Patent GB-492693-A (GB)
Title: Improvements in or relating to mechanism for feeding or drawing a tape or printed web through a projection field
IPC: G03B21/134
Filed: 1937-03-25
Abstract: 492,693. Optical-projection apparatus. STEVENS, A. H. (Trans-Lux Daylight Picture Screen Corporation) March 25, 1937, No. 8875. [Class 3 (i)] [Also in Group XVI] In apparatus for printing characters in line form transversely of a broad transparent web and moving the web through a projection means, the web is drawn through the projection means in a substantially vertical direction by drawing means situated above the projection means, a retarding means below the latter holds the web flat, the printing means is transversely movable to a servicing position, and the section of the web remaining in the projection means is undisturbed when the printing means is moved to the servicing position. The apparatus is housed in a cabinet C provided with a detachable door d, and comprises a base 1 secured to the bottom of the cabinet, a turntable 2 rotatably mounted on the base, and a standard 4 secured to the turntable and carrying a projector P. Two pairs of legs 6 pivoted on the turntable support a table 7 on which is detachably mounted a printing-device D, such as a typewriter. The printing-device D is shown in the operative position, the legs being connected to the standard 4 by chains 10, and latches 8 on the table 7 engage members 9 on the standard 4 to retain the printing-device in the operative position. To move the printing- device D to the servicing position, the apparatus is rotated about the base 1 to bring the device D opposite the door d, the latches 8 are released, and the device D then moved outwardly to the extent allowed by the chains 10. The printing- device D is of known form comprising a typewheel and coacting inking-roller, and an intermittently-actuated platen bar. The transparent tape or web W is drawn from a reel 20 mounted on one of the legs 6, and extends upwardly between the typewheel and platen bar, through the projector P, between a pair of feed rolls, and then passes through an aperture in the top wall of the cabinet. The projector P comprises a lamp housing 21, a pair of condenser lenses in a chamber 24, a rigid frame 28, and a pivoted frame 36, 45. The frames 28, 36 and 45 carry the web drawing and retarding means, a mirror 47, and objective lens 46. The frame 36, 45 can be swung about pivots to allow the web to be positioned in the projector. The frame 28 carries at the top a transverse shaft having a number of spaced corrugated surfaced rollers secured thereon, this shaft being intermittently driven from the printing- device D at the end of each line-printing operation by means of gear-wheels and a flexible driving shaft. The rollers of the driven shaft co-operate with loosely mounted rollers mounted on the pivoted frame 36, 45 to draw the web through the projector. At the bottom of the frame 36, 45 is a shaft carrying a number of loosely mounted spaced wheels having sharp edges, and these co-operate with a number of weighted fingers 34 to retard the movement of the web. The figures 34 are pivotably mounted at the base of the chamber 24. Instead of fingers 34, a pivoted bar extending transversely of the projector may co-operate with the sharpedged wheels. The driving means between the printing-device and the web drawing means on the top of the projector may be modified. A cam-operated mercury switch is actuated from the printing-device to energize a solenoid which oscillates a pivoted lever provided with a gear segment. The segment meshes with a pinion which is connected through a ratchet-means to the shaft of the web-drawing rollers. Means are provided for preventing retrograde rotation of the driving shaft. A motor 12 for operating the apparatus is mounted beneath the table 7.