MATERIAL INTENDED FOR PRINTI G

TECHNICAL FIELD

The present invention relates to a device for holding material intended to receive print, both before and during a printing sequence, and particularly to a device which is intended to hold said material firmly against a printing table forming part of a silk-screen printer through subpressure action.

The upper surface of the printing table is configured with one or more channels which function to hold one or more means for registering the print material.

BACKGROUND ART

Various kinds of holding devices are known to the art for holding print material in a registered position on the'printing table of a silk-screen printer, with the aid of subpressure action.

Thus, it is known to perforate the upper surface of the printing table with small holes in close contiguous relationship and to hold the print material firmly on the printing table through subpressure action.

Although this arrangement is particularly adapted to hold thin print material, it will obvious that such an arrangement can also be used to hold rigid or stiff print material.

An example of the earlier standpoint of techniques in this respect is illustrated and described in UK Patent Specification 1 193 133, according to which different

sections of a printing table are exposed to subpressure sequentially, through valve means.

It is also known, particularly in printers intended for printing stiff print material, such as circuit board, to mount on the printing table registering devices which are connected to activating devices. These devi¬ ces function to hold the material in a registered posi¬ tion on the printing table during a printing sequence.

An example of the earlier standpoint of techniques in this respect is illustrated and described in US Patent Specification 3,536,004.

Also known to the art are various printing-table con¬ figurations having channels formed in the upper sur¬ faces thereof, in which holding devices are mounted for registration of print material, said devices having the form of pins, studs or the like intended to coact with corresponding holes in the stiff material to be printed upon.

Finally, it can be mentioned that it is known to pro¬ vide the printing table with registering devices in the form of suction cups which communicate with a subpres¬ sure source and with the aid of which stiff print mate¬ rial is held firmly against the printing table of a silk-screen printer.

SUMMARY OF THE INVENTION

TECHNICAL PROBLEMS When considering the.present state of the art, as de¬ scribed above, it will be seen that a technical problem resides of providing, with the aid of simple means, conditions such that when registering print material on

a printing table with the aid of registering devices intended herefor, the print material can be held firmly on said table with the aid of suction cups located in the immediate vicinity of said registering devices, thereby enabling conditions to be provided which will guarantee coaction between the registering devices, e.g. in the form of a pin and a hole, even should the print material curve or bend.

/• It will also be seen that a technical problem resides in the provision of conditions such that the channels formed in the printing table are able to accommodate a holder for one or more suction cups, such that respec¬ tive holders can be moved along said channels to a position in which they coact with the print material.

It will also be seen that a technical problem resides in realizing that the subpressure source applied throu¬ gh the suction cup in said holder shall be capable of holding the material in a registered position both prior to and during a printing sequence.

Another technical problem is one of realizing that the holder must be configured so as to enable said holder to be locked in a desired position with the aid of locking means acting between the holder and the printing table.

When respective registration devices comprise holders inserted in the channel and provided with a pin dimen¬ sioned for measurement-precise coaction with a hole formed in the material and when said print material comprises a plate or board intended for a printed cir¬ cuit has a tendency to curve or bend when being regist- ered, a technical problem resides in the ability of

providing means which will ^■ »guarantee precise registra¬ tion of the print material in relation to the printing table through the agency of registration devices, by placing the suction cup or cups in the vicinity of said registering devices.

It will be seen that another technical problem is one of realizing the advantages afforded by permitting the ^requisite suction-cup holder and the requisite pin-holder to form an integrated unit.

In addition, another technical problem is one of reali¬ zing the advantages that are afforded when the channel has a given cross-sectional shape which conforms with a cross-section part of the holder and a further cross- section part for accommodating one or more pipes or hoses connected to one or more suction cups.

It will also be seen that a qualified technical problem is one of realizing the advantages that are afforded when said further cross-section part has the form of two partrcircular slots located on a respective side of the lower part of said cross-section part, for the purpose of accommodating conduits, particularly plastic hoses.

It will also be seen that a predominant technical pro¬ blem is one of realizing the additional advantages afforded when two or more suction cups are mounted in one and the same holder, such as to enable said pin to be arranged between respective suction cups.

Another technical problem, related to one or more of the aforesaid technical problems, is one of realizing the advantages that are afforded when the uppermost

surface of the suction cup can be terminated short of the upper surface of the printing table, in the event of deficient coaction with the print material, said distance between said surfaces preferably lying within well defined limits.

SOLUTION

The present invention relates to a device for holding print material against a flat printing table forming part of a silk-screen printer, with the aid of subpres¬ sure action, the upper surface of said printing table being configured with longitudinally extending channels intended for holding a print-material registering device, such as a pin.

In the case of an arrangement of this kind it is pro¬ posed in accordance with the invention that said chan¬ nels have arranged therein a holder for holding one or more suction cups; that said holder is displaceable in said channel to a position in which said holder coacts with the print material; and in that the suction cup is coupled to a subpressure source operative to hold the material in a registered position prior to and/or during a printing sequence.

In accordance with embodiments that lie within the scope of the inventive concept, it is further proposed that the holder can be locked in said position with the aid of locking means acting between the holder and the printing table.

It is also proposed that the registering device com¬ prises a holder inserted in said channel and provided with a pin dimensioned for measurement-precision coac- tion with a hole provided in the print material.

Preferably, the suction-cup holder and the pin-holder form an integrated unit.

According to one embodiment, the channel has a cross- section which at least conforms to a cross-section part of the holder, and a further cross-section part for accommodating one or more conduits intended for connec¬ tion to one or more suction cups, the conduits optionally being arranged in said channels.

According to another embodiment it is proposed that the further cross-section part has the form of two part- circular slots located on a respective side of the lower part of the cross-section part.

Preferably, two or more suction cups are provided in one and the same holder, in which case said pin is preferably disposed between respective suction cups.

Two or more slots are positioned ^' parallel or obliquely to one another in the upper surface of the printing table, thereby enabling the holders to be moved in accordance with the prevailing format of the material intended to receive print. Finally, the invention en- ables the position of the uppermost surface of the suction cup to be adjusted so as to be located at a given distance from the upper surface of the printing table when coaction with the print material is suffi¬ cient, this distance preferably being less than 0.5 mm and greater than 0.1 mm.

ADVANTAGES

Those advantages primarily afforded by the inventive arrangement reside in the provision of conditions in which rigid material which is to receive print, such as

circuit board or circuit plate, can be registered readily with the aid of mechanical registering means, with the aid of holes formed in the print material and pins related to the printing table, and therewith create conditions which will enable said board or plate to be registered in position even should said board or plate be pronouncedly curved, by positioning additional registering means, such as suction cups, in the immedi¬ ate vicinity of the first-mentioned registering means.

The primary characteristic features of an arrangement in accordance with the present invention are set forth in the characterizing clause of the following Claim 1.

BRIEF DESCRIPTION OF THE DRAWINGS

An exemplifying embodiment of an inventive arrangement having the characteristic features significant of the present invention will now be described in more detail with reference to the accompanying drawing, in which: Figure 1 illustrates in perspective a silk-screen printer provided with a flat printing table configured with two mutually parallel channels in which four holders are mounted; Figure 2 is a perspective view of a first embodiment of a holder provided with a pin and a suction cup; Figure 3 is a side view of the holder illustrated in

Figure 2; Figure 4 is a sectional view of part of the printing table, and illustrates the cross-sectional area of the channel; and Figure 5 is a perspective view of a second embodiment of a holder provided with one pin and two suction cups.

DESCRIPTION OF EMBODIMENTS AT PRESENT PREFERRED Figure 1 is a perspective view of a flat printing table 1 which is intended for a silk-screen printer and which is configured with two mutually parallel channels 2, 3. Mounted in respective channels 2, 3 are holders 4, 5, 6 and 7, which together with print-material registering means are operative to hold print material 8 in a flat, registered position relative to the printing table 1. r Since the holders 4, 5, 6 and 7 are mutually indenti- cal, only the holder 4 will be described in detail with reference to Figures 2, 3 and 5.

It will be understood that reference to four holders each provided with a respective pin does not constitute a restriction of the inventive function, since fewer or more holders can be provided, depending upon the thick¬ ness and shape of the print material.

In the following solely two holder embodiments are described, although it will be understood that more embodiments are conceivable.

The channels 2, 3 are intended to receive one or more holders, in the illustrated embodiments two holders, each having a suction cup 10. The holder 4 is mounted for movement along the channel 2, so as to enable the holder to be brought to a position in which it coacts with the print material 8.

The holder 4 can be clamped against a wall-part 23, 24 of the channel 2 with the aid of an excentric device 15 (not shown in detail), thereby enabling the holder to be secured selectively along the channel.

The longitudinal extension of the holder 4'is preferab¬ ly parallel with the edge-part of the print material, and preferably outside the boundaries of the circuit printed on said material.

The suction cup 10 is connected to a source of subpres¬ sure, via a connection 11, this subpressure being in¬ tended to hold the print material 8 in a flat, registe¬ red position before and/or during a printing sequence.

In the case of the illustrated embodiment, the registe¬ ring device comprises a pin-carrying holder inserted in said channel and a hole formed in the print material, the pin 12 of said holder being dimensioned for measurement-precise cooperation with the hole 13 formed in the print material 8.

In the Figure 2 embodiment the suction-cup holder and the pin-holder have the form of an integrated unit, thereby enabling the suction cup 10 and the pin 12 to be located very close to one another, while enabling the suction cup 10 to coact with the undersurface of stiff print material, e.g. printed circuit board or plate, within a margin or an edge-region in which the printed circuit is not present.

Figure 4 illustrates the cross-sectional shape of the channel 2 provided in the printing table 1.

It will be seen from Figure 4 that the cross-sectional shape of the channel, 2 conforms with the cross-section part of the holder and a further cross-section part for accommodating one or more conduit means connected to one or more suction cups.

The further cross-section part has the form of two part-circular slots 20, 21, located on a respective side of the bottom part of the cross-section part.

As illustrated in Figure 5, it is particularly proposed that two or more suction cups are mounted in one and the same holder. In this regard, the pin may be dis¬ posed between respective suction cups or by the side of -said suction cups.

In the Figure 5 illustration, two suction cups 10, 10' are each mounted in a respective recess, and an excen- tric device 15' can be placed in a recess. The Figure also shows the pin 12' in coaction with a recess.

The recesses are of mutually the same configuration and consequently the illustrated order can be changed selectively, although with the position of the excen- tric device 15' clearly defined.

Although the Figure 1 embodiment includes two mutually parallel channels, it will be understood that it lies within the scope of the invention to provide two or more mutually parallel channels or one or more channels which are positioned obliquely to one another.

As illustrated in Figure 3, the uppermost surface 10a of the suction cup shall be positioned at a distance "d" from the upper surface la of the printing table when coaction with the print material is deficient, this distance being smaller than 0.5 mm and greater than 0.1 mm.

The invention thus proposes a combined coaction between a pin and a hole for registering print material and for

holding the material against a flat printing table with the aid of a subpressure.

It will be understood that the invention is not res¬ tricted to the aforedescribed and illustrated exempli¬ fying embodiments thereof and that modifications can be made within the scope of the inventive concept as defined in the following Claims.