodiment shown in FIGS. 1 through 5 directed to the laterally shielded top reading version providing severely restricted viewing along only reflected light ray paths shown in FIGS. 1 through 5, the combination lock dial assembly, indicated generally by the reference character 10, is adapted to be mounted on the front face of a wall member 11 such as a safe door, a file cabinet drawer wall, or similar security closure, in the conventional manner, and to be secured to the lock mechanism operating spindle 12 projecting forwardly from the combination lock case or housing 13 through a hole in the wall member 11. The combination lock case 13 and the lock mechanism components are secured to the wall member 11 in the usual manner, as by screws extending forwardly through corner holes in the lock case, and the lock case 13 and lock mechanism components may be of any conventional form, such as disclosed in earlier U.S. Pat. No. 2,575,674 issued Nov. 30, 1951 or U.S. Pat. No. 3,339,383 issued Sept. 5, 1967 both granted to Harry C. Miller, one of the co-inventors herein. 
     The dial assembly 10 of the embodiment illustrated in FIGS. 1-5 includes an integral dial and knob member 15 having a knurled surface, substantially truncated conical or cylindrical knob formation 16 of a selected diameter, for example about 2&#34;, projecting, in one illustrative example, about 5/8&#34; forwardly from a larger diameter tapered disc dial portion 17, in the preferred embodiment, which extends in the illustrative embodiment to a diameter of about 3&#34; and has outwardly convergent symmetrically or tapered front and rear annular rear dial faces 18,19 of isosceles triangular radial cross-section in radial section planes which include the center axis of the dial and knob member, converging to a very narrow cylindrical peripheral surface 20 which may be about 1/16&#34; wide. In the illustrated embodiment, the dial and knob member casting 15 has a flat annular planiform rear face 21 which is parallel to the plane perpendicular to the center axis of the dial and knob member 15 and spindle 12 having an outer diameter substantially corresponding to the outer diameter of the knob formation 16, from which projects a rearwardly extending cylindrical boss 22 having an internally threaded center bore 23 into which the forward end of the spindle 12 is threaded or otherwise assembled to assemble the dial and knob member 15 on the spindle 12. 
     The annular outwardly convergent inclined or tapered front and rear dial faces 18,19 are provided adjacent the periphery or rim 20 of the dial with etched or otherwise indented or formed radial indicia lines or graduations 24 forming the usual dial markings, and is also provided with numeral indicia 25, customarily adjacent each 10th dial graduation 24. 
     An important feature of the present invention, however, is the fact that the numerical or numeral indicia 25a on the rear dial face 19 of the dial and knob member 15 are mirror images of the numerals represented thereby when directly observed, as is shown in FIGS. 3 and 5. In the illustrated embodiment, the dial graduations 24 on the rear dial face 19 are in precise radial alignment with the corresponding dial graduations 24 on the front dial face 18, and the mirror image versions 25a of the decade numerals 0 through 90 on the rear dial face 19 register radially with the corresponding directly readable decade numerals 25b on the front dial face 18. Also, in the illustrated embodiment of the invention, the front face or surface of the knob formation 16 of the dial and knob member 15 is recessed to accommodate a thin disc 26 to be secured therein, as by press-fitting or suitable adhesive, having its front surface textured to provide a desired ornamental appearance, for example resembling the texture of leather or ornamentally textured wall covering material. 
     In the version of the combination lock and dial assembly illustrated in FIGS. 1-5 designed for top reading severely restricted viewing along only reflected light ray paths, a dial ring 28 is provided, adapted to be fixed against the front face of the front wall member 11 by mounting screws or the like (not shown) extending through openings in the dial ring 28 behind the dial portion 17 of the dial and knob member 15, and having a center opening 29 corresponding substantially to, but slightly larger than, the diameter of the rearwardly projecting cylindrical boss 22 of the dial and knob member 15 to rotatably journal the dial and knob member 15 in the dial ring 28 concentric with a common center axis of the dial and knob member 15, the dial ring 28, and the spindle 22. The dial ring 28 is provided with a forwardly opening, generally cylindrical but circumferentially interrupted well or cavity 29 bounded outwardly by a forwardly convergent inclined or truncated conical annular surround ring 30 forming an annular cylindrical shield formation outwardly encircling the tapered disc dial formation 17 of the dial and knob member 15 and forming a sight barrier to visual observation of the dial numeral indicia 25 from positions radially or located transversely sidewise or laterally from the dial and knob member 15, except for an approximately 80° circumferential zone located vertically above the axis of the dial and knob member 15 and forwardly thereof. This restricted viewing zone is defined by the viewing interruption, gap or window opening 31 arranged symmetrically with respect to the vertical center plane through the center axis of the dial and knob member 15 and bounded by the sides or shoulders 32. 
     The bounding side wall of the surround ring encircling the forwardly facing generally cylindrical well 29 defines a cylindrical surface 33 concentric with the center axis of the dial and knob member 15 and dial ring 28 and spindle 12, and has a diameter very close to but slightly larger than the outer diameter of the tapered disc dial portion 17 to encircle and receive the tapered disc dial formation 17 nested therein as illustrated in FIG. 3. The bottom or rear wall of the well 29 forms a confronting flat or planiform annular surface 34 having an outer diameter corresponding to the diameter of the planiform or flat rear face 21 of the dial formation 17, joining an outer rearwardly inclined or tapering truncated conical rear surface portion 35 extending from the outer perimeter of the flat rear wall portion 34 of the well 28 to the cylindrical outwardly bounding side wall 33 of the well 29. 
     In the sight opening or gap portion 31 of the shielding surround 30 of the dial ring 28, the rear surface of the gap portion is formed as an arcuate rearwardly inclined annular conical surface 36 extending between the bounding sides or shoulders 32 of the interruption 31 inclined, in the illustrated embodiment, at an angle of about 40° from the vertical plane through the flat rear face of the dial ring 28. In one illustrated embodiment, the outer diameter of the dial ring 34 is about 4&#34; and its maximum thickness from the forwardmost portion of the forwardly inclined surround 30 to the flat rear or back surface of the dial ring 28 is about 3/4 of an inch. 
     To prevent observation of the dial numerals 24b on the front dial face 18 of the tapered disc dial portion 17, an uninterrupted annular front cover 37 is provided which is of forwardly convergent truncated conical or frusto-conical configuration as will be apparent from FIG. 1, having a center opening 38 of an inner diameter corresponding closely to but just larger than the maximum diameter of the knob formation 16 of the dial and knob member 15. The outer rim 39 of the front cover 37 has a diameter corresponding to the diameter of the annular rabbet or groove 40 formed in the forwardmost edge portion of the outwardly bounding cylindrical side wall 33 of the forwardly facing well 29 to be tightly fitted therein by either a press-fit or secured by suitable adhesive means or the like. While the annular front cover 37 forms a sight barrier to front reading observation of the numeral indicia 25 on the dial portion 17, severely restricted observation of a reflected image of the mirror image or reversed numerals 25a on the rear dial face 19 is permitted by providing an annular arcuate truncated conical mirror strip 42 which is affixed to and spans the arcuate portion of the outwardly encircling truncated conical rear surface portion 35a of the well 29 spanning the circumferential extent of the sight opening 31 bounded by the bounding shoulders 32 and extends a short circumferential distance beyond the shoulders 32. With this arrangement the surface of the mirror strip 42 can be viewed by the operator from a severely restricted viewing zone and see by reflected light rays reflected by the surface of the mirror strip 42 a directly readable image of the mirror image indicia 25a on the rearwardly facing dial face 19 lying within the site opening or window region 31. 
     To further restrict unauthorized observation of the dial numerals 25, the index mark or reference forming the fixed index for use in dialing the lock combination, in the preferred embodiment of the present invention, is formed by a thin opaque index vane 44 lying in a vertical plane through and including the center axis of the dial and knob member 15 and spindle 12 and dial ring 28. The rear edge of the vane 44 is of rearwardly convergent triangular configuration conforming to and secured intimately to the rearwardly convergent inclined surfaces 35 and 36 rearwardly bounding the sight opening 31. Its vertical forward edge portion 44a lies in the vertical plane perpendicular to the center axis of the dial ring 28 and located at the forwardmost edge of the outwardly and upwardly inclined surface 36, and has a rearwardly declining front edge portion 44b which declines from just above the uppermost level of the rim 20 of the tapered disc dial portion 17 to the juncture of the inclined truncated conical surface 35 with the flat annular rear wall portion 34 of the well 29. 
     With this arrangement, it will be seen that the opaque character of the index mark vane 44 forms a barrier at a wide range of lateral angles to observation of the reflected image of the numerical indicia 25a on the rear dial face 19 of the dial formation 17 lying in the portions of the gap or sight window 31 to the opposite side of the index vane 44 from the observer, and the necessity of viewing the numbers by observing the mirror images reflected from the mirror strip 42 of the mirror image in numerical indicia 25a on the rearwardly facing dial face 19 greatly restricts the range of positions from which the numbers on the dial can be observed. 
     To increase the flexibility of the dial and dial ring assembly, a different embodiment of dial ring and front cover is made available, as illustrated in FIGS. 6 to 8, wherein the same dial and knob member 15 constructed in exactly the same manner as that described in connection with the preceding embodiment, is provided, but wherein the dial ring, indicated by the reference character 50, instead of being provided with the sight opening, mirror strip and relatively deeper recessed well described in the preceding embodiment, is simply provided with a shallow forwardly facing cylindrical well 51 bounded by an uninterrupted forwardly convergent annular truncated conical surround surface 52 having a reference index marking 53 thereon vertically aligned with the center axis of the dial ring and dial and knob member, and having a change index mark 54 circumferentially spaced therefrom. The center opening 55 in the modified dial ring 50 is of smaller diameter than the center opening 29 of the previously described dial ring 28, and is merely of a diameter corresponding substantially to the diameter of the dial spindle 12 to accommodate the spindle, so that the cylindrical boss 22 of the dial and knob member 15 which surrounds the spindle abuts against the forwardly facing rear wall 51a of the modified dial ring 50. In this embodiment, designed for front reading of the dial numerals, and annular front cover ring, indicated by the reference character 56 is a forwardly convergent, annular truncated conical or frusto-conical thin shield, similar to the uninterrupted front cover shield or ring 38, having a center opening 57 similar to the center opening 38 and corresponding substantially to the maximum diameter of the knob formation 16 on the dial and knob member 15, to receive the knob formation is forwardly projecting relation therethrough, but being interrupted to provide a sight opening 58 of about 80° symmetrically centered with the index reference mark 53, bounded by the radial ends 59 of the annular cover ring 56 laterally bounding the sight opening 58. With this arrangement, the same dial and knob member 15 can be readily adapted for use either as a top reading combination lock for severely restricted viewing along reflected light ray paths only, or can be readily used where desired in less expensive forward reading combination lock installations by simply replacng the dial ring 28 and front cover 37 with the dial ring 50 and front cover 56 of the later described embodiment. 
     It will also be appreciated that in each of the two above described preferred embodiments, the dial graduation markings or lines 24 on the front dial face 18 of the dial formation 17 may be eliminated along with the directly readable dial numerals 25b if only indirect reflected light top reading combination lock dialing is desired, and the rearwardly facing reverse or mirror image numerals 25a and associated dial graduation markings 24 on the rear dial face 19 may be eliminated if only forward reading combination lock dialing is desired. 
     While but two embodiments of the invention have been particularly shown and described, it is apparent that various modifications may be made in the invention without departing from the spirit and scope thereof, and that all changes and modifications coming within the scope of the appended claims are intended to be embraced thereby.

Technology Classification (CPC): 8