JPS6184615A - Lens barrel - Google Patents

Abstract

PURPOSE:To hold lenses precisely even when a lens barrel molded not of resin is used by forming plural projection streaks on the internal wall of the lens barrel molded out of the resin material. CONSTITUTION:Projection streaks 8 are formed on the internal wall 7 at lens fitting positions circumferentially about a center axis O. The distance from the center axis O to the projection streaks 8 is set smaller than the radius of a lens 5 before the lens is inserted. Then, when the lens 5 is inserted as shown by an arrow B, part of the projection streak 8 is cut away by the outer diameter part of the lens 5. Consequently, the outer diameter part of the lens 5 is fitted to the projection screws 8 in contact and held in the lens barrel. Thus, the lens is held precisely even when the lens barrel molded out of resin is used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a lens barrel suitable for a zoom lens for a video camera and the like.

[Background of the invention]

As shown in FIG. 5, the zoom lens includes a zoom section 1, which is provided with a predetermined number of lenses. The master part 3 provided with a predetermined number of lenses and the mount 4 are connected to each other.

By the way, the zoom lens used in video cameras is
It is composed of 14 to 15 lenses and nearly 50 lens barrel parts, which makes the structure complicated and large, and it is very heavy and expensive. In particular, the large size and weight of a zoom lens poses a problem in that it reduces the operability of a video camera equipped with the zoom lens, and it has been desired to streamline the structure and reduce the weight of the zoom lens. Among the components of a zoom lens, the lens barrel parts are particularly
Since the number of parts is large and the quantity ratio is large compared to other parts, there was an urgent need to streamline the structure and make it lighter.

As a measure to meet these demands, it is conceivable to integrally mold the lens barrel parts, which were traditionally made from carved gold maple, from a resin material in order to reduce the number of parts per unit and reduce weight. , the accuracy required for high-end lenses such as zoom lenses cannot be obtained, and at present, the movable frames of pocket camera lens barrels and zoom lens lens barrels are made of resin at best. There is ℃.

By the way, even if there is such a problem, making the lens barrel of a zoom lens from resin is a very effective means from the viewpoint of reducing the number of parts and weight, and its realization is highly desired. but.

In particular, when the lens barrel (master barrel) 6 of the master part 3 is made of a resin molded product, the master lens group consisting of 7 to 8 lenses 5 held by this lens barrel 6 is a zoom lens. Since the lens holder in the lens barrel 6 has large variations in its inner diameter, the lens 5 rattles within the lens stitching part 6, making it impossible to obtain the required resolution performance.

This point will be explained in more detail by taking as an example the master part 3 consisting of seven lenses: 5 lenses in the front group with an outer diameter of about 30 mm and #2 rear lenses with an outer diameter of about 18 mm. .

In this master part 3, the maximum allowable amount of lens eccentricity is approximately 30μrnVc among lenses with an outer diameter of 3Qmm.
There are lenses that must be accommodated.

The inner diameter of the lens barrel 6 that holds such a lens can have an error from a specified value of 30 mm to a maximum of 60 ttm (30 μm x 2). Further, from the viewpoint of ease of inserting the lens into the lens barrel 6, it is common to allow a clearance of 30 μm in diameter between the lens barrel 6 and the lens. Therefore, the inner diameter of the lens barrel 6 for the above lens needs to be increased from the specified value of 30 mm to +30 μm to 60 μm. The above is a case where there is no error in the lens outer diameter, but in reality, the manufacturing error in the lens outer diameter is ±10μ.
m is the limit, and considering this point, the inner diameter of the lens section 6 is +30 μm to +50 μm from the above specified value.
Must be set within the range.

However, the error in the inner diameter of the lens barrel 6 was reduced to 20 μm (50 μm).
It would be extremely difficult to set it within the range of m - 30 μm), and even if it were possible, it would be difficult to produce a large number of high-precision lens barrels like the one above from one mold due to problems such as mold wear. I can't. Therefore, the master barrel in conventional zoom lenses is generally made of turned metal.

[Purpose of the invention]

An object of the present invention is to eliminate the drawbacks of the prior art described above and to provide a resin-molded lens barrel that allows a lens to be mounted with a high degree of bulk.

[Summary of the invention]

In order to achieve this purpose, the iPl of the present invention is provided integrally with a mantissa number of protruding stripes on the inner wall of the lens barrel along the circumference centered on the central axis of the lens barrel, and The feature is that the lens is held in a 5KL manner so that the lens is tightly fitted into the stripe.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 (al is a partial vertical cross-sectional view showing one embodiment of the lens barrel according to the present invention, and FIG. 1(b) is a dashed-double line A in FIG. 1(a)
- A' is a cross-sectional view along A', 5 is a lens, 7 is an inner wall, and 8 is a beam-like line.

In this embodiment, eight master barrels of a zoom lens are shown as an example. In FIG. 1(a), the inner wall 7 is provided with a protruding line 8 at the fifth position for attaching the lens. As shown in the figure (b), a plurality of protruding stripes 8 (three in the figure) are provided at equal intervals in the circumferential direction around the central axis 0, and the lens 5 is attached to these protruding stripes 8. They are tightly fitted and held together. - FIG. 2 is a perspective view showing a specific example of the protruding stripe 8, and shows the state before the lens is attached.

In this specific example, the protruding stripe 8 is elongated in the insertion direction (arrow B) of the lens to be attached, and has a strip shape with an inclined side surface at least on the lens insertion port side, and the thickness of the protruding strip 8 is the same as that of the lens to be inserted. is set so that it hits all of the projected stripes 8 thrown. Therefore, before the lens is inserted, the distance 41 from the central axis 0 (FIG. 1(b)) to the protruding stripe 8 is smaller than the radius of the lens.

When the lens is inserted in the direction of arrow B, the lens 5 hits the inclined side surface of the protruding stripe 8, as shown in FIG.
By further pushing the lens 5 in, a portion of the protruding line 8 is scraped off by the outer diameter portion of the lens 5. In this way, the outer diameter portion of the lens 5 is tightly fitted into each of the protruding stripes 8.

It is held within the lens barrel.

The protruding stripes 8 are formed in a well-balanced manner with respect to each other in position, shape, and size. Therefore, when an inserted lens is pushed into the protruding stripes 8, all the protruding stripes 8 are well-balanced with each other. The lens can be installed with less than the allowable eccentricity.

Therefore, the thickness of the protruding stripes 8 is now 80 μm.

When manufacturing a lens barrel so that the width is 240 μm, the aforementioned outer diameter is 39 mm and the manufacturing error is +0 μm to +20 μm.
When attaching a µm lens, the inner diameter of this lens barrel must be adjusted so that the manufacturing error is at least +20 µm, since the clearance between the lens and the inner wall of the lens barrel must be 30 µm in diameter from the viewpoint of lens installation work. 50 ttm (30μm) than the specified value of 30mm for the lens.
+20 μm) must be large. In this case, the clearance kl diameter for a lens with a manufacturing error of +0 μm is 50 μm or more.

On the other hand, if the range in which the inner diameter of the lens barrel is larger than the specified value is 160 μm (80 μm x 2) or less, the above lens may hit all three protruding stripes 8, but there is a margin. The thickness is 130 μm or less. In other words, the inner diameter of the lens barrel is +50μm to +130μ than the specified value.
Increase within the range of m.

When the inner diameter of the lens barrel is set in this way, when no protruding stripes are provided as in the prior art, the maximum eccentricity of the lens is 65 μm (130 μm ÷ 2), which exceeds the lens holding tolerance specification (30 μm). If the number is more than doubled, the resolution performance will deteriorate significantly. In contrast, in the above embodiment, by forming each protruding stripe in a well-balanced manner,
It becomes possible to lock and hold the lens so that there is no backlash and the amount of eccentricity is within the allowable range. In addition, the manufacturing error in the inner diameter of the lens barrel is 80 tt m (13011
m-50 μm), which is sufficiently large compared to 20 μmK in the above-mentioned prior art, and this alone can ease the manufacturing precision of the lens barrel.

FIG. 4 is a perspective view of main parts showing another embodiment of the lens barrel according to the present invention, in which 9 is a stepped portion, 10 is an adhesive, and parts corresponding to those in FIG. 3 are designated by the same reference numerals. ing.

In this embodiment, a step 9 for regulating the position of the lens 5 in the optical axis direction is provided on the inner wall 7 of the lens barrel, and a protruding stripe 8 is provided along this step 9vC.

The lens 5 is inserted from the direction of arrow B, and by pushing the lens 5 into the hole 5 as explained in FIG.
Although a portion of the lens 5 is scraped off, the mounting position of the lens 5 is set by the contact of the lens 50 surface with the stepped portion 9.

Further, in order to prevent the lens 5 from falling off, the lens 5 is bonded to the workpiece-like stripe 8VC using an adhesive 10.

゛ This produces the same effect as this embodiment, but
Furthermore, the spacing ring conventionally used for holding and locking the lens is no longer necessary, resulting in further weight and cost reductions.

As described above, each lens is attached by providing three protruding stripes at each position, and by attaching each lens with an eccentric amount within an allowable range.

Note that for one lens installation, the number of protruding stripes provided at a position may of course be four or more, but if the structure of the lens barrel type is complicated or the number of protruding stripes is three or more, the lens Considering that there is not as much difference in the precision of mounting as shown in the left, it is preferable to set the number of protruding stripes to three, which is the minimum necessary number.

Furthermore, although the above embodiment has been described using the master barrel of a zoom lens as an example, the present invention is not limited to this.

〔Effect of the invention〕

As explained above, according to the present invention, even with variations in the inner diameter of the lens barrel due to resin molding, the wobble of the lens can be eliminated, and the amount of eccentricity of the lens can be set within an allowable range. It is possible to achieve high-precision lens holding comparable to that of a metal-milled lens barrel, and it is possible to reduce the number of parts, reduce weight, reduce costs, and achieve excellent optical performance. It is possible to provide a lens barrel with a wide range of functions.

[Brief explanation of drawings]

FIG. 1(a) is a partial vertical cross-sectional view showing an embodiment of a lens barrel according to the present invention, FIG. 1(b) is a cross-sectional view taken along the dashed double-dot line A-X in FIG. 1(a), FIG. 2 is a perspective view showing a specific example of a protruding stripe, FIG. 3 is a perspective view showing how the lens is mounted, and FIG. 4 is a perspective view showing another embodiment of the lens barrel according to the present invention. A perspective view, FIG. 5, is a configuration diagram showing an example of a zoom lens. 7...Inner wall, 8...Protruding streaks. Figure 1 (0) (b) Figure 2
Figure 3

Claims (1)

[Claims] A plurality of protruding stripes are integrally molded from a resin material in the circumferential direction around a central axis on the inner wall, and the distance from the central axis to the protruding stripes is made smaller than the lens radius. . A lens barrel, characterized in that the lens can be held by the protruding stripes.