JPH08129212A - Camera - Google Patents

Abstract

PURPOSE: To minimize the gap between a backmost group and a flare preventing mask and to reduce the aperture part of the flare preventing mask by integrally moving the backmost group with the mask between a collapsing position and the vicinity of a specified zooming position. CONSTITUTION: When a 2nd group unit 8 is somewhat extended to a telephoto side from a wide position, the projecting part of the engaging part 9a of a moving diaphragm 9 comes off from a rail 6d, slips down on a tapered surface, and abuts on an eccentric regulating surface, so that an engaging projection 8b comes off from an engaging hole 9b. Therefore, the diaphragm 9 is released from the 2nd group unit 8. In the case of withdrawing a lens barrel from a telephoto position to the wide position, the 2nd group unit 8 retreats and the diaphragm 9 is pushed out to an aperture side by a stopper 8c. In such a case, the projecting part passes the tapered surface and runs on the rail 6d, and the engaging projection 8b of the 2nd group unit 8 is engaged with the engaging hole 9b. Namely, the 2nd group unit 8 and the diaphragm 9 are integrally moved from the collapsing position to the wide position by the engaging means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera having a movable diaphragm type anti-flare mask for blocking unnecessary harmful light due to internal reflection of a lens system inside an optical system barrel.

[0002]

2. Description of the Related Art Conventionally, in order to block harmful light such as ghost and flare by an optical lens system, first, a harmful light beam is cut inside a zoom lens barrel having a plurality of lens groups movable in the optical axis direction. As a means for moving the moving diaphragm in the optical axis direction in conjunction with the zoom operation, the first method of moving the moving diaphragm by hooking it on a straight guide ring for guiding the movement of the plurality of lens groups in the optical axis direction. Alternatively, the movable diaphragm is closely connected to the rearmost lens group of the plurality of lens groups via a compression spring, and the movable diaphragm is locked at a predetermined position on the way from the wide position to the tele position, while A second method is proposed in which the partial lens group moves toward the objective lens group side while being separated from the movable diaphragm while compressing the compression spring.

[0003]

However, in the above-mentioned conventional example, in the process of the lens barrel extending from the retracted state to the wide position, the rearmost lens group once protrudes from the rear portion of the straight guide ring, and then moves forward. In the case of a lens barrel of the type that turns to the wide end, in the first method of the above-mentioned conventional example, the moving diaphragm does not follow the movement of the rearmost lens group that moves forward at the retracted side from the wide position, so at the wide end A gap is created between the rearmost lens group and the movable diaphragm, and the aperture of the movable diaphragm must be expanded to pass the effective light beam.

Therefore, there arises a problem that the strength of the movable diaphragm is lowered and the effect of cutting harmful light flux at the tele position is lowered.

Further, in the second method of the above-mentioned conventional example, although the above-mentioned problem does not occur, the use of the compression spring causes an increase in the number of parts and the number of steps, and a space for accommodating the compression spring is provided. The problem arises of having to.

It is an object of the present invention to follow the movement of the rearmost lens group from the retracted state to the wide end without using a biasing member such as a compression spring, and while saving space and cost, the opening portion Another object of the present invention is to provide a camera having a moving diaphragm type anti-flare mask with a high flare-cutting effect that minimizes the area.

[0007]

A first configuration for achieving the object of the present invention is, as described in claim 1, a plurality of lens groups movable in the optical axis direction and the plurality of lenses. A straight guide member that prohibits rotation of the group around the optical axis and guides movement in the optical axis direction, and the plurality of lenses that are movable in the optical axis direction and block harmful light beams that have passed through the plurality of lens groups With a mask arranged on the aperture side of the group,
A camera having a zoom lens barrel in which a last group of the plurality of lens groups protrudes and retracts from an end face of the rectilinear guide member between a retracted position of the plurality of lens groups and a predetermined zoom position moving forward. When the last lens group of the plurality of lens groups and the mask are integrally moved in the optical axis direction when the last lens group of the plurality of lens groups moves from the photographing region to the retracted position, the last group and the mask are near a predetermined zoom position. And the engagement state of the last group and the mask by the engagement means so that the mask is released from the last group when the plurality of lens groups are moved from the retracted position to the photographing region. And a disengagement releasing means for disengaging in the vicinity of the predetermined zoom position.

In this structure, the last group moves integrally with the mask between the retracted position and the vicinity of the predetermined zoom position. Therefore, even if the last group projects from the rear end surface of the straight guide member and is retracted again, The gap between the last group and the flare prevention mask can be minimized, and the opening of the flare prevention mask can be made small.

A second structure for achieving the object of the present invention is, as described in claim 2, a plurality of lens groups movable in the optical axis direction, and a rotation around the optical axis of the plurality of lens groups. And a linear guide member that prohibits movement and guides movement in the optical axis direction, and is arranged on the aperture side of the plurality of lens groups that are movable in the optical axis direction and that block harmful light flux that has passed through the plurality of lens groups. A zoom lens barrel in which the last group of the plurality of lens groups protrudes and retracts from the end surface of the straight guide member between a retracted position of the plurality of lens groups and a predetermined zoom position that moves forward. In the camera that has, a protrusion that engages with the mask formed in the last group, an engagement portion that is formed on the mask that is engageable with the protrusion, and the predetermined zoom position when the lens barrel is retracted. Push down the mask in the vicinity A stopper formed in the last group, and a rail formed inside the rear portion of the linear guide member so that the engaging portion is urged to ride inward of the linear guide member when the stopper is pushed down by the mask. An engaging means for engaging the engaging projection with the engaging portion of the mask when the engaging portion rides on the rail of the linear guide member and is urged; and when the lens barrel is extended. In the vicinity of the predetermined zoom position, the engaging portion disengages from the rail and retracts from the engaging projection, whereby the mask is released from the last group and stopped, and at the same time, is held by the linear guide member and is not engaged. It is characterized in that it is provided with a disengagement means in a combined state.

In this structure, in addition to the effect of the above structure, the engaging means and the engaging-disengaging means can be constituted by mechanical elements which effectively utilize the members constituting the lens barrel, and the reliable operation is ensured. Guaranteed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a view showing the schematic arrangement of an embodiment of the present invention, showing a wide-angle state of a two-group zoom.

The drive ring 1 is driven by a zoom gear (not shown).
When it rotates around the optical axis, the drive pin 4 fitted to the key groove 1a formed in the drive ring 1 and fixed to the moving cam ring 3 by the nut 2 receives the driving force, which causes the moving cam ring 3 to move. Rotates around the optical axis. At this time, the helicoid 3a formed on the outer peripheral portion of the moving cam ring 3 that fits with the helicoid 5a formed on the inner peripheral portion of the fixed barrel 5 fixed to the camera body (not shown) receives thrust from the helicoid 5a. The moving cam ring 3 moves in the optical axis direction while rotating.

A linear guide ring 6 is fitted inside the moving cam ring 3, and a projection 6a is fitted in a groove 3b provided inside the moving cam ring 3 to move the linear guide ring 6. It moves integrally with the cam ring 3 in the optical axis direction. However, fixed cylinder 5
The linear guide ring 6 itself is regulated by the key 6b of the linear guide ring 6 that fits into the key groove 5b provided on the inner rear side so as not to rotate around the optical axis. Straight guide ring 6
The group cam pin portion 7a of the first group unit 7 and the second group cam pin portion 8a of the second group unit 8 are fitted into the straight-moving cam hole 6c formed in the long groove along the optical axis. The first group unit and the second group unit 8 including the photographing lens move in the optical axis direction while being fitted into the cam grooves 3c and 3d of the ring 3 and receiving thrust by the rotation of the moving cam ring 3 around the optical axis. Reference numeral 10 denotes a biasing compression spring for biasing the first group unit 7 toward the objective side and the second group unit 8 toward the aperture side to provide a proper interval between the first and second groups.

In FIG. 2, reference numeral 9 denotes a substantially disk-shaped moving diaphragm as a flare preventing mask for cutting harmful light beams inside the lens barrel, and the moving diaphragm 9 has an opening 9e at substantially the center thereof. At the same time, the tongue-shaped engaging portions 9a are formed in the peripheral portion and are bent radially at intervals of 120 degrees and are bent in the substantially optical axis direction. Further, on the inner side surface of the straight guide ring 6, a long groove-shaped eccentricity restricting surface 6e is formed along the optical axis so as to face the engaging portion 9a of the moving diaphragm 9, and the eccentricity restricting surface 6e is formed. Both wall surfaces along the longitudinal direction constitute a rotation restricting surface 6g, and the left and right rotation restricting surfaces 6g respectively have rails 6d.
Are formed. Further, the second group unit 8 is provided with an engaging projection 8b so that the engaging portion 9a of the movable diaphragm 9 can be engaged. In FIG. 1, a state in which the engaging portion 9a of the movable diaphragm 9 inside the lens barrel with the second group unit 8 rides on the rail 6d of the linear guide ring 6 and engages with the engaging projection 8b of the second group unit 8. Is represented.

FIG. 2 shows an engaged state of the movable diaphragm 9 and the rectilinear guide ring 6 in the retracted state shown in FIG. As shown in the figure, the three engaging portions 9a of the movable diaphragm 9 are slightly bent outward from the state parallel to the optical axis (the state of riding on the rail 6d). The eccentricity restricting surface 6e of FIG. In the figure, the engaging portion 9a is the rail 6d.
It shows the state that it has come off.

FIG. 3 is an enlarged detailed view of the engaging portion 9a of the movable diaphragm 9 shown in FIG. 2, and 9b is an elliptic engagement capable of engaging with the engaging projection 8b of the second group unit 8. Holes, 9c are protrusions that ride on the rails 6d, and 9d is the rotation restricting surface 6g.
6f is a taper surface that is provided to smoothly ride on the rail 6d when the protrusion 9c rides on the rail 6d, and 6h is a second group unit 8
Is a relief portion which is continuous with the eccentricity restricting surface 6e when the projection 8b moves in the optical axis direction from the wide position to the tele position. From this state, when a stopper (not shown) formed on the second group unit 8 pushes down the movable diaphragm 9 toward the aperture side,
The protruding portion 9c rides on the rail 6d from the tapered surface 6f, the engaging portion 9a becomes parallel to the optical axis, and the engaging hole 9b and the engaging protrusion 8b engage with each other. Further, in FIG. 3, the engagement portion 9a is retracted from the rail 6d, and the engagement between the engagement hole 9b and the engagement projection 8b is disengaged. Therefore, the second group unit 8 advances toward the objective side and the engagement is continued. Even if the projection 8b enters the escape portion 6h, the movable diaphragm 9 remains stopped with respect to the straight guide ring 6.

Next, the movable diaphragm 9 in the lens barrel feeding process.
The operation of will be described step by step for each zoom position.

FIG. 4 is a view showing a retracted state, in which the projection 8b of the second group unit 8 pulls the movable diaphragm 9 so that the projection 9c of the engaging portion 9a is disengaged from the rail 6d as shown in FIGS. , After the engaging hole 9b is retracted from the engaging protrusion 8b,
It shows a state in which a stopper (not shown) on the camera body side pushes the lens further to the object side.

FIG. 5 shows that when the lens barrel is retracted from the retracted state to the wide position 1, 2
This shows a state in which the second group unit 8 is most protruded from the rear end face of the linear guide ring 6 in the process of the group unit being fed.
In this figure, as compared with FIG. 4, the second group unit 8 retracts relatively to the straight guide ring 6, so that the stopper 8c provided at the rear of the second group unit 8 pushes the movable diaphragm 9 toward the aperture side. put out. At this time, the projecting portion 9c at the tip of the engaging portion 9a passes through the tapered surface 6f, and then the rail 6d gets on and the engaging projection 8b of the second group unit 8 engages with the engaging hole 9b.

After the second group unit 8 in FIG. 5 is most protruded from the rear end face of the linear guide ring 6, the second group unit 8
Shifts to the forward position and shifts to the wide position shown in FIG. In this process, the engaging projection 8b fitted in the engaging hole 9b pulls the engaging portion 9a, so that the movable diaphragm 9 also follows the second group unit 8 and moves forward. Therefore, the distance between the second group unit 8 and the movable diaphragm 9 is minimized as shown in FIG. 1, and therefore the opening area of the opening 9e can be minimized as much as possible. It is possible to increase the mechanical strength of the movable diaphragm and enhance the effect of blocking harmful light beams.

When the second group unit 8 is slightly extended to the telephoto side from the wide position in FIG. 1, the projecting portion 9c of the engaging portion 9a of the movable diaphragm 9 is disengaged from the rail 6d and slides down the tapered surface 6f to cause eccentricity. The engaging hole 9b comes into contact with the restricting surface 6e and the engaging projection 8
It comes off from b. Therefore, the movable diaphragm 9 is released from the second group unit 8, and even if the second group unit 8 moves to a predetermined position in the telescopic state as in the tele position shown in FIG. 6, the movable diaphragm 9 blocks harmful light. Will remain stopped at the most appropriate position.

Next, the operation of the movable diaphragm 9 in the process of retracting the lens barrel will be described.

When the lens barrel is retracted from the tele position shown in FIG. 6 to the wide position shown in FIG. 1, the second group unit 8 retracts and pushes the movable diaphragm 9 toward the aperture side by the stopper 8c.
At this time, the protruding portion 9c passes through the tapered surface 6f and then the rail 6d.
And the engaging protrusion 8b of the second group unit 8 is engaged with the engaging hole 9b.
Engage with. Unlike the state shown in FIG. 1, the wide state in the feeding process is a state in which the stopper 8c of the second group unit 8 and the movable diaphragm 9 are in close contact with each other. And the stopper 8c is
The movable diaphragm 9 is pushed out to the state of FIG.
It will be in the collapsed state.

In the above embodiment, the engaging means for engaging the second group unit 8 and the movable diaphragm 9 and the disengaging means are constituted only by the second group unit 8, the movable diaphragm 9 and the straight guide ring 6.
A space-saving and low-cost engaging means and disengaging means can be realized without using extra members.

Further, since the second group unit 8 and the movable diaphragm 9 are integrally moved by the engaging means from the retracted position to the wide position, the distance between the second group unit 8 and the movable diaphragm 9 is minimized at the wide position. Therefore, the opening area of the opening 9e of the movable diaphragm 9 can be minimized, the mechanical strength of the movable diaphragm 9 can be increased, and the harmful light beam shielding effect can be enhanced. Alternatively, the outer diameter of the entire movable diaphragm 9 can be reduced by the amount corresponding to the reduction in the opening 9e, and a lens barrel with a small diameter can be realized.

Further, the engagement means is not limited to the above embodiment, and various modifications can be considered. For example, the second group unit 8 is provided with an engagement hole and the moving diaphragm 9 is provided with an engagement portion 9.
It is also conceivable to form an engaging projection on a.

[0027]

According to the first aspect of the present invention, by the engaging means for engaging the last group of the plurality of lens groups movable in the optical axis direction and the flare preventing mask for cutting harmful light flux. Since the last group and the mask move integrally between the predetermined zoom positions that move forward from the retracted position, the distance between the last group and the mask can be minimized at the zoom position. The opening can be made smaller.

Therefore, the mechanical strength of the mask can be increased and the effect of shielding harmful light beams can be enhanced. Furthermore, by reducing the outer diameter of the mask, it is possible to reduce the diameter of the lens barrel.

According to the second aspect of the present invention, the engagement between the last group of the plurality of lens groups and the mask and the disengagement operation can be performed with high accuracy and smoothly without adding new parts. You can do it.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing a wide position of a lens barrel in an embodiment of a camera according to the present invention.

FIG. 2 is a perspective view showing an engaged state of a moving diaphragm of the lens barrel of FIG. 1 and a rectilinear guide ring.

FIG. 3 is an enlarged perspective view showing a main part of engagement in FIG.

4 is a schematic cross-sectional view showing a retracted position of the camera barrel of FIG.

5 is a schematic cross-sectional view showing a maximum projection state of the second group unit of the camera barrel of FIG.

6 is a schematic cross-sectional view showing a tele position of the camera barrel of FIG.

[Explanation of symbols]

6 ... Straight guide ring 6d ... Rail 6e ... Eccentricity regulation surface 6f ... Tapered surface 7 ... 1st group unit 8 ... 2nd group unit 8b ... Engagement protrusion 8c ... Stopper 9 ... Moving diaphragm 9a ... Engagement portion 9b ... Engagement hole 9c ... projection

Claims (2)

[Claims] 1. A plurality of lens groups movable in the optical axis direction, a straight guide member for inhibiting the rotation of the plurality of lens groups around the optical axis, and guiding the movement in the optical axis direction, and the optical axis. A mask arranged on the aperture side of the plurality of lens groups that is movable in the direction and blocks harmful light flux that has passed through the plurality of lens groups, and that moves forward from the collapsed position of the plurality of lens groups. In a camera having a zoom lens barrel in which the last group of the plurality of lens groups protrudes and retracts from the end surface of the rectilinear guide member with respect to the zoom position, An engaging means for engaging the last group of the plurality of lens groups and the mask in the vicinity of a predetermined zoom position so as to integrally move the mask in the optical axis direction; and the plurality of lens groups. Taken from the retracted position When you go to the pass,
A camera, comprising: engagement releasing means for releasing the engagement state between the last group and the mask by the engaging means so as to release the mask from the last group in the vicinity of the predetermined zoom position. 2. A plurality of lens groups movable in the optical axis direction, a linear guide member for inhibiting the rotation of the plurality of lens groups around the optical axis, and guiding the movement in the optical axis direction, and the optical axis. A mask arranged on the aperture side of the plurality of lens groups that is movable in the direction and blocks harmful light flux that has passed through the plurality of lens groups, and that moves forward from the collapsed position of the plurality of lens groups. In a camera having a zoom lens barrel in which the last group of the plurality of lens groups protrudes and retracts from the end surface of the rectilinear guide member between the zoom position, and a projection that engages with the mask formed in the last group,
An engaging portion formed on the mask engageable with the protrusion, a stopper formed on the last group to push down the mask in the vicinity of the predetermined zoom position when the lens barrel is retracted, And a rail formed inside the rear portion of the linear guide member so that the engaging portion is urged to ride inward of the linear guide member when the mask of the stopper is pushed down. Means for bringing the engaging projection and the engaging portion of the mask into an engaged state when being urged to ride on the rail, and the engaging portion near a predetermined zoom position when the lens barrel is extended. Is disengaged from the rail and retracted from the engaging projection, the mask is released from the last group and stopped, and at the same time, the mask is held by the linear guide member and disengaged by the disengagement means. A camera characterized by that.