JPS5819523Y2 - Lens frame device for cemented lenses - Google Patents

Description

[Detailed Description of the Invention] The present invention is a lens frame device for fixing a cemented lens, in which at least one lens in a group of cemented lenses has a larger outer diameter than the other lenses, to a lens barrel. This is related to the improvement of

For example, in the case of a photographic lens, as typified by a Gaussian lens, the negative lens of the inner cemented lens sandwiching the aperture blades is not arranged with its outer edge protruding toward the aperture blade. It happens often.

In such a case, if the distance between the outer edge of the negative lens and the diaphragm blades is widened, it is possible to fix the inner cemented lens to the lens barrel using a lens frame that sandwiches both ends of the cemented lens. If the distance is narrow, a special lens frame system must be used.

What is shown in FIGS. 1 and 2 is an example commonly used in the past in this case, but in the case of the example shown in FIG. 1, the small diameter lens L1, which is a negative lens, is not involved in fitting, Since the outer periphery of the large-diameter lens L2, which is a positive lens, is used as the fitting surface with the lens frame 1, a disadvantage of this holding method is that the lens falls due to the narrow fitting width. In this case, the disadvantage of this holding method is that a part of the outer periphery of the cemented lens must be removed.

Such problems do not simply occur between the cemented lens and the aperture blades, but also between the negative lens and other lenses, and are a common problem in various optical systems. .

The present invention was devised to solve this problem, and its novel feature is, as is clear from the embodiment of the present invention shown in FIG. The outer diameter of the small-diameter lens L1 is used to fit the cemented lens consisting of the above into the lens frame 1, and the peripheral edge of the large-diameter lens L2 is held in place to fix the cemented lens in the optical axis direction. be.

That is, in the lens frame device of the present invention, a fitting inner diameter 1a that fits with the outer diameter of the small diameter lens L1 is provided from one end of the lens frame 1, and the fitting width of the fitting inner hole is set so as to fit with the outer diameter of the small diameter lens L1. Since the width is less than the outer diameter, the lens frame 1 does not protrude beyond the small diameter lens L1, and the fitting width is sufficient for stability against lens collapse.
Following the fitting inner hole 1a, there is provided the fitting inner hole 1b, which has an inner diameter smaller than the outer diameter of the large diameter lens L2, so that the cemented lens can be easily inserted from the fitting inner hole 1b side. The cemented lens can be fixed in the optical axis direction by connecting the expanded end surface 1c of the connecting portion between the fitting inner hole 1a and the fitting inner hole 1b and the holding surface 2a of the holding member 2 fitted into the fitting inner hole. We are making sure that we can do it within the time it takes.

As is clear from the above, according to the present invention, the second
Stepping of the lens as shown in the figure eliminates the need for machining, and the width of the mating surface can be widened, increasing the right angle stability of the lens. Since the thickness of the lens can be reduced, excellent effects can be obtained, such as helping to make the lens system structure lighter, more compact, and lower in cost.

The present invention is most suitable for use when the small diameter lens L1 of the cemented lens is a negative lens and the large diameter lens L2 that fits within the lens frame 1 is a positive lens, as shown in the figure, but it is not limited thereto. A similar effect can be obtained in a cemented lens in which the outer diameter width of the small diameter lens is thicker than the outer diameter width of the large diameter lens.

Moreover, the small diameter lens L1 and the large diameter lens L2 do not necessarily need to be one lens.

The holding member 2 may be a threaded ring as shown in FIGS. 1 and 2, or may be a spacer ring that presses against the other hand and holds the large diameter lens as shown in FIG. 3.

Of course, the present invention is not limited to cameras.

[Brief explanation of the drawing]

1 and 2 are partial vertical sectional side views showing the main parts of a conventional lens frame device, and FIG. 3 is a partial vertical sectional side view showing the main parts of the lens frame device of the present invention. 1... Lens frame, 1a... Fitting inner hole,
1b: Fitting insertion hole, 1c: Expanded end surface,
2...Press member, 2a...Press surface, L
L...Small diameter lens, Ll...Large diameter lens.

Claims (1)

[Scope of utility model registration request] In a lens frame device for fixing a cemented lens, in which at least one lens in a group of cemented lenses has a larger outer diameter than the other lenses, to a lens barrel, the lens frame fits with the outer diameter of a small diameter lens. The fitting inner hole is provided from one end of the lens frame so that the fitting width is equal to or less than the outer diameter width of the small diameter lens,
Next to the fitting inner hole, a fitting inner hole is provided which opens to the other end of the lens frame and has an inner diameter smaller than the outer diameter of the large diameter lens, so that a fitting hole is provided at the connection part between the fitting inner hole and the fitting inner hole. A lens frame device for a cemented lens, wherein a presser member that clamps the peripheral edge of a large-diameter lens between an expanded end surface and a presser member is fitted into an insertion hole from the open side of the other end of the lens frame.