Flashlight with switch assembly
BACKGROUND 
     Nelson U.S. Pat. No. 4,398,238 describes an adjustable focus flashlight having a reflector mounted in the head, in which the focus is adjusted by turning the head on the flashlight body, as is well-known in the art. Nelson shows a switch module in the body which holds the bulb. He teaches retaining the focus adjustment with a helical spring disposed partly in the flashlight body and partly within the head. One end of the spring is seated on the outer, or rearward, surface of the reflector, and the other flat end is seated on the switch module. As Nelson points out, the seat on the switch module is flat and relatively slick, so the spring can easily rotate with respect to the module as the head is turned. If this were not so, according to Nelson, the spring might be more effective than desired in retaining the position of the head, and could even prevent a desired focus of the flashlight beam from being accomplished. Alternatively, Nelson points out, if twisting the head were accompanied by twisting of the spring, then the spring would tend to return to its initial position rather than retaining it in the desired position of adjustment. Obviously, then, using the seat on the switch module to support the spring prevents the storage of a spare bulb near the end of the module. 
     My invention, on the other hand, eliminates the spring, and provides an easily accessible spare bulb near the end of the switch module. Instead of the spring, I provide a replaceable switch unit threadably connected to the head and the battery unit, said unit having an O-ring that frictionally engages part of the head, to retain the focus adjustment. 
     SUMMARY 
     This invention relates to an adjustable-focus flashlight consisting of a head, a replaceable switch unit, and a battery unit. 
     An object of the invention is to provide a flashlight of this type having a readily accessible spare bulb holder, located in a switch assembly, in the switch unit, near the bulb in use, for quick replacement thereof in case of failure. 
     Another object of the invention is to provide a flashlight of this type with a novel means for adjusting, and retaining, the focus, said means comprising a switch unit having a cylindrical member around the switch assembly, and a flexible sleeve around the outer surface of the cylindrical member, with an O-ring formed in the end thereof, to engage a part of the head threadably attached to the cylindrical member. 
     The foregoing, and other, objects and advantages will appear from the following drawings and description. 
    
    
     DRAWINGS 
     FIG. 1 is a perspective view of a flashlight in accordance with the preferred form of my invention; 
     FIG. 2 is a longitudinal cross-sectional view of FIG. 1. 
     FIG. 3 is an exploded view of FIG. 1. 
     FIG. 4 is an enlarged, perspective view of the switch assembly, showing the means for storing a spare bulb; and 
     FIG. 5 is another enlarged, perspective view of the switch assembly, partially broken-away. 
    
    
     DESCRIPTION 
     Referring to FIG. 1 the flashlight 1 comprises a head 2, a replaceable switch unit 3, and a battery unit 4. 
     As best shown in FIG. 2, the head 2 includes a lens 5, mounted in a recess 6, in one end of the head, and a reflector 7, having a flange 8, mounted in a recess 9. A resilient ring 10 is located between the lens 5 and the flange 8. The other end of the head has internal threads 11, and an unthreaded portion 12, of slightly larger diameter, extending rearwardly. 
     A switch assembly 13, best shown in FIG. 5, comprises a switch body 14 having a top wall, a bottom wall, two side walls and two ends, with a cavity 15 therein. A first hole 16, for receiving a bulb lead, in the first end 17 of the body 14, communicates with the cavity 15. A second hole 18, for receiving a bulb lead, is also located in first end 17 of the body 14. A first opening 19, located in the second end 20 of the body 14, communicates with the cavity 15, and a second opening 21, in the body 14, communicates with the second hole 18. A spring-biased switch member 22, located in the cavity 15, has an actuating member 23, and a pair of terminals 24, 25. The first terminal 24 extends into the first hole 16, and is crimped at the end to retain the bulb lead. The other terminal 25 extends into the first opening 19. A spring contact 26, adjacent the second end 20 of the body 13, is connected to the second terminal 25. Depressing the actuating member 23 connects the terminals 24, 25, thereby connecting the spring contact 26 with the interior of the hole 16. A conductor 27, located in the second opening 21, and in the second hole 18, is also crimped at one end to retain the bulb lead. A spring contact 28, adjacent the second opening 21, is connected to the conductor 27. As best shown in FIG. 4, a pair of flexible members 29, 30, in an opening 31, in the first end 17, of the body 14, engage the opposite sides of a spare bulb (not shown). 
     Referring to FIGS. 2 and 3, the switch assembly 13 is surrounded by a cylindrical member 33, which engages the spring contact 28. The switch assembly 13 is fastened inside the member 33 by glue, or other conventional means. The cylindrical member 33 has an opening 34, for the actuating member 23, and has external threads 35 at one end, to engage the internal threads 11 of the head. The other end of the cylindrical 33 also has external threads 36, to engage the internal threads 37 of the battery unit 4. 
     A flexible sleeve 38, of rubber, for example, surrounds the outer surface of the cylindrical member 33, and has a circular protrusion 39 at the end. The circular protrusion frictionally engages the unthreaded portion 12 of the head 2, to restrain rotation of the head 12, and maintain the focus adjustment. Therefore, the switch assembly 13, the cylindrical member 33, and the flexible sleeve 38 form an easily replaceable switch unit 3. 
     While I have described the best mode of carrying out my invention, it will be obvious to those killed in the art that many variations may be made in the exact construction shown without departing from the spirit and scope of the invention.