Excessive substrate media height detection in a printing apparatus

A direct marking printing system comprising:

• at least one print head for imparting an image onto a media substrate;
• a media transport having a surface for moving a sheet of substrate media along a media path in a process direction past the print head;
• a media hold down for holding media against the media transport surface;
• a substrate media height detector including an elongate detection member spaced a predetermined distance X from the media transport surface and extending over the media transport surface in a cross-process direction, the height detector being disposed upstream of a print head;
• and
• a sensor disposed adjacent to the detection member for sensing deflection of the detection member caused by engagement with the substrate media thereby indicating media having excessive height.

A method of protecting a print head in a printing system comprising:

• transporting a sheet of media along a media path in a process direction;
• detecting media exceeding a predetermined height with an elongate detection member including a portion extending across the media path in a cross-process direction and being spaced from the media transport surface a predetermined distance X, the detection member being movably attached to a support structure, the detection member being deflectable upon engagement with a sheet of substrate media;
• and
• sensing with a sensor the deflection of the detection member by sheet of media exceeding the predetermined height;
• and
• initiating a print head protection response responsive to the sensed deflection of the detection member wherein the sheet of media exceeding the predetermined height is prevented from engaging the print head.