Patent GB-906812-A (GB)
Title: Photographic camera
IPC: G03B7/24
Filed: 1961-04-04
Abstract: 906,812. Photo-electric exposure control. AGFA A.G. April 4, 1961 [April 2, 1960], No. 12048/61. Class 40 (3). [Also in Group XX] In a photographic camera with semi-automatic or automatic exposure regulating means and a device for setting the same in accordance with the sensitivity of a film to be inserted in the camera, said device includes a member or members responsive to the form of a leading portion of the film or film support, which form is made characteristic of the sensitivity of the film. Six different examples of embodiment are disclosed in the Specification and each will be described, with various modifications referred to, in turn. In a first embodiment (Fig. 1), the camera comprises a supply spool 4 for film 5 and a galvanometer 20 rotatably mounted on a spindle 15 and under loading by a spring 21. On closing a hinged camera back 2 with pressure pad 3, a lever 25 is pressed inwards against loading of a compression spring 31, whereby a further lever 24 is brought into engagement under spring loading with a ratchet-wheel 23 keyed to the spindle 15. Both levers 24 and 25 are pivoted at 26, lever 24 having a slot 28 engaged by a pin 27 on the lever 25 and the two levers being coupled together by a spring 29. On advance of the film 5 in the direction of arrow a, a cut-out portion 6 of the edge of the film eventually comes up to a spring-urged exploratory lever 7, which, thereupon pivots in the direction of the arrow b. At the same time, by means of a cam 10 rotatable with the lever 7 and a lever 14 loosely pivoted about the spindle 15 and having a cam follower pin 13 at one end, a milled friction wheel 17 is brought into engagement with the film 5 whereby a drive connection is established from the film, through the wheel 17 and a pinion 18 rotatable therewith and through a pinion 19 in constant mesh with the pinion 18 to the spindle 15. After further advance of the film 5, during which advance the galvanometer is rotated in the direction opposite to the arrow c, the end 6a of the cut-out 6 comes against the lever 7 which is thereupon pivoted in the direction opposite to arrow b to break the driving connection between the film 5 and the wheel 17. Due to the engagement of lever pawl 24 with ratchet-wheel 23 the galvanometer 20 remains in its rotated position. The extent to which the galvanometer is rotated depends on the length of cut-out 6 and this is made characteristic of the speed of the film. When the back 2 of the camera is eventually opened to remove the film, the two levers 24 and 25 are pivoted in the direction opposite to arrow d under loading of spring 31, lever 24 is removed from ratchet-wheel 23 and the galvanometer 20 returns to its initial position under loading of its spring 21. In a second embodiment (Fig. 3), the camera comprises a galvanometer 88 with pointer 87 and a follow-up pointer 86 coupled through a cam 84, a pinion 85, a racked slide 83, a lever arm 82, a shaft 80, a toothed segment 81, and an axially-slidable spring-urged shaft 75 having a worm portion 79 to a cam 77 adjustable according to the exposure value setting of a shutter shown diagrammatically at 78. A spring-urged shaft 43 is coupled to the shaft 75 by way of pinions 73, 74 for providing a further setting of the follow-up pointer according to film sensitivity. On advance of film leader 41 towards take-up spool 42, an inclined edge 40 eventually comes against a pin 45 and pivots the same in the direction of arrow k. The pin 45 is carried by a member 44 which is loosely pivoted on the shaft 43 and which carries pivotally mounted thereon a pawl 47 normally in engagement with a ratchet-wheel 48 on the shaft 43. As a result of this driving connection between pin 45 and shaft 43, the two rotate together. After further advance of the leader 41, the edge 40 comes against a further pivotally mounted pin 57, whereupon, by means of a linkage system comprising members 55, 54, 52 and 50, the pawl 47 is removed from the ratchetwheel 48 and the setting for film sensitivity is completed-the extent of the rotation of shaft 43 depending on the inclination of edge 40 which is made characteristic of the sensitivity of the film. Levers 62, 63 for holding the ratchetwheel 48 and thereby also the shaft 43 in their set positions for as long as the camera back 68 is closed are provided in a manner similar to the previous embodiment (cf. corresponding levers 24, 25). In a modification of the second embodiment (Fig. 4, not shown), the pins 45 and 57, which are made shorter, are arranged to co-operate with the inclined leading edge of the film proper where it is stuck to the backing strip 41. In a third embodiment (Fig. 5), the camera comprises an adjustable mask 134 which is to be positioned in front of the photo element 135 of the exposure regulating means in accordance with the film sensitivity and a sprocketed film advancing roller 110 provided with a crown of ratchet teeth 109. Levers 122, 123 are provided for co-operation with a ratchet-wheel 121 and the camera back 128 respectively in a manner similar to the levers 24, 25 of Fig. 1. On rotation of roller 110 after insertion of the film 101 and closing of the camera back 128, by means of the crown 109, a spring-urged lever 105 is oscillated backwards and forwards about its pivot 102. A member 103 which is also pivoted at 102 and is spring coupled to the lever 105 is normally prevented from participating in the movements of lever 105 by the engagement of a part 104 thereof with the upper edge of the film 101. A number of scallops 100 are, however, provided in the film edge and when these coincide with the movement path of the part 104, the member 103 is able to oscillate with the lever 105. By means of the co-operation between a spring-urged pawl 117 mounted on the member 103 and a spring-urged ratchet crown 118, this crown is rotated tooth-by-tooth according to the number of scallops 100. As a result of the connection between crown 118 and mask 134 through spindle 120, pinion 132 and racked slide 133, the mask 134 is adjusted to a position depending on the number of scallops 100, which number is made characteristic of the sensitivity of the film 101. To facilitate rewinding of the film 101 into a cassette (not shown), a knob 136 is provided, which, on depression thereof in the direction n, breaks the connection between the roller 110 and the transmission mechanism, for example, to a rapid advancing lever and at the same time brings lugs 138, 139 of a slide 137 into engagement with members 103, 105 to render these inoperative. In a fourth embodiment (Fig. 6) the exposure regulating means comprises a photo element 166, a galvanometer 167 and an adjustable resistance 165, the adjustable contact 164 of which is carried by a pivoted toothed sector 162. The leading end 150 of the film 151 is provided with a number of perforations 152 which are engageable by a sprocket 158 carried by a pivoted spring-urged lever 154. On advance of the film 151, the sprocket 158 first slides along the leader 150 until its teeth engage in the first of the perforations 152, whereupon the sprocket is turned and, by way of a pinion 157 rigid therewith, the sector 162 is pivoted about its bearing pin 153. Immediately after sprocket 158 reaches the last of the perforations 152, an edge 150a of the film comes against a pin 177 on a spring-urged pivoted member 176, whereby this member is pivoted in the direction of arrow u and the sprocket 158 is removed from sliding engagement with the film surface as a result of the co-operation between a pin 169 on lever 154 and cam edge 170 on member 176. There is sufficient friction between contact 164 and resistance 165 to hold said contact in its set position during the above movement of the sprocket 158, which set position depends on the number of perforations 152 which in turn are made characteristic of the sensitivity of the film in use. On re-winding the film (in the direction s) into its cassette (not shown), pin 178 again slides down edge 150a, sprocket 158 is again brought into engagement with the perforations 152 and the sector 162 is thereby returned into its initial position. In a fifth embodiment (Fig. 7), the camera comprises a galvanometer 192 rotatably mounted on a spindle 191 to which are keyed a ratchet-wheel 198 and a pulley 190, an endless chord 188 connecting this pulley to a further pulley 187. A spring-urged lever 211 is provided for exploring the edge 216, 215 of the film 180. On advance of said film 180, the lever 211 rides up from the edge part 216 to the edge part 215, and, by means of a linkage comprising members 207, 205 and 203, a spring- urged pawl 200 is allowed to engage with the ratchet-wheel 198. On further advance of the film, a panel 181 secured to the face of the film comes against a pin 182 which is connected to the pulley 187 by an arm 184. By way of the pulley connection described above, the galvanometer 192 is rotated to an extent depending on the length and/or inclination of the panel surface 217 which is made characteristic of the sensitivity of the film. Upon re-winding the film, the lever 211 again explores the edge part 216, and, by way of the linkage referred to above releases the pawl 200 for return of the galvanometer and pulleys to their respective initiapositions. In a sixth embodiment (Fig. 8), drive from an electric motor 222 may be directed either through pinions 223, 225, 226 and 229 to a film advancing roller 231 or alternatively, upon pivoting of a lever 224 carrying the pinion 225, through pinions 223, 225, 232 and 233 to a galvanometer 192<SP>1</SP> which is mounted in a manner similar to the last embodiment. A lever 211<SP>1</SP> is likewise provided coupled to a pawl 200<SP>1</SP> in the same manner as before. Operation of the camera after loading with film is as follows. Upon pressing a knob 248 against its spring loading for a short time, a lever is pivoted into the position shown wherei