JPS6191633A - Shock absorbing device for shutter blade - Google Patents

Abstract

PURPOSE:To prevent a shutter blade from breaking even when colliding against an obstacle which enters a running path by providing a driving member with a clutch which begins to slide when more than a specific load is applied to the shutter blade in the opposite direction of the running direction. CONSTITUTION:A blade driving lever 10 which is unlocked rotates clockwise together with a driving lever 12 which is friction-coupled by the force of a driving spring 8, and the blade 4 runs as shown by an arrow. If an obstacle S enters a blade running area, the blade 4 collides against it to put a large load on the lever 12. A friction plate is mounted between the levers 10 and 12 to provide a clutch mechanism, but when its frictional force is larger than the shock, a slide is caused and the lever 10 rotates clockwise independently of the lever 12. Therefore, no torque is applied directly to the shutter blade from the spring 8, and its impulsive force is reduced to prevent the blade from breaking.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application) The present invention relates to a device for mitigating the impact on a shutter blade of a focal plane shutter of a camera, particularly a blade-type focal plane shutter divided into a plurality of blades, when the shutter blade is running. .

(Prior Art) Conventionally, in a two-dimensional shutter blade of the type in which a plurality of shutter blades are rotatably mounted on two actuating arms, and the reshutter blades are moved by the rotation of the arms, The power of the spring, which is the shutter driving source, is transmitted to one of the arms via a driving member integrally connected to the arm.

On the other hand, due to the recent demand for expanding the photographic area of cameras, the maximum speed of the shutter has increased to 1/4000 seconds, and in order to achieve this, it is necessary to increase the running speed of the shutter blade.
The weight of shutter blades has been reduced and the drive spring force has been increased.

Therefore, if the speed of the shutter blade is increased with the structure as described above, there is a possibility that an obstacle such as the edge of the film or a finger may accidentally enter the shutter blade travel area of the shutter opening part. When the shutter blade is running, the shutter blade, which has become weak due to its weight reduction, is subject to the force of the stronger drive spring and collides with these obstacles, resulting in fatal damage. It had some drawbacks.

(Summary of the Invention) The present invention eliminates these conventional drawbacks and provides a blade type in which the shutter blade, which is traveling at high speed, will not be damaged even if it collides with an obstacle that enters the travel path. The purpose of this system is to provide a focal plane shutter in which the shutter drive member and the shutter blades are connected via a clutch, and when an excessive load is applied to the shutter blades in the opposite direction to the traveling direction, the shutter blades The structure is such that slippage occurs between the drive member and the drive member.

Embodiments of the present invention will be described below with reference to the drawings.

(Example): iS1 Figure shows a perspective view of a focal plane shutter to which the present invention is applied. In the figure, 1 is a shutter base plate having an opening 1a, and 2 is a cover plate attached to the base plate 1 at a constant distance, and is provided with an opening (not shown) at a position corresponding to the opening 1a. . 3 and 4 are the main plate l
These are the leading and trailing shutter blades held between the shutter plate 2 and the force plate 2. 5 and 5' have their bases pivoted on the main plate 1, and a plurality of divided blades constituting the leading blade are rotatably pivoted so as to form parallel links; 6 and 6' are Like the leading blade arm, the trailing blade arm is pivotally supported by the ground plate l, and a plurality of divided blades 4 are pivotally attached thereto.

12 is an axis Q provided on the main plate 1 concentrically with the axis of the arm 6
A pin 12a implanted at the tip of the rear blade drive lever passes through the arcuate groove 1b of the main plate 1 and fits into the hole of the arm 6, and rotates integrally with the arm 6. The pin 10b is connected to the drive lever 12 to engage the drive lever 12 as shown in FIG. Lever 12 and l
O means spring 1 with friction plate 14 in between as shown in Figure i3.
9 and connected by a predetermined frictional force,
A slipping clutch is formed that starts to slip when a load exceeding the frictional force is applied. 20 indicates a nut for adjusting the pressing force of the spring 19.

Reference numeral 8 denotes a rear blade drive spring, one end of which engages with a pin loa planted on the top surface of the auxiliary lever, and the other end of which engages with an adjustment ratchet fitted to the shaft Q to move the auxiliary lever lO clockwise. It is strong. Reference numeral 18 is a stopper that restricts the final rotational position of the auxiliary lever 10 at the end of trailing blade travel.

Reference numeral 11 designates a leading blade drive lever, which fits into a shaft P provided on the main plate 1 concentrically with the axis of the trailing blade arm 6, and is connected to the arm 6 by a pin lla as in the case of the trailing blade, and is connected to an auxiliary lever 9. ．． A constant pressing force 1j is applied by a spring across the friction member 14 between the two. 7 is the leading blade drive spring, 1
5 indicates a ratchet for adjusting spring force; ratchet 15.
16 is engaged by a spring force adjustment claw shown in the figure. Reference numeral 21 indicated by a two-dot chain line indicates a shutter speed control means, but its detailed shape is omitted.

Next, the operation of this device will be explained.

When the winding operation is performed from the shutter completion state shown in FIG. 1, the drive assist levers 9 and 10 for the leading and trailing blades are rotated counterclockwise around the axes P and Q by a shutter charge member (not shown). and charges the drive springs 7 and 8. The drive lever 11.12 rotates together with the auxiliary lever due to frictional force, and the arms 5.6, 5', 6' connected to it by pins 11a and 12a rotate around their respective axes, and the shutter blades are parallel to each other. When the drive lever 11.12 comes into contact with a stop member (not shown) and stops at the end of the zero-winding operation in which it moves to the travel start position while moving, the auxiliary lever 9. l
Only O rotates against friction, and the lower pins 9b and lOb
The lever stops at the position where it abuts against the side surface of the drive lever 11, 12, and is locked by a locking member (not shown), completing shutter charging. FIG. 2 shows the relationship between the trailing blade drive lever and the auxiliary lever at this time, and since the leading blade is also exactly the same, illustration is omitted. Note that the auxiliary levers 11 and 12 are provided with an absorption mechanism (not shown) for absorbing the overcharge of the auxiliary levers.

Next, when the shutter is released, the leading blade auxiliary lever 9 and the trailing blade auxiliary lever 10 are sequentially unlocked at predetermined seconds intervals, and the shutter blade runs.

4 and 5 show the operating state of the trailing blade drive system during normal operation, and the leading blade system is also described (as it is similar, this will be used as a representative explanation).

When the rear blade drive auxiliary lever 10 is unlocked, the lever 10 receives the force of the drive spring 8 and rotates clockwise integrally with the frictionally coupled drive shaft 8-12. travels in the direction shown by the arrow in FIG. At this time, since the shutter blade operates smoothly with extremely small torque, almost no counterclockwise load is applied to the lever 12 driving the rear blade, and no slipping occurs on the friction plate 14.

When the rear blade 4 reaches the travel completion position and the drive lever 12 contacts a stopper (not shown), a large counterclockwise load is suddenly applied to the lever, causing the rear blade to be driven more than the friction torque on the friction plate 14. The torque of the spring 8 and the torque due to the rotational kinetic energy of the auxiliary lever 10 become larger, causing the friction plate 14 to slip. As a result, the auxiliary lever 10 becomes separate from the drive lever 12, as shown in FIG. Acts as a brake to prevent

Next, FIGS. 6 and 7 show the state when an obstacle S enters the shutter blade running area of the shutter opening, and as in the case described above, only the operation of the rear blade drive system is representative.

FIG. 6 shows the state in which the rear blade starts traveling and before colliding with the obstacle S. The operation up to this point is the same as that shown in FIG. 4, so the explanation will be omitted.

When the rear blade 4 collides with an obstacle S while traveling, a large counterclockwise load is suddenly applied to the rear blade drive lever 12 connected to the shutter blade 4, as shown in FIG. The rear blade drive spring 8
The torque due to the rotational kinetic energy of 8-10 becomes larger, causing slippage in the friction plate 14. This trial 8-1O becomes a separate body with the lever 12 remaining and continues to rotate clockwise until it contacts the stopper 18 at the maximum. Therefore, the torque of the drive spring 8 is not directly transmitted to the shutter blade, and the impact force in the event of a collision is alleviated, so that the shutter blade is not damaged.

(Effects of the Invention) As described above, the present invention provides a clutch in the driving member interposed between the shutter driving force source and the shutter blade, and applies a predetermined load to the shutter blade or the operating member in the opposite direction to the traveling direction. Since the structure is configured so that the shutter blade starts to slide when a load larger than that is applied, if an obstacle enters the shutter blade travel area at the shutter opening and the shutter blade runs, and the shutter blade collides with these obstacles. However, the sliding of the clutch member separates the driving force source from the shutter blade, thereby preventing excessive force from being applied to the shutter blade, thereby preventing damage to the shutter blade.

In addition, when the shutter blade is operating normally without any obstacles, it also acts as a brake to prevent pounding by alleviating the impact force applied to the shutter blade due to the slippage of the clutch member when the shutter blade completes its travel.

Furthermore, since the friction torque on the friction plate can be adjusted, the optimum condition can be obtained depending on the strength (durability) of the shutter blade and the effectiveness of the main brake.

[Brief explanation of drawings]

The figures show one embodiment of the present invention, in which Fig. 1 is a perspective view of the shutter, Fig. 2 is a plan view of the vicinity of the rear blade drive member, and Fig. 3 is a plan view of the vicinity of the rear blade drive member.
The figure is a side view of the rear blade drive member, Figure 4 is a plan view showing the state of the rear blade drive member in the middle of travel, Figure 5 is a plan view showing the completion status IE of the same member, and Figure 6 is an obstacle. FIG. 7 is a plan view showing a state in which the rear blade collides with an obstacle. 1: Shutter base plate, 2: Cover plate, 3.4: Shutter blade, 5.6: Operating arm, 7, 8: Blade driving power source, 9,
10: Drive assist/<-, 11.12: Blade drive lever, 13.14: Friction plate.

Claims (1)

[Claims] It has a leading blade group and a trailing blade group each divided into a plurality of blades,
In a focal lens shutter for a camera in which a driving member interposed between a driving force source and a shutter blade causes the blade group to travel by a driving force transmitted from the driving force source, the shutter blade is subjected to a load greater than a predetermined value in a direction opposite to the traveling direction. A shock absorbing device for a shutter blade, characterized in that the drive member is provided with a clutch that starts slipping when applied.