GB1261216A - Fluid-cooled copying apparatus - Google Patents

Abstract

1,261,216. Contact printing apparatus. MINNESOTA MINING & MFG. CO. Feb. 26, 1969, No. 10297/69. Heading G2A. Radiation from a source 20 passes through a chamber 30 bounded by transparent sides 76, 78, through which a cooling fluid circulates, and in which is mounted a shutter 22 which is moved from a "closed" to an "open" position by the flow of the fluid, and in the reverse direction by reversing the flow of the fluid. The embodiment shown is a photographic contact-printing apparatus, built within a general housing 10. The radiation source is a high-intensity lamp 20, light from which passes through an opening in the main frame 64 to the exposure station. This is formed by a plate 76 of heat-absorbing glass having a quartz platen on its outer face. The original and copy sheets are placed, in contact, against the quartz platen when an exposure is to be made. Behind plate 76 is a narrow chamber 30, bounded on the inner side by a further quartz platen 78. Within chamber 30 is a thin aluminium shutter 22 which can slide vertically from the position shown in Fig. 2, in which it intercepts the light path, to a lower position in it is clear of the light path. The cooling fluid, which may be a liquid fluorocarbon having a boiling point of about 180‹ C., is pumped in at the lower end of the housing, through a spool valve 42. It circulates through conduits formed in the frame 64, passing through chamber 30, and then out again through the spool valve, where it is discharged through a heat exchanger into a reservoir for re-circulation. In the position of Fig. 2, the liquid is passing through chamber 30 in an upwards direction, so that the light-weight shutter 22 is maintained in the "shutter closed" position shown. When a solenoid 40 is energised, the valve 42 is actuated so that the liquid is caused to circulate through a different combination of conduits, which now result in its flowing downwards, through chamber 30. This moves the shutter 22 downwards and out of the light path, so allowing an exposure to take place. On de-energizing the solenoid, the spring-loaded valve returns to its original position, so that the shutter is closed once more. A separate circulation of cooling air for the lamp passes from a blower 46 to an exit opening 48. The lamp is normally maintained at a lowintensity state, until the valve 40 is actuated to open the shutter, the controlling circuit at the same time switching the lamp to its high-intensity or operative state.