US 3167981 A
Description (OCR text may contain errors)
United States Patent Ofitice Y 3,167,981 Patented Feb. 2, 1965 ration of California Filed Nov. 8, 1961, Ser. No. 151,031 3 Claims. (Cl, 81-43) This invention relates to tweezers and more particularly to a tool of this type which has a reverse action.
Tweezers having reverse action are typically complicated mechanisms which are expensive of manufacture and unsuited for the handling of small articles such as small jewels and crystals. Conventional tweezers of the type wherein the gripping force is exerted upon the object being held by the tweezers only while a gripping force is exerted upon the arms of the tweezers are particularly unsuited for use in handling very small articles, since a slight relaxation of the gripping force by the operator allows the small article to fall from the grip of the tweezers. That is, by conventional action in tweezers it is meant that the tweezer is in an open position in its normal or relaxed state and is in a gripping position with the ends or points of the tweezers coming together only when the operator exerts a squeezing or compressive force upon the arms of the tweezer. In handling small articles such as electronic components, minute wires, and crystals of the type used in semiconductor devices, it can be seen that it is very easy to drop such an article of this size from the tweezer, since it is necessary only to slightly relax the force to allow the gripping points of the tweezer to come apart by the small extent necessary to allow the articles to be dropped from the grip of the tweezers. In the semiconductor industry, for example, it is often necessary to lift and transport very fine components, such as fine wires and crystals of germanium or silicon whose greatest dimension does not exceed .030". I
Accordingly, it is a primary object of the present invention to provide an improved reverse action tweezers which is simple and economical of manufacture and efficient in use.
It is another object of the present invention to provide such a reverse action tweezer which will exert a uniform gripping force upon small or minute objects in the relaxed condition of the tweezers and will be opened sufiiciently to release or re-grip such a small article by a slight pressure of the operator upon the arms of the tweezers.
It is another object of the present invention to provide a reverse action tweezers which is simple in design and economical of manufacture.
The novel features which are believed to be characteristic of the present invention both as to its organization and method of operation, together with further objects and advantages thereof will be better understood from the following description considered in connection with the accompanying drawing in which a presently preferred embodiment of the present invention is illustrated by way of example only and is not intended as a definition of the limits of the invention.
In the drawing:
FIGURE 1 is a view in perspective of the presently preferred embodiment of the tweezers of this invention;
FIGURE 2 is a top plan view of the tweezers as shown in FIGURE 1;
FIGURE 3 is a side view in elevation of the tweezers;
FIGURE 4 is a side view in elevation similar to FIG- URE 3, but showing the tweezers in the position at which they are manipulated to the open condition; and,
FIGURE 5 is a view in cross-section taken along line 55 of FIGURE 4.
Referring now to the drawing, there is shown in FIG- URE 1 a presently preferred embodiment of the reverse action tweezers of the present invention in the normal or relaxed state thereof at which the end points 10 and 11 which comprise the gripping points or jaws of the tweezer are together in compression with a sufficient compressive force to grip any small object such as a semiconductor crystal. The tweezers consist of two resilient arms 12 and 14 which are similar in construction and which are connected at the rear as at 15. Similar to tweezers of the prior art, the tweezer arms 12 and 14 diverge from the closed end 15 which is connected by any conventional means such as riveting, soldering, brazing, or the like. As shown particularly in FIGURE 3, the closed end 15 of the tweezers extends throughout a portion of the length of the assembled tweezers, as, for example, to the point 16 at which the arms commence their divergence. From the point of divergence 16 to the ends of the tweezers at 10 and 11, the interior surfaces 17 and 18 of the tweezer arms are generally concave in curvature. The exterior surfaces 19 and 20 of the tweezer arms 12 and 14, respectively do not however follow a smooth line of curvature but are, rather, reduced in thickness throughout a substantial portion of their length. Thus, as shown particularly in FIGURES 23 and 24, there is a region at the exterior surface of each of the tweezer arms 12 and 14 designated as regions 21 and 22 which are regions of decreased thickness relative to the overall thickness of the tweezer arms. The regions 21 and 22 of reduced thickness extend from a point such as 2111 and 22a to 21b and 22b. The points 2111 and 22a are located a slight distance forwardly of the point of divergence 16 while the points 21b and22b are located a slight distance from the ends 10 and 11 of the arms 12 and 14, respectively. The distance by which points 21a and 22a are spaced from point 16 is approximately equal to the distance by which points 21b and 22b are spaced from the ends 10 and 11. The regions 21 and 22 of reduced thickness accordingly extend throughout a substantial portion of the divergent part of the tweezer arms 12 and 14. The regions of decreased thickness are approximately concave toward the interior surfaces 17 and 18 of the tweezer arms such that a point of minimum thickness occurs approximately midway between the points 21a and 21b and 22a and 22b, respectively. The tweezer arms are formed of a resilient spring steel which can be deformed but which returns to a normal relaxed condition. The relaxed condition of the arms is such that the spring force of the arms will urge the points 10 and 11 together.
Referring now particularly to FIGURES 3 and 5, there is affixed to one of the tweezer arms only a fulcrum pin 25. In the presently preferred embodiment of the tweezers as illustrated, the fulcrum pin 25 is affixed to the upper tweezer arm 12. Thus, as shown in FIGURE 5, the fulcrum pin 25 is afiixed to the interior surface 17 of the fulcrum arm 12 by means of a rivet or the like 26 which is extended through the tweezer arm. The fulcrum pin 25 is of predetermined length and is preferably rounded at its outer end 27. The length of the fulcrum pin 25 is predetermined such that it bears against the interior surface 19 of the opposite tweezer arm 14 when the points 10 and 11 of the tweezer are in compressive engagement due to the resilient action of the tweezer arms. The fulcrum pin 25 is located at a position rearwardly of the points 21b and 22b of the tweezer arms and is thus spaced a substantial distance from the ends 10 and 11 of the tweezers. The length of the fulcrum pin 25 and its exact longitudinal positions for optimum operation of the tweezers can be readily determined by one skilled in the art in view of the present disclosure. The pin is located and is of such length relative to the construction of the tweezer arms that a compressive force applied to the tweezer arms 12 and 14 rearwardly; i.e., toward the end 15, will cause the tweezer arms to be fulcrumed about the pin 25 such. that the ends10 and 11 f the tweezers are forced apart. That is, referring now to FIGURE '4, the reduced thickness sections 21 and 22 of the tweezer arms having their thinnest portion rearward of the fulcrum pin 25 will allow the interior surfaces 17 and 18 of the lever arms to be forced together rearwardly of the pin when a compressive forceat that point is applied by the operator as shown in FIGURE 4. Thus, when the operator squeezes upon the tweezers at a position rearwardly of the fulcrum pin 25-, the lever arms are pivoted about the fulcrum 25 causing the ends and 11 to be separated by a substantial distance. Upon relaxation of the compressive force at the point rearward of the pin 25, the nat:
ural resiliency of the tweezer arms 12 and 14 will cause them to assume their normal or relaxed condition at which thepoints 10 and 11 of the tweezers are again urged together in compression. U
Thus, it can be seen that the tweezers in accordance with the present invention can be utilized to transport or manipulate minute articles by squeezing upon the tweezers rearwardly of the fulcrum pin 25 to thereby open the tweezers; When the compressive force caused by the fingers of the operator is relaxed, the points will close upon thesmall object such as the semiconductor crystal and will hold it firmly in place within the; tweezers.- The hold upon the small object will be maintained until a similar compressive force is again exerted at the point rearwardly of the fulcrum pin.- Thus, a small object being carried willremain within the tweezers and it.
is not necessary for the operator to continually exert a pressure force as in convention tweezers.
What is claimed is:
1 A reverse action tweezer comprising first and sec ond' spaced apart resilient arm members connected together at one end thereof and provided a pair of gripping jaws at the opposite end thereof; the interior surfaces of'said arm members being generally concave in curvature, a longitudinally extending section of reduced extending from a point spaced from the connected end to a point spaced from the gripping end of said tweezer arms, a fulcrum pin affixed to one of said arms and extending fromthe interior surface of said first arm to the interior surface of the oppositearm and being in nonafi-ixed bearing contact, with; said opposite arm at the normal relaxedcondition of s'aid-tweezer arms.
2. Areverse; action tweezer comprising first and second juxtaposed arm members of resilient material, said arms being longitudinally extending and joined at the first end thereof, saidarms being normally in bearing engagement at the second end thereof to form gripping jaws, a region of reduced thickness of said arm members intermediate saidfirst and second ends, a fulcrum pin atfixed'to the first of said arm members and extending into non-afiixed bearing engagement with the second of said arm members, said fulcrum pin being positioned between said second end of said armsand the mid-point of'said regions of reduced thickness,
3. A reverse action twee'zer comprising'first and second juxtaposed arm members. of'resilient material, said arms being longitudinally extending and joined at the first end thereof, said arms being normally in bearing engagement at the second end thereof'to form gripping jaws, a region of reduced thickness formed in each of said arms,.said regionbeing longitudinally extending from a firstpoint spaced. from said'first end toa second point spaced from said.second end, a fulcrum pin afiixed to said firstle'ver arm and extending into non-afiixed'bearing contactwith said second arm when said second ends are in bearing engagement, said fulcrurn'pin being longitudinally spaced from said first end and proximate said first point.
References Citedb'y the Examiner,
UNITED STATES PATENTS 759,668 5/04 Carlseni. 8143 2,207,930 ,7/40 Miller' 81-43 2,943,521; 7/60; Bettont t 8143 WILLIAM FELDMAN, Primary Examiner. L A..- SCHEEL, Examiner.