Exposure rate controlling mechanism for camera

An exposure rate controlling mechanism for a camera comprising an iron member controlled to move to more than three attracted/departed positions by an electromagnet and a mechanism for controlling the exposure rate corresponding to the position to which the iron member moves. The mechanism for controlling the exposure rate comprises an exposure rate controlling member which is moved to a position corresponding to the position to which the iron member moves and an exposure rate determining member which is controlled to move by an amount corresponding to the amount of displacement of the exposure rate controlling member.

DESCRIPTION 
1. Technical Field 
The present invention relates to an exposure rate controlling mechanism for 
a camera with a release type electromagnet device. 
2. Background Art 
There has conventionally been suggested an exposure rate controlling 
mechanism for a camera with a release type electromagnet device. In such a 
conventional mechanism, the release type electromagnet device used therein 
includes a very complicated coupling structure of an iron member and an 
exposure rate determining member which is controlled to move by an amount 
determined corresponding to an amount of displacement of the iron member. 
The present invention has been suggested to remove such a defect inherent 
in the conventional exposure rate controlling mechanism for a camera. 
DISCLOSURE OF INVENTION 
Therefore, it is the object of the present invention to provide an exposure 
rate controlling mechanism for a camera in which an iron member 
constituting an exposure rate controlling means and imparted with a 
repulsive nature against an electromagnet and an exposure rate determining 
member which is controlled to move by an amount determined corresponding 
to an amount of displacement of the iron member are coupled to each other 
organically so that the exposure rate determining member functions to hold 
pressingly the iron member against the electromagnet.

BEST MODE FOR CARRYING OUT THE INVENTION 
The present invention will now be described by way of an embodiment in 
which it is applied as a controlling means of a diaphragm opening degree 
of a camera with reference to the accompanying drawings. 
In the drawings, the numeral 1 denotes an electromagnet in which two pairs 
of magnetic poles 1a and 1b are wound respectively with two pairs of coils 
1c and 1d. 
The numeral 2 denotes an iron lever secured to a shaft 3 pivotably and 
restrained by a spring 4 to rotate in the counterclockwise direction. The 
iron lever 2 has a bent part 2a and a pair of shafts 2b and 2c planted 
thereon. The numeral 5 denotes a first iron member pivotably secured to 
the shaft 2b of the iron lever 2 and forming a counterpart to the magnetic 
pole 1a of the electromagnet 1. The numeral 6 denotes a second iron member 
having an elongated groove 6a with which the shaft 2c of the iron lever 2 
engages in an idling condition and forming a counterpart to the magnetic 
pole 1b of the electromagnet 1. 
The numeral 7 designates an iron cooperating lever secured to a shaft 8 
pivotably and restrained by a weak spring 9 to rotate in the clockwise 
direction. The iron cooperating lever 7 has a projection 7a through which 
the lever 7 is brought into contact with the bent part 2a of the iron 
lever 2. The lever 7 also includes an elongated groove 7b which will be 
described later. The numeral 10 designates a diaphragm control lever which 
is engaged in an idling condition with the large diameter part 8a of the 
shaft 8 through an elongated groove 10a provided therein. The diaphragm 
control lever 10 has a bent part 10b and a pin 10c planted thereon (this 
pin 10c extends through the front and back surfaces of the lever 10). The 
levers 7 and 10 are engaged with each other with the pin 10c of the lever 
10 inserted into the elongated groove 7b of the lever 7. A spring 11 is 
provided between these two levers 7 and 10 so as to pull the diaphragm 
control lever 10 in the leftward direction in FIG. 1. 
The numeral 12 designates a diaphragm operating lever secured pivotably to 
a shaft 13 and restrained by a spring 14 to rotate in the counterclockwise 
direction. This lever 12 has a shaft 12a planted thereon. The numeral 15 
denotes a diaphragm rate determining lever pivotably secured to the shaft 
12a of the diaphragm operating lever 12. This diaphragm rate determining 
lever 15 includes an elongated groove 15a into which the shaft 8 is 
inserted in an idling condition, three recessed parts 15b, 15c and 15d 
engageable with the pin 10c of the diaphragm control lever 10, a stepped 
part 15e and three bent parts 15f, 15g and 15h. This lever 15 is also 
planted with a shaft 15i. 
The numeral 16 denotes a holding lever which is pivotably secured to the 
shaft 15i of the diaphragm rate determining lever 15 and restrained by a 
spring 17 having a force stronger than that of the spring 4 to rotate in 
the clockwise direction until the rotation is prevented by the stepped 
part 15e of the lever 15. This holding lever 16 has a bent part 16a which 
pushes the bent part 10b of the diaphragm control lever 10. The numeral 18 
denotes a first engaging lever which is pivotably secured to a shaft 19 
and restrained by a spring 20 to rotate in the clockwise direction. This 
lever 18 is formed with an arm 18a through which the lever 18 is engaged 
with the bent part 15g of the diaphragm rate determining lever 15. The 
numeral 21 denotes an operating arm of a diaphragm operating ring not 
shown which is arranged so as to be rotated in the counterclockwise 
direction around an optical axis 0 according to the movement of the bent 
part 15f of the diaphragm rate determining lever 15 on the release 
operation. The operating arm 21 is then rotated in the clockwise direction 
by said lever 15 when the latter is set. 
The numeral 22 denotes a setting plate which is arranged movably in 
parallel to the diaphragm rate determining lever 15 and restrained by a 
spring 23 to move in the leftward direction in the drawing. This setting 
plate 22 has an arm 22a which pushes the bent part 15h of the lever 15 
when the setting plate 22 is moved leftwardly. The setting plate 22 also 
has a projection 22b, which will be described later. 
The numeral 24 denotes a second engaging lever pivotably secured to a shaft 
25 and restrained by a spring 26 to rotate in the counterclockwise 
direction. This second engaging lever 24 engages with the setting plate 22 
by means of an engagement of a hook 24a provided in the lever 24 with the 
projection 22b of the setting plate 22. The second engaging lever 24 is 
formed with an arm 24b at an end opposite to the hook 24a. When the arm 
24b is pushed by the closing operation of the shutter of the camera, the 
lever 24 makes rotation in the clockwise direction against the tensile 
force of the spring 26 so that the hook 24a is disengaged from the 
projection 22b of the setting plate 22. 
The setting plate 22 is adapted to be cooperative with the film winding 
operation in such a manner that at the same time of the shutter setting, 
the setting plate 22 moves in the rightward direction in the drawing 
against the tensile force of the spring 23 so that it comes into an 
engagement with the second engaging lever 24. 
It should be noted here that, though the electromagnet 1 and the iron lever 
2 are shown in the same plane as the other parts and components for the 
sake of convenience of easy understanding, they actually stand in the 
vertical direction with respect to the plane in which other parts and 
components are arranged. Therefore, an aperture of the camera is not 
obstructed by the electromagnet 1 and the iron lever 2. 
Next, the operation of the exposure rate controlling mechanism thus 
constructed will be described. 
An electrical control circuit is provided for controlling both of the coils 
1c and 1d of the electromagnet 1. The electric control circuit is 
connected to a power source through a switch. When the power source switch 
is closed, the electric control circuit provides an output for energizing 
either one of the coils 1c and 1d of energizing neither of these coils 
based on the information on the brightness in the object field or on the 
manually preset diaphragm rate. 
In this case, the power source switch is closed at the initial stage of the 
releasing operation. After that, the first engaging lever 18 is operated 
mechanically or electromagnetically to rotate in the counterclockwise 
direction against the tensile force of the spring 20 so that the arm 18a 
thereof disengages from the bent part 15g of the diaphragm rate 
determining lever 15. 
In a first case in which only the coil 1c is energized, the first iron 
member 5 is drawn and held by the magnetic pole 1a, maintaining the iron 
lever 2 at a position shown by a solid line. Accordingly, the iron 
cooperating lever 7 and the diaphragm control lever 10 are also maintained 
in positions shown by solid lines. As a result of this, the diaphragm rate 
determining lever 15 having disengaged from the first engaging lever 18 as 
mentioned above, is drawn by the counterclockwise rotation of the 
diaphragm operating lever 12 due to the tensile force of the spring 14 to 
swing around the pivot shaft 12a through the idle engagement between the 
shaft 8 and the elongated groove 15a and stopped when the pin 10c of the 
diaphragm control lever 10 comes into the recessed part 15b of the 
diaphragm rate determining lever 15. Accompanying this movement of the 
diaphragm rate determining lever 15, the bent part 15f makes displacement, 
which is followed by the operating arm 21 of the diaphragm operating ring. 
Thus the opening degree of the iris diaphragm is determined. 
In a second case in which only the coil 1d is energized, the diaphragm rate 
determining lever 15 starts to move toward the counterclockwise direction, 
causing the bent part 16a of the holding lever 16 to depart from the bent 
part 10b of the diaphragm control lever 10. Following this departure, the 
iron lever 2 also rotates owing to the tension of the spring 4 in the 
counterclockwise direction until the shaft 2c comes into a contact with 
the opposite side of the elongated groove 6a as shown by a dot-and-dash 
line in FIG. 1. As a result of this, the iron cooperating lever 7 is 
pushed against the tension of the spring 9 to displace the pin 10c of the 
diaphragm control lever 10 to a position indicated by a dot-and-dash line 
in FIG. 1 and then into an engagement with the recessed part 15c as shown 
also by a dot-and-dash line in FIG. 2. Thus the opening degree of the iris 
diaphragm is determined according to the position. 
Finally, a third case is taken up in which neither of the coils 1c and 1d 
are energized. In this case, the iron lever 2 turns in the leftward 
direction to cause the pin 10c of the diaphragm control lever 10 to 
displace to a position indicated by a two-dot-and-dash line in FIG. 1 and 
then come into an engagement with the recessed part 15d as shown by a 
two-dot-and-dash line in FIG. 2. Thus the diaphragm rate determining lever 
15 is stopped, determining the opening degree of the iris diaphragm 
accordingly. 
When the opening degree of the iris diaphragm is determined according to 
the respective operations as stated in the foregoing, the shutter is 
operated to open and then close. The second engaging lever 24 is pushed in 
the arm 24b by the closing movement of the shutter in the clockwise 
direction against the tensile force of the spring 26, causing the hook 24a 
to come out of engagement with the projection 22b of the setting plate 22. 
Consequently, the setting plate 22 moves leftwardly in the drawing owing 
to the tensile force of the spring 23. In the course of this leftward 
movement of the setting plate 22, the arm 22a pushes the bent part 15h, 
thereby turning the diaphragm operating lever 12 in the clockwise 
direction against the tension of the spring 14. Thus, the diaphragm rate 
determining lever 15 is moved leftwardly. 
When the diaphragm rate determining lever 15 comes to the last stage of the 
movement, the bent part 15g is brought into engagement with the arm 18a of 
the second engaging lever 18, returning to the state indicated by a solid 
line in FIG. 1. Also, accompanying the movement of the diaphragm control 
lever 15, the bent part 15f returns the operating arm 21 of the diaphragm 
operating ring not shown to the solid-line position. On the other hand, 
the bent part 16a of the holding lever 16 pushes the bent part 10b to turn 
not only the diaphragm control lever 10 but also the iron cooperating 
lever 7 in the clockwise direction. As a result, the iron members 5 and 6 
are returned through the iron lever 2 to a solid-line position where they 
are respectively in contact with the magnetic poles 1c and 1d of the 
electromagnet 1. 
The setting plate 22, cooperative with the film winding operation, is moved 
rightwardly against the tension of the spring 23 by the setting of the 
shutter (this setting of the shutter also returns the second engaging 
lever 24 to the shown position in FIG. 1) so as to engage with the second 
engaging lever 24. 
The above-mentioned series of movements of the respective parts bring them 
to their starting positions shown by solid lines in FIG. 1. 
The iron cooperating lever 7 and the diaphragm control lever 10 can be 
variously designed such that they are formed in an integral unit. However, 
according to the illustrated construction, since the diaphragm control 
lever 10 is slidable with respect to the iron cooperating lever 7, shocks 
caused by the collision of the pin 10c of the lever 10 with the recessed 
part 15b, 15c or 15d of the diaphragm rate determining lever 15 can be 
effectively absorbed. This results in the reduction of collision noises 
and vibrations and the quick determination of the opening degree of the 
diaphragm. 
Further, the holding lever can be constituted of a spring only and may be 
adapted to act on the iron cooperating lever 7 directly. 
In the illustrated embodiment, the electromagnet 1 is formed in an integral 
unit. However, the electromagnet construction is not limited to the shown 
one but may be constituted of a plurality of separated sections. In such a 
multisectional construction, the number of the magnetic poles and coils of 
the electromagnet 1 can be increased as desired. If the number of iron 
members 6 is also increased correspondently and the respective iron 
members have differently-sized elongated grooves, the amount of 
displacement of the iron lever 2 can be varied according to the same 
number of stages as the iron members 6. 
In this instance, it is natural that the diaphragm rate determining lever 
15 is formed with an increased number of recessed parts each for receiving 
the pin 10c of the diaphragm control lever 10 corresponding to the 
energized state of the coils. 
Further, the electromagnet device can comprise a combination of the 
electromagnet 1, a pair of iron members 5 and 6 and a permanent magnet. In 
this construction, the energization of the coil 1c and/or the coil 1d 
overcomes the magnetic force of the permanent magnet attracting the iron 
lever 2 at a predetermined position. Thus the iron lever 2 is displaced to 
three positions corresponding to whether both of the coils 1c and 1d, only 
one coil 1c or neither of the coils 1c and 1d are energized. 
If a pulse is used for actuating the coils, the actuation timing is so set 
that the actuation starts immediately after the diaphragm rate determining 
lever 15 starts moving to lose its holding function of the iron lever 2. 
It is also possible to modify the engagement structure between the pin 10c 
of the diaphragm control lever 10 and the recessed parts 15b to 15d of the 
diaphragm rate determining lever 15 such that the lefthand end surface of 
the bent part 10b is utilized instead of the pin 10c. In this case, the 
pin 10c is only inserted loosely into the elongated groove 7b of the iron 
cooperating lever 7. 
Further, the diaphragm rate determining lever 15 can be provided with an 
exposure period determining function. In this case, the amount of 
displacement of the bent part 15f is used for determining the length of 
the exposure period. Also, the lever 15 can work as a member determining 
both of the exposure time period of such as a programme shutter and the 
opening degree of the diaphragm. 
Industrial Applicability 
As described in the foregoing, according to the exposure rate controlling 
mechanism of the present invention which employs a release type 
electromagnet device as a controlling means, since the exposure rate 
determining member is imparted with a function for holding pressingly the 
iron member against the electromagnet, both of the members are coupled 
organically, thereby simplifying the entire construction remarkably.