JP2801062B2 - Lens barrel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to, for example, a zoom cam ring rotatably held in a fixed lens barrel, and one or more zoom cam rings arranged inside the cam ring parallel to the optical axis. A first guide bar, a second guide bar separated from the guide bar and arranged inside the zoom cam ring in parallel to the optical axis similarly to the first guide bar, and The present invention relates to a lens barrel comprising a lens holding / moving frame which is movably fitted or fitted in a circumferential portion, and wherein the lens holding / moving frame moves in an optical axis direction when a zoom cam ring is operated. is there.

2. Description of the Related Art A lens barrel, in particular, a lens moving device moves a moving frame holding a variator or a compensator in an optical axis direction by being guided by a guide bar, and is generally shown in FIG. It is configured as follows. That is, moving frames 14 and 15 having 5a 'and 7a' are provided with sleeve portions fitted and penetrated in guide bars 8 and 9 held parallel to the optical axis in a fixed lens barrel, and provided at positions separated from the guide bars. Another guide bar 16
Is provided, and is fitted to the moving frame in a U-shaped groove for the purpose of preventing the vibration, and is held movably in parallel with the optical axis. Further, a zoom cam ring (not shown) rotatably held between the fixed barrel and the moving frame / guide bar is provided, and a cam roller fixed to the moving frame is provided in a cam groove of the zoom cam ring. In a normal four-lens type zoom lens fitted and provided, two groups of a variator for zooming and a compensator for correction are held by the moving frame, and the length of the sleeve portion of the moving frame In order to secure the guide bar, one guide bar fitted and penetrated with the sleeve portion is prepared for each one, but the guide bar for steadying is commonly used.

In normal use, the camera is used upright,
On the other hand, since the light sources such as the sun and electric lights are often located above the camera, the two light guides, which are frequently used, are arranged on the upper side of the upper light source where no ghost or flare is generated. For this reason, the guide bar 16 for preventing the steady movement is inevitably disposed below the lens.

These guide bars are coated with oil as a lubricant to guide the holding frames 14 and 15 accurately and smoothly, and are close to the luminous flux. Guide bar reflects light on its surface,
It often caused ghost flares.

[Problem to be Solved by the Invention] Therefore, a steady rest guide bar that prevents reflection has been proposed by Japanese Utility Model Laid-Open No. 58-16604. That is, as shown in FIG. 8, a guide bar has been proposed in which a number of cuts are formed in a surface facing the optical axis, and light is prevented from being reflected by the cuts.

However, since this guide bar requires a large number of cuts, it has the disadvantage of increasing the cost. Further, since the cross-sectional shape of the guide bar is substantially circular, the straightness is poor and the guide for steadying is required to have high accuracy. Not suitable as a bar,
Particularly, the guide bar is not suitable as a shape formed of a synthetic resin.

Accordingly, it is an object of the present invention to provide a lens moving device having a guide bar having a shape that prevents reflection and obtains straightness.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a second guide bar, which is generally located in an upright state and located on the lower side, having a cross section substantially inverted T It is formed so as to have a U shape or a substantially U shape.

[Function] Also according to the present invention, the moving frame holding, for example, a zoom lens or the like is smoothly guided by the guide bar. In particular, in the first aspect of the present invention, since the cross-sectional shape of the guide bar is substantially inverted T-shaped or substantially U-shaped, the area near the optical axis is small, and therefore, the harmful reflection surface is narrow, and the ghost light is reduced. The occurrence of flare and the like is reduced. Further, since the cross-sectional shape is substantially inverted T-shaped or substantially U-shaped, straightness can be easily obtained as compared with a circular shape, and the moving frame can be guided with high accuracy.

[Embodiment] In FIG. 1, reference numeral 1 denotes a fixed lens barrel, and 2 denotes a zoom cam ring, which is rotatably fitted into the fixed lens barrel 1. The zoom cam ring 2 is connected to the zoom ring 3 and rotates integrally therewith.

The variator 4 is held by a variator, that is, a lens holding / moving frame 5, and the compensator 6 is also held by a compensator holding / moving frame 7. The two holding / moving frames 5 and 7 are fitted and held by guide bars 8 and 9 at sleeve portions 5a and 7a, respectively, and are provided at the opposite sides of the optical axis with respect to the sleeve portions 5a and 7a. The portions 5b, 5b are fitted to a guide bar 10 having an inverted T-shaped cross section, and are guided to move in the optical axis direction. The cam followers 5c and 7c abut on the cam portions Za and Zb of the zoom cam ring 2 and are fixed to the holding / moving frames 5 and 7, respectively.

Therefore, when the zoom ring 3 is operated, the zoom cam ring 2 rotates integrally therewith, and the holding / moving frames 5,
Numeral 7 moves in a relative positional relationship in the optical axis direction to perform zooming.

As shown in FIGS. 2 and 3, the guide bar 10 has an inverted T-shape in cross section facing the optical axis. As described above, because of the inverted T shape, the area near the optical axis is small, and the amount of reflection is small. Further, since the cross section has a T-shape, the required accuracy as the guide member, that is, the straightness is guaranteed even if the guide member is formed of, for example, a synthetic resin. Of course, the strength is also guaranteed.

Further, as shown in FIG. 4, when a plurality of notches for antireflection are formed on the surfaces a, b, and c on the optical axis side, the antireflection effect is further enhanced.

Referring now to FIGS. 5 and 6, it can be seen that a second embodiment of the guide bar is shown. That is, according to the present embodiment, the guide bar 13 is formed of, for example, a synthetic resin so as to have a substantially U-shaped cross section concave toward the optical axis. If necessary, the inner surface is cut. Also in the present embodiment, as is clear from the figure, the area near the optical axis is reduced, so that a failure due to reflection hardly occurs. It is also clear that straightness accuracy is increased.

[Effects of the Invention] As described above in detail, according to the present invention, the second guide bar for guiding the lens holding and moving frame has a substantially inverted T-shaped or substantially U-shaped cross section facing the optical axis. Therefore, as compared with the conventional one having a circular cross-sectional shape, the cross-sectional modulus is large, the strength is large, and the effect of excellent straightness is exhibited. Moreover, since the area of the portion near the optical axis is small, the amount of harmful reflection of light is small.

[Brief description of the drawings]

1 to 6 are views showing an embodiment of the present invention. FIG. 1 is a cross-sectional view thereof, FIG. 2 is a perspective view of a zoom portion, FIG. 3 is an enlarged side view of a guide bar portion, and FIG. FIG. 5 is a perspective view of a guide bar, FIG. 5 is a perspective view of a zoom portion showing another embodiment, FIG. 6 is a partially enlarged side view thereof, FIG. 7 is a perspective view of a conventional zoom portion, and FIG. FIG. 3 is a perspective view of a guide bar. 1 ... fixed lens barrel, 2 ... zoom cam ring 5, 7 ... lens holding and moving frame 8, 9 ... (first) guide bar 10, 13 ... (second) guide bar

Claims (1)

(57) [Claims] 1. A first guide bar arranged parallel to the optical axis, a second guide bar spaced apart from the first guide bar and arranged parallel to the optical axis, and these guide bars are circular. A lens holding / moving frame that is fitted or fitted into the peripheral portion and guided to move in the optical axis direction, wherein the second guide bar has a substantially inverted T-shape or a substantially U-shaped cross section facing the optical axis. A lens barrel formed in a character shape.