Bulb socket

Details Bulb socket Bulb socket

2002-05-30

2003-04-22

Feild, Lynn D. (Department: 2839)

Electrical connectors

With supporting means for coupling part

Coupling part or mating part extending into panel opening

Reexamination Certificate

active

06551133

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a bulb socket and more particularly to a bulb socket of a vehicular lamp.
2. Prior Art
Generally, a bulb socket is used to mount a bulb (a light source) to, for instance, a vehicular lighting fixture body so as to serve as a junction for power supply, and it has a socket body made from a synthetic resin.
The socket body typically includes a socket main portion, a flange portion, and engaging blocks. The socket main portion is constructed from a bulb fitting section and a power connecting section that are integrally formed in the axial direction. The flange portion extends radially from the outer surface of the socket main portion, and the engaging blocks also protrude from the outer surface of the socket main portion. The flange portion and the engaging blocks sandwich the edge portion of a socket mounting hole formed in the body of a vehicular lighting fixture, thus mounting the bulb socket to the vehicular lighting fixture.
In case the bulb socket needs a waterproof for the socket mounting hole, a packing made from a resilient material is generally superimposed on the front surface (i.e., the surface that faces the engaging blocks) of the flange portion of the socket body. The packing resiliently deforms between the edge portion of the socket mounting hole and the flange portion, thus preventing water from flowing into the socket mounting hole and also preventing the bulb socket from rattling.
If the bulb socket does not require waterproof for the socket mounting hole, no packing is used. As a result, it becomes necessary to find a measure to prevent the rattling of the bulb socket.
FIG. 8
shows such a measure used in a prior art bulb socket.
In this prior art bulb socket (h), resilient contact strips (d) and (e) are formed in the flange portion (b) that extends radially from the outer surface of a socket main portion (a), and each of the resilient contact strips (d) and (e) is spaced from the flange portion (b) by two slits (c). The resilient contact strips (d) and (e) have contact protrusions (g). The contact protrusions (g) are formed at tip ends of the contact strips (d) and (e) so as to protrude from the surfaces of the respective resilient contact strips (d) and (e), such surfaces facing the engaging blocks (f). In other words, the contact protrusions (g) are provided at the outer peripheral portions of the contact strips (d) and (e).
With the structure above, the edge portion of the socket mounting hole (not shown) is sandwiched by the engaging blocks (f) and the flange portion (b), and the contact protrusions (g) of the resilient contact strips (d) and (e) are brought into contact with the rear side of the edge portion of the socket mounting hole. In other words, the contact protrusions (g) contact one side of the edge portion that is the side opposite to the side which is in contact with the engaging blocks (f). As a result, the resilient contact strips (d) and (e) are deflected backwards, and resilient forces are applied to the resilient contact strips (d) and (e). The contact protrusions (g), as a result, come into resilient contact with the edge portion of the socket mounting hole, and the rattling of the bulb socket (h) is prevented.
In the above bulb socket (h), resilient forces caused by the deflection of the resilient contact strips (d) and (e) ensure that the bulb socket (h) be held while being prevented from rattling. However, the resilient contact strips (e) have a short length from their base ends to the contact protrusions (g); as a result, they do not have a sufficient flexibility. The problem caused is that a great force is required to mount the bulb socket (h).
More specifically, a bulb mounting portion in which the bulb socket (h) is to be mounted has a circular socket mounting hole and insertion notches formed in the edge of the socket mounting hole. When mounting the bulb socket (h), the engaging blocks (f) are inserted through the insertion notches, and the front part of the socket main portion (a) is inserted through the socket mounting hole to the depth of the flange portion (b). Keeping this state, the bulb socket is then turned as a whole in a predetermined direction until the engaging blocks (f) are located in the edge portion of the socket mounting hole so as to be at portions other than the insertion notches, so that the edge portion of the socket mounting hole is sandwiched in its axial direction (or form the front and rear sides of the edge portions) by the engaging blocks (f) and the flange portion (b). At this moment, the resilient contact strips (d) and (e) must be deflected in order to ensure that the engaging blocks (f) are located so that the surfaces of the engaging blocks (f) that face the flange portion (b) are coplanar with the front side surface of the edge portion of the socket mounting hole. Since the resilient contact strips (e) in the prior art bulb socket (h) lack flexibility, it requires a great force to obtain such a deflection in the strips e.i Thus, the bulb socket (h) is not easily mountable.
When the resilient contact strips (d) are designed to have a long length from their base ends to the contact protrusions (g), the resilient contact strips (d)l have a flexibility that is great enough to make it easy to mount the bulb socket (h). However, insufficient resilient forces obtained from the longer resilient contact strips (d) cause another problem. A sufficient mounting torque is not obtainable.
Furthermore, in the above prior art bulb socket, the resilient contact strips (d) and (e) are all in the shape of a cantilever spring. Accordingly, they are susceptible to breakage at their base ends if they receive a relatively large external force. This is another problem with the prior art bulb socket.
Moreover, so as for the resilient contact strips (e) to have a long length as that of the resilient contact strips (d), the slits (c) must be long enough to extend deep into the flange portion (b). The problem here is that the socket main portion (a) is under dimensional restrictions. Especially in the case of a bulb socket for a wedge-base bulb, a bulb holding portion (i) for holding the bulb cannot be shortened in the width direction of the base portion (see a bidirectional arrow A in
FIG. 8
) of the wedge-base bulb. For this reason, the relatively short resilient contact strips (e) can only be formed in opposed end portions in the width direction of the base portion, and the relatively long resilient contact strips (d) are thus formed in opposed end portions in a direction with the smaller dimension, namely, in the thickness direction of the base portion (see a bidirectional arrow B in FIG.
8
). The bulb holding portion (i) of such a bulb socket takes an oblong shape when viewed from the front. Since the glass bulb in the bulb socket has a circular shape when viewed from the front, the bulb holding portion (i) and the glass bulb are visually incompatible with each other and cause a problem of a diminution in visual attractiveness. In particular, vehicular lighting fixtures in recent years are designed so that the reflector forms the light distribution pattern, and the lens for covering the front of the lamp functions merely as a cover for the lamp. For this reason, there is a growing tendency to employ a so-called transparent lens that has no lens step. When a lighting fixture employs such a transparent lens (front cover), the inside of the lighting fixture is distinctly visible from the outside. Accordingly, visual attractiveness is the prerequisite even to the components disposed inside the lighting fixture such as a bulb socket.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a bulb socket that has a socket body made from a synthetic resin and is provided with engaging blocks and a flange portion for sandwiching an edge of a socket mounting hole from its opposed sides and that is easily and reliably mountable and is durable and visually attractive.
The above object is accomplished by a uniq

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