JPH04237006A - Lens focus lock device - Google Patents

Abstract

PURPOSE:To surely fix an external and an intermediate lens barrel in simple structure without the outward movement of the intermediate lens barrel in a focus lock state, and optical axis deviation and focus deviation accompanying it by fixing the external lens barrel and intermediate lens barrel indirectly across an elastically deformable ring. CONSTITUTION:On the outer peripheral wall surface of the intermediate lens barrel 2, the elastically deformable ring 3 which has a tapered inner peripheral part arranged so as to fit into the guide hole of the external lens barrel 1, a wedgelike pusher 4 which has a tapered outer peripheral part matching the tapered part and is arranged in the ring 3, and a stepped operation lever 5 which is implanted in the outer peripheral wall part of the intermediate lens barrel 2 so as to hole the small-diameter part of the pusher 4 are provided. Then the pusher 4 is pressed against the ring 3 with the operation lever 5 to expand the ring 3 outward by the wedge of the pusher 4 and the ring 3 is pressed against the inner wall of the guide hole of the external lens barrel 1 to fix the external lens barrel 1 and intermediate lens barrel 2.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus lock device for a projection lens used in a projection television or the like.

0002

2. Description of the Related Art In recent years, the need for large screens has increased, and the demand for projection televisions that enlarge and project images from a cathode ray tube (CRT) onto a screen using a projection lens has increased rapidly. In this projection television, lens focus adjustment is necessary in order to form a clear image of the CRT image through the projection lens onto the screen at a predetermined position. Must be securely fixed.

An example of a conventional lens focus lock device will be described below with reference to the drawings.

FIG. 3 shows the configuration of a conventional lens focus lock device. (Figure 3), 1
is an outer lens barrel having first and second guide holes 1A and 1B at symmetrical positions with respect to the optical axis on the outer peripheral wall, and the first and second guide holes 1
A and 1B are provided obliquely to the optical axis. 2 is a rotatable middle barrel that slides inside the outer barrel 1 in the optical axis direction;
Reference numeral 5 designates a stepped operating lever that is embedded in a screw 2A provided on the outer peripheral wall of the middle lens barrel 2 so as to fit into the first and second guide holes 1A and 1B.

[0005] The operation of the lens focus lock device constructed as described above will be explained below using (FIGS. 3 and 4).

First, as shown in FIG. 3, to adjust the focus, loosen the operating lever 5 and slide it along the guide holes 1A and 1B to adjust the focus. Adjustment is made by moving the barrel 2 back and forth in the optical axis direction with respect to the outer lens barrel 1.

Next, as shown in FIG. 4, when the focus adjustment is completed, tighten the operating lever 5, pull the middle lens barrel 2 using the head of the operating lever 5 as a fulcrum, and connect the operating lever 5 and the middle lens. The outer barrel 1 is held between the tubes 2 and the outer barrel 1 and the middle barrel 2 are fixed.

[0008]

[Problems to be Solved by the Invention] However, with the above configuration, when the operation lever is tightened to lock the focus after adjusting the lens focus, the inner barrel is pulled outward and becomes attached to the outer barrel. The lens moves by the amount of sliding clearance, causing a slight deviation of the optical axis, resulting in a tilt of the image plane and a focus shift.

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a focus locking device that is free from optical axis deviation and focus deviation during focus locking.

0010

[Means for Solving the Problems] In order to solve the above problems, the lens focus lock device of the present invention is arranged on the outer peripheral wall surface of the middle lens barrel so as to fit into the guide hole of the outer lens barrel. an elastically deformable ring having a tapered inner circumferential portion; a wedge-shaped pusher having an outer circumferential portion having a taper that matches the taper; and a wedge-shaped pusher disposed inside the ring; A stepped operation lever is provided on the outer peripheral wall of the middle lens barrel.

[0011]

[Operation] With the above-described structure, the present invention indirectly fixes the outer barrel and the middle barrel through an elastically deformable ring, thereby preventing the inner barrel from moving outward when the focus is locked. This eliminates the optical axis shift and focus shift associated with this, and also enables reliable fixing with a simple structure.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS A lens focus locking device according to an embodiment of the present invention will be described below with reference to the drawings.

(FIG. 1) shows the configuration of a lens focus lock device in one embodiment of the present invention. In (Fig. 1), 1 is an outer lens barrel having first and second guide holes 1A and 1B at symmetrical positions with respect to the optical axis on the outer peripheral wall,
The first and second guide holes 1A and 1B are provided obliquely to the optical axis. 2 is a rotatable middle barrel that slides in the optical axis direction inside the outer barrel 1; 3 is fitted into the first and second guide holes 1A and 1B on the outer peripheral wall surface of the middle barrel 2; 4 is an elastically deformable urethane ring having an outwardly open taper on the inner circumference, and 4 has a taper on the outer circumference that matches the taper of the ring 3, and is arranged on the inside of the ring 3; The provided wedge-shaped pusher 5 is a screw 2 provided on the outer peripheral wall of the middle lens barrel 2 so as to hold the pusher 4 in the small diameter portion.
This is a stepped operation lever installed in A.

The operation of the lens focus lock device constructed as described above will be explained below with reference to FIGS. 1 and 2.

First, as shown in FIG. 1, during focus adjustment, the operating lever 5 is in a relaxed state and the ring 3 is fitted into the guide holes 1A and 1B in its normal shape. Focus adjustment is performed by sliding the operating lever 5 along the guide holes 1A and 1B while being guided by the ring 3 to move the middle lens barrel 2 back and forth in the optical axis direction relative to the outer lens barrel 1. Adjust.

Next, as shown in FIG. 2, when the focus adjustment is completed, tighten the operating lever 5, press the pusher 4 against the ring 3 with the head of the operating lever 5, and push the ring 3 with the taper of the pusher 4. By pressing the taper and expanding the urethane ring 3 outward, the guide holes 1A and 1B are opened.
The outer barrel 1 and the inner barrel 2 are fixed by pressing the ring 3 against the inner wall of the barrel. At this time, only one of them may be fixed.

As described above, according to this embodiment, by indirectly fixing the outer lens barrel and the middle lens barrel through the intervening elastically deformable ring, the middle lens barrel can move outward when the focus is locked. This prevents the optical axis from shifting and enables reliable fixing with a simple structure.

[0018]

As described above, the present invention provides an elastically deformable ring having a tapered inner circumferential portion, which is disposed on the outer circumferential wall of an intermediate barrel so as to fit into a guide hole of an outer barrel. , a wedge-shaped pusher with a taper on the outer periphery that matches the taper and arranged inside the ring, and a stepped-shaped operation on the outer periphery of the middle lens barrel so as to hold the pusher in the small diameter part. By providing a lever, pressing the pusher against the ring using the operating lever, expanding the ring outward with the taper of the pusher, and pressing the ring against the inner wall of the guide hole to fix the outer and inner barrels, the focus is locked. There is no optical axis deviation or focus deviation, and a simple structure with a symmetrical shape enables reliable focus locking.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a lens focus lock device according to an embodiment of the present invention.

[Figure 2] Cross-sectional view for explaining the operation of the same embodiment

[Figure 3
】Cross-sectional view of a conventional lens focus lock device

[Figure 4]
FIG. 2 is a cross-sectional view for explaining the operation of a conventional example.

[Explanation of symbols]

1 Outer lens barrel 2 Middle lens barrel 3 Ring 4 Pusher 5 Operation lever

Claims (3)

[Claims] Claim 1: An outer lens barrel having a guide hole in an outer peripheral wall;
A rotatable middle lens barrel that slides in the optical axis direction inside the outer lens barrel, and a tapered inner periphery disposed on the outer peripheral wall surface of the middle lens barrel so as to fit into the guide hole. A ring that can be elastically deformed, a wedge-shaped pusher that has a taper on the outer periphery that matches the taper, and a wedge-shaped pusher that is arranged inside the ring, and a wedge-shaped pusher that is attached to the outer peripheral wall of the middle lens barrel so as to hold the pusher in the small diameter part. The head of the operating lever presses the pusher against the ring, and the taper of the pusher expands the ring outward, thereby pressing the ring against the inner wall of the guide hole and removing it. A lens focus lock device characterized by fixing a lens barrel and a middle lens barrel. 2. The lens focus lock device according to claim 1, further comprising a spring provided between the pusher and the middle lens barrel. [Claim 3] The pusher and the operating lever are integrated,
2. The lens focus lock device according to claim 1, further comprising a ring held at a tapered portion of the stepped operation lever.