Socket for electric part

Abstract: Contacts are positively shifted between a contact position and a release position by an operating member. The operating member is engaged by retaining elements formed on the contacts. Projections for damping sideward movement of the contacts are formed on an engagement surface of the operating member with respect to the contacts.

Description: BACKGROUND OF THE INVENTION [Field of the Invention] This invention relates to a socket for an electric part, provided with means for shifting contacts between a contact position and a release position. [Prior Art] The invention of Japanese Patent Application No. Hei 2-278461 (EP-A-0 481 727) discloses a socket including a turnable lever engageable with contacts arranged in array. In this socket, the contacts can be shifted, as a group, away from contact pieces arranged on an electric part by properly turning the turnable lever, in order to facilitate zero-insertion of the electric part. As shown in Fig. 10, however, the above conventional socket has the following problems. When the contacts 2 are repeatedly shifted by turning the lever 1 repeatedly, the contacts 2 are horizontally displaced along their engagement surfaces with respect to the lever 1, and contacting portions of the contacts are likewise displaced. As a result, reliable contact relation is adversely affected. Moreover, if the amount of side displacement is significant, it gives rise to another problem of short-circuit between adjacent contacts 2. US-A-4,993,955 discloses a socket for an electric part, having the features of the preamble of Claim 1. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a socket for an electric part, in which contacts can be shifted between a contact position and a release position in an expeditious manner. The present invention provides a socket for an electric part, in accordance with Claim 1. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of a socket for an electric part according to one embodiment of the present invention; Fig. 2 is a perspective view of the socket of Fig. 1 from which a cover member is already removed, or a socket having no cover member; Fig. 3 is a perspective of the socket particularly showing, in an enlarged scale, retaining elements of contacts and an engaging portion of an operating member; Figs. 4A through 4C are sectional views for explaining the sequence of action of the operating member and shifting states of one of the contacts; Fig. 5 is a front view of the operating member; Fig. 6 is a sectional view taken on line A-A of Fig. 5; Fig. 7 is a front view showing another example of the operating member; Fig. 8 is a sectional view taken on line B-B of Fig. 7; Fig. 9 is a sectional view showing a state of engagement between the operating member and the retaining elements of the contacts; and Fig. 10 is a sectional view showing a state of engagement between an operating member and retaining elements of contacts according to the prior art. DETAILED DESCRIPTION OF THE EMBODIMENT One embodiment of the present invention will be described in detail with reference to Figs. 1 through 9. As apparent from Figs. 1, 2, etc., a socket for an electric part has an electric part accommodation portion 12 opening to an upper surface of a base member 11 which is formed of an electric insulating material. The socket also has a lead support seat 15 located at an inner bottom of the accommodation portion 12, the lead support seat 15 adapted to support a number of leads 13a projecting sideward from two sides or four sides of an electric part represented by an IC 13. The socket further has a number of contacts 16 arranged in array along two sides or four sides of the accommodation portion 12. Each contact 16 includes a support base portion 16' having a spring portion 16b, and a contacting portion 16a formed on an upper end of the support base portion 16' and projecting inwardly therefrom. The contacting portion 16a is supported by the support base portion 16' such that the former is held in an upper position of the lead support seat 15. As shown in Fig. 4A, when the IC 13 is not accommodated in the accommodation portion 12, in other words, when the leads 13a are not supported on the support seat 15, the support base portion 16' is shifted forwardly and inwardly together with the contacting portion 16a by elastic force of the spring portion 16b, in order to cause the contacting portion 16a to be abutted against an upper surface of the lead support seat 15, thereby allowing the spring portion 16b to store a predetermined amount of elastic force. As shown in Fig. 4B, when the support base portion 16' is shifted backwardly and outwardly against the elastic force of the spring portion 16b, the contacting portion 16a is separated to a position where it will not interfere with the lead support seat 15 and the leads 13a to be supported on the seat 15. In that separated state, the IC 13 is inserted into the accommodation portion 12 with no-load, and the leads 13a are supported on the support seat 15. Furthermore, as shown in Fig. 4C, after the insertion of the IC into the accommodation portion 12, the support base 16' of the contact 16 is shifted inwardly by restoring force of the spring portion 16b, so that the contacting portion 16a is pressure contacted with the upper surface of the lead 13a. The socket of the present invention comprises an operating member 17 formed of an electrically insulating portion as means for shifting each contact 16 backwardly, and a cover member 18 likewise formed of an electrically insulating material as means for activating the operating member 17. This operating member 17 is a means for applying backward tensile force to the contacts 16. The operating member 17 is formed of a turnable member or a reciprocating member. Figs. 2, 4, etc. respectively illustrate an example in which the operating member 17 comprises a turnable lever. As shown, the turnable lever as the operating member 17 is horizontally displaced behind the support base portions 16' of the contacts 16 along the row of the contacts 16. This operating member 17 is disposed in the vicinity of an upper end of the support base portion 16' (i.e., in the vicinity of the contacting portion 16a). Shafts 17a respectively disposed at both ends of the operating member 17 are rotatably supported by a base member 11 at both ends of each row of the contacts 16. An engagement groove 17b extending in parallel relation with each row of the contacts 16 is formed in an inner end of each operating member 17. A pressure receiving end 17c extending in parallel relation with each row of the contacts 16 is provided to an outer end of each operating member 17. Each contact 16 further includes a retaining element 16c formed of a hook member. This retaining element 16c is provided in the vicinity of the upper end of the support base portion 16'. Preferably, the retaining element 16c projects backwardly from that area of the upper end of the support base portion 16' from where the projecting portion 16a projects forwardly. For retaining, this retaining element 16c is engaged in the engagement groove 17b of the operating member 17 and hooked on an acting end 17d defining the engagement groove 17b. The retaining element 16c is contact engaged with a surface (engagement surface) of this acting end 17d. As shown in Fig. 4B, when the pressure receiving end 17c of the operating member 17 is turned downwardly from a standby position shown in Fig. 4A, in order to cause the acting end 17d to turn upwardly, a tensile force is applied to the retaining element 16c while the latter is sliding on the engagement surface. As a result, as mentioned hereinabove, the support base portion 16' is shifted backwardly so as to bring the contacting portion 16a into a position where the contacting portion 16a will not interfere with the corresponding lead. On the contrary, each contact 16 is shifted forwardly by restoring force thereof. During the forward shifting motion of the contact 16, the retaining element 16c applies a tensile force to the acting end 17d to cause the operating member 16 to turn to the standby position shown in Fig. 4A. Then, as shown in Fig. 4C, when the operating member 16 is turned generally to the end of its turning motion, the contact 16 is pressure contacted with the upper surface of the corresponding lead 13a. A plurality of projections 17e adapted to damp the contacts are formed on the surface (i.e., engagement surface with which the retaining element 16c is engaged) of the acting end. The projections capable of contacting an under surface of the retaining element 16c have such a function as to reduce slide resistance of the retaining element 16c, while the projections adjacent to a side edge of the retaining element 16c have such a function as to restrain side displacement of the retaining elements 16c. The projections are scattered like a large number of dots, although not shown. As apparent from Figs. 3, 5 and 7, the projections 17e are formed of ridges 17f extending in a normal direction with respect to the shifting direction of the contacts, and the ridges 17f are arranged in parallel relation with each other. As shown in Fig. 5, a top of each ridge 17f has a flat surface in section. As shown in Fig. 7, each ridge 17f has a sharp ridge line at a longitudinal central portion thereof and forms a watershed with reference to this ridge line 17h. As shown in Figs. 6 and 8, the engagement surface of the acting end 17d is defined as an arcuate surface in section. The projections 17e and the ridges 17f are formed on this arcuate surface in order to facilitate a smooth vertical sliding. In either case, the ridges 17f are arranged in parallel at spaces smaller than that between adjacent retaining elements 16c. In other words, as shown in Fig. 9, the retaining elements 16c are never dropped between adjacent ridges 17f under any circumstances, and at least a part of the retaining elements 16c are placed on the surfaces of the ridges 17f while the remaining retaining elements 16c extend over grooves 17g between adjacent ridges 17f, so that when the retaining elements 16c are moved sideward therefrom, they are unavoidably limited by a longitudinal side edge or ridge line of each ridge 17f adjacent thereto. Owing to this damping action, side displacement is restrained. Since the ridges 17f extend in a normal direction with respect to the shifting direction of the contacts 16, the retaining elements 16c are normally oriented in a normal direction during the shifting process of the contacts 16 by the longitudinal side edge or ridge line of each ridge 17f. At the same time, the retaining elements 16c are caused to slide in a vertical direction. As a consequence, each contact 16 can be shifted forwardly and backwardly in a correct attitude. Therefore, each contact is effectively prevented from being horizontally displaced or being twisted. As a result, the operating member becomes possible to fully exhibit its function. As described above, the cover member 18 having an opening corresponding to the accommodation portion 12 is disposed above the base member 11 such that the cover member 18 is capable of moving upwardly and downwardly relative to the base member 11. As shown in Fig. 4B, upon depression of the cover member 18, the pressure receiving end 17c of the operating member 17 is pushed down. By this, the acting end 17d is caused to turn upwardly, the contacts are pulled, and each contacting portion 16a is caused to be separated away from the corresponding lead of the contacting portion 16a. As shown in Fig. 4C, when the depressing force to the cover 18 is removed, the contact 16 is restored forwardly. Owing to this restoring force, tensile force is applied to the acting end of the operating member 17 so as to turn the pressure receiving end 17c upwardly which, in turn, pushes up the cover member 18. During the horizontal turning process of the operating member 17, the projections as represented by the ridges 17f damp the sideward movement of the retaining elements 16c. Thus, harmful side displacement can be prevented, and the retaining elements 16c are guided to slide vertically so as to contact the corresponding leads properly. In a modification of the invention, instead of the turnable lever, a slider (not shown) capable of reciprocating forwardly and backwardly may be used as the operating member. In that case, the retaining elements 16c can be drawn by the reciprocal motion of the slider. The pressure receiving end 17c may be turned by manual operation without using the cover member 18, Partition walls 14 formed on the base member 11 are interposed between adjacent contacts 16 in order to isolate the individual contacts, the contacting portions 16a of the contacts are allowed to project inwardly of the partition walls 14, and the retaining elements 16c are allowed to extend outwardly of the partition walls 14. The projections 17e as represented by the ridges 17f prevent the retaining elements 16c from displacing sidewardly, the partition walls 14 restrain side way motion of each contact 16 in the vicinity of the contacting portion 16a, and both the projections 17e and partition walls 14 are cooperated with each other in order to shift the contacts 16 in correct attitudes. In the embodiments described above, the operating member 17 is engaged with the retaining elements 16c extending backwardly from the support base members 16' of the contacts 16. However, the present invention is not limited to this. For example, in the case where the ridges and dot-like projections are arranged on the engagement surface of the operating member 17 at spaces smaller than the pitch between adjacent contacts, the present invention is likewise applicable to at least two kinds of contacts having different pitches. As described in the foregoing, according to the present invention, the projections as represented by the ridges formed on the engagement surface of the operating member favorably damp the sideward movement of the contacts while smoothly shifting the contacts forwardly and backwardly, thereby effectively preventing harmful side displacement and twisting, thus making it possible to obviate the problems of short-circuit between adjacent contacts and irregularity of contact position attributable to side displacement and twisting. As a result, highly reliable contact relation is ensured. Therefore, the function of the operating element can be exhibited effectively.

Claims: A socket for an electric part, having a plurality of contacts (16) arranged, in array, on a body (11) thereof and adapted to be contacted with contacting pieces on the electric part, said contacts (16) each including a contacting portion (16a) adapted to make pressure contact with a corresponding one of said contacting pieces and a spring portion (16b) adapted to exert a contact pressure to said contacting portion, wherein said socket body (11) is provided with an operating member (17) adapted to engage with retaining elements (16c) of said contacts so as to cause said contacting portions (16a) thereof to be shifted away from the electric part against elastic force of said spring portion (16b) of said contact, said operating member (17) being provided, at an engagement surface thereof with respect to said contacts, with a plurality of projections (17e) adapted to damp the sideward movement of said contacts, characterized in that said projections (17e) comprise ridges (17f) arranged in parallel at spaces smaller than that between adjacent retaining elements (16c), with the lower surfaces of the retaining elements (16c) being in contact with the upper surfaces of the projections (17e). A socket for an electric part as claimed in Claim 1 wherein said engagement surface is defined as an arcuate surface in section. A socket for an electric part as claimed in Claim 1 or Claim 2, wherein said ridges (17f) extend in a normal direction with respect to a shifting direction of said contacts. A socket for an electric part as claimed in any one of Claims 1 - 3, wherein said ridges (17f) each have a sharp ridge line. A socket for an electric part as claimed,in any one of Claims 1 - 4, wherein said operating member (17) is a turnable lever. A socket for an electric part as claimed in any one of Claims 1 - 4, wherein said operating member (17) is a turnable lever, said turnable lever being engaged by said retaining elements (16c) formed on said contacts (16), said projections (17e) being formed on an engagement surface of said turnable lever engaged by said retaining elements. A socket for an electric part as claimed in any one of Claims 1 - 6 wherein said projections (17e) are spaced apart from each other at a spacing narrower than the width of said retaining elements (16c).

Inventors: MATSUOKA NORIYUKI, MATSUOKA, NORIYUKI
Applicants: YAMAICHI ELECTRONICS CO LTD, YAMAICHI ELECTRONICS CO., LTD.
Application year: 1993
Main classification: H05K7
IPC codes: H01R33, H01R13, H05K7