TECHNICAI. FIE P

The present invention relates to a silk-screen printer, or screen process printer, comprising a printing table, a printing frame and a squeegee arrangement, in which machine print material is laid-on, positioned, printed and laid-off manually, although said printer can readi¬ ly be made semi-automatic, such that print material is positioned and printed automatically, with the aid of simple means.

The invention relates in particular to improvements in silk-screen printers of the kind which comprise a flat printing table intended for supporting print material in a registered position, such as board on which a circuit is to be printed or has been printed, a print¬ ing frame disposed above the printing table, and a stencil-carrying printing frame, said stencil being provided with perforations corresponding to the pattern to be printed, and a squeegee arrangement comprising a squeegee blade which, when the squeegee arrangement moves across the upper surface of the stencil, func¬ tions to transfer printing paste located on the upper surface of said stencil through the perforations there¬ in, so as to form a printed pattern on the upper sur¬ face of the print material resting on the printing table.

More particularly, the invention provides an improve¬ ment in silk-screen printers in which the printing frame is pivotally mounted at one end thereof for pivo¬ tal movement relative to a printer stand, so that the printing frame can be brought to an inclined position which will facilitate removal of printed material and

the process of laying-on and registering of print ma¬ terial intended to receive fresh print.

BACKGROUND ART Silk-screen printers of this kind are known in many different forms. Pivotal mounting of the printing frame at one end thereof is particularly appropriate in the case of manually operated silk-screen printers.

In the case of these known silk-screen printers, it has been necessary to pivot the printing frame through an angle of 40 ^* or more, in order to bring the frame to an open positio in which it will not obstruct and prevent simple and precise laying-on of fresh print material in a registered position on the printing table.

It is also known to place the registering devices, in the form of registering pins, belonging to the printing table adjacent that edge of the table which is remote from the pivotal attachment of the stencil.

Endeavours have been made to expose the registering devices on the printing table, and therewith facilitate application of fresh print material, in the absence of a pivotal printing frame. These endeavours have inclu¬ ded the proposed use of various devices for moving the printing table horizontally into a printing position and to a position in which printed material can be removed and to a position in which fresh print material can be laid-on and brought to a registered position.

SUMMARY OF THE PRESENT INVENTION

TECHNICAL PROBLEMS When considering the prior state of the art as descri- bed above it will be seen that a technical problem is

one of providing a silk-screen printer, particularly a manually-operated printer or a semi-automatic printer, in which the printing frame is pivotal in relation to a printer system (through an angle of 40° or more) which has created the need for sufficient space to enable printed material to be removed from the printer and fresh print material to be positioned therein, without needing to pivot or rotate the printing frame through more than half the pivot angle earlier known.

A further technical problem is one of providing a silk- screen printer which affords the same, or essentially the same degree of access as that afforded by a hori¬ zontally reciprocatingly movable printing table, so as to enable printed material to be removed from the table and fresh print material to be placed in a registered position on said table, without requiring therefor a large free surface in front of the printer for accom¬ modating the reciprocating movement of the table.

It will also be seen that a technical problem is one of realizing the advantages that are afforded by unique coaction and mutual coupling between the printing frame and the printing table, such that rotation of the prin- ting frame from a horizontal position to a slightly inclined position can cause the printing table to move horizontally, or at least substantially horizontally in a direction away from the printing-frame pivot attachment.

It will also be seen that a technical problem, requir- ing qualified technical perception, is one of providing a joint-coupling which, for the aforesaid purpose, solely requires the stencil frame to pivot through an angle of less than 30°, preferably between 10 and 15 ^β .

.and therewith cause the printing table to move in a direction away from the printing-frame pivot attachment through a distance so adapted that sufficient space is provided for enabling printed material to be removed 5 and fresh print material to be placed in a registered position ocularly _* ^

It will also be seen that a technical problem is one of providing a simple construction which will enable the 0 printing table to be moved horizontally away from the printing-table pivot attachment or, with minor modifi¬ cations to the printer, to cause the printing table to move along a downwardly inclined path away from said printing-frame pivotal attachment. 5

It will also be seen that another technical problem is one of providing, when desired and with the aid of simple means, for movement of the printing table away from the aforesaid pivotal attachment, such as to cause 0 that part of the printing table distal from said pivo¬ tal attachment to move in an outwardly/downwardly path.

It will also be seen that a technical problem resides in realizing the advantages afforded from a construc- 5 tive aspect when the printing table is flat and the aforesaid movement can be effected along parallel guides pr gui e rails.

A further technical problem is one of realizing that 0 said joint-coupling between pivotal movement of the printing frame and movement of said printing table can • be readily effected with the aid of mechanical compo¬ nents. This joint-coupling can also be effected by electrical drive means or in some other way, with the 5 aid of a device which is operative to detect the

prevailing pivot angle and to control a unit for activating movement of the printing table.

SOLUTION

5 The present invention provides a solution to one or more of the aforesaid technical problems associated with a silk-screen printer of the kind which comprises a flat printing table intended for supporting, in a .registered position, material which is intended to 0 receive print, particularly stiff print material such as board on which a circuit is to be printed, a print¬ ing frame arranged above the printing table and holding a stencil which is provided with perforations corres¬ ponding to the pattern to be printed, and a squeegee 5 arrangement comprising a squeegee which, when moved manually over the upper surface of the stencil, func¬ tions to transfer printing paste located on the upper surface of the stencil through the stencil perforations such as to form a printed pattern on the upper surface 0 of the print material registered in position on the printing table, and in which printer the printing frame is mounted at one end thereof for pivotal movement relative to a printer stand, such that the frame can be brought to an inclined position and therewith facili- 5 tate removal of printed material and laying-on and registering of fresh print material intended to receive print.

It is proposed in accordance with the invention that in 0 the case of such printers the printing frame and print¬ ing table are jointly coupled so that upward pivoting , of the printing frame from a horizontal to an inclined position will cause the printing table to move in a direction away from the printing-frame pivot 5 attachment.

In accordance with proposed embodiments lying within the scope of the inventive concept it is proposed that said joint coupling is active when pivoting the print- ing frame, or stencil frame, through an angle smaller than 30°, preferably an angle of 10-15".

It is also proposed that the printing table shall be able to move strictly horizontally in a direction away from the printing-frame pivot attachment.

In accordance with a further alternative, it is propo¬ sed that the printing table shall be able to move hori¬ zontally away from the printing-frame pivot attachment and also in a downwardly inclined path.

Alternately, that part of the printing table distal from the pivot attachment can be caused to move hori¬ zontally outwards and slightly downwards, while that part of the printing table located adjacent said pivot attachment performs a strictly horizontal movement.

In that particular case when the printing table is flat, it is proposed that said movement is effected with the aid of parallel guides or guide rails along which the Tαiown printing-table bearings are able to move.

The joint-coupling between pivotal movement of the printing frame and movement of the printing table is preferably achieved with the aid of purely mechanical components. For instance, this joint-coupling can be achieved with the aid of a pinion or like gearwheel in coaction with a rack mounted on one edge surface of the printing frame.

The joint-coupling may also be achieved with the aid of electrical drive means, in which case a device is pro¬ vided for detecting the pivot angle of the printing frame, and in that the arrangement includes a unit for activating movement of the printing table, and that the position of movement of the printing table is clearly determined by the prevailing pivot angle.

APV TAgBS

The advantages primarily afforded by the inventive silk-screen printer reside in the provision of condi¬ tions which enable sufficient space to be readily pro¬ vided for the removal of printed material and for the laying-on and registering of material intended to re¬ ceive print, i.e. print material, while rendering it unnecessary for the printing frame to be inclined at a large angle of inclination with the accompanying risk of highly viscous printing paste running along the stencil. Furthermore, the invention provides different possibilities of mutually coupling the pivotal movement of the printing frame with the movement of the print¬ ing-table and therewith the respective movement posi¬ tions thereof, with the aid of purely mechanical σom- ponents, or with the aid of electrically driven units, or in some other way.

The primary characteristic of an inventive silk-screen printer are set forth in the characterizing clause of the following Claim 1.

BRIEF DESCRIPTION OF THE DRAWINGS

A number of embodiments at present preferred and ex¬ hibiting features characteristic of the present inven- tion will now be described in more detail with

reference to the accompanying drawings, in which;

Figure 1 illustrates a known silk-screen printer comprising a fixed printing table and a printing frame which is mounted at one end het&όf for pivotal movement relative to a printer stand;

Figure 2 illustrates a first embodiment of an inventive silk-screen printer; figure 3 illustrates a second embodiment of an inven- tive silk-screen printer;

Figure 4 illustrates schematically the joint coupling of printing frame and printing table, effected with the aid of purely mechanical components; and Figure 5 illustrates corresponding joint coupling of the printing frame and printing table with the aid of electrically driven units.

DESCRIPTION OF EMBODIMENTS AT PRESENT PREFERRED Figure 1 is a side view, highly simplified, of a silk- screen printer 1 having a flat printing table 2, which is intended to support, in a registered position, mate¬ rial 3 intended to receive print, referred to as print material, a printing frame 4 which is mounted above the table 2 and has stretched therein a stencil 5. The stencil 5 is provided with perforations in accordance with the pattern to be printed, and a squeegee arrange¬ ment 6 is arranged for movement across the upper sur¬ face of the stencil 5 to the right in Figure 1. The squeegee arrangement includes a squeegee rubber 6a which functions to transfer printing paste located on the upper surface of.the stencil and moved in front of the squeegee rubber 6a, through the stencil perfora¬ tions such as to form a printed pattern on the upper surface of the print material 3 resting on the printing

table.

One end 4a of the printing frame 4 is mounted on a pivot journal 7 for pivotal movement in relation to a printer stand 8, so that the frame can be brought to an outwardly inclined position 4' shown in broken lines in Figure 1, therewith facilitating removal of printed material 3 and the laying-on and registering of mate¬ rial intended to receive print.

As will be seen from Figure 1, the printing table 2 is fixed in relation to the stand 8, and consequently the printing table will not move when the printing frame 4 is raised to the position 4' shown in broken lines, or lowered to the position 4 shown in full lines. In the case of this known embodiment, the pivot angle "a" is normally between 40 and 50°, so as to provide suffi¬ cient space between printing table 2 and printing frame 1 in position 4' for printed material to be removed and fresh print material to be positioned ocularly rela- tively to fixed registering devices, in the aforesaid manner.

The present invention enables the same extent of ac¬ cess, or at least substantially the same degree of access to be obtained without needing to pivot the printing frame to a position as high as that shown in Figure 1, and enabling the pivot angle to be reduced by at least half, say to an angle of 10 and 15°.

In the case of the embodiments illustrated in Figures 2 and 3, when respective printing frames are horizontally positioned, in the manner illustrated in Figure 1, respective printing tables 2 will take the position illustrated in Figure 1.

However, Figure 2 shows the frame-* 4 in a raised posi¬ tion 4' and the printing table 2 in a laterally dis¬ placed position 2'.

Thus, Figure 2 shows the printing frame 4 in the posi¬ tion 4', where the printing table 2 in its position 2' receives fresh material 3' which is intended to receive print.

As will be seen from Figure 2, the printing frame 4 and the printing table 2 are mutually coupled, or jointly coupled, such that rotational movement of the printing frame from the horizontal position 4 to the inclined position 4', illustrated by an angle "c", will result in movement of the printing table 2 in a direction away from the pivotal attachment 7 of the printing frame, through a movement path referenced "d".

The joint-coupling is particularly operative during pivotal movement of the printing frame through an angle of less than 30 ^* , preferably through an angle of bet¬ ween 10-15", which means that the earlier known, re¬ quisite pivotal angle "a" shown in Figure 1 is at least halved.

Figure 2 shows the printing table 2 in a position 2', in which the table has moved horizontally, in a straight from the printing-frame pivotal attachment 7.

Figure 3 illustrates that the printing table can be moved in a downwardly sloping path away from the print- ing-frame pivot attachment 7.

It will also be seen from Figure 3 that in position 2" of the printing table 2, particularly with regard to

the table jjart 2"a distal from the pivot attachment 7, the table will move outwardly/downwardly, whereas the part 2"b of the table adjacent said pivot attachment 7 will move in a straight, horizontal path.

The horizontal movement according to Figure 2, or the outward/downward movement according to Figure 3, can be effected by moving the printing table 2 to its respec¬ tive positions 2' or 2" with the aid of parallel guides or guide rails not shown. It will be understood that such guide rails may have a curved configuration such that the outward/downward movement performed by the table part 2 ⁿ b, will, nevertheless, be smaller than the movement performed by the table part 2"a.

For the purpose of enabling print material 3' to be registered in relation to the position 2 ' or 2" of the printing table 2, the material 3' is provided with a plurality of holes 10 and the printing table 2 is prσ- vided with pins 11 corresponding to said holes. Each of the pins is dimensioned to coact with respective holes 10, with a good fit. At least two such registering locations, or pins 11, are required in order to poεi- tionally register the material 3' correctly.

Joint-coupling of the rotary movement of the printing frame and movement of the printing table can be effec¬ ted with the aid of mechanical components. Accordingly, Figure 4 illustrates in perspective an arrangement in which a flexible rod 12 is mounted adjacent to or on the pivotal attachment 7 on the frame 4, and the free end of said rod is intended to fit through a hole 13 in a pinion 14, the rotational axis 15 of which extends vertically.

The teeth 16 of the pinion 14 mesh with a rack ^.at¬ tached to one side-surface of the printing frame 4. If it is assumed that Figure 4 shows the position illu¬ strated in Figure 2, it is obvious that rotation of the printing frame from the position 4' to a horizontal position 4 will cause the rod 12 to move to the left in Figure 4, therewith rotating the pinion 14 anticlock¬ wise and moving the printing table 2 to the left in the figure through a distance which is greater than that afforded by pivoting the printing frame 4.

Figure 5 illustrates an alternative joint-coupling arrangement. This arrangement is electrically operated and incorporates a device 20 which detects the pivot angle ^M c" and, in response to the value of "c" activa¬ tes a drive unit 21 which functions to energize a unit 22 for activating movement of the printing table, such that the position 2' or 2" of the printing table 2 will be clearly determined by a prevailing, final pivot- angle ^M c ^M .

It is proposed that the detecting device 20 is con¬ structed to generate a voltage whose level is deter¬ mined proportionally by the value of the pivot angle, and that the drive unit 21 senses this voltage and produces a clearly defined signal corresponding to said voltage value, this signal being delivered to the unit 22 and thus causing the printing table to be moved through a distance "d" corresponding directly to the amplitude value of the signal.

The proposed embodiment enables the unit 20 to be rea¬ dily set so that movement of the printing table 2 will commence when the angle "c" exceeds a given limit value, say 2-5 ^* .

As will be understood, the inventive concept also in¬ cludes the embodiment in which the printing frame must be raised to or beyond a predetermined value, at which value the unit 21 is activated so as to, in turn, ac¬ tivate the unit 22 and cause the printing table 2' to move from the position shown in Figure 1 to the posi¬ tion shown in Figure 2, alternatively to the position shown in Figure 3, without further activation of the printing frame.

There is nothing to prevent the printing frame from being movable to a height greater than the height il¬ lustrated in Figure 2 and 3, but without corresponding movement of the printing table.

The invention is therefore not restricted to the afore- described and illustrated exemplifying embodiments, since many modifications can be made within the scope of the inventive concept as illustrated in the following Claims.