A method for printing inks or pastes on a photovoltaic cell or wafer on shuttles on a rail in a automatic production plant, the method comprising:
- loading the photovoltaic cell or wafer at a loading station, the loading station having at least one container of the photovoltaic cell or wafer, the step of loading comprising automatically individually extracting the photovoltaic cell or wafer from the at least one container and laying the extracted photovoltaic cell or wafer onto a conveyor belt;
- translating the extracted photovoltaic cell or wafer on the conveyor belt below a vision system to determine damaged photovoltaic cell or wafer and undamaged photovoltaic cell or wafer;
- picking the undamaged photovoltaic cell or wafer with a robotic picking device and aligning the undamaged photovoltaic cell or wafer in a desired orientation on an equipped tray, the equipped tray having a vacuum and a fiducial reference and a centering device, the equipped tray being removably positioned in or on a shuttle on a rail with a linear motor so as to be in a loading waiting position;
- discarding the damaged photovoltaic cell or wafer;
- translating the photovoltaic cell or wafer on the shuttle to another vision system, the vision system checking alignment of the photovoltaic cell or wafer on the equipped tray relative to the fiducial reference;
- vacuum securing the photovoltaic cell or wafer onto the equipped tray and simultaneously transferring the shuttle from the loading station;
- orienting a printing screen with a silk-screen printhead so as to align the printing screen relative to the position of the photovoltaic cell or wafer on the equipped tray, the orienting of the printing screen being in accordance with saved calibration parameters of the printhead, saved calibration parameters for the equipped tray, saved calibration parameters for the printing screen, information received from the another vision system as to the position of the photovoltaic cell or wafer on the equipped tray, an image to be printed of the printing screen, and information received from a post-printing vision system;
- translating the shuttle to below the printhead so that the photovoltaic cell or wafer is in a printing position in correspondence to the oriented printing screen;
- holding and lifting the equipped tray from the shuttle up to a printing height by pushers, the pushers having a centering system that is calibrated with respect to the position of the printing screen, the pushers being operated by vertical linear motors so that the pushers engage in pairs at four corners of the equipped tray so as to enable oscillation or tilting of the equipped tray around a horizontal axis orthogonal to an advancing direction of a printing doctor blade in the printhead, a pair of the pushers having a spherical head that is rotatable and another pair of the pushers supporting the printing doctor blade so as to enable relative sliding and an angle between a surface of the equipped tray and the surface of the printing screen upon a change a position of the printing doctor blade during a printing stroke;
- gradually and progressively inclining the equipped tray during printing by two pairs of the pushers having axes thereof controlled and coordinated with a movement of the printing doctor blade, the printing doctor blade moving vertically along a stroke thereof by a pair of motors;
- lowering the equipped tray at an end of the stroke of the printing doctor blade by the pushers back to a horizontal position until the equipment tray engages with centering pins of the shuttle;
- translating the shuttle to at least one automatic vision system so as to obtain an image and to control the printed cell, the at least one automatic vision system having a high-definition line scan camera that scans a surface of the equipped tray,
- automatically sending the image of the printed photovoltaic cell or wafer for printing quality control and to determine whether or not to continue the process and to determine a position of the printed image with respect to the printed photovoltaic cell or wafer and to correct the saved calculation parameters of the printhead, the equipped tray and the printing screen;
- moving the shuttle to an unloading station such that the printed photovoltaic cell or wafer is at an unloading position;
- lifting the printed photovoltaic cell or wafer from the equipped tray, the lifting being by a lifter passing through sliding pins with a suction cup at a top thereof, the suction cup holding the printed photovoltaic cell or wafer during the step of lifting;
- and
- unloading the printed photovoltaic cell or wafer with a fork at the unloading station, the fork being inserted below the photovoltaic cell or wafer so as to lift, disengage and transfer of the printed photovoltaic cell or wafer by control of an overlooking vision system, the printed photovoltaic cell or wafer being moved onto a transport system so as to be removed from the unloading station.