JP2000187262A - Barrier opening/closing mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a barrier mechanism which is made smaller in size, reduces costs and eliminates the need for a large drive force by reducing the number of parts. SOLUTION: This barrier mechanism is provided with a rotatable drive member 5 (5a, 5b), a barrier vane 3, which is disposed at an opening 2a at the tip of an end shell 2 and is supported rotatably on the drive member 5, so as to open and close the opening 2a, a spring 4, which energizes the barrier vane 3 in the B direction and simultaneously energizes a drive ring 5 in the A direction and a fixing member 6, which controlls the rotational extent of the barrier vane 3 by abutting the barrier vane 3 by an energizing force in the B direction, of the spring 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a barrier mechanism for blocking an opening at the tip of a lens barrel of a camera or the like.

[0002]

2. Description of the Related Art A conventional barrier mechanism is shown in a front view of FIG. 1 and a sectional side view of FIG. The lens 1 disposed inside the lens barrel 2 collects a light beam incident from the opening 2a. Drive ring 5
Is rotatably supported in the lens barrel 2 and is urged clockwise (direction A) by a tension spring 7. The drive ring 5 is provided with two barrier blades 3 rotatably supported by a rotation shaft 5a.

The torsion spring 8 presses the bosses 5c and 3b provided on the driving ring 5 and the barrier blade 3 to urge the barrier blade 3 clockwise (in the direction B) with respect to the rotation shaft 5a.
A cam follower 3 a provided on the barrier blade 3 is pressed by a fixed cam 6. The drive ring 5 is provided with an escape groove 5b for the cam follower 3a.

In FIG. 1, a barrier blade 3 is disposed at a position where a cam follower 3a abuts on one end 6a of a cam 6 by a clockwise (A direction) biasing of a driving ring 5 by a tension spring 7. At this time, the cam 6 causes the barrier blade 3
Is restricted, and the barrier blade 3 is in an open state. When the drive ring 5 is rotated counterclockwise (A 'direction), the cam follower 3a moves while abutting on the cam 6, and as shown in FIG.
Is disposed on the other end 6 b of the cam 6. At this time, the cam 6 is formed so that the rotation range of the barrier blade 3 in the direction B is increased, and the barrier blade 3 is closed.

[0005]

According to such a barrier mechanism, a tension spring 7 for urging the drive ring 5 and a torsion spring 8 for urging the barrier blade 3 are required, and the number of parts is large, and the barrier mechanism is difficult. It was large and costly. Further, the boss 5c receives a force in the counterclockwise direction (A ′ direction) by the torsion spring 8 to rotate the drive ring 5 in the counterclockwise direction. Must be. Therefore,
The tension spring 7 becomes large and the barrier mechanism becomes large, and the driving force of the driving ring 5 is required to be large, and the power consumption is increased when the driving ring 5 is driven by a motor.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a barrier mechanism which does not require a large driving force while reducing the size and cost by reducing the number of parts.

[0007]

According to a first aspect of the present invention, there is provided a driving member which is rotatable and which is disposed at an opening at a tip of a lens barrel to open and close the opening. And a barrier blade rotatably supported on the driving member, and connected to the barrier blade to urge the barrier blade in a first rotation direction and apply the drive ring in a second rotation direction. The present invention is characterized in that it comprises a spring to be urged, and a fixing member for restricting the amount of rotation of the barrier wing by contacting the barrier wing by the urging force of the spring in the first turning direction.

According to this configuration, the barrier blade is urged in the first rotation direction by the spring, and the amount of rotation is regulated by the fixing member. The barrier blade is arranged so as to contact a predetermined position of the fixing member in accordance with the rotation of the drive ring, so that the barrier blade is opened and closed.

According to a second aspect of the present invention, in the barrier opening / closing mechanism according to the first aspect, the first rotation direction is set to a direction in which the barrier blade closes. According to this configuration, the barrier blade is urged by the spring in the direction to close the opening, and the closing amount is regulated by the fixing member. The barrier blade is arranged so as to contact a predetermined position of the fixing member in accordance with the rotation of the drive ring, so that the barrier blade is opened and closed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. For convenience of explanation, the same members as those in FIG. 1 of the conventional example are denoted by the same reference numerals. 4 and 5 are a front view and a side sectional view showing the barrier mechanism of the first embodiment.
The drive ring 5 is rotatably supported in the lens barrel 2, and the drive ring 5 is provided with two barrier blades 3 rotatably supported by a rotation shaft 5a.

A cam follower 3 provided on the barrier blade 3
A tension spring 4 is attached to a so as to urge the drive ring 5 clockwise (direction A) via a rotating shaft 5a. The tension force of the tension spring 4 is equal to the rotation axis 5a.
Urges the barrier blade 3 clockwise (in the direction B) by a circumferential component force D against the cam follower 3a to fix the cam follower 3a.
(Fixing member). The drive ring 5 is provided with an escape groove 5b for the cam follower 3a.

In FIG. 1, the barrier blade 3 is disposed at a position where the cam follower 3a abuts on one end 6a of the cam 6 by the clockwise (A direction) biasing of the drive ring 5 by the tension spring 4. At this time, the cam 6 causes the barrier blade 3
Is restricted, and the barrier blade 3 is in an open state. When the drive ring 5 is rotated counterclockwise (A 'direction) against the urging force of the tension spring 4,
The cam follower 3a moves while abutting on the cam 6, and the cam follower 3a is disposed at the other end 6b of the cam 6 as shown in FIG. At this time, the cam 6 is formed so that the rotation range of the barrier blade 3 in the direction B is increased, and the barrier blade 3 is closed.

The rotation of the drive ring 5 in the counterclockwise direction (A 'direction) can be performed by a mechanism shown in FIG. That is, the end surface 5e of the engaging member 5d protruding from the drive ring 5 is formed as an inclined surface, and the input member 9 which is in contact with the inclined surface 5e is provided.
When the input member 9 is advanced in the direction of arrow E, the drive ring 5 is rotated in the direction of arrow A 'while the inclined surface 5e slides. As a result, the driving ring 5 is rotated against the urging force of the tension spring 4 to close the barrier blade 3. When the input member 9 is retracted, the driving ring 5 is actuated by the urging force of the tension spring 4.
Can be rotated in the direction A to open the barrier blade 3 as shown in FIG.

According to such a barrier mechanism, the driving ring 5
Can be performed only by the tension spring 4, and the number of components can be reduced, the barrier mechanism can be reduced in size, and the cost can be reduced. Further, since the urging force of the tension spring 4 can be weakened, the tension spring 7 can be reduced, and the driving force of the drive ring 5 can be reduced, so that power consumption can be reduced when driving the motor. .

FIG. 8 is a front view showing a barrier mechanism according to a second embodiment of the present invention. The difference from the first embodiment is that the biasing direction of the drive ring 5 by the tension spring 4 is changed counterclockwise (A ′).
Direction). Then, the barrier blade 3 is moved to B by the circumferential component D of the pulling force with respect to the rotating shaft 5a.
The cam follower 3a is pressed against the cam 6 by being urged in the direction. The drawing shows a state in which the drive ring 5 is rotated against the bias of the drive ring 5 in the counterclockwise direction (A ′ direction) by the tension spring 4, and the cam follower 3 a is attached to one end 6 a of the cam 6. Are arranged. At this time, the rotation of the barrier blade 3 in the direction B is restricted by the cam 6, and the barrier blade 3 is in an open state.

When the driving ring 5 is rotated counterclockwise (A 'direction) by the urging force of the tension spring 4, the cam follower 3a moves while abutting on the cam 6, and as shown in FIG. 3 a is disposed on the other end 6 b of the cam 6. At this time, the cam 6 is formed so that the rotation range of the barrier blade 3 in the direction B is increased.
Is to be closed. In such a barrier mechanism, the same effect as in the first embodiment can be obtained.

FIG. 10 is a front view showing a barrier mechanism according to a third embodiment of the present invention. The difference from the first embodiment is that the urging direction of the barrier blade 3 by the tension spring 4 is counterclockwise (B 'direction). The cam follower 3a is pressed against the cam 6 by a circumferential component D of the pulling force with respect to the rotating shaft 5a. The cam follower 3 a is disposed at one end 6 a of the cam 6 by the bias of the drive ring 5 in the clockwise direction (A direction) by the extension spring 4. At this time, the amount of rotation of the barrier blade 3 in the direction B 'is increased by the cam 6, and the barrier blade 3 is in an open state.

When the driving ring 5 is turned counterclockwise (A 'direction) against the urging force of the tension spring 4, the cam follower 3a moves while abutting on the cam 6, and the cam follower 3a moves as shown in FIG.
As shown in FIG. 1, a cam follower 3a is disposed at the other end 6b of the cam 6. At this time, the amount of rotation of the barrier blade 3 in the B ′ direction is regulated, and the barrier blade 3 is closed.

With such a barrier mechanism, the same effect as in the first embodiment can be obtained. However, when the barrier blade 3 is closed, after the two barrier blades 3.3 come into contact with each other, the drive ring 5 cannot be further rotated. 5 must be stopped. On the other hand, in the first and second embodiments, even after the two barrier blades 3.3 abut, the driving ring 5
Since only the rotation can be performed, a high precision is not required for the rotation stop position of the drive ring 5. Therefore, the first and second embodiments for urging the barrier blade 3 in the closing direction (B direction) are more preferable.

[0020]

According to the first aspect of the present invention, the urging of the driving ring and the urging of the barrier blade can be performed only by the tension spring, so that the number of parts is reduced, the barrier mechanism is reduced in size, and the cost is reduced. Can be achieved. Further, since the urging force of the tension spring can be weakened, the tension spring 7 can be made smaller, and the driving force of the drive ring can be made smaller, so that power consumption can be reduced when the motor is driven.

According to the second aspect of the present invention, when the barrier ring is closed, even if the drive ring is rotated excessively, only the drive ring can be rotated after the plurality of barrier blades come into contact with each other. High precision is not required for the ring rotation stop position. Therefore,
The barrier mechanism can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a front view of a conventional barrier mechanism in a state where a barrier spring is opened.

FIG. 2 is a side sectional view of a conventional barrier mechanism.

FIG. 3 is a front view of a conventional barrier mechanism in a state where barrier blades are closed.

FIG. 4 is a front view of the barrier mechanism according to the first embodiment of the present invention in a state where barrier blades are opened.

FIG. 5 is a side sectional view of the barrier mechanism according to the first embodiment of the present invention.

FIG. 6 is a front view of the barrier mechanism according to the first embodiment of the present invention in a state where barrier blades are closed.

FIG. 7 is a schematic perspective view of a mechanism that drives a drive ring of the barrier mechanism according to the first embodiment of the present invention.

FIG. 8 is a front view of a barrier mechanism according to a second embodiment of the present invention in a state where barrier blades are open.

FIG. 9 is a front view of the barrier mechanism according to the second embodiment of the present invention in a state where barrier blades are closed.

FIG. 10 is a front view of a barrier mechanism according to a third embodiment of the present invention in a state where barrier blades are open.

FIG. 11 is a front view of a barrier mechanism according to a third embodiment of the present invention in a state where barrier blades are closed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lens 2 Lens barrel 3 Barrier blade 4 Extension spring 5 Drive ring 6 Cam 7 Extension spring 8 Torsion spring

Claims (2)

[Claims] A rotatable driving member, a barrier blade disposed at an opening at a tip of a lens barrel, rotatably supported on the driving member so as to open and close the opening, and the barrier blade. A spring for urging the barrier blade in the first rotation direction and urging the drive ring in the second rotation direction; and a urging force of the spring in the first rotation direction to move the barrier blade. A barrier member that is provided with a fixing member that abuts on the barrier blade to regulate the amount of rotation of the barrier blade. 2. The barrier mechanism according to claim 1, wherein the first rotation direction is a direction in which the barrier blade closes.