GB1254706A - Developing apparatus - Google Patents

Abstract

1,254,706. Electrically heated drums. MINNESOTA MINING & MFG. CO. 22 Nov., 1968, No. 55592/68. Heading H5H. [Also in Division G2] Heat-sensitive sheets are developed by passage through developing apparatus consisting of a roll 15 heated by a heater, a cylindrical sleeve 19 thereof having perforations 16, a manifold allowing the application of positive and negative pressures to the perforations, and fixed guides 64 provided adjacent to the surface of the roll and so spaced therefrom as to be out of contact of the sheet when the sheet is held on the roll by the negative pressure. Axially extending passages 18 connect the perforations with the manifold, the manifold consisting of two arcuate grooves formed in manifold members disposed at each end of the roll. The roll is heated by resistance wire sheathed between glass fibre reinforced silicone rubbers layers forming a blanket 21. Thermistors or bimetal thermostats may be used to control the temperature of the drum but preferably thermostatic switches are actuated by the expansion of metal bars associated with the drum structure. A sheet plated on a pivotally mounted spring-loaded plate 72 is aligned with a fixed guide plate and then fed between rollers 62, 63. The negative pressure produced in the perforations is sufficient to hold the sheet in contact with the heated roll, which contact is maintained for 225 degrees rotation of the roll. Positive pressure is then applied to the sheet which passes out of the machine over a discharge plate 68. Guides 64 are disposed in a helical path to minimize axial temperature variations.