JPS61193111A - Zoom lens - Google Patents

Abstract

PURPOSE:To prevent mechanical flare on an image forming plane by forming an installation surface at the side of the optical axis of a lens guide hole and providing a nonreflecting means on the installation surface CONSTITUTION:When the nonreflecting means 20 is set on the installation surface 19, incident light, for example, from above a lens barrel 1 is not reflected because of the nonreflecting means 20. Consequently, no excessive light reaches the image forming plane 24 formed by adjusting focal lengths of lenses 15 and 16 and no mechanical flare is generated. Then, when the nonreflecting means 20 is installed at a lubricating oil stopping means 21, lubricating oil applied over the outer peripheral surface of a lower lens guide ball 18 does not enter the nonreflecting means 20 because of the lubricating oil stopping means 21. The incident light is reflected because of the nonreflecting means 20 and no lubricating oil which reflects the incident light intensely does not enter the nonreflecting means 20, so that prevention against the mechanical flare is further secured. Then, there is lubricating oil present between contacting places between the lower lens guide ball 18 and insertion grooves 13 and 14, so the smoothness of the movement of lens moving frames 3 and 4 is maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a zoom lens, and more particularly to a zoom lens that prevents the occurrence of mechanical flare.

In general, zoom lenses used in consumer video cameras, etc. have multiple lenses arranged in a cylinder, and multiple lenses arranged parallel to the optical axis around the optical axis. Some lens guide poles are configured to be movably guided through a lens movement frame.

Conventionally, in this type of zoom lens, it is desirable that the lens guide pole be installed outside the lens barrel.
This configuration has the disadvantage that the outer diameter of the zoom lens becomes extremely large.

To avoid this drawback, the lens guide pole is usually installed within the lens barrel.

However, with a zoom lens in which the lens guide pole is located inside the lens barrel, jl! When, for example, strong sunlight enters the cylinder, the incident light is reflected on the optical axis side of the lens guide pole and becomes reflected light unrelated to the light containing object information directed to the image plane. This reflected light then reaches the normal imaging plane as extra light, causing so-called mechanical flare, which blurs the image.

Furthermore, if there is grease or the like as a lubricating oil on the lens guide ball, the above-mentioned incident light will be reflected even more intensely, and mechanical flare will increase.

Lens hoods are used to prevent this mechanical flare, but zoom lenses for video cameras and other devices have zoom ratios ranging from the standard 6x to several tens of times, making it difficult to take wide-angle shots. Although it is effective to prevent mechanical flare using a lens hood, the problem is that this effect is extremely small when shooting on the variable magnification side.

11 years old This invention was made in view of the above problems.

The purpose is to provide a zoom lens that prevents mechanical flare on the imaging plane.

In order to achieve the above-mentioned object, the present invention provides a lens guide system in which a plurality of lenses arranged in a lens barrel are arranged around an optical axis and parallel to the optical axis. A zoom lens movably guided by a ball via a lens moving frame, characterized in that an installation surface is formed on the optical axis side of the lens guide hole, and a non-reflection means is provided on this installation surface. It is.

Husband 1h The present invention will be explained below based on the drawings.

1 to 7 show a first embodiment of the present invention.

In the figure, l is the lens barrel of the zoom lens, inside which a variator lens moving frame 3 and a compensator lens moving frame 4 are installed for each lens along the optical axis 2 formed on the center line of the lens barrel l. The focal length can be adjusted. Each moving frame 3, 4 is formed into the same annular shape, and upper protruding parts 5, 6 and lower protruding parts 7, 8 are provided on the diameter thereof, and the upper protruding parts 5, 6 and the lower protruding part A lens attachment portion 9.10 is provided inside the lenses 7 and 8. The upper protrusions 5 and 6 are provided with insertion holes 11 and 12 for the upper lens guide ball 17, and the lower protrusions 7 and 8 are provided with insertion grooves 13 and 14 for the lower lens guide ball 18, respectively. The diameter of the holes 11, 12 and the widths of the insertion grooves 13, 14 are formed to be approximately the same. In addition, the lens mounting part 9
A variator lens 15 is attached to the lens mounting portion 10, and a compensator lens 16 is attached to the lens attachment portion 10, respectively.

The upper and lower lens guide balls 17 and 18 are both made of metal such as aluminum and have a round bar shape, and are aligned with the optical axis 2.
A plurality of lenses are arranged in parallel with each other and are attached to the lens barrel 1 by attachment means (not shown).

Further, the outer surface of each lens guide ball 17, 18 is coated with lubricating oil such as grease, and the insertion holes 11, 12
and smooth contact with the insertion grooves 13 and 14.

Here, an installation surface 19 is provided on the optical axis 2 side of the lower lens guide ball 18. The installation surface 19 can take various forms, but here the lower lens guide ball 1
8 is formed as a V-shaped groove along the longitudinal direction, and a non-reflection means 20 that does not reflect incident light is provided on the upper surface of the groove. For the non-reflective hand @ 20, the upper surface of the installation surface 19 may be treated with a matte finish to prevent the reflection of incident light, or may be flocked or coated with matte paint (both of which are not shown).
) prevents the reflection of incident light and prevents unnecessary light that does not carry object information from being guided to the imaging plane, thereby preventing the occurrence of mechanical flare.

In this way, the lower lens guide ball 18 provided with the anti-reflection means 20 is connected to the variator lens moving frame 3. Insertion groove 1 provided in lower protruding parts 7 and 8 of compensator lens moving frame 4
3.14, through each lens moving frame 3, 4 in cooperation with the upper lens guide ball 17, each lens 15.1
6 in a movable manner. Also,
The aforementioned anti-reflection means 20 can be provided not only on the installation surface 19 but also on the lubricating oil blocking means 21, for example. The lubricating oil blocking means 21 prevents lubricating oil applied to the outer peripheral surface of the lower lens guide ball 18 from entering the installation surface 19.

For example, it is formed as a V-shaped plate using elastic synthetic resin, and is fixed to the installation surface 19 with adhesive or the like.

Since the width of this lubricating oil blocking means 21 is smaller than the outer diameter of the lower lens guide ball 1B, it does not become an obstacle when inserting the lower lens guide ball 18 into the insertion groove 13° 14, and the lens It does not become an obstacle when the movable frames 3 and 4 move on the lower lens guide pole 18. Also,
Even if the width of the lubricating oil blocking means 21 becomes larger than the diameter of the lower lens guide pole 18, its elasticity allows it to bend inward and not only pass through the insertion holes 13 and 14 of the lower lens guide pole 18, but also prevent the lens moving frame 3. There are no obstacles in the movement of 4.

In addition, 222 is a focus lens for focusing, 23
2 is a master lens of a relay system, and 24 is an imaging plane.

Next, the effect will be explained.

When the non-reflection means 20 of the installation surface 19 is installed, for example, incident light from the upper direction of the lens barrel 1 is not reflected by the non-reflection means 20. For this reason, each lens has 1 and 16 lenses.
No extra light reaches the normal imaging plane 24, which is formed by adjusting the focal length of 1, and mechanical flare does not occur. When the anti-reflection means 20 is installed in the lubricating oil blocking means 21, the lubricating oil applied to the outer peripheral surface of the lower lens guide pole 18 is prevented from entering the non-reflecting means 20 by the lubricating oil blocking means 21.

Therefore, not only is the incident light no longer reflected by the non-reflecting means 20, but also the lubricating oil that strongly reflects the incident light does not enter the non-reflecting means 20, so that mechanical flare can be prevented even more reliably.

Moreover, the lower lens guide ball 1B and the insertion groove 13°14
Since lubricating oil is present at the contact points with the lenses, the smooth movement of the lens moving frames 3 and 4 is maintained.

8 and 9 show a second embodiment of the present invention, in which the installation surface 30 is designed to facilitate processing of the constituent members.
It is formed into a band shape, such as a round bar cut parallel to the axis, and the anti-reflection means 20 is provided on this installation surface 30. Further, when preventing lubricating oil from entering the non-reflecting means 20, the non-reflecting means 20 is provided on a lubricating oil preventing means 31 provided on the installation surface 30. The lubricating oil blocking means 31 is formed as an elongated rectangular plate made of synthetic resin, for example, and has a width smaller than the diameter of the lower lens guide ball 18 . Therefore, it is easy to process, and the installation surface 30
It also becomes easier to adhere to. There is no problem in not only the insertion of the lower lens guide pole 18 into the insertion groove 13, 14 but also the movement of each lens moving frame 3, 4.

Further, FIGS. 10 and 11 show a third embodiment of the present invention. In this embodiment, the lubricating oil blocking means 32 is constructed as follows to facilitate machining.

That is, in the lower lens guide pole 18 having the installation surface 19 formed as a V-shaped groove, elongated grooves are formed at positions spaced apart from both side edges of the installation surface 19 and parallel to the edges. Also, in the case of the lower lens guide ball 18 having the strip-shaped installation surface 30, the lubricating oil blocking means 32
are formed as similar grooves. In this way, the lubricating oil applied to the outer periphery of the lens guide pole 18 is introduced into the lubricating oil blocking means 32 formed as a groove.
Lubricating oil does not enter the non-reflective means 20, and
The lubricating oil blocking means 32 can be easily machined, and the number of constituent members can be reduced.

In the above explanation, among the multiple lens guide poles, we have talked about the lower guide pole, which is the most frequent and has a problem with sunlight, which has a large effect.However, the guide pole is limited to this lens guide pole. It can also be applied to other poles.

As explained above, in the present invention, a plurality of lenses disposed in a lens barrel are arranged around an optical axis and parallel to the optical axis using a plurality of lens guide poles. In a zoom lens that is movably guided via a lens moving frame, on the optical axis side of the lens guide pole.

It is characterized by forming an installation surface and providing non-reflection means on the installation surface, so even if strong light such as sunlight enters the cylinder, this incident light will not be reflected by the non-reflection means. I won't. Therefore, it is possible to provide a zoom lens that always forms a normal image without allowing any extra light that would cause mechanical flare to reach the imaging surface.

[Brief explanation of the drawing]

1 to 7 show a first embodiment of the present invention, in which FIG. 1 is a side view of the lens barrel, FIG. 2 is a front view of the lens guide frame, and FIG. 3 is a front view of the lens guide frame.
The figure is a sectional view taken along the line ■-■ in Figure 2, Figure 4 is a perspective view of a lens guide pole with a non-reflection means provided on the installation surface of the V-shaped groove, and Figure 5 is the lens guide in Figure 4. A front view showing the insertion of the pole into the lens moving frame, FIG. 6 is a perspective view of the lens guide pole in which a non-reflective means is provided as the lubricant oil blocking means of the V raw plate, and FIG. 7 is the lens guide pole of FIG. 6. A front view showing insertion into the lens moving frame, FIGS. 8 and 9 show the second embodiment,
Fig. 8 is a front view of a lens guide pole with a non-reflective means provided on the strip-shaped installation surface, and Fig. 9 shows the insertion of the lens guide pole into the lens movement frame with a non-reflective means provided on the rectangular plate lubricant blocking means. FIGS. 10 and 11 show the third embodiment, and both are front views of a lens guide pole provided with a groove-shaped lubricating oil blocking means. 1... Lens barrel, 2... Optical axis. 3.4... Lens movement frame, 15.16... Lens. 17.18...Lens guide pole. 19.30... Installation surface, 20... Non-reflective means. 21.31.32...Lubricating oil blocking means. Toichihachi

Claims (2)

[Claims] (1) A plurality of lenses arranged in a lens barrel are movably guided via a lens movement frame by a plurality of lens guide poles arranged around an optical axis and parallel to the optical axis. A zoom lens, characterized in that a mounting surface is formed on the optical axis side of the lens guide pole, and a non-reflection means is provided on the mounting surface. (2) The zoom lens according to claim 1, wherein the lens guide pole is provided with lubricant oil blocking means for preventing lubricant oil from entering the non-reflective means on the installation surface.