Lens barrel and camera including lens barrel

A lens barrel includes a lens tube configured to hold a lens, a barrier driving member configured to move between an opened state and a closed state by switching of the lens tube between a shooting-ready state and a retracted state, a pair of first barrier blades, each of which includes a blade portion, configured to open and close in conjunction with the barrier driving member, and a pair of second barrier blades, each of which includes a blade portion and a coupling portion, the coupling portion positioned outside the lens as viewed from an object side and located closer to the first barrier blade than the blade portion, the pair of second barrier blades being configured to be moved by contact between the coupling portion and the first barrier blade.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a lens barrel which includes barrier blades configured to open and close a front surface of a photographic lens, mounted on an imaging apparatus such as a camera, to protect the photographic lens.

2. Description of the Related Art

In a retractable-lens camera, which compactly retracts a lens barrel when the camera is carried and extends the lens barrel to move a photographic lens to an appropriate position when the camera is used, various lens barrier mechanisms have been proposed in which barrier blades cover the front surface of the lens when the lens barrel is in its retracted position and the barrier blades are retracted from the front surface of the lens when the camera is in use.

In such a barrier mechanism, the number of barrier blades which constitute the barrier can be selected depending on the effective optical path range of an optical system and the diameter of a lens barrel to effectively cover the front surface of a lens.

This is because there is a limitation on the dimension of the blade which can be stored in a blade storage portion defined by the difference between the diameter of the lens barrel and the effective optical path range of the optical system. Accordingly, with regard to the lens barrels with the same diameter, a larger number of barrier blades are needed as the effective optical path range of the optical system becomes larger.

Accordingly, it is general that a pair of barrier blades is provided to have a bilateral point symmetric relation and each barrier blade covers half of the effective optical path range of the optical system.

However, users tend to demand a zoom lens with a high magnification and a short focal length at the wide-angle end. Thus, the effective optical path range of the front surface of the lens and the optical path range in a space occupied by the barrier in the optical axis direction are considerably widened.

Even though the number of blades constituting the barrier increases to satisfy that demand, the barrier may be thickened in the optical axis direction due to the increase in number of blades. Then, in the space in the optical axis direction, the effective optical path is widened, and the blade storage portion may be narrowed. As a result, the effect of increasing the number of blades may be reduced, so that the space for the barrier in the optical axis direction may be extremely thickened.

Therefore, as a barrier for a lens of a wide-angle system having a short focal length, Japanese Patent Application Laid-Open No. 2007-102086 discusses a technique that decreases the thickness and the size of the barrier.

In the technique discussed in Japanese Patent Application Laid-Open No. 2007-102086, a blade having the largest amount of movement is disposed to be closest to the photographic lens and a second blade is provided with a pair of transmission portions to be pushed by the blade having the largest amount of movement at both its closed and opened sides.

Further, a third blade is provided with a pair of transmission portions to be pushed by the second blade at both its closed and opened sides.

Furthermore, the blade having the largest amount of movement and the third blade are each formed of a metallic sheet to be thin in thickness.

Furthermore, as the transmission portion, the blade having the largest amount of movement is provided with an upward bent portion which is bent in the direction opposite to the lens along the optical axis direction. Further, the third blade is provided with an upward bent portion which is bent toward the lens (the direction toward the imaging plane) along the optical axis direction. Then, since the transmission portion is formed by the upward bent portion, the second blade is formed as a component which is molded from plastic and is formed to be slightly thick.

This is because the upward bent portion, which is bent toward the lens (the direction toward the imaging plane) along the optical axis direction, is provided in either the blade having the largest amount of movement or the second blade. Thus, since there is concern that the lens may be scratched when the upward bent portion passes on the lens, the upward bent portion is not provided in the range overlapping the front lens surface as viewed on the projection plane.

For this reason, in the technique discussed in Japanese Patent Application Laid-Open No. 2007-102086, the second blade is molded from plastic.

SUMMARY OF THE INVENTION

According to an aspect of the invention, a lens barrel includes a lens tube configured to hold a lens, a barrier driving member configured to move between an opened state and a closed state by switching of the lens tube between a shooting-ready state and a retracted state, a pair of first barrier blades, each of which includes a blade portion, configured to open and close in conjunction with the barrier driving member, and a pair of second barrier blades, each of which includes a blade portion and a coupling portion, the coupling portion positioned outside the lens as viewed from an object side and located closer to the first barrier blade than the blade portion, the pair of second barrier blades being configured to be moved by contact between the coupling portion and the first barrier blade.

DESCRIPTION OF THE EMBODIMENTS

Referring toFIGS. 1,2,3, and4, a barrier mechanism which is incorporated in a camera according to an exemplary embodiment of the invention will be schematically described.

FIG. 1is an exploded perspective view illustrating a barrier mechanism according to an exemplary embodiment of the invention.FIG. 2is a front view illustrating a state where a barrier is fully closed,FIG. 3is a front view illustrating a state where the barrier starts to be opened, andFIG. 4is a front view illustrating a state where the barrier is opened. A lens tube3includes a barrier mechanism and is positioned at the front end of the lens barrel when the lens tube3switches from a retracted state to a shooting-ready state. The lens tube3is configured to switch between the shooting-ready state and the retracted state, andFIG. 4illustrates the state of the barrier when the lens tube3is positioned at the shooting-ready state. The barrier mechanism is mounted at the front end of the lens tube3. A photographic lens4is one of a lens group which constitutes a zoom lens, and is a lens which is positioned at the foremost side. An image sensor (not illustrated) is disposed at the rear side of the lens group which constitutes the zoom lens. The lens tube3holds the photographic lens4, and is configured to be retracted and moved forward along the optical axis direction1together with the photographic lens4. The lens tube3is provided with rotation shafts3a, which are formed as rotation shafts of barrier blades7and8constituting the barrier mechanism, and a stopper3b, which regulates the rotation of the barrier blade7in the opening direction via the barrier blade8. The stopper3bis also used as a sticking spot for a barrier cover fixing member9, which is formed of a double-sided adhesive tape for fixing a barrier cover10to the lens tube3.

The lens tube3is provided with a sticking spot3cwhich is used for the barrier cover fixing member9and does not serve as the stopper. In the barrier cover fixing member9illustrated inFIG. 1, after adhesive layers9aand9aare attached to the lens tube3, amount portion9bis removed while the adhesive layers9ais left. The mount9bis used so that the sticking workability is satisfactorily performed and the position of the adhesive layer9ais accurately maintained.

A rectilinear motion tube2, which regulates the rotation of the lens tube3, is disposed inside the lens tube3. According to the switching operation between the retracted state and the shooting-ready state of the lens tube3, the lens tube3relatively moves in the optical axis direction1with respect to the rectilinear motion tube2. In the shooting-ready state, the lens tube3is moved forward relative to the rectilinear motion tube2, so that the distance therebetween is widened. In the retracted state, the lens tube3is moved backward relative to the rectilinear motion tube2, so that the distance therebetween is narrowed.

The rectilinear motion tube2is provided with a cam surface2a, which is configured to close the barrier. The front end of the lens tube3is provided with barrier blades7and8, which are journaled to be rotatable, a barrier driving member5, which drives the barrier blades7and8, and a barrier cover10, in which a photographic opening10ais formed. When the lens tube3is in the retracted state, the barrier blades7and8cover the photographic opening10ato protect the photographic lens4.

The barrier cover10is bonded and fixed to the lens tube3by the barrier cover fixing member9. The barrier driving member5is supported by the lens tube3to be relatively rotatable around the optical axis.

The barrier driving member5is provided with a cam surface5a, which is configured to be pushed by the cam surface2aof the rectilinear motion tube2to close the barrier. The barrier driving member5is provided with rails5e, which allow the barrier blade7to rotate so that the rear surface of the barrier blade7does not come into contact with the photographic lens4. The barrier driving member5is provided with a spring hanger5d, which extends in the radial direction.

Since the arm of the spring hanger5dextends in the radial direction, the position of the barrier driving member5in the optical axis direction can be stably managed. One end of a barrier drive spring6is put on the spring hanger5d. The spring hanger5dis located at a position slightly lower than a spring hanger provided in the barrier blade7so that the barrier drive spring6is slightly obliquely hanged. In a case where a barrier opening spring is used between the barrier driving member5and the lens tube3, the barrier drive spring6is used as a blade closing spring. In this case, the barrier drive spring6may be provided between the lens tube3and the barrier blade7in the direction to close the barrier blades7and8.

In a case where an abnormal operation caused by foreign substances interposed between the blades is absorbed by a portion other than the barrier driving member5and the barrier blade7, the barrier driving member5and the barrier blade7may be coupled to each other by a gear coupling type or a direct coupling type without using an absorbing mechanism such as a shaft and an elongated hole.

The barrier blade7is a blade which is disposed closest to the photographic lens4and has the largest amount of movement, and is formed from a metallic thin sheet.

The barrier blades7and8are specifically illustrated inFIG. 6. A pair of barrier blades7is each provided with a planar support portion7c, which has a rotation hole7bused to attach the barrier blade7to the rotation shaft3aof the lens tube3. The support portion7cis a portion rotating outside the outer shape of the photographic lens4and is located at a position overlapping the photographic lens4as viewed from the side. The barrier blade7is further provided with a step portion7d, which is bent upright in the direction perpendicular to the support portion7c. The step portion7dis also a portion rotating outside the outer shape of the photographic lens4.

The step portion7dis connected with a blade portion7e, which rotates in the area including the front side of the photographic lens4. The blade portion7eis a plane which is parallel to the support portion7c. Since the step portion7dis provided, the rotation hole7bof the support portion7ccan enter the inside of the rotation shaft3aof the lens tube3without increasing the thickness in the optical axis direction. Thus, even when the barrier cover10is floated due to an impact or the like and the barrier blade7is slightly floated in the separation direction, an accident in which the barrier blade7drops out of the shaft does not easily occur.

The rear surface of the blade portion7eslides on the rail5e, which is provided in the barrier driving member5. Since the rear surface slides on the rail5e, the rear surface of the blade portion7eof the barrier blade7can rotate in such a way as not to come into contact with the photographic lens4.

The blade portion7eis provided with sliding portions7fand7g, which maintain a gap with respect to the barrier blade8. The sliding portion7gserves as a closing driving portion for the front end of the barrier blade7. The sliding portion7g, which serves as the closing driving portion, is located at the side opposite the rotation hole7bacross the photographic lens4and at a position not overlapping the photographic lens4as viewed on the projection plane. Thus, the sliding portion7gis located at a position overlapping the photographic lens4in the optical axis direction. The sliding portion7g, which serves as the closing driving portion, drives the barrier blade8in the closing direction by pushing a part of the barrier blade8when the barrier blade7performs a closing operation.

Furthermore, the barrier blade7is provided with an opening driving portion7h, which drives the barrier blade8in the opening direction by pushing a part of the barrier blade8. The opening driving portion7his a part of the edge of the blade portion7e.

A bent portion of the hook7aprotrudes from a part of the support portion7c. The hook7ais a hook which is used for the attachment of the barrier drive spring6. The hook7ais bent by an angle larger than the right angle and is formed so that the attachment portion of the barrier drive spring6tightly and stably contacts the rear surface of the support portion7c.

Referring back toFIG. 1, a tension coil spring is provided as the barrier drive spring6between the barrier blade7and the barrier driving member5. The barrier drive spring6is biased in the direction where the barrier blade7comes into contact with the barrier driving member5, so that the rotation of the barrier driving member5is interlocked with the opening and closing operation of the barrier blade7.

Barrier blade8, which is a second blade, is located on the barrier blade7. The barrier blade8is provided with a pair of transmission portions provided at both its closed and opened sides to be pushed by the barrier blade7. Thus, when the barrier blade7is closed, the barrier blade8is also closed. When the barrier blade7is opened, the barrier blade8is also opened. Furthermore, the barrier blade8is also formed of a metallic thin sheet like the barrier blade7.

Referring toFIG. 6again, the barrier blade8will be specifically described. A pair of barrier blades8is each provided with a planar support portion8c, which has a rotation hole8bused to attach the barrier blade8to the rotation shaft3aof the lens tube3.

The support portion8cis a portion rotating outside the outer shape of the photographic lens4and is located at a position overlapping the photographic lens4as viewed from the side. The barrier blade8is further provided with a step portion8d, which is bent upright in the direction perpendicular to the support portion8c. The step portion8dalso rotates outside the outer shape of the photographic lens4.

The step portion8dis connected with a blade portion8e, which rotates in the area including the front side of the photographic lens4. The blade portion8eis a plane which is parallel to the support portion8c. The rear surface of the blade portion8eslides on the sliding portion7f, which is provided in the barrier blade7, and the sliding portion7g, which serves as the closing driving portion. Due to the sliding action on the sliding portion7g, the rear surface of the blade portion8eof the barrier blade8rotates in such a way as not to come into contact with the blade portion7eof the barrier blade7, so that any scratch is not formed thereon.

The blade portion8eis provided with a sliding portion8f, which maintains a gap with respect to the barrier cover10. Further, in the front end of the barrier blade8, a closing coupling portion8g, which receives a closing driving force, is located outside the photographic lens4as viewed from an object side (the side of an object to be photographed). The closing coupling portion8gis located at a position which is bent from the blade portion8etoward the barrier blade7. The closing coupling portion8gis folded back by an angle equal to or greater than 90° and less than 180°. A retaining portion8his formed to be continued from the closing coupling portion8g. The closing coupling portion8gis a plane portion with which the sliding portion7gserving as the closing driving portion comes into contact. The retaining portion8his located at a position which is further bent from the closing coupling portion8g. The retaining portion8his bent in a V-shape from the blade portion8e. The closing coupling portion8g, the retaining portion8h, and the blade portion8eform a V-shape, so that the sliding portion7gserving as the closing driving portion is retained and the barrier blade7is not flapped. Accordingly, when the barrier blade8is at the closed position, the front end of the barrier blade7can be prevented from swaying in the optical axis direction. The closing coupling portion8gand the retaining portion8hare located at a position not overlapping the photographic lens4as viewed on the projection plane, and are disposed opposite the rotation hole8bacross the photographic lens4. When the barrier is in the closed state, the closing coupling portion8gand the retaining portion8overlap the support portion8cof the other paired barrier blade8as viewed on the projection plane.

The sliding portion7g, which serves as the closing driving portion, pushes the closing coupling portion8gof the barrier blade8to drive the barrier blade8in the closing direction when the barrier blade7performs a closing operation.

At the same time, the retaining portion8h, which is bent in a V-shape, stops the sway of the barrier blade7. Since the retaining portion8his opened in a V-shape, the barrier blade7surely catches the sliding portion7gserving as the closing driving portion, so that no deviation occurs. The rear end of the blade portion8eis provided with an opening coupling portion8iof the barrier blade8. The opening coupling portion8iis bent at a right angle from the blade portion8e, and the operation range thereof does not overlap the photographic lens4as viewed on the projection plane.

When the barrier blade7is opened, the opening driving portion7hdrives the barrier blade8in the opening direction by pushing the opening coupling portion8iof the barrier blade8. A retaining stopper8j, which prevents the flap of the barrier blade8, protrudes from the support portion8cof the barrier blade8, and a sliding portion8fis provided to maintain a gap with respect to the barrier cover10.

Here, referring back toFIG. 1, the phase of the barrier driving member5when the barrier blade7is opened to enter the shooting-ready state is referred to as a ‘barrier opening phase’. Further, the phase of the barrier driving member5when the lens tube3is retracted to close the barrier blade7is referred to as a ‘barrier closing phase’.

Since the barrier driving member5and the rectilinear motion tube2are respectively provided with the cam surfaces2aand5a, when the lens tube3is retracted, the cam surface2aand the cam surface5acome into contact with each other, and the barrier driving member5is forcedly rotated in the direction depicted by the arrow A while charging the barrier drive spring6. When the barrier driving member5rotates up to the ‘barrier closing phase’, the barrier blades7and8are closed.

When the lens tube3is moved forward, the cam surfaces2aand the cam surface5a, which have been in contact with each other, are separated, and the barrier driving member5rotates in the direction depicted by the arrow B while releasing the charging of the barrier drive spring6. When the barrier driving member5rotates up to the ‘barrier opening phase’, the barrier blades7and8are opened.

The barrier driving member5is provided with the spring hanger5d, which extends in the radial direction. Since the arm of the spring hanger5dextends in the radial direction, the position of the barrier driving member5in the optical axis direction can be stably controlled. One end of the barrier drive spring6is put on the spring hanger5d.

Next, referring toFIGS. 1 and 2to5, the operation of the barrier and the charge amount of the barrier drive spring6will be described. Further, inFIGS. 2 to 4, it is assumed that the barrier blade8is removed to specifically describe the present exemplary embodiment.

FIG. 2is a front view illustrating a state where the barrier is fully closed when the lens tube3is in the retracted state.

InFIG. 2, the barrier blade7is biased in the direction depicted by the arrow C by the tension of the barrier drive spring6. In the retracted state, the barrier blade7is maintained in the closed state by the biasing force of the barrier drive spring6.

Further, the barrier driving member5is biased in the rotation direction depicted by the arrow B illustrated inFIG. 1by the tension of the barrier drive spring6. In the retracted state, the rotation in the direction depicted by the arrow B is regulated by the action of the cam surface2aformed in the rectilinear motion tube2. At this time, the charge amount of the barrier drive spring6becomes a value at a fully closed state illustrated inFIG. 5.

FIG. 3is a front view illustrating a state where the lens tube3is slightly moved forward so that the barrier blade7starts to be opened. In this state, since the barrier driving member5and the rectilinear motion tube2relatively move compared to the retracted state, the barrier driving member5slightly rotates in the direction depicted by the arrow B inFIG. 1by the cam surface2aof the rectilinear motion tube2, and comes into contact with the barrier blade7at the contact portion5b. At this time, the charge amount of the barrier drive spring6reduces compared to the fully closed state illustrated inFIG. 5.

FIG. 4is a front view illustrating a state where the lens tube3is further moved forward so that the barrier blade7is fully opened. In this state, the cam surface5aof the barrier driving member5is completely separated from the cam surface2aof the rectilinear motion tube2. For this reason, the barrier driving member5further rotates in the direction depicted by the arrow B, so that the barrier driving member5enters into the ‘barrier opening phase’ and the charge amount of the barrier drive spring6becomes a value at the fully opened state illustrated inFIG. 5.

Although the barrier blade7is pushed in the opening direction at the contact portion5aof the barrier driving member5, the front end of the barrier blade7comes into contact with the stopper3bprovided in the lens tube3, so that the rotation of the barrier blade7in the opening direction is restricted.

Here, another spring hanging method will be described with reference toFIG. 7.

As illustrated inFIG. 7, a rotation shaft14cof the barrier blade14and a hook14bfor the barrier drive spring6provided in the barrier blade14have a distance L4in the radial direction. For this reason, a rotational force is exerted on the barrier blade14around the rotation shaft14c, but the diameter of the lens barrel increases by the distance L4provided in the radial direction. Further, when the distance L4is made to be short to decrease the diameter of the lens barrel, it is difficult to efficiently apply the rotational force to the barrier blade14.

Therefore, an inflection point6amay be provided in the barrier drive spring6, so that the force of the barrier drive spring6is forcedly made to be exerted in the direction depicted by the arrow C inFIGS. 2 to 4. The shape in which the barrier drive spring6has the inflection point6ais provided in the barrier driving member5, but any place and any component may be used as long as the barrier drive spring6may have the inflection point6a.

Further, as a method of providing the inflection point6ato the barrier drive spring6, the barrier driving member5is provided with a semi-circular protrusion5c. However, any method and any shape may be used as long as the barrier drive spring6may have the inflection point6a.

Here, the barrier drive spring6normally comes into contact with the protrusion5c, which is provided in the barrier driving member5, during the opening and closing operation of the barrier blade7. For this reason, since the force of the barrier drive spring6may be efficiently directed to the direction depicted by the arrow C regardless of the opening and closing operation of the barrier blade7, the opening and closing operation of the barrier blade7may be stabilized. Further, since the force may be efficiently exerted in the direction depicted by the arrow C even when the distance is not present between the rotation shaft3aand the hook7ain the radial direction, the diameter of the lens barrel can be shortened and the size of the lens barrel can be decreased.

Next, referring toFIGS. 8A,8B and8C, the motion of the blade of the barrier will be described.FIG. 8Ais a diagram illustrating a state where the barrier is closed,FIG. 8Bis a diagram illustrating a state where the barrier starts to be opened, andFIG. 8Cis a diagram illustrating a state where the barrier is opened.

InFIG. 8A, in which the barrier is closed, the sliding portion7gserving as the closing driving portion pushes the closing coupling portion8gso that the barrier blades7and8are both located at the closed positions. Then, the closing coupling portion8g, which is bent downward from the blade portion8e, and the retaining portion8hare located on the support portions7cand8cof the other paired barrier blades7and8.

The downward bent portion is disposed at a position which is away from the photographic lens4and is above the opposite side. Accordingly, the coupling portion may be sufficiently caught, and the thin thickness of the barrier and the small diameter of the lens barrel may be helpfully maintained.FIG. 11is an enlarged diagram illustrating the sliding portion7gserving as the closing driving portion, the coupling portion8g, the retaining portion8h, and the support portions7cand8cof the opposite barrier blades7and8.

InFIG. 8B, in which the barrier starts to be opened, the barrier blade7moves halfway in the opening direction. On the other hand, the barrier blade8does not move yet.

The timing illustrated inFIG. 8Bindicates the timing at which the opening driving portion7hof the barrier blade7is surely about to push the opening coupling portion8iof the barrier blade8. Since the opening coupling portion8iof the barrier blade8is located outside the photographic lens4as viewed on the projection plane, the downward bent amount of the opening coupling portion8iis sufficiently obtained, and an accident does not happen in which the driving portion7hand the opening coupling portion8ideviate from each other so that the opening force is not transmitted.

InFIG. 8C, in which the barrier is fully opened, the barrier blade7and the barrier blade8are also located at the opened position. Then, the opening driving portion7hof the barrier blade7pushes the opening coupling portion8iof the barrier blade8, so that the rotation of the barrier blade7is restricted by the stopper3b(FIG. 4) via the opening coupling portion8iof the barrier blade8.

With such a configuration, the barrier blade7can be prevented from getting into the gap between the barrier cover10and the stopper3b, which are coupled by the barrier cover fixing member9.

In this way, the barrier blade8is provided with an upward bent portion which is bent toward the lens (the direction toward the imaging plane) along the optical axis direction, the upward bent portion is made so as not to enter the range overlapping the front lens surface as viewed on the projection plane, and the barrier blade7is provided with the closing coupling portion8g, which pushes the barrier blade8in the closing direction, thereby thinning the barrier.

In addition, the support portion7cand the sliding portion7g, serving as the closing driving portion, and the support portion8cand the closing coupling portion8gof the pair of blades are made to overlap as viewed on the projection plane while the support portion7cand the support portion8care lowered in a step shape, thus reducing the thickness of the barrier and reducing the diameter of the lens barrel.

Since two upward bent portions of the opening coupling portion8iand the closing coupling portion8gwith the retaining portion8hare directed toward the photographic lens4in the optical axis direction, there is no need to form an escape portion for the upward bent portion even in the barrier cover10, which forms the opening of the foremost end of the lens barrel and covers the blade. For this reason, since the barrier cover10can be formed by performing a drawing process on a metallic sheet, a thin barrier can be formed.

FIG. 9is a diagram illustrating a retaining stopper for the barrier blade.

The barrier blade7is rotatably attached by inserting the rotation shaft3aprovided in the lens tube3into the rotation hole7b. Then, the barrier drive spring6is hung between the hook7a, which is bent from the support portion7cof the barrier blade7, and the spring hanger5d, which extends from the barrier driving member5in the radial direction. When the barrier is closed, the barrier drive spring6enters into a charged state in which the barrier drive spring6extends at a maximum. Thus, the barrier drive spring6applies a rotational force to the barrier blade7around the line which connects the rotation hole7bof the barrier blade7and the front end of the blade serving as one stopper.

The line connecting the rotation hole7bof the barrier blade7and the front end of the blade is inclined. However, since the position of the hook7ais close to the rotation hole7band is distant from the front end of the blade, the right end of the rotation hole7bis substantially pulled. If the flap is not regulated, the spring hanger5d, the hook7a, and the rotation hole7bare apt to flap so as to be disposed at the straight line. Since the hook7ais bent at an acute angle larger than the right angle, the attachment portion of the barrier drive spring6tightly and stably contacts the rear surface of the support portion7c. Thus, when the spring hanger5d, which extends from the barrier driving member5in the radial direction, is made to be located at a position lower than the hook7a, the spring hanger5d, the hook7a, and the rotation hole7bcan be disposed on the straight line, so that the flap in the pitch direction with respect to the force direction is not caused by the force of the barrier drive spring6.

The flap in the roll direction with respect to the force direction caused by the force of the barrier drive spring6is stopped or reduced in such a manner that the sliding portion7g, serving as the closing driving portion of the front end of the blade, is regulated by the closing coupling portion8gand the retaining portion8hof the barrier blade8.

In this way, although the barrier blade constituting the barrier may be easily flapped by the portion covering the lens and the rotation shaft portion located at the side of the lens and outside the lens, which are bent in a crank shape, the flap of the barrier blade can be handled by the following countermeasure. That is, in order to prevent the flap in the pitch direction with respect to the direction of the force of the spring exerted in the direction in which the barrier is closed, the rotation shaft of the blade, the spring hanging position, and the position of the spring hanger of the barrier driving member of another spring hanger are formed on the straight line. Further, in order to prevent the flap in the roll direction with respect to the direction of the force of the spring exerted in the direction in which the barrier is closed, the retaining portion8hof the barrier blade8is constrained by the closing coupling portion8gand the retaining portion8hlocated at the front end of the barrier blade8.

FIGS. 10A,10B,10C,10D, and10E are diagrams illustrating three barrier blades, in which there is no difference except for the configuration of the blade. Accordingly, the shape of the blade will be described.

FIG. 10Ais a diagram illustrating a state where the barrier including three barrier blades is closed. In the order from the bottom, a barrier blade21, a barrier blade22, and a barrier blade23are located. The two-dotted chain line indicates a part24of the opening of the barrier cover. The outer shape of the photographic lens4is indicated with a circle25.FIG. 10Bis a diagram in which the barrier blades overlap when the barrier is opened. The lowermost barrier blade21is not visible.FIG. 10Cillustrates the barrier blade23, which is formed of a thin metallic sheet. The barrier blade23is provided with a rotation hole23b, a support portion23cas a rotation center, a step portion23d, a blade portion23e, a closing coupling portion23g, and an opening coupling portion23i. Although the description is not repeated since the description is the same as that of the barrier blade8, the closing coupling portion23gand the opening coupling portion23iare upward bent portions which are bent toward the photographic lens4and are located outside the outer shape25of the photographic lens4.

FIG. 10Dillustrates the barrier blade22, which is formed of a thin metallic sheet. The barrier blade22is provided with a rotation hole22b, a support portion22c, a step portion22d, a blade portion22e, a closing coupling portion22g, and an opening coupling portion22i.

Although the description is not repeated since the description is the same as that of the barrier blade8, the closing coupling portion22gand the opening coupling portion22iare upward bent portions which are bent toward the photographic lens4and are located outside the outer shape25of the photographic lens4. When the barrier is closed, the closing coupling portion22gpushes the closing coupling portion23gof the barrier blade23in the direction to close the barrier blade23. Since the opening coupling portion22icomes into contact with the photographic lens4at the rear side of the blade, the opening coupling portion22imoves to the opposite side of the photographic lens4as seen from the rotation hole22b.

Although not illustrated, a retaining portion is provided to the closing coupling portion22g, and the opening driving portion22kis formed with the rear end surface of the blade. When the barrier is opened, the opening driving portion22kpushes the opening coupling portion23iof the barrier blade23in the direction to open the barrier blade23.

FIG. 10Eillustrates the barrier blade21, which is formed of a thin metallic sheet. As in the barrier blade7, the barrier blade21is provided with a hook21a, a rotation hole21b, a support portion21c, a step portion21d, a blade portion21e, a closing driving portion21g, and an opening driving portion21h, in which any sliding portions are not illustrated as well as in the other barrier blades22and23.

When the barrier is closed, the closing driving portion21gpushes the closing coupling portion22gof the barrier blade22in the direction to close the barrier blade22. When the barrier is opened, the opening driving portion21hpushes the opening coupling portion22iof the barrier blade22in the direction to open the barrier blade22.

As described above, even when six blades are provided in total while one side has three blades, a blade located in front of the lens is formed of a thin metallic sheet. Then, the transmission of the rotation operation is performed by the end surface of the lower barrier blade and the downward bent portion which is bent toward the lens from the upper barrier blade provided in the outer periphery of the photographic lens4in such a way as not to overlap the photographic lens4as viewed on the projection plane. Furthermore, a step is formed in the rotation shaft portion so that the downward bent portion for the closing operation overlaps the rotation center of the barrier blade as viewed on the projection plane.

In this way, according to an exemplary embodiment of the invention, a plurality of barrier blades overlapping each other is interlocked with each other at the downward bent portion of a barrier blade which is bent toward the imaging plane and a locking portion formed by using the thickness of the blade, thereby decreasing the thickness of the barrier. Then, since the downward bent portion is formed in such a way as not to overlap a photographic lens covered by the barrier as viewed on the projection plane, all the barrier blades can be formed of a thin metallic sheet, so that a barrier mechanism which is thin in the optical axis direction can be formed. Furthermore, since the downward bent portion overlaps the rotation center of the barrier blade as viewed on the projection plane, the diameter of the lens barrel can be reduced.

This application claims priority from Japanese Patent Application No. 2011-007051 filed Jan. 17, 2011, which is hereby incorporated by reference herein in its entirety.