Apparatus For Illumination Of Instrument Faces

Abstract

A lamp cartridge for insertion in the edge of a light conductive block for distributing light to an instrument or instrument panel. The cartridge includes spring clip contacts along opposite sides thereof for making resiliently biased contact with bus bars in the light block, guides for orienting the clips in relation to an opening in the light block for receiving the cartridge, and an exposed portion facilitating manual insertion or withdrawal of the cartridge with respect to the opening.

Description

BACKGROUND OF THE INVENTION

The present invention concerns improvements in integrally illuminated edgelighted instruments or instrument panels; i.e. those employing light block conductors. Conventional illuminated instruments or instrument panels of this type do not provide for ready replacement of the lighting means, usually an incandescent lamp or several such lamps. In the event of lamp failure, the instrument or panel must be disassembled in some manner in order to provide access to the lamp for its replacement. Typically, lamp replacement requires detaching the lighting assembly from the instrument mechanism, followed by further removal of pointers, dial, light conductor etc. before access is gained to the inoperative lamp. In most assemblies, the lamps are soldered to a printed circuit board or held in place by other mechanical fastening means. To disassemble an instrument or panel is time consuming, costly and normally requires instrument recalibration after reassembly. In order to avoid the above difficulties, some instruments are designed for front lamp replacement and some edgelighted panels are designed for rear surface replacement. Unfortunately, both of these solutions are mechanically limited, waste space, and front lamp replacement configuration significantly obstruct the panel presentation.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a perspective view of an edge lighted instrument showing the lamp cartridge of the present invention in position immediately prior to its insertion into the light block of an instrument;

FIG. 2 is a front view of the instrument of FIG. 1 with portions of the light block in cross section and the lamp cartridge of the invention in position therein;

FIG. 3 is a cross section taken in the direction of arrows 3--3 of FIG. 2;

FIG. 4 is a cross section taken in the direction of arrows 4--4 of FIG. 3; and

FIG. 5 is an enlarged detail of portions of the lamp cartridge of the invention.

DESCRIPTION OF A PREFERRED EMBODIMENT

Referring to the drawing, an integrally lighted instrument body 10 has been illustrated which includes a cylindrical light conducting block 11 of Lucite, or material having similar properties. Although the application of the invention as shown and described herein is made with reference to a single instrument, it should be understood that the principles of the invention are as readily applied to edge lighted instrument panels. A face or dial 12 includes various indicia 13 which will transmit light from the interior of the block 11. An opaque light absorbent coating covers the face 12 the sides and rear areas of block 11 to prevent light from escaping from within the light block 11 except through the various indicia. The block 11 has a central axial opening 15 which receives a shaft 16 integrally connected to an outer hub 17 and pointer 18 all formed of light conducting material. Hub 17 is coated with an opaque light inhibiting medium but not the shaft 16 or pointer 18 and consequently, when the light block 11 is illuminated light will be conducted to the pointer 18.

In accordance with the present invention, the block 11 has been provided with a more or less radially directed bore 19 proceeding into side 11b of the light block and whose terminal end 19a is approximately adjacent to the central opening 15 in the block 11. The outermost end 19b of the bore 19 is of greater diameter than the diameter of the terminal end 19a and the bore includes a semicircular longitudinal groove 19c for reasons which will be explained.

As seen in FIGS. 3-5, parallel bus bars 20, 21 extend tangentially through the block 11 in a manner such that inner edge portions 20a, 21a protrude into the greater diameter section 19b of the bore 19 for a distance less than the internal diameter of section 19a. Ends of the bus bars are soldered to electrical leads 23, 24 which provide direct current from a battery (not shown).

In combination with the foregoing a unique lamp cartridge 26 has been devised which can be readily inserted into the bore 19 and removed therefrom when lamp failure has occurred. The cartridge 26 includes a plastic lamp holder 27 which mounts a lamp 28. The lamp 28 is a standard unbased type having two lead wires 29 and 30 (FIG. 5) which pass through clearance holes 29a, 30a in the lamp holder 27 and are connected to spring clips 31 and 32. These clips, one at each side of the holder 27 have their ends bent over the top of the body of the holder and thus clamped to it. They have straight sections 31a, 31b, and 32a, 32b which diverge from the lamp holder and adjoin at high points 31c, 32c. At the ends furthest from the lamp 28, clips 31 and 32 have rounded shoulders 31d and 32d. Recesses 27b formed in the lamp holder 27 receive the ends 31a, 32a of the clips 31, 32 and provide clearance to permit depression of the clip.

The lamp holder 27 includes the longitudinal spline 27a. A cap 33 is joined to the lamp holder 27 by pressure fit of a plug portion comprising the split tongue 33a into a recess 27c formed in the upper end of the lamp holder. The lamp lead wires are brought up through the recess 27c alongside the downwardly extending ends 31e, 32e of the spring clips and over the tops of the clips as shown. They are pressed into tight and secure electrical contact with the clips by the tongue of the cap. The split tongue 33a fits very tightly in the recess 27c and secures the cap firmly in place while at the same time holding the lead wires in secure electrical contact with the clips. The assembly is such that if the lamp burns out, the cap can be forced off, whereupon the lamp can be readily withdrawn from the holder and can be replaced by a new one. Of course, it is understood that alternatively the ends 31e, 32e of the spring clips could be soldered to the lamp wires 29 and 30 if it were desired to make the entire lamp cartridge 26 a replaceable item.

The cap 33 has a raised section 33b which together with the main part of the cap forms a lip or groove 33c. When the lamp cartridge 26 is to be inserted into the bore 19 of light block 11, the end of the cartridge will be held by the raised section 33b and the spline 27a will be aligned with groove 19c. This will properly position spring clip contacts 31 and 32 with respect to bus bars 20 and 21. The cartridge 26 may be inserted into the bore 19 and the clips 31, 32 will be forced inwardly into grooves 27b in the lamp body as the high points 31c, 32c of the spring clips are forced to pass by the bus bars 20 and 21. The clips sections 31b and 32b then resiliently cam the cartridge into its fully installed position wherein bus bars 20 and 21 rest against rounded shoulders 31d, 32d of the spring clips and against sections 31b and 32b. The cartridge 26 is readily removed without tools from the bore 19 by grasping the protruding cap section 33b between thumb and forefinger, with the thumbnail in groove 33c providing positive engagement.

In the operative position, the spring clips 31 and 32 exert a force against the bus bars 20 and 21 and prevent the cartridge from moving out of position. The spline 27a not only insures positive location of the component parts of the cartridge with respect to the bus bars but prevents rotation of the cartridge due to vibration.

The cartridge 26 can be fabricated from transparent components which will not cause light loss or blockage during operation. Clearance is provided around the lamp 28 in section 19a of the bore 19 so that colored filters can be used. If desired the cartridge and receiving bore can be fabricated in various lengths in order to allow the lamp to be located in its most efficient position within the lighting assembly, whether this be a light block for an instrument dial, or an edge lighted instrument panel.

It will be understood that the foregoing description relates to a particular embodiment of the invention and is therefore representative. In order to appreciate the scope of the invention, reference should be made to the appended claims.

Claims

We claim:

1. Means for illuminating an instrument face comprising:

a. a transparent light block adapted to be positioned directly behind said face;

b. a lamp-receiving recess formed in said block;

c. spaced bus conductors carried by said block and having portions thereof extending in exposed relation transversely across said recess; and

d. a lamp assembly removably inserted in said recess, said lamp assembly comprising:

1. a lamp holder,

2. an electric lamp carried by said holder, and

3. contact members exposed on the outside of said holder and electrically connected to light-producing means of the lamp, said contact members being resiliently mounted on said holder and including cam surfaces engaging the exposed portions of said conductors upon linear movement of said lamp assembly into said recess to electrically connect and mechanically hold said lamp assembly in said recess.

2. The illuminating means according to claim 1 wherein:

a. said lamp holder includes a cap having a section which projects from the light block when the lamp holder is fully received within said recess, said projecting section being formed so as to permit manual gripping thereof without the use of tools.

3. The illuminating means according to claim 1 wherein:

a. said contact members are flexible spring members having rounded end sections and being fixed at said rounded end sections to said lamp holder and extending freely toward the forward end of the lamp holder;

b. said recess is cylindrical in shape;

c. a groove is defined in the wall surface of the recess extending longitudinally thereof; and

d. a spline is formed on said lamp holder for reception in said groove, said spline aligning said spring contact members precisely in position for contact with the bus conductors when the lamp holder is inserted in the recess, said spline further preventing rotation of the lamp holder.

4. The illuminating means according to claim 1 wherein:

a. said lamp holder has a forward end and a rearward end with the forward end being adapted to be inserted into said recess first;

b. each of said contact members includes:

1.a first section diverging outwardly from said lamp holder as measured along said holder in a direction extending from said forward end toward said rearward end,

2.a second section converging inwardly toward said holder as measured along said direction, said second section being connected to said first section and forming a continuation thereof extending toward the rear end of said holder, and

3.a rounded end section located at the rearward end of the holder and forming a continuation of said second section at least one of said sections forming said cam surfaces; and

c. the exposed portion of each of said bus conductors being positioned within said recess in the path of movement of said contact members as the holder is inserted into said recess for riding along said first and second sections thereof and into seated relation at the juncture of the second section and the rounded end section.

5. Means for illuminating an instrument face comprising:

a. a transparent light block adapted to be positioned directly behind said face;

b. a lamp receiving recess formed in said block;

c. spaced bus conductors carried by said block and having portions thereof exposed within said recess; and

d. a lamp assembly removably inserted in said recess, said lamp assembly comprising:

1. a lamp holder having a forward end and a rearward end with the forward end being adapted to be inserted into said recess first,

2. an electric lamp carried by said holder at the forward end thereof,

3. a recess formed in the rearward end of the lamp holder,

4. spring contact members exposed on the outside of said holder and electrically connected to light-producing means of the lamp, said spring contact members being in resilient electrical contact engagement with the exposed portions of the bus conductors for conducting energizing power to the lamp and having their ends extending into the recess in the rearward end of said lamp holder,

5. wire leads extending from said lamp into the recess in the rearward end of the lamp holder and into contact with the spring contact members in said recess, and

6. a cap having a first section force fitted in the recess at the rearward end of the lamp holder against said wire leads and contact ends to hold them securely in place, and a second section projecting from the light block when the lamp holder is fully received within the lamp receiving recess formed in said block, said second section being formed so as to permit manual gripping thereof.