Apparatus for sensing when paper utilized in a printer has been depleted

Abstract

Apparatus adapted for use in printers for indicating when the paper upon which information is to be printed has been depleted. A pivotable sensing member is slightly biased towards a fixed guide member, the two members being adjacent to one another. The sensing member has a horizontal row of protrusions on its inner wall which entend towards the opposing wall of the fixed member. The opposing wall of the fixed member similarly has a horizontal row of protrusions extending towards the sensing member but being aligned between the protrusions on the sensing member. In the situation wherein no paper is introduced between said members, a switch associated with the sensing member provides an indication to control circuiting that no paper is present for printing. When paper is introduced between the protrusions, the slight bias of the sensing member is overcome by particular characteristics of the paper and the sensing member is pivoted away from the fixed member causing the switch associated with the sensing member to change condition and provide an indication to the control circuitry that paper is present between the two members. The protrusions in effect amplify the pivotable motion of the sensing member such that the switch means is responsive to paper of various thicknesses. The sensing member also acts as a paper drag in the case of continuous form, folded paper such that the paper folds conform to the printer platen whereby information can be printed, if required, accurately on the paper fold line.