Mirror mechanism for a monocular reflex camera

The invention relates to a mirror mechanism for a monocular reflex camera with a laminated focal plane shutter, in which at least the opening blades of the shutter are automatically guided back into their initial positions by a spring-operated guidance member after the exposing procedure. To simplify construction of the opening blades return mechanism there is provided an arm on the shutter return mechanism which is capable of being coupled to the swivel lever for the viewfinder mirror when the opening blades move back. The swivel lever can be moved back against the action of a spring and held by a catch.

BACKGROUND TO THE INVENTION 
The invention relates to a mirror mechanism for a monocular reflex camera 
with a laminated focal plane shutter, in which at least the opening blades 
of the shutter are automatically guided back into their initial, positions 
by a spring-operated guidance member after the exposing procedure. 
STATEMENT OF PRIOR ART 
In one known mirror mechanism, there is coordinated with the swivel lever 
for the viewfinder mirror a return spring lever which is released to move 
by the closing blades which move into the closing position, and itself 
releases the guidance member for the shutter blades. This gearing 
structure is complicated, as a result of the plurality of levers acting in 
succession, gives rise not only to operational disturbances but also 
delays the initiation of the new ready-for-use position, since the shutter 
mechanism can only return to its initial position after an at least 
partial return movement of the viewfinder mirror. 
OBJECT OF THE INVENTION 
With the object of operationally secure accceleration of the return of the 
shutter blades and the mirror mechanism to the new ready-for-use position, 
the problem of the invention is to produce a simplified construction of 
the return guidance mechanism. 
SUMMARY OF THE INVENTION 
According to the invention there is provided a lamellar focal-plane shutter 
for monocular mirror reflex cameras having a swivelling viewfinder mirror 
movable between a first viewing position in the optical path of the camera 
and a second position clear of said path for exposure and shutter blades 
which return automatically to their starting positions after each exposure 
operation, comprising a drive member for returning said shutter blades and 
movable between a rest position and a tensioned position, a first spring 
attached to said rod for tensioning upon cocking of the camera, a first 
detent lever for holding said drive member in a tensioned position, means 
on said shutter for actuating said detent lever when the shutter arrives 
at its closed positioned, a pivoted lever for driving said reflex mirror 
from its first position to its second position, a second spring connected 
to said pivoted lever to urge the reflex mirror towards its second 
position, a second detent lever for holding said pivoted lever in a cocked 
position against the action of said second spring, and an arm disposed on 
said drive member and engageable with said pivoted lever to drive the 
latter during a return movement of the drive member to its rest position, 
whereby on release of said drive member the latter moves under the tension 
of said first spring to drive simultaneously said shutter blades into 
their starting positions and to drive said pivoted lever against the 
action of said second spring permitting the reflex mirror to return to its 
first position. Apart from the simplified constructional assembly, there 
is provided through this technological measure the advantage that the 
guidance of the mirror and the guidance of the shutter blades cannot take 
place in time order, but the guidance of the shutter blades can take place 
during the guidance of the viewfinder mirror. By virtue of one 
advantageous construction, the viewfinder mirror is loaded with a return 
spring which attempts to keep the viewfinder mirror in non-positive 
communication with the swivel lever. By virtue of a further advantageous 
construction, a simultaneous stop actuation is achieved, since the swivel 
lever engages with a driving pin in the cavity of an actuating rocker arm 
for the objective stop.

DESCRIPTION OF PREFERRED EMBODIMENTS 
The viewfinder aperture 23, and below it the picture window 18, is provided 
in the camera housing 1 (see FIG. 1). The picture window 18 can be closed 
by the opening blades 24 (a, b and c) and the closing blades 26 (a, b, and 
c). The opening blades 24 can be moved by the opening lever 29 and its 
shear-lever 21. The opening spring 30 is fastened to the opening lever 29 
on the one hand, and to the clamping plate 31 on the other; 
correspondingly, the closing spring 33 is fastened by one end to the 
closing lever 32, and by the other end to the clamping plate 34. The 
opening lever 29 possesses a catch 39, which is located in the swivelling 
path of the stop 37 of the clamping plate 31. The opening lever 29 can be 
secured counter to the opening spring 30 by the opening catch 41 and the 
closing lever 32 can be secured counter to the closing spring 33 by the 
closing catch 42. The two clamping plates 31 and 34 are connected together 
by the re-guidance member 35. The re-guidance member 35 can be moved by 
the re-guidance spring 36 and can be secured by the stop lever 28 counter 
to the re-guidance spring 36. The re-guidance member 35 has a re-guidance 
arm 27 for the viewfinder mirror 2. 
The viewfinder mirror 2 is rotatably mounted about the shaft 3 (see FIG. 2) 
in the camera housing 1. The recuperating spring 4 keeps the viewfinder 
mirror 2 in engagement with the driving pin 5 of the swivel lever 6. The 
swivel lever 6 projects with the driving pin 7 into the recess 8 of the 
actuating arm 9. The adjusting push rod 14, which is spring-loaded in the 
direction of the arrow, of a preselecting stop located in the objective 
housing 15 which can be placed against the camera housing 1, butts against 
the actuating tab 13 of the actuating rocker arm 9. 
On the locking pin 16 of the swivel lever 6, the latter is retained counter 
to its swivel spring by the disengaging catch 17. The disengaging arm 10 
for the opening catch 41 of the shutter is located on the swivel lever 6. 
The mode of operation of the arrangement is as follows: 
When the shutter is tensioned, the parts are in the position as per FIG. 1 
or FIG. 1a and FIG. 2. By actuating the disengaging catch 17, the driving 
lever 6 is released to run its course (see FIG. 3), and because of the 
driving spring 19, is rotated in clockwise direction about its bearing pin 
11. During this movement, the viewfinder mirror 2 is rotated via the 
driving pin 5 counter to the recuperating spring 4 into the horizontal 
exposure position, and the actuating rocker arm 9 is rotated via the 
driving pin 7 in counterclockwise direction into the position as per FIG. 
3. Here, the objective-sided adjusting push rod 14 is pressed in counter 
to the direction of the arrow, so that the objective stop closes at the 
preselected value. 
Thereafter, the driving lever 6 strikes the opening catch 41 (see FIG. 4) 
and swivels the latter out of engagement with the opening lever 29 in 
clockwise direction. Because of the opening spring 30, the opening lever 
29 and the shear-lever 20 are made to move the opening blades 24a, 24b and 
24c; the opening blades 24 (a, b and c) then adopt the position which can 
also be seen in FIG. 4a, so that the picture window 18 is opened for 
exposing a film. The catch 39 of the opening lever 29 comes into contact 
with the stop 37 of the clamping plate 31. 
The closing catch 42 is swivelled in known manner in clockwise direction 
and brought out of engagement with the closing lever 32 by a mechanical or 
electronic device for producing different exposure times. Because of the 
closing spring 33, the closing lever 32 and the shear-lever 21 are made to 
move the closing blades 26a, 26b and 26c; the closing blades 26 (a, b and 
c) then adopt the position shown in FIGS. 5 and 5a, in which the picture 
window 18 is closed again. The catch 40 of the closing lever 32 comes into 
contact with the stop 38 of the clamping plate 34. 
When its course is ended, the closing lever 32 with its end 25 strikes the 
catch lever 28 and swivels the latter in clockwise direction out of 
engagement with the re-guidance member 35. The re-guidance member 35 is 
moved downwardly by the re-guidance spring 36, so that the two clamping 
plates 31 and 34 are rotated in clockwise direction. Here, the clamping 
plate 31 moves the opening layer 29 by means of the stop 37 via the catch 
39, and the clamping plate 34 moves the closing lever 32 by means of the 
stop 38 via the catch 40 in clockwise direction, so that the opening 
blades 24 and the closing blades 26 are simultaneously moved into their 
initial positions. No release of the picture window 18 occurs during this 
re-guidance of the opening blades 24 and the closing blades 26, so that 
the film situated behind it is not exposed unintentionally. Through the 
re-guidance member 35, the opening lever 29 and the closing lever 32 are 
moved outwardly by the paths a or b through the positions which are 
defined by the opening catch 41 or the closing catch 42. 
During the re-guidance movement of the re-guidance member 35, its 
re-guidance arm 27 seizes the edge 12 of the swivel lever 6, whereby the 
swivel lever 6 is driven counter to the swivel spring 19 into its initial 
position which is retained by the disengaging catch 17. The recuperating 
spring 4 rotates the viewfinder mirror 2 again into the viewfinder 
position, following the catch pin 5. Simultaneously, the actuating rocker 
arm 9 is rotated in clockwise direction, whereby the adjusting push rod 14 
can follow the actuating tab 13, so that the objective stop fully opens 
again. 
In the new tensioning procedure, the re-guidance member 35 is moved counter 
to the re-guidance spring 36 into the position as per FIG. 1, where it is 
retained by the catch lever 28. In this tensioning movement, the clamping 
plates 31 and 34 are rotated in counterclockwise direction. Because the 
opening lever 29 is stopped by the opening catch 41 and the closing lever 
32 is stopped by the closing catch 42, the opening spring 30 and the 
closing spring 33 are tensioned.