Bulb socket and terminal installed thereon

Abstract: A cathode terminal (11), to be mounted on a bulb socket (10), comprising a first connection strip (20) which is elastically connected with the cathode of a mouth piece of a bulb (13); and a second connection strip (21) to be connected with a connector. The cathode terminal has a locking portion (26) formed at the leading end thereof by bending said cathode terminal so as to cover the upper end of said opening of said terminal inserting groove. Laterally projecting locating pins of the bulb cannot therefore be inserted into the cathode terminal inserting groove.

Description: The present invention relates to a bulb socket and a terminal installed on the bulb socket for use in the light of an automobile and more particularly to a cathode terminal installed on the bulb socket and electrically connected with the cathode of the bulb. In this kind of bulb socket, a metal plate is bent to form a cathode terminal 1 to be connected with a socket 2 as shown in Figs. 20 and 21. The cathode terminal 1 is cut in the vicinity of one end thereof in the configuration of U to project a strip elastically therefrom. Thus, a connection strip 1a to be connected with a bulb 3 is formed. A connection strip 1b to be connected with a connector is formed on the other end of the terminal 1. As shown in Fig. 14 the terminal 1 is inserted into a sectionally T-shaped groove 2c formed on the peripheral wall 2b of a bulb inserting hole 2a of the socket 2. The leading end of the connection strip 1a projecting inward from the inserting groove 2c contacts the cathode surface of a mouth piece 3a of the bulb 3 inserted into the bulb inserting hole 2a. An anode terminal 4 is inserted into an anode terminal inserting groove 2d opposed to the cathode terminal inserting groove 2c. A connection strip 4a of the anode terminal 4 is connected with the anode disposed on the bottom surface 3d of the bulb 3 and the other connection strip 4b of the anode terminal 4 is connected with the connector. Pins 3b and 3c projecting from the peripheral surface of the mouth piece of the bulb 3 are inserted downward into J-shaped pin inserting grooves 2e and 2f, respectively formed on the peripheral wall 2b of the socket 2. Then, the bulb 3 is rotated to mount it on the socket 2. The pin inserting grooves 2e and 2f formed on the peripheral wall 2b of the socket 2 are opposed to each other so that the position of each of the pin inserting grooves 2e and 2f corresponds with the position of each of the pins 3b and 3c of the bulb 3. That is, the peripheral wall 2b of the socket 2 has four inserting grooves formed therein, namely, the groove 2c for receiving the cathode terminal 4 opposed to the groove 2d for receiving the anode terminal 1 and the pin inserting grooves 2e and 2f opposed to each other. The inserting grooves 2c and 2d are approximately T-shaped in sectional view and open in a small width on the inner surface of the peripheral wall 2b. The inserting groove 2c has a width large enough for the connection strip la to project inward while the width of the inserting groove 2d is very small. The pin inserting grooves 2e and 2f are sectionally U-shaped and has a width large enough for the pins 3b and 3c to be smoothly inserted thereinto. More specifically, the width of the pin inserting grooves 2e and 2f is larger than that of the opening of the inserting groove 2d for receiving the anode terminal and smaller than the outer diameter of the pins 3b and 3c. Accordingly, the pin 3b or the pin 3c cannot be inserted into the inserting groove 2d because the width of the inserting groove 2d is small. However, the socket 2 is easily deformed, i.e., the width of the opening portion of the inserting groove 2d becomes larger because it is made of resin. As a result, the pin 3b or 3c may be inserted into the inserting groove 2d. As described above, the pins 3b and 3c are opposed to each other. Therefore, the other pin 3b or 3c is inserted into the inserting groove 2c. As a result, the spring of the terminal is deformed, thus pressing the pin 3b into a portion below the connection strip 1a of the cathode terminal 1 and consequently, the pin 3b is caught by the connection strip 1a. Therefore, the bulb 3 cannot be taken out from the socket 2. If the inserting grooves 2c and 2d are not opposed to each other, it is necessary that the configuration of the terminals are complicated and dimension accuracy cannot be obtained, and hence manufacturing cost is high. In addition, supposing that the pin 3b or the pin 3c of the bulb 3 is inserted into the terminal inserting groove 2c or 2d, the pin 3b or the pin 3c is brought in contact with the inner surface, of the peripheral wall of the bulb inserting portion, which is not a groove-formed position but the socket 2 is deformed outward because the socket 2 is made of resin. As a result, the pin 3b or 3c is pressed into the inserting grooves 2c or 2d. Consequently, the bulb 3 is erroneously inserted into the socket 2. Thus, even though the configurations of the terminals are complicated and the inserting grooves 2c and 2d are not opposed to each other, an erroneous insertion of the pin 3b or 3c into the inserting groove 2c or 2d cannot be effectively prevented. It is an object of the present invention to provide a bulb socket and terminals to be installed on the bulb socket in which each pin of a bulb can be prevented from being inserted into each terminal-inserting groove of the bulb socket. It is another object of the present invention to provide a bulb socket and terminals to be installed on the bulb socket in which a cathode terminal having an improved construction can be reliably held without contacting an anode terminal even though the cathode terminal is moved from a predetermined position due to vibrations. Therefore, the generation of a short circuit can be prevented. In accomplishing this and other objects, there is provided a cathode terminal, to be mounted on a bulb socket, formed by bending a metal plate comprising a first connection strip projecting from a terminal inserting groove formed on a peripheral wall of a bulb inserting hole of the bulb socket and being elastically connected with the cathode of a mouth piece of a bulb; and a second connection strip to be connected with a connector, characterised by said cathode terminal having a locking portion formed at a trailing end thereof by bending over said cathode terminal so that said locking portion covers an upwardly directed opening at the end of said terminal inserting groove when said cathode terminal is installed on said bulb socket by inserting said cathode terminal located at said opening thereof downward into said terminal inserting groove. It is preferable that a bead is formed on the locking portion formed on the leading end of the cathode terminal so as to increase the strength thereof. According to the above construction, the locking portion is formed by bending the trailing end of the cathode terminal to be installed on the socket and the opening of the terminal inserting groove of the socket is closed. Therefore, the pins of the bulb can be prevented from being inserted into the terminal inserting groove. Since the locking portion has a simple construction and can be formed by only bending the trailing end of the cathode terminal, the cathode terminal can be manufactured at a low cost. These and other objects and features of the present invention will become clear from the following description taken in conjunction with the preferred embodiments thereof with reference to the accompanying drawings, in which: Fig. 1 is a sectional view showing a bulb socket and a cathode terminal applied thereto according to a first embodiment of the present invention; Fig. 2 is a plan view showing the bulb socket in which the bulb of Fig. 1 is not mounted; Fig. 3 is a front view showing the cathode terminal to be applied to the bulb socket of Fig. 1; Fig. 4 is plan view of the cathode terminal of Fig. 3; Fig. 5 is a partially enlarged perspective view showing the cathode terminal of Fig. 3; Fig. 6 is a partially enlarged plan view showing the state in which the cathode terminal is mounted on a terminal inserting groove; Fig. 7 is a sectional view showing a bulb socket and a cathode terminal applied thereto according to a second embodiment of the present invention; Fig. 8 is a sectional view of the bulb socket taken along the line II-II of Fig. 7; Fig. 9 is a front view showing the cathode terminal shown in Fig. 7; Fig. 10 is plan view of the cathode terminal of Fig. 9; Fig. 11 is a left side elevation of Fig. 10; Fig. 12 is a front view showing a conventional cathode terminal; Fig. 13 is plan view of the cathode terminal of Fig. 20; Fig. 14 is a sectional view showing a problem of a case in which the conventional cathode terminal is installed in a bulb socket. Before the description of the present invention proceeds, it is to be noted that like parts are designated by like reference numerals throughout the accompanying drawings. A first embodiment of the present invention is described below with reference to Figs. 1 through 6. A bulb socket 10, a cathode terminal 11, an anode terminal 12, and a bulb 13 to be installed on the socket 10 have the same construction as that of the conventional one except the construction of the cathode terminal 11. The method for installing the cathode terminal 11, the anode terminal 12, and the bulb 13 on the socket 10 is also similar to the conventional method. Sectionally T-shaped terminal inserting grooves 10c and 10d are formed in opposition to each other on the peripheral wall 10b of the socket 10. The peripheral wall 10b surrounds a bulb inserting hole 10a of the socket 10 consisting of molded synthetic resin. The cathode terminal 11 and the anode terminal 12 are inserted downward into the terminal inserting groove 10c and the terminal inserting groove 10d, respectively. A connection strip 20 integral with the cathode terminal 11 is connected with the cathode (A) of a mouth piece 13a of the bulb 13 to be inserted into the bulb inserting hole 10a. The other connection strip 21 integral with the cathode terminal 11 is connected with a connector (not shown) to be inserted into a connector inserting opening 10e of the socket 10. Similarly, a connection strip 12a of the anode terminal 12 is connected with the anode (B) of the bulb 13 and the other connection strip 12b thereof is connected with the connector. The cathode terminal 11 and the anode terminal 12 are inserted into the terminal inserting groove 10c of the socket 10 and the terminal inserting groove 10d thereof, respectively and then, the bulb 13 is installed on the socket 10. That is, J-shaped pin inserting grooves 10f and 10g are formed in opposition to each other on the peripheral wall 10b of the socket 10 with a certain distance spaced from the terminal inserting grooves 10c and 10d, respectively. Pins 13b and 13c projecting in opposition to each other from the peripheral surface of the mouth piece 13a are inserted into the pin inserting grooves 10f and 10g, respectively. When the pins 13b and 13c reach the lower end of the pin inserting grooves 10f and 10g, respectively, the bulb 13 is rotated. As a result, the pins 13b and 13c are fixed thereto. As a result, the bulb 13 is fixed to the socket 10. A metal strip in the configuration of a narrow band is bent as shown in Figs. 3 and 4 to form the connection strip 20 to be connected with the cathode of the bulb 13 and the connection strip 21 to be connected with the connector. The center portion of the uppermost or trailing end 25 of the cathode terminal 11 positioned at the upper end of the opening of the terminal inserting groove 10c is bent to form a locking portion 26. The locking portion 26 is bent in the direction same as the direction in which the connection strip 20 is bent. As shown in Fig. 6, the length L1 of the locking portion 26 is a little smaller than the dimension L2 of a narrow-width portion 10c-1 of the opening of the terminal inserting groove 10c, and the width W1 of the locking portion 26 is approximately equal to the width W2 of the narrow-width portion 10c-1. Accordingly, the opening of the terminal inserting groove 30c is covered with the locking portion 26 when the cathode terminal 11 is installed on the socket 10. It is preferable that a bead portion 27 is formed on the locking portion 26 of the cathode terminal 11 so as to improve the strength thereof. Since the locking portion 26 is formed on the trailing end of the cathode terminal 11, the locking portion 26 covers the upwardly directed opening at the end of the terminal inserting groove 10c when the cathode terminal 11 is inserted into the terminal inserting groove 10c as shown in Fig. 1. Therefore, if the pin 13b is to be erroneously inserted into the terminal inserting groove 10c in inserting the bulb 13 into the bulb inserting hole 10a, the pin 13b is brought in contact with the locking portion 26. Thus, the pin 13b cannot be inserted into the terminal inserting groove 10c. A smoothly curved portion 22 is formed in the vicinity of leading end of the connection strip 20 of the cathode terminal 11 so that the curved portion 22 serves as the contact point between the connection strip 20 and the cathode of the mouth piece 13a of the bulb 13. Thus, a metal plated on the mouth piece 13a can be prevented from being separated therefrom. In addition, a projection 23 disposed inward of the connection strip 20 projects from the cathode terminal 11 toward the center of the socket 10 so that the projection 23 is locked by the bottom surface of the bulb 13. Thus, the bulb 13 prevents the cathode terminal 11 from being moved or removed from the terminal inserting groove 10c so that the cathode terminal 11 does not contact the anode terminal 12. Thus, the generation of a short circuit can be prevented. As apparent from the foregoing description, according to the first embodiment, the locking portion is formed by bending the trailing end of the cathode terminal to be installed on the socket and the opening of the terminal inserting groove of the socket is closed. Therefore, the pins of the bulb can be prevented from being inserted into the terminal inserting groove. Since the locking portion has a simple construction and can be formed by only bending the trailing end of the cathode terminal, the cathode terminal can be manufactured at a low cost. A second embodiment of the present invention is described below with reference to Figs. 7 through 15. A bulb socket 30, a cathode terminal 31, an anode terminal 32, and a bulb 33 to be installed on the socket 30 have the same construction as that of the conventional one except the construction of the cathode terminal 31. The method for installing the cathode terminal 31, the anode terminal 32, and the bulb 33 on the socket 30 is also similar to the conventional method. Terminal inserting grooves 30c and 30d are formed on the peripheral wall 30b of the socket 30. The peripheral wall 30b surrounds a bulb inserting hole 30a of the socket 30 consisting of molded synthetic resin. The cathode terminal 31 and the anode terminal 32 are inserted downward into the terminal inserting groove 30c and the terminal inserting groove 30d, respectively. Locking strips 40 and 50 integral with the cathode terminal 31 and the anode terminal 32, respectively are locked by locking grooves 30e and 30f, respectively formed on the socket 30. In this manner, the cathode terminal 31 and the anode terminal 32 are installed on the socket 30 at a predetermined position thereof. At the installed position of the cathode terminal 31 and the anode terminal 32, a connection strip 41 disposed on one end of the cathode terminal 31 is connected with the cathode (A) of the mouth piece 33a of the bulb 33 to be inserted into the bulb inserting hole 30a, and a connection strip 42 disposed on the other end of the cathode terminal 31 is connected with a connector (not shown) to be inserted into a connector inserting opening 30g of the socket 30. A narrow-band metal strip is bent and partially cut to form the cathode terminal 31 in the configuration as shown in Figs. 9 through 11. That is, a strip integral with a narrow-band base plate 45 (shown in Figs. 9 through 11) elastically projects therefrom in the vicinity of one end (left end of base plate 45) thereof along the center line in the widthwise direction thereof to form the connection strip 41. The leading end of the connection strip 41 projects toward the center of the socket 30 in mounting the cathode terminal 31 on the socket 30 and is curved to form a smoothly curved contact 41a. A projection 43 is formed by bending and projecting a part of the base plate 45 at a right angle therewith from approximately the center thereof. The width of the projection 43 is approximately the half of the width of the base plate 45. Similarly to the connection strip 41, when the cathode terminal 31 is mounted on the socket 30, the projection 43 faces toward the center of the socket 30 and the surface of the leading end of the projection 43 serves as a locking surface 43a for locking the bulb 33 as will be described later. The locking surface 43a projects horizontally directly below the socket 30 when the cathode terminal 31 is mounted on the socket 30 as shown in Fig. 7. The projection 43 extends toward the other end of the base plate 45 and projects in the direction in which the base plate 45 is bent to form the projection 43. Thus, a base portion 46 of a connection strip 42 to be connected with the connector is formed. In addition to the locking strip 40, a projection 47 extending in the peripheral direction of the socket 30 is formed in parallel with the locking strip 40 on the base portion 46 so that the width of the base portion 46 of the connection strip 42 is equal to or slightly smaller than the width of the upper end of the opening of the cathode terminal inserting groove 30c. The projection 47 and the base plate 45 are disposed in the same plane. The leading end of the base plate 45 is bent to form a locking portion 48 on the cathode terminal 31 so that when the cathode terminal 31 is inserted into the terminal inserting groove 30c of the socket 30, the opening of the terminal inserting groove 30c is covered with the locking portion 48. Thus, the pin of the bulb 33 cannot be erroneously inserted into the opening of the terminal inserting groove 30c. The locking strip 40 of the cathode terminal 31 is locked by the locking groove 30e formed alongside the opening 30h for receiving the connection strip 42 to be connected with the connector when the cathode terminal 31 is mounted on the socket 30. In this condition, the connection strip 41 contacts the cathode surface of the mouth piece 33a of the bulb 33 and the locking surface 43a of the projection 43 positioned below the connection strip 41 is disposed below the bottom surface of the mouth piece 33a of the bulb 33. In this condition, the anode terminal 32 does not contact the cathode terminal 31 and thus a short circuit is not generated. When the cathode terminal 31 is disengaged from the locking strip 40 as a result of vibrations imparted to the automobile as shown in Figs. 7 and 8, the projection 43 disposed directly below the bottom surface of the mouth piece 33a moves upward and as a result, the locking surface 43a thereof contacts the shoulder of the bottom surface of the mouth piece 33a. Thus, the cathode terminal 31 is held in this condition. The base portion 46 of the cathode terminal 31 does not contact the lower surface of the connection portion 51 of the anode terminal 32 at the cathode terminal-held position. Therefore, the cathode terminal 31 does not contact the anode terminal 32 and thus the generation of a short circuit can be prevented. The projection 47 is provided in a lower portion of the cathode terminal 31, namely, on the base portion 46 of the connection strip 42. Thus, the cathode terminal 31 has a large width in the vicinity where the projection is formed. Since the cathode terminal 31 is inserted into the terminal inserting groove 30c of the socket 30 from the large-width portion thereof, the cathode terminal 40 is inserted thereinto at a right angle with the upper end of the opening of the inserting groove 30c. The projection 43 is formed on the cathode terminal 31 for the locking surface 43a to prevent the cathode terminal 31 from being removed from the socket 30 owing to the contact between the locking surface 43a and the bottom surface of the mouthpiece 33a of the bulb 30. Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications are apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims unless they depart therefrom.

Claims: A cathode terminal (11,31), to be mounted in a bulb socket (10,30) formed by bending a metal plate comprising; a first connection strip (20,41) projecting from a terminal inserting groove (10c,30c) formed on a peripheral wall (10b,30b) of a bulb inserting hole (10a,30a) of said bulb socket and being elastically connected with the cathode (A) of a mouth piece of a bulb (13,33) and a second connection strip (21,42) to be connected with a connector, characterised by said cathode terminal having a locking portion (26,48) formed at a trailing end (25) thereof by bending over said cathode terminal so that said locking portion covers an upwardly directed opening at the end of said terminal inserting groove when said cathode terminal is installed on said bulb socket by inserting said cathode terminal located at said opening thereof downward into said terminal inserting groove. A cathode terminal as claimed in claim 1, characterised in that a bead portion (27) is formed on the locking portion (26) to strengthen the locking portion (26).

Inventors: MATSUMOTO MASAYOSHI, OGAWA SHINJI, MATSUMOTO, MASAYOSHI, OGAWA, SHINJI
Applicants: ICHIKO INDUSTRIES LTD, SUMITOMO WIRING SYSTEMS, ICHIKOH INDUSTRIES LIMITED, SUMITOMO WIRING SYSTEMS, LTD.
Application year: 1992
Main classification: H01R33
IPC codes: H01R33, H01R13