US2671139A

US2671139A - Detecting device

Info

Publication number: US2671139A
Application number: US263435A
Authority: US
Inventors: Lee E Dilts
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1951-12-26
Filing date: 1951-12-26
Publication date: 1954-03-02
Anticipated expiration: 1971-03-02
Also published as: GB721525A

Description

March 2, 1954 1.. E. DILTS DETECTING DEVICE Filed Dec. 26, 1951 a 75 k Z8 29 35 Z 74 /5 I 26 /3 as I 24 2/ s I 34 E 33 37 /3 a Line 7 Irfivemtor: Lee E. DILLS Patented Mar. 2, 1954 ,139

UNITED STATES FATENT OFFICE DETECTING DEVICE Lee E. Dilts, South Euclid, Ohio, assignor to General Electric Company, a corporation of New York Application December 26, 1951, Serial N 0. 263,435

10 Claims. (01. 20061.42)

l 2 My invention relates to apparatus for manutained in one application of my invention by profacturing electric lamps and discharge devices, viding a group of suitably shaped feelers on a and more particularly to apparatus for detectcommon pivot and moving the pivot toward the ing the presence or absence or defective condiholder for a corresponding group of leading-in tion of Wires or wire assemblies of mounts for 5 wires or wire-like bodies to an extent which lamps and other electrical devices. causes the feelers to be rotated out of position Because of the automatic nature of stem and by engagement therewith. Preferably, a single mount making apparatus and the high speeds magnet provides the means of holding all of the of operation of such apparatus it is very desirfeelers in the test position and performs this able that some means be provided to determine function by attracting portions of said feelers. whether the wire parts have been properly fed Switching means of suitable alarm and control and assembled in the apparatus. That objective means is advanced through the position normally is attendant with certain difficulties inasmuch occupied by portions of such feelers as are not as these wire parts are relatively small and flexidisplaced by the leading-in wires or wire-like bio and usually present only a very limited area bodies. for n g m nt Wi h he cti n appar s Another object of m invention is to provide The high speed of operation, as well as the ina device for detecting the absence of a leadingherent vibration of the stem and mount making in wir in th holder of a st m making machine, pparatus, also add to the difiiculties of detectthe device being of a type suited to detect a pluing the relatively limp wire parts of this type. rality of leading-in wires in a very restricted One object of my invention is to provide apspace in said machine. To this end, means are paratus for detecting the presence or absence of provided for advancing a narrow feeler end forewire-like bodies of very slight treng h or de1 most through the position normally occupied by cate construction, which apparatus is suited to th leading-in wire or, if said wire i present, to i h Operating speeds and which is suited to use engagement therewith. Means are also provided in an automatic manufacturing machine- T s for effecting the switching of an electrical conend, I provide a feeler of low mass and mounted trol circuit should the feeler fail to engage a supfor movement against, or through the normal 110- port wire and move to the full extent of its mosition of, the wire-like body. One detecting deti vice of t general Class With Which s inVen- Further objects and features of my invention tion is concerned is disclosed in Patent 2,053,137, will appear in the following detailed description Donovan el; al., dated September 1, 1936, and asof specie thereof and from the drawing signed to the assignee of the present invention. I th drawing Fi 1 i a id levatio of a However, in prior art devices the pressure of e leading-in wire detecting device comprising my gagement of the feelers with the wire-like bodies 3 invention at the moment of its arrangement at has been cont o led by ns f Weights and operative relation to a leading-in wire holder of springs. Such means increase the test pressure a t aki ma hi i fi during the displacement of the feelers and, acfled by having the control circuit diagram sucordingly, are diincult to adiust to proper ope perimposed thereon; Fig. 2 is a plan view of the tion. The Weigh and p g type means also leading-in wire detecting device and the holder cause the feelers to oscillate back and forth when of Fig. 1; and Fig. 3 is a perspective view of a removed from engagement with the mount so that wire assembly inspecting device constructed acsuccessive cycles of operation of the device cancording to the invention and at the moment of not follow too closely. Such disadvantages are its movement into operative relation to a lamp obviated in accordance with one aspect of my inmount vention by provision of magnet means arranged The leading-in wire detecting device disclosed to control the pressure of engagement of the in Figs. 1 and 2 of the drawing is mounted befeelers. low and outward from the circular path of move- Another object of my invention is to provide ment, indicated at I, of work carrying heads a detecting device for stem machines and the like (one head being shown in part at 2), of a mawhich device is well suited to feel for groups of chine corresponding to the stem making portion the leading-5n wires wire-like bodies and which of an automatic machine for making incandoes not take a complex form in such app1icadescent lamp mounts and disclosed in Patent tions so as to be unreliable and difficult to keep 1,987,532 to Flaws, dated May 9, 1933. The dein proper operatin condition. This object is attecting device bears a definite relation to a station taken by each of the heads of the stem making apparatus in turn and preferably is located at a station following that at which the four leading-in wires 3, i, 5, and are fed into the head 2 inasmuch as the improper feeding of said leading-in wires 5, 5, and 5 will then be discovered immediately by said device. This arrangement of the leading-in wire detecting device in the stem making apparatus also enables said device to be used to control all subsequently occurring operations performed on the stem parts in the head 2 and avoids wastage of parts in that feeding operations can be by-passed.

The detecting device is so located with-respect to the station shown that the upper sensing ends I of each of four generally vertical feleers 8, 9, Iii, and H on a common pivot pin i2 are carried against, or pass through the positions normally occupied by the leading-in wires 3, 4,5, and 6 respectively, by a counter-clockwise rocking movement of the-support lever is for the pivot pin 12 about the shaft it. The feelers 8, ii, if), and H lie at a retracted pcsition to one side of the path of travel of the head 2 during the advance of said head 3 to the station and initiate the cycle of operation by being advanced to operative relation to the leading-in wires 3, 4, 5, and B in the manner described. A bracket 15 on the'upper end of fixed column 55 provides the support for the shaft It, whereas the operative functions of the device, which must be timed to the advance of a head 2 to the station, are preferably effected by means connected to the main driving means (not shown) of the stern making apparatus and effecting operation in the manner of other conventional operating means associated with said apparatus. The rocking operation of the support lever i3 is brought about by upward motion of the operating rod if under control of the operating means (not shown) and results in movement of the operatin arm it together with the support lever I3 at the beginning of the cycle inasmuch as said operating arm it, which is mounted upon the support pivot IS on said support lever I3, is maintained at a fixed relation to said support lever 13. The contraction force of the helical spring at such times causes the operating arm It to be held at a position where it bears against the end of a stop screw 2i in a raised lug on one side of the support lever 13.

As the rocking movement of the support lever l3 progresses, the sensing ends I of the feelers 8, 9, I0, and H either pass through the position of any of the leading-in wires 3, i, 5, and 6 that may be missing or butt against said wires 3, 4i, 5, and 5 so that they are pushed back and turn in a clockwise direction about pin it! (Fig. 1) to the displaced position at which they appear in the drawing. The swinging movement of the feelers 8, 9, liL'and ii is effected against the resistance furnished by the attraction of a relatively strong magnet 22 for the lower control portions 23'of each of said feelers S, 8, i0, and H on the opposit side of the pivot if from the sensing portions 1, and displaces said control portions 23 from engagement with the post 24 projecting from the side of the support lever [3. The magnet 22 provides in one body the means of controlling the position of all of the feelers 8, 9, l5, and H and exerts a controlling force determined by its adjusted position on the support lever I3.

When a greater or lesser contacting force is required of the feelers 8, 9, i0, and H, the screws 25-25 which extend through the essentially nonmagnetic support lever !3 to the nut 26 are loosened and said magnet 22 is slid toward or away from said feelers 8, 9, l0, and H, which are made of a magnetic material such as steel. The magnet 22 is adjusted to a relation to the feelers 8, 9, I5, and H to cause said feelers to seat firmly against the leading-in wires "3', 4, 5, and 8 without bending them from position and is so arranged that it retains control over said feelers 3,9, It], and Il even after they are displaced by engagement with said leading-in wires 3, i, 5, and 6.

In order to' allowtlie pressure of engagement of the feelers 8, 9,115, and ii to be as great as possible it is preferred that the device be located at an elevation causing the sensing ends 72' thereof to engage portions of the leading-in wires 3, 4, 5, and 5 immediately above a holder comprised of a fixed center jaw 2'! and a pair of separable outer jaws-28, and 29 which form wells or pockets for the retention of the lower ends of saidleading-in wires- 3, 4,. 5, and 5. The vertical extent "of the leading-in Wires 3, t, 5, and 5 which is open to engagement by feelers 8, 5, if! and H is restricted by the presence of a vitreous stem tube 35 retained bya pair of jaws 3i, and 32 at a position directly above theholder of the head 2. At the limit of'the rocking or positioning movement of the feelers 8, 9, H3, and H the support lever 13 has moved to the extent that the stud 33 on the lowerportion thereof bears against the end of the stop screwed in a clearance slot in the bracket l5.

After the feelers B, 9, l0, and H have been brought to operative relation to the leading-in wires 3, 5, and 5, the electrical switching means of said device is brought into position to be tripped thereby so that said means can effect control over an alarm or such stem making apparatus of the complete machine as it may be desirable to control thereby. The switching means is made effective when the continuing motion of the operating arm is carries the actuating blade 35 of a totally enclosed commercial form of switch 36 attached to the side thereof up against the control end 23 of such one or more of the feelers 8, 9, l0, and l l as have not been displaced by engagement with the leading-in wires 3, t, 5, and 6. This continuing motion of the operating arm 58 stretches the helical spring 20 (inasmuch as the support lever I3 is incapable of further movement) and can actuate the switch 36 when one of the feelers 8, 9, l0, and l I remains in its original position (indicated in dash-dot lines, Fig. 1) and in engagement with the locating post 25. Because the actuating blade 35 comes to bear against parts of the control portions 23 of the feelers B, 9, l0, and H located on the opposite side of the pivot pin 12 from sensing portions 1 thereof, the pressure of engagement causes said feelers 8, 9, l0, and H to be more tightly pressed against the post 24 and cannot push them from position. Movement of the actuating blade 35 of the normally open switch 36 causes said blade 35 to press the pin 35 to a position whereby the circuit therethrough is complete. Under these conditions the control circuit to the signal lamp 31 is complete and said lamp 31 is lighted and indicates a missing leading-in wire in the head 2. If other controls are to be operated by the circuit through the switch 36, they are connected in place of the signal lamp 3'! or in electrically parallel relation thereto.

Under the normal operative conditions, the next operation of the leading-in wire detecting device is to withdraw from operative relation to the head 2. This operation is effected by a downward return motion of the operating rod I 1 and thelsubsequently occurring return swing of the operating arm I8 and the support lever I3.'

Means are also incorporated in the detecting device disclosed in Figs. 1 and 2 for rendering said device incapable of performing its normal leading-in wire detecting function should" a stem tube 30 be missing from the head 2, a condition which exists when thestem making machine is being operated for warming up or at anytimewhen flare tubes 30 are not being fed into'the machine. The incorporation of 'means of this type in the detecting riding control for preventing the flashing of a warning when leading-in wires are purposelykept fromthe heads 2 stem making machine;

The missing stem tube control means performs its'overriding function according to the rotative position of a lever 10 pivoted upon pin H on the upper extremity of the support lever I3 and arranged so that presence of a stem tube 30 against the rod-like finger 12 on its upper end causes it 'to turn about said pin 1I so that the post 13 on its lower end is moved from a blocking position in front of the feelers 8, 9, I0, and I I. The lever 10 is normally under the influence of the contracting force of a helical spring 14 connected between the post 13 and a post on the support lever- I3 so that it is turned into eng'agementwith the stop screw 15 on said support lever I3, and the post 13, through engagement with the edges of the feelers 8, 9, I0, and Ii, presses said feelers to the full tilted (inoperative) position. The usual movements of the support lever I3 in advancing the feelers 8, 9, I0, and II into contact with the leading-in wires 3, 4, 5, and Ii normally cause the finger 12 to bear against the stern tube and turn the lever 10 so that the post 13 is moved away from feelers, 8, 9, I 0, and II which are then free to swing under the influence of the magnet 22 or said leading-in wires 3, 4, 5, and 6. If the finger 12 contact a stem tube 30 it of course will not be moved from the position where the post 13 on its lower end blocks movement of the feelers 8, 9, I 0, and II which will result in the actuating blade of the control switch 36 passing by and not engaging the control portions 23 of said feelers 8, 9, I0,andII.

The wire assembly inspection device shown in Fig. 3 is, like the previously described modification, arranged at a work station in automatic manufacturing apparatus and, through its ability to detect the absence or improper manufacture of certain wire-like and readily deformable parts of the incandescent lampmount 40, provides a means of automatically determining the proper operation of said apparatus. The inspection device is located at a work station taken by the mount 40 during the course of its manufacture in a machine of the type disclosed in Flaws Pattent 2,085,578, dated June 29, 1937, which is also assigned to the assignee of the present invention, and is preferably operated by the main driving means of said machine in order to cause its operative cycle to coincide withthe advance of said mount 40 to and from said workstation.

during operation of the The inspection device corresponds generally to the device disclosed in Donovan et aLPatent 2,053,137, dated September 1, 1936, in that it pro device introduces 'an over? does not H, 42, 43 and 44 upward to an vides a plurality of feelers H, 42, 43 and 44 normally located below the mount 40 and movable upward against or through the normal position of parts of said mount 40 to determine the presence or absence of said parts. The feelers M, 42, 43, and 44 are" pivoted upon a common pin 45 carried by the bifurcate ends (only one being shown) of a bracket 46 on the upper end of a rod 41. When moved upward by movement of the bracket 46 and the rod 41 under the influence of the mount making machine, the feelers 4I 44 bring their sensing end portions 48 (extending in a generally horizontal direction from said pivot pin 45) into engagement with specific portions of the mount 43. The sensing end portions 48 of the feelers H and 44 are so shaped that they are caused to bear against portions of laterally extending

tie wires

49 and 50 at points adjacent the vitreous arbor 5| of the stem 52 of the mount 43 at the same time as the sensing portions 48 of the

feelers

42 and 43 are caused to bear against portions of a coiled-coil filament 53 on opposite sides of a support wire 54 extending downward to said filament 53 from said stem arbor 5|. The

' pressure of engagement of all of the feelers 4|,

42', 43 and 44 results from control portions forces applied to the 55 thereof lying almost directly below the pivot pin 45 inasmuch as said

feelers

41, 42, 43, and 44 have relatively little mass and have a weight distribution almost balancing them about the pivot pin 45. These forces are applied to each of the feelers M, 42, 43, and 44 equally by the attraction for the control portions 55 thereof of a magnet 56 mounted upon a bar 51 of non-magnetic material connecting the bifurcate ends of the bracket 46. The extent of the vertical movement of the feelers 4!, 42, 43 and 44 carries them to a higher position than shown in Fig. 3 of the drawing and advances said feelers extent such that they are tilted about the pivot pin 45 to positions, corresponding to that indicated by the dot dash outline 55 of the control portion 55 of feeler 4I, when their respective portions of the mount 40 are engaged. On the other hand should the feelers 4|, 42, 43 and 44 fail to engage portions of the mount 40, they will remain in their initial position wherein the control portions 55 thereof are held against the sleeve 53 on a stop pin 59 extending between the bifurcate ends of the bracket 45 by the attraction of the magnet 55 for said control portions 55.

The electrical circuit controlling function of the inspection device occurs during the immediately following interval when the lever $3 is moved upward through the initial positions occupied by the control portions 55 of the feelers 4!, 42, 43, and 44 and, should the mount 49 be defective, said lever 6!] is tilted out of position by said control portions 55 so as to effect operation of the switch 55. The motion of the lever 30 is brought about by movement effected in rod 52 in manner corresponding to the movement in rod 47 and is in a vertical direction at the start of the cycle in that said lever to is keptfrom turning about the pivot pin 83 in the bracket E4 on said rod 62 by a helical spring 85 located between an ear on said bracket 64 and the lower or vertical arm of said lever 60. Should all of the feelers4l, 42, 43 and 44'l1ave been tilted by engag ment with the tie wires 49 5t and the filament 53, and the mount to be properly made so that/said

tie wires

49 and 50 and the filament 53 areretained at their proper positions therein, the

outer end'of the horizontal arm of lever will pass upward above the elevation of the ends of the control portions 55 of said feelers 4|, 42, 43 and 44; and no further action will result. However, should one or more of the feelers 4|, 42, 43, and 44 fail to have been fully displaced because of a defect in the mount .0. the said end of the lever M will be brought against the end of the control portion 55 thereof and will be tilted counter-clockwise (Fig. 3) about the pivot pin 53 so that the lower end thereof forces the control arm 58 of the switch 6| back sufficiently to actuate said switch Actuation of the switch 8|, in turn, makes an electrical circuit therethrough which may be arranged to control an indicator light and other electrical apparatus, as for instance in the manner of the previously described apparatus. The switch 6| is a stationary element of the combination fastened by the bracket 51 to the frame (not shown) of the mount making machine at a position opposite the lower end of the lever 60.

The arrangement of the feelers 4|, 42, 43 and 44 is such that they engage well supported portions of the

tie wires

49 and 50 and the filament 53 and accordingly will not bend said portions out of position even though the rate of operation of the inspection device is very rapid and said feelers 4|, 42, 43, and 44 are carried up against said portions very speedily. It should also be noted that the eifective pull of the magnet 56 for the control portions 55 of the feelers 4|, 42, 43 and 44 becomes progressively less as the control portions 55 are displaced and in some measure counterbalances the increased pressure of the feelers 4|, 42, 43, and 44 caused by the control portions 55 being swung to one side about the pivot pin 45. This construction prevents the application of considerably greater pressure by the feelers 4|, 42, 43, and 4.4 during their upward motion, and reduces the tendency of the resiliency in the several parts of the mount 40 to cause oscillation of said feelers 4|, 42, 43, and 44 about the pivot pin 45 which motion could interfere with the proper actuation'of lever 60 and switch 6 The arrangement of the

feelers

42 and 43 also permits them to detect improper conditions in the filament 53 such as those occurring when one or both ends of said filament 53 are not attached to the leading-in wires 68 and 59 of the mount 40 or when one or B8 and G5 are missing. Downward movements of the rods 82 and 41 effect the withdrawal of the inspection device from operative relation to the mount to and complete the cycle of operation thereof.

It will be understood that preferred forms of the invention have been disclosed and that the specific construction and arrangement of parts in these disclosures may be modified within the spirit and scope of the invention as defined by the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A device for detecting the presence or absence or displaced location of a wire-like body forming part of a mount structure of the class described, comprising a feeler having sensing and control portions at opposite sides of a pivot point and made at least in part of magnetic material, movable support means providing a pivot for said feeler, magnet means mounted upon the support means adjacent to said feeler and controlling the position of the feeler by magnetic attraction therefor, means for moving the support means toward th wireelike body to cause the sensing both of said leading-in wires portion of the feeler to bear therea'gainst and the control portion thereof to be displaced by the resulting rotation of said feeler in a direction away from said magnet means, and switch means including means for actuating the switch means upon failure of the control portion of the feeler to be displaced.

2. A device for detecting the presence or absence or displaced location of a wire-like body forming part of a mount structure of th class described, comprising a feeler having sensing and control portions at opposite sides of a pivot point and made at least in part of magnetic material, movable support means providing a pivot for said feeler, magnet means mounted upon the support means adjacent the path of rotation of the control portion of said feeler for positioning said feeler by magnetic attraction for said portion, means for moving the support means toward the wire-like body to cause the sensing portion of the feeler to bear against and be rotated by said body so that the control portion thereof is displaced in a direction away from the magnet means, and switch means including means for actuating the switch means upon failure of the con.- trol portion of the feeler to be displaced.

3. A device for detecting the presence or ab: sence or displaced location of a wire-like body forming part of a mount structure of the class described, comprising a feeler having sensing and control portions at opposite sides of a pivot point and made at least in part of magnetic material, movable support means providing a pivot for said feeler, a stop mounted upon the support means in the path of rotation of the control portion of said feeler, a magnet mounted upon the support means adjacent said feeler to hold said feeler by magnetic attraction at a position where the control portion thereof engagessaid stop, means for moving said support means toward the wire-like body to cause the sensing portion of said feeler to bear against and be rotated by said body so that the control portion thereof is displaced from said stop, and switch means including means for actuating the switch means upon failure of the control portion of the feeler to be displaced.

4. A device for detecting the presence or absence or displaced location of a wire-like body forming part of a mount structure of the class described, comprising a feeler having Sensing and control portions at opposite sides of a pivot point and so proportioned as to cause the control portion to take a position below the pivot point, said feeler being made at least in part of magnetic material, movable support means providing a pivot for said feeler, a sto mounted upon the support means adjacent one edge of the control portion of the feeler, a magnet mounted upon the support means adjacent the stop to attract the control portion of the feeler into engagement with said stop, means for moving said support means toward the wire-like body to cause the sensing portion of said feeler to bear against and be rotated by said body so that the control portion thereof is displaced from the stop, and switch means including means for actuating the switch means upon failure of the feeler to be displaced.

. 5. A device for detecting the presence or absence or displaced location of a wire-like body forming part of a mount structure of the class described, comprising a feeler having sensing and control portions at opposite sides of a pivot point a d so. proport on d a t cause h c rol p tion to take a position below the pivot point, said feeler being made at least in part of magnetic material, movable support means providing a pivot for said feeler, a stop mounted upon the support means adjacent one edge of the control portion of said feeler, a magnet mounted upon the support means adjacent said stop to attract the control portion of said feeler into engagement with said stop, means for moving said support means toward the wire-like body to cause the sensing portion of the feeler to bear against and be rotated by said body so that said control portion is displaced from the stop, and switch means including a member movable upward toward the pivot of the feeler and against the end of the control portion thereof to actuate said switch should said feeler remain in position against the said stop.

6. A device for detecting the presence or absence or displaced location of wire-like bodies forming parts of a mount structure of the class described, comprising a plurality of feelers each having sensing and control portions at opposite sides of a pivot point and made at least in part of magnetic material, movable support means cause the sensing portions of the feelers to bear against and be rotated by said bodies so that the control portions thereof are displaced by the resulting rotation of the feelers in a direction away from said magnet means, and switch means including means for actuating the switch means upon failure of the control portions of one or more of said feelers to be displaced.

7. A device for detecting the presence or absence or displaced location of wire-like bodies forming parts of a mount structure of the class described, comprising plurality of era having sensing and control portions at opposite sides of a pivot point and made at least in part of magnetic material, movable support means providing a common pivot for said feelers, a. stop mounted upon said support means in the path of rotation of the control portions of feelers, a magnet mounted upon cent the stop to attract the control portions of said feelers into engagement with said stop, means for moving said support means toward the wirelike bodies to cause the sensing portions of said feelers to bear against and be rotated by said bodies so that the control portions are displaced from the stop by the resulting rotation of said feelers in a direction away from said magnet means, and switch means including means for actuating the switch means upon failure of the control portions of one or more of said feelers to be displaced from the stop.

8. A device for detecting the presence or absence or displaced location of wire-like bodies forming parts of mount structures of the class described, comprising a plurality of feelers each having sensing and control portions at opposite sides of a pivot point and made at least in part of magnetic material, a support lever mounted the support means adja- 10 for pivotal movement in a vertical plane, a common pivot for said feelers on said support lever, a stop mount on said support lever adjacent the control portions of said feelers, a magnet mounted upon said support lever adjacent said stop to attract the control portions of said feelers into engagement with said stop, means for pivoting the support lever toward the wire-like bodies to cause the sensing portions of the feelers to engage and be rotated by said bodies so that the control portions are displaced from the stop by the resulting rotation of said feelers, and switch means including means for actuating the switch means upon failure of the control portions of one or more of the feelers to be displaced from the said stop.

9. A device for detecting the presence or ab sence or displaced location of wire-like bodies forming parts of a mount structure of the class described, comprising a plurality of feelers each having sensing and control portions at opposite sides of a pivot point and made at least in part of magnetic material, a support lever mounted for pivotal movement in a vertical plane, a common pivot for the feelers on the support lever, a stop mounted on the support lever adjacent the control portions of the feelers, a magnet mounted upon the support lever adjacent the stop to attract the control portions of the feelers into engagement with the stop, an operating arm pivoted upon the support lever, means for causing movement of the operating arm to pivot the support lever toward the wire-like bodies to cause the sensing portions of the feelers to engage and be rotated by said bodies so that the control portions are displaced from the stop by the resulting rotation of the feelers, and switching means mounted upon the operating arm and including means movable against the ends of any one or more 1 the control means as is not displaced from the stop for actuating said switch means.

10. In a detecting mechanism of the class described, the combination of support means, at least one feeler member pivotally mounted on said support means and substantially balanced on its pivot, at least a portion of said feeler mem her being of magnetizable material, magnet means mounted on said support means adjacent said feeler member in a position tending retain said finger member in a normal substantially balanced position by magnet attraction therefor, means for moving said support means to carry a portion of said feeler member into engagement with an article to be detected and to displace said feeler member, upon such engagement, in a direction away fro u said magnet means, and switch means 1g; operable to actuate said switch means upon failure of said feeler member to be displaced.

LEE E. DILTS. References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,053,137 Donovan et a1. Sept. 1, 1936 2,423,953 Stratton July 15, 1947 2,434,406 Herath et al. Jan. 13, 1948 2,549,296 Diets Apr. 17, 1951