Development unit for dry silver recording paper

Claim 2

A developer unit apparatus for dry silver recording paper, which comprises a thin foil of thermally conductive material over the top surface of which the recording paper is passed; and a thermally conductive strip provided with at least one heating element, said strip being in thermal contact with the underside of said foil, wherein the region of thermal contact between said thermally conductive strip and the foil is substantially linear and is transverse to the direction of movement of the recording paper, wherein heating assemblies each including at least one heating element are provided on opposite faces of said thermally conductive strip, and wherein each heating assembly comprises two copper-track elements etched on a strip of epoxy glass fibre, said elements being separated by a thin copper plate and being sandwiched between two phosphor bronze strips.

Claim 3

A developer unit apparatus for dry silver recording paper, which comprises a thin foil of thermally conductive material over the top surface of which the recording paper is passed; and a thermally conductive strip provided with at least one heating element, said strip being in thermal contact with the underside of said foil, wherein the region of thermal contact between said thermally conductive strip and the foil is substantially linear and is transverse to the direction of movement of the recording paper, wherein heating assemblies each including at least one heating element are provided on opposite faces of said thermally conductive strip, wherein each heating assembly comprises two copper-track elements etched on a strip of epoxy glass fibre, said elements being separated by a thin copper plate and being sandwiched between two phosphor bronze strips, and wherein an inward facing surface of each of the heating assemblies is formed by a further strip of epoxy glass fibre.

Claim 4

A developer unit apparatus for dry silver recording paper, which comprises a thin foil of thermally conductive material over the top surface of which the recording paper is passed; and a thermally conductive strip provided with at least one heating element, said strip being in thermal contact with the underside of said foil, wherein the region of thermal contact between said thermally conductive strip and the foil is substantially linear and is transverse to the direction of movement of the recording paper, wherein heating assemblies each including at least one heating element are provided on opposite faces of said thermally conductive strip, wherein each heating assembly comprises two copper-track elements etched on a strip of epoxy glass fibre, said elements being separated by a thin copper plate and being sandwiched between two phosphor bronze strips, and wherein an inward facing surface of each of the heating assemblies is formed by a further strip of epoxy glass fibre.

Claim 5

A developer unit for dry silver recording paper, which comprises a thin foil of thermally conductive material having a curved profile and being arranged to guide said recording paper over its top surface through a curved path; and a thermally conductive strip held in thermal contact with the underside of said foil, the region of thermal contact between said thermally conductive strip and said foil being substantially linear and transverse to the direction of movement of the recording paper, wherein heating assemblies each including at least one heating element are provided on opposite faces of said thermally conductive strip, each heating assembly comprising two copper-track elements etched on a strip of epoxy glass fibre, said elements being separated by a thin copper plate and being sandwiched between two phosphor bronze strips.

Claim 6

A developer unit for dry silver recording paper, which comprises a thin foil of thermally conductive material having a curved profile and being arranged to guide said recording paper over its top surface through a curved path; and a thermally conductive strip held in thermal contact with the underside of said foil, the region of thermal contact between said thermally conductive strip and said foil being substantially linear and transverse to the direction of movement of the recording paper, wherein heating assemblies each including at least one heating element are provided on opposite faces of said thermally conductive strip, each heating assembly comprising two copper-track elements etched on a strip of epoxy glass fibre, said elements being separated by a thin copper plate and being sandwiched between two phosphor bronze strips.

Claim 7

A developer unit apparatus for dry silver recording paper, which comprises a thin foil of thermally conductive material rigidly secured at one end thereof to a support surface, said foil being of curved profile and arranged to guide said recording paper over its top surface through a curved path; and a thermally conductive strip provided with at least one heating element, said strip being located between said support surface and the underside of said foil and being in thermal contact with the underside of said foil, the region of thermal contact between said thermally conductive strip and the foil being substantially linear and transverse to the direction of movement of the recording paper.

Claim 8

A developer unit apparatus for dry silver recording paper, which comprises a thin foil of thermally conductive material rigidly secured at one end thereof to a support surface, said foil being of curved profile and arranged to guide said recording paper over its top surface through a curved path; and a thermally conductive strip provided with at least one heating element, said strip being located between said support surface and the underside of said foil and being in thermal contact with the underside of said foil, the region of thermal contact between said thermally conductive strip and the foil being substantially linear and transverse to the direction of movement of the recording paper.

Claim 9

Apparatus as claimed in claim 4, wherein the thermally conductive foil is in the form of a thin metallic strip.

Claim 10

Apparatus as claimed in claim 5, wherein said thin metallic strip is formed of a stainless steel.

Claim 11

Apparatus as claimed in claim 1, wherein the thermally conductive strip makes a knife edge contact with the underside of the thermally conductive foil.

Claim 12

Apparatus as claimed in claim 1, wherein said thermally conductive strip is formed of copper.

Claim 13

Apparatus as claimed in claim 1, wherein heating assemblies each including at least one heating element are provided on opposite faces of said thermally conductive strip.

Claim 14

Apparatus as claimed in claim 9, wherein the thermally conductive strip has respective ends, and the heating elements are arranged to deliver greater thermal energy at the ends of the thermally conductive strip in order to compensate for the increased thermal losses at these points.

Claim 15

Apparatus as claimed in claim 9, wherein the heating assemblies include a thermocouple which forms part of a temperature control mechanism.

Claim 16

Apparatus as claimed in claim 11, wherein said thermocouple is arranged to provide current to a differential amplifier, the output of which is delivered to a proportional heat drive circuit which controls the power supply to the heating element of the heating assembly.

Claim 17

Apparatus as claimed in claim 9, wherein an electrically insulating, thermally conductive tape is applied between the thermally conductive strip and each of the heating assemblies.

Claim 18

Apparatus as claimed in claim 13, wherein said tape is self-adhesive.