US3460468A

US3460468A - Electrical printing methods and apparatus for decorating cylindrical articles

Info

Publication number: US3460468A
Application number: US434819A
Authority: US
Inventors: William E Johnson
Original assignee: Owens Illinois Inc
Current assignee: OI Glass Inc
Priority date: 1965-02-24
Filing date: 1965-02-24
Publication date: 1969-08-12
Anticipated expiration: 1986-08-12

Description

12 .1959 w. E. JOHNSON 3,460, 68

ELECTRICAL PRINTING METHODS AND APPARATUS FOR nnconwme CYLINDRICAL ARTICLES Filed Feb. 24. 1965 3 Sheets-Sheet 1 -u m M E18 INVEN QR Mu/nqiJ/rgjod Aug. 12, 1969 FOR DECORATING CYLINDRICAL ARTICLES Filed Feb. 24. 1965 w. E. JOHNSON 3,460,468 ELECTRICAL PRINTING METHODS AND APPARATUS I5 Sheets-Sheet 2 I no I [172] 1 72w II! II III I II Aug. 12,

ELECTRICAL PRINTING METHODS AND APPARATUS w. E. JOHNSON FOR DECORATING CYLINDRICAL ARTICLES Filed Feb. 24 1965 Cd r11 5 Sheets-Sheet 5 p 2 45 I [I] 2 31R flrroRNEKS United States Patent 3,460,468 ELECTRICAL PRINTING METHODS AND AP- PARATUS FOR DECORATING CYLINDRI- CAL ARTICLES William E. Johnson, Temperance, Mich., assignor to Owens-Illinois, Inc., a corporation of Ohio Filed Feb. 24, 1965, Ser. No. 434,819

Int. Cl. B41f 17/22; B411 13/02; G03g 15/00 US. Cl. 10140 11 Claims ABSTRACT OF THE DISCLOSURE Electrical printing methods and apparatus for decorating cylindrical articles such as bottles, tumblers and the like. Printing powder particles are electrically transferred directly from a fiat surfaced source such as a powder bed through a flat stencil screen to the curved article surface. Relative motion between the article, bed and stencil is established so that the article is rolled laterally across the image area of the stencil at a umform distance from the stencil to scan the image. Powder particles being transferred from the bed to the article surface are confined by a slotted plate to a relatlvely narrow band encompassing a plane normal to the bed surface and passing through the axis of relative rotation of the article.

In my prior application Ser. No. 393,817, filed Aug. 31, 1964, now abandoned, refiled as a continuation-in-part, and issued as Patent No. 3,402,659, there is disclosed certain methods and apparatus for electrically transferring printing powder particles from a powder supply through a stencil screen to the surface of a flat article. As disclosed in Patent No. 3,402,659 the powder s disposed in a loosely packed layer beneath a stencil screen formed with an image shaped aperture, and the article to be printed is brought into vertical registry above the screen. Electric potential pulses are applied to electrically charge the powder particles in the supply and to establish an electric field oriented to electrically attract particles from the supply through the image aperture of the screen to the article surface. In this arrangement, the entire image is transferred at one time and, because of the parallel uniformly spaced relationships between the article surface, stencil screen and powder bed surface, an image of uniform density is applied to the flat article.

In many instances, it is desirable to decorate art1c-les which are not fiat, one common example being repreented by glass bottles or tumblers in which the surface to be decorated is of a generally cylindrical shape. Typically, as in the case of printing a label directly upon the surface of a glass bottle, such decorating operations involve the decorating of large quantities of articles on a mass production basis. Where the article being decorated is a glass article, it is desirable that the article be electrically conductive. This may be accomplished by applying an electrically conductive coating to the article, but in the usual case the article is heated to a relatively high temperature during the decorating operation. From a practical standpoint it is advantageous to apply the decoration to the glass bottle while the bottle is still residually heated from the bottle forming operation. Thus, for its most practical application, an electrical printing process for decorating hot glass bottles should be capable of a production rate which can be matched to the relatively high output of a glass bottle forming machine.

Presently available processes for electrically applying printing powder images to curved article surfaces on a production line scale are almost entirely restricted to various types of offset decorating processes. In a 3,460,468 Patented Aug. 12, 1969 er: I

typical offset process, the printing powder image is electrically transferred from a powder supply bed through a stencil screen to a flat offset plate to form an image shaped layer of powder particles on the surface of the plate. The image is then transferred from the plate to the article surf-ace by rolling the article surface laterally across the image on the plate. While offset processes can be performed at high production rates, it isnecessary to provide complex mechanism for conditioning or manipulating the plates into and out of relationship with the powder supply and with the article being decorated.

While various processes for applying a powder image directly to a cylindrical or conical article surface from a powder supply bed through a stencil screen have been developed, in the usual case these direct printing processes require preparation or reconditioning of the powder bed in Ways such that these processes are not well adapted to high production rates.

Accordingly, it is an object of the present invention to provide methods and apparatus for decorating curved article surfaces by electrically transferring printing powder particles directly from a source through a stencil screen to the articles at a high rate of production.

It is another object of the present invention to provide methods and apparatus for applying image-shaped layers of printing powder particles directly to curved article surfaces which do not require preparation or reconditioning of the powder bed in a manner which limits the production rate.

It is another obiect of the present invention to provide methods and apparatus for transferring printing powder particles from a flat powder bed through a stencil screen directly to a curved article surface which results in a clear and sharply defined image on the article.

The foregoing and other objects are achieved by depositing a bed of printing powder particles in a layer of uniform thickness upon a fiat supporting surface such as a conveyor belt or reciprocating plate. A semi or nonconductive plate is located in a horizontal position immediately above the powder bed. The plate is formed with an elongate, relatively narrow slit which extends entirely across the width of the powder bed. A fiat stencil screen having an image defining aperture is located immediately above the plate and the article being decorated is brought into a decorating position in spaced relationship above the screen with the axis of the curved surface of the article disposed in a horizontal position in parallel vertical registry with the slit in the plate. The article is supported for rotation about its axis. In the case of articles of noncircular cross section, for example a bottle of elliptical cross section, the axis of rotation may be supported for cyclic movement to compensate for the surface configuration.

During the decorating operation, an electric field is established which electrically charges powder particles in the bed and is oriented to attract the charged particles upwardly through the slit in the plate and the image aperture of the screen to the article surface. The screen and slitted plate are supported for horizontal movement relative to each other in a direction perpendicular to the longitudinal extent of the slit. At the beginning of the decorating operation, the slit is located at one edge of the image aperture, and during the decorating operation the screen and plate are moved relative to each other so that the slit is traversed entirely across the image aperture in a scanning type relationship. During relative movement between the screen and slitted plate, the powder bed and screen are maintained against horizontal movement relative to each other and the bottle axis is maintained in vertical registry with the slit in the plate. During the hor- 3 izontal relative movement between the screen and the plate, the bottle is rotated, as by contacting its surface with a rail ion the screen so that the bottle rolls with its periphery moving at the same velocity as the horizontal movement of the screen relative to the bottle axis.

The electric field is established by connecting the bottle sunfiace to an electric potential source and by connecting a second electric potential source of opposite polarity to an electrically conductive member located beneath the powder bed. In all cases, the electric field is such that only powder particles in the bed in or close to vertical registry with the slit are electrically charged. In one case, this may be accomplished by forming the electrically conductive member as an elongate relatively narrow member located in vertical registry with the slit in the plate. In this case, the conductive member is maintained in registry with the slit throughout the decorating operation. Alternatively, an electrically conductive plate of dimension such as to entirely underlie the slitted plate may be employed. In this case, the slitted plate is of a material having substantially the same electrical resistivity characteristics as the powder of the bed. The slitted plate is placed in contact with the upper surface of the powder bed, and those particles not in registry with the slit do not become charged, but instead act as merely a series resistance between the conductive plate and the slitted plate.

Other objects and features of the invention will become apparent by reference to the specification and to the drawings.

In the drawings:

FIGURE 1 is a schematic side elevational view, partially in cross section of one embodiment of the invention;

FIGURE 2 is a schematic side elevational view, partially in cross section of a second embodiment of the invention;

FIGURE 3 is a schematic side elevational view, partially in section of a third embodiment of the invention;

FIGURE 4 is a detailed cross sectional view taken upon line 4-4 of FIGURE 3',

FIGURE 5 is a schematic side elevational view, partially in cross section, of still another embodiment of the invention.

FIGURE 6 is a schematic diagram of an electric control circuit;

FIGURE 7 is a schematic diagram of a pneumatic motor control circuit;

FIGURE 8 is a schematic diagram of a second form of electric control circuit; and

FIGURE 9 is a schematic diagram of a third form of electric control circuit.

In FIGURE 1, there is disclosed schematically one form of the invention in which an endless conveyor belt 10 of relatively thin rubber, neoprene, or a semi-conductive material which is operatively trained around a pair of end rolls 12 and 14 rotatably supported by conventional frame structure (not shown). The electrical conductivity characteristics of the belt should be in the same range of conductivity as that of the powder. End roll 12 is driven by conventional drive means M1 so that the upper run 16 of belt 10 moves from left to right as viewed in FIGURE 1.

A supply of printing powder particles 18 is dispensed onto upper run 16 of the belt near its upstream end from a schematically illustrated supply hopper 20, the rate at which powder is dispensed from hopper 20 being controlled in accordance with the rate of movement of the belt by conventional means, not shown. At spaced locations along upper run 16, a pair of

stationary frame members

22 and 24 extend transversely across and above upper run 16. The left hand frame member 22 as viewed in FIGURE 1 functions as a doctor blade to smooth and level the surface of powder particles 18 on upper run 16 to form a bed or layer of uniform thickness upon the belt as the particles are carried downstream beyond frame member 22.

Frame members

22 and 24 serve to support a fiat horizontally disposed plate 26 of an electrically non-conductive material in spaced relationship above the surface of the powder bed upon run 16 of the belt. A stencil screen 28 is mounted within a rectangular frame designated generally 30 which is supported upon the upper surface of plate 26 for horizontal movement in the direction indicated by the arrow A of FIGURE 1.

Preferably, stencil screen 28 takes the form of a relatively fine wire mesh which is coated in a fashion such that the coating fills the openings in the mesh. The coating material is chosen so that it can be removed from selected areas of the screen by a photographic process to thereby form an image defining aperture through the screen. Suitable materials and processes for preparation of a screen of this type are disclosed in United States Patent No. 3,100,150. The image aperture is schematically illustrated at 32. Screen 28 may be shifted horizontally in either direction parallel to the direction of movement of belt 10 by suitable means such as a pneumatic motor 34 having its piston rod 36 coupled to screen frame 30.

In the apparatus from FIGURE 1, the article being decorated may take the form of a cylindrical bottle B supported from suitable conveying means designated generally 38 as by a support yoke 40 which supports the bottle for free rotation about the axis of its cylindrical surface. This axis R is horizontally disposed during the decorating operation and extends in a direction perpendicular to the direction of movement of belt 10.

Conveyor 38 is driven, as by drive means M2, to convey bottles B which are to be printed into the position shown in FIGURE 1. When the bottle is in the decorating position shown in FIGURE 1, the axis R about which the bottle is supported for rotation is disposed in parallel vertical registry with a relatively narrow elongate s-lit 42 cut through plate 26. A limit switch LS1 is located to be engaged by support yoke 40 when the bottle is in the decorating position. Slit 42 is likewise in parallel vertical registry with a relatively narrow elongate electrically conductive member 44 which extends transversely beneath upper run 16 of belt 10. In FIGURE 1, slit 42 and conductive member 44 are shown in transverse cross section, the longitudinal extent of the slit and conductive member extending in a direction perpendicular to the paper. The longitudinal extent of slit 42 and conductive member 44 is greater than the corresponding maximum dimension of the image defining aperture 32 of stencil screen 28.

Conductive member 44 is electrically connected to one terminal of a high voltage source V1 while bottle B is electrically connected, as via a brush assembly schematically illustrated at 46 to one terminal of a second high voltage power supply V2. The opposite terminals of voltage sources V1 and V2, as well as screen 28, are connected to an electrical ground. For further details of the characteristics of voltage sources V1 and V2 and their operation, reference may be had to Patent No. 3,402,659.

In addition to the structure set forth above, a pair of limit switches LS2 and LS3 are mounted to be engaged by screen frame 30 when the screen frame is at its respective right or left-hand limits of travel as viewed in FIG- URE 1.

An exemplary control arrangement for the FIGURE 1 embodiment is disclosed in FIGURES 6 and 7. As indicated in FIGURE 7, a conventional pneumatic circuit employing a solenoid actuated 'four way reversing valve is used to control pneumatic motor 34. The circuit includes a pressure source P connected through the four-way reversing valve V to motor 34 via a rod-end conduit 48 and a head-end conduit 50. The valve control solenoids are designated 34E and MR, the connections in the valve being set up so that piston rod 36 is retracted when control solenoid 34R is energized, as indicated in FIGURE 7, the connections being reversed to extend the piston rod when solenoid 34E is energized.

The electrical control circuit is shown in FIGURE 6, and its operation may be best described in terms of operation of the apparatus of FIGURE 1. As an initial condition, it will he assumed that conveyor is stationary with a supply of powder supported upon upper run 16 of the belt, that screen frame 30 is at its extreme left-hand limit of movement at which the striker of limit switch LS3 is engaged, and that bottle conveyor 38 is moving to the left to advance a bottle B into the decorating position. Until the striker of limit switch LS1 is engaged by the arrival of the bottle at the decorating position, contacts LSla of limit switch LS1 (FIGURE 6) will remain closed to complete a circuit across supply lines L1 and L2 to motor M2. When the bottle arrives at the decorating position, conveyor 38 engages limit switch LS1 and contacts LSla are opened to stop the bottle conveyor drive motor M2.

When the bottle arrives at the decorating position and engages the striker of limit switch LS1, it closes a set of normally open contacts LSlb of limit switch LS1 to complete a circuit across supply lines L1 and L2 through the now closed contacts LSlb and a set of normally closed control relay contacts Ca to simultaneously energize belt drive motor M1, electric potential sources V1 and V2 and pneumatic motor control relay 34R.

Ener-gization of solenoid 34R causes pneumatic motor 34 to retract its piston, thereby drawing screen 28 to the right as viewed in FIGURE 1. As the screen moves to the right, the periphery of bottle B is frictionally engaged by a portion 52 of screen frame 30 to cause the bottle to roll or rotate about its axis R with a no-sli-p rolling motion as the screen is drawn to the right by the retraction of piston rod 36.

Simultaneously with the movement of screen 28 to the right as viewed in FIGURE 1, belt conveyor drive motor M1 is energized and the upper run 16 of the belt also moves to the right, the speed of movement of the belt and screen being identical. Energization of potential sources V1 and V2 establish an electric field which extends upwardly from conductive member 44 to the surface of bottle B, the bottle surface and conductive member being at opposite electric potentials. Powder supported upon belt 10 immediately above conductive member 44 becomes electrically charged and the electric field impels the charged powder particles upwardly through slit 42 and image aperture 32 of screen 28 to the surface of bottle B. The translatory movement of the screen combined with the rolling movement of the bottle relative to the screen advance the bottle surface into vertical registry with slit 42 at the same peripheral speed as screen 28 is moved horizontally.

The above described action continues until the screen arrives at its extreme right-hand limit of travel, at which time the striker of limit switch LS2 is engaged to close its normally opened contacts LSZa. Closure of contacts LSZa completes a circuit through a control relay C via a set of normally closed contacts LS3a of limit switch LS3, these last contacts being closed because the screen is not at its left-hand limit of travel. When control relay C is energized it locks itself in by closing a set of contacts Cb and simultaneously closes a second set of normally open contacts Cc to energize valve control relay 34E to thereby cause pneumatic motor 34 to reverse and drive in a direction extending piston rod 36 to return the screen toward its left-hand limit of travel.

When control relay C is energized, it opens its normally closed contacts Ca, thereby simultaneously de-energizing powder conveyor drive motor M1, voltage sources V1 and V2 and pneumatic motor control relay 34R. A fourth set of control relay contacts Cd are closed to energize bottle conveyor drive motor M2 to convey the decorated bottle away from the decorating position. Contacts Cd are connected in series with a set of normally open contacts LSlc controlled by relay LS1. These latter contacts are closed when the bottle is in the decorating position and hence mot-or M2 is energized to drive the bottle away from the decorating position until the striker of limit switch LS1 is disengaged. At this. time, contacts LSlc open, but contacts LSla are now closed to keep motor M2 energized and the motor continues to drive until the next successive bottle arrives at the decorating position.

In FIGURE 2 there is disclosed a second embodiment of the invention in which a support table designated generally 60 is mounted for horizontal reciprocatory movement. Table 60 is driven in horizontal reciprocatory movement by mean of a rack 62 on the table which is meshed with one or more pinions 64, pinions 64 being driven by a suitable reversible drive motor M3. An electrically conductive plate 66 is mounted upon table 60 and surrounded by an upwardly projecting frame 68 of electrical insulating material which extends entirely around the side edges of plate 66 to define a recess within which a powder bed 70 is received. Powder is supplied to the bed by means of a hopper such as 72.

A flat plate 74 of electrically non-conductive material having an elongate slit 76 is supported in a stationary position overlying the powder bed. A stencil screen assembly designated generally 78 of construction identical to that of the FIGURE 1 embodiment is supported for horizontal movement across the top of plate 74 and is driven in movement in the same fashion as the FIGURE 1 embodiment by a pneumatic motor designated generally 80. A bottle B is conveyed to and from registry with slot 76 by a conveyor mechanism 38 identical to that employed in the FIGURE 1 embodiment.

As in the FIGURE 1 embodiment, voltage sources V1 and V2 are respectively connected to plate 66 and to bottle B.

The control system for the embodiment of FIGURE 2 can be precisely the same as that described in connection with the embodiment of FIGURE 1 above. It will be noted that movement of table 60 is simultaneous with that of the screen assembly 78 and hence the control of reversihle table drive motor M3 can be accomplished by the same circuitry employed to control the reversible pneumatic motor 80.

The embodiment of FIGURE 2 differs from that of FIGURE 1 in that instead of employing narrow elongate conductor 44 of the FIGURE 1 embodiment, plate 66 extends entirely across the bottom of the powder bed. Plate 74 is in direct contact with the top of the powder bed and only those particles which are in registry with slot 76 can move. By making plate 74 of a material having the same electrically resistive characteristics as those of the powder, only powder in the region of the slit becomes electrically charged; powder out of registry with the slit effectively acting as a series resistance between plate 66 and plate 74.

In FIGURES 3 and 4, still another embodiment of the invention is disclosed. In this embodiment, an endless conveyor belt of semi-conductive material is operatively tnained around a pair of end rolls 92 and 94, a suitable conveyor drive motor M4 being employed to drive end roll 92 to advance the belt. Powder is dispensed onto the upper run of the belt as from a hopper 96. A stationary plate 98 of electrically conductive material is mounted beneath the upper run of belt 90 in supporting relationship with the belt. Mounted upon plate 98 and extending along each side edge of the conveyor belt are a pair of upwardly projecting walls 100 of electrical insulating material which serves to slidably support a plate 102 of electrical insulating material.

Plate 102 is mounted for sliding movement transversely of the conveyor, as best seen in FIGURE 4, and is driven in transverse reciprocating movement by a pneumatic motor assembly designated generally 104. As in the pre vious cases, plate 102 is pnovided with an elongate slit 106, in this case the longitudinal extent of silt 106 i parallel to the direction of movement of conveyor 90. A stencil screen 108 is supported in a stationary position above plate 102 land a bottle conveyor designated generally 110 is employed to convey bottles B to and from operative registry with the apparatus. As in the case of the previous embodiments, the bottle B is supported for free rotation about its longitudinal axis by the conveyor 110. Conveyor 110 may be for all practical purposes identical to the conveyor 38 of the FIGURE 1 embodiment, although it is controlled in a manner to be described below in a slightly different fashion during the decorating cycle. A pad 112 is mounted upon the screen assembly to frictionally engage the bottle periphery to rotate the bottle about its axis as the bottle is carried transversely across stencil screen 108.

In the FIGURES 3 and 4 embodiment, the direction of movement of the bottle conveyor is at right angles to the direction of movement of powder conveyor 90, as opposed to the parallel relationship of the FIGURE 1 embodiment. The embodiment of FIGURES 3 and 4 further ditfers from that of FIGURE 1 in that the screen and powder supply are stationary during the decorating operation while the bottle and slotted plate 102 move in translation during the decorating operation.

An exemplary electrical control circuit for the embodiments of FIGURES 3 and 4 is shown in FIGURE 8. Control of pneumatic motor 104 is by a conventional pneumatic system identical to that disclosed in FIGURE 7. In FIGURE 8, the

relays

104R and 104E correspond to the pneumatic connections causing the piston rod of motor 104 to retract (104R) or to extend (104E). Bottle conveyor 110 is driven by a drive motor M5 and the circuit of FIGURE 8 includes two control relays C1 and C2 respectively.

Referring briefiy to FIGURE 4, two limit switches LS1 and LS2 are respectively located to be engaged as a bottle arrives at the decorating location and leaves the decorating location, the decorating operation occurring while the bottle is moving from the position of limit switch LS1 to that of limit switch LS2. Limit switches LS3 and LS4 are located to be engaged when slotted plate 102 is at one or the other end of its limit of movement, limit switch LS4 being engaged by the plate when the plate is ready to begin a decorating stroke, while limit switch LS3 is engaged when the plate reaches the end of its decorating stroke.

As an initial condition, it will be assumed that bottle conveyor 110 is moving to the left as viewed in FIGURE 4 but has not yet arrived at the position of limit switch LS1, and that slotted plate 102 is at its extreme right hand limit of movement as viewed in FIGURE 4, with the plate engaging the striker of limit switch LS4.

With the foregoing conditions, referring to FIGURE 8, control relay C2 is energized because with the plate at its ready position, limit switch LS4 is engaged and its normally open contacts LS4a are closed. A set of normally closed contacts LS3a controlled by limit switch LS3 are in their normal closed condition at this time because the striker of limit switch LS3 is disengaged. Relay C2 is locked in by its controlled lock-in contacts C21; while convey-or drive motor M5 is energized by contacts C2b closed by the energization of control relay C2.

As conveyor 110 advances the bottle into the decorating region, limit switch LS1 is engaged and its contacts LSla close to energize control relay C1 via contacts LS4c (closed because LS4 is engaged at this time by the slotted plate) and normally closed contacts LS2a. Control relay C1, when energized, locks in via its lock-in contact Cla which bypass contacts LSla and LS4a.

Energization of control relay C1 closes its contacts C1b to simultaneously energize voltage sources V1 and V2 and to energize relay 104E to establish the pneumatic connections to motor 104 to cause the motor to drive in a direction extending its piston rod, thereby 8 moving slotted plate 102 to the left as viewed in FIG- URE 4.

The speed of movement of slotted plate 102 and its initial point of starting are regulated in accordance with the movement of the bottle B upon its conveyor so that slot 106 stays in vertical alignment with the axis of rotation of the bottle B and the plate and bottle move in unison from right to left as viewed in FIG- URE 4. Throughout this time, voltage sources V1 and V2 are energized and powder is electrically transferred upwardly through slot 106 and stencil screen 108 to the bottle surface. The bottle is rotated during this movement by virtue of its peripheral contact with the rolling rail 112 (FIGURE 3).

Simultaneous movement of the bottle and slotted plate 102 continue until the bottle conveyor contacts limit switch LS2. Contacting of limit switch LS2 opens the normally closed contacts LSZa, thereby de-energizing relay C1 and by the consequent opening of its contacts C1b de-energizing the two voltage sources and motor control relay 104E. Slightly after the engagement of limit switch LS2 by the bottle conveyor, limit switch LS3 is engaged by plate 102 when the plate reaches the conclusion of its leftward stroke. Engagement of limit switch LS3 opens its contacts LS3a thereby de-energiZing control relay C2 to open contact C2b. However, conveyor motor M5 remains energized and keeps driving via the normally closed bypass contacts LSlb which are closed because the striker of limit switch LS1 is now disengaged by the conveyor.

De-energization of relay C2 closes its normally closed contacts C20 to energize conveyor drive motor M4 and pneumatic motor control relay 104R, energization of this latter relay conditioning motor 104 to drive in a direction retracting its piston rod. Relay 104R and conveyor drive motor M4 remain energized until plate 102 is restored to its ready position at which time contacts C2c open by the energization of relay C2 by closure of contacts LS4a upon the engagement of limit switch LS4 by plate 102.

It will be noted that relay C2 does not become energized until the plate 102 is restored to its ready position. In the event a subsequent bottle B is conveyed by conveyor 110 to the decorating position before plate 102 is restored to its ready position, the conveyor drive motor M5 will be stopped by the opening of contacts LSlb when the conveyor arrives at the beginning of the decorating region. When the plate returns to its ready position, limit switch LS4 is engaged to close contacts LS4a, thereby energizing relay C2 to close contact C2b to start the bottle conveyor motor M5. Contacts LS4a prevent the starting of a decorating cycle unless a bottle and the plate are in their ready positions.

In FIGURE 5, still another form of the invention is disclosed. The FIGURE 5 embodiment is quite similar to the FIGURE 1 embodiment with the exception that an endless belt screen is employed in place of the reciprocating screen of the FIGURE 1 embodiment. In FIGURE 5, an endless conveyor belt is operatively trained about a pair of end rolls 122 and 124, end roll 122 being driven as by a motor M6. A powder hopper 126 is employed to dispense powder 128 in a layer of uniform thickness upon the upper run of belt 120. A plate 130 having an elongate slit 132 therethrough is supported in fixed position above the upper run of belt 120 and an elongate electrically conductive member 134 extends transversely beneath the upper run of belt 120 in vertical registry with slit 132. A bottle conveyor similar to conveyor 38 of FIGURE 1 and designated generally 136 carries bottles B in a direction parallel to slit 132 and perpendicular to the direction of movement of conveyor belt 120. As in the previous cases, the conveyor 1336 supports the bottle for rotation about its longitudinal axis.

A stencil screen in the form of an endless belt 138 is operatively trained around a series of tour guide rollers 140, at least one of the guide rollers being operatively coupled to a suitable drive motor such as M7. As in the previous cases, electric potential sources V1 and V2 are respectively connected to the conductive member 134 and to the bottle, the stencil screen being connected to the electrical ground.

In the FIGURE 5 embodiment, a motor M8 is employed to drive the bottle conveyor, and as in the BIG- URE 1 embodiment, a limit switch LS1 is located to sense the arrival of a bottle in operative registry with the apparatus. Projecting tongues or cars such as 142 are mounted upon the stencil screen so that the arrival of the screen at its ready position relative to the decorating apparatus can be sensed when an car 142 engages the striker of a limit switch LS2. A third limit switch, LS3, is located somewhat in advance of limit switch LS2 for purposes which will become apparent in the description of the control circuit.

The electrical control circuit :for the FIGURE 5 embodiment is disclosed in FIGURE 9. Assuming a bottle is located in operative registry with the apparatus, limit switch LS1 will be engaged and its contacts LSla will be opened, thereby opening the circuit to conveyor drive motor M8. Contacts LSlb will be closed, and assuming the screen is in its ready position with LS2 engaged by an ear 142, contacts LSZa will also be closed, thereby completing a circuit through normal closed contacts LS3a of limit switch LS3 to energize a control relay C1. Contacts Cla and 01b are closed by the energization of relay C1 thereby energizing voltage sources V1 and V2 and powder conveyor drive motor M6 via contacts Cla and energizing screen drive motor M7 via contacts Clb. Relay C1 is locked in by contacts Clc which bypass contacts LSlb and LSZa.

The above conditions remain until the screen is advanced to a position where the striker of limit switch LS3 is engaged by one of the ears 142 on the screen. This engagement occurs after the decorating process has been completed, but before the screen is advanced a complete step to its next ready position. Engagement of limit switch LS3 opens contacts LS3a thereby de-energizing relay C1, opening contacts Cla to de-energize the potential sources V1 and V2 and the powder conveyor drive motor M6.

Engagement of limit switch LS3 also closes its normally open contacts LS3 to energize a second control relay C2 via normal closed contacts LS2c of the now disengaged limit switch LS2. Energization of relay C2 closes its contacts C2a to energize motor M8 to drive the bottle away from the decorating position, at which time contacts LSla close to maintain motor M8 driving upon the later opening of contacts C2a. Relay C2 is locked in by contacts C2c which bypass contacts LS3b. Screen drive motor M7 is energized by the closure of contacts C2b and drives until the screen reaches its ready position, at which time contacts LS2c are opened, de-energizing relay C2 which opens contacts C2c and C2b to stop screen drive motor M7 and transfer control of bottle conveyeor motor M8 to contacts LSla.

Relay C2 is energized during the period necessary for the screen car 142 to advance from engagement with limit switch LS3 into engagement with limit switch LS2. This relatively short time interval is sufl'icient to ener gize bottle conveyor motor M8 long enough via contacts C2a to drive the conveyor clear of limit switch LS1, thereby causing contacts LSla to close before contacts C211 open.

For purposes of illustration, the invention has been described in terms of decorating a cylindrical bottle surface, and is believed apparent that tapered or conical surfaces can equally well be decorated by appropriate modification of the conveyor support yokes. In the case where the bottle cross section is non-circular, as for example elliptical cross section, the support yoke may be modified to reciprocate vertically during the rotation of the bottle to maintain that portion of the bottle surface registered with the slit at a constant distance above the stencil throughout the rotary movement of the bottle.

While various embodiments of the invention have been described in detail, it will be apparent to those skilled in the art that the disclosed embodiments may be modified, therefore, the foregoing description is to be considered exemplary rather than limiting, and the true scope of the invention is that defined in the following claims.

I claim:

1. The method of applying an image-shaped layer of printing powder particles to an article surface which is a surface of revolution comprising the steps of supporting the article for rotation about the axis of its surface of revolution with the axis located above a horizontal stencil screen having an image defining aperture therethrough, positioning a source of printing powder particles beneath said screen in vertical registry therewith, positioning a horizontally disposed plate having an elongate slit therethrough between said source and said screen with said slit extending parallel to said surface and in vertical registry with said, axis, said elongate slit being relatively narrow with respect to said article and having a length at least equal to the length of said image along said axis, applying electric potentials of opposite polarity to said source and said article to electrically charge and attract particles from said source successively through said slit and the aperture of said screen to the surface of said article, moving said article and said screen horizontally relative to each other in a direction normal to said axis and simultaneously rotating said article about said axis to cause the article surface to roll laterally relative to said screen entirely across said image aperture while said electric potentials are applied to said source and said screen, and maintaining said slit in vertical registry with said axis during relative movement between said article and screen.

2. The method as defined in claim 1 wherein the step of positioning said source of printing powder particles comprises the steps of depositing printing powder particles in a layer of uniform thickness upon a horizontal support surface, advancing the support surface with the layer of particles thereon into vertical registry with said stencil screen, and maintaining the screen and support surface against horizontal movement relative to each other during the period of relative movement between said screen and said axis.

3. The method as defined in claim 2 wherein the step of applying electric potentials of opposite polarity to said source and said article comprises the steps of supporting the layer of printing powder particles above an electrically conductive plate, and connecting said plate to a source of electric potential while maintaining said plate in vertical registry with said screen.

4. The method as defined in claim 2 wherein the step of applying electric potentials of opposite polarity to said source and said article comprises the steps of supporting the layer of printing powder particles upon an electrically semi-conductive member, locating a relatively narrow elongate electrically conductive member in a horizontal position beneath said semi-conductive member in vertical registry with said slit, connecting said electrically conductive member to a source of electric potential, and maintaining said conductive member in vertical registry with said slit and said axis during the period of relative motion between said screen and said axis.

5. Apparatus for electrically applying an image-shaped layer of printing powder particles to an article surface which is a surface of revolution comprising a flat stencil screen means having an image defining aperture therethrough, a fiat plate having an elongate slit therethrough underlying said screen means, said elongate slit being relatively narrow with respect to said article and having a length at least equal to the length of said image along the axis of revolution of said surface, movable powder bed support means for positioning a bed of printing powder particles beneath said plate in vertical registry with said screen means, movable article support means supporting an article for rotation about the axis of its surface with the article above said screen means and with its axis located in vertical registry with said slit in said plate and with the surface of the article closest to the plate extending in parallel relationship thereto, support means supporting said screen means for horizontal movement relative to said plate and supported article transversely of the longitudinal extent of said slit to pass said slit beneath said aperture from a location at one side of said aperture to a location at the other side of said aperture, means operable upon relative movement between said screen means and said plate and article support for rotating the article about its axis to cause the article surface to roll laterally relative to said screen entirely across said image aperture with said article support means maintaining the surface of the article closest to said screen parallel therewith and maintaining the article axis and slit in said fixed vertical registry with each other, electric potential means operable when actuated to electrically charge and impel particles in said bed upwardly through said slit and said image aperture to said article surface, and control means operable to actuate said potential means and to simultaneously shift said plate and said screen relative to each other to pass said slit beneath said aperture from one side of said aperture to the other with said axis in fixed vertical registry with said slit during the relative movement between said plate and said screen.

6. Apparatus as defined in claim wherein said screen means comprises an endless belt operatively trained about a series of guide rollers, said belt having a plurality of uniformly spaced image defining apertures therethrough, and means for driving said belt in uniform increments of movement to successively advance the apertures into vertical registry with said bed.

7. Apparatus as defined in claim 5 wherein said plate is mounted in a fixed position, and means operable by said control means for moving said powder bed support means horizontally during relative movement between said plate and said screen means to maintain said powder bed against horizontal movement relative to said screen means.

8. Apparatus as defined in claim 7 wherein said screen means comprises a frame supporting a horizontal stencil screen, and means operable by said control means for driving said screen frame in horizontal reciprocatory movement relative to said plate.

9. Apparatus as defined in claim 7 wherein said powder support means comprises an endless belt conveyor having a horizontally extending run disposed beneath said plate, and means overlying said run of said conveyor belt for depositing printing powder particles in a layer of uniform thickness upon said run in advance of said plate.

10. Apparatus as defined in claim 7 wherein said powder bed support means comprises a reciprocatory plate movable into and out of registry with said stencil screen, and powder supply means for depositing printing powder particles upon said plate in a layer of uniform thickness when said plate is out of registry with said screen.

11. Apparatus for electrically applying an image shaped layer of printing powder particles to a cylindrical article surface comprising an endless belt conveyor having a horizontally extending upper run, means operable to drive said conveyor belt to advance the upper run in a first direction, means adjacent the upstream end of said upper run for depositing printing powder particles thereon in a layer of uniform thickness, a flat plate overlying said upper run and having an elongate slot therethrough extending transversely across said upper run, a stencil screen having an image defining aperture therethrough overlying said flat plate, means for moving said stencil screen horizontally above said slot between a first position wherein the aperture of said screen is located at one side of said slot and a second position wherein said aperture is located at the opposite side of said slot, article support means for supporting an article for rotation about the axis of its cylindrical surface and for positioning said article above said screen with its axis extending horizontally in vertical registry with said slot, electric potential means operable when actuated to electrically charge powder particles in said bed and to impel said particles upwardly through said slot and said aperture to the article surface, means responsive to the location of an article with its axis in vertical registry with said slot for actuating said potential means and for simultaneously actuating said screen driving means to drive said screen between said first and second positions, and means on said screen engageable with said article surface to rotate said article about its axis by horizontal movement of said screen.

References Cited UNITED STATES PATENTS 2,484,671 10/ 1949 Bauman. 3,273,496 9/1966 Melmon. 3,306,193 2/1967 Rarey et al. 3,307,477 3/1967 Booher 10l -1l4 2,940,864 6/1960 Watson. 3,081,698 3/1963 Childress et al. 101l22 3,251,706 5/ 1966 Walkup.

EDGAR S. BURR, Primary Examiner US. Cl. X.R.