JPH09329733A - Multi-focus magnification switching lens barrel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute variable power operation and focusing operation at respective variable power positions by an identical driving source and to make a camera compact and inexpensive by providing a fixed barrel with a guide means for executing the focusing operation by guiding a second lens unit according to the turning action of a rotating barrel as for the multi-focus magnification switching lens barrel of the camera executing a step-zooming action. SOLUTION: A fixed barrel 2 is provided with a cam groove 14 for focusing adjustment having an inflection point for a second moving barrel 5 for holding a rear-group lens 7 and a guide groove 13 guiding a first moving barrel 4. The rotating barrel 3 is provided with cam grooves for variable power 11 and 12 respectively guiding the first and the second barrels 4 and 5. By the groove 12 of the barrel 3 and the groove 14 of the barrel 2, the second barrel 5 is guided. Then, the variable power operation and the focusing operation are simultaneously executed by the rotating operation of the barrel 3 by one driving force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multifocal magnification switching lens barrel, and more particularly to a multifocal magnification switching of a camera having a step zoom mechanism capable of selecting a plurality of focal lengths between a wide position and a tele position. Regarding the lens barrel.

[0002]

2. Description of the Related Art There is known a camera having a zoom mechanism capable of continuously changing a focal length of a photographing lens between a short focal length position (wide position) and a long focal length position (tele position). There is. In this type of camera, the lens barrel includes a front lens group and a rear lens group, and the front lens group is held by a movable barrel that moves in the optical axis direction with respect to a fixed barrel, while The group lens moves in the optical axis direction while maintaining a predetermined optical positional relationship with the front group lens. Thereby, the magnification of the taking lens is changed.

When the shutter button is half-depressed in the photographing lens thus adjusted in magnification, the distance from the camera to the object is measured by the automatic focusing mechanism, and the focus adjustment is performed based on the measurement result. It has become. In this case, conventionally, during zooming, the front lens group and the rear lens group are moved linearly by a driving source for zooming to perform zooming, and when focusing, the front lens group is fixed and only the rear lens group is fixed. It is known that another focus adjustment drive source moves in the optical axis direction to perform focus adjustment.

[0004]

However, in the above-mentioned structure, a separate drive source and drive system are required for zooming and focus adjustment, which increases the size of the camera and increases its cost. There was a problem. The present invention has been made in view of such circumstances, and an object thereof is to provide a multifocal magnification switching lens barrel that performs zooming and focus adjustment by the same drive source.

[0005]

A multifocal magnification switching lens barrel according to the present invention is provided with first and second lens units arranged on the front and rear of the optical axis and rotatable about the optical axis. A rotary cylinder having a first guide portion for moving each of the two lens units in accordance with the rotation, and a rotary cylinder provided inside or outside the rotary cylinder and moving in accordance with the rotation of the rotary cylinder. A fixed barrel having a second guide portion for guiding the two lens units in the optical axis direction,
One of the first and second guide portions is configured to respectively guide the two lens units and perform magnification switching according to the rotation of the rotary cylinder. The other one of the guide portions is configured to guide at least one of the two lens units and adjust the focus of the entire system according to the rotation of the rotary cylinder. It is a thing. Further, it is preferable that the first and second guide portions are configured to act on at least one of the lens units when the other is inactive.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view schematically showing the structure of a multifocal magnification switching lens barrel according to the present invention.
FIG. 3 is a development view of this lens barrel as seen from the outside of the lens barrel. In addition,
In FIG. 1, the left side of the center line representing the optical axis represents a state at a short focal length position (hereinafter referred to as a wide position) of the first moving barrel, which will be described later, and the right side from the center line of the second moving barrel, which will be described later. The state at the wide position is shown.

As shown in FIG. 1, a lens barrel 1 according to the present embodiment has a fixed barrel 2 having first and second flange portions 2A and 2B fixed to the inside of a camera body, and the fixed barrel. A rotary cylinder 3 housed between the flange portions 2A and 2B of the fixed cylinder 2 so as to be rotatable coaxially with the fixed cylinder 2 on the outer side of the fixed cylinder 2.
And first and second moving barrels 4 and 5 that move forward and backward in the optical axis direction without rotating themselves as the rotating barrel 3 rotates. The first moving barrel 4 includes a front lens group. A (first lens unit) 6 is attached, and a rear group lens (second lens unit) 7 is attached to the second moving barrel 5.

A gear portion 3A is formed on the outer peripheral surface of the rear end portion of the rotary cylinder 3, and a flange portion 2B of the fixed cylinder 2 is formed.
A motor 9 which is a drive source for rotating the rotary cylinder 3 is mounted on the mounting portion 2C which is an extension of the above. The gear 10A attached to the rotating shaft of the motor 9 and the gear portion 3A mesh with each other via the idle gear 10B, and the driving of the motor 9 causes the rotating cylinder 3 to rotate about the optical axis X as the rotating shaft. Has become.

In addition, the rotary barrel 3 has a zooming cam groove 11 (for the front lens group) extending in the optical axis direction with a predetermined angular interval.
And a zooming cam groove 12 (for the rear lens group) is formed. The variable-magnification cam groove 11 and the variable-magnification cam groove 12 are formed in a state where their phases are deviated by a predetermined angle with respect to the rotation angle of the rotary cylinder 3.

The fixed barrel 2 has a guide groove 13 (for the front lens group) extending in the optical axis direction, and a focus adjusting cam extending in the optical axis direction and having three inflection portions 14A, 14B, 14C. A groove 14 (for rear lens group) is formed. These guide groove 13 and focus adjusting cam groove 14
Has a function as a so-called key groove for stably guiding the group lenses 6 and 7 in the optical axis direction. Of these, the focus adjusting cam groove 14 also has a focus adjusting function. .

The first moving barrel 4 has a cam pin 4 which penetrates the guide groove 13 of the fixed barrel 2 and engages with the zooming cam groove 11.
A is formed. The first movable barrel 4 is guided by the guide groove 13 and the zooming cam groove 11 of the rotary barrel 3 in accordance with the rotation of the rotary barrel 3, and performs the zooming operation on the front lens group 6 while performing the light scaling operation. It is designed to go straight in the axial direction.

The second movable barrel 5 is formed with a cam pin 5A which penetrates the focus adjusting cam groove 14 of the fixed barrel 2 and engages with the zooming cam groove 12. And the second moving barrel 5
Is the cam groove 1 for changing the magnification of the rotary cylinder 3 according to the rotation of the rotary cylinder 3.
2, the rear lens group 7 is operated to change its magnification, and at the same time, it is guided by the focus adjusting cam groove 14 to move its focus in the optical axis direction. As described above, the focus adjusting cam groove 14 has the inflection portions 14A, 14B and 14C and is not formed linearly like the first moving barrel 4, so that The second moving barrel 5 follows a slightly meandering path in the optical axis direction.

Next, the operation of this embodiment will be described. As shown in FIG. 2, when the cam pin 4A of the movable barrel 4 is at the position P1 and the cam pin 5A of the movable barrel 5 is at the position P1 ', the lens focus is infinity at the wide position. When the motor 9 is driven to rotate the rotary cylinder 3, the first moving cylinder 4 is guided by the zoom cam groove 11 of the rotary cylinder 3 and the guide groove 13 of the rotary cylinder 2,
On the other hand, the second movable barrel 5 is guided by the zooming cam groove 12 of the rotary barrel 3 and the focus adjusting cam groove 14 of the fixed barrel 2, and has a middle focal length position (hereinafter referred to as a middle position) P2.
It moves in the optical axis direction while maintaining a predetermined positional relationship until it reaches a long focal length position (hereinafter referred to as tele position) P3, P3 'via P2'. The middle positions P2 and P2 '
Also at the tele positions P3 and P3 ', the wide position P
The lens focus is infinitely in the same manner as 1, P1 '.

When the rotary cylinder 3 is rotated in this way,
The first moving barrel 4 moves along the locus indicated by the broken line (center line) shown on the zooming cam groove 11 in the figure, while the second moving barrel 5 moves in the drawing. The locus shown by the broken line (center line) shown above 13 is not drawn and moved, but the locus meandering with respect to this center line is drawn and moved. The movement locus of the second moving barrel 5 is shown by a chain double-dashed line in FIG. 3 showing the schematic zoom cam groove 13.

As is apparent from FIGS. 2 and 3, in the sections A, B, and C of the variable-magnification cam groove 13, the amount of movement of the second moving barrel 5 is the amount of movement of the first moving barrel 4. Smaller than quantity. Then, the focus adjustment is performed in the sections A, B, and C.

That is, the first and second moving barrels 4, 5
When the rotary cylinder 3 is slightly rotated to the feeding side when the respective positions are at the wide positions P1 and P1 ′, the first moving cylinder 4 linearly moves along the guide groove 13 of the fixed cylinder 2 as in the case of variable power. The second moving barrel 5 bends and moves in the inflection portion 14A of the focus adjusting cam groove 14, and the movement amount in the optical axis direction is the first movement as shown by the chain double-dashed line in the section A. It is smaller than the cylinder 4. During this period, the magnification of the lens system does not change, and the focus adjustment is performed from the infinite distance to the closest distance in the wide state.

Even when the magnification is increased and the first and second moving barrels 4 and 5 are at the middle positions P2 and P2 ', respectively, when the rotating barrel 3 is slightly rotated, the first moving barrel 4 is moved. Although it moves linearly along the guide groove 13 of the fixed barrel 2 as in the case of zooming, the second movable barrel 5 moves the focus adjustment cam groove 14
In the inflection part 14B, the movement amount in the optical axis direction becomes smaller than that of the first moving barrel 4 as shown by the chain double-dashed line in the section B. Even during this period, the magnification of the lens system does not change, and the focus adjustment is performed from the infinite distance to the close range in the middle state.

Further, when the first and second moving barrels 4 and 5 are in the tele positions P3 and P3 ', respectively, the rotary barrel 3 is
When is slightly rotated, the first moving barrel 4 linearly moves along the guide groove 13 of the fixed barrel 2 in the same manner as during zooming.
The second moving barrel 5 is an inflection portion 14C of the focus adjusting cam groove 14.
In the area C, the lens moves in a bending manner, and the amount of movement in the optical axis direction decreases as indicated by the chain double-dashed line in section C. In the meantime,
There is no change in the magnification of the lens system, and the focus is adjusted from infinity to the closest distance in the tele state.

As described above, in the present embodiment, since the focus adjusting cam groove 14 for adjusting the focus is formed in the fixed barrel 2, the rotary barrel 3 is mounted at the position where the desired magnification and focal length are obtained. Both rotation and focus adjustment can be performed in one continuous operation simply by rotating.
Therefore, the zooming and the focus adjustment can be performed by the motor 9, which is the same drive source, and the size and cost of the camera can be reduced.

In the above embodiment, the step-zoom in which the three inflection portions 14A, 14B and 14C are provided in the focus adjusting cam groove 14 to adjust the focus at three points has been described. It is also possible to form four or more inflection portions in the groove 14 so that focus adjustment is performed at a plurality of points. Although the fixed cylinder is arranged inside the rotary cylinder in the above embodiment, the fixed cylinder may be arranged outside the rotary cylinder. In this case, the cam pin of each moving barrel penetrates the corresponding zooming cam groove of the rotating barrel and is fitted into the cam groove (including the focus adjusting cam groove) of the fixed barrel.

In the above embodiment, the rotary cylinder is provided with the zooming cam groove and the fixed barrel is provided with the focus adjusting cam groove. However, the rotary barrel is provided with the focus adjusting cam groove. It is also possible to provide each double cam groove. Furthermore, in the above-described embodiment, the focus adjustment is performed by using the whole feeding method, but it is of course possible to perform the focus adjustment only by moving the rear lens group or the front lens group.

[0022]

According to the multifocal magnification switching lens barrel of the present invention,
The rotation of the rotary cylinder moves the first lens unit in the optical axis direction, and the second lens unit is guided by the first guide portion to perform zooming. First and second
The lens unit is moved in the optical axis direction by being guided by the fixed barrel, but since the second barrel for guiding the second lens unit for focus adjustment is provided in the fixed barrel, the rotating barrel is rotated. Then, the focus of the second lens unit is adjusted by the second guide portion. Therefore,
Since the multifocal magnification switching lens barrel of the present invention can perform zooming and focus adjustment only by rotating the rotary cylinder, zooming and focus adjustment can be performed by the same drive source, and the camera It is possible to realize downsizing and cost reduction.

[Brief description of drawings]

FIG. 1 is a sectional view showing a multifocal magnification switching lens barrel according to an embodiment of the present invention.

FIG. 2 is a development view of a rotary cylinder and a fixed cylinder of the embodiment shown in FIG.

FIG. 3 is a schematic diagram showing a movement trajectory of a rear group lens in the embodiment shown in FIG.

[Explanation of symbols]

 1 Multifocal magnification switching lens barrel 2 Fixed barrel 3 Rotating barrel 4 First moving barrel 4A, 5A cam pin 5 Second moving barrel 6 Front lens group 7 Rear group lens 9 Motors 10A, 10B Gears 11, 12 Zooming cams Groove 13 Guide groove 14 Focus adjustment cam groove

Claims (2)

[Claims] 1. A first lens unit and a second lens unit, which are arranged in front and rear on an optical axis, and are rotatably provided around the optical axis, and the two lens units are respectively moved according to the rotation. A rotary cylinder having a first guide portion, and a second cylinder provided inside or outside the rotary cylinder for guiding the two lens units that move in accordance with the rotation of the rotary cylinder in the optical axis direction. A fixed barrel having a guide portion, and one of the first and second guide portions guides each of the two lens units in accordance with the rotation of the rotary barrel to perform magnification switching. The other of the first and second guide portions guides at least one of the two lens units in accordance with the rotation of the rotary cylinder to perform focus adjustment of the entire system. It is characterized by being configured as Multifocal magnification switching lens barrel. 2. The multifocal magnification switching lens barrel according to claim 1, wherein the first and second guide portions act on at least one of the lens units when the other is inoperative.