GB2150698A - Shutter diaphragm - Google Patents

Abstract

In a control device for a shutter diaphragm, the shutter-opening action of a shutter-operating member 11 is under the action of a spring 17 connected to a closure member 18 and is terminated abruptly by the locking of a detent 27 connected to member 11 with teeth 36 on member 18 and simultaneous release of member 18 to return member 11 to its original position under the action of a spring 2. On shutter release, catch 29 pivots clockwise to release tensioning member 40/42 which moves upwards (to position shown) under action of spring 38 to start the shutter-timing process by opening switch 47 and the exposure process by releasing member 11 from detent 22. Member 11 moves downwards (to position shown) to operate shutter- opening segment lever 8. On completion of the shutter-timing process, electromagnet 45 is released and signal lever 24 is pivoted clockwise, allowing detent 27 to engage teeth 36 under action of spring 28, preventing further opening movement of member 11, and releasing member 18, which moves upwards (from position shown) together with member 11, to effect shutter closing. Recocking is effected by pushing member 37 downwards, member 18 thereby being also moved downwards and springs 17, 21 and 38 tensioned. <IMAGE>

Description

SPECIFICATION Control device for diaphragm shutter The invention relates to a control device for a photographicdiaphragm shutter, the shutter blades of which can be moved by an opening member out of the closed position into an open position and by a spring-driven closure member out of the open position into the closed position, the opening member being capable of being pre-tensioned against the closure member, a closure signal releasing the closure member for movement.

In the case of known diaphragm shutters of this type (DAS 190 1850, DOS 2511894), during triggered movement of the opening member the shutter opening is increasingly enlarged by the shutter blades and the closure signal is given when the film has been adequately exposed. In spite of this, the opening process persists long enough that, released for movement by the closure signal and running against the opening member, the closure member meets the opening member and moves the opening member back with a view to making the shutter aperture smaller. The time lapse between the closure signal and the actual closure process which does not start until after further opening is not accurately determinable and, particularly in the case of considerable object brightness, is subject to considerable fluctuation, for example by short exposure times characterised by small diaphragm apertures.

The object of the invention is to improve the open attitude of the said type of diaphragm shutters in keeping with the available brightness.

The object of the invention is to provide a control device which prevents an undesirable further opening or maintenance of an open state of the shutter plates after the closure signal has been given. According to the invention, this is achieved in that a locking device is provided which can be likewise actuated by the closure signal and which abruptly interrupts the opening movement of the opening member. Expeditently, there is between the opening member and the closure member a rigid mechanical connection which can be triggered by the closure signal and cancelled upon return of the opening member to its starting position.In accordance with a preferred embodiment, where the closure signal is concerned, a brief rigid connection is established between the opening member and the closure member in that a row of locking teeth are provided on the opening member parallel with the direction of movement thereof, while on the closure member there is rotatably mounted a detent which is spring loaded in the locking direction and which can be maintained disengaged from the locking teeth on the one hand by a signal lever and on the other by a pivot lever which is rotatably mounted on the opening member and which, in the starting position of the opening member, can be moved towards a fixed stop.In accordance with another advantageous embodiment, where the closure signal is concerned, the opening movement is abruptly interrupted in that a row of locking teeth are provided on the opening member, to extend parallel with the direction of movement of the opening member, while in the shutter housing there is rigidly mounted a detent which is rotatable under spring bias in the locking direction, being held disengaged from the locking teeth by a signal lever. It is convenient if the signal lever carries the armature for the electromagnet, which can be energised or de-energised by an exposure measuring circuit.Preferably, the signal lever has a restoring spring which pivots the armature against the electromagnet and which can be driven in the restoring direction by the restoring cam of a tensioning member in the tensioning position thereof, a position which can be secured by the shutter release.

The invention is explained hereinafter with reference to embodiments which are described and illustrated in the accompanying drawings, in which: Fig. 1 shows a first control device in the cocked position: Fig. 2 shows the control device when the closure signal is received; Fig. 3 shows a further control device in the cocked position and Fig. 4 shows the further control device when the closure signal is received.

The shutter segments 1 and 2 are rotatably mounted on the studs 3 and 4 on a baseplate which is not especially illustrated and which corresponds substantially to the paper plane.

Protruding through the slots 5 and 6 in the shutter segments 1 and 2 is the drive pin 7 of the segment lever 8 which is likewise mounted to rotate about the stud 3. The pin 9 of the segment lever 8 protrudes through the slot 10 of the opening member 11, through the guide slots 1 2 and 1 3 in which protrude the guide pins 14 and 14 which are mounted on the baseplate. Fixed on the lug 1 6 is one end of the opening spring 17, the other end of which is connected to the closure member 1 8. Against the opening spring 17, the opening member 11 is prevented from moving unintentionally by the detent 22.The closure member 1 8 is likewise provided with guide slots 1 9 and 20 through which protrude guide pins 14 and 1 5. The bent-over lug 35 projects into the path of movement of the closure edge 23 of the closure member 1 8.

Fixed on the closure member 1 8 is the closure spring 21 which is anchored on the baseplate.

Against the closure spring 21, the closure member 1 8 is maintained by the locking lever 24 which is mounted to rotate about the fixed stud 25.

Rotatably mounted on the pin 26 of the closure member 1 8 is the detent 27 which is biased in a clockwise direction by a spring 28. Against the spring 28, the detent 27 is held on the one hand by the signal lever 24 and on the other by the pivot lever 30 which grips the lug 31 of the detent 27 and which is rotatably mounted on the pin 32 of the opening member 11; the fixed abutment 33, in the starting position of the opening member 11, presses the pivot lever 30 against the spring 34 towards the lug 31 of the detent 27. Parallel with the guide slots 1 2 and 13, the opening member 11 has a row of locking teeth 36 into which the detent 27 can engage.

Likewise on the guide pins 14 and 15, tensioning member 37 is mounted for displacement by guide slots, the rigidly anchored spring 38 being fixed to the tensioning member 37 which has a tensioning lug 39 which can cooperate with the projection 50 on the closure member 1 8. The tensioning member 37 is held against the spring 38 by the release catch 29. Furthermore, the tensioning member 37 is in a position to close the switch 41 by an arm 40 and to grip the detent 22 by the bent-over arm 42. The timing circuit 43 provided serves to energise or shut down the electromagnet 44, the armature 45 of which is connected to the signal lever 24. The armature can be applied against the spring 49 on the electromagnet 44 by means of the restoring cam 47 of the tensioning member 37, via the restoring spring 46 provided on the signal lever 24.

This arrangement operates in the following way: If, when the shutter mechanism is cocked (see Fig. 1), the release catch 29 is pivoted in a clockwise direction and so disengaged from the tensioning member 37, then by reason of the spring 38, the tensioning member 37 moves rightwardly. Firstly, this closes the switch 41, activating the electromagnet 44 and attracting the armature 45. During the further movement of the tensioning member 37, the restoring cam 47 moves away from the restoring spring 46 and in turn releases the signal lever 24. Subsequently, the tensioning lug 39 opens the starter switch 47 for the electronic time forming process and, with the arm 42, pivots the detent 22 anticlockwise and disengages it from the opening member 11, so that the exposure process is initiated.By virtue of the opening member 11 moving leftwardly under the action of the opening spring 17, the pin 9, via the slot 10; moves the segment lever 8 anti-clockwise.

When this happens the drive pin 7, through the slots 5 and 6, entrains the shutter segments 1 and 2 which increasingly open up the exposure aperture 48. Upon commencement of the necessarily slightly braked movement of the opening member 11, the pivot lever 30 moves away from the fixed stop 33, so that the spring 34 can rotate the pivot lever 33 anti-clockwise and away from the lug 31 of the detent 27. Consequently, during f urther movement of the opening member 11, the detent 27 is only held disengaged from the locking piece by the signal lever 24.

As soon as the electromagnet 44 is switched off by the closure signal from the timing circuit 43, the spring 49 can rotate the signal lever 24 in a clockwise direction and disengage it from the closure member 18 (see Fig. 2). Simultaneously, the signal lever 24 releases the detent 27, the locking spring 28 of which causes the detent 27 to engage one of the locking teeth 36. Thus, not only is movement of the opening member 11 interrupted but, together with the closure member 18, moving as a result of the closure spring 21, the opening member 11 is immediately moved back rightwardly. This reversal of movement is transmitted via the segment lever 8 directly to the shutter segments 1 and 2 which start to close the exposure aperture 48 again.When the closure position of the shutter segments 1 and 2 is reached, the opening member 11 also reaches its starting position, the pivot lever 30 striking the abutment 33 by which it is moved in a clockwise direction against the spring 34. During this movement, the pivot lever 30 grips the lugs 31 and disengages the detent 27 from the locking teeth 36, so that the closure member 1 8 can without hindrance move into its relaxed extreme position.

Movement of the control device into the cocked position takes place by pushing the tensioning member 37 leftwardly, the tensioning lug 39 entraining the closure member 18 through the projection 50. During this cocking or tensioning movement, the spring 38 of the tensioning member 37 and the closure spring 21 of the closure member 1 8 as well as the opening spring 1 7 of the opening member 11 which is held by the detent 22 are cocked.

In accordance with a further simplified embodiment (see Fig. 3), the detent 51 is rigidly mounted but is rotatable concentrically of the signal lever 24. The rest of the construction is substantially unchanged. Once a flash process is triggered, then in accordance with this arrangement when the closure signal is given by the timing circuit 43, the signal lever 24 is pivoted in a clockwise direction by the spring 49 (see Fig. 4). When this happens, the closure member 18 is free to move and the detent 51 to engage the locking teeth 36.

Consequently, the opening movement of the opening member 11 is interrupted. As soon as the closure edge 23 of the closure member 18 has reached the lug 35 of the opening member 11, the closure movement of the shutter segments 1 and 2 commences,in that the closure member 1 8 moves the opening member 11 back into its starting position.

When this happens, the locking teeth 36 slide past and under the detent 51.

The invention is not confined to the embodiments which have been illustrated. In particular, the opening and closure members provided may be also rotatable or constructed as rings. What is always essential is that the opening movement of the shutter segments be interrupted immediately upon emission of the stop signal.

Claims (7)

1. A control device for a photographic diaphragm shutter, the shutter plates of which can be moved by an opening member out of the closed position into an open position and by a spring-driven closure member out of the open position into the closed position, the opening member being capable of being pretensioned against the closure member, a closure signal releasing the closure member for movement, characterised in that a locking device (27, 36; 51, 36) is provided which can be likewise actuated by the closure signal and which abruptly interrupts the opening movement of the opening member (11).

2. A control device according to para. 1, characterised in that there is between the opening member (11) and the closure member (18) a rigid mechanical connection which can be triggered by the closure signal and cancelled upon return of the opening member (11) to its starting position.

3. A control device according to para. 2, characterised in that a brief rigid connection is established between the opening member (11) and the closure member (18) in that a row of locking teeth (36) are provided on the opening member (11) parallel with the direction of movement thereof, while on the closure member (18) there is rotatably mounted a detent (27) which is spring loaded in the locking direction and which can be maintained disengaged from the locking teeth (36) on the one hand by a signal lever (24) and on the other by a pivot lever (30) which is rotatably mounted on the opening member (11) and which, in the starting position of the opening member (11), can be moved towards a fixed stop (33).

4. A control device according to para. 1, characterised in that a row of locking teeth (36) is provided on the opening member (11) and extends parallel with the direction of movement of the opening member (11), and in that in the shutter housing there is rigidly mounted a detent (51) which is rotatable under spring bias in the locking direction and can be maintained disengaged from the locking teeth (36) by a signal lever (24).

5. A control device according to paras. 1 or 2, characterised in that the signal lever (24) carries the armature (45) for an electromagnet (44) which can be energised or de-energised by an exposure measuring circuit (43).

6. A control device according to para. 5, characterised in that the signal lever (24) has a restoring spring (46) which pivots the armature (45) against the electromagnet (44) which can be driven in the restoring direction by the restoring cam (47) of a tensioning member (37) in its cocked position, which can be secured by the shutter release (29).

7. A control device as claimed in Claim 1 substantially as described with reference to Figures 1 and 2 or Figure 3 and 4 of the accompanying drawings.