Work sheet conveying and housing system and work sheet conveying and housing method

A work sheet conveying and holding method for a work sheet conveying and housing system comprising:

• a work sheet stocker in which a plurality of work sheets can be housed;
• and a work sheet conveying device that conveys a work sheet to said work sheet stocker, said work sheet stocker having:
• a stocker frame having a tray housing portion with a plurality of stages;
• and trays which are provided on the respective stages of said tray housing portion and a position of which can be freely switched between an inner position where said trays are housed in said tray housing portion and an outer position where said tray are drawn out of said tray housing portion, said work sheet conveying and holding method comprising the steps of:
• holding the work sheet by a sheet holder;
• moving said work sheet holder parallel to a position switching direction corresponding to a direction in which said trays are drawn out;
• positioning said trays in all the stages in said work sheet stocker, at said outer position;
• adjusting a height of one or both of said work sheet holders and said work sheet stocker so that the height of said work sheet holder corresponds to a height of an uppermost one of the trays in the plurality of stages located at said outer position;
• simultaneously moving said work sheet holder parallel to said position switching direction to switch a position of the uppermost one of said trays in the plurality of stages located at said outer position, to said inner position and establishing a work sheet placing condition in which said work sheet holding means is positioned above a work sheet placement target tray that is a tray located one stage below said uppermost tray;
• and
• releasing the work sheet by said work sheet holder to release the held work sheet in said work sheet placing condition.