US 3793514 A
A lamp assembly for illuminating an instrument panel, which facilitates replacement of lamps and increases the amount of useful light from them, including a transparent housing located in a panel recess, a lamp assembly in the housing, and a cap that can be screwed into the housing to hold the lamp assembly in place. The lamp assembly includes a lamp and a pair of spring-like terminal members permanently attached to the lamp leads and having folded-over portions that are pressed together as the cap is screwed into the housing, to assure good electrical contact between the terminals and a pair of contacts mounted on the housing. The housing has a series of ring-shaped regions that are beveled, so they refract and reflect light sidewardly to better illuminate adjacent regions of the panel.
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United States Patent 1191 Curl Feb. 19, 1974 PANEL LAMP ASSEMBLY Prima Examiner-Richard M. Sheer 1 we ldAdClRd d, W  nven or ii r m ur 6 mon Attorney, Agent, or FirmL1ndenberg, Freilich &
Wasserman 1  Assignee: Bell Industries, Inc., Los Angeles, 1
57 ABSTRACT 9 P 1972 A lamp assembly for illuminating an instrument panel, [211 App]. No 241,295 which facilitates replacement of lamps and increases v the amount of useful l1ght from them, mcludmg a transparent housing located in a panel recess, a lamp U-S. Cl- L assembly in the housing and a cap can be [5 Cl. crewed into the housing to the lamp assembly in Fleld of Search U... 8.16, place The lamp assembly includes a lamp and a pair 339/170, 125 L of spring-like terminal members permanently attached to the lamp leads and having folded-over portions that References Cited are pressed together as the cap is screwed into the UNITED STATES PATENTS housing, to assure good electrical contact between the 3,610,911 10 1971 Curl 240/8.l6 terminals and a P Of contacts mounted on the bolls- 3,638,009 1 1972 Strianese... 240/8.16 x g- The housing has a Series of ring-Shaped regions 2,831,453 4/1958 Hardesty 240/2.1 X that are beveled, so they refract and reflect light side- 1,767,l79 6/1930 Johns 240/46L5l wardly to better illuminate adjacent regions of the 2,703,398 3/1955 Harrington et al. 240/8.l6 PaneL 2,948,073 8/l960 Roper 240/8.16 3,604,919 9/1971 M'acPherson 339/125 L X 5 Claims, 10 Drawing Figures 6 L 5g 6 3 e. i 64. r r 32 4 ,3 i l 5 \\\\\\\\\\w1-i\\s V I 1 l 4 l 6 e, k
PATENTED FVEBI 1 9 .1914
SHEEY 2 0F 3 PANEL LAMP ASSEMBLY BACKGROUND OF THE INVENTION This invention relates to panel lamp assemblies.
Instrument panels on aircraft often utilize a transparent sheet which is illuminated by several lamps located within the sheet. The panel sheet is covered with an opaque material except for regions in the shape of numbers or letters where light can pass through to identify the positions of switches, instruments, and other devices of the panel. Small lamp assemblies are utilized to enable reception in relatively thin panel sheets without projecting behind them. The apparatus for holding the lamp assemblies can be constructed compactly and still permit rapid replacement of a lamp when it burns out. However, it is difficult to also assure reliable connections of the lamp to electrical conductors that supply lamp energizing current, so that the lamps will operate reliably in spite of severe vibrations or the like that may be encountered in service. The lamps generally project light in all directions, but it is primarily the sidewardly projected light that is useful in illuminating characters defined in the panel. It would be desirable to provide compact lamp assemblies that projected large portions of their light sidewardly, to increase the useful output from the small lamps.
SUMMARY OF THE INVENTION and inner ends located on either side of the lamp. A 7
pair of terminal numbers are welded to the lamp leads and lie on either side of it so they are pressed against the contact members as the cap is screwed in. The terminal members are constructed of spring material with folded-over portions that are compressed against the contact members, to assure reliable electrical contact with them even if the cap is slightly loosened.
The transparent lamp housing has a front surface forming several ring-shaped regions that are beveled so that some of them can refract forwardly traveling light rays from the lamp into a sideward direction. The other beveled regions are at such an angle as to reflect light rays due to total internal reflections by the material. The housing is provided with another laterally extending surface lying behind the lamp filament and covered with a reflective material so that rearwardly traveling light rays are also reflected sidewardly.
The novel features of the invention are set forth with particularity in the appended claims. The invention will best be understood from the following description when read in conjunction with the accompanying drawmgs.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional perspective view of a panel apparatus constructed in accordance with the invention;
FIG. 2 is a perspective, exploded view of the housing and lamp assembly of FIG. 1;
FIG. 3 is an exploded perspective view of the lamp assembly of FIG. 2;
FIG. 4 is a sectional side view taken on the line 44 of FIG. 1;
FIG 5 is a partial sectional view of the apparatus of FIG. 4; showing the manner in which light is sidewardly directed'from the lamp;
FIG. 6 is a view taken on line 6-6' of FIG. 4;
FIG. 7 is a partial perspective view of a panel apparatus constructed in accordance with another embodiment of the invention;
FIG. 8 is a perspective, exploded view of the housing assembly of FIG. 7;
FIG. 9 is a partial sectional side view taken on line 9-9 of FIG. 7; and
FIG. 10 is an exploded bottom perspective view of still another lamp apparatusof the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates a portion of a panel assembly which inlcudes a panel 10 of light transmitting material with a lamp assembly 12 installed in a rearwardly opening recess 14 of the panel. The panelalso has grooves 16 in its rear surface for holding electrical conductors 18 that supply current to energize the lamp in the lamp assembly 12. A board (not shown) lies behind the panel 10. Light emitted from the lamp passes along the panel 10 and can illuminate areas of the panel that are open to the passage of light. A layer of translucent white material, such as paint 20 coats-the panel 10, while the layer of opaque material 22 lies over the translucent layer. The panel is devoid of an opaque cover at selected regions such as those defining the ON and OFF signs 24, 26 which lie adjacent to a switch 28 mounted on the panel.
FIGS. 2-4 illustrate details of the lamp assembly 12 which is installed in the panel. The lamp assembly includes a housing 30 constructed of transparent material such as acrylic, a pair of contacts 32, 34 that extend through slots 36, 38 in the housing, and an insert assembly 40 which is constructed to be readily insertable into the housing 30. The insert assembly 40 includes a lamp 42 and a pair of terminals 44, 46 electrically connected to leads of the lamp. The lower portion of the lamp is surrounded by a insulator ring 48 and an insulator washer 50 which are held by a threaded cap. When the cap 52 is screwed into a rear opening of the lamp housing 30 to position the lamp 42 therein, the terminals 44, 46 are pressed against inner ends of the contacts 32, 34. This completes an electrical path from the panel conductors 18, through the contacts 32, 34, the terminals 44, 46 and the leads and filament of the lamp, to enable energization of the lamp.
The lamp housing 30 may be permanently installed in the panel 10 by gluing or the like, and the contacts 32, 34 are permanently installed in the lamp housing and panel and permanently connected to the electrical conductors 18. When a lamp burns out, it is only necessary to remove the insert assembly 40 by screwing it out and replacing it with another insert assembly that may be pre-assembled in a factory. When the cap 52 of the insert assembly has been fully screwed into the lamp housing, the terminals 44, 46 will press firmly against the contacts 32, 34. However, during the subsequent period of use, the cap 52 may loosen slightly dur to vibrations, and it is important to maintain good electrical contact even if there is slight loosening. To assure continuity in the electrical circuit, the terminals 44, 46 are each constructed of a resilient electrically conductive material, and are formed with folded-over portions 56 to bear against the contacts 32, 34. As the cap 52 is tightened, the folded-over portions 56 are resiliently compressed, which assures maintenance of pressure against the contacts 32, 34 even if there is a slight loosening of the cap or any relaxation of the portions pushing the terminals against the contacts.
The lens 30 is formed with a central, rearwardly opening recess 60 for receiving the lamp 42, and is formed with the pair of slots 36, 38 extending sidewardly therethrough and intersecting the lampreceiving recess 60. The contacts 32, 34 are installed by merely inserting their inner ends 321, 341 through theslots 36, 38 of the housing. The housing is provided with a bead 62 that engages a corresponding groove portion 64 in each of the contacts to closely locate the contacts. The inner portions 321, 34I of the contacts are rounded to closely engage the lamp 42 when it is in place in the housing.
The insert assembly 40 is constructed by first attaching the terminals 44, 46 to leads 66, 68 of the lamp 42. This may be accomplished by welding to assure a permanent and low resistance contact between them. The terminals have rounded inner portions 441, 461 (FIG. 3), which partially encompass the lamp to provide a relatively wide area of contact with it that minimizes localized high pressures. The inner portions 441, 46l are cemented to the lamp to securely hold them thereon and to fix the position of the lamp filament relative to the terminals. The terminal 44, 46 are installed within the insulator ring 48 on top of the insulator washer 50 and with tabs 70, 72 formed on the terminals lying under the insulator ring. The insulator ring 48 may be dropped into a recess in the cap 52, and may be glued in place to facilitate handling of the insert assembly during installation in the panel.
As threading of the insert assembly 40 into the housing 30 begins, all portions of the insert assembly rotate together. However, when the folded-over portions 56 of the terminal enter the slots 36, 38 they no longer turn with the rest of the insert assembly, but instead remain aligned with the contacts 32, 34. Further tightening of the cap causes compression of the folded-over terminal regions against the contacts, and the installation is then complete.
When the lamp is installed, the lamp filament 80 lies behind the front surface 82 of the lamp housing and most of it lies in front of a ring-shaped land 84 (FIG. that extends sidewardly, or laterally, from the lamp recess 60 in the housing. The position of the lamp filament 80 is known, because the terminals 44, 46 are fixed to the lamp at positions that will result in proper lighting when the lamp is installed in the housing. If no special measures are taken, much of the light emitted from the lamp filament will pass in a generally forward direction through the front surface 82 of the housing or in a generally rearward direction through the land region 84. In many installations, the illuminated characteristics, such as those at 24, 26, are not located directly in front of the lamp, so that only the sidewardly directed light is useful.
In order to increase the useful light, the front surface 30 of the lamp is formed with several ring-shaped surfaces, as best shown in FIG. 5, which are beveled from the plane of the front surface which is indicated by the imaginary plane 100. These ring-shaped surfaces 91, 92, 93, 94, 95, and 96 coincide with the surfaces of imaginary cones whose apexes lie at the center of the lamp 42 along the axis 104. Some of the ring-shaped surfaces 91, 93, and 96 are formed so that the imaginary cones on which they lie have apexes lying behind the front plane 100 of the housing. These ring-shaped surfaces form angles such as angle A, between normals such as 96N to their surfaces and light rays such as 102 from most of the lamp filament, which exceed the critical angle of refraction for the material of the housing 30. In the case of acrylic, the critical angle of refraction is about 42, and where the angle A exceeds this value any light reaching the surface is totally reflected instead of passing through the surface. Accordingly, the rays such as 102 are directed in a primarily sideward direction so they can be useful in illuminating areas of the panel 10 around the lamp assembly, instead of merely passing through the housing and being largely absorbed by the translucent and opaque coatings immediately in front of the lamp assembly (or illuminating too intensely any character directly in front of the lamp).
It can be seen that those internally-reflecting beveled surfaces 91, 93, and 96, which are of progressively greater diameter are beveled at progressively smaller angles from the plane 100; in other words, they lie on imaginary cones whose apexes are located progressively more forward towards the front plane 100 of the housing. This permits use of wider ring-shaped areas at the outer regions while still assuring a greater than critical angle for most of the light reaching the housing surface.
Light rays which strike the beveled surfaces 92, 94 that are not angled to provide internal reflections, are sidewardly reflected by utilizing light reflective coatings such as films of aluminum on these surfaces. In order to better utilize light rays such as 106 thatare directed on a largely rearward direction from the lamp filament, the land 84 of the housing is coated with a light reflective coating 108. this coating 108 reflects rearwardly directed light rays striking it, in a large outward and forward direction.
FIGS. 7, 8, and 9 illustrate another embodiment of the invention which utilizes a'modified housing. FIG. 7 illustrates the lamp assembly 110 mounted on a circuit board 112 which includes a core 114 of insulative material and separated regions 116, 118 of sheet copper for connection to contacts 120, 122 of the lamp assembly. The circuit board with the lamp assembly 110 thereon can be installed at the rear of a transparent panel of the type shown in FIG. 1. i
As shown in FIG. 8, the housing of the lamp assembly includes a forward housing part 124 and a separate rearward housing part 126. The forward part 124 is constructed of a good optical material such as acrylic, while the rearward parts 126 are constructed of a strong material such as glass filled ABS plastic. This permits the attainment of greater strength at the threaded part of the housing, which is on he rearward housing part 126, without sacrificing optical properties for the forward part. The only housing surfaces which are coated with a reflective material are on the forward part 124, and a reflective coating corresponding to that at 108 in FIG. 5 does not have to be formed within a deep recess. A pair of contacts 128, 130 fit over wedgeshaped projections 132, 134 on the rearward housing part 126. Ears 132 on the contacts closely surround the housing parts and resist twisting or cocking of the housing. A rib 134 of the lower housing part and dents 136 on the contacts 128, 130 facilitate sonic welding of the contacts to the housing and of the housing parts 124, 126 to each other.
The lamp assembly 110 is also provided with a light distributing screen 138 located in front of the lamp, to reduce the amount of light that shines direcely to the front of the lamp. The screen 138 has numerous holes to allow a small amount of light to be directed forwardly, but it also reflects a large amount of the forwardly directed light so it can travel sidewardly. A variety of screen types can be utilized, such as a 200 mesh stainless steel screen which may be plated with silver or other material to further increase its reflective properties, or may be a sheet with a chemically etched pattern of holes. The screen not only acts as a light controller, but also serves as a heat sink'to better distribute heat from the lamp to the rest of the panel assembly.
FIG. illustrates another lamp assembly which includes a pair of lamps 140, 142 that are held in an elongated housing 144 by a pair of insulator ringsl46, 148, a pair of washers 150', 152 and a pair of caps 154, 156. A pair of terminals 158, 160 fastened to the outside of each lamp connect one lead of each lamp to a contact 162, 164 which can connect to a current carrying conductor. Another pair of terminals 166, 168 connect the other lead of each lamp to a common contact 170 which can connect to another current carrying conductor. Another pair of terminals 166, 168 connect the other lead of each lamp to a common contact 170 which can connect to another current carrying conductor. The lamp assembly is otherwise similar to the assemblies previously described. I
Thus, the invention provides a lighted panel with a miniature lamp assembly which facilitates replacement of burned out lamps and which increases the amount of light from the lamps. Replacement of burned out lamps is facilitated by providing terminals permanently fastened to the leads of the lamp and constructed of resilient material with folded over portions which are compressed as a retaining cap is tightly screwed into a lamp housing during replacement. The filament of each lamp is positioned for good utilization, because the filament position is fixed with respect to terminals that are held at closely determined positions in the lamp. The amount of useful illumination is increased by forming beveled regions in the front of the lamp housing which direct forwardly moving light rays into a largely sideward direction, and by utilizing a reflective lamp in the lamp housing located behind the filament for reflecting rearwardly directed light rays into a sideward direction.
Although particular embodiments of the invention have been described and illustrated herein, it is recognized that modifications and variations may readily occur to those skilled in the art and consequently it is intended that the claims be interpreted to cover such modifications and equivalents.
What is claimed is:
l. A light panel assembly comprising:
a light-transmitting panel having a panel recess in its rear surface;
a plurality of electrical conductors extending. adjacent to said panel;
a housing closely received in said panel recess, said housing having an internally threaded housing recess in its rear surface and having a pair of sidewardly extending slots intersecting said housing recess;
a pair of contacts having inner and outer ends and extending through said slots so that the inner ends of said contacts lie within said housing recess while the outer ends of said contacts lie outside said housing;
means for electrically connecting said outer ends of said contacts to said electrical conductors;
a lamp shaped to fit within said housing recess, said lamp having a pair of leads;
a pair of terminals constructed of spring material and permanently electrically connected to said leads of said lamp, said terminals having forward portions that are folded-over to permit resilient compression in the direction of threading of an end cap assembly into said housing; and
a cap assembly with external threads for threadable insertion into said internally threaded housing recess, said cap assembly having terminal-engaging surfaces that press said terminals against said contacts as said cap assembly is screwed into said housing to compress said folded-over terminal portions in the direction of threading of said cap assembly into said housing recess.
2. The assembly described in claim 1 wherein:
said terminals are mounted to permit rotation relative to said cap assembly, so that the terminals can be compressed against said contacts without turning relative to themas said cap assembly continues to be turned.
3. The assembly described in claim 1 wherein:
said housing is made of transparent material and has a front which includes a plurality of ring-shaped regions that are beveled from an imaginary plane parallel to the front surface of the panel, some of said ring-shaped regions being beveled so they lie on the surfaces of imaginary cones whose apexes are be hind the front surface of the housing;
the transparent materialof the lamp housing having a critical angle of refraction of approximately 42, so that light rays striking an internal surface at an angle from the normal which is more than said critical angle are internally reflected instead of passing outof the lamp housing, and said ring-shaped regions are beveled so that light rays from the lamp filament that reach said ring-shaped regions are incident at more than 42 thereon, whereby the light rays are internally reflected into a sideward direction.
4. The improvement described in claim 3 wherein:
said ring-shaped regions which lie on imaginary cones whose apexes are behind the front surface of the housing, are beveled at progressively smaller angles from the plane of said housing front surface for ring-shaped regions of progressively greater diameter.
5. In a panel assembly which includes a lighttransmitting panel with a rear panel recess, a housing in the panel recess, the housing having a housing recess and being internally threaded to receive a cap assembly that covers the housing recess, a pair of electrical 7 8 contacts extending through the housing for connection an end cap assembly with external threads for threadto a current source, and a lamp received in the housing able insertion into the internally threaded housing recess and having a pair of lamp leads, the improverecess, said cap assembly having terminal-engaging ment comprising: surfaces that press said terminals against said a pair of terminals constructed of spring material and contacts as said cap assembly is screwed into the connected to the lamp leads,said terminals having housing to compress said.folded-over terminal porforward portions that are folded-over to permit retions in the direction of threading of the cap assemsilient compression in the direction of threading of bly into the housing recess. an end cap assembly into the housing; and
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