JP3322481B2 - Sector opening and closing mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a sector opening / closing mechanism used in a still camera or the like, and more particularly, to a sector opening / closing mechanism capable of reducing an exposure error due to a manufacturing error of a sector driving member. More particularly, the present invention relates to improvement of a sector opening / closing mechanism most suitable for a two-blade sector having a relatively simple structure.

[0002]

2. Description of the Related Art FIG. 5 shows a conventional two-blade sector opening / closing mechanism. In FIG. 5, reference numerals 1 and 2 denote sectors rotatably supported on shafts 1a and 2a, respectively, implanted on a ground plate (not shown). The sector 1 is turned clockwise around the shaft 1a from the closed state shown in the figure. And, when the sector 2 is turned counterclockwise about the axis 2a, the aperture 3 formed on the main plate (not shown) is opened, and the sector 1 is turned counterclockwise about the axis 1a from such an open state, and When the sector 2 is turned clockwise about the axis 2a, the aperture 3 is closed. In FIGS. 5 and 6, reference numeral 4 denotes a sector drive lever for applying a right turning force and a left turning force to the sectors 1 and 2. The sector drive lever 4 is rotatably supported on a shaft 4a on the main plate, and an engaging pin 4b formed on the back surface of the distal end portion of the sector drive lever 4 has an elongated hole 1 formed in the sectors 1 and 2.
b, 2b, and the sector drive lever 4 is
, The sector 1 rotates clockwise and the sector 2 rotates counterclockwise. Conversely, when the sector drive lever 4 rotates clockwise about the axis 4a, the sector 1 rotates counterclockwise and the sector 2 rotates clockwise.

A long hole 1 formed in each of the sectors 1 and 2
The inner widths of b and 2b are formed to be slightly larger than the outer diameter of the engaging pin 4b in order to make the operation of the engaging pin 4b smooth, and to reduce backlash caused by the dimensional difference. For example, biasing force in a shutter closing direction is given by springs 5 and 6, which are examples of biasing means. In the drawings of the present application, only the biasing directions of the springs 5 and 6 are indicated by arrows.

[0004]

By the way, sector 1,
Since 2 is a very thin member, it is formed by punching, but the sector drive lever 4 is generally formed by molding. Since the sector drive lever 4 is a very small member provided around the shutter of the camera, a plurality of molding spaces are formed in a single mold apparatus in consideration of production efficiency, and one molding operation is performed. Multi-cavity machining is generally performed so that a plurality of sector drive levers 4 can be formed by machining. for that reason,
Each sector drive lever 4 has an error in finished dimensions. In particular, if an error occurs in the shaft diameter dimension of the engagement pin 4b, even if the error is within an allowable range centered on the design reference value, the conventional sector drive mechanism may cause an error in the opening diameter formed by the sector. There is a problem that a large error occurs.

[0005] This problem will be described in more detail with reference to FIGS. FIGS. 7 to 9 are explanatory diagrams showing the periphery of the aperture 3 in FIG. 5 extracted. FIG. 7 shows the mechanism of FIG. Exposure opening at the time (hatched area)
The state of is shown. In the case of the conventional mechanism shown in FIG. 5, since the sectors 1 and 2 are urged in the closing direction by the springs 5 and 6, respectively, if the shaft diameter of the engagement pin 4b is smaller than the set diameter, , From the initial state, sector 1 is already at a position counterclockwise from the state shown in FIG.
Sector 2 is in a position clockwise from the state shown in FIG.
Therefore, when the sector drive lever 3 is turned counterclockwise to the position of F8, the aperture formed by the sectors 1 and 2 becomes smaller than expected as shown in FIG. Similarly, when the shaft diameter of the engagement pin 4b is larger than the set diameter, the sector 1 is already in a position clockwise from the state shown in FIG. 5, the opening formed by the sectors 1 and 2 is not as planned as shown in FIG. 9 when the sector drive lever 3 is turned to the left at the position F8. It becomes a large aperture. 5 shows an example in which both the sectors 1 and 2 are urged in the closing direction, there is a case in which both sectors are urged in the opening direction. In the mechanism, since the same bias is applied to the sectors 1 and 2 in either the opening direction or the closing direction, an error is added.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has a small opening and closing effect on sector opening even if a slight error occurs in the shaft diameter of the engaging pin 4b. The purpose is to provide a mechanism. In summary, the sector opening and closing mechanism of the present invention is:
Nos. N to N and a sector drive member engaged with each of the sectors and driving the sector to open and close via the engagement points, each of the sectors being located at the engagement point. On the premise of a mechanism having biasing means that is backlashed, the sectors from No. 1 to No. N alternately apply biasing force in the opening direction and biasing force in the closing direction. The above-mentioned object is achieved by receiving from.

[0007]

According to the present invention, when the sector urged in the opening direction is displaced in the opening direction from the original position due to an error in the shaft diameter dimension of the engagement point, the sector is urged in the closing direction. A sector is displaced in the closing direction from its original position. Conversely, if a sector biased in the opening direction is displaced in the closing direction from its original position, the sector biased in the closing direction is in its original position. Therefore, the error in the opening area is mutually canceled, and the influence on the exposure accuracy can be reduced.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a two-blade sector will be described below with reference to the drawings. FIG. 1 is a mechanism diagram showing one embodiment of the present invention. Since the basic structure is the same as that of the mechanism shown in FIG. 5, the same elements are denoted by the same reference numerals as in FIG. Is omitted. In the embodiment shown in FIG. 1, as a feature point, the sector 1 is a spring 5
The sector 2 receives a left-turning force about the axis 1a (urging force in the direction to close the aperture 3) by the spring 2 and the sector 2 applies a left-turning force about the axis 2a by the spring 7 (urging force in the direction to open the aperture 3). Is receiving.

Therefore, assuming that the initial state when the shaft diameter of the engaging pin 4b is as designed is the state shown in FIG.
When the shaft diameter of the engagement pin 4b is small, the sector 1 is displaced in a direction more closed than in the state shown in FIG. 1, and the sector 2 is displaced in a direction slightly opened than in the state shown in FIG. Conversely, when the shaft diameter of the engagement pin 4b is large, the sector 1 is displaced in a slightly more open direction than in the state shown in FIG. 1, and the sector 2 is displaced in a more closed direction than in the state shown in FIG. I do.

In the mechanism shown in FIG. 1, the sector drive lever 4 is directly or indirectly connected to a drive source (not shown). When the sector drive lever 4 turns left around the shaft 4a, the sector 1 is moved to the shaft 1a. Clockwise around the center, sector 2 is axis 2a
The aperture 3 is opened by turning left around the center. FIG.
In the above, the shaft 4a serving as the rotation center of the sector drive lever 4 may be coaxial with the shaft 2a serving as the rotation center of the sector 2 or the shaft 1a serving as the rotation center of the sector 1. 2 to 4
Indicates the periphery of the aperture 3 when the sector drive lever 4 is turned to the left, for example, to F8, and the opening formed by the sectors 1 and 2 is hatched in each drawing.

FIG. 2 of these drawings shows a case where the shaft diameter of the connecting pin 4b is as designed. Now, assuming that the shaft diameter of the connecting pin 4b is smaller than the design standard value, the sector 1 is displaced in a direction to close the aperture 3 more than the standard as shown in FIG. Is displaced in the direction in which the opening is larger than the standard, so that the errors in the opening area are mutually canceled out in the sectors 1 and 2 and the error in the opening area as a whole is extremely small. Conversely, assuming that the shaft diameter of the connecting pin 4b is larger than the design reference value, as shown in FIG.
Displaces the aperture 3 in the direction that opens the aperture 3 more than the standard. At this time, since the sector 2 displaces the aperture 3 in the direction that closes the aperture 3 more than the standard, the error in the opening area is smaller than that of the sector 1.
And 2 cancel each other out and the error in the opening area as a whole becomes very small. Therefore, according to this embodiment, even if a slight error occurs in the shaft diameter of the connecting pin 4b, the influence on the exposure accuracy is extremely small.

In the above description, an example in which the present invention is applied to an aperture / shutter using two blade sectors is shown, but a plurality of sectors and a sector drive member are connected by one pin. If so, the present invention can be applied to, for example, an iris diaphragm having a larger number of sectors. In this case, it is desirable that the number of sectors be an even number in order to reduce the exposure error, but even in the case of an odd number, the number of sectors is biased in either the opening direction or the closing direction. It goes without saying that the exposure error can be reduced.

[0013]

As described above, according to the present invention, even if there is a slight error in the axial diameter of the connecting pin engaging the sector, the sector urged in the opening direction and the sector urged in the closing direction. Since the direction of displacement with respect to the opening position is opposite to the direction of the opened sector, errors in the opening area are canceled out by both sectors, and the exposure error as a whole can be reduced.

[Brief description of the drawings]

FIG. 1 is a plan view of a sector opening / closing mechanism according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram around an aperture in an open state when an engagement pin has an appropriate size in the mechanism shown in FIG. 1;

FIG. 3 is an explanatory view around an aperture in an open state when an engagement pin is small in the mechanism shown in FIG. 1;

FIG. 4 is an explanatory view around an aperture in an open state when an engagement pin is large in the mechanism shown in FIG. 1;

FIG. 5 is a plan view of a conventional sector opening / closing mechanism.

FIG. 6 is a sectional view of a sector drive lever.

FIG. 7 is an explanatory view around an aperture in an open state when an engagement pin has an appropriate size in the conventional mechanism shown in FIG. 6;

FIG. 8 is an explanatory view around the aperture in an open state when the engagement pin is small in the conventional mechanism shown in FIG. 6;

FIG. 9 is an explanatory view around the aperture in an open state when the engagement pin is large in the conventional mechanism shown in FIG. 6;

[Explanation of symbols]

 1 sector 1a shaft 1b long hole 2 sector 2a shaft 2b long hole 3 aperture 4 sector drive lever 4a shaft 4b engagement pin 5 spring 7 spring

Claims (3)

(57) [Claims] 1 to N each having an independent rotation axis.
And a sector driving member engaged with each of the sectors and driving the opening and closing of the sector through the engagement point, each of the sectors having a play with respect to the engagement point. In the sector opening / closing mechanism having biasing means to be brought closer, each of the sectors from No. 1 to No. N receives alternately a biasing force in the opening direction and a biasing force in the closing direction from the respective biasing means. Sector opening and closing mechanism. 2. An apparatus according to claim 1, further comprising: an even number of sectors each having an independent rotation axis; and sector driving members engaged with each of said sectors and driving said sectors to open and close via said engagement points. In the sector opening / closing mechanism provided with biasing means for moving the sector toward the engagement point, the even-numbered sectors alternately bias the opening direction and the closing direction. A sector opening and closing mechanism characterized by receiving from means. 3. A sector drive member having two sectors each having an independent rotation axis, and a sector drive member engaged with each of the sectors and driving the sector to open and close via the engagement points.
In the sector opening / closing mechanism, wherein each of the sectors has an urging means that is loosened with respect to the engagement point, one of the two sectors applies an urging force in an opening direction and the other of the two sectors The other is a sector opening / closing mechanism that receives a biasing force in the closing direction from each biasing means.