JPH05323422A - Photographing device - Google Patents

Abstract

PURPOSE:To prevent the adverse influence of the destruction of a lens-barrel, the stopping of a motor, etc., on a driving system by rubbing and engaging an accessory with the lens-barrel in the rotational direction, and fixing the accessory on the lens-barrel in the axial direction. CONSTITUTION:A front frame 2 is screwed on a fixed barrel 1 so as to be drawn out and has a groove 2a engaging with a lens hood 5. Then, the slipping torque of the lens hood 5 is set smaller than the maximum torque of the front frame 2, determined by the starting torque of a motor, by the coefficient of the friction of the lens hood engaging groove 2a and an engaging pawl 6, and the frictional force of the lens hood engaging groove 2a and the engaging pawl 6, is set larger than lens loading torque. Therefore, in an AF state, the rotation of the motor is transmitted to the front frame 2, and the lens hood 5 is rotated/ drawn out together with the front frame 2, but even if external force is imparted to the lens hood 5, the lens hood 5 is slipped and only the front frame 2 is continuously rotated. On the other hand, in an MF state, the lens hood 5 is rotated by a hand, so that the front frame 2 is drawn out in the axial direction while being rotated, to execute focusing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photographing apparatus, and more particularly to a photographing apparatus including a combination of an autofocus (AF) camera and an accessory detachably attached to a lens barrel of the camera. ..

[0002]

2. Description of the Related Art There are various attachment mounting structures for optical devices such as cameras, and the prior art will be described below by taking a lens hood mounting structure for a lens barrel of a camera as an example.

Conventionally, the lens hood has been mainly attached to a lens barrel by fixing the lens hood, such as a screw-in type, a tightening knob type or a bayonet type. Among them, in the tightening knob type mounting structure, the lens hood that is mounted by rotating the tightening knob can be securely and firmly mounted, so that the hood cylinder can be made long and large in diameter, mainly in the telephoto system. Since it is used for lenses, the hood cylinder is generally made of metal. On the inner periphery of the hood barrel of the lens hood, a protrusion member for engaging with a plurality of engagement grooves on the outer periphery of the lens barrel is fixedly provided on a portion other than the portion having the tightening knob.

On the other hand, there is also proposed a mounting structure in which the lens hood is not completely fixed to a lens barrel or the like but is not movable in the axial direction but is relatively movable in the rotational direction.

[0005]

The accessories attached to the optical equipment by the above-mentioned screw-in type, tightening knob type, bayonet type and the like attachment structures are completely fixed so that the attachment structure is essentially immovable. Since the mounting structure is of a type, there is no fear of dropping from the optical device, but the mounting structure and the lens hood described above have the following problems.

(I) With the recent shift to autofocus (AF) in cameras, the lens hood attachment part that rotates during focusing causes the lens hood to also rotate. If you touch it, the driving force will be transmitted to your hand and you will feel uncomfortable.If your hand touches the lens hood, the load on the motor will increase and the driving speed will decrease.In extreme cases, the motor will stop. There was a risk that the autofocus operation would become impossible. (Ii) Since the conventional lens hood is made of metal, it has a considerable weight. On the other hand, since the lens barrel is also heavy,
If the lens hood is attached to the tip of the lens barrel, a large weight is applied to the front side of the camera, and the operability of the camera becomes extremely poor. (Iii) In the above-mentioned tightening knob type mounting structure, when the protruding member provided on the inner circumference of the hood is made of metal, the outer circumference (groove) of the lens barrel is damaged and the appearance is impaired. (Iv) The conventional metal lens hood is expensive because of high manufacturing cost.

On the other hand, when the above-described mounting structure in which the lens hood is mounted so as to be relatively movable in the rotational direction with respect to the optical device is adopted in the autofocus (AF) camera, the following problems occur. there were.

Generally, even an AF camera has an A / M switch for switching between auto focus (AF) and manual focus (MF), and manual focus can be selected.
In a camera provided with the above-mentioned lens hood mounting structure, the following problems occur during MF operation, that is, in a lens having an MF operating ring integrated with the lens hood mounting portion, the lens hood has a bayonet. In the case of a fixed type, the lens hood can be gripped for MF operation, and especially when the lens hood is not attached, the MF operation is performed by gripping the lens hood mounting part near the lens barrel tip. In the case of a lens, it was very convenient and easy to operate.

However, since the lens hood is rotatable in order to solve the above-mentioned AF problem, the MF operation cannot be performed by gripping the lens hood.

An object of the present invention is to solve the above-mentioned problems and provide a photographing apparatus including a new accessory and an optical device having a new accessory mounting structure.

[0011]

In an image pickup apparatus having an accessory (lens hood) mounting structure according to the present invention, the lens barrel is fixed in the optical axis direction and slips with a certain torque or more in the rotational direction. The lens hood is supported by the rotating lens barrel by a member that frictionally engages with the lens barrel. Further, the entire lens hood in the photographing apparatus of the present invention is integrally molded with resin.

[0012]

According to the accessory mounting structure of the present invention, even if the lens hood is touched during AF, the AF operation is not hindered, and the MF operation is performed by gripping the lens hood during MF.

[0013]

1 and 2 show a first embodiment of the present invention.
1 is a fixed barrel of the lens barrel. Reference numeral 2 is a front frame which is screwed to the fixed barrel 1 so as to be able to be rotationally extended, and which is an engaging groove 2 with the lens hood.
a. An optical system 3 is fixed to the front frame 2. An AF drive pinion 4 transmits rotation to the front frame 2 by a motor (not shown). Reference numeral 5 is a lens hood, 6 is an engaging claw, and 7 is a detachable button.

Reference numeral 8 is a spring, and engaging claws 6 are fixed to both ends thereof, and a protrusion 7a of a detachable button 7 is in contact with the center thereof. The spring 8 is locked by the spring locking portion 5a of the lens hood 5.

The position of the spring locking portion 5a is determined by the stroke of the attach / detach button 7 and the stroke of the engaging claw 6. The operating force of the attachment / detachment button 7 is the spring 8, the fulcrum 5a, and the action point 7a.
It can be set arbitrarily according to the relationship with. Also, the engaging claw 6
The charge pressure between the lens hood engagement groove 2a of the front frame 2 and the lens hood engagement groove 2a can be set by the length and the amount of deflection of the spring 8 and the spring locking portion 5a. In this embodiment, the slip torque of the lens hood is set to be smaller than the maximum torque of the front frame 2 which is determined by the starting torque of the motor by the friction coefficient between the lens hood engagement groove 2a and the locking claw 6.

On the other hand, in the AF camera, the lens load torque at the time of focusing is set to be extremely light for speeding up and labor saving, and is further mechanically separated from the AF motor by the A / M switch. Therefore, although the lens load torque is sufficiently small, the frictional force between the lens hood engagement groove portion 2a and the locking claw 6 is set to be larger than the lens load torque.

In the above construction, in the AF state, the rotation of the motor is transmitted to the front frame 2 by the pinion 4, and the optical system 3 is rotated according to the screw lead with the fixed barrel 1 to be extended in the optical axis direction for focusing. At this time, the lens hood 5 is rotated and extended together with the front frame 2, but even if an external force is applied to the lens hood 5, the lens hood and the front frame slip and only the front frame continues to rotate, which interferes with the AF operation. Absent.

On the other hand, in the MF state, the connection between the pinion 4 and the motor is cut off by an A / M changeover switch (not shown). Therefore, by rotating the lens hood 5 by hand, the front frame 2 becomes the fixed cylinder 1. While focusing on the screw lead, it extends in the axial direction for focusing. If rotation is restricted at the end of the rotation operating area of the front frame, the lens hood will slip with respect to the front frame.
No problem at all.

Since the rotation control of the lens hood and the lens barrel is frictional, the lens hood slips when a rotational force larger than necessary is applied, and torque greater than the slip torque is not transmitted, so that the lens barrel is not broken.

Next, another embodiment of the photographing apparatus of the present invention will be described with reference to FIGS. 3 to 5, reference numeral 11 denotes a front frame located at the front end of the lens barrel,
The outer diameter of the front end of the front frame 11 is D1. Reference numeral 12 is an engagement groove having a taper on both sides, and the groove bottom diameter is D2. Reference numeral 13 is a locking portion of the hood where the taper of the groove 12 is extended, and its outer diameter is D3. 14
Is a hood cylinder member formed of resin, and has a integrally formed protrusion member 15, and the protrusion member 15 has a taper substantially equal to the taper of the engagement groove 12 of the front frame 11. , And has an inner diameter D4.

The inner diameter D4 is δ with respect to the center of the hood cylinder member 14.
However, the taper of the protrusion 15 does not change, and the height is gradually reduced. The inner diameter D4 and the outer diameter D of the front frame 11
The relationship with 1 is set to D4> D1. The tightening member A to the lens barrel is the center line xx ′ of the protruding member 15.
Is arranged on the same line, and the tightening member A is composed of the following components. Reference numeral 16 denotes a tightening portion pedestal, which has a screw 16a and a through hole 16b in the inner circumference, and is fixed to the hood cylinder member 14 with a screw or the like.

Reference numeral 17 denotes a tightening knob, which is a screw portion 17a.
And is screwed with the screw 16a of the tightening pedestal 16.
Reference numeral 18 denotes a tightening knob shaft, which is integrated with the tightening knob 17 by a knock pin or the like, and has a tightening washer 1 at one end.
It has 9 bearing parts 18 a and penetrates the tightening pedestal 16.

Reference numeral 20 denotes a tightening piece, which has a taper 20a and a through hole 20b which are substantially the same as the taper of the engaging groove 12 of the lens barrel 11, and the tightening knob shaft 1 is provided in the through hole.
It is retained by 8 and the tightening washer 19 and held.

In the above structure, FIG. 4 is a view showing a state in which the lens hood 14 is to be attached to the front frame 11 of the lens barrel, and the tightening piece 20 is moved by rotating the tightening knob 17 counterclockwise. When the lens hood 14 is loaded by letting it out to a diameter larger than the outer diameter D1 of the front end of the front frame 11 of the lens barrel and the lens hood 14 is inserted, the tightening piece 20 and the projecting member 15 collide with the hood locking portion 13 of the lens barrel front frame 11, and the lens hood is inserted. The position of 14 in the optical axis direction is determined.

When the tightening knob 17 is rotated to the right at this position, the knob shaft 18 slides in the direction of the optical axis along the taper of the tightening piece 20 and the taper of the engaging groove 12 of the lens barrel front frame 11, It engages with the engagement groove 12.

When the tightening knob 17 is further rotated to the right in this state, the projecting member 15 in the opposite direction causes the above-mentioned tightening piece 2 to move.
As in the case of 0, it engages with the taper of the engaging groove 12 of the front frame 11 of the lens barrel, and the lens hood 14 is engaged and held with respect to the front frame 11 of the lens barrel as shown in FIG.

FIG. 6 shows another embodiment of the present invention, in which reference numeral 40 denotes a hood cylinder member made of resin. Reference numeral 41 denotes a protrusion member, which has the same shape as that shown in FIG. 3 and is formed integrally with the hood cylinder member 40.

Further, 42 is the tightening pedestal 16 of the embodiment of FIG.
And is formed integrally with the hood cylinder member 40.

The configuration and operation other than those of the illustrated components 40 to 42 are exactly the same as those of the embodiment shown in FIG.

[0030]

As described above, in the accessory mounting structure of the present invention, the accessory frictionally engages the lens barrel in the rotational direction and is fixed to the lens barrel in the axial direction. Therefore, if the lens hood receives more torque than necessary, it will slip, and even if a torque greater than the slip torque at this time is transmitted, it will not be transmitted to the lens barrel. There is no risk of stopping or adversely affecting the drive system.

Since the accessory of the present invention, that is, the lens hood, is made of resin, the manufacturing cost is low and the weight is lighter than the conventional product. Moreover, by integrally molding the hood cylinder and the protruding member, the weight is reduced, the operability at the time of shooting is improved, and even when the hood itself is impacted, it acts as an elastic body and crushes like a metal. It can also prevent things from becoming unusable.

Further, there is an effect that the appearance of the lens barrel can be guaranteed by using a resin as the protrusion member, and further, there is a maximum effect that it can be provided at a very low cost.

[Brief description of drawings]

FIG. 1 is an enlarged half section view of a lens barrel having an accessory mounting structure according to the present invention and having a lens hood as an accessory attached thereto.

FIG. 2 is a sectional view taken along the line A-A ′ in FIG.

FIG. 3 is a longitudinal sectional view of an accessory and a lens barrel having an accessory mounting structure as another embodiment of the present invention.

FIG. 4 is a cross-sectional view taken along line xx ′ of FIG. 3, showing a state before the lens hood is attached to the lens barrel.

FIG. 5 is a view showing a state in which the lens hood 14 is fixed to the lens barrel in the configuration of FIG.

FIG. 6 is a vertical sectional view of still another embodiment of the present invention.

[Explanation of symbols]

1: Fixed cylinder 2: Front frame 3: Optical system 4: AF drive pinion 5: Lens hood 6: Engaging claw 7: Attachment / detachment button 8: Spring 11: Front frame 12: Engaging groove 13: Lens hood locking part 14: Hood cylinder member (lens hood) 15: Projection member 16: Tightening pedestal 16a: Screw 17: Tightening knob 17a: Screw portion 18: Tightening knob shaft 18a: Bearing portion 19: Tightening washer 20: Tightening piece 20b: Through hole

Claims (2)

[Claims] 1. An imaging apparatus having an optical device such as a camera and an accessory detachably attached to the optical device, wherein an accessory mounting portion of the optical device is rotated by power during autofocus, and a manual When focusing, it is configured so that it can be rotated by gripping the vicinity of the accessory mounting part with a hand, and the accessory mounted on the accessory mounting part does not move relative to the optical device in the optical axis direction. An imaging device having an accessory mounting structure configured to be supported by the optical device while being supported in a rotational direction with a friction torque larger than a load torque during manual focusing. 2. The photographing apparatus according to claim 1, wherein the accessory is integrally molded with resin.