Light socket

Abstract: A light socket (10) for a light bulb (14) includes a contact base (15) that includes a right angle/single piece plastic socket portion (16,18) having a tubular part (16) into which a metallic ring-like member (44) is insertable and serves the dual purpose a light bulb retainer as well as the ground contact for the light bulb (14).

Description: This invention is related to light sockets and more particularly to a right angle plastic light socket in which the wire terminals are connected to the bulb contacts through a terminal housing formed generally perpendicularly to the longitudinal centre line of the light bulb. Vehicle tail light housings are frequently located on the interior of the exterior panels of the vehicle, in which case, there may be no need for sealing between the connecting interfaces of the light socket and the light housing. However, in some cases, it may be desirable to locate the light housing on the exterior of the outer panels of the vehicle, in which case the connecting interfaces are exposed to dirt, moisture and all weather conditions. In such cases, the connecting interfaces of the light socket and the light housing as well as the exposed portion of the light socket body should be sealed against all weather conditions and to prevent dirt and moisture from gaining access thereto and causing deterioration thereof. One type of light socket that heretofore has been used for providing a sealed light socket and light housing combination can be seen in US-A-3,982,813. Although the socket disclosed in this patent has been successfully used for this purpose, it is not entirely satisfactory from a manufacturing standpoint due to the fact that the plastic housing or body of the light socket is formed in two parts and requires the inner chamber thereof to be filled with grease. As a result, this socket has been found to be expensive to manufacture and, due to the number of parts involved, does not lend itself well to automated manufacture. The present invention seeks to provide an improved light socket. According to an aspect of the present invention, there is provided a light socket as specified in claim 1. It is possible with the present invention to provide a light socket for a bulb in which the socket body portion is formed as a one piece plastic member into which the light bulb retainer, the ground terminal and the feed terminals can be readily assembled by use of automated assembly equipment. The invention can also provide a new and improved light socket for a light bulb having a contact base that includes a right angle/single piece plastic socket body portion having a tubular part into which a metallic ring-like insert member is insertable which serves the dual purpose of a light bulb retainer as well as a ground contact for the bulb. It is also possible for the invention to provide a socket for a light bulb having a double-contact type base that is sealed against all weather conditions and is provided with a pair of feed terminals each of which has a cantilevered contact member the free end of which provides a wiping engagement with another part of the feed terminal each time a light bulb is inserted into the retainer located in the socket body portion. In some embodiments of the invention, it is possible to provide a light bulb socket for a light bulb having a double contact base in which the socket body has a pair of feed terminals each of which is provided with a cantilevered contact member which serves as a spring for firmly maintaining the light bulb within J-type slots formed in a ring-like bulb retainer press-fitted within the plastic one-piece socket body portion of the assembly and can also provide an electrical connection with one of the two contacts of the light bulb base. In an embodiment, there is provided a light socket assembly that is intended to receive a light bulb having a bayonet-type base with a double-contact. In the preferred form, the light socket comprises a single piece plastic socket body having a tubular socket portion which accommodates a bulb retainer/ground member and is integrally formed with a connector portion which houses the ground and feed terminals. The tubular socket portion is located along a first axis while the connector portion is located along a second axis which is substantially perpendicular to the first axis. The bulb retainer/ground member is located within an opening formed in the socket portion that is surrounded by an inner wall having a column member projecting radially inwardly from the inner wall with its longitudinal centre axis being located substantially parallel to the first axis. A guide slot is also formed in the inner wall at a point diametrically opposed to the column member and is located along an axis which is also substantially parallel to the first axis. The retainer/ground member is made of a metallic material and has a body portion in the form of a split ring with each of the opposed facing end surfaces being provided with a barb adapted to engage one side of the column member. A tongue depends from the body portion of the retainer/ground member and is adapted to be located in the guide slot for providing electrical contact with the ground terminal. In addition, each of the feed terminals has a cantilevered contact member located within the inner diameter dimension of the retainer/ground member whereby insertion of the light bulb into the retainer/ground member followed by rotation of the light bulb results in the double-contacts of the light bulb base making electrical engagement with the contact members of the feed terminals and firm retention thereby within the retainer ground member. An embodiment of the present invention is described below, by way of illustration only, with reference to the accompanying drawings, in which: Figure 1 is an exploded isometric view showing various parts of an embodiment of light socket; Figure 2 is a side elevational view showing the light socket of Figure 1 assembled and mounted within a panel portion of a light housing; Figure 3 is a plan view of the light socket of Figure 1 with the bulb removed; Figure 4 is a sectional view of the light socket taken along line 4-4 of Figure 3; Figure 5 is a sectional view of the light socket taken along line 5-5 of Figure 3; Figure 6 is an enlarged isometric view of a retainer/ground member forming a part of the light socket of Figure 1; and Figure 7 is an enlarged plan view with some parts broken away and/or removed so as to show in detail the design of the light socket and the interconnection of the retainer/ground member and ground terminal. Referring to Figures 1 to 3, a light socket 10 is shown for mounting on a rear panel portion 12 of a light housing (such as found in tail light assemblies or side indicator lights of a motor vehicle) for locating an electrically energisable bulb 14 in a desired axial and rotational position with respect to the optical components of the light housing. The light socket 10 is suitable for applications in which the rear panel portion 12 is located in an exposed position, subject to all weather conditions, and requiring an effective seal of the light socket 10 and of the interface between the light socket 10 and the panel portion 12. As mentioned, the panel portion 12 forms the rear wall of a light housing in which the light bulb 14 must be accurately positioned with respect to a lens and/or a parabolic reflector for directing light from the light housing when the light bulb 14 is energised. Typically, the rear surface of the light housing will be located in close proximity to a vehicle body component. The light socket 10 includes a right angled socket body consisting of a generally tubular portion 16 formed integrally with a generally rectangular connector portion 18. The tubular portion 16 is formed with a cylindrical outer peripheral wall 20 having a diameter slightly smaller than a central circular mounting hole 22 in the panel portion 12. Although not shown, the mounting hole 22 includes the usual clearance slots to ensure that the tubular portion 16 of the socket body 15 will fit only one way axially through the mounting hole 22. In this regard and as can be seen in Figure 1, retention flanges or ears 24, 26 and 28 are formed on the upper periphery of the wall 20 of the tubular portion 16 and extend towards an annular flange 30 integrally formed with the tubular portion 16. Each of the ears 24, 26 and 28 has a generally trapezoidal configuration which provides a lead taper to facilitate the fit of the tubular portion 16 of the socket body into the mounting hole 22. As is conventional, the lead taper is adapted to engage the clearance slots at the perimeter of the mounting hole 22 so that the tubular portion 16 will be easily aligned for axial insertion to a point where the rear wall on each of the retention ears 24-28 will be located axially inwardly of the inner surface 32 of the panel portion 12 prior to final torque application for assembly of the light socket 10 to the light housing. As seen, the tubular portion 16 has an annular gasket 34 supported on the tubular portion 16 in abutment with the flange 30. The gasket 34 has a thickness which is adapted to produce an interference fit between the panel portion 12 and the flange 30 when the tubular portion 16 of the socket body is located within the mounting hole 22. More specifically, the gasket 34 is in the form of a ring with each side thereof provided with a plurality of equally spaced concentric and outwardly projecting circular ribs 36. As best seen in Figures 2 and 3, the ribs 36 extend outwardly from the body of the gasket 34 an equal distance so that the outer tips of the ribs are located in a common plane which is perpendicular to the longitudinal centre axis A of the tubular portion 16. During the installation of the light socket 10 to the panel portion 12, the retention ears 24-28 are first aligned with the associated clearance slots after which the light socket 10 is moved axially into the mounting hole 22 until the ears 24-28 are located axially inwardly of the inner surface 32 of the panel portion 12. The light socket 10 is then rotated to a locked position during which time the ears 24-28 pull the flange 30 towards the outer wall 38 of the panel portion 12 to compress the ribs 36 of the gasket 34 into a tightly sealed relationship with the mounting hole 22. The locked position of the light socket 10 is attained when a catch member 40 on a lock arm 42 integrally formed with the tubular portion 16 snaps radially outwardly into engagement with a lock member (not shown) located on the panel portion 12. A similar locking arrangement can be seen in US-A-4,804,343. The bulb 14 is adapted to be mounted within a retainer/ground member 44 which serves as an insert member that is insertable into and fixedly supported within an opening defined by a generally cylindrical wall 46 formed in the tubular portion 16 of the socket body. As best seen in Figures 1, 2 and 6, the retainer/ground member 44 is made of a metallic material and has a base or body portion 48 in the form of a split ring with each of the opposed facing and parallel end surfaces 50 and 52 being provided with a barb 54. The base portion 48 has a top edge 56 and a bottom edge 58 both of which are located in parallel planes positioned normal to the longitudinal centre axis of the base portion 48. In addition, the base portion 48 is formed with a pair of diametrically opposed guide channels 60 and 62 with the guide channel 60 merging with a part of a J-slot 64 in the base portion. The guide channel 62 merges with the upper portion of a part of a similar J-slot 66 located at a lower level from edge 56 than the J-slot 64. A tongue 68 depends from and is integrally formed with the base portion 48 and, as seen in Figures 5 and 6, is slightly offset radially outwardly from the outer peripheral surface of the base portion 48. The tongue 68 is planar in configuration and has the opposed sides thereof formed with identical barbs 70 located adjacent the upper end of the tongue 68. The lower end of the tongue 68 is provided with an aperture 72 and it will be noted that, as seen in Figure 5, the tongue 68 is located in a plane which is parallel to the longitudinal centre axis A of the base portion 48 and the longitudinal centre axes of the guide channels 60 and 62. When the retainer/ground member 44 is to be assembled in the tubular portion 16 of the socket body 15, the tongue 68 is initially vertically aligned with a guide channel 74 formed in the inner wall 46 of the opening of the tubular portion 16. As seen in Figure 5, the guide channel 74 is vertically aligned with a guide slot 76 located in the base of the tubular portion 16 and is positioned diametrically opposite a column member 78 which projects radially inwardly from the inner wall 46 towards the centre longitudinal axis A of the tubular portion 16. The lower end of the column member 78 terminates with a pair of shoulders 80 located on opposite sides thereof. Thus, when the retainer/ground member 44 is inserted into the opening defined by wall 46 of the tubular portion 16, the tongue 68 is guided by the guide channel 74 until it enters the guide slot 76. At the same time the opposed end surfaces 50 and 52 of the base portion 48 engage the opposed sides of the column member 78 and as the retainer/ground member 44 is moved further into the opening of the tubular portion 16, the tongue 68 continues to move into the guide slot 76 and the opposed end surfaces 50 and 52 slide along the opposed sides of the column member 78 until the lower edge 58 of the base portion 48 adjacent the opposed end surfaces 50 and 52 contacts the shoulders 80 adjacent the lower end of the column member 78 and the offset connecting part of the tongue 68 contacts the entrance end of the guide slot 76. At this point, the barbs 54 formed adjacent the top edge 56 on the opposed end surfaces 50, 52 of the base portion 48 will bite into the opposed sides of the column member 78 and the barbs 70 formed on the opposed sides of the tongue 68 will similarly bite into the side walls defining the guide slot 76, thereby to lock the retainer/ground member 44 inside the opening of the tubular portion 16. As can be seen in Figures 4, 5 and 7, the rectangular connector portion 18 is formed with three laterally spaced and parallel elongated cavities 82, 84 and 86, each of which has a longitudinal centre axis which is substantially perpendicular to the longitudinal centre axis A of the tubular portion 16. The cavities 82 and 84 serve to support a pair of identical feed terminals 88 and 90, respectively, while cavity 86 serves to house a ground terminal 92. The entrance end of each of the cavities 82-86 is circular in cross-section for a short distance into the connector portion 18 after which each of the cavities 82-86 is generally square in cross-section, as seen in Figure 5. The generally square portion of each feed cavity 82-86 extends beyond the tubular portion 16 as seen in Figure 4 and terminates at an end wall 94. More specifically, as seen best in Figures 4 and 7, each of the feed terminals 88 and 90 is made of beryllium copper and comprises an elongated narrow base plate 96 integrally formed with a pair of laterally spaced upstanding side walls 98 and 100. A cantilevered contact section 102 is reversely bent from the free end of the base plate 96 and terminates with a foot 104 which engages the base plate adjacent axially spaced pairs of crimping flanges 106. The crimping flanges 106 fixedly connect the bare wire strands of a feed cable 108 to the feed terminal while crimping flanges 110 fixedly connect a cable seal 112, having ring-type sealing ribs, to the feed cable 108. As can be seen in Figure 4, when each of the feed terminals 88 and 90 is located in its respective cavity, the reverse bend portion thereof contacts the end wall 94 of the associated cavity and the sealing ribs of the cable seal 112 serve to seal the circular entrance end of the cavity. Also, the side walls of each cavity 82 and 84 engage and support the side walls 98 and 100 of the associated feed terminal so that the latter is firmly housed within the accommodating cavity. Thus, the bowed portion of the cantilevered contact section 102 of each feed terminal is located within the inner diameter of the retainer/ground member, as seen in Figures 3, 4 and 7. The ground terminal 92 is adapted to be received by the ground cavity 86 as seen in Figures 1, 5 and 7, and has a base plate 114 which is vertically oriented and a pair of oppositely extending guide surfaces 116 and 118 which are received within opposed guide tracks formed in the generally square portion of the ground cavity 86. The ground terminal 92 terminates with a reversely bent contact foot 120 having a generally V-shaped portion which engages the aperture 72 in the tongue 68 of the retainer/ground member 44. The opposite end of the ground terminal 92 is formed with axially spaced crimping flanges 122 and 123 which, as in the case of the feed terminals 88 and 90, serve respectively to connect the strand wires of a cable 124 and a cable seal 126 to the ground terminal 92. The feed terminals 88, 90 and the ground terminal 92 are retained in the connector portion 18 of the socket body by a cable lock 128. The cable lock 128 is made from a plastics material and is integrally formed with three laterally spaced semi-cylindrical projections 130, 132 and 134 which extend outwardly from a base 136 as seen in Figures 1 and 3. Each of the outer projections 130 and 134 is formed with a slot 138 to allow outward flexing of the side portion of the wall, each of which walls is formed with an elongated opening adapted to be snapped over and mate with a tapered catch 140 integral with the connector portion 18. Thus, when the cable lock 128 is joined to the end of the connector portion 18, the projections 130-134 register with and accommodate the cylindrical outer portions of the cavities 82-86 and the side portions of the wall snap into locked engagement with the catches 140, resulting in the cable lock 128 being located on the connector portion 18 to prevent removal of the feed terminals 88, 90 or the ground terminal 92. From the above description, it should be apparent that when the various parts of the light socket seen in Figure 1 are assembled so as to provide the light socket 10 seen in Figures 3-5, the light socket 10 will be in a condition to receive the bulb 14. In this regard, the bulb 14 is a dual filament bulb and has a base provided with a double-contact so that the bulb 14 is suitable for use in automotive lights such as front and rear lights, side indicator lights, parking lights and also braking lights. The base of the bulb 14 is also provided with a pair of diametrically opposed outwardly projecting pins (one of which only is shown in Figure 1 and indicated by the reference numeral 142). The pins 142 are indexed so as to allow the base of the bulb 14 to be inserted into the retainer/ground member 44 in one rotational position only. Thus, the pins of the bulb 14 first enter the guide channels 60 and 62 until the dual contacts on the base of the bulb 14 engage the contact sections 102 of the feed terminals 88 and 90. Pressure is then applied to the bulb 14 against the spring bias of the contact sections 102, after which the light bulb 14 is rotated to cause the pins 142 to clear the separator part 144 of each J-slot 64-66. The spring force of the contact sections 102 is then allowed to raise the pins 142 into the grooves 146 of the associated J-slots and thereby to lock the bulb 14 in the retainer/ground member 44. In the locked position of the bulb 14 in the light socket 10, one of the contacts on the base of the bulb 14 is in electrical contact with one of the feed terminals 102, while the other contact is in electrical contact with the other feed terminal 102. The ground contact is provided through the pins 142 on the bulb base and the retainer/ground member 44 to the ground terminal.

Claims: A light socket for a light bulb (14), which light bulb includes a base with electrical contact means; the light socket (10) comprising an electrically insulating socket body (15) including a tubular portion (16) provided with an inner wall (46) for receiving an electrically conductive insert member (44) along a first axis, and a connector portion (18) for receiving at least one feed terminal (88,90) and a ground terminal (92) along laterally spaced parallel second axes, each of which second axes is substantially perpendicular to the first axis; the inner wall (46) including a column member (78) projecting radially inwardly from the inner wall and having a longitudinal centre axis substantially parallel to the first axis, and a guide slot (74) formed in the inner wall (46) along an axis substantially parallel to the longitudinal centre axis; the insert member (44) including a body portion (48) in the form of a split ring having opposed facing end surfaces (50,52) adapted to engage the sides of the column member (78), and a tongue (68) depending from the body portion (48) and adapted to be located in the guide slot (74) so as to provide electrical contact with the ground terminal (92); the at least one feed terminal (88,90) including a contact member (102) located within an inner periphery of the body portion (48) of the insert member (44); whereby insertion of a bulb (14) into the insert member (44) followed by rotation of the bulb (14) results in the electrical contact means of the bulb (14) engaging electrically the contact member (102) of the at least one feed terminal (88,90) and in the base of the bulb (14) engaging electrically the ground terminal (92) through the insert member (44). A light socket according to claim 1, comprising a pair of feed terminals (88,90), each of which terminals includes a contact member (102) for engaging a respective one of two contact means of a light bulb (14). A light socket according to claim 1 or 2, wherein the guide slot (74) is disposed substantially opposite to the column member (78) in the inner wall (46). A light socket according to claim 1, 2 or 3, wherein each of the opposed facing end surfaces (50,52) of the body portion (48) is provided with a barb (54) adapted to engage the column member (78). A light socket according to claim 4, wherein the barbs (54) on the opposed facing end surfaces (50,52) are disposed adjacent an end of the body portion (48) remote from the tongue (68). A light socket according to any preceding claim, wherein the body portion (48) is generally cylindrical, the tongue (68) being radially offset relative to the body portion (48) and being provided with a barb (70) on each side thereof, the barbs being adapted to engage the guide slot (74). A light socket according to claim 6, wherein the barbs (70) on the tongue are located at an end of the tongue adjacent the body portion (48). A light socket according to any preceding claim, wherein the tubular portion (16) of the socket body (15) is provided with an annular flange (30) and a plurality of ears (24-28) axially spaced from the annular flange. A light socket according to claim 8, wherein a gasket (34) is provided on the tubular portion (16) between the annular flange (30) and the ears (24-28). A light socket according to claim 9, wherein the gasket (34) is provided with a plurality of substantially equally spaced concentric ribs (38) on opposed sides thereof. A light socket according to claim 10, wherein the ribs (38) on each side of the gasket (34) extend by substantially the same amount in a direction substantially perpendicular to a centre axis of the gasket (34). A light socket according to any preceding claim, wherein the body portion (48) is formed with at least one J-shaped slot (64) for receiving a securing member (142) on the base of a light bulb (14). A light socket according to any preceding claim, wherein the contact member (102) of the or each feed terminal (88,90) is a cantilevered contact member.

Inventors: BALDWIN RONALD ALLEN, BUNGO EDWARD MARTIN, CHAPIN MELODEE ANN, COPE KENNETH PAUL, CROUSE RALPH WOODRUFF, DRAPCHO JAMES MICHAEL, BALDWIN, RONALD ALLEN, BUNGO, EDWARD MARTIN, CHAPIN, MELODEE ANN, COPE, KENNETH PAUL, CROUSE, RALPH WOODRUFF, DRAPCHO, JAMES MICHAEL
Applicants: GEN MOTORS CORP, GENERAL MOTORS CORPORATION
Application year: 1992
Main classification: H01R33
IPC codes: H01R33, F21S8, F21V19