JP2921797B2 - Lens barrel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel, and more particularly, to a structure for extending a lens barrel used in a still camera, a video camera or the like.

[0002]

2. Description of the Related Art A lens barrel for a camera as disclosed in Japanese Utility Model Laid-Open No. 62-127513 has been proposed. This lens barrel has a structure in which a moving barrel that supports a lens and a holding barrel that holds the moving barrel are screwed together by a helicoid mechanism. When performing focusing, the moving cylinder is rotated relative to the holding cylinder by driving a driving mechanism disposed on the outer peripheral side of the moving cylinder, and the moving cylinder advances and retreats in the optical axis direction according to the helicoid lead by its own rotation. It is supposed to. By the way, in the method of rotating the movable cylinder, a gear portion is formed on a mountain portion of the male helicoid provided on the outer periphery of the movable cylinder, and the drive of the drive mechanism is transmitted to the gear portion.

[0003]

However, as described above, it is very difficult to form a gear portion on a mountain portion of a male helicoid. This is because the tooth width of the male helicoid crest is too narrow and the gear cannot be formed accurately. Further, even if a gear portion is formed on the mountain portion of the male helicoid, there is a disadvantage that the gear portion has a very small tooth width and the strength of the gear portion is extremely weak.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, improve the strength of a gear portion, and provide a novel lens barrel that can be manufactured at lower cost.

[0005]

The present invention achieves the above object.
In this case, the cross section including the optical axis has a trapezoidal shape.
A male helicoid consisting of the ricoid mountain is formed on the outer circumference of the moving cylinder
Female helicoid formed on the inner periphery of the holding cylinder
Screw on the helicoid, and move the moving cylinder to the
The male helicopter in the lens barrel
Adjacent to each other in the helicoid mountain
Between opposing slopes of helicoid peaks
Fill valleys and straddle between adjacent helicoid peaks
At the height where the teeth protrude from the helicoid peak
A gear part is formed, and a drive gear is meshed with this gear part.
And rotating the moving cylinder by rotation of the drive gear
According to the lead of the helicoid mechanism
It is made to advance and retreat.

Further, the play between the male and female helicoids is prevented.
Incorporate a biasing member into the holding cylinder to stop
Elasticity of one of the slopes that make up the helicoid mountain of Id
Uses a configuration that presses and urges the moving cylinder in one direction in the optical axis direction
In some cases, gear teeth formed on the male helicoid
Shift the center of the width in the optical axis direction away from the biasing member
And leave a gap between the shifting member and the gear section.
Is effective in increasing the strength of the embedded part of the biasing member.
It is fruitful.

[0007]

FIG. 2 shows a lens barrel according to an embodiment of the present invention. This lens barrel includes a two-group zoom lens composed of a front lens group 20 composed of five lenses and a rear lens group 21 composed of three lenses in the optical axis P direction with respect to the fixed cylinder 23. It is designed to zoom in and out.

The lens barrel comprises a fixed barrel 23 integrally formed with the camera body, an intermediate barrel 24 helicoidally coupled inside the fixed barrel 23, and a movable cylinder helicoidally coupled inside the intermediate barrel 24. And a cylinder 25. In addition, since the camera body integrally formed with the fixed cylinder 23 is integrally provided with a wall surface 23c forming a film cartridge chamber, a film feeding gear, and the like, conventionally,
In this embodiment, the size of the camera is reduced compared to a camera having a structure in which the camera body and the fixed cylinder are separate members. Reference numeral 22 denotes a front cover that covers the front surface of the camera body.

The front lens group 20 is fixed to the movable barrel 25 by a well-known bayonet coupling or the like.
Behind the lens group 0, a rear group lens 21 is incorporated in a rear group lens frame 29 via a rear group lens frame 28. Reference numeral 26 denotes a shutter block.

The rear lens group 21 is moved forward and backward by the movable barrel 25.
This is performed by moving the rear lens group frame 29 that is helicoidally coupled to the rear lens group frame 28 fixed to the rear lens frame frame 28. The rear lens frame 28 is, as described above,
5 is fixed to the rear end side, and a female helicoid 2
8a are formed. The female helicoid 28a has a male helicoid 29 formed on the outer peripheral surface of the rear group lens frame 29.
a is screwed.

The male helicoid 29a is shown in FIG.
Helicoid mountain 29b having a trapezoidal cross section including the optical axis
Is a three-row male helicoid formed by three stripes, and its development is shown in FIG. The dotted line shown in the figure indicates the center line of the male helicoid valley 29c, and a gear portion 29d shown by a thick solid line in the figure is formed on the pitch of the male helicoid valley 29c. Further, the male helicoid valley 29c is located on the inner peripheral surface of
° holes 30 are provided, and these holes 30
Each of them accommodates a biasing member 31 described later in detail.

As shown in FIG. 1, the biasing member 31 comprises a biasing ball 31a and a spring 31b. The center of the biasing ball 31a is a male helicoid valley 29c.
Are arranged at positions shifted by the dimension A shown in FIG. As a result, the biasing ball 31a comes into contact with one end of the hole 30 and the slope of the male helicoid mountain 29b, so that the rear lens frame 29 is biased rearward with respect to the rear lens frame base 28 in the optical axis P direction. And the backlash of the helicoid mechanism is prevented. The positional relationship between the holes 30 and the valleys 29c of the male helicoid can be expressed by a relational expression of C>B> (D ₁ -D ₂ ) 1/2 when explained by the dimension symbols shown in FIG. The symbol C used in the above relational expression is the one-sided ball 31a and the male helicoid mountain 29.
Male helicoid valley 29 from the position where it contacts the slope of b
The symbol B represents the distance between the center of the hole 30 and the center of the male helicoid valley 29c.

The gear portion 29d is adjacent to the gear portion 29d as shown in FIG.
As if straddling the two sections of the male helicoid mountain 29b that touched,
Between the opposing slopes of these male helicoid mountains 29b
Helicoid valley 29c, and further teeth its male helicopter
It is formed at a height protruding from the id peak 29b.
The rear lens frame 28 is provided with an escape groove at a position corresponding to the gear portion 29d. Further, the center of the tooth width of the gear portion 29d is the male helicoid valley 29.
It is provided shifted from the center line of c by the dimension S shown in FIG.

The drive of a rear lens drive motor 26a built in the shutter block 26 is transmitted to the gear 29d via gears 26b, 26c, 26d, 26e. Therefore, the rear group lens frame 29 is rotated by the driving of the rear group lens driving motor 26a, and advances and retreats in the direction of the optical axis P according to the lead of the male helicoid 29a. The front lens group 20 is a variator lens, and the rear lens group 21 is a lens group that shares a compensator lens and a focusing lens.

The advance / retreat of the front lens group 20 is performed by
The intermediate cylinder 24 advances and retreats with respect to
In response to the advance and retreat of 4, the movable cylinder 25 advances and retreats,
Done. As shown in FIG. 2, a male helicoid 25a is provided on the outer peripheral surface of the movable cylinder 25, and a female helicoid 24a provided in the intermediate cylinder 24 is screwed to the male helicoid 25a. The movable cylinder 25 is a male helicoid 2
It advances and retreats according to the lead of 5a, and linearly advances and retreats along a linear guide member 35 fitted in a groove 25b provided on the inner peripheral surface of the lead. Reference numeral 25e denotes a cover frame attached to the front end side of the movable barrel 25, and reference numeral 25d denotes a lens window provided on the cover frame 25e.

The intermediate cylinder 24 is provided with a fixed cylinder 23
Is provided with a male helicoid 24b screwed into a female helicoid 23a formed on the inner periphery of the male helicoid 2a when the intermediate cylinder 24 is rotated by the intermediate cylinder rotating member 33.
Move forward and backward according to the lead of 4b. On the front end side of the male helicoid 24b, a gear portion 24c is formed with a constant width in the optical axis P direction.

The fixed cylinder 23 is provided with an opening 23b, which is formed along the optical axis P. A shaft 32 serving as a rotation shaft of the intermediate cylinder rotation member 33 is provided outside the opening 23b, and the straight guide member 3 is provided behind the shaft 32.
A guide rod 32a serving as a guide 5 is fixed between the fixed cylinder 23 and the front cover 22 in parallel with the optical axis P.

The intermediate cylinder rotating member 33 is integrally formed with a gear 33a at one end and a helical gear 33a provided to extend helically from the front to the other end of the gear 33b. . The drive of the lens motor 34 provided in the fixed cylinder 23 is transmitted to the gear 33a, whereby the intermediate cylinder rotating member 33 rotates.

The helical gear 33a meshes with the gear portion 24c through the opening 23b, and rotates the intermediate cylinder 24 by driving a lens motor 34. Although the spiral gear 33a is displaced by the rotation of the intermediate cylinder rotating member 33, the displacement of the spiral gear 33a is the same as the advance and retreat of the intermediate cylinder 24, so that the spiral gear 33a and the gear portion 24c The meshing portion moves in the same phase as the advance / retreat of the intermediate cylinder.

A guide cylinder is integrally provided at a portion of the linear guide member 35 which is freely penetrated by the guide rod 32a, and two guide pins 35b are implanted in the guide cylinder. . These guide pins 35b sandwich both slopes of the spiral gear 33a, and move the linear guide member 35 in response to the displacement of the spiral gear 33a.

A flexible board 36 is inserted between the straight guide member 35 and the movable barrel 25. The other end of the flexible substrate 36 is connected to the shutter block 26, and one end is connected to a control circuit or the like disposed in the camera body along the straight guide member 35. Therefore, the flexible substrate 36 is highly flexible and easily bends in response to the movement of the linear guide member 35.

Next, the operation of the above configuration will be briefly described. FIG. 2 shows the retracted position of the lens barrel according to the present embodiment. In this state, the movable barrel 25 and the intermediate barrel 24 are housed in the fixed barrel 23 in the optical axis P direction. I have. Further, the helical gear 33a and the gear portion 24c
Is located on the rear end side in the opening 23b of the fixed cylinder 23. The two guide pins 35b sandwiching both slopes of the spiral gear 33a are connected to the spiral gear 33a.
It is located on the rear end side. For this reason, the straight guide member 35
Is located on the rear end side of the guide rod, and the flexible substrate 36 is in a state of being drawn into the camera body.

When the lens barrel performs zooming and performs focusing corresponding thereto, the lens motor 34 and the rear lens drive motor 26a are driven. The lens motor 34 drives the intermediate cylinder rotating member 33 to rotate clockwise when viewed from the direction of the lens window 25d. As a result, the intermediate cylinder rotating member 33 rotates, and the movable cylinder 25 rotates the male helicoid 2
In accordance with the lead 4b, it is fed straight forward in the front direction of the optical axis P. The rectilinear guide member 35 also moves in response to the displacement of the helical gear 33a. Further, since one end of the flexible board 36 is connected to the shutter block 26, the flexible board 36 is pulled out of the camera body as the straight guide member 35 moves.

During the extension of the front group lens 20, the rear group lens 21 is also extended in response to the extension of the front group lens 20. The extension of the rear group lens 21 is performed by the rear group lens driving motor 2 as described above.
6a. This drive is performed by the gear 26
The power is transmitted to the gear portion 29d via b, 26c, 26d, and 26e. When the drive of the rear group lens driving motor 26a is transmitted to the gear portion 29d, the rear group lens frame 28 rotates with respect to the rear group lens frame base 28, and advances and retreats in the optical axis P direction according to the lead of the male helicoid 29a. .

The rear group lens frame 29 can be moved forward and backward smoothly without backlash because the rear group lens frame base 28 is provided with the biasing member 31. In addition, since the drive during the forward / reverse rotation of the rear lens drive motor 26a is efficiently transmitted to the gear portion 29d, the rear lens frame 29 is accurately advanced and retracted.

Further, the biasing member 31 according to the present embodiment
The center of the one-sided ball 31a is the male helicoid valley 29c
Of the rear group lens frame 29 can be advanced and retracted without play in the gap between the hole 30 and the biasing ball 31a.

In the embodiment according to the present invention, since the male helicoid 29a is a three-row helicoid, the gear portion 29d is shown in FIG. 1 as compared with the case where the gear portion 29d is provided at the center of the male helicoid valley 29c. The thickness T between the biasing member 31 and the gear portion 29d is increased by the S dimension, and the strength around the entrance of the hole 30 is improved.

In this embodiment, the gear portion 29d is formed so as to protrude from the male helicoid mountain 29b.
The present invention is not limited to this, and a gear portion 29d may be formed in the male helicoid valley 29c. In this case, when compared with the prior art in which the gear portion is formed on the male helicoid mountain 29b,
Forming the gear portion 29d in the male helicoid valley 29c can be formed up to the range of both slopes of the male helicoid peak 29b, so that the gear width of the gear portion 29d can be increased and the strength is improved. However, when the method of forming the gear portion 29c is compared with the method of forming the male helicoid valley 29c and the method of protruding from the male helicoid peak 29b at this position, the latter can be formed more easily. Needless to say.

[0029]

As described above, in the lens barrel according to the present invention, the two helicopters adjacent to each other by filling the valleys of the male helicoid.
It straddles the Coid Mountain and has more teeth than the Helicoid Mountain
Since the gear portion is provided at a protruding height, the tooth width of the gear portion can be widened as compared with the related art, and the strength of the gear portion can be improved. Further , as compared with the case where the gear portion is formed at a position lower than the peak portion of the male helicoid, the formation of the gear portion becomes easier and the cost is reduced. Further, by disposing the gear portion adjacent to the biasing member in a direction away from the biasing member, a gap between the biasing member and the gear portion is increased, so that a portion for holding the biasing member is provided. the effect of Ru to improve the strength.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a main part of a helicoid mechanism according to the present invention.

FIG. 2 is a sectional view of a lens barrel according to the present invention.

FIG. 3 is a development view of a male helicoid provided in a rear lens group frame.

[Explanation of symbols]

 Reference Signs List 20 front group lens 21 rear group lens 25 movable barrel 28 rear group lens frame 28a female helicoid 29 rear group lens frame 29a male helicoid 29b male helicoid mountain 29c male helicoid valley 29d gear portion 30 hole 31 bias member 31a bias ball 31b Spring

Claims (2)

(57) [Claims] 1. A moving cylinder for supporting a lens, and a holding cylinder for holding the moving cylinder.
From multiple helicoid peaks with a trapezoidal cross section
Male helicoid is formed on the inner periphery of the holding cylinder.
A female helicoid screwed into the male helicoid is formed.
Ri, in the lens barrel so as to advance and retreat in the optical axis direction with respect to the holding cylinder a Riutsu dynamic cylinder by the rotation of the moving cylinder, of the helicoid mountain portion constituting the male helicoid,
Between adjacent slopes of helicoid peaks adjacent to each other
Helicoid valley that fills and is adjacent to the helicoid valley
Formed between parts, teeth protruding from helicoid peak
A lens barrel, comprising: a gear portion formed at a height that allows the movable barrel to engage with the gear portion to rotate the movable barrel. 2. A moving cylinder for supporting a lens, and a holding cylinder for holding the moving cylinder.
From multiple helicoid peaks with a trapezoidal cross section
Male helicoid is formed on the inner periphery of the holding cylinder.
A female helicoid screwed into the male helicoid is formed.
Ri, in the lens barrel so as to advance and retreat in the optical axis direction with respect to the holding cylinder a Riutsu dynamic cylinder by the rotation of the movable tube, incorporated in the holding tube, a pair of inclined surfaces constituting the helicoid crests A biasing member for elastically pressing one of the movable cylinder and biasing the movable cylinder toward one side in the optical axis direction ;
Adjacent to each other in the helicoid mountain
Helicoid valley between opposing slopes of the helicoid ridge
To fill the area and straddle the adjacent helicoid mountain
Formed and the height of the teeth protruding from the helicoid peak
The optical axis is set so that the center of the tooth width is away from the biasing member.
Gears that are shifted in direction and mesh with this gear
And a driving gear for rotating the movable barrel.