JP3106362B2 - Focal plane shutter braking mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a braking mechanism for a focal plane shutter, and more particularly to a braking mechanism for converting kinetic energy of a shutter blade at the end of traveling into thermal energy due to friction and absorbing the kinetic energy.

[0002]

2. Description of the Related Art In recent years, there has been a demand for a higher speed of a shutter blade group due to a demand for a higher speed at an exposure time synchronized with a flash. Therefore, the braking mechanism is also disclosed in Japanese Utility Model Laid-Open No. 63-115127.
As in the mechanism disclosed in Japanese Patent Application Laid-Open Publication No. H10-209, there has been a need for a mechanism that applies a relatively weak braking force at the beginning of braking and applies a relatively strong braking force to the shutter blade drive lever at the end of braking.

[0003]

However, in such a mechanism, the contact area between the lever and the brake is small, so that it is difficult to obtain the required braking force in terms of construction. Further, since the lever force is concentrated at one point, there is a problem of wear. Also occurred.

[0004]

In the focal plane shutter according to the present invention, the shutter blades are driven and the intermediate portion is moved.
To have a contact surface facing each for braked, and the blade drive lever to rotate around the pivot point is biased in one direction, sliding to one of the sliding and contact surface of the blade drive lever A first brake lever having a moving surface and rotating about a pivot, and a second brake lever having a sliding surface sliding on the other contact surface of the blade drive lever and rotating about the pivot. Brake lever and wing
When the root drive lever rotates, the first brake lever and the second
The sliding surface of the brake lever and the contact surface of the blade drive lever
The first brake lever and the second
Of the brake lever in the direction to approach each other.
1 urging means, and rotation of the second brake lever in one direction.
The second brake so as to impart a resistance to the rotation when moving.
A second urging means for urging the lever in the other direction ,
A relatively weak braking force can be applied in the initial stage of braking, and a relatively strong braking force can be applied to the shutter blade drive lever in the final stage of braking, and the configuration is excellent in wear resistance and durability.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a focal plane shutter according to the present invention, shutter blades are driven, have contact surfaces opposed to each other for braking, and are urged in one direction to rotate about a pivot point. A blade drive lever, a first brake lever having a sliding surface that slides on one contact surface of the blade drive lever and rotating about a shaft fulcrum, and the other contact surface of the blade drive lever. a second brake lever pivots about the having axis fulcrum sliding surface for sliding, the blade drive lever times
First and second brake levers when moving
Frictional force between the sliding surface of the blade and the contact surface of the blade drive lever.
So that the first brake lever and the second brake lever
First urging means for urging the two in a direction approaching each other;
When the second brake lever rotates in one direction,
Move the second brake lever in the other direction to provide resistance
A second biasing means for biasing the blade drive lever, the blade drive lever has a contact portion for braking, and the second brake lever has a contact portion that comes into contact with the contact portion. After the contact surface and the sliding surface slide at the end of rotation, the contact portion comes into contact with the contact portion, and thereafter, the second contact is made against the urging force of the second urging means.
The brake lever is configured to rotate .

According to the above configuration, the blade drive lever is connected to the first brake lever and the second brake lever at the initial stage of braking.
At the end of braking, the blade drive lever biases the second biasing means by a relatively weak braking force caused by sliding friction sandwiched between
A relatively strong braking force can be exerted on the blade drive lever by a reaction force that rotates the second brake lever against the force , and the blade drive lever and the second
Since the first and second brake levers are braked by surface contact, it is possible to provide a braking mechanism of the focal plane shutter having excellent wear resistance.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the illustrated embodiments.

FIG. 1 is a plan view showing a mechanism according to the present invention immediately before exposure, and FIG. 2 is a sectional view of a main part of the mechanism. The front blade drive lever 2 is supported by the shaft 1 and has a drive pin 2a standing thereon. The drive pin 2a transmits a driving force by engaging with an arm (not shown) of an opening blade group that opens and closes by operating a known parallel link mechanism. The leading blade drive lever 2 is biased by a right-handed driving force from a spring 4, and is held by the leading claw 3 in the set state. The front blade drive lever has contact surfaces 2b and 2c for braking.
5 is a front blade brake lever A as a first brake lever, 6 is a front blade brake lever B as a second brake lever, and these are provided in the trajectory of the front blade drive lever 2. It is supported by a shaft 7. The front blade brake lever B6 is provided with leftward rotation by a spring 8 as a second urging means, and has a contact portion 6a that comes into contact with the drive pin 2a. In addition, the leaf springs 9a and 9b as the first urging means use the front blade brake levers A and B.
5 and 6 are provided with a force to adhere to each other. When the leading blade drive lever 2 is driven, the leading blade drive lever 2 is configured to be inserted between the leading blade brake levers A, B5, and 6.

Next, the operation of the above configuration will be described.
First, when the front claw 3 is turned clockwise in conjunction with the release operation, the front blade drive lever 2 is turned clockwise by the force of the spring 4, and the front blade group opens the shutter opening (not shown) in conjunction with that. Activate At this time, the contact surface 2 of the leading blade drive lever 2
The b and 2c slide rightward by sliding the front blade brake levers A5 and B6 sandwiched between the leaf springs 9a and 9b. Thereafter, the drive pin 2a is moved to the front blade brake lever contact portion 6a.
, The front blade brake lever 6 is turned clockwise against the urging force of the spring 8. Accordingly, the braking force is applied to the leading blade drive lever 2 relatively weakly at the beginning of braking and acts relatively strongly at the end of braking to slow down.

[0010] Then, by a rear blade drive mechanism (not shown),
The rear blade group is displaced to a position covering the shutter opening (not shown), and one exposure is completed.

In the above, the brake lever A5 for the front blade and the leaf spring 9a and the brake lever B6 for the front blade and the leaf spring 9b are formed as separate members. However, as shown in FIG. By deforming, it is possible to apply a force in the vertical direction to the operation of the leading blade drive lever 2.

[0012]

According to the configuration of the present invention, the blade drive lever is moved between the first brake lever and the second brake lever in the initial stage of braking.
A relatively weak braking force is applied by being sandwiched between the bar and the bar, and the braking force is applied against the urging force of the second urging means at the end of braking.
By applying a relatively strong braking force to the blade drive lever by rotating the second brake lever, there is an effect that the shutter blade can be stopped safely and reliably even when the shutter blade runs at high speed.

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of a braking mechanism according to the present invention.

FIG. 2 is a cross-sectional view of a main part of the braking mechanism.

FIG. 3 is a sectional view of a main part showing another embodiment of the braking mechanism according to the present invention.

[Explanation of symbols]

2 front blade drive lever 2a drive pin 5 front blade brake lever A 6 front blade brake lever B 8 spring (second biasing means) 9a leaf spring (first biasing means) 9b leaf spring (first Biasing means)

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-174023 (JP, A) JP-A-56-4128 (JP, A) JP-A-58-196528 (JP, A) 46725 (JP, U) Full opening 60-70832 (JP, U) Full opening 62-140526 (JP, U) Full opening 63-115127 (JP, U) Full opening 49-55344 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03B 9/08-9/54 G03B 19/12

Claims (1)

(57) [Claims] 1. A drives the shutter blade, having an abutment surface facing each for the brake to the intermediate portion, and a blade drive lever rotates around the pivot point is biased in one direction, the A first brake lever having a sliding surface that slides on one contact surface of the blade drive lever and rotating about a pivot point; and a slide that slides on the other contact surface of the blade drive lever. A second brake lever having a surface and rotating about a pivot point ;
When the blade drive lever rotates, the first brake lever
And the sliding surface of the second brake lever and the blade drive
The first so as to apply a frictional force to the contact surface of the lever.
The brake lever and the second brake lever
First biasing means for biasing in the approaching direction;
When the brake lever rotates in one direction, it resists the rotation
Move the second brake lever in the other direction so that
A second urging means for urging, wherein the blade drive lever has a contact portion for braking, the second brake lever has a contact portion that contacts the contact portion, after the blade drive lever sliding and the said at pivot end the contact surface the sliding surface, the contact portion is in contact with the contact portion, that
Then, the second bias is opposed to the urging force of the second urging means.
A braking mechanism for a focal plane shutter, characterized by rotating a rake lever.