JPS63271307A - Lens barrel of camera - Google Patents

Abstract

PURPOSE:To provide a lens barrel having a focusing mechanism which is small in size, light in weight and low in cost by providing a spring mechanism which energizes and releases an energizing spring force to and from a focusing lens barrel cooperatively with rotation of a lens barrel for focus changing. CONSTITUTION:The energizing spring 9 is in the state of 9T shown in the figure where the spring does not engage to a cam face 4d in a long focus state (a change lens is held positioned on the optical axis for photographing). On the other hand, the spring 9 attains the state of 9W shown in the figure where the spring engages to the cam face 4d in the short focal state in which the change lens 1 is retreated off the optical axis of photographing. The backward energizing force acts on the focusing lens barrel 4 in this state. A shaft 4b provided as a part of the lens barrel 4 is freely fitted into a square hole 10d formed to a stopper plate 10. This shaft 4b is confined to the length l shown in the figure in the moving range by the hole 10d, by which the moving limit of the focusing lens 2 is controlled. The focusing mechanism which is small in size, light in weight and low in cost is thereby obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to a lens barrel of a camera, and more particularly to an automatic focus switching device, particularly the configuration of its drive mechanism.

(Background of the Invention) Conventionally, a focus switching device in a lens barrel drives a focusing lens group (hereinafter referred to as a focusing lens) in the direction of the photographing optical axis using a mechanism such as a helicoid or a cam. It is normal that In addition, the lens group for switching the focus between long focus and short focus (hereinafter referred to as focus switching lens) is rotatably supported on a shaft eccentrically arranged with respect to the photographing optical axis. By rotating it, you can select whether to position the focus switching lens above the photographic light glaze or to retract it off the photographic optical axis.

However, with lens barrels that have such a focusing mechanism or focus switching mechanism, it is usually necessary to provide a mechanism that drives the focusing lens a predetermined distance necessary for focusing after initial focusing (tracking adjustment). However, the problem is that the structure becomes complicated.

(Object of the Invention) The present invention has been made from the above-mentioned viewpoints, and its purpose is to eliminate the disadvantages of the conventional focus switching device which has a complicated structure as described above, and to provide a compact, lightweight and An object of the present invention is to provide a lens barrel having an inexpensive focusing mechanism.

(Summary of the Invention) The camera lens barrel according to the present invention, which has been made to achieve the above object, has the following features: A focusing lens group is provided to be movable in the optical axis direction, and a focusing lens group is provided to be movable into and out of a position on the photographing optical axis by rotation about an axis eccentrically arranged with respect to the photographing optical axis. In a lens barrel of a camera equipped with a focus switching lens group, when the focus switching lens group is retracted outside the photographing optical axis, a spring force is applied to suppress and engage the focusing lens group to a fixed focus position. A spring is provided to bias the focus switching lens group, and the spring releases the pressing engagement spring force in conjunction with a switching operation that moves the focus switching lens group from a retracted position outside the photographing optical axis to a position on the photographing optical axis. A movement range limiting means is provided between the focusing lens group and the lens barrel body for determining a movement range of the focusing lens group in the photographing optical axis direction, and the lens barrel body further includes: The present invention is configured to include a driving means for moving the focusing lens group within the limited movement range via a gear mechanism.

(Example of the invention) The present invention will be described below based on embodiments shown in the drawings.

1 to 5 show an embodiment of the present invention, in which FIG. 1 is a longitudinal sectional front view of a lens barrel, FIG. 2 is a partially sectional side view of FIG. 1, and FIG. 5 to 5 are partial cross-sectional views of the lens barrel shown in FIG. 1, respectively.

In these figures, 1 is a focus switching lens, 2 is a focusing lens, and 3 is a lens barrel for the focus switching lens 1 (
(hereinafter referred to as a switching lens barrel), 4 is the above-mentioned focusing lens 2
(hereinafter referred to as focusing lens barrel),
5 indicates the lens barrel body.

Reference numeral 6 indicates two aperture blades, and reference numeral ``f'' indicates an axis extending in the front-rear direction along the side of the focusing lens 2 inside the lens barrel body 5. ), and is provided to form a pivot shaft that supports the focus switching lens 1 so that it can be rotated and switched from a retracted position outside the photographing optical axis to a position on the photographing optical axis.

Note that the focusing lens 2 is supported by the lens barrel body 5 by inserting a recess 4a formed in a part of the lens barrel portion into a protrusion 5 of the lens barrel body.
a in a slidable manner in the direction of the photographing optical axis, and a radial arm 4C is extended from the edge opposite to the recess 4a, and its distal end portion is fitted to the shaft 7 to support it. I'm letting you do it.

Further, the focus switching lens 1 is supported by the lens barrel body 5 by rotatably supporting the tip of a radial arm 3a extending in the radial direction from the lens barrel portion of the switching lens barrel 3 on a shaft 7. This is achieved by stably engaging the switching lens barrel 3 with the stopper portions 5b, 5c of the lens barrel body 5 using springs that do not move.

Here, in the state shown by the solid line in FIG. 2 (that is, when the switching lens 1 is retracted off the photographic optical axis), the entire lens barrel is a short distance that is focused only by the focusing lens 2. It is in a focused state. FIGS. 2 to 5 illustrate this state.

Basically, the entire lens barrel where the switching lens 1 is retracted outside the photographing optical axis is the entire distance to the subject.
The lens is designed to focus in this state.

Also, the state shown by the broken line in Fig. 2 (that is, the state where the switching lens barrel 3 is positioned on the photographing optical axis)
In this case, the entire lens barrel is in a long focal state. In the case of this long focus state, the imaging focus becomes shallow, so it is not possible to focus on the entire distance to the subject, so an automatic focusing device is used to adjust the distance to the subject.
The focusing lens 2 can be switched between the infinity side and the close range side depending on whether the distance is greater than or less than a predetermined distance value (threshold value). Note that the configuration and operation of this automatic focusing device will be further described later.

8 is an E-ring that prevents the shaft 7 from being removed from the lens barrel body.

Reference numeral 9 denotes a biasing spring that is integrally assembled to the switching lens barrel 3, and changes the switching lens barrel from a long focus state (a state in which the switching lens 1 is on the photographing optical axis) to a short focus state. It is provided so as to engage with the tip of the focusing lens barrel 4 and press it rearward when the switch is switched.

Reference numeral 10 denotes a stopper plate, which allows for slight positional adjustment in the photographing optical axis direction on the color of the lens barrel body, but is fixedly supported after adjustment, and in this fixed state, the focusing lens barrel 4 is not photographed. It has a function of limiting the movement range in the optical axis direction.

Numeral 11 is a fixing screw implanted in the lens barrel body, and is used to fix the stopper plate 10 onto the lens barrel body.

As described above, the stopper plate 10 limits the movable range of the focusing lens barrel 4, and the biasing spring 9 presses the focusing lens barrel rearward within the limited range during short focus to bring it to its limit position. By keeping the engagement stationary and releasing the pressure of the biasing spring 9 on the focusing lens barrel 4 during long focusing, the automatic focusing device can focus between the focusing positions on the infinity side and the close side. It makes it possible to move. Note that the focusing positions on the infinity side and on the close side at the time of long focal length are given as both limit positions of the range limited by the stopper plate 10.

Next, a mechanism for moving the focusing lens 2 between infinity and close focusing positions during long focal length will be described.

Reference numeral 12 denotes a rotation shaft assembled to the focusing lens barrel 4, and the worm wheel 13 is rotatably supported by the rotation shaft 12, and is removed by a flat washer 14 and a wave washer 15. It's stopped. 16 is a worm gear assembled at a predetermined position on the lens barrel body 5;
A worm gear mechanism is configured by meshing with the worm wheel 13, and rotational force is applied from the reduction gearless motor 17.

The speed reducer non-motor 17 is driven by a signal from an automatic focus control circuit (not shown) when a drive motor (also not shown) is driven. And in this example, the first
In order to switch the focusing lens 2 to the close-up side, for example, during the long focal length shown in the figure, the worm gear mechanism is rotated. In this example, the drive motor that rotates the worm gear mechanism is driven only for a predetermined period of several seconds by a control circuit (not shown) and then stopped. It is configured to allow slippage due to the action. Allowing for this slip is effective in preventing excessive force from acting on the mechanism, and by using a worm gear mechanism, the drive motor for moving the focusing lens barrel can be attached to the lens barrel body. Another advantage is that it can be provided in a fixed manner.

With the above configuration, when the switching lens 1 is rotated and switched from the state where the switching lens 1 is retracted outside the tIl shadow optical axis (short focus state) to the photographing optical axis, the focusing lens 2 is The pressing force of the biasing spring 9 is released.

Next, when a signal to move the focusing lens 2 to the close side is output from the control circuit linked to the distance measuring device etc. of the camera body, this signal causes the drive motor linked to the ohmic gear mechanism to be activated. When driven, the focusing lens barrel 4 is moved to the front limit position (closest focusing position: see reference numeral 4b' in FIG. 4) within a range limited by the stopper 10, and conversely to the infinity side. If a signal to move to the position is output, reverse the above operation to move to the rear limit position (
The focus position is returned to the infinity side (see reference numeral 4b in FIG. 4).

In the above example, the spring force of the biasing spring 9 is applied to the focusing lens barrel 4 by switching the rotation of the switching lens barrel 3 to retract the switching lens 1 outside the photographing optical axis. The specific configuration is such that a biasing spring is applied to the opposing surface of the focusing lens barrel 4 that faces the biasing spring 9 integrated into the switching lens barrel 3 by a rotation switching operation of the switching lens barrel 3. This is achieved by forming an inclined cam surface 4d that separates and engages with each other.

That is, the long focus state (switching lens 1
is located on the photographing optical axis), the biasing spring 9 is in the state 9T shown in the figure in which it does not engage with the cam surface 4d, and on the other hand, the switching lens 1 is in a short focus state in which it is retracted outside the photographing optical axis. (See FIG. 2), the biasing spring 9 is engaged with the cam surface 4d in the state 9W shown in the figure, and a backward biasing spring force acts on the focusing lens barrel 4. It is.

Next, a detailed explanation will be given of the specific configuration of this example in which the movement limit range of the focusing lens barrel 4 provided by the stopper plate 10 is specified.

The shape of the stopper plate 10 in this example and the manner in which it is assembled to the lens barrel main body 5 are shown in FIG.
protrudes from the lens barrel body 5, and engages the grooves 10c, 10c of the stopper plate 10, and furthermore, these pair of grooves 10c
, 10c is inserted into the long hole 10b, and the fixing screw 11 is screwed into the threaded hole of the lens barrel body 5, thereby fixing the stopper plate IO.

And in the square hole 10d formed in this stopper plate lO,
The shaft 4b provided as a part of the focusing lens barrel 4 is fitted loosely, and the movement range of the shaft 4b is limited to the length shown in the figure 1 by the square hole 10d, so that the focusing lens 2 described above can be This sets the limits of movement. In FIG. 4, the axis indicated by reference numeral 4b indicates the position of the focusing lens barrel 4 at short focal length, and the position at which focus is achieved on the infinity side at long focal length, and the axis indicated by reference numeral 4b' The state shown by indicates the position in focus on the close side during long focal length.

The stopper plate 10 of this example has a structure in which the above-mentioned pair of protrusions (bins) 5f, 5f of the lens barrel body engage with the grooves 10c, 10c of the stopper plate 10, and loose fitting between the elongated hole 10b and the fixing screw 11. Due to this relationship, it is possible to slightly adjust the position in the direction of the photographing optical axis with the fixing screw 11 loosened, and a tracking adjustment structure is also provided to make this position adjustment. be. That is, the stopper plate 10 has a round hole 10a for tracking adjustment.
is formed as shown in FIG. 4, and a groove 5e (orthogonal to the photographing optical axis) formed on the surface 5d of the lens barrel body 5 extends outward through the round hole 10a. Then, an eccentric pin (not shown) (tracking adjustment jig) is fitted into this groove 5e, and the stopper plate 10 is adjusted in position in the photographing optical axis direction while rotating eccentrically, and after adjustment, the fixing screw 11 is screwed. By fixing the focus, extremely simple tracking adjustment is possible.

Moreover, during this tracking adjustment, the worm gear mechanism described above is allowed to slip due to the action of the washer 15, so that no undue force is applied to the mechanism, and the drive motor can be fixedly mounted on the lens barrel body. You also get benefits.

(Effects of the Invention) As described above, the lens barrel according to the present invention applies a biasing spring force to the focusing lens barrel in conjunction with the rotation of the focus switching lens barrel.

It has a spring mechanism that can be released, thereby making it possible to obtain a convenient support state for the lens barrel both at short focal length and long focal length. As is clear from the explanation, a camera with a lens barrel with this configuration has the advantage that the three functions of focus switching, tracking adjustment, and focusing drive can be achieved with a single relatively simple structure. Its usefulness is extremely great, as it is effective for providing a camera having a focus switching lens mechanism that is small, lightweight, and inexpensive.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional front view showing an example of an overview of the configuration of a lens barrel according to the present invention, and FIG. 2 is a side view including a partial cross section of the same.
Figure 3 is an enlarged view of the biasing spring assembly; Figure 4 is a diagram to explain the shape and installation of the stopper plate; and Figure 5 is a diagram to explain the focusing mechanism. be. 1... Focus switching lens 2... Focusing lens 3...
・Switchable lens barrel 4...Focusing lens barrel 4a...
・Recess 4b...Axis 4c...Radial arm 5...List barrel body 5a...Protrusions 5b, 5c
...Stopper portion 5e...Groove 5f...Protrusion 6...Aperture 7...Shaft 8...E-ring 9...Biasing hole 10...Stopper
10a: Round hole 10b: Long hole 10
C: Groove 10d: Square hole 11... Fixing screw 12... Rotating shaft 13.
... Worm wheel 14 ... Plain washer 15 ... Wave washer 16 ... Ohm gear 17 ... Reduction gearless motor Fig. 1 Fig. 2

Claims (1)

[Claims] A lens barrel body of the camera, a focusing lens group disposed inside the lens barrel body and movable in the direction of the photographing optical axis;
In a lens barrel of a camera, the lens barrel of a camera is provided with a focus switching lens group that is provided so as to be movable into and out of a position on the photographing optical axis by rotation about an axis eccentrically arranged with respect to the photographing optical axis,
A spring is provided that applies a spring force to press and engage the focusing lens group to a fixed focus position when the focus switching lens group is retracted outside the photographing optical axis, and the spring is used for the focus switching. The pressing engagement spring force is released in conjunction with the switching operation of moving the focusing lens group from a retracted position outside the photographing optical axis to positioning it on the photographing optical axis, and between the focusing lens group and the lens barrel body. is provided with a movement range limiting means for determining the movement range of the focusing lens group in the photographing optical axis direction, and further, the lens barrel body is provided with movement range limiting means for determining the movement range of the focusing lens group in the photographing optical axis direction, and further, the focusing lens group is connected to the limited movement range through a gear mechanism. A camera lens barrel characterized by being provided with a driving means for moving within a movement range.