Abstract This invention relates to improvements in display units, and it relates particularly to units in which the display utilizes temperature differences and principally where the temperature difference are made to provide a visual display. The specification discloses a rectangular coordinate printer and plotter incorporating a matrix of semiconductor rectifier junctions connected in rows and columns whereby selected ones of the rectifiers may be rendered conductive. Heat generated in the rectifier is conducted to the surface of a platen where it acts upon a thermally sensitive paper which changes color at the point of heat application. Two forms of platens are illustrated and described. In one the several rectifiers of the matrix comprise discrete units interconnected by conductor deposits and wires. In the other, the several rectifiers are formed as a monolithic structure of semiconductor material.
In a thermal printer: at least two pairs of conductors and at least four unidirectional, semiconductor junction devices of a kind whose temperature increases when conducting electrical currents; a respectively associated one of said devices being connected from each of said first pair of conductors to each of said second pair of conductors, said conductors and said devices forming part of a platen having a printing surface; heat-conducting means for selectively conducting heat from each of said devices to a respectively associated surface area of said platen.
Claim 2
Dependent Claim
21 words
The invention defined in claim 2 in which said heat-conducting means comprises a portion of the material of said semiconductor devices.
Claim 3
Dependent Claim
22 words
The invention defined in claim 2 in which said semiconductor junction devices are formed integrally from a monolithic block of semiconductor material.
Claim 4
Dependent Claim
28 words
The invention defined in claim 2 in which said platen is formed by an integral grid of parallel bars of P-type material overlying parallel bars of N-type material.
Claim 5
Dependent Claim
46 words
The invention defined in claim 2 in which said heat-conducting means comprises a layer of thermal and electrical insulating material and a plurality of spaced heat conductors extending through the layer, each heat conductor being in thermal communication with a respectively associated one of said devices.
Claim 6
Dependent Claim
46 words
A monolithic printing platen comprising an integral grid consisting of a first set of parallel members of P-type material overlying a second set of parallel members of material extending crosswise of said first set and including N-type material at the points of intersection of the members.