JPH08122610A - Lens barrel - Google Patents

Abstract

PURPOSE: To provide a lens barrel capable of realizing a vent hole for air in space partitioned by two lens holding rings fitted slidably onto the inner peripheral surface of a holding barrel with a simple structure. CONSTITUTION: This lens barrel is provided with a cam cylinder 3, two slidably fitted lens holding rings 22 and 23 fitted slidably onto the inner peripheral surface of the cam cylinder and a moving mechanism for changing the relative position in the optical axial direction of the lens holding ring 22 to the lens holding ring 23. On the outer peripheral surface of the lens holding ring 22, a ventilation groove 22c by notching from one end face 22a of the lens holding ring 22 to the other end face 22b is formed. The cam cylinder 3 is provided with a cam hole 3a opened between a part of the ventilation groove 22c and the inner space of the cam cylinder 3 on the front side of the other end face 22b when viewing from one end face 22a of the lens holding ring 22, in an arbitrary relative position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION A holding cylinder and at least two lens holding rings that hold a lens or a lens group and are slidably fitted on an inner peripheral surface of the holding cylinder, and one of the lens holding ring and the other. A lens barrel having a moving mechanism that changes the relative position of the lens holding ring in the optical axis direction,
Particularly, it relates to a lens barrel attached to a camera.

[0002]

2. Description of the Related Art Two lens holding rings for holding a lens or a lens group are slidably fitted on an inner peripheral surface of a holding cylinder,
A lens barrel for changing the relative position of these two lens holding rings to focus a lens has been known in the related art, and among them, there is one that is used by being attached to a camera.

A conventional lens barrel attached to a camera is provided with a plurality of lens holding rings for holding a lens group necessary for photographing, in addition to the above-mentioned two lens holding rings, and these lens holding rings are provided as described above. In addition to the cylinder, the outer cylinder mounted outside the holding cylinder and the inner cylinder mounted inside the holding cylinder are movably provided. Each lens retaining ring moves to a predetermined position according to the situation when zooming or focusing is performed.

[0004]

By the way, when the relative positional relationship between the above-mentioned two lens holding rings changes during zooming or focusing, the two lens holding rings are accordingly held. The volume of the inner space of the holding cylinder partitioned by the ring changes. The lens is usually fixed inside the lens holding ring, and the lens holding ring slides in the holding barrel. Therefore, the above-mentioned volume change is performed while the inner space of the holding cylinder is substantially sealed. That is, for example, when the distance between the two lens holding rings described above becomes small, the internal air is compressed. When such a phenomenon occurs, the resistance due to the closed air cannot be ignored, and the movement resistance of the lens holding ring increases accordingly. When the movement resistance increases, the amount of operation force for moving the lens holding ring increases, and the operability deteriorates.

Therefore, conventionally, a lens holding ring as shown in FIGS. 7 and 8, for example, has been used. Figure 7
The lens holding ring 31 shown in (1) has a slit-shaped groove 31a formed on its outer peripheral surface as an air vent, which penetrates from one end face to the other end face. When the lens holding ring 31 moves, air moves through this groove. Also, FIG.
A through hole 41a is provided in the lens holding ring 41 shown in, and a shielding member 42 is attached so that light does not leak from the through hole 41a. Air will pass through this through hole 41a.

However, the lens holding ring 3 shown in FIG.
In the case of 1, when the radial position of the groove 31a is close to the optical path, light (arrow E) passes through the groove and leaks. On the other hand, in the case of the lens holding ring 41 shown in FIG. 8, it is necessary to further include the shielding member 42, which increases the number of parts, and
Processing is complicated.

In consideration of such problems, an object of the present invention is to remove air from the air filled in the space partitioned by the two lens retaining rings slidably fitted on the inner peripheral surface of the retaining cylinder. The object is to provide a lens barrel that realizes the above with a simple structure.

[0008]

According to a first aspect of the present invention for achieving the above object, a holding barrel and a lens or a lens group are held and slide on the inner peripheral surface of the holding barrel. A lens mirror having at least two lens retaining rings (lens retaining rings A and B) fitted as much as possible and a moving mechanism for changing the relative position of the lens retaining ring B with respect to the lens retaining ring A in the optical axis direction. In the cylinder, a ventilation groove is formed on the outer peripheral surface of the lens holding ring B from one end surface to the front of the other end surface, and the holding cylinder is provided with the ventilation groove at any relative position. A lens is characterized in that a ventilation passage is provided that opens to a part of the lens holding ring B and an inner space of the holding cylinder that is located ahead of the other end surface of the lens holding ring B. A lens barrel is provided.

According to a second aspect of the present invention for achieving the above object, in the first aspect, the ventilation passage is a groove formed in an inner peripheral surface of the holding cylinder. A lens barrel is provided.

According to a third aspect of the present invention for achieving the above object, in the first aspect, the ventilation passage is an elongated hole formed in the tubular portion of the holding barrel. A lens barrel is provided.

According to a fourth aspect of the present invention for attaining the above object, in the third aspect, the moving mechanism comprises:
The holding cylinder in which the ventilation passage which is a long hole is formed, a cam follower which is provided in the lens retaining ring B and is inserted into the ventilation passage so that a tip portion thereof projects from the ventilation passage, and the ventilation passage. And a guide portion that guides the tip portion projecting from the guide portion in a predetermined moving direction, and the air passage further includes the tip portion of the cam follower that is predetermined according to the rotation of the holding cylinder. There is provided a lens barrel characterized by being configured to move in a moving direction.

According to a fifth aspect of the present invention for achieving the above object, in the first, second or third aspect,
A protrusion is provided on the outer peripheral surface of the lens holding ring B, and the air passage is further formed so as to engage with the protrusion and guide the protrusion in a predetermined movement direction. A lens barrel characterized by the above is provided.

[0013]

In the aspect of the present invention, the air in the inner space of the holding cylinder, which is located ahead of the other end surface of the lens holding ring B, can be discharged through the ventilation passage and the ventilation groove. If the ventilation passage is a groove formed on the inner peripheral surface of the holding cylinder or an elongated hole formed in the cylindrical portion of the holding cylinder, the processing becomes easier. Further, the ventilation passage can also be used as an elongated hole for guiding the tip end portion of the cam follower. The ventilation passage is not limited to the cam follower, and may be for guiding the protrusion provided on the lens holding ring B.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a lens barrel according to the present invention is applied to a camera will be described below with reference to the drawings.

FIG. 1 shows the internal construction of this embodiment. The lens barrel 1 includes a fixed barrel 2 that is detachably attached to a camera body (not shown), and a cam barrel 3 that is slidably fitted to the inner peripheral surface of the fixed barrel 2. Lens holding rings 22 and 23 are slidably fitted to the inner peripheral surface of the cam barrel 3, respectively. The lens group 12 including a plurality of lenses is fixed inside the lens holding ring 22. The lens group 13 is fixed to the lens holding ring 23, and further, the lens holding ring 24 to which the lens group 14 is fixed is fitted. At the tip of the lens barrel 1,
The lens group 11 is provided via the lens holding ring 21.

On the other hand, an operating ring 4 is provided outside the fixed barrel 2. On the outer periphery of the operation ring 4 on the tip side, the operation ring 5
Is fitted. The operation ring 4 is used when zooming is performed. By moving the operation ring 4 straight, each lens group moves forward. Further, the operating ring 5 is used during focusing, and by rotating the operating ring 5, the lens group 12 moves back and forth. In FIG. 1, each lens group is set to a wide state (wide-angle state), and the focus is set to infinity. FIG. 2 shows the state of each lens when zooming to the tele side (tele side) while keeping the focus at infinity. As shown in both figures,
When shifting from the state of FIG. 1 to the state of FIG. 2, the lens groups 12 and 13 are relatively close to each other, and the space 6 between them is
The volume of is reduced. On the contrary, in the lens groups 11 and 12, they move away from each other and the volume of the space 7 increases.

The movement of each lens group is realized by using a plurality of cam mechanisms, one of which is the cam pin 8 implanted in the lens holding ring 22 and the cam pin 8 formed in the cam barrel 3. It is realized by a cam hole 3a for guiding. The cam pin 8 is inserted into the cam hole 3a and further engaged with the optical axis direction hole 9 formed in the key 5a integral with the operation ring 5 at the tip thereof. The optical axis direction hole 9 has a width slightly larger than the diameter of the cam pin 8 and extends in the optical axis direction. The cam barrel 3 rotates during zooming, and the cam pin 8 moves back and forth along the hole 9 in the optical axis direction. The cam barrel 3 is stationary during focusing, and the cam pin 8 moves back and forth along the cam hole 3a. On the outer peripheral surface of the lens holding ring 22, there is formed a ventilation groove 22c that is carved from one end surface 22a of the lens holding ring 22 to the front of the other end surface 22b.

Details of the shape of the cam hole 3a are shown in FIG. FIG. 3 corresponds to FIG. 1, and the positional relationship of each lens group (not shown) in FIG. 3 is set similarly to FIG. In FIG. 2, the cam pin 8 is drawn at a position distant from the ventilation groove 22c, but this is done to simplify the description.
As shown in, it is arranged so as to be adjacent to the ventilation groove 22c. Although not shown in FIG. 3, the cam cylinder 3
The outer peripheral surface of is fixed to the fixed cylinder 1 as shown in FIG.

Even if the position of the lens holding ring 22 relative to the lens holding ring 23 changes due to the movement of the lens holding rings 22 and 23 by zooming, the cam hole 3a partially faces the ventilation groove 22c. The lens holding rings 22, 2 at one end of the cam hole 3a.
It is formed so as to open in the space 6 between the three. Therefore, when shifting from the state of FIG. 1 to the state of FIG. 2, the air in the space 6 flows in from the opening of the cam hole 3a exposed in the space 6, and thereafter, this air flows into the ventilation groove 22c.
And is discharged to the space 7. The air flow is shown as arrow A. By discharging the air in this way, the resistance due to the air is reduced, and the lens holding ring 22 can be smoothly moved. When the state of FIG. 2 shifts to the state of FIG. 1, the air in the space 7 moves to the space 6 via the ventilation groove 22c and the cam hole 3a, and the resistance of the air also decreases.

The positional relationship between the ventilation groove 22c and the cam hole 3a is as follows.
Other than FIG. 3, it is shown in FIGS. More specifically, FIG. 3 corresponds to the state of FIG. 1 as described above, and the focus of each lens group is set to infinity in the wide state. FIG. 4 corresponds to FIG. 2, and the focus is infinity in the telephoto state. Even in the state of FIG. 4, air is allowed to escape as shown by arrow B.

On the other hand, in FIG. 5, the focus is set close to the wide state. Also at this time, the ventilation groove 22c and the cam hole 3a are in the positional relationship as shown in the figure, and the air can flow through them as shown by the arrow C. Further, FIG. 6 shows a case where the tele state is set while keeping the focus close to the air, and the air can flow as shown by an arrow D. Of course, when the state of FIG. 5 is changed to the state of FIG. 6 or the state of FIG. 6 is changed to the state of FIG.

The air vent has been described above centering on the positional relationship between the ventilation groove 22c and the cam hole 3a. However, the cam hole 3a is not always used as an air vent, and the cam barrel 3 is not necessarily used.
Alternatively, a groove may be formed on the inner peripheral surface of, and the groove may be used. Further, the present invention is not limited to a camera and can be used in other optical devices.

[0023]

According to the lens barrel of the present invention, the air filled in the space partitioned by the two lens holding rings slidably fitted on the inner peripheral surface of the holding barrel can be easily removed. It can be realized with a structure.

[0024]

[Brief description of drawings]

FIG. 1 is a configuration diagram (wide / infinite state) showing an embodiment of a lens barrel according to the present invention.

FIG. 2 is a configuration diagram showing an embodiment of a lens barrel according to the present invention (tele / infinite state).

FIG. 3 is an explanatory view (a wide / infinite state) in which a part of an embodiment of the lens barrel according to the present invention is developed.

FIG. 4 is an explanatory view (a telephoto / infinite state) in which a part of an embodiment of the lens barrel according to the present invention is developed.

FIG. 5 is an explanatory view (a wide / close-up state) in which a part of an embodiment of the lens barrel according to the present invention is developed.

FIG. 6 is an explanatory view (telephoto / close-up state) in which a part of an embodiment of the lens barrel according to the present invention is developed.

FIG. 7 is a configuration diagram showing a part of a conventional lens retaining ring.

FIG. 8 is a configuration diagram showing a part of a conventional lens retaining ring.

[Explanation of symbols]

1: lens barrel, 2: fixed barrel, 3: cam barrel, 4,
5: operating ring, 6 and 7: space, 8: cam pin, 9:
Optical axis direction hole, 11, 12, 13, 14: lens group,
21, 22, 23, 24, 31, 41: lens holding ring,
42: Shielding member

Claims (5)

[Claims] 1. A holding barrel and at least two lens holding rings (lens holding ring A, which holds a lens or a lens group and is slidably fitted on an inner peripheral surface of the holding barrel).
B) and a moving mechanism that changes the relative position of the lens holding ring B with respect to the lens holding ring A in the optical axis direction, the outer peripheral surface of the lens holding ring B is A ventilation groove carved up to the front side of the other end surface is formed, and in the holding cylinder, at any of the relative positions, a part of the ventilation groove and the one end surface of the lens holding ring B are seen, A lens barrel, characterized in that an air passage opening to an inner space of the holding barrel located ahead of the other end face is provided. 2. The lens barrel according to claim 1, wherein the air passage is a groove formed on an inner peripheral surface of the holding barrel. 3. The lens barrel according to claim 1, wherein the ventilation passage is an elongated hole formed in a tubular portion of the holding barrel. 4. The moving mechanism according to claim 3, wherein the moving mechanism is provided in the holding cylinder in which the ventilation passage that is a long hole is formed and the lens retaining ring B, and a tip portion thereof projects from the ventilation passage. A cam follower that is inserted into the air passage, and a guide portion that guides the tip portion protruding from the air passage in a predetermined movement direction, and the air passage further includes the holding cylinder. A lens barrel, wherein the tip end portion of the cam follower is formed so as to move in the predetermined movement direction in accordance with the rotation of the lens barrel. 5. The projection according to claim 1, 2 or 3, wherein a projection is provided on the outer peripheral surface of the lens holding ring B, and the air passage further engages with the projection and pre-defines the projection. A lens barrel, which is formed so as to guide in a defined movement direction.