US3559547A

US3559547A - Photographic shutter with reciprocating shutter blade driving member and electronic timing device

Info

Publication number: US3559547A
Application number: US772571A
Authority: US
Inventors: Waldemar T Rentschler
Original assignee: Prontor Werk Alfred Gauthier GmbH
Current assignee: Hittech Prontor GmbH
Priority date: 1968-11-01
Filing date: 1968-11-01
Publication date: 1971-02-02
Anticipated expiration: 1988-02-02

Abstract

A photographic shutter having a driving member which when moved from a normal position opens and then closes the shutter by means of a reciprocating actuating member, an electronic timing device controls an armature lever biased by a return spring with the aid of a photoelectric resistor in dependence upon the ambient light. The armature lever cooperates with a pawl blocking the actuating member in the open position of the blades for the duration of the timing. A switch is connected in the circuit of the electronic timing device and closes a contact when the cocking mechanism of the camera is actuated, the contact short circuiting the photoelectric resistor.

Description

United States Patent 72] Inventor Waldemar T. Rentschler Calmbach, Germany [2]] Appl. No. 772,571

[22] Filed Nov. 1, 1968 [45] Patented Feb. 2,1971

[73] Assignee Prontor-Werk G.m.b.H.

Calmbach, Germany [54] PHOTOGRAPHIC SHUTTER WITH RECIPROCATING SHUTTER BLADE DRIVING MEMBER AND ELECTRONIC TIMING DEVICE 3 Claims, 4 Drawing Figs.

[52] U.S.Cl 95/10 [51] G03b 7/08 [50] Field ofSearch ..95/1OC, 31, 53

[56] References Cited UNITED STATES PATENTS 3,326,103 6/1970 Topaz 95/10(C) 3,367,251 2/1968 Furuta 3,422,738 1/1969 Morietal.

95/C1X 95/10(C) ABSTRACT: A photographic shutter having a driving member which when moved from a normal position opens and then closes the shutter by means of a reciprocating actuating member, an electronic timing device controls an armature lever biased by a return spring with the aid of a photoelectric resistor in dependence upon the ambient light. The armature lever cooperates with a pawl blocking the actuating member in the open position of the blades for the duration of the timing. A switch is connected in the circuit of the electronic timing device and closes a contact when the cocking mechanism of the camera is actuated, the contact short circuiting the photoelectric resistor.

PATENTEU F512 1971' SHEET 2 OF 2 IN VE N TOR Waldemar 7. RenIsch/er BY March Gillelie8 WyaH A TTOR NE Y5 PHOTOGRAPHIC SHUTTER WITH RECIPROCATING SHU'I'I'ER BLADE DRIVING MEMBER AND ELECTRONIC TIMING DEVICE The invention concerns a photographic shutter the driving member of which in moving from a normal position, moves the blades first into an open and then into a closed position by means of a reciprocating actuating part, an electronic timing device being provided which includes a photoelectric resistor and controls an armature lever biased by the action of a return spring in dependence upon ambient light conditions. The driving member cooperates with a stop lever locking the actuating part of the blades for the duration of the timing operation.

When taking photographs with electronic timing depending on ambient light, very long exposure times may .result with poor light, so that the photographer, concluding that exposure has terminated, may attempt to recock the shutter. Since the blade ring is locked in the open position of the blades for the duration of timing, the return of the driving mechanism to the cocked position is not possible because of the engagement of the blade ring and the member driving it, until the ring returns to normal at the end of the exposure. If the photographer is ignorant of the lockup mentioned above and exerts force, then parts of the blocking gear train may be damaged or broken.

In order to break in to the automatic exposure action already begun, i.e. to terminate the timing procedure indepen dently of the switching device, a switch connected parallel to the photoelectric resistor and actuated by means of a manually actuated button has already been proposed. This switch is suitable for terminating the timing procedure but does not prevent damage to the gear train of the said cocking mechanism if the photographer ignores the switching state of the electronic timing device and tries to cock the shutter.

It is an object of the present invention to actuate the switch terminating the timing of an electronic shutter in dependence upon certain constantly repeated operational manipulations. For this purpose the invention provides a switch in the circuit of the electronic timing device, actuated independently of the cocking mechanism of the camera, which closes a short circuit across the photoelectric resistor. In this way the electronic timing action may be prematurely terminated and hence the unlocking of the shutter drive by an operation to be effected by the photographer at the end of an exposure is canceled.

Preferably the switch is located in the path of the camera cocking lever and is adapted to be actuated directly thereby. In one form of the invention the switch has a displaceable contact spring supported against the cocking lever and following the operating movement of this lever, the spring cooperating with a further fixed contact spring.

An embodiment of the invention is illustrated in the accompanying drawings and is described in detail below. In the drawings:

FIG. 1 shows a shutter with an electronic timing device in the cocked position; the switch short circuiting the photoelectric resistor is opened by the camera cocking lever located in the normal position;

FIG. 2 is a view of part of the shutter shown in FIG. 1, the blade driving mechanism of which is blocked in the open position of the blades;

FIG. 3 shows the shutter part of FIG. 2 with the blade driving mechanism in a movement phase during the closing process; and

FIG. 4 is a fragmentary section on the line IV-IV of FIG. 2.

In a housing 1 of a photographic shutter a base plate 2 with a tubular socket 2a is arranged, to mount the shutter-driving device. The latter consists of a driving disc 5 mounted on a cocking shaft 4, a driving spring 6 acting thereon and a driving member or pawl 7 connected to the driving disc, the free end of paw], which is provided with a lug 8a, cooperating with an actuating part 8 of the blades 9 formed as a ring so that the action of the driving ring always occurs from a normal position in a clockwise direction of the blade ring, the blades executing a reciprocating movement. A two-armed stop lever 10 is used to lock the driving disc 5 in the cocked position as shown in FIG. 1. a further two-armed release lever 11 indicated in this view engaging with one lever arm thereof. This lever 11 is actuated by means of a camera release member 12 shown only in part in FIG. 1, via further intermediate members which are shown by a chain-dotted line.

To retain the blades 9 in the open position for the duration of the exposure time determined by an electronic timing device described below, the blade ring 8 has a further lug 8b passing through a slot, (not shown) in the base plate 2, in front of which, as shown in FIGS. 2 to 4, a spring-loaded stop catch 14 assumes a position with its lug 14a in the open position of the blades 9. This catch mounted on a spigot 15, carries a pin 14b, and is urged by a spring 16 into the stop position. To disengage the catch 14 from the stop position at the end of the timing procedure an armature lever 18 mounted on a pin 17 is provided, on which there is a lifting arm 18a cooperating with the pin 14b of the catch. On the free end of the lever 18 there is an armature 20 acted upon by an electromagnet 21 connected in the circuit of the electronic timing device. The armature lever 18 during the cocking procedure is pressed against the electromagnet 21. For this purpose there is a lever 24 mounted on a pin 23 which, when the driving disc 5 is transferred into the cocking position, is rotated in a clockwise direction by means of a pin 5a of this disc and by means of a pin 24a causes the armature lever to abut with its free end against the electromagnet 21, against the action of a return spring 25.

In the embodiment of an electronic shutter shown in the drawings, the driving disc 5 is moved into the cocking position in known manner by means of a camera cocking lever 27 arranged on the camera, which lever also acts on a film transfer device. The engagement between cocking lever 27 and the cocking shaft 4 carrying the driving disc 5 is indicated in the drawing merely by the chain-dotted line 28. A spring 29 retains the cocking lever 27 in abutment against a fixed pin 30 which determines the normal position of this lever.

The above-mentioned electronic timing device is a known transistorized relaxation circuit and therefore is not shown in further detail. This circuit includes an electronic switch 32, which cooperates with a RC circuit including a photoelectric resistor R and capacitor C which determines the duration of the exposure time; the circuit energizes the electromagnet 21. A contact switch S which is closed when the release lever 12 is actuated serves to connect the electronic time control circuit to a battery B. A further contact switch S formed as a changeover switch is provided to short circuit the capacitor C in the contact position (FIG. 1) corresponding to the closed position of the shutter. The beginning of the opening movement of the blade ring 8 moves this switch to initiate the charging of the capacitor and establishes a parallel connection to the switch 8,. To actuate the changeover switch S a pin is provided on the blade ring 8, which pin, in the normal position of the blade ring, retains the changeover switch in the contact position shown. When the blade ring 8 commences to move, the contact blade of the changeover switch 8, follows pin 8c and changes over into the other contact position, not shown.

As already indicated, the stop lever 14 is moved out of its stop position at the end of the timing procedure by the armature lever 18. When taking a photograph with a relatively long exposure time, the photographer may attempt to recock the shutter although the action of the electronic timing device-has not yet been completed. This is prevented by the pawl 14 which is still in the stop position, because during a cocking movement from the open position shown in FIG. 2 the driving disc 5 tries to drive the blade ring 8 in an anticlockwise direction. This rotary movement of the blade ring 8 is prevented by the pawl 14 which is still located in the stop position, so that if force is exerted the mechanism could be damaged or broken. To prevent damage to the mechanical gear train, the aforesaid shutter arrangement has an additional operating device provided which during a premature cocking procedure overrides and terminates the exposure timing and hence cancels the blocking of the shutter drive. This device consists of a further switch S in the circuit of the electronic timing device, by means of which when the camera is cocked, a short circuit is produced across the photoelectric resistor R. To actuate thisswitch S the camera cocking lever 27 is used, the pin 27a of which cooperates with a contact spring 33 of the switch, which consists of this spring and a further contact spring 34. The arrangement is such that in the normal position of the camera cocking lever the contact spring 33, as shown in FIG. 1, is supported against the pin 27a, causing the switch S to open. When the cocking lever 27 of the camera is moved in the direction indicated by the arrow, the contact spring 33, following the pin 27a, abuts against the contact spring 34 thus short circuiting the photoelectric resistor R.

When taking a photograph the switch S is open and there fore does not affect the electronic timing device. When the release 12 is depressed, switch S is closed, and the driving disc simultaneously released by rotation of the stop lever in a clockwise direction. The disc 5 now moves under the influence of the spring 6, the blade ring 8 being driven into the open position as shown in FIG. 2, in which the pawl 14 with its lug 14a assumes a position in front of the lug 8b of the blade ring, so that the driving mechanism is blocked. Closure of the switch S causes the electromagnet 21 and the electronic timing device to be connected to the battery B. The electromagnet 21 retains the armature lever 18 in the position shown in FIG. 1 after the driving disc 5 has started. The switch S in the first phase of movement of the blade ring 8 changes over into its other contact position, causing the capacitor C to be charged and hence the timing in the electronic control circuit to begin. The time taken to charge the capacitor C to the operating value of the electronic switch 32 is dependent upon the resistance value of the photoelectric resistor R, which itself is dependent upon the ambient light. When finally the capacitor C has reached this operating value, then the electronic switch 32 reverses and the magnetic field of the electromagnet 21 collapses. The return spring now swings the armature lever 18 in a clockwise direction, causing the lifting arm 18a to move the pawl 14 out of the stop position, so as to allow the shutter to close again (FIG. 3). If subsequently the shutter is again cocked by movement of the camera cocking lever 27 in the direction of the arrow, then the switch s closcs briefly but this does not affect the electronic timing device, since the timing procedure has ended.

Should it occur that the photographer attempts to recock the shutter before the exposure, based on prevailing low light conditions, has not ended, as a consequence of which the blade ring 8 is still blocked, then the action of the electronic timing device is prematurely terminated. This is effected by closing the switch S with the first movement stroke of the camera cocking lever 27 and applying a short circuit to the photoelectric resistor R, which immediately alters the state of charge of the capacitor C. Consequently the electronic timing device operates immediately, which in turn results in the cancellation of the blocking of the shutter drive and initiates a closing movement of the shutter blade system.

Iclaim:

1. A photographic shutter including a driving member which when moved from a normal position opens and then closes the shutter by means of a reciprocating actuating member, an electronic timing device controlling an armature lever biased by a return spring with the aid of a photoelectric resistor in dependence upon the ambient light, said armature lever cooperating with a pawl blocking the actuating member in the open position of the blades for the duration of the timing, wherein a switch connected in the circuit of the electronic timing device closes a contact when the cocking mechanism of the camera is actuated, said contact short circuiting the photoelectric resistor.

2. A photographic shutter according to claim 1, wherein the switch is located in the path of the cocking lever of the camera and is actuated directlK thereby.

3. A photographic s utter according to claim 2, wherein the switch has a displaceable contact spring supported against the cocking lever and following the movement of this lever, which spring cooperates with a further fixed contact spring.

Claims

2. A photographic shutter according to claim 1, wherein the switch is located in the path of the cocking lever of the camera and is actuated directly thereby.

3. A photographic shutter according to claim 2, wherein the switch has a displaceable contact spring supported against the cocking lever and following the movement of this lever, which spring cooperates with a further fixed contact spring.