Patent GB-874356-A (GB)
Title: Removable roll-film adapter
IPC: G03B19/04
Filed: 1959-08-26
Abstract: 874,356. Photographic roll film adapters. KARPF, N., [trading as LINHOF, NIKOLAUS KARPF KOMM.-GES., PRAZISIONS-KAMERA-WERKE.]. Aug. 25, 1959 [Sept. 16, 1958], No. 29060/59. Class 98(1) In a removable roll-film adapter for cameras with ground glass focusing screens, which adapter contains film feed means, indicating means for the film feed and a feed lock, the roll film runs over a measuring roller which drives a counter comprising the indicating means through a first device which, when the adapter cover is open and a counter locking pawl is thereby released, allows the counter to spring automatically back to its starting position, and a quick-feed lever is provided which is connected through drive means to a take-up spool, part of said drive means being engageable for locking thereof by a feed-locking lever controlled by a further device driven by the measuring roller. As shown (Fig. 1), the adapter comprises a base plate 3 having an image aperture 7, a sliding shutter 6, a hinged back-cover 4, and an insert 2 having grooves 16 which co-operate with raised portions 17 for ensuring a light tight closure. Trunnions 14 are resiliently mounted in side walls 9, 10, for receiving a spool of film, the film being fed round measuring roller 11, under pressure plate 8, and round a second roller 12 to a take-up spool 13. The film winding means comprises a quick-feed lever 18 which is coupled to the take-up spool by way of gears 23-26, a ratchet wheel 28, a pin 29, and a spool-key 22 rotatably mounted on a spindle 19. A helical spring friction coupling 27 is interposed between handle 18 and gear 23 so that the handle may always be returned to the same idle position independently of its position when the film feedlock becomes effective. The indicating means for film feed and the feed-locking means are also housed in side wall 9, parts of which are shown in section in Figs. 4-6. When a roll of film is inserted into the adapter, it is wound as far as the first indication marks on the backing paper with the cover 4 open. When the cover is closed pin 47 located in grooves 16, is pushed into its lower position (Fig. 5), projection 44a of doublearmed lever 44 is removed from the recess 45 in disc 40, and pawl 43 is urged into engagement with the teeth of counter disc 39 by spring 49. When the film is wound on, disc 40, which has a slip coupling with the coaxial measuring roller 11, is made to rotate, and advances the counter disc 39 once every revolution by the engagement of pin 41 with the teeth of counter disc 39. During the initial winding of the film backing paper, a feed-locking lever 32 is held in its operative position (shown in dotted lines in Fig. 4) due to the engagement of a raised portion of a cam plate 50 rigidly fixed to the counting disc 39 with a lug 50 of the lever 32. When the film proper reaches the image aperture 7, the raised surface of cam plate 50 is removed from lug 51, projection 32a of feed-locking lever 32 is urged by spring 33 into recess 31 of disc 30 (which disc also has a slip coupling with roller 11), pawl shaped end 32b of the lever 32 is urged into locking engagement with the teeth of ratchet wheel 28, and further feed is thereby prevented. To release the feed lock for winding to the next exposure frame, lever 32 is pivoted into its inoperative position by movement of push button 35 and is held in that position by a pawl 37 which engages under spring loading with an abutment 36 on the lever 32. After one revolution of disc 30, pin 38 comes against a projecting arm of pawl 37 and the lever 32 is thereby released and later returns to its locking position when recess 31 next comes opposite the projection 32a. After the last exposure has been taken, the lever 32 is again moved to its inoperative position by the raised portion of the cam plate 50 so that the end of the backing paper can be wound on to spool 13, and short tooth 52 comes opposite disc 30 so that the counting disc 39 also becomes inoperative. Finally, when the back cover 4 is opened to remove the film, pawl 43 is urged out of engagement with the teeth of disc 39 by the now released spring 48, the counting disc returns to its zero position under loading by spring 42, and projection 44a of lever 44 is urged against disc 40 so that it re-enters recess.45 when the paper leader of the next film is wound on.