US3904867A

US3904867A - Flashlight with semi-transparent lens

Info

Publication number: US3904867A
Application number: US457894A
Authority: US
Inventors: Kenneth G Salem
Original assignee: Individual
Current assignee: Individual
Priority date: 1974-04-04
Filing date: 1974-04-04
Publication date: 1975-09-09
Anticipated expiration: 1992-09-09

Abstract

A flashlight is provided with a Semi-Transparent Lens of nonglare etched glass in order that the light penetrating such lens will be softly diffused and will result in a uniform spot of light which is essentially free of multiple images in the center of the beam of light forming said spot.

Description

I Umted States Patent 11 1 1111 3,904,867 Salem Sept. 9, 1975 [54] FLASHLIGHT WITI-I SEMI-TRANSPARENT 2,848,601 8/1958 Beach 240/ 106.1 LENS FOREIGN PATENTS OR APPLICATIONS [76] Invent Kenneth Salem Belmont 839,084 6/1960 United Kingdom 240/10.6 so Jdmswwni 15904 559,098 6/1958 Canada 240 l0.6 SD [22] Filed: Apr. 4, 1974 [21] AppL No; 457,894 Primary Examiner-Joseph F. Peters, Jr.

[52] US. Cl... 240/10.6 R; 240/l0.6 SD 240/10.66; ABSTRACT 2 240/413; 240/ 106'] A flashlight is provided with a Semi-Transparent Lens lift. CI. FZIL 15/00 of non glare etched glass in order that the light p [581 meld Search trating such lens will be softly diffused and will result 240/106, in a uniform spot of light which is essentially free of multiple images in the center of the beam of light [5 6] References Cited forming Said Spot UNITED STATES PATENTS 2,333,541 11/1943 Madan 240/10.6 s1) 1 Clam, 3 D'awmg I I I FLASHLEGHT WETH SEMI-TRANSPARENT LENS This invention relates to hand held flashlights; searchlights; lanterns and the like, all of which are of a type of construction in which various size dry cell batteries are utilized as the source of power in conjunction with a highly polished smooth mirror-like reflector and a lamp bulb.

At present, all such lights on the market are fitted with a transparent lens, either of a glass or plastic material. The purpose of the transparent lens is to protect the highly polished smooth mirror-like finish of the reflector which is an important element for obtaining maximum intensity of light. Without the lens, the reflector would eventually lose its mirror-like finish due to the deposition of dust and the like, thereby resulting in a reduction of light intensity. The lens also serves to protect the lamp bulb from breakage, and likewise, as in the case of the reflector, to protect the bulb from dust and dirt or the like depositing on same.

The mechanics of flashlights or the like, as is well known, is simply to supply power to a lamp bulb which is generally constructed with a tungsten filament. The dry cell type batteries, with the switch in the on posi tion, causes the filament to heat up to such an extent that it glows white-hot. The smooth mirror-like finish of the reflector creates a multiplicity of images of the white-hot filament, and as a result of this action, the light which impinges upon any opaque surface is made up of a large number of these filament images. Since a highly polished smooth mirror-like reflector is not at all a perfect diffuser, the resultant light which is emitted is very uneven. The surface upon which the light impinges shows the main spot of light and the surrounding light to be full of shadows, and as a whole, is irregular in shape.

The problem of shadows and non-uniform distribution of light issuing from flashlights has always been a problem. In recent years however, some manufacturers of flashlights have remedied a substantial part of this problem by fitting their flashlights with a reflector having a somewhat orange-peel like surface in order to diffuse the light which issues from same. As a result, a substantial reduction in the irregular and shadow-like effeet is accomplished. However, since the reflector has this so-called orange-peel like surface, a substantial re duction of reflectivity is lost since the very smooth mirror-like finish is not present in this type of reflector. This in turn reduces the intensity, or brightness of the light impinging upon a surface.

To my knowledge, at present, this is the most significant advance made to improve upon the quality of light issuing from a flashlight or the like.

I have invented a flashlight in which the shape of the main spot oflight is perfectly round; is larger in diameter; in some cases and most significantly, its greatest advantage being that the light issuing from it and impinging upon a surface is very close to being 100 percent uniform in distribution. In other words, the light is diffused to such a high degree that shadows are nonexistent and loss of intensity in light is almost nil.

Preferrably, this particular apparatus comprises a translucent, or otherwise, a semi-transparent lens fitted to any type of flashlight, Searchlight, lantern or the like having a highly polished smooth mirror-like reflector. This semi-transparent or translucent lens is sometimes referred to as smoked glass or, more preferrably as non-glare glass, having at least one surface etched. It is popularly used in picture frames to do away with glare.- One popular brand name of this type of glass is called Trusite which is widely used in picture frames. l have found this particular type of non-glare, etched glass to be ideal as a lens material for eradicating the shadows and improving upon the quality of lightissuing from flashlights. Other brand names of this type glass, which is commonly etched on both surfaces would give the same fine results, however, quality varies with refractive index.

In the foregoing general description of my invention I have set out certain objects; purposes and advantages. These objects, purposes and advantages will be apparent from a consideration of the following description and accompanying drawings, in which:

FIG. 1 is a sectional view of the lamp end of an ordinary flashlight embodying the principles of the present invention.

FIG. 2 is a top plan view showing the lamp end of the flashlight without the improved lens or as it would otherwise appear with a transparent lens.

FIG. 3 is a top plan view showing the lamp end of the flashlight embodying the principle of the present invention.

Referring to the drawing, a non-glare etched glass lens 10 is shown as applied to a flashlight 11 which is depicted in the drawing only at the lamp end. The lens 10 has at least one etched surface 10a. The reflector body 12 is constructed in a manner such that the flashlight bulb 13 is centrally positioned for appropriate transmission of light. In actual operation; when the flashlight bulb 13 is energized, a multiplicity of images of the filament 14 is transmitted by means of the reflector 15. When the reflector 15 has a smooth, highly polished mirror-like finish, as with most flashlights, the

glowing hot filament 14 is reflected from essentially every angle of such reflector 15 and transmitted in enlarged form, thereby creating a spot of light consisting of a large number of overlapping and enlarged images of the glowing filament 14. This, essentially, is the .cause of the so-called dark spots or shadows so inherent with flashlights or the like. A highly polished, smooth mirror-like reflector is the most efficient means for attaining maximum transmission of light from flashlights. ln order to retain maximum transmission of light from flashlights, the reflectors mirror-like finish must be protected, and of course, the flashlight bulb must be protected from dirt and breakage. As a result, a bulb and reflector protector, commonly referred to as a lens, is ordinarily found on flashlights. Flashlights designed to transmit a spot of light with maximum brightness are commonly fitted with a fully transparent planar glass or plastic lens. ln the drawing, it is attempted to show that the new improved lens 10 is semi-transparent. lts construction is of a planar, non-glare glass having at least one etched surface 10a to diffuse the light issuing from said reflector 15, thereby creating a softly diffused shadow free light which is essentially free of the enlarged and multiple filament images in the center of the beam of light forming the spot. By utilizing this type of lens 10 having at least one etched surface 10a, it will serve as an efficient diffuser of light in addition to its function as a bulb and reflector protector. With this particular type of non-glare etched glass lens 10, a I

open end and a smaller opposite open end and adapted to receive a flashlight bulb therein for projection of light from said bulb through the large open endiof said reflector and forming a spot light beam, the large open end of said reflector being completely closed by a planar non-glare glass lens having at least one surface thereof etched to diffuse the light issuing from said reflector large open end, thereby creating a softly diffused shadow-free light which is essentially free of multiple images in the center of the beam of light forming said spot.

Claims

1. A flashlight having a smooth highly polished reflector at one end thereof, said reflector having a large open end and a smaller opposite open end and adapted to receive a flashlight bulb therein for projection of light from said bulb through the large open end of said reflector and forming a spot light beam, the large open end of said reflector being completely closed by a planar non-glare glass lens having at least one surface thereof etched to diffuse the light issuing from said reflector large open end, thereby creating a softly diffused shadow-free light which is essentially free of multiple images in the center of the beam of light forming said spot.