US3178796A

US3178796A - Method and device for the machine assembling of crystal diodes

Info

Publication number: US3178796A
Application number: US28728A
Authority: US
Inventors: Smits Willem Frederik
Original assignee: US Philips Corp
Current assignee: US Philips Corp; North American Philips Co Inc
Priority date: 1959-05-12
Filing date: 1960-05-12
Publication date: 1965-04-20
Anticipated expiration: 1982-04-20
Also published as: DE1160110B; GB950737A; OA00795A; NL113612C; NL239128A; CH382299A

Description

April 20, 1965 w. F. SMITS 3,178,796

METHOD AND DEVICE R THE MACHINE ASSEMBLING 0F C TAL DIODES 4 Sheets-Sheet 1 Filed May 12, 1960 INVENTOR WILLEM F. SMITS AGENT A ril 20, 1965 F, SW5

METHOD AND DEVICE FOR THE MACHINE ASSEMBLING OF CRYSTAL DIODES 4 Sheets-Sheet 2 Filed May 12, 1960 INVENTOR. WILLEM F. SMITS FIG. 2

AG NT April 20., 1965 w. F. SMl-Ts METHOD AND DEVICE FOR THE MACHINE ASSEMBLING OF CRYSTAL DIODES 4 Sheets-Sheet 3 Filed May 12, 1960 INVENTOR WILLEM F. SMITS April 20, 1965 w. F. SMITS METHOD AND DEVICE FOR THE MACHINE ASSEMBLING OF CRYSTAL DIODES 4 Sheets-Sheet 4 Filed May 12, 1960 O D O 0 O O 0 O O O o O O o O O O O 0 O D O O 0 FIG.6

INVENTOR WILLEM F. SMITS AGENT United States Patent C) M 4 Claims. (ill. 29-453 This invention relates to the machine assembling of crystal diodes. Diodes of this kind are known. In a known method for manufacturing diodes substantially by hand, use is made of rods or wires each with a whisker attached thereto and rods or wires each partly surrounded by a bulb and sealed thereto, the latter being provided at one of their ends with a flat disc carrying a crystal of, for example, germanium. Such wires will be referred to hereinafter as the anode wires and the cathode wires. In order to form the said component parts into a crystal diode, in a known method which is usually carried out by hand, the cathode wire together with crystal and bulb is fixedly arranged in a holder centering this part and the anode wire with whisker is fixedly clamped in a holder slidable in the direction of the length of this wire, the arrangement being such that the said crystal is in alignment with the anode wire. The holder with its anode wire is then moved downwards, for example by manually screwing down, so that the point of the whisker comes to bear on the surface of the crystal. After the point of the whisker has contacted the surface of the crystal, it is as it were pricked into this surface by carefully screwing on further the anode holder. Subsequently, the portion of the bulb which is still open is sealed to the anode Wire. After the anode has been assembled, its electrical properties are tested. This method of assembling crystal diodes is time-consuming and the ultimate result is highly dependent upon the person carrying out the work, which is not beneficial to the loss percentage and the constancy thereof.

An object of the present invention is to provide a method and a device which permit of assembling large quantities of crystal diodes per hour with a very high and constant output, and this substantially independently of the person carrying out the work.

In the method according to the invention, this is achieved in that a wire slidable in the direction of its length and provided with a whisker is brought in an adjusting head opposite a crystal of a cathode fixedly arranged in the longuitudinal direction thereof, whereupon the whisker end of this wire is moved in the direction of its length towards the crystal and brought into contact with it so that the end of the whisker comes to bear on the crystal with a substantially constant and adjustable force. During this contact, the electrical properties over the contact area may be tested. If the measurement yields favourable results, the whisker wire is sealed to the glass bulb of the cathode while maintaining its position with respect to the crystal.

In another important embodiment of the method according to the invention, if the result of the measurement as to electrical properties is unfavourable, the anode wire with its whisker is removed from the crystal and slightly turned about its longitudinal axis and then again moved towards the crystal, whereupon another measurement may be carried out. By repeating this process several times, it may be ensured that the sealing operation takes place only when the measurement as to given electrical properties yields favourable results. It has been found that the finished product need not be tested afterwards with regard to electrical properties. As a rule, two times prick- 3,178,795 Patented Apr. 20, 1965 ing usually suffices, but the said method may be be extended, if necessary, for a third pricking operation.

A device according to the invention is of the turret type or the like having an adjusting zone, a sealing zone and a cooling zone, sealing heads being grouped at its circumference on the same pitch circle, each comprising a pair of tongs for holding the cathode portion with crystal in position, a holder for the directed and magnetic holding of a wire with whisker (anode portion) so that the crystal of the cathode portion is aligned with this wire, a device for controlled displacement of the whisker wire in the direction of its length, during which the movement is guided so that, at the end thereof, the point of the whisker comes to bear on the crystal with a force substantially constant and adjustable for each adjusting head, a device displaceable around the whisker wire in the direction of length thereof for heating the cathode and anode brought together, and abutments for receiving and giving several commands, while there are also means for testing the electrical properties of the contact between the crystal and the point of the whisker bearing thereon, before the heating device is made operative. It is possible to position the adjusting heads, instead of in a circle, into, for example, a straight line, one after another, but the turret shape is preferred for practical reasons.

The above-mentioned device is preferably designed so that it can be coupled to transport tracks on which standard holders can be conveyed. These holders are such that they can contain component parts manufactured at another area, while these component parts can be automatically taken out of the holders and placed in the machine and hence without contact by hand, the final product manufactured on the machine being replaced in a similar manner in the holders on the transport track.

The method and the device according to the invention permit of assembling large quantities of crystal diodes per unit-time with a highly divergent number of types.

In order that the invention may be readily carried into effect, one embodiment thereof will now be described in detail, by way of example, with reference to the accompanying diagrammatic drawings, in which:

FIGURE 1 shows a diagram of the method according to the invention;

FIGURE 2 shows an adjusting head provided with some detail drawings 2a to 2 FIGURE 3 shows a device for obtaining a constant pressure between the whisker and the crystal;

FIGURE 4 shows diagrammatically in what manner the anode wire slidable in a holder can be slightly turned in this holder;

FIGURE 5 is a diagrammatic view of a turret type machine equipped with adjusting heads;

FIG. 6 shows a top plan, side elevation and sectional, and front elevation and sectional view of the details of the transport holders.

In the method according to the invention, an anode wire 1 provided with a whisker 3 (FIGURE 1a) is slidably arranged in a holder 6 (FIGURE 1b), while a cathode wire 2 provided with a crystal 4 and sealed to a glass bulb or housing 5 is held in position through its bulb portion in a supporting member 7. Subsequently, the anode wire is displaced in the direction of its length (FIGURE 1c) until its whisker end comes to bear on the upper side of the crystal 4 with a force P. In this position, the electrical properties may be tested over the contact area between the whisker and the crystal. If the measurement yields favourable results, that side of the bulb sealed to the cathode wire which is still open is now sealed to the anode wire by means of a heating device while maintaining the force P (FIGURE 1f), whereupon the finished product (FIGURE 1g), after cooling, can be removed as a crystal diode from the

holders

6 and 7.

If the result of the measurement should be unsatisfactory, then according tothe invention, before the sealing operation takes place, the whisker Wire is removed from the crystal and this wire is given a small angular displacement (FIGURE 1d), whereupon the anode wire with whisker is again brought onto the crystal (FIGURE 1e). Then a similar measurement may be carried out as described with FIGURE 10. If the measurement still does not yield satisfactory results, the removal of the whisker from the crystal and the slight angular displacement of the anode wire may be repeated, if desired. There can thus be pricked and measured several times before the anode wire is sealed to the bulb.

In order to obtain the desired adjustable and preferably constant contact pressure between the whisker and the crystal, it is necessary for, the anode wire, after its whisker end has come into contact with the surface of the crystal, to be lowered over a small further distance. For' this purpose, the invention utilizes a device which will be described more fully hereinafter.

The operations above described may be carried out by means of an adjusting head, the structure of which, may be seen from FIGURE 2 showing a detailed drawing and FIGURES 2a to 2]. The following parts can be distinguished in this adjusting head: a holder 6 provided with wedge-shaped location places and a magnetic block 12 for the directed and slidable holding of an anode wire 1 in the direction of' its length, which holder is rigidly connected via

bodies

10 and 11 to a frame 8 of the adjusting head, a pair of tongs 7 for the centered supporting, of a tubular glass bulb sealed toone end of a cathode wire provided with a crystal, a pin 13 being present for receiving commands for opening and closing the tongs, (FIGURES 2a and 2b), a slidable rod 16 having an extremity17 for displacing the anode wire 1 with its whisker in the direction of its length, whichrod can perform a vertical movement by means of a lever 20 pivoted on a shaft 21 and, during this movement, is guided in a bearing 25 (FIGURE 2e), a heating device 14 slidable in the direction. of its length around the glass bulb 5 and connected to

bodies

26 and 29 of insulating material, which heating device can turn about a shaft 24 and canbe connected by means of pins 28 (in a manner notshown) to an energizing source, (FIGURES 2 and 2e). Forming part of theadjusting head is also a

rod having carriers

22 and 23 connected thereto, which rod can move in the direction of its length. by means of a cam (not shown). During the upward movement of the rod 15, the

carriers

22 and 23 cause-theextremity 17 of 'rod 16 and the heating device 14 to be moved upwards with a stroke de termined by abutments, the adjustment being such that at first the lever and the rod 16. and then the heating device are moved upwards. l The operation of this device can be explained as follows.

When the

parts

17 and 14 occupy their upper positions,

a cathode isfirst placed in the tongs 7 (FIGURES 2a and 2b). Next, the rod 15 is moved downwards so that the heating device 14 surrounds the cathode (FIGURE 20). The rod 15 is maintained in this position for a short time until an anode wire 1 with whisker is placed in the holder 6. (FIGURE 2d). Subsequently, the rod 15 is moved down further, during which movement the position of device 14 is maintained by means of. spring steel strips 27 (FIGURE 2) and the extremity 17 of the rod 16slides theanode wire downwards (FIGURE 2e). 'An abutment 31 and a set bolt 32 are adjusted so that, after the whisker point of the anode wire 1 has come into contact with the two

contact points

36 and 37 which are connected through connecting

cables

18 and 19 to a measuring device (not shown) for testing the electrical properties of the contact between the whisker and the crystal. As previously described with the method according to the invention, in the event ofa measurement yielding unsatisfactory results,

7 the anode wire with its whisker is removed from the crystal. For this purpose, the extremity 17 of rod 16 is provided with a magnet which can pull up the anode wire 1 in the wedge-shaped carriers of holder 6 upon an upward movement of rod 16. The anode wire can now be 7 given an angular displacement in a manner as shown diagrammatically in FIGURE 4, whereby the flat side of a rubber block 39 which is moved towards the anode wire and connected to a finger 38 is brought against the anode wire in the direction indicated by arrow 40a and, subsequently, the finger 38 is moved over a short distance in mounted on a table which can rotate in a stepwise manner crystal, the rod 16 can slightly sink further due to itsnat- 1 of rod 16 uponthe point of the whisker of the anode wire 1, in a further embodiment of the invention, the extremity and is turned in each case one position with respect to a frame 41. With respect to the frame 41, there can be distinguished in this turret a plurality of zones, namely: an adjusting zone A, a sealing zone B, a cooling zone C, and a zone D for the supply of anode wires and cathode wires and the discharge of the diodes ultimately manufactured on the turret.

In the adjusting zone, an anode wire is moved onto a crystal at position b. The electrical properties of this contact are tested at position 0. The whisker is lifted from the crystal at position d, while upon turning of the turret to the subsequent position the anode wire is slightly turned by means of a rubber block. Next, the

. anode wire is again brought against the crystal at position e. The cycle may then be repeated, if desired, at the positions 7, g and h. In addition, the frame of the machine is provided at the circumference of the turret with members for the electro-magnetic blocking of the described operations at the positions d to k and g to 11' respectively, as soon as a measurement as to electrical properties at position c or position I yields satisfactory results. If the proper electrical contact between the .whisker and, the crystal is still not obtained during the last measurement at k, the cathode tongs are opened at position m likewise'electromagnetically by means of a pin 19 ofthe adjusting head (FIGURE 2a) and the bulb with its cathode wire falls out of the tongs.

.In the sealing zone B, the heating device of each ad justing head is energized, the anode wire being sealed to the bulb of the cathode while maintaining the contact pressure between the whisker and the crystal which has been establishejdin the adjusting zone.

The sealed diodes are cooled inaquiet ambiance in the zone C. 7

The machine also comprises two

guide tracks

42 and 43 for the supply, and discharge oftransport holders 52 of a standard type. These holders have a plurality of apertures 54 (FIG.-6) for vertically inserting into them anode wires'with whiskers and cathode wires with bulbs, which wires are straight in themselves, the holders also having a lateral flank provided with a number of teeth 56 such that the number of teeth corresponds to the number of apertures. When placed in guide tracks 42 and 43, a driving ratchet mechanism 47 can displace the holders in these guide tracks in a manner such that for each rotation of the turret by one position theholders also move on one tooth. Active in synchronism with the transport movement of the said holders are take-over members for taking the cathode wires and anode wires out of the holders and placing them in the positions s and t of the machine in accordance with swinging movements 48 and 49 in relation to the transport holders 52 in the guide tracks 42 and 43, and also for taking diodes and any whisker wires out of the machine at the positions It and r in accordance with swinging

movements

50 and 51 shown in the figure. In conclusion, means are provided in the zone D for the electromagnetic blocking of the various operations in this zone, this blocking being active so that, if the member for taking out diodes does not function, the standard transport receives a command not to insert an anode wire or cathode wire at the position of an adjusting head which still contains a diode. The blocking is also adjusted so that, if a cathode wire is not placed in the machine, neither is an anode wire placed in the corresponding adjusting head.

What is claimed is:

1. An apparatus for assembling crystal diodes, each provided with a cathode portion and a whisker anode portion, said cathode portion being provided with a glass housing, comprising a rotatable turret having an adjusting zone, a sealing zone and a cooling zone, a plurality of sealing heads being located at the circumference of said turret, each of said sealing heads including a pair of tongs for holding said cathode portion with its crystal, a holder for said whisker anode portion whereby the crystal of the cathode portion is aligned with said whisker, a device for controlling displacement of said whisker in the direction of its length whereby the whisker comes to bear on the top surface of said crystal with a force substantially constant and adjustable for each head, a heating member displaceable about said whisker and heating said glass housing, means for testing the electrical properties of the contact and the point of the whisker bearing thereon prior to the heating member being made operative, a plurality of transport tracks adjacent to said turret, a plurality of holders adapted to be movable on said transport tracks and having the cathode portions therein, means for taking said cathode portions out of said holders and placing them in said sealing heads, and another means for taking each of said assembled crystal diodes out of said apparatus and placing them in selected holders on the transport tracks.

2. An apparatus for assembling crystal diodes as claimed in claim 1 wherein said heating member is an electrical heating device comprising heating coils.

3. An apparatus for assembling crystal diodes as claimed in claim 1 further comprising means for removing the whisker from the crystal, and a plurality of members for slightly turning said whisker about its longitudinal axis, said members only being operative if the measurement of the electric properties of the contact area. and the point of the whisker bearing is unfavorable.

4. An apparatus for assembling crystal diodes, each provided with a cathode portion and a whisker anode portion, said cathode portion being provided with a glass housing, comprising a rotatable turret having an adjusting zone, a sealing zone and a cooling zone, a plurality of sealing heads being located at the circumference of said turret, each of said sealing heads including a pair of tongs for holding said cathode portion with its crystal, a holder for said whisker anode portion whereby the crystal of the cathode portion is aligned with said whisker, a device for the controlled displacement of the whisker being provided with a slidable weight so mounted in said holder as to urge the whisker against the crystal with a force substantially constant and adjustable for each head, a heating member, means for displacing said heating member about said whisker and heating said glass housing, means for testing the electrical properties of the contact the point of the whisker bearing thereon prior to the heating member being made operative, a plurality of levers with abutments for controlling the movement of said Weight, and a spring and another weight inside said first mentioned movable weight, said other weight being slidable therein against spring pressure, the Whisker end at the lower position of said first mentioned movable weight bearing on the crystal of said cathode portion with a force substantially determined by said spring.

References Cited by the Examiner UNITED STATES PATENTS 1,833,660 11/31 Siebs 219- 2,649,560 8/53 Blair 317236 X 2,693,555 11/54 North et al. 2925.3 X 2,697,806 12/54 Gates 2925.3 X 2,757,440 8/56 Carman 2925.3 2,823,789 2/58 Henning 198-131 2,856,571 10/58 Holzemann 2925.3 X 2,984,046 5/61 Brewer 2925.19 3,047,933 8/62 Chick 2925.3

RICHARD H. EANES, JR., Primary Examiner.

THOMAS E. BEALL, LEON PEAR, WHITMORE A.

WILTZ, Examiners.

Claims

1. AN APPARATUS FOR ASSEMBLING CRYSTAL DIODES, EACH PROVIDED WITH A CATHODE PORTION AND A WHISKER ANODE PORTION, SAID CATHODE PORTION BEIND PROVIDED WITH A GLASS HOUSING, COMPRISING A ROTATABLE TURRET HAVING A ADJUSTING ZONE, A SEALING ZONE AND A COOLING ZONE, A PLURALITY OF SEALING HEADS BEING LOCATED AT THE CIRCUMFERENCE OF SAID TURRET, EACH OF SAID SEALING HEADS INCLUDING A PAIR OF TONGS FOR HOLDING SAID CATHODE PORTION WHICH ITS CRYSTAL, A HOLDER FOR SAID WHISKER ANODE PORTION WHEREBY THE CRYSTAL OF THE CATHODE PORTION IS ALIGNED WITH SAID WHISKER, A DEVICE FOR CONTROLLING DISPLACEMENT OF SAID WHISKER IN THE DIRECTION OF ITS LENGTH WHEREBY THE WHISKER COMES TO BEAR ON THE TOP SURFACE OF SAID CRYSTAL WITH A FORCE SUBSTANTIALLY CONSTANT AND ADJUSTABLE FOR EACH HEAD, A HEATING MEMBER DISPLACEABLE ABOUT SAID WHISKER AND HEATING SAID GLASS HOUSING, MEANS FOR TESTING THE ELECTRICAL PROPERTIES OF THE CONTACT AND THE POINT OF THE WHISKER BEARING THEREON PRIOR TO THE HEATING MEMBER BEING MADE OPERATIVE, A PLURALITY OF TRANSPORT TRACKS ADJACENT TO SAID TURRET, A PLURALITY OF HOLDERS ADAPTED TO BE MOVABLE ON SAID TRANSPORT TRACKS AND HAVING THE CATHODE PORTIONS THEREIN, MEANS FOR TAKING SAID CATHODE PORTION OUT OF SAID HOLDERS AND PLACING THEM IN SAID SEALING HEADS, AND ANOTHER MEANS FOR TAKING EACH OF SAID ASSEMBLED CRYSTAL DIODES OUT OF SAID APPARATUS AND PLACING THEM IN SELECTED HOLDERS ON THE TRANSPORT TRACKS.