US3774023A

US3774023A - Flashlight

Info

Publication number: US3774023A
Application number: US00267115A
Authority: US
Inventors: C Cobarg; R Napierski
Original assignee: Braun GmbH
Current assignee: Braun GmbH
Priority date: 1972-06-28
Filing date: 1972-06-28
Publication date: 1973-11-20
Anticipated expiration: 1990-11-20

Abstract

A pocket size flashlight comprising a reflector having at least a pair of effective reflecting regions each having a different focal length but a common focal point, a light source placed in the focal point, the reflecting regions each forming a parabolic mirror, the reflector also including non-reflecting regions, additional reflectors having a focal point and being disposed to eliminate the non-reflecting effect.

Description

United States Patent [1 1 Cobarg et al. Nov. 20, 1973 FLASHLIGHT 1,751,070 3 1930 [75] Inventors: Claus Christian Cobarg, Steinbach; Reinhard Napier-ski, Oberursel, both 3:283:142 11/1966 of Germany 3,392,277 7/1968 [73] Assignee: Braun Aktiengesellschaft, Frankfurt/Main, Germany [22] Filed: June 28, 1972 Primary Examiner-Samuel S. Matthews PP ,1 5 Assistant Examiner-Michael L. Gellner Related U08. pp i Data Attorney-Ernest F. Marmorek [63] Continuation of Ser. No. 8,161, Jan. 15, 1970,

abandoned.

[57] ABSTRACT [52] US. Cl. 240/l0.6 R, 240/10.65, 240/413,

240/4135 C, 240/103 R A pocket size flashlight comprising a reflector having Cl. at least a pair of efiective reflecting regions each hay- Field of Search 10.65, ing a different focal length but a common focal point 240/1051, 4135 R, 41-37, a light source placed in the focal point, the reflecting 41.5, 10.6 CH, 10.67, 10.66, 151, 7- 41-35 regions each forming a parabolic mirror, the reflector C, 103 R also including non-reflecting regions, additional reflectors having a focal point and being disposed to elimi- References Clted nate the non-reflecting effect.

UNITED STATES PATENTS 1,955,597 4/1934 Parent 240/413 Claims, 12 Drawing Figures A A 22 T j 23 -27 24 25 B .Z #1 T" 3 y I 37 4 2a PAIENIEUuuv 20 1915 3. 774,023

SHEET 2 BF 3 FLASHLIGIIT This is a continuation, of application Ser. No. 8,161, filed Jan. 15, 1970, now abandoned.

FIELD OF THE INVENTION The present invention relates to a flashlight of miniature size provided with a reflector for the light source. Reference is had to our U.S. Pat. No. 3,692,999, filed on Dec. 10, 1970.

BACKGROUND OF THE INVENTION The use of known parabolic mirrors in flashlights may lead to difficulties in that the lamp housing cannot provide sufficient structural depth for them if the handiness of the lamp should be of prime importance.

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide a novel reflector structure in a miniature size flashlight in which the space within the lamp is of primary importance.

In accordance with the invention a reflector structure is provided having a plurality of reflector segments with different focal lengths, which, however, have a common focal point.

Such arrangement has the advantage in that it is capable of avoiding certain structural difficulties which usually are caused by the presence of certain necessary structures, such as, switches, batteries, loading portions, etc., without adversely affecting the radiation conditions of the lamp. On the contrary, the radiation conditions are improved inasmuch as the light distributing on a radiated surface of the reflector according to the invention is more uniform than it was the case in known flashlights, while the image of the incandescent filament is formed in different sizes by the parabolic mirrors and, as a result, the so-called Weichzeichneraffect takes place.

In order that the reflector zones which lie at an unfa vorable angle of incidence should not appear as dark zones, according to the invention at least one additional reflector is provided in the unshaded radiation region of the light source. According to the invention, an additional reflector can be secured or formed on the glass cover also. For this purpose, the additional reflector can be made as an annular mirror, the reflecting surface of which is directed tangentially with respect to an imaginary parabolic surface, thereby an average light beam falling on the reflector will define the point of tangency for both surfaces.

In accordance with another aspect of the present in vention, it becomes possible to provide solar cells in the region of the reflector when then during daylight recharges the batteries of the flashlight. Such cells can be advantageously provided in the sparingly or not at all illuminated reflector surfaces. As a result, the cells can collect an amount of energy during the daylight which will last for several hours of use.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will become more readily apparent from the following description of preferred embodiments thereof shown inthe accompanying drawings, in which:

FIG. 1 is a partly sectional side view of the mechanical arrangement of a disc-shaped flashlight;

FIG. 2 is a reduced scale plan view of the flashlight according to FIG. 1 taken on line A-A and illustrating electrical connectors;

FIG. 3 is a reduced scale plan view of the lower reflector of FIG. 1 taken on line B-B;

FIGS. 4-6 are views similar to the one shown in FIG. 3 illustrating different embodiments;

FIG. 7 is a plan view of a reflector of a rectangular flashlight;

FIG. 8 is a top view illustrating the additional reflectors in a rectangular flashlight;

FIG. 9 is a sectional view of a disc-shaped flashlight of the rechargeable type;

FIG. 10 is a plan view illustrating the additional annular shaped reflectors;

FIG. 11 is a cross-sectional view of the additional reflectors; and

FIG. 12 is a circuit diagram of the rechargeable flashlight according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The housing of the flashlight is disc-shaped as can be seen in FIG. 1. The housing comprises a convex shell or bottom portion 1 and an annular cover or top bottom 2. Both shell 1 and cover 2 are screwed into each other by means of circumferentially placed threads. In a convex circular central aperture 3 of cover 2 a cover galss 4 is placed and secured which is made to conform to the disc-shape of the flashlight.

In the inner space of the flashlight an incandescent lamp 5 is placed into a socket 6 substantially coinciding with the minor axis of the housing. The socket 6, and

thereby lamp 5, are centered in the middle of the cover lished by conductors 17, 18 is opened or closed by means of a sliding switch 19 which is operated in turn by means of a knob 20 sitting in a recess 21 of shell 1 and conforming to the general disc-shape of the hous- Lamp 5 has a reflector 22 associated therewith. It comprises a pair of annular parabolically

shaped reflector segments

23, 24 the common focal point of which lies in the region of the filament 25 of lamp 5.

Reflector segments

23 and 24 have different diameters and thereby they have different focal lenths. Between the

parabolic reflector segments

23 and 24 an annular flat zone 26 is formed. In addition, the inner reflector segment 24 terminates in a annular flat zone 27. The

flat zones

26 and 27 are so directed that no direct light falls on them from lamp 5. Thereby, it becomes possible that the

parabolic reflector segments

23 and 24 obtain a maximum magnitude expressed in terms of optimum reflection.

Reflector segments

23, 24 and

zones

26, 27 are the parts of a single reflector having a circular outer edge 28 by means of which the reflector sits in a centered manner on a circular inner edge 29 of cover 2.

The structural depth of the housing corresponds to the length of the lamp 5.

Batteries

10, 11 disposed on both sides of lamp take up about half of such height. The remaining space between the batteries and the cover is taken up by the cascade-shaped reflector 22.

The light falling on the

parabolic reflector segments

23, 24 becomes reflected in substantially parallel beams in the direction of the transverse axis of the flashlight. The curvature of the cover glass 4 causes a convergence of the light beams emitted by the reflector 22. A parallel light beam is formed outside the flashlight by the appropriate correlation of the radii of the inner and outer curvatures of the cover glass 4. Across the

zones

26, 27 lying in shade are additional reflectors formed in a region which can be reached directly by the light beams coming from lamp 5. The additional reflectors 30 are formed on the cover glass itself. They are annular in shape and they reflect the light falling on them in a parallel manner with respect to the light beams leaving the flashlight. In this additional arrangement, the light beams of lamp 5 fall on the cylindrical surfaces of reflectors 30 which face the lamp 5 and become totally reflected by their backside 31. The backside 31 is tangential to an imaginary parabolic surface and passes through a point of tangency which is defined by a light beam considered as being median with respect to the height of the reflector 30. The flat formation of backside 31 simplifies the production of the cover glass. It is, however, also possible to make sides 31 also as parabolic surfaces. It is within the scope of the present invention to make the reflector segments which in each case have a common focal point and different focal lengths in a varied form in order to adjust their structure to the space conditions within housing. The reflector segments may, for example, be made as

parallel stripes

32, 33, 34 of a single reflector as shown in FIG. 4 wherein the middle stripe 33 has the shortest focal length, while the reflector segments 32, 34 adjoining the middle stripe 33 have a median focal length and the remaining reflector 35 has the longest focal length. At each end of the

reflector stripes

32, 33, 34

flat surfaces

36, 37, 38 are provided as dark zones.

A further embodiment of the reflector is shown in FIG. 5 in which the segment-shaped

reflector segments

39, 40, 41 have focal lengths which become larger as going from the inner segments toward the outer segments.

FIG. 6 illustrates a segment-type reflector 4t having segments 43, with a lamp 46

reflector having segments

43, 44 in the center of reflector 45 in the plane thereof. The shade producing socket 47 is facing the smallest reflector segment 43 so that by this arrangement the light loss becomes the smallest. Reflector segment 43 has the smallest focal length, the middle reflector segment 44 has a median focal length, while reflector 45 has a maximum focal length.

The

annular segments

48, 49 adjoining

reflector segments

43, 44 and having short focal lengths, lie in shade produced by the

reflector segments

43, 44. The space obtained beneath the reduced reflector segments is used for necessary structures, such as, batteries, thereby an increase of the structural depth of the flashlight is avoided.

FIG. 7 illustrates a further embodiment of the present inventive flashlight as being rectangularly shaped. In this embodiment four batteries are arranged in the housing in the form of a rectangle (not shown). In the middle of the housing in the direction of the transverse axis thereof a lamp 50 is placed.

The rectangular housing is formed to accommodate the reflector by making same in a circular shape 51 having four segments 52 of which has a larger focal length than the reflector 51 itself and each of which is formed to extend into a corner portion of housing 53. An additional reflector in this embodiment is formed on the cover glass and is sub-divided into a plurality of paraboloid shaped reflectors 54 which totally reflect the light individually. These last-mentioned reflectors have their commom focal point in lamp 50 notwithstanding the fact that they have different focal lengths even though the paraboloids 54 form a rectangle. The above-described reflector can be adjusted to fit into a housing having a different form, such as an oval shape.

With reference to FIGS. 9-12 a further embodiment of the present invention is shown in the form of a discshape flashlight having a pair of

rechargeable batteries

55, 56. The disc-shaped housing 57 is not split about its circumference as it was the case of the flashlight shown in FIG. 1. On the front side a cover glass 58 s removably arranged so that the lamp 59 cu be replaced if necessary.

The

rechargeable batteries

55, 56 are supplied with energy from solar cells 60 which are placed into the annular dark zone 61 of reflector 62. Such solar cells operate to recharge the associated batteries when exposed to sunlight.

The plus terminal of the solar cell 60 is connected through a diode 63 over a conductor to the series connected

batteries

55, 56 and also to a terminal of lamp 59. Diode 63 prevents the discharge of

batteries

55, 56 over the solar cells 60. Between lamp 59 and the negative terminal of

batteries

55, 56 and also between solar cells 60 and the positive terminal of the batteries 55, 56 a switch 64 is placed which connects the

batteries

55, 56 selectively either with the solar cells 60 or with lamp 59. The switch 64 prevents that the solar cells 60 directly feed the lamp 59.

The invention in a further embodiment thereof provides that the additional

annular reflectors

65, 66, 67 are supported by a star-shaped arm structure 68 and are secured on the edge of the cover glass 69 as a unit. The contour of

reflectors

65, 66, 67 facing the cover glass 69 is shaped to adjust itself to the inner curvature of cover glass 69. The invention also provides the possibility that the arms 68 are slightly extended and securely grip corresponding recesses of the cover glass.

From the above, it is apparent that although the invention has been described hereinbefore with respect to certain specific embodiments thereof, it is evident that many modifications and changes may be made without departing from the spirit of the invention. Accordingly, by the appended claims, we intend to cover all such modifications and changes as fall within the true spirit and scope of this invention.

We claim:

1. In a. flashlight having a two-piece housing assembled of a convex bottom piece and an annular top piece,

a convex cover glass connected to said annular top piece,

the combination comprising a recess defined in the central portion of the inner surface of said cover glass,

resilient electrical contact means arranged near a central portion of said bottom piece, the connection line of the centers of said opposite central portions defining the optical axis of said flashlight, the rim of said recess being adapted for contacting a bulb portion of a lamp and said contact means being adapted for electrically connecting said lamp to a power source and for urging the base of said lamp in the direction toward said recess, said lamp defining a light source point on said axis,

at least a pair of annular parabolic mirrors concentrically arranged at a spaced relation from each other around said axis, each of said mirrors having a different focal length and a common focal point coinciding with said light source, at least one annular nonreflecting surface extending between said parabolic mirrors in the direction of light rays from said light source,

reflecting rings concentrically arranged around said recess on said inner surface of said convex cover glass so as to reflect light rays from said light source into the shadow zones on said cover glass caused by said nonreflecting surface.

2. A pocket size flashlight for use in connection with a bulb having a base and a head, said flashlight including a casing having a bottom portion and a removable cover including a cover glass, and a light reflector operatively arranged within said casing spaced apart from said cover glass,

comprising, in combination,

bulb receiving means secured to said bottom portion of said casing and being adapted to receive the base of said bulb,

said cover glass being adapted to be in contact with said bulb head, whereby said bulb will be adapted to be held in a fixed position between said cover glass and said bulb receiving means, said reflector having at least a pair of effective reflecting regions, each of said regions having a different focal length and a common focal point, the center of said bulb head being placed in said focal point, said reflecting regions being formed as parabolic mirrors, said reflector including nonreflecting region means, additional reflector means having a focal point, said additional reflector means being disposed in relation to said nonreflecting region means to substantially eliminate the nonreflecting effect thereof.

3. The flashlight as claimed in claim 2, wherein said parabolic mirrors are annularly shaped.

4. The flashlight as claimed in claim 2, wherein said parabolic mirrors are stripe shaped.

5. The flashlight as claimed in claim 3, wherein said parabolic mirrors comprise segments.

6. The flashlight as claimed in claim 4, wherein said parabolic mirrors comprise segments.

7. The flashlight as claimed in claim 2, wherein said parabolic mirrors form a single reflector structure.

8. The flashlight as claimed in claim 2, further comprising cover glass means, said additional reflector means being formed on said cover glass means.

9. The flash light as claimed in claim 2, further comprising cover glass means, said additional reflector means being secured to said cover glass means.

10. The flashlight as claimed in claim 8, Wherein said additional reflector means is annular.

11. The flashlight as claimed in claim 2, further comprising a source of power and means for recharging said source.

12. The flashlight as claimed in claim 11, wherein said recharging means comprises solar cell means disposed adjacent said nonreflecting region means.

13. The flashlight as claimed in claim 2, wherein said flashlight has a disc shape.

14. The flashlight as claimed in claim 2, having a diameter of about 6.5 cm.

15. The flashlight as claimed in claim 2, further comprising cover glass means including means for securing said light source in a central portion thereof.

Claims

1. In a flashlight having a two-piece housing assembled of a convex bottom piece and an annular top piece, a convex cover glass connected to said annular top piece, the combination comprising a recess defined in the central portion of the inner surface of said cover glass, resilient electrical contact means arranged near a central portion of said bottom piece, the connection line of the centers of said opposite central portions defining the optical axis of said flashlight, the rim of said recess being adapted for contacting a bulb portion of a lamp and said contact means being adapted for electrically connecting said lamp to a power source and for urging the base of said lamp in the direction toward said recess, said lamp defining a light source point on said axis, at least a pair of annular parabolic mirrors concentrically arranged at a spaced relation from each other around said axis, each of said mirrors having a different focal length and a common focal point coinciding with said light source, at least one annular nonreflecting surface extending between said parabolic mirrors in the direction of light rays from said light source, reflecting rings concentrically arranged around said recess on said inner surface of said convex cover glass so as to reflect light rays from said light source into the shadow zones on said cover glass caused by said nonreflecting surface.

2. A pocket size flashlight for use in connection with a bulb having a base and a head, said flashlight including a casing having a bottom portion and a removable cover including a cover glass, and a light reflector operatively arranged within said casing spaced apart from said cover glass, comprising, in combination, bulb receiving means secured to said bottom portion of said casing and being adapted to receive the base of said bulb, said cover glass being adapted to be in contact with said bulb head, whereby said bulb will be adapted to be held iN a fixed position between said cover glass and said bulb receiving means, said reflector having at least a pair of effective reflecting regions, each of said regions having a different focal length and a common focal point, the center of said bulb head being placed in said focal point, said reflecting regions being formed as parabolic mirrors, said reflector including nonreflecting region means, additional reflector means having a focal point, said additional reflector means being disposed in relation to said nonreflecting region means to substantially eliminate the nonreflecting effect thereof.

14. The flashlight as claimed in claim 2, having a diameter of about 6.5 cm.