Flashlight With Focusing Beam Assembly

The present invention relates to the construction of flashlights and, more particularly, to a mechanism for allowing adjustment of the beam width provided by the flashlight.

U.S. Pat. Nos. 4,658,336 and 4,577,263 both describe a flashlight having a beam which adjusts by twisting a face cap at the forward end of the flashlight. Although generally functional, the design of the flashlights suffers from certain disadvantages. The receptacle holding the light bulb at the front of the flashlight is not removable, requiring that a separate end cap be provided for replacing batteries. Such a design is more expensive to fabricate and requires an additional seal in immersible units. Additionally, the receptacle holding the light bulb in the flashlight is not replaceable, complicating the repair should the focusing beam mechanism be damaged. Also, in the event of failure, the fragile light bulb must be separately replaced as it is part of no larger replacement unit. Finally, if the face cap is removed from the flashlight, the light bulb is exposed and subject to breakage.

Tekna, Redwood City, CA, sells a product line of miniature flashlight identified as the Tekna Lite.TM. 2, Micro-Lite.TM., and Mono-Lith.TM., which consists of a flashlight casing, a beam assembly, and a lens cowling which attaches to the forward end of the casing, urging the beam assembly against the batteries therein. The flashlight operates by urging the beam assembly rearward against a pair of fixed conductors axially aligned within the casing. When a conductive ring on the back of the beam assembly is brought into contact with the conductors, the light bulb in the beam assembly is energized. The parabolic reflector and light bulb within the beam assembly, however, are positionally fixed relative to one another, and no provision is made for beam width adjustment.

It would be desirable to provide a flashlight construction having a focusing beam mechanism, where the focusing beam mechanism can be completely removed from the forward end of the flashlight casing to allow for battery replacement. Such a construction eliminates the need for a detachable rear cap, reducing the number of seals required to provide an immersible unit. It would be further desirable that the focusing beam assembly be provided in a self-contained unit which would allow for replacement of the unit should a failure occur in the focusing beam mechanism. Such a construction would also eliminate the need for separately replacing fragile flashlight bulbs and would greatly limit the exposure of such bulbs to breakage when the flashlight unit is partially disassembled. Such a self-contained focusing beam assembly would also allow replacement of fixed beam assemblies in previously constructed flashlights when it is desired to add a focusing beam capability. It would further allow the user the option of selecting a fixed beam assembly or a focusing beam assembly as desired.

According to the present invention, a flashlight includes a focusing beam assembly capable of selectively adjusting the beam width. Usually, the focusing beam assembly will be an integral unit capable of being completely removed from the remainder of the flashlight and replaced or interchanged with a non-focusing beam assembly. In this way, there is no need to provide a separate detachable end cap on the flashlight for battery replacement, and the focusing beam assembly may be easily removed and replaced in the event the assembly or the light bulb fails.

The flashlight includes an elongate casing which holds one or more batteries in series therein. A spring disposed at the rear of the casing urges the batteries in the forward direction. At the front of the flashlight, a parabolic reflector capable of axial translation circumscribes a light bulb. The light bulb contacts one pole of the batteries and moves with them at all times. The parabolic reflector moves separately from the light bulb, and a second spring biases the parabolic reflector in the forward direction relative to the light bulb in the batteries. A lens cowl is placed over the forward end of the casing and engages the parabolic reflector. By screwing in the lens cowl in the rearward direction, the parabolic reflector is urged rearward. Initially, the rearward motion is transmitted through the reflector spring to the light bulbs and batteries. Thus, the reflector, light bulb, and batteries move rearward in unison until a conductor coupled to the light bulb engages a battery contact fixed to the casing. The contact completes the circuit to the light bulb and prevents further motion of the light bulb and batteries. The reflector, however, is able to continue moving rearward, thus affecting beam width adjustment as the light bulb moves relative to the focus of the parabolic reflector.

In the preferred embodiment, the parabolic reflector, light bulb, and reflector spring are included in a focusing beam assembly further comprising a base which carries the electrical connector. The light bulb is fixed at the base and receives one end of the spring, the other end of which urges the parabolic reflector away from the base. Thus, even when the conductor on the base contacts the fixed electrical contact, the parabolic reflector is able to continue rearward movement by compressing the reflector spring. Such a self-contained focusing beam assembly provides all of the advantages discussed above.

FIG. 1 illustrates the prior art fixed beam assembly used in the Tekna Lite 2, described above.

FIG. 2 is a perspective view of a flashlight constructed in accordance with the principles of the present invention.

FIG. 3 is an exploded view of the flashlight of FIG. 2.

FIGS. 4A-4C illustrate the operation of the flashlight of FIG. 2, with FIG. 4A showing the flashlight in an off (unenergized) configuration, FIG. 4B illustrating the flashlight in an on (energized) configuration with a first beam focused, and FIG. 4C illustrating the flashlight in the on (energized) configuration in a second beam focus configuration.

Referring to FIG. 1, a fixed beam assembly 10 of the type employed in the Tekna Lite 2, described hereinabove, includes a parabolic reflector unit 12 including the reflector 14 and a shank portion 16. A pair of flanges 18 and 20 are provided on the flank, and a conductor ring 22 is provided on a rear face of the second flange 20. A light bulb 24 is threadably received in the shank portion 16 and includes a terminal 26 projecting rearward beyond the second flange 20. The conductor ring 22 is electrically coupled to the second terminal 28 of the light bulb which is received in the shank 16. As can be seen, once the light bulb 24 is screwed into place, the light bulb is incapable of movement relative to the reflector 14.

Referring now to FIGS. 2 and 3, a flashlight 30 includes an elongate casing 32, a lens cowl 34, and a focusing beam assembly 36 (shown in an exploded view in FIG. 3). The elongate casing 32 defines an internal axial chamber 38 having a battery spring 40 at its rearward (to the right in FIG. 3) end. The battery spring 40 is electrically coupled to a pair of rigid electrical conductors which extend from the rear end of the casing 32 to a termination point 44 proximate open forward end 50 of the casing. The axial chamber 38 is adapted to receive one or more batteries 52 (with two being illustrated) held in series with one pole (marked -) of the battery being in contact with battery spring 40. In this way, contact with that battery pole may be achieved through the termination ends of conductors 42. The other battery pole (marked +) is located at the forward end of the casing at approximately the termination location 44.

Lens cowl 34 includes a transparent lens element 60 and a cylindrical skirt 62. A threaded portion 64 of the interior surface of skirt 62 mates with threaded portion 66 on the outside of the forward end of casing 32. A smooth portion 68 on the interior surface of skirt 62 will engage an O-ring seal 70 on the casing 32. Thus, the lens cowl 34 may be threaded onto the casing 32 with a water-proof seal being provided by the O-ring 70. The seal will remain water tight while the lens cowl 34 may be axially adjusted by turning relative to the casing 32.

The focusing beam assembly 36 includes a base element 80 having a plurality of hooks 82 extending from its periphery. Parabolic reflector 84 includes a flange 86 and rear shank 88. The flange is received within hooks 82 on base 80 and the shank is shorter than the length of hooks 82. Thus, the reflector 84 may move axially within the base with one limit of travel being provided by the hooks 82 and the other limit of travel being provided when the shank 88 engages the rear or bottom surface 90 of the base 80. A reflector spring 92 will be disposed between the rear surface 90 of the base 80 and the flange 86. In this way, the reflector 84 is normally in its forward or extended position relative to the base, unless a force is applied on the reflector to compress the spring 92. Light bulb 94 is threadably received in an aperture 96 in the base 80. A conductor ring 98 is provided about the periphery of the base and is electrically coupled to the side pole of light 94.

Referring now to FIGS. 4A-4C, the operation of the flashlight of the present invention will be described. In FIG. 4A, cowling 34 is disposed generally in the forward or rightward direction relative to casing 32. The focusing beam assembly 36 is also urged in the forward direction by contact with batteries 52, which in turn are being urged forward by battery spring 40. The parabolic reflector 84 is also in the extended or forward configuration relative to base 80 because the reflector spring 92 has a greater spring constant than the battery spring 40. The light bulb 94 will not be energized in this configuration. Although the battery pin is in contact with the positive (+) terminal of the batteries, the side terminal of the light is disconnected. That is, conductor ring 98 is out of contact with the rigid conductors 42. In this configuration, the filament of the light bulb 94 is disposed behind (toward the bottom of the flashlight) the focus F of the parabolic reflector.

Referring now to FIG. 4B, the flashlight may be turned on by twisting lens cowl 34 so that the lens cowl is moved in the rearward or leftward direction. Movement of the lens cowl 34 urges the focusing beam assembly 36 in the rearward direction, resulting in the compression of battery spring 40. Such motion continues until the conductor plate 98 on base unit 80 engages the terminals of conductors 42, as illustrated in FIG. 4B. The light will then be turned on with the reflector 84 still in its fully extended, forward configuration. The filament of bulb 94 remains to the rear of focus F, just as in the off configuration of FIG. 4A.

Referring now to FIG. 4C, further turning will cause the lens cowl 34 to move additionally in the rearward direction. As movement of the base unit 80 is now prevented by the rigid conductors 42, the force against reflector 84 will compress the reflector spring 90. Moreover, as the light bulb 94 is positionally fixed relative to the base unit 80 and batteries 52, so that the reflector 84 will move relative to the light bulb 94. In this way, the filament of the light bulb 94 moves relative to the focus F of the parabolic reflector 84, changing the beam width which is generated. Specifically, the filament moves from a rearward orientation (as illustrated in FIGS. 4A and 4B), through the focus F (not illustrated), to a position forward of the focus (as illustrated in FIG. 4B). The beam will be at its narrowest when the filament is closest to the focus F, and will diverge as the filament is moved away from the focus in either direction. Thus, the beam width may be adjusted by moving the lens cowl 34 in the forward and rearward directions. Also, the flashlight may be turned off by moving the lens cowl 34 sufficiently in the forward direction so that contact between conductor ring 98 and rigid conductors 42 is broken.

Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it will be obvious that certain changes and modifications may be practiced within the scope of the appended claims.