Importance

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Abstract

An arrangement in a silkscreen printer for positioning a second pattern (4b) deriving from a first pattern (4a) provided on a stencil (4) in relation to material (2) to be printed while using a first memory arranged to store data relating to the desired position of the second pattern in relation to a reference point. The material (2) on to which the second pattern (4b) is to be printed is displaced to a printing position, in which means (5, 5') are arranged to evaluate the true position of the material. In addition means are provided for evaluating the discrepancy which would occur if the second pattern (4b) were to be applied to the material (2) in its present position. Any deviation between the true position and the desired position is evaluated and when a deviation is found to exist a stencil-holding frame (3) and/or a printing table and/or the material is, or are, displaced, or brought in some other way to a position determined by the magnitude and directional sense of the deviation, so that when applying the first pattern (4a) to the material (2) the transfer pattern (4b) is printed on the material in a position in which full or satisfactory compensation has been made for the previously established deviation. The position of the material can be evaluated with the aid of index marks (2') or part of a previously printed pattern. The position of the material (2) and/or its pattern is, or are, evaluated with the aid of one or more optical scanning and sensing means (5,5'), preferably evaluating the position of index marks. The scanning signals (5a) obtained from the optical scanning and sensing means (5) are fed to a first unit (34) which stores scanning signals for each line in real time. These scanning signals are evaluated by a processor (2) which restructures the signals to a different form, these restructured signals being stored in a second memory (35). A stencil frame (and/or material to be printed) is arranged for displacement by means of three stepping-motors or like devices, and evaluated and calculated displacement values for each of these stepping-motors are applied thereto simultaneously and/or substantially simultaneously.

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First Claim