US3282397A

US3282397A - Apparatus for feeding articles

Info

Publication number: US3282397A
Application number: US505442A
Authority: US
Inventors: Peter M Grunwald
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1963-06-04
Filing date: 1965-09-01
Publication date: 1966-11-01
Anticipated expiration: 1983-11-01

Description

Nov. 1, 1966 P. M. GRuNwALD 3,282,397

Nov. l, 1966 P. M. GRUNWALD 3,282,397

APPARATUS FOR FEEDING ARTICLES Original Filed June 4, 1963 8 Sheets-Sheet 2 Nv. 1, 1966 P. M. GRuNwALD 3282397 APPARATUS FOR FEEDING ARTICLES original Filed June 4, 1963 8 sneet-sheet s 'Nv.1.1966 RMGRUNWALD g 3,2s2,397

APPARATUS FOR FEEDING ARTICLS Original Filed June 4, 1963 8 Sheets-Sheet 5 v 103 v o) N ,3

Nov. 1, 1966 P. M. GRuNwALD APPARATUS FOR FEEDING ARTICLES original Filed June 4, 1963 8 Sheets-Sheet 6 ol' l .2. 4 M A Nov. 1. 1966 P. M; GRuNwALD APPARATUS FOR FEEDING ARTICLES 8 Sheets-Sfieet 7 Original Filed June 4, 1963 Nov. 1, 1966 P, M. GRUNWALD APPARATUS FOR FEEDING ARTIGLES 8 Shee'cs-Shee1'I 8 Original Filed June 4, 1963 United vStates Patent O 3,282,397 APlPARATUS FOR FEEDING ARTICLES Peter M. Grunwald, Zurich, Switzerland, assignor to Western Electric Company, Incorporated, New York, N.Y., a corporation of New York Original application June 4, 1963, Ser. No. 285,438', now Patent No. 3,240,332, dated Mar. 15, 1966. Divided and this application Sept. 1, 1965, Ser. No. 505,442 11 Claims. (CI. 198-33) This application is a division of application Serial No. 285,438 filed June 4, 1963, now Patent No. 3,240,332 issued March 15, 1966.

This invention lrelatesflto apparatus for feeding articles and, more particularly, to apparatus for feeding and orienting articles having surfaces of differing characteristies. v

In the mass production of many articles, the articles are processed through several areas, a particular operati-on or series of Operations being performed at each area. For example, in the mass production of transistors, a

slice of semiconductor material having a plurality of pairs` of rectangular, metallic contacts or stripes disposed thereon is diced to form a plurality of minute wafers, each wafer being a square approximately 30 mils X 30 mils with a thickness of 4 mils and having a pair of contacts on one of its surfaces. The wafers are then bonded to individual headers having a pair of post-like terminals, after which individual leads are bonded to each contact and to a corresponding header post. In order to facilitate the lead bonding Operation, it is desirable that each wafer be bonded to its header in a manner such Ithat each of its contacts is in a predetermined relationship to its corresp-onding terminal. Accordingly, this necessitates that each wafer be presented to the wafer bonding area in a predetermined orientation.

Heretofore, such orientation has been accomplished inanual-ly, the operator selecting a wafer from a bulk supply of randomly ar-ranged wafers, positioning it to a desired orientation and then depositing it into a magazine or carrier. Obviously, performing these s-teps on a fully manual basis is time consuming and not compatible with mass production techniques. Accordingly, there is .a need for mechanized apparatus which will select wafers from a bulk supply, feed them to an orienting station and discharge the oriented wafers into a magazine or, if desired, directly to another machine for subsequent Operation thereon.

It is an object of this invention to provide new and improved apparatus for feeding articles.

It is another object of this invention to provide new and improved apparatus for feeding and orieuting articles having surfaces of differing Characteristics.

It is a further object of this invention to provide new and improved apparatus for feeding and orienting articles having surfaces of different light refiectivity Characteristics.

I-t is still another object of this invention to provide new and improved apparatus for feeding and orienting minute articles, such as semiconductor wafers, having a surface marking.

' It is a still further object of this invention to colloca-te initially randomly arranged articles into a single row of substantially dimensionally correct articles.

Apparatus for feeding and orienting .articles having surfaces of differing characteristics illustrating certain features of the invention may include means for receiving such articles, arranging them seriatim, and advancing the seriatim arranged articles along a predetermined path of travel to sensing means. The sensing means inspects a surface of the articles exposed thereto and senses a characteristic of the surface. Means responsive to the sensing 3282397 Patented Nov. 1, 1966.

means are provided for distin-guishing surfaces of a first type characte-ristic from those of va second type characteristic and for ejecting from the series of advancing articles each of the articles which has been presented to the sensing means with a surface of the second type characteristic exposed for inspection. Accordingly, each of the remaining articles of the advancing series has the surface thereof with the first type characteristic facing in a common direction. Means disposed in the path of travel of the remaining articles areprovided for selectively engaging and rotating an individual article to position the article in a desired angular orientation in the plane of the surface of the first type, characteristic.

In one illustrative embodimen-t of .the invention the articles arewafer-like and are received by and advanced along a track having an inclined sidewall and an adjoining base projecting laterally from the bottom of the sidewall. The width of Ithe base along a first section thereof is wide relative :to the thickness of a single article and the articles are advanced along this section in a random arrangement; that is, some articles may travel edgewise with a surface thereof contacting the sidewall; other articles may travel with a surface thereof contacting the base; and still others may travel a-top -or alongside other articles. In order to colloca-te the articles seriatim, the width of the base along a second segment thereof is narrowed so as to support only a single article, thereby precluding an article from traveling with one of its surfaces superimposed on the surface of another. The sidewall, along a section thereof commensnrate with or subsequent to the narrowing of the base, has a slant he-ight sufiicient to support only a single article, thereby precluding an article from traveling with one of its edges supported upon an edge of another article. In this manner, the articles are formed into a single row for presentation to the sensing means.

According to one aspectof the invention, where the difference in surface characteristics includes a difference in surface light refiectivity, the sensing means includes a light source and a photoelectric device arranged with respect to the track such that as an article is advanced into registration with the light source and an Opening provided in the track sidewall, light is reflected from the article and directed to the photoe-lectric device. The photoelectric de- Vice is connected -to a circuit which is functional upon an article being presented to the sensing means with a surface of one type reflectivity in facing relationship theret-o, to cause a stream of -fluid to .be passed through the sidewall Opening to eject the article from the track.

According to another aspect of the invention the engaging and rotating means include a rotatable member selectively movable into engagement with an article to be oriented. Selective rotary motion is imparted to the member by connecting it to a motor having means associated therewth for controlling the motion thereof in accordance with a desired angular orientation of the article. To this end the controlling means is provided with a plurality of selectively actuable time delay circuits, the time delay of ea-ch circuit corresponding to the time required for the motor to rotate through a particular angle.

Other objects and advantages of the invention will be more readily understood from the following detailed description when considered in conjunction With the accompanying drawings wherein:

FIG. lI is a fragmentary, perspective view of article feeding and orienting apparatus embodying certain principles of the invention with portions thereof broken away and removed for purposes of clarity;

FIG. 2 is a fragmentary front elevation view of the apparatus of FIG. 1 with portions thereof removed for purposes of clarity; i

FIG. 3 is an enlarged, perspective view of a semicon- 3 ductor wafer which may be fed and oriented with the apparatus of FIG. 1; 1

FIG. 4 is an enlarged, fragmentary, perspective view taken along the line 4-4 of FIG. 2 with parts thereof broken away and removed for purposes of clarity;

FIG. 5 is an enlarged, fragmentary, perspective view taken along the line 5-5 of FIG. 2 with parts thereof broken away and removed for purposes of clarity;

FIG. 6 is a schematic diagram of a photoelectric circuit for testing the surface Characteristics of articles;

FIG. 7 is a schematic diagram of an article accumnlation control circuit;

FIG. 8 is an enlarged, fragmentary, perspective view taken along the line 8-8 of FIG. 2 of an orienting station according to the invention with parts thereof broken away and removed for purposes of clarity;

FIG. 9 is an enlarged, fragmentary, perspective view taken along the line 9-9 of FIG. 2 of an orientor according to the invention with parts thereof broken away and removed for purposes of clarity;

FIG. 10 is an enlarged, plan view illustrating the possible orientations an article, such as a semiconductor wafer, can occupy in a channel forming a part of the feeding and orienting apparatus;

FIG. 11 is a schematic diagram of a photoelectric circuit for determining when a magazine used with the feeding and orienting apparatus is fully loaded;

FIGS. 12 and 13, combined, constitute a schematic diagram of an electrical control circuit embodying certain principles of the invention;

FIG. 14 is a diagrammatic view showing how FIGS. 12 and 13 are arranged to complete the electrical circuit.

Referring now to the drawings, there is shown in FIG. 1 an apparatus for feeding and orienting articles having surfaces of differing Characteristics, Isuch as semiconductor wafers -20, which includes a circular vibratory feeder, designated generally by the numeral 21, and a linear vibratory track, designated generally by the numeral 22.

Typically, as shown in FIG. 3, each wafer 20 is a square 30 x 30 mils with a thickness of 4 mils and comprises a main body portion 23, composed of silicon, which is provided with an integrally formed mesa 24 having a base contact 26 and an emitter contact 27 alloyed to the top surface thereof. Additionally, as a result of the manufacturing process, the top surface of the wafer, i.e., the surface containing the emitter and base contacts, is polished and hence, is of a higher reflectivity than the bottom surface.

The circular feeder 21 is of the conventional type, and includes a vertical bowl 28 having a horizontally extending dish-shaped loading portion 29 Secured to its lower extremity for receiving the wafers 20-20, the dish extending underneath the initial portion of the linear track 22 for reasons which will become readily apparent from the discussion which follows. The bowl 28 is constructed with a spirally inclined track 31 around its outer periphery, which communicates with the loading dish 29 at its lower end and an exit chute 32 at its upper end. Provided with the bowl 28 is a base unit 30 (FIG. 2) which contains an electromagnetic drive for imparting Vibrations to the bowl in a manner which causes the wafers 20-20 to move radially inwardly of the bowl and in a circular path along its outer periphery. Thus, when the drive unit is actuated, the wafers 20-20 deposited on the loading dish 29 move radially inwardly of the bowl and up the spiral track 31 to the exit chute 32, whereupon they fall onto the linear track 22.

As seen in FIG. 2 the linear track 22 is supported for vibratory movement by a pair of angularly disposed, tuned springs 33-33 connected at their upper ends to the track 22 and at their lower' ends to a support member 34. Vibratory motion is imparted to the track in a conventional manner by an electromagnet 36, mounted on the support member 34, coacting with an armature 37 projecting from the underside of track 22. Upon energization of the electromagnet 36, a downward force is exerted on the armatu're 37 which causes the springs 33-33 to fiex and move the track 22 downward in an inclined arcuate path. De-energization of the electr-omagnet 36 allows the springs 33-33 to return the track to its normal position. As a result of the vibratory motion imparted to the track 22, linear movement from left to right, as viewed in FIG. 1, is imparted to the wafers 20-20 thereon. Optimum feeding of the wafers 20-20 along the track 22 is accomplished by tuning the springs 33-33 to vibrate the track at a frequency substantially equal to the frequency of the electromagnet energizing means, in the present instance, 60 cycles. The distance advanced by each wafer 20 during each cycle is a function of the mass of the wafer and the amplitude of the vibratory motion imparted to the track 22.

As best seen in FIG. 4 the entrance end portion of the track 22 is of a generally V-shaped cross-section and includes a wide inner sidewall 38 inclined at a preferred angle of approximately 45 with the horizontal and having a narrow -base 39 extending orthogonally therefrom. The width of the base 39 along a first segment 3951, located beneath the chute 32, is large relative to the size of a wafer 20 to facilitate the reception of wafers from the chute 32 to the track 22. As the wafers 20-20 fall from the chute 32, some land and remain on the segment 3941, while others land thereon and drop off as a result of their momentum. These latter wafers are directed to the loading dish 29 by a guide member (not shown) and are subsequently re-fed to the track 22.

The wafers are advanced along the segment 39a in a random arrangement. For example, some wafers, such as wafers 2011, may travel with one of their surfaces contacting the segment 39a; others, such as wafers 201), may travel edgewise with a surface contacting the sidewall 38, and still others may travel atop or alongside other wafers, such as wafers 20c` and 20d respectively. In order to collocate the wafers 20-20 into a single row, the width of the base 39 along a second segment 39b is narrowed so as to accommodate only wafers traveling with one of their surfaces contacting the sidewall 38, that is, the width of the second segment 39b is equal to the thickness of a single wafer. As a result, all wafers, traveling along the segment 39b, other than those which travel with a surfacei-contacting the sidewall 38, such as wafers 20b and 20c, fall off the base 39 onto the loading dish 29.

In order to remove the wafers 200 from the track 22 and thereby form a single row of wafers 20-20, an opening 40 is providedin the sidewall 38, which is larger than a single wafer 20 and is located at a distance from the base which is approximately equal to a peripheral dimension -of the Wafer. Thus, the wafers 200 as they reach Opening 40, fall ther-ethrough and down a passageway 42 communicating therewith. Upon exiting from the passageway 42, the wafers fall by gravity onto the loading dish 29.

The wafers 20-20, after -being fo-rmed into a single row, are screened to eliminate oversize and undersize wafers, as well as wafer chips, particles and the like which might interfere with proper Operation of the apparatus. Oversize wa-fers 20-20, that is, wafers that are larger than a desired size, in this instance 30 x 30 mils, are eliminated by a nitrogen Stream which is introduced into the track 22 from a conventional source (not shown) through an opening 43 located in the sidewall 38, the Opening being located at a distance from the base 39 which is slight-ly greater than the upper tolerance limit of the peripheral dimension of a wafer 20. Thus, wafers 20-20 which are equal to, or less than the desired size pass under the nitrogen stream, while those which are larger than the desired size, are contacted by the Stream and are blown from the track 22. Undersize wafers, as well as chips and parti-cles, are eliminated by an Opening 44 in the sidewall 38 of the track 22 which extends upaasaee? wardly from the base 39 and is smaller heightwise than the desired wafer size. The height of the' Opening is increased at its end 46 in order to accommodate chips and particles which have a dimension equal to, or greater than, either peripheral dimension of a wafer 20. The width of -this enlarged Opening is smaller than either peripheral dimension of a wafer 20 to preclude good wafers -from falling therein. The wafers `or chips which fall into Opening 44 drop down a chute 46 and into a reject receptacle (not shown) located adjacent to the track.

After -screening, the wafers are advanced to a surface testing station, designated generally by the reference numeral 47 (FIG. 5), whereat those wafers which are advanced with their top surface, i.e., the surface containing the

contacts

26 and 27, contacting the sidewall will be -blown off the track. The station includes an Opening 48 located in the sidewall 38 and communicating with a conventional source of pressurized nitrogen (not shown) under control of a solenoid 49 (FIG. 6) of a solenoid operated valve (not shown). The station 47 is further provided with a housing 51 located adjacent track 22 and connected to the support member 34 by any suitable means, such as a bracket 52 (FIG. 2). A photocell 53 and a light source 54 are disposed angularly With respect to each other in the housing 51 such that as a wafer passes over the Opening 48 the light from source 54, which is arranged so as to irradiate the entire wafer in this position, is refiected to the photocell 53.

The amount of reflected light received by the photocell 53 is dependent upon which surface of the wafer, i.e., top or bottom, is presented to the light source, the top surface, since it is polished, refiectng more light than the lbottom surface which is relatively dull. Since the resistance of the photocell 53 is inversely proportional to the amount of light incident thereon, that is, the resistance of the photocell decreases as the incident light increases, the difference between the light reflected from the upper surface of the wafer and that reflected from the bottom surface manifests itself as a difference in the photocell resistance.

To determine the resistance of photocell 53' and, hence, to determine which surface of the wafer is presented to the light source 54, the photocell is connected in the circuit of FIG. 6 as one arm of a bridge network, designated generally by the numeral 56. The arm adjacent to the photocell 53 is provided with a variable resistor 57 and the arms opposite thereto are provided with D.C. voltage sources 58 and 58' respectively. Each source is of equal magnitude, V, with the negative terminal of source 58 connected to the positive terminal of source 58' and to ground. Accordingly, a positive voltage, +V, appears at point 59 of the bridge 56 and an equal negative voltage, -V, appears at a point 61 thereof. As is readily apparent, if the resistance of photocell 53 is equal to the resistance of variable resistor 57, the point 62 intermediate the resistor 57 and the photocell 53 will be at zero or ground potential. However, if the resistance of photocell 53 is greater than that of the resistor 57, a voltage of positive polarity will appear at point 62 and, conversely, if the resistance of photocell 53 is less than that of resistor 57, a voltage of negative polarity will appear at point 62.

The point 62 is connected to the base 63 of a transistor 64, the collecto-r 66 of the transistor being con- Ynected to a suitable source of positive D.C. voltage,

e.g., point 59, and the emitter 67 thereof fbeing connected through a resistor 68 to ground and to the gate element 69 of a silicon controlled rectifier 71. The rectifier 71, in turn, is serially connected to the nitrogen control solenoid 49. An A.C. voltage, from a source 72, which may be 115 volts, 60 cycles, is impressed across the rectifier 71 and solenoid 49.

In Operation, the bridge 56 is calibrated by adjusting the resistor 57 so that if a wafer is advanced to the station 47 with its bottom surface presented to the larnp 54 .a positive voltage will appear at point 62, and, if a wafer is .advanced to the station with its top surface presented to lamp 54, a negative voltage will appear at point 62. Thus, when a wafer is advanced with its bottom surface presented to the lamp 54, a positive voltage appears at point 62 and, hence, at the base 63 of the transistor 64, resulting in the transistor being turned ON. In turn, this causes a gating signal to be applied to the silicon controlled rectifier 71 which results in this unit being turned ON during the positive half cycle of the applied A C. signal. As a con-sequence, energizing current is passed through the solenoid 49. Upon energization of the solenoid 49 a nitrogen stream 4is introduced through the opening 48 to blow the wafer off the track 22, whereup-on it falls by gravity to the loading dish 29. A diode 73 and a series resistor 74 are connected across the solenoid 49 to maintain a current fiow through the solenoid during the negative half cycle of the applied A.C. signal, since the rectifier 71 is turned OFF during this interval.

When a wafer is advanced to the station with its top surface presented to the lamp 54, a negative voltage appears at the base 63 of the transistor 64 which precludes the transistor 64 a-nd, hence, the silicon controlled rectifier 71 from Ibeing turned ON, Thus, no energizing current is passed through the solenoid 49 to act-uate the nitrogen stream, and the wafer remains on the track 22.

After surface testing, the base 39 comes lto an abrupt end (FIG. 5) causing the remaining surface-matched wafer 20-20 to slide down the sidewall 48 to a horizontal channel, designated generally by the reference numeral 76. The channel 76 includes a horizontal base 77 having a width just suflicient to accommodate a single wafer 20 and opposing equally inclined sidewalls 78-78' which extend upwardly from the base and terminate at respective lands 79 and 79', the sidewall 78 at the point of track transition being a continuation of the sidewall 38. The height of the sidewalls 78 and 78' is made slightly greater than the dimensionally correct thickness of a single wafer for reasons which will be discussed in greater detail hereinbelow.

Most of the surface-matched wafers 20-20, -as they fall from the base 39 land on the base 77 in a horizontal position with their top surface facing upwardly. However, .some wafers, due to the manner in which they fall, may land edgewise on the base 77 and interfere with proper ,Operation of the apparat-us. Accordingly, to remove these wafers from the track, alongitudinal slot 81 of a Width larger than the thickness of a single wafer is provided in the base 77. As a result, those wafers which ride edgewise on the base fall through the slot 81 and down a chute (not shown) which returns them to the loading dish 29.

After falling into the channel 76, the wafers 20-20 proceed seriatim therealong to an Orienting station, designated generally tby the reference numeral 82 (FIGS. l, 8 and 9). which as will be described in more detail hereinbelow is provided with means for selectively arresting the movement of the wafers to enable wafers to be fed individually into and -Out of the orienting station. As a result, the-re is a possibilty that the wafers 20-20 by virtue of their momentum may climlb over one another and thereby upset their tops facing -upwardly and serial arrangement.

In orde-r to prevent this Occurrence, a pair of cover plates 83-83 is provided for the channel 76 which extends from a point starting with the rearward end of the slot 81 (FIG. 5) to the entrance of the orienting station 82. Thus, since the height of the channel 76 is approximately equal to the dimensionally correct thickness of a single wafer, the cover plates 83-83 preclude the wafers from climbing Over one another.

In the event wafers are not of the correct thickness i.e., too thick or too thin, jams in the channel 76 might arise since the wafers which are too thick may not fit under the cover plates 83-83 and those which are too thin may clim=b over one another. To enable these jams to lbe easily cleared by an operator, a small gap is provided inte-rmediate the cover plates 83-83.

It has been observed that when wafers are fed along a fiat horizontal track of the vibratory type at a low rate setting of the vibrator, they feed sluggishly and when they are fed at a higher rate setting they feed erratically resulting in a loss of control. This problem lis obviated in the instant ap-paratus by providing a longitudinal groove 84 in the -base 77. This groove, it has been found, allows the wafers to be fed rapidly without any loss of control. It is ibelieved that the reason for the foregoing lies in the relationship between the weight of a wafer 20 and its surface area contact with the base along which it is being fed: that is, it is believed that 4the ratio of the weight-to-surface area contact of a wafer with the base is determinative of the speed at which the wafer will be fed for a given rate setting of the vibrator and that the higher this ratio the smaller the vibrator feed rate has to be in order to achieve a given wafer speed. Accordingly, by decreasing the surface area contact of a wafer with the track base 77, for exarnple, by providing the groove 83, the weight-to-area ratio of the wafer is increased and the wafer can be fed rapidly at a relatively low vibrator rate setting without loss of control.

Referring now to FIG. 2, the wafers, before entering the orienting station, pass over a photocell 85 disposed beneath the base 77 and communicating therewith through a suitable Opening 86. The function of the photocell 85 is to deactuate the vibratory drive of circular feeder 21 (FIG. 12) when a predetermned number of wafers has accumulated in front of the orienting station 82 ready for feed thereto. In this manner, a continuous row of wafers 20 20 is precluded from being formed in the channel 76 along a portion thereof which is not covered by the cover plates 83-83; since, if this were to occur, climbing of the wafers might result with the attendant disadvantages previously mentioned.

The photocell 85 is connected in the circuit of FIG. 7 as one element of a voltage divider circuit 87 which includes a resistor 08 and a D.C. voltage source 89. When ambient light irnpinges on the photocell 85, it assumes a first value of resistance resulting in an input signal of a first value being applied to a conventional time delay amplifier 91 to energize a relay 92 in the output thereof, hereinafter referred to as the accumulation control relay. A normally open contact 92a (F-IG. 12) of the relay 92 is connected in the drive circuit of the circular feeder 21 and, when closed, enables actuation thereof, the contact remaining closed as long as light impinges on the photocell 35. However, when the light to the photocell 85 is blocked, the photocell assumes a second value of resistance, higher than the first, resulting in a lower amplifier input signal, which, if maintained at this value for a time interval equal to, or greater than the amplifier time delay, will cause de-energization of the relay 92 to deactuate the drive of circular feeder 21. This latter condition occurs when a predetermined number of wafers accumulate in front of orienting station 82 with a plurality thereof disposed over the photocell 85 for a time interval equal to, or greater than the amplifier time delay.

Referring now to orienting station 82, which is best illustrated in FIGS. 8 and 9, it will be seen that two functions are performed at the station when the wafers 20 20 are presented thereto: first, the wafers 20--20 are inspected to determine Whether they have any defects or fiaws, those wafers which are considered defective being rejected. Second, the wafers 20 20 are inspected to determine their orientation, those wafers which are of undesirable orientations being rotated to a desirable one.

As seen in FIG. 10, a wafer as it enters the station 82 can be in any one of four orientations, as determined by the position of its emitte-r contact 27. It is assumed, for purposes of illustration in the present invention, that the desired orientation of the wafer for a subsequent operation, such as lead bonding, is an orientation where the emitter contact 27 is located on the left hand side of the wafer. It is apparent, therefore, that the wafer with the designated 0 orientation in FIG. 10 is the wafer depicting the desired orientation, and that the others are of undesirable orientations and, accordingly, must be rotated clockwise by the amounts designated in FIG. 10 in order to achieve the desired orientation.

For the purpose of enabling Visual inspection of the wafer, the cover plates 83-83 do not extend into the station 82, and a microscope (not shown) is provided as an optical aid.

The wafers 20-20 advance into the station 82 until the leading one thereof engages a stop member 94 which centrally locates this wafer over an orientor, designated generally by the reference numeral 96, the next succeeding wafer moving into registration with a vertical bore 97 in the base 7 7 As will be described in more detail below, during the orienting of a wafer 20 by the orientor 96, a partial vacuum (hereinafter referred to as the hold vacuum) is drawn through the bore 97 to preclude movement of the wafer located thereover.

The orientor 96, as best seen in FIG. 9, comprises a hollow tubular member 99 secured to the top of a vertically movable and horizontally rotatable shaft 101. A vertical cylindrical housing 102 for the shaft 101 is Secured to the underside of the track 22 by suitable means and carries an electromagnetic coil 103 adjacent to its lower extremity, a pair of sleeve bearings 104 -104 being disposed intermediate the shaft 101 and the housing 102 to enable free movement of the shaft. When energizing current is supplied to the coil 103 it coacts with an armature 106, Secured to the underside of the shaft 101, to provide vertical upward movement of the orientor 96, the amount of movement being limited by the engagement of a flange 107 formed at the top of the shaft with a thrust washer 108 secured to the underside of the track 22. Upon vertical movement of the shaft 101, the tubular member 99 moves through a vertical passageway 110 to engage, seat and carry a wafer 20 in registration therewith upwardly. When the shaft 101 is in its uppermost vertlcal position, the wafer is in horizontal alignment with a tube 109, which projects horizontally from a block 111 seated on the land 79. The tube 109 is arranged for connection with a source of pressurized nitrogen (not shown). If it has been determined that the wafer is defective, a Stream of nitrogen is introduced into the tube 109 to blow the wafer off the orientor tube 99 and into a funnel-shaped receptacle 112 located adjacent to the track 22. From the receptacle 112 the wafer is drawn by a partial vacuum to a reject container (not shown).

If the wafer is acceptable, it is secured to the free end of the orientor tube 99 during the vertical movement of the orientor 96 by means of a partial vacuum. This is accomplished by providing an Opening 113 in the tube 99 adjacent to its lower end, and introducing a partial vacuum through a horizontal bore 114 to a gas tight vertical Chamber 116 formed in the track 22. It should be noted that by virtue of this arrangement, a vacuum is maintained within the orientor tube 99 during both its rotational and vertical movement. In order to faclitate the downward movement of the shaft 101 upon de-energization of the coil 103, a compression spring 117 is disposed in the Chamber 116 with its upper end contacting the ceiling of the Chamber and its lower end contacting an annular blank 118 Secured to the tube 99.

Rotational motion is imparted to the shaft 101 by a motor 119 (FIG. 13) whose shaft 124 drives a flexible shaft 121 connected to the shaft 101. A cam 122 having four detent receiving means, such as lobes 123-123 equally spaced around the periphery thereof is secured to the motor shaft 124 to enable 90o incremental rotation thereof and, hence, of the shaft 101 as well. The incremental rotation is accomplished by energizing for one of three predetermined time intervals a conventional relay 126 having its armature 125 modified to include a detent 127 which, as seen, is normally engaged With the leading edge of one of the lobes 123. Upon energization of the relay 126, the armature 125 retracts, thereby retracting the detent 127 to free the motor for rotation, the motor continuing to rotate until after de-energization of the relay the detent re-engages the leading edge of a cam lobe 123. It should be noted that during each 90 rotation of the cam 122, the relay armature 125 is held in the retracted position by virtue of the engagement of the detent 127 with the perpheral surface of the cam intermediate a pair of lobes 123--123.

The three ti-me intervals correspond to the time necessary for the motor to rotate through angles of 90, 180 and 270 respectively. Thus, for example, if the speed of the motor is 60 r.p.m. as in the present instance, the motor -will rotate through 90 in .25 second, through l80 in .5 second and through 270 in .75 second. The three time intervals are selected accordingly, with each being slightly less than the actual time necessary to complete its oorresponding rotation, as Will be seen below.

The time intervals are provided by a circuit, designated generally by the numeral 1218, which forms a part of FIG. 13. The circuit includes three like transistor

time delay circuits

129, 131 and 132, the respective outputs of which are connected to the base 133 of an output transistor 134 having a relay 136 connected in its collector circuit.

Biasing resistors

137 and 138 are connected to the emitter 139 and to a D.C. power supply 141. The base 133 of the transistor 134 is additionally connected through a resistor 142 to the positive terminal of the supply 141.

Since the operation and Structure of each time delay circuit is essentially identical only one, i.e., 129, will be described in detail. The circuit 129 includes 4a transistor 143 having it-s emitter 144 connected to the negative terminal of the supply 141 and its collector 146 connected to the base 133 of the o-utput transistor 134 and to the resistor 142. The base 147 of the transistor 143 is connected through a high value -variable resistor 148 to one end of a relatively lower value fixed resistor 149 -and to one end of a capacitor 151, the other end of the resistor 149 being Iconnected through a normally open switch contact 153 to the positive terminal of the supply 141 and the other end of the capacitor 151 being connected to the negative terminal of the supply. The switch contact 153 is controlled by a four position lever switch 152. The four positions of the switch correspond to the amount of rotation necessary to rotate the wafer to the desired orientation, .e., 90, 180 and 270 respectively. In the position of lthe switch -corresponding to 90, the switch contact 153 would be closed; in the position of the switch corresponding to 180, the switch contact 154 would be closed; land in the position of the switch corresponding to 270, the switch contact 156 would be closed. The operation and function of other contacts of the switch 152 will be further described below.

In ope-ration, if none of the

contacts

153, 154 or 156 are closed, :a signal is applied from the supply 141 through the resistor 142 to the base 133 of the output transistor 134 of a suflicient magnitude to turn it ON and thereby energize the relay 136. However, when one of the contacts is closed e.g., contact 153 of the 90 time delay circuit 129, the capacitor 151 thereof is charged through the low value fixed resistor 149 resulting in the transistor 143 being turned ON and its collector voltage and, hence, the voltage at the base 133 of the out-put transistor 134 as well, dropping to a low value, i.e., a value lower than the emitter voltage of the transistor 134. This results in a turning OFF of the transistor 134 and a de-energization of the relay 136.4 Upon a subsequentopening of the contact 153, the charge on the capacitor 151 flows into the base 147 and keeps the transistor 143 ON for a time interval dependent upon the value of the capacitor 151 and the setting of the variable resistor 148. For example, in the present instance the values would be selected so that a time delay of .2 second results. After discharge of the capacitor 151 the transistor 143 turns OFF resulting in the output transistor 134 being turned ON and the relay 136 being de-energized. As will be described in more detail below, a normally closed contact 136a of the output relay 136 is in a circ-uit which along -with the switch 152 .controls the Operation. of the orientor control relay 126; hence, this latter relay is energized for the length of time the output relay 136 remains energized upon the closing and opening of the switch contact 153.

The Operation of the 180 and 270

time delay circuits

131 and 132 respectively is similar to that of the time delay circuit 129 with the exception that the values of their respective capacitors and the settings of their respective variable resistors are selected to provide time delays of .45 second and .7 second, respectively.

Refern'ng again to FIG. 8, the stop member 94 is generally L-shaped and is pivotally movable between an upper and lower portion. In the lower position the stop member 94 (as shown) functions to centrally locate a wafer 20 over the passageway communicating With orientor 96, and in its upper .position 4functions to allow a wafer 20 to move out of the station 82 after orientation thereof. The stop member 94 is Secured to one end of a rod 157 which is journaled for rotation about a horizontal axis in the support block 111. The other end of the rod is connected through suitable linkages158 and 159 to an armature 161 of a relay 162 mounted on the track support 34. Energization of the relay 162 results in rotation of the rod 157 to rotate the stop member 94 counterclockwise (FIG. '8) to its upper position, and deenergization of the relay causes the stop member to rotate clockwise to its lower position in engagement with the channel base 77.

Since the fixed cover plates 83 -83 `do not extend into the station 812, during the transfer of a. Wafer from the bore 97 into engagement with the stop member 9'4 a mov-able cover plate 163 is actuated to cover the channel 76 and the-reby preclude a climbing of the wafers.'

The movable cover plate 163 is generally L-shaped and has one end Ifixed to the upper end of a vertical shvaft 164 journaled in track land 79' for rotati-on about its vertical axs. The bottom of the shaft 164 is connected through

suitable linkage

166 and 167 to a plunger 168 of a :solenoid 169 mounted on the track support 34. Energization of the -solenoid 169 lresults in rotational movement of the shaft 164 to cause the cover plate 163 to move to a retracted position las shown in FIG. 8, there'by uncovering the channel 76 and allowing unobstructed viewing of the wafer; conversely, de-energization of the solenoid 169 -results in t-he cover plate 167 covering the channel 76.

After orientation, to -be described later in more detali, the oriented w-afers 20-20 are fed to a removable, channeled mag'azine 171 (FIG. 1). The channel 172 of the magazine 171 is accurately aligned with the exit end of the track channel 76 by a -pllurality of suitable positoning and securing means 173, 174, 175 and 176.

To determine when the magazine 171 is full and to deactuate the respective vibratory drives of the circular feeder 21 and linear track 22 accordingly, at the entrance of the magazine 171, light from a source 177 is radiated -o-n a photocell 178 (FIG. 2) through suitable ape-rtu-

res

170 and 180 in the 4base 77 .and magazine, respectively. The photocell 178 is connected in the circuit of FIG. 11 which fuctions in a like =manner to the circuit of FIG. 7 previously described. Thus, when the light to the photocell 17 8 is bloc-ked for a predetermined time interval, which will occur when the mag-azine 171 is full, an input signal of suflicient magnitude is applied to an amplifier 179 to energize =a relay 181 in the output thereof, hereinafter referred to as the full magazine relay. A normally open contact 18111 (FIG. 12) of the relay 181, as will be seen shortly, is con-nected to the respective vibrato-ry drive circuits of both the circular feeder and linear track, and is functional upon energization of the relay 181 to deactuate bot-h drives.

It should be obvious, that instead of being fed to a magazine, the waters after orientation can be fed directly to a subsequent processing :station or machine.

Operation Refe-r-ring now to FIGS. 12 and 13 combined, as shown in FIG. 14 there is ill-ustrated a control circuit for the apparatus. In order to facilitate association of relays and relay contacts, relay contacts operated by a relay are designated by the relay reference num-ber followed by an identifying subscript letter. For example, the two relay contacts controlled by a relay 191 are designated 19111 vand 191b. Switch contacts are readily distinguishable from relay contacts since each switch contact is designated by a whole number only.

Preparatory to operation, a [main power switch 182 is closed to energize a pair of

bus lines

183 and 184 from a suitable source of A.C. power 185, in the instant case, 115 v., 60 cycles. This results in a relay 186 being energized through va normally closed feed button contact 187 an-d a normally closed contact 18811 of a relay 188.

A start button contact 189 is then momentarily dep-ressed, thereby energizing a start relay 191 through a normally closed stop button contact 190. Energization of the start relay 191 closes its normally open -co-ntacts 19111 and 191b. Since the full magazine relay 181 (FIG. 11) is normally energized, its normally open contact 18111 is closed at this time; hence, upon closure of contact 19111, a holding circuit is established for the start relay 191. Closure of contact 191b conditions respective energizing circuits for the linear vibratory drive coil 36 and the drive control solenoid 192 of the circular feeder 21, the

contact

186,11 being ,open at this time by virtue of the previous energization of the relay 186, end the contact 9211 being closed -at this time since the accumulation control |relay 92 (FIG. 7) is normally energized. Both the linear vitbratory drive coil 36 and the drive control solenoid 192 are energizab-le through respective auto-

transformers

193 and 194 and

respective rectifier diodes

196 and 197, w-hose function is to provide D.C, Operation of each drive unit.

To commence Operation, the feed button contact 187 is depressed to de-energize the relay 186, which close the contact 18611 and thereby completes the respective energizing circuits for the linear vibratory drive coil 36 -and the circular feeder drive control solenoid 192. Accordingly, wafe-rs are fed from the circular feeder 21 to the linear track 22; formed into a single row; screened to eliminate oversize :and undersize wafers, as well as particles; surface tested t-o remove those wafers from the track which are advanced with their top surface contacting the sidewall 38; and advanced along the horizontal channel 76. The operator maintains the feed button 187 depressed until the leading wafer is fed against the stop member 94, which is in its lower position since no energizing current is supplied to its operating relay 162 at this time. The feed button 187 is then released, resulting in the following actions: energization of the solenoid 169 to retract the movablle cover plate 163 (FIG. 8) -and thereby uncover the channel 76 to rallow unobstructed inspection of the leading wafer; energization of a solenoid 193 of a solenoid operated valve (not shown) to actuate the hold vacuum, whereby the wafer in registration with bore 97 is restrained; energization through a no-rmally closed contact 16211 of the stop relay 162 of ra solenoid 194 of a solenoid operated valve (not shown), to draw a partial vacuum through the orientor tube 99 and thereby secure the leading w-afer thereon; and re-energization of the relay 186 to de-e-nergize the drive coil 36 and solenoid 192 of the linear track 22 land circular feeder 21 respectively. The present condition of the apparatus will hereinafter be referred to as its inspection condition, that is, the apparatus is now in a condition to enable inspection of a wafer.

Next, an operator views the leading wafer 20 through a microscope (not shown) to determine Whether the wafer is acceptable and, if acceptable, the orientation thereof. If the wafer is unacceptable, the operator operates a reject switch 196 to close its normally

open contacts

197 and 200. Closure of the

contacts

197 and 200 energizes a solenoid 198 of a solenoid operated valve (not shown) to introduce a nitrogen stream through the reject tube 109 (FIG. 9) and completes a circuit to a relay 199 which closes its contacts 19911 and 199b.

Closure of contact 19911 energizes the relay 188, thereby etfecting a closure of the contacts 18811 and 188c and `an Opening of contact 18811, the closure of contact 18817 completing a holding circuit for the relay 188 through the closed feed `button contact 187, .and the opening of contact 18811 de-energizing relay 186 to re-energize the drive coil 36 and solenoid 192 of the circular feeder 21 and linear track 22, respectively. The closure of contact 188c energizes the stop control relay 162 to raise the stop member 94 to its upper position, close the contact 162b and open the contact 16211. The Opening of contact 16211 deactuates the vacuum to the orienter tube 99, and the closure of contact 16211 completes a circuit to the orienter lift coil 103 through the contact 197, the contact 200 and a rectifier 201, the resistor 202 and capacitor 203 associated with the rectifier forming a filter for the -rectified signal applied to the coil 103. As a result of the energization of the lift coil 103, the shaft 101 raises, whereupon the wafer is contacted by the actuated nitrogen stream and is blown off the orientor tube 99 to the receptacle 112 and, thence, to a reject container (not shown). Upon release of the reject switch 196, the relay 199 is de-energized and the circuit :to the lift coil 103 is opened, resulting in a lowering of the shaft 101. The present condition of the apparatus, which Will hereinafter be referred to as the rest condition, is as follows: both drive circuits are actuated; the movable cover plate 163 is retracted; the hold vacuum is actuated; and the stop 94 is in its upper position by virtue of relay 188 and, hence, relay 162 remaining energized.

To feed another wafer into the station, the feed button contact 187 is depressed, resulting in deactuation of the hold vacuum, movement of the movable cover plate 163 to cover the channel 76, de-energization of relay 188, and movement of the stop member 94 to its lowered position. The feed lbutton contact 187 is maintained depressed -until the wafer which had been held by the hold vacuum is fed into engagement with the lowered stop member 94. The feed button contact 187 is then released, thereby placing the apparatus in its inspection condition.

If the wafer under inspection is acceptable, the four position switch 152 is operated selectively to a position thereof which corresponds to the amount of rotation necessary to rotate the wafer to the desi-red orientation. Obviously, if the wafer is of the desired orientation, no rotation is required and the switch is operated to its 0 position, resulting in the closure of contact 204 and the Opening of contact 206. The closure of contact 204 energizes relay 199, whereupon the same action which took place when this relay Was energized in the reject situation above ensues, With the exception that the reject nitrogen Stream is not actuated and the vacuum to the orientor tube 99 is continuously actuated. Accordingly, the stop member 94 moves to its Upper position and the shaft 101 raises, the wafer remaining on the orientor tube 99. The continuous actuation of the orientor tube vacuum is achieved by virtue of a circuit being completed to the solenoid 194 through the closed 0 contact 204, the reject switch armature 196, the reject switch contact 207 and the closed contact 1991). Upon release of switch 152 to i 13 its inoperative position, the lift coil 103 is de-energized to lower the shaft 101 and the apparatus is placed in its rest condition, with the wafer under consideration being advanced to the magazine 171.

If the wafer under inspection is of an undesirable orient-ation, the switch 152 is operated either to its 90, 180 or 270 position and, accordingly, opens either contact 208, 209 or 211 and closes either

contact

153, 154 or 156, respectively. Opening of either

contact

208, 209 o-r 211 disables the rotary control relay 126, While closure of either

contact

153, 154 or 156 selects one of the three

time delay circuits

129, 131 or 132 to de-energize relay 136, as was explained above. De-energization of relay 136 closes contact 136a which, in turn, results in energization o-f relay 199 through the contact 13611, the normally closed contact 126a of the rotary control relay 126, the reject switch armature 196 and the reject switch contact l207. Accord-ingly, the same action which ensued upon the energization of relay 199 in the orientation eXample above, takes place, that is: the shaft 101 is raised; the vacuum to the orientor tube 99 is maintained actuated; and the stop member 94 is moved to its upper position. Upon release of switch 152 to its inoperative position, a circuit is completed to the rotary control relay 126, the contact 136a, as explained above, remaining closed for a time interval-dependent upon which time delay circuit was selected. Energization of relay 126 closes

contact

126b and 126c and opens contact 12611. Closure of contact 126b maintains the energization of those circuits which were lpreviously energized through contact 126a, rand closure of contact 126c energizes the motor 119 which is f-ree to rotate since the cam 122 is disengaged upon the energization of relay 126. Accordingly, rotary motion is imparted to the sha-ft 101. Upon expiration of the selected time delay circuit Itime interval, the relay 136 reenergizes thereby opening the contact 13611 and de-energizing the.rotary control relay 126; however, due to the engagement of the relay detent 127 with the ca-m peripheral surface intermediate a pair of lobes 123, the

contacts

126b and ,126c remain closed.. The shaft 101 continues to rotate for a short time until the detent 127 engages a cam lobe 123 thereby arresting the motion of the motor 124 and Opening the

contacts

126b and 126c. Opening of contact 1266` d'e-ener'gizes the motor 119, while Opening of contact 126b de-energizes -the lift coil 103 causing the shaft to lower, and places the apparatus in its rest conditon, the oriented wafer Ibeing advanced to the magazine 171.

It is to be understood that the above-described arrangei ments are simply illustratve of the application of the principles of the invention. Numerous other arrangements may be `devised by those skilled in the art which will embody the principles of the -invention and fall within the spirit and scope thereof.

What is claimed is: 1. An orienting device for rotating an article to a desired angular direction, which comprises:

rotatable means movable between a first and a second position, in said first position said rotatable means being out of engagement With an article to be rotated and in said second position said rotatable means being in engagement with and holding said article; means for moving said rotatable means between said first .and second positions; means for imparting rotary motion to said rotatable means; and control means for controlling the rotation of said rotary imparting means in accordance with a desired angular direction of said article, said control means including a plurality of selectively actuable time delay circuits, the time delay of each circuit corresponding to the time required for the rotary imparting means to rotate through a particul-ar angle. 2'. An orienting device for rotating an -article to a desired angular orientation which comprises:

a linearly movable and horizontally rotatable shaft having a tubular element connected thereto, the free end of the tubular element being adapted to hold an article;

an electromagnetic coil cooperatively -associated with the shaft for imparting linear movement thereto upon energization thereof to cause said tubular member to engage and hold an -article to be rotated;

means connected to said shaft for imparting rotary movement thereto;

means engageable With said rotary imparting means for controlling the motion thereof;

a plurality of selectively actuable time delay circuits, the time delay of each circuit corresponding to the time required for the rotary imparting means to rotate through aparticular angle;

means responsive to the actuation of -any one of the time delay circuits for Operating the controlling means 4for a time interval dependent upon the selected time delay circuit; and

means for selecting one of said plurality of time delay circuits in accordance with a desired angular orientation of said. article.

3. An orienting device in accordance with cla-im 1 further including:

means for drawing a partial vacuum through the tubular element to hold an article thereon during linear and rotary movement of the shaft.

4. An orienting device for rotating an article to a desired angular orientation which comprises:

,an electromagnetic coil wound around said shaft for imparting linear movement thereto upon energization thereof to cause said tubular member to engage and hold an article to be rotated;

-a motor connected to the sha-ft for rotating the same;

a cam connected fiXedly to the motor and having a plurality of equally spaced detent receiving means disposed around its periphery; and

electromagnetic means having a detent, said electromagnetic means detent being normally engaged with one of said cam detent receiving means to preclude rotation of said shaft and being operable upon energization of said electromagnetic means for a time interval related to the speed of the motor to |disengage said one cam detent receiving means and permit rotation of said shaft, said shaft continuing to rot-ate until, after the expiration of said time interval, said detent engages another one of said detent receiving means.

5. A control system -for a rotary drive comprising:

means engageable with the rotary drive to preclude rotation thereof and selectively operable for `disengaging said rotary drive to allow rotation thereof;

-a plurality of selectively actuable time delay circuits, the time delay of each circuit corresponding to the time required for the rotary drive to rotate -through a particular angle; and

means responsive to the actuation of any one of the time delay circuits for Operating the selectively operable means for -a time interval dependent upon the selected time delay circuit, said latter mentioned means thereby alternately disengaging and engaging said rotary drive to allow rotation thereof for a time interval substantially equal to said selected time interval.

6. Rotary drive apparatus Icomprising:

rotary drive means;

a plurality of equally spaced detent receiving means connected to the rotary drive means;

a detent, said detent being engageable with a detent receiving means to preclude rotation of said rotary drive and being selectively operable for disengaging a detent receiving means to allow rotation Of said rotary drive;

a plurality of selectively actuable time delay circuits, the time delay Of each circuit corresponding to the time required for the rotary drive to rotate through a particular angle; and

means responsive to the actuation of any one of the time delay circuits for Operating the detent for a time interval dependent upon the selected time delay circuit to thereby cause said detent to alternately disengage and engage a detent receiving means to allow rotation of said rotary drive through an angle corresponding to said selected time interval.

7. Rotary drive apparatus comprising:

a motor;

a plurality of equally spaced detent reoeiving means connected to the motor;

a first relay having a detent, said detent being engageable with a detent receivin-g means for precluding rotation of the motor and being selectively operable for disengaging a detent receiving means to allow rotation of said motor;

a plurality of selectively actuatable time delay circuits, the time delay of each circuit corresponding to the time required for the motor to rotate through a particular angle; and

a second relay responsive to the actuation of any one of the time delay circuits for Operating the first relay to cause said detent to alternately disengage and engage a detent receiving means to allow rotation of said motor through an angle corresponding to said selected time interval.

8. Rotary drive apparatus comprising:

a motor;

a plurality of equally spaced detent receiving means connected to the motor;

a first relay having a detent, said detent being engageable with a detent receiving means for precluding rotation of the motor and being selectively operable for disengaging a detent receiving means to allow rotation of said motor;

a plurality of selectively factuable time delay circuits, one less than the number of detent receiving means, the time delay of each circuit corresponding to the time required for the motor to r-Otate through a particular angle; and

a second relay responsive to the actuation of any one of the time delay circuits for Operating the first relay to cause said detent to alternately disengage and engage a detent receiving means to all-Ow rotation of said motor through an angle corresponding to said selected time interval.

9. Rotary drive apparatus comprising:

a motor;

a plurality of equally spaced detent receiving means connected to the motor;

a plurality of time delay circuits, one less than the number of detent receiving means, the time delay of each circuit corresponding t-o the time required for the motor to rotate through a particular angle;

means for selectively actuatng one of the time delay cir-cuits in aocordance with a desired motor angular rotation; and

a second relay responsive to the actuation of any one of the time delay circuits for -operating the first relay to cause said detent to alternately disengage and engage a detent receiving means to allow rotation of said motor through an angle corresponding to said selected time interval.

10. Apparatus in accordance with claim 9 wherein said selectively actuating means comprises:

a switch having a plurality of individually closeable normally open contacts for each time delay circuit, each of said normally open contacts being connected in a distinct time delay circuit for Operating the same upon its closure, the switch having a plurality of corresponding normally closed contacts synchronously operable with said normally open contacts and each being connected to the first relay for energizing the same after a closing and Opening of one of said normally open contacts to energize the second relay, the first relay remaining energized for a time interval determined by the selected time delay circuit.

11. Apparatus in accordance with claim 10 wherein each time delay circuit com-prises:

References Cited by the Examiner UNITED STATES PATENTS 2,702,609 2/1955 Frazier 192-142 X EVON C. BLUNK, Primary Examiner.

E. A. SROKA, Assistant Examiner.

Claims

1. AN ORIENTING DEVICE FOR ROTATING AN ARTICLE TO A DESIRED ANGULAR DIRECTION, WHICH COMPRISES: ROTATABLE MEANS MOVABLE BETWEEN A FIRST AND A SECOND POSITION, IN SAID FIRST POSITION SAID ROTATABLE MEANS BEING OUT OF ENGAGEMENT WITH AN ARTICLE TO BE ROTATED AND IN SAID SECOND POSITION SAID ROTATABLE MEANS BEING IN ENGAGEMENT WITH AND HOLDING SAID ARTICLE; MEANS FOR MOVING SAID ROTATABLE MEANS BETWEEN SAID FIRST AND SECOND POSITIONS; MEANS FOR IMPARTING ROTARY MOTION TO SAID ROTATABLE MEANS; AND CONTROL MEANS FOR CONTROLLING THE ROTATION OF SAID ROTARY IMPARTING MEANS IN ACCORDANCE WITH A DESIRED ANGULAR DIRECTION OF SAID ARTICLE, SAID CONTROL MEANS INCLUDING A PLURALITY OF SELECTIVELY ACTUABLE TIME DELAY CIRCUITS, THE TIME DELAY OF EACH CIRCUIT CORRESPONDING TO THE TIME REQUIRED FOR THE ROTARY IMPARTING MEANS TO ROTATE THROUGH A PARTICULAR ANGLE.