JP2713235B2 - Camera shooting 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 photographic lens barrel of a camera, and more particularly to a helicoid screw for moving a photographic lens in an optical axis direction.

[0002]

2. Description of the Related Art Conventional photographing lens barrels include, for example, FIG.
There is something like that shown in FIG. 3 is a sectional view of a conventional photographing lens barrel. As shown in FIG. 3, a lens holding cylinder 8 for holding a photographing lens 7 includes a helicoid screw 8a,
9a is coupled to the inner peripheral side of the rotating member 3 by screwing. A key groove (not shown) is formed on the inner peripheral side of the lens holding cylinder 8, and a key 11 which engages with the key groove is formed.
Extends in the direction of the optical axis as shown in FIG.
Is fixed to the fixing portion 1a.

The rotating member 3 has a helicoid screw 2 screwed around its outer periphery, and the helicoid screw 2 is fitted and held by the fixed portion 1 a of the camera body 1. The rotating member 3 has a gear 4 engraved on the outer periphery thereof, and the gear 4 is driven to rotate by a motor 5. With the above configuration, when the drive gear 5 is rotated by the motor 6, the gear 4
The rotation member 3 is rotated via. Due to the rotation of the rotating member 3, the rotating member 3 is moved in accordance with the pitch of the helicoid screw 2.
Moves slightly in the optical axis direction while rotating. At this time, the lens holding cylinder 8 also attempts to rotate, but the rotation is
1, the lens holding cylinder 8 is only allowed to move straight along the optical axis without rotating.

[0004] As described above, the focus adjustment operation is performed by the lens holding cylinder 8, that is, the photographing lens 7 moving straight along the optical axis in accordance with the rotation of the rotating member 3. At this time, a light beam incident on the photographing lens 7 (hereinafter, a photographing light beam)
Are imaged on film surface 13 through aperture 12.

[0005]

However, in the above-mentioned prior art, since the helicoid screw 9a is screwed on the inner peripheral side of the rotating member 3 so as to be exposed to the photographing light beam, the photographing light beam A _{1 is provided.} Is reflected from the helicoid screw 9a,
Create problems such as the reflected light A ₂ will be incident on the film surface 13.

In particular, this problem is conspicuous when the lens holding cylinder 8 is extended toward the object and has a long focal length. This is because, as shown in FIG. 3, the more the lens holding barrel 8 is extended toward the object side, the more the crest of the helicoid screw 9a is exposed to the photographing light beam on the inner peripheral side of the rotating member 3. . FIG.
Shows a partially enlarged view of a helicoid screw in a conventional example. As shown in FIG. 4, for helicoid screw 19a is that forms a trapezoidal shape, photographing light beam A ₁ is easily reflected on the crest 19c. Then, the reflected light A ₂ passes through the aperture 12 and is incident on the film surface 13 and adversely affects the film exposure.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and it is an object of the present invention to prevent a photographic light beam from being reflected by a helicoid screw and to suppress the reflected light from being incident on a film surface, thereby adversely affecting film exposure. The aim is to provide no photographic lens barrel.

[0008]

According to the present invention, in order to solve the above-mentioned problems, an optical axis of a taking lens (7) is screwed around an axis so as to be exposed to a taking light beam incident on the taking lens. A camera lens barrel having a female helicoid screw (9a), wherein a projection (9d) is formed on a flat crest (9c) of the helicoid screw (9a), and the projection (9d) is formed. Cuts off a photographing light beam reflected by the helicoid screw (9a) and guided toward the film surface (13), and suppresses the photographing light beam from entering the film surface (13).

[0009] The root (29e) of the helicoid screw (29a) is inclined with respect to the optical axis of the photographing lens (7). The light was prevented from being incident on the film surface (13). Furthermore, forming at least one recess in the flat crest of the helicoid screw (39a) (39c ₁₎ so the flat part is not left (39d), the concave portion (39d), the recess (39d) itself At least the film surface (13)
It was shaped so as to suppress incidence on the top.

[0010]

According to the present invention, the photographing light flux reflected on the flat crest of the helicoid screw and guided toward the film surface is blocked by the projection, and is prevented from being incident on the film surface. There is no adverse effect on film exposure, and no special light blocking member is required.

Further, the photographic light flux reflected at the bottom of the valley is prevented from being incident on the film surface by the shape of the valley itself, so that it does not adversely affect the film exposure.
Furthermore, the imaging light flux reflected by the concave portion is suppressed from being incident on the film surface by the shape of the concave portion itself,
It does not adversely affect film exposure.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a partially enlarged view of a helicoid screw according to a first embodiment of the present invention. In FIG. 1, a protrusion 9d is formed on the crest 9c of the helicoid screw 9a. The protrusion 9d has a triangular shape, and the tip has a sharp shape.

For this reason, the incident light B ₁ incident on the taking lens 7 (not shown) is reflected toward the film surface (not shown) by the crest 9c of the helicoid screw 9a.
₂ is blocked by the projections 9d, and reflects the reflected light B ₃ slopes 9d ₁ to FIG upward direction. Thus, the reflected light B ₂ at the crest 9c is prevented from being incident on the film surface 13, it does not adversely affect the film exposure.

The helicoid screw 9a itself has a projection 9
Since d is formed, no special light shielding member is required. On the other hand, incident light C ₁ is reflected by the valley bottom 9e, the reflected light C ₂ is reflected light C in FIG. 3 upward direction by the inclined surface 9f
Since the light is reflected as ₃ , it is suppressed from being incident on the film surface 13 and does not adversely affect the film exposure.

In the first embodiment described above, the shape of the projection 9d is triangular. However, the present invention is not limited to this. Any shape (for example, a semicircular shape) that can suppress the reflection by itself may be used. However, the shape thereof is preferable as an embodiment because a sharp tip hardly causes reflection of a photographing light beam.

In the first embodiment, the helicoid screw 9 is used.
and slopes 9f of a not made continuous as one side and slopes 9d ₁ of the projecting portion 9d, but may be continuous and the slope 9d ₁ This slope 9f. That is, the shape of the thread of the helicoid screw 9a may be triangular. However, in the present invention, the formation of the projection 9d on the flat crest 9c of the helicoid screw 9a has the following meaning.

That is, a screw having a triangular shape (generally called a triangular screw) is replaced with a helicoid screw 8.
When used for a and 9a, there is play in the screwing of each other. The occurrence of the play is not preferable when the lens holding tube 8 is moved straight in accordance with the rotation of the rotating member 3. This is because the focus adjustment operation is performed by the straight movement of the lens holding tube 8, and if the backlash occurs, the focus adjustment operation cannot be performed accurately.

To avoid such inconvenience, a helicoid screw, that is, a screw having a trapezoidal or angular shape is used. Further, in the first embodiment, as the projection 9d is formed on the female helicoid screw 9a, a concave portion corresponding to the projection 9d is formed in the male helicoid screw 8a.
Is not particularly formed, but even if the concave portion is not formed in the male helicoid screw 8a, there is no influence on the screwing of the two helicoid screws.

In the first embodiment described above, a projection 9d is formed on the crest 9c of the helicoid screw 9a, and the projection 9d is reflected by the helicoid screw 9a and guided toward the film surface 13. was to block the light B _2, in the second embodiment shown below, discloses a solution with respect to the incident light is reflected by the root 9e of helicoid thread 9a.

[0020] This is because in the first embodiment described above, reflected light C ₂ at root 9e of the incident light C _1, so further reflected in FIG. 1 upward direction slopes 9f, adversely affect the film exposure However, considering the case where the height H _{1 of the} peak is low, there is a high possibility that the reflected light C ₂ at the valley bottom 9 e is incident on the film surface 13, which also adversely affects the film exposure. Because it becomes.

Hereinafter, the second embodiment will be described with reference to FIGS. 2 (a) and 2 (b).
This will be described with reference to FIG. FIGS. 2A and 2B show the book
FIG. 6 is a partially enlarged view of a helicoid screw according to a second embodiment of the present invention.
Each is shown. 2 (a) and 2 (b).
In the second embodiment, the valley bottom 29e is inclined with respect to the optical axis.
Was. In FIG. 2A, the valley of the helicoid screw 29a is shown.
So that the bottom 29e goes down from the objective side to the film surface side
It is inclined. And the incident light E₁Is reflected at the valley bottom 29e
Light E_TwoReflected in the direction of the film surface 13 as
Glow E _TwoIndicates that the valley bottom 29e is inclined with respect to the optical axis.
As a result, the reflected light E is reflected on the slope 29f._ThreeAs above in the figure
To reflect.

Therefore, the reflected light E at the valley bottom 29e is
₂ is suppressed from being incident on the film surface 13 and does not adversely affect the film exposure. Now,
The helicoid screw 29a shown in FIG.
Was inclined from the object side to the film surface side, but the helicoid screw 29 shown in FIG.
The difference a 'is that the inclination of the valley bottom 29e' is increased from the object side to the film surface side.

In FIG. 2B, the incident light E ₁ ′ is reflected at the valley bottom 29 e ′ as reflected light E ₂ ′ by following the same optical path as the incident light E ₁ ′. This is because the angle of incidence and the angle of reflection on the same plane are the same, and in this case, the angle of incidence on the valley bottom 29e 'is orthogonal. Accordingly, the reflected light E ₂ ′ at the valley bottom 29 e ′ is not reflected on the film surface side and is suppressed from being incident on the film surface 13, so that it does not adversely affect the film exposure.

The inclination angle of the valley bottom 29 ₁ ′ is shown in FIG.
As shown in (b), if the angle is set such that the incident light E ₁ ′ is reflected on the object side (including the straight line l ₁ ) with respect to the line l ₁ orthogonal to the optical axis O, the reflected light E ₂ ′ Incident on the film surface 13 can be reliably suppressed. next,
A third embodiment of the present invention will be described with reference to FIG.

In the first embodiment described above, the projection 9d is formed on the crest 9c of the helicoid screw 9a.
d has to intercept the reflected light B ₂ guided reflected by the film surface 13 direction helicoid thread 9a. In the third embodiment with respect to this, a recess 39d so that it does not remain flat mountain flat portion at the top 39c ₁ of the helicoid screw 39a.

According to this, the incident light C ₁ is reflected as reflected light C ₂ in the recess 39d. Incident light C _1, the recess 39d
Since incident substantially perpendicular to the slope 39d ₁ caused by the formation, the reflected light C ₂ follows the same optical path as the incident light C _1. Therefore, the reflected light C ₂ at the concave portion 39d is
Since the light is prevented from being incident on the film surface 13 by the concave portion 39d itself, it does not adversely affect the film exposure.

In the third embodiment, the first embodiment,
That is, the protrusion 9d is formed on the crest 9c of the helicoid screw 9a.
In the first embodiment, as compared with the case where
Projection 9d to obtain the effect of suppressing reflection on the memory surface 13.
The height of the mountain is H _TwoWhereas the third
In the embodiment, the height of the mountain is H_ThreeIs different. here
And the height of the mountain, H_ThreeIs the height H of the mountain shown in FIG.₁Equivalent to
is there. In other words, both the first and third embodiments suppress reflection.
Assuming that the same effect can be obtained, the third embodiment
The height of the mountain can be made lower than in one embodiment.

As a result, in the third embodiment, the shape of the helicoid screw can be reduced as a whole without substantially changing the reflection suppressing effect from that of the first embodiment, and thus the size of the taking lens barrel can be reduced. Can contribute.
Further, the height H ₃ of the mountain is set to the height H ₂ of the mountain in the first embodiment.
Since the slope 39f can be longer than the slope 9f, the helicoid screw can be firmly connected.

In the third embodiment, the recess 39d
Is formed, but a plurality of recesses 49d may be formed as shown in FIGS. 6 (a) and 6 (b) and FIGS. 7 (a) and 7 (b). In FIG. 6 (b) showing a partial enlarged view of FIG. 6 (a), the photographic lens 7 incident light D ₁ which is incident on the (not shown), as reflected light D ₂ is one of the slope 49d ₁ of the concave portion 49d Reflected and further reflected light D ₂
Reflects the upward direction in the figure as reflected light D ₃ at the slope 49d _2.

Therefore, the reflected light D at the concave portion 49d
₃ is prevented from being incident on the film surface 13 by the concave portion 49d itself, and thus does not adversely affect the film exposure. Further, in FIG. 7 (b) showing a partially enlarged portion of FIG. 7 (a), a slope 49d ₁ ′ and a slope 49d
Forming a flat surface 49d ₃ between ₂ '. In this case, the incident light D ₁ ′ incident on the photographing lens 7 (not shown)
Represents the reflected light D on one slope 49d 'of the recess 49d.
Reflected to the object side as ₂ '.

FIG. 7 (b) is replaced with FIG. 6 (b).
Compare with the one shown in (b). First, in the case shown in FIG. 6 (b), the slope 49d ₁ is formed because the interval between the respective projections 49c caused by the formation of the recess 49d is narrow.
In which again reflected reflected reflected light D ₂ is the slope 49d _2, the reflected light D ₃ is heading upward in the drawing.

[0032] On the contrary, those shown in FIG. 7 (b), by providing the flat portion 49d _3, in the interval adjacent each protrusion 49c 'with each other it can take a relatively wide, slopes 49d ₁ The reflected light D ₂ ′ is reflected to the object side as it is. Therefore, the one shown in FIG. 7B is superior to the one shown in FIG. 6B in that the reflected light is not guided to the film surface side. The slope 49
d _1, 49d incident angle of 'incident light D _1, D _1' with respect to ₁ to each other and equivalent.

In the third embodiment, the formation of the recess 39d is performed.
Two projections 39c caused by _TwoTip angle α₁And β
₁Are formed substantially equal to each other, but are not necessarily formed at the same angle.
You do not need to do this. For example, as shown in FIG.
Raised part 59c_TwoEach tip angle α_Two, Β _Twoabout,
Objective tip angle α_TwoIs the tip angle β on the film side._Twothan
It may be large.

[0034] In FIG. 8 (a), the photographic lens 7 incident light F ₁ incident on the (not shown), the inclined surface of the recess 59d 59d
Reflected as reflected light F ₂ in _1, further reflected light F ₂ is reflected as reflected light F ₃ slopes 59d _2, further reflected light F ₃ also is reflected as reflected light F ₄ at the slope 59d _2. The reflected light F ₃ and F ₄ follow the same optical path as the reflected light F ₂ and the incident light F ₁ , respectively.

Therefore, the reflected light F at the concave portion 59d
₃ is prevented from being incident on the film surface 13 by the concave portion 59d itself, and thus does not adversely affect the film exposure. Also, those shown in FIG. 8 (a), the incident light F ₁ has occurred three reflections by the respective slopes 59d _1, 59d _2, the damping effect of the incident light F ₁ is exerted by these reflections You.

This damping effect is similar to that shown in FIG.
Without limiting, the larger the number of reflections, the larger
Helicoid screws are black or matte
If so, it will be more effective. By this
The light incident on the film surface
The amount should be as small as possible. Furthermore, FIG.
As shown in FIG._Two′ Each tip
Angle α _Three, Β_ThreeFor the tip angle α on the objective side_ThreeThe film
Surface side tip angle β_ThreeIt may be smaller than that.

In FIG. 8B, the incident light F ₁ ′ incident on the photographing lens 7 (not shown) is applied to the slope 5 of the concave portion 59 d ′.
It reflected upward in the drawing as "reflected light F ₂ in '9d _1.
Therefore, the reflected light F ₂ ′ at the concave portion 59d ′ is
9d 'itself suppresses incidence on the film surface 13, so that it does not adversely affect film exposure.

[0038]

According to the present invention, the photographing light beam reflected on the flat crest of the helicoid screw and guided toward the film surface is blocked by the projection, and is prevented from entering the film surface. Therefore, there is no adverse effect on the film exposure, and no special light shielding member is required.

Further, the photographing light beam reflected at the bottom of the valley is prevented from being incident on the film surface by the shape of the valley itself, so that it does not adversely affect the film exposure.
Furthermore, the imaging light flux reflected by the concave portion is suppressed from being incident on the film surface by the shape of the concave portion itself,
It does not adversely affect film exposure.

[Brief description of the drawings]

FIG. 1 is a partially enlarged view of a helicoid screw according to a first embodiment of the present invention.

FIGS. 2A and 2B are partially enlarged views of a helicoid screw according to a second embodiment.

FIG. 3 is a sectional view of a photographing lens barrel having a helicoid screw in a conventional example.

FIG. 4 is a partially enlarged view of a helicoid screw in a conventional example.

FIG. 5 is a partially enlarged view of a helicoid screw according to a third embodiment.

FIG. 6 (a) is a partially enlarged view of a helicoid screw which is a modification of the third embodiment. (B) is a partially enlarged view of (a).

FIG. 7A is a partially enlarged view of a helicoid screw which is a modification of the third embodiment. 6B is a partially enlarged view of FIGS. 6A and 7A, respectively.

FIGS. 8A and 8B are partially enlarged views of a helicoid screw which is a modification of the third embodiment.

[Explanation of symbols]

 3 ... Rotating member 7 ... Photographing lens 8 ... Lens holding cylinder 8a, 9a ... Helicoid screw 9c ... Top 9d ... Projection 9e ... Bottom 9f ... Slope 11 ・ ・ ・ Key 12 ・ ・ ・ Aperture 13 ・ ・ ・ Film surface 39d ・ ・ ・ Recess

Claims (3)

(57) [Claims] 1. A photographic lens barrel of a camera having a female helicoid screw threaded around an optical axis of a photographic lens and exposed to a photographic light beam incident on the photographic lens, wherein the female helicoid is provided. A projection is formed on the top of the flat ridge of the screw, and the projection blocks an imaging light flux reflected at the top of the screw and guided toward the film surface, and the imaging light flux enters the film surface. A photographing lens barrel for a camera, characterized in that the lens barrel is suppressed. 2. A photographic lens barrel of a camera having a female helicoid screw threaded around an optical axis of a photographic lens and exposed to a photographic light beam incident on the photographic lens, wherein the female helicoid is provided. The bottom of the screw is inclined with respect to the optical axis of the photographing lens, and the inclination suppresses a photographing light flux reflected at the bottom from entering at least onto a film surface. Shooting lens barrel. 3. A photographic lens barrel of a camera having a female helicoid screw threaded around an optical axis of the photographic lens and exposed to a photographic light beam incident on the photographic lens, wherein the female helicoid is provided. At least one concave portion is formed so that the flat portion does not remain at the top of the flat ridge of the screw, and the concave portion suppresses at least the photographing light flux reflected by the concave portion from entering the film surface. A photographing lens barrel for a camera, characterized by having a special shape.