JPH0332042B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lens fixing device that prevents distortion from occurring in the lens.

Distortion may occur when the lens is fixed to a lens frame or the like, which may impair the quality of the image. In particular, if distortion occurs when fixing a lens having a reflective surface in a reflective telephoto lens, the distortion of the reflective surface will significantly impair image quality. Therefore, as a lens fixing method to reduce this distortion, a method has been adopted in which the lens is tightened and fixed with a presser ring via a rubber sheet. In other words, Figure 1 (the lower half is omitted because the structure is symmetrical with respect to the optical axis)
As shown in FIG. 2, the lens 10 is placed in the lens frame 1 with its side surface fitted into the fitting part 1a of the lens frame 1 and in contact with the insertion lens holding part 1b. Next, a rubber sheet 2 of approximately the same size as the lens diameter is placed on the peripheral edge of the lens, and the retainer ring 3 is tightened by screwing the screws formed on the retainer ring 3 into the screws formed on the lens frame 1, and the lens 10 is tightened. The lens is fixed in the lens frame by narrowing the lens between the holding part 1b and the holding ring 3. However, in this method, even if distortion can be prevented on one side of the rubber sheet 2, the lens on the other side directly contacts the lens frame and is directly subjected to the clamping force of the holding ring, thereby causing distortion. In addition, when using this method, tightening is performed using a torque driver to keep the tightening force constant, but depending on the precision of the retainer ring (deformation of the diameter of the screw or retainer ring), the lens may be kept within a certain distortion. It is impossible to securely fix it with a torque screwdriver. For this reason, each assembled lens had to be inspected for distortion using an interferometer.

The present invention has been made in order to eliminate the above-mentioned conventional drawbacks, and a gap is provided between the peripheral edge of at least one surface of the lens and a lens holding member such as a lens frame or a holding ring, and silicone rubber is applied to this gap. The present invention provides a lens fixing device that fixes a lens by injecting and solidifying such a soft filler.

The details of the lens fixing device of the present invention will be explained below based on the illustrated embodiments. FIG. 2 is a diagram showing a first embodiment of the present invention, in which reference numeral 11 denotes a lens frame having a flange 11' at the tip provided with a silicone rubber injection port 11a, and 12 a flange 1 of the lens frame 11.
1' is a silicone rubber flow prevention ring (preferably made of resin or the like and has good removability), which is screwed onto the screw formed at the tip of 1'; 13 is a holding ring; The lens 10 is arranged in the lens frame 11 having such a structure, and the holding ring 13 is screwed onto the lens frame 11 to fix the lens 10, and then the ring 12 is screwed onto the screw of the flange 11', thereby lightly holding the lens 10.
Keep it in the state shown. In this state, silicone rubber is injected from the silicone rubber injection port 11a to fill the void shown by A. After the injected silicone rubber has solidified, the ring 12 is removed from the lens frame and the lens is fixed to the lens frame 11 using the holding ring 13 and the silicone rubber.

According to the above embodiment, the ring 12 and the presser ring 13
Since the lens is held in the correct state by the lens and then fixed with silicone rubber, the lens is held correctly in the mirror frame. In addition, even if a frame forms on the lens by tightening the presser ring 13 strongly in order to properly and securely fix the lens to the frame, distortion of the lens will be eliminated by removing the ring 12 after the silicone rubber has solidified. As shown in the figure, by scraping off the portion 10a of the lens 10 (a V-groove may be formed), the silicone rubber flows into this portion as well, thereby ensuring the connection between the lens and the lens frame.

FIG. 3 shows another second embodiment in which the lens frame is composed of two parts. In other words, reference numeral 15 denotes a first lens frame, and a holding portion 16 is provided that protrudes from the inner surface of the first lens frame. Reference numeral 17 denotes a second lens frame having a flange 17' at its tip provided with a silicone rubber injection port 17a. In this embodiment, the lens 10 is placed on the first lens frame 15 as shown, and then the second lens frame 17 is fixed with screws 18. At this time, the second
A ring-shaped sponge 19 is placed in a recess 17b formed at the tip of the flange 17' of the lens frame 17, and fixed so that the tip of the sponge 19 lightly touches the lens. Thereafter, silicone rubber is injected into the gap B through the silicone rubber injection port 17a and fixed.

In this embodiment, as in the first embodiment, the lens can be fixed without distortion.

In the case of this second embodiment, as in the first embodiment, the flange 17' of the second lens frame 17 is formed with a thread at its tip, and a ring for preventing silicone rubber from flowing is screwed into the flange 17'. May be used. In addition, the flange 11' of the lens frame 11 in the first embodiment may have a structure in which a ring-shaped member made of a soft material such as sponge rubber is attached as in the second embodiment, instead of using the silicone rubber flow prevention ring. Good too.

Next, FIG. 4 shows a third embodiment, in which a part of the lens 10 is removed as shown by 10b and the holding ring 13 is attached to the lens frame 20. It is made so that it does not hit directly.

In this third embodiment, the lens 10 is inserted into the lens frame 20, silicone rubber is injected into the gap C, and after it has solidified, the holding ring 13 is screwed in to fix the lens.

As explained above, in the present invention, a gap is provided between the lens and the lens frame, and silicone rubber is injected into the gap to fix the lens. Therefore, the lens can be fixed without distortion. .

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional lens fixing device, and FIGS. 2 to 4 are sectional views of each embodiment of the present invention. 10...lens, 11, 15, 17, 20...
Lens frame, 11', 17'...flange, 12...silicone rubber flow prevention ring, 13...pressing ring.

Claims (1)

[Scope of Claims] 1. A lens fixing device for fixing a lens to a lens frame, comprising: a flange having an inner diameter smaller than the outer diameter of the lens, provided at the tip of the lens frame and extending inward; and a flange having an inner diameter smaller than the outer diameter of the lens; at least one lens surface of the flange, and a flexible ring that extends in the optical axis direction from near the tip of the flange and is detachably attached or fixed to the flange, and that is detachably attached or fixed to the flange;
A soft filler such as silicone rubber is injected into the gap formed by the flange, lens surface, and ring and solidified to form a thick layer of soft material between the lens surface and the flange, and the lens is formed using this soft material. A lens fixing device characterized by being fixed to a mirror frame.