| 摘要 |
980,625. Thermographic copying machines. MINNESOTA MINING & MANUFACTURING CO. March 29, 1961 [April 5, 1960], No.11537/61. Heading G2A. In a thermographic copying machine in which a copy is made by exposing an original and a copy sheet, held in contact round a roller, to radiation from a lamp inside the roller, the lamp is retractable from a position close to the roller to a position spaced farther away from it. In the form shown, the original and heat-sensitive copy sheets are fed together into an inlet 64 and guided up towards the printing roller 25. This consists of a thin-walled glass cylinder, within which is mounted a lamp 68 and reflector 67. The sheets pass between this cylinder and a roller 20 of soft rubber, which is slightly flattened at its area of contact with cylinder 25. The sheets then pass through outlet 65. When the sheets enter the apparatus, the leading edge engages a pair of wire bails 79 and pushes them upwards, which operates a switch to energize the lamp. As the trailing edge of the sheets leaves these wires, they fall back to their normal position and the lamp is extinguished. The lamp and reflector can move between the operative position shown in Fig. 2, when they are closely adjacent to the sheets passing between rollers 20 and 25, and a retracted non-operative position. Roller 25 rotates in contact with two smaller rollers 21, 22. The motive power is transmitted via roller 21, which is connected to a motor shaft 41 via a variable speed transmission. The speed is controlled by a U-shaped carrier member 36 mounted for pivotal movement about shaft 41, and movable by a rack 47 which engages with a toothed quadrant 46 forming part of member 36. This is operable from a knob 56 at the front of the device, via a Bowden cable 57, 58. The lamp and reflector are mounted at their ends on pivotal arms, and are normally spring-biased into the operative position of Fig. 2. They are retracted into their non-operative position by a mechanical arrangement of slides and cams, which engage the pivotal arms and tilt them so that the lamp moves away from the paper sheets. This is again controlled from knob 56, which further controls a main switch so that the lamp cannot be energized if the knob is in the "off" position. The reflector 67, which has a narrow opening 82 to concentrate the radiant energy from the lamp along a narrow band, is of a special construction giving improved reflection of heat and infra-red radiation. The printing roller has a slightly concave profile taken along its longitudinal axis, this assisting in the prevention of wrinkling as the two sheets in contact pass through the machine. Specification 980,626 is referred to. |
