JP2000089088A - Lens barrel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lens barrel constituted so that the positional deviation of lens groups caused by a conventional lens barrel is eliminated and an extremely accurate focusing action can be executed with a simple constitution. SOLUTION: The focusing action of this lens barrel is executed as follows. A gap between a second-group lens holding frame 26 holding a second group lens 15 being the focusing lens group and a third group frame 27 holding a third group lens being the other lens group whose gap exerts the largest effect on an image forming position is detected by a differential transformer 28, and a ring-like focusing cam 9 is driven according to the detection output of the gap between the frames so as to drive the lens 15 to a proper position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel, and more particularly to a lens barrel in which a lens group constituting a lens barrel is driven and controlled to an appropriate position.

[0002]

2. Description of the Related Art In recent years, especially in a lens shutter camera, a zoom lens has become extremely popular, and a zoom range has been expanded and a zoom lens system has been downsized. Under such circumstances, in order to obtain a photograph with good focus, how to improve the focusing accuracy has become a major issue. For this reason, many proposals have been made regarding the focus position drive control of the zoom lens. The present applicant has previously proposed in Japanese Patent Application No. 2-106393,
The present invention relates to a zoom lens barrel having a multi-group lens configuration, and in this lens barrel, focus position drive control of a focusing lens group is performed based on the number of pulses delivered from a reference detection position.

The structure of the zoom lens barrel will be described in detail. FIG. 5 is a longitudinal sectional view of the zoom lens barrel. The zoom lens barrel 50 is an inner focus type zoom lens barrel, which includes a cylindrical fixed frame 2 and an outer periphery of the fixed frame. , A cylindrical cam ring 1 is rotatably fitted. A screw portion 20 is formed on the inner peripheral surface of the distal end portion of the cam ring 1.
1 is screwed. By rotating the adjustment ring 21, the cam ring 1 can be slightly moved in the axial direction. A holding ring 22 is attached to the outer periphery of the distal end of the fixed frame 2 and is in contact with the adjustment ring 21.

In the fixed frame 2, a cylindrical moving frame 3 is provided.
Are movably inserted along the axial direction. Three roller pins 18 (only one is shown) are attached to the outer periphery of the moving frame 3, and each roller pin is fixed to the fixed frame 2.
And is inserted into a first cam groove 1a formed in the cam ring 1. The straight groove 2a extends along the axial direction of the fixed frame 2, and the cam groove 1a is formed in a spiral shape. Therefore, the cam ring 1
Is rotated, the moving frame 3 moves linearly along its axial direction. Further, a light-shielding cloth 23 is attached to the inner peripheral surface of the distal end portion of the fixed frame 2 so as to prevent light from entering the gap between the fixed frame 2 and the movable frame 3 from the outside, and is in sliding contact with the outer peripheral surface of the movable frame 3. .

In the moving frame 3, first, second, and third group lenses 14, 15, and 16 constituting a photographing optical system are provided. The second lens group 15 is a focusing lens group. Describing each lens group in detail, the first group lens 14 is supported in the moving frame by the first group frame 24 screwed into the tip of the moving frame 3. A cylindrical second group frame 4 is fitted to an intermediate portion in the moving frame 3 so as to be movable in the axial direction. The second group frame 4 is provided with three roller pins 17 (only one is shown) projecting therefrom. Each roller pin 17 has a straight groove 3 a formed in the moving frame 3 and a straight line groove formed in the fixed frame 2. It penetrates the groove 2a and is inserted into a spiral second cam groove 1b formed in the cam ring 1. Therefore, by rotating the cam ring 1,
The second group frame 4 moves in the moving frame 3 along the axial direction.

A plurality of focusing guide shafts 10 (only one is shown) are fixed to the second group frame 4,
Extending parallel to the axis. And these guide shafts 1
The front holding frame 6 and the rear holding frame 7 which hold the second group lens 15 by 0 support the movable frame 3 movably along the axial direction. A focusing spring 5 is wound around each guide shaft 10, and the front holding frame 6 and the rear holding frame 7 are urged rearward by the spring. Therefore, the pin 8 protruding from the rear holding frame 7 is pressed against the cam surface of the ring-shaped focusing cam 9. When the focusing cam 9 is rotated by a driving unit (not shown), the front holding frame 6 and the rear holding frame 7
As a result, the lens is moved forward against the urging force of the spring 5, and as a result, the second lens unit 15 is extended to perform focusing. In addition, between the front holding frame 6 and the rear holding frame 7, a shutter blade 25 also serving as an aperture is provided.

A third group frame 12 is fitted into the base end of the moving frame 3 so as to be movable in the axial direction of the moving frame. Three roller pins 19 (only one is shown) protrude from the third group frame 12, and each roller pin 19 is formed in a linear groove 3b formed in the moving frame 3 and a fixed frame. It penetrates the straight groove 2a and is inserted into a spiral third cam groove 1c formed in the cam ring 1. Therefore, when the cam ring 1 is rotated, the third group frame 12 moves in the moving frame 3 in the axial direction. The holding frame 11 holding the third group lens 16 is fitted and fixed to the inner periphery of the third group frame 12. By adjusting the relative position between the third group frame 12 and the holding frame 11 by a known mechanism (not shown), the focus movement during zooming can be corrected.

FIG. 6 shows the movement of each lens group during zooming of the conventional lens barrel 50. The first lens group 14, the second lens group 15, and the third lens group 16 of the photographing lens are zoomed. Move as shown. FIG. 7 is a diagram showing a state of focusing control in the lens barrel 50 of the conventional example. The pin 8 of the second group lens rear holding frame 7 is in contact with the cam surface of the focusing cam 9, and when the focusing drive motor (not shown) starts rotating while generating a feeding pulse, the focusing cam 9 also starts rotating. The AF switch 13 which is in contact with the outer periphery of the focusing cam 9 at a certain rotation position changes from ON to OFF.
Starts counting the pulses of the focusing motor.
Before this operation, the focusing drive amount suitable for the shooting distance of each subject is set as the number of drive pulses (eg, the pulse number Pn if the subject is closest). The number Pn is counted, and the focusing is stopped when the second group lens 15 is extended to the in-focus position via the pin 8 (timing t).
2). Then, after the shutter differential is completed, the focusing motor is driven again by the number of reset pulses PR to return to the initial position (timing t3). In this manner, a series of sequence operations of focusing drive and shutter differential are completed.

[0009]

Generally, in the case of a zoom lens, the total focal length fT of the lens system is expressed by the following equation.

[0010]

FT = f1 .beta.2 .beta.3... .Beta.n (1) where n is the number of zoom groups, f1 is the focal length of the first group, and .beta.
i is the magnification of the i-th lens group. Also, when the principal point interval between the i-th zoom group and the (i + 1) -th zoom group is Di,
The deviation ΔDi of the value Di and the deviation ΔfBi of the image plane position due to the deviation ΔDi are expressed by the following equations.

[0011]

In Equation 2] ΔfBi = {(βi + 1 · βi + 2 · ...... · βn) 2 -1} · ΔDi ...... (2) The equation (2), depending on the principal point distance Di (.beta.i +
1 ····· βn) ² may have a very large value in the telephoto state, which may greatly affect the deviation ΔfBi. In the case of an inner focus lens barrel,
When the i-th zoom group is focused, the imaging position deviation amount ΔfBi ′ based on the focus movement amount ΔFi is expressed by the following equation.

[0012]

ΔfBi ′ = ｛(βi + 1 ···· βn) ² − (βi · βi + 1 ···· βn) ² ｝ xΔFi (3) FIG. FIG. 3 is a diagram showing a zooming state of a three-unit zoom lens barrel having the characteristics shown in FIG. The focal lengths f1, f2, and f3 of the first, second, and third lens groups are 68.73, 23.60, and 21.13 (mm), respectively. Further, Table 2, .beta.3 ² is a (magnification) ² values at each zoom of the zoom lens ^barrel, (.beta.2 · .beta.3)
^It shows values such as ² . Further, FIG. 9, which value .beta.3 ^2, shows the change in the (β2 · β3) ^2.

[0013]

[Table 1]

[Table 2] As can be seen from these figures and the like, the effect on the imaging plane position shift due to the principal point distance D2 between the second and third lens units is 13.68 times as shown in Table 2 in the telephoto state and the above equation (2). Which is about 10 times as large as the effect of the case between the first and second groups, which is 1.22 times. Therefore, when the second group lens is used for focusing, it can be said that direct control of the distance between the second group and the third group improves the driving accuracy with respect to the target imaging position.

Regarding the above-described image forming position accuracy, in the case of the conventional zoom lens barrel 50 of FIG. 5, the principal point distance D2 between the second lens unit 15 and the third lens unit 16 is more important for focusing accuracy. It turns out that. However,
As described above, since the focusing drive is performed by controlling the number of drive pulses of the drive motor, occurrence of an error in the principal point interval D2 is inevitable. The main factor is that there is an error in the zooming stop position of the second group lens 15 and the third lens 16 driven by the rotation of the cam ring 1. This includes cam 1
b, 1c, abrasion of the pins 17, 19, and the like. In addition, an error in the focusing drive itself is also a factor. This includes wear of the AF cam 9, timing deviation due to chattering of the AF switch 13, and the like. Further, there is a dimensional change due to the temperature and humidity of the frame components, and in the above-mentioned conventional example, the above-mentioned factors could not be completely eliminated.

FIG. 10 shows a change diagram required for the above-mentioned second and third lens unit distance D2 with respect to the focal length between wide / telephoto, and at a certain focal length x at infinity ( I) The interval D2 for focusing on the subject is the value D.
x, indicating that the maximum focusing movement amount of the second lens unit 15 at x is FX. In other words, point A indicates the focusing position of the second group lens 15 that is focused on ∞ at the focal length x, and point B indicates the position of the two groups that are similarly focused closest.

Similarly, values Dw and Dt are wide,
Telespace interval D2 is shown, and values Fw and Ft indicate the changing state of interval D2 due to widening and telefocusing, respectively. It is necessary to control the distance D2 between the second and third lens groups based on this diagram.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and in a lens system requiring high-precision focusing drive control, the position error of the lens group, which has occurred in the conventional example, is remarkably reduced. An object of the present invention is to provide a lens barrel capable of performing focusing driving control with a simple configuration and extremely high accuracy so that the number of lens barrels can be reduced.

[0018]

A lens barrel according to the present invention is a lens barrel comprising a plurality of lens groups, a lens group driving means for moving the lens groups forward and backward in the optical axis direction,
A lens group other than the lens group; a frame interval detecting unit for directly detecting an interval between the holding frames of the lens group and the other lens group; and the lens according to an output of the frame interval detecting unit. Control means for operating the group driving means to stop the lens group at an appropriate position, and the frame interval detecting means is a differential transformer.

A lens barrel according to the present invention is a lens barrel provided with a plurality of lens groups having at least one lens holding frame movable in an optical axis direction, the lens barrel being held by the lens holding frame. Another lens holding frame for holding another lens group different from the lens group, and provided so as to straddle the two lens holding frames in order to directly detect the interval between the two lens groups. And a detecting element, wherein the detecting element is a differential transformer.

Further, the lens barrel according to the present invention comprises a plurality of lens groups including at least one movable lens group, object information detecting means, a driving means for driving the movable lens group of the plurality of lens groups, In the lens group, the actual distance to the specific lens group of the plurality of lens groups with respect to the movable lens group is output as a value corresponding to the actual distance by directly measuring the position from the movable lens group. And a control unit that controls the driving unit so that the specific lens group is located at an appropriate position based on the subject information and a value corresponding to the actual distance. The position detecting means is characterized in that:
It is a differential transformer that detects a lens group interval as a potential difference.

Further, a lens barrel according to the present invention is a lens barrel having a plurality of lens groups including at least one lens group movable in the optical axis direction, wherein the lens group movable in the optical axis direction is A detection element for directly detecting an interval between two lens groups with another lens group different from the lens group is provided, and the detection element is a differential transformer. I do.

Further, the lens barrel according to the present invention comprises:
A pair of lens groups that move relative to each other, and a detecting unit having two elements for directly detecting a relative distance between the pair of lens groups, and one element of the detecting unit is directly connected to the pair of lens groups. And the other element of the detecting means is provided directly on the other of the pair of lens groups, wherein the detecting means is a differential transformer, and the one element is a dielectric core. Yes, the other element is characterized by comprising a cylindrical coil.

(Operation) The distance between the holding frames of the lens group and the other lens groups is detected, and the lens group driving means is operated in accordance with the frame distance detection output to stop the lens group at an appropriate position.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the illustrated embodiment. FIG. 1 is a longitudinal sectional view of a main part of a lens barrel showing a first embodiment according to the present invention. The lens barrel 60 is a zoom lens having a three-group lens configuration,
In FIG. 1, a cam ring 1, a fixed frame 2, a part of a moving frame 3,
Although not shown, the first group lens and the like have the same configuration as that of the lens barrel 50 in FIG. Note that the second lens group 15 is also a focusing lens group.

A core shaft 27 protruding from the third group frame 27 holding the third group lens 16 along the optical axis direction.
A cylindrical dielectric core 28c as an element is fixed to the tip of a, and the cylindrical shape of the second group lens holding frame 26 holding the second group lens 15 so as to cover the core 28c in the circumferential direction. Arm 26a is provided. In this arm 26a,
Cylindrical primary coil 28a and secondary coil 2 as elements
8b is wound, and the core 28c constitutes a differential transformer 28 as frame interval detecting means. The second group lens holding frame 26 is provided with a plurality of focusing guide shafts 10 on a second group frame 29 which is slidably fitted on the inner peripheral side of the moving frame 3.
(Only one is shown). The third lens group 16 is a lens group in which the relative position change with respect to the second lens group 15, which is the focusing lens group, is greatest during focusing.

In the focusing drive in the lens barrel 60, the relative position of the third group frame 27 and the second group lens holding frame 26, that is, the distance between the second and third lens groups D2 shown in FIG. 28b is detected as a difference voltage, and based on the detected voltage, a driving motor (not shown) serving as a focusing lens group driving unit instructs by a control unit such as a CPU (not shown).
The AF cam 9 is rotated to move the second lens holding frame 26 to an appropriate focusing position. The flow of the focusing drive operation and the photographing operation will be described later.

According to this embodiment, the third group frame 27 and the third group frame 27, which determine the relative position (D2) of the second group lens 15 with respect to the third group lens 16, which has a greater influence on the imaging position. The frame interval of the second group lens holding frame 26 can be directly detected as the output of the differential transformer. Therefore,
An error of the cams 1b and 1c of the cam ring and a wear error of the AF cam 9 can be completely removed. Further, even if the second group frame 29 supporting the second group lens holding frame undergoes a dimensional change due to temperature and humidity, the relative position of the second group lens 15 can be detected without being affected by the dimensional change. Focus driving is possible.

FIG. 2 is a longitudinal sectional view of a main part of a lens barrel showing a second embodiment according to the present invention. Main lens barrel 70
This is also an inner focus type zoom lens barrel having a three-group configuration, which includes a cylindrical fixed frame 32, and a cylindrical cam ring 31 is rotatably fitted around the outer periphery of the fixed frame 32. A cylindrical moving frame 33 for holding a first group lens (not shown) is inserted into the fixed frame 32 so as to be movable in the axial direction. Three roller pins 42 (only one is illustrated) are attached to the outer periphery of the moving frame 33, and each roller pin 42 passes through a straight groove 32 a formed in the fixed frame 32, and the cam ring 31. Is inserted into the first cam groove 31a formed in the first cam groove. The straight groove 32a extends along the axial direction of the fixed frame 32.
a is spirally formed on the cam ring 31. Therefore,
By rotating the cam ring 31, the moving frame 33 moves linearly along its axial direction.

In the moving frame 33, a first group lens (not shown) and a second group lens
5. Third lens group 16 is provided. The second group lens 15 is a focusing lens group, and the second group lens 15 and the third lens 15
It is assumed that the change in the distance from the group lens 16 (the distance between the principal points) is larger than the change in the distance from the first lens group.

The support structure of those frames will be described in detail.
A third group frame 34 that supports the third group lens 16 is fitted inside the base end of the moving frame 33 so as to be movable along the axial direction of the moving frame 33. Three roller pins 43 (only one is shown) project from the third group frame 34, and each roller pin has a linear groove 33 b formed on the moving frame 33 and a linear groove formed on the fixed frame 32. 32a through the cam ring 3
1 is inserted into the spiral second cam 31b. Therefore, when the cam ring 31 rotates, the third group frame 34 moves in the moving frame 33 along the axial direction.
Further, a guide shaft 38 for moving the second group lens holding frame 35 holding the second group lens 15 in the axial direction is fixed to the third group frame 34.
The third group frame 34 is supported by the guide shaft 38.
It is arranged inside. At the time of zooming and focusing, the rotation of the output gear 41a of the motor 41 is fixed to the third group frame 34 via the reduction gear 40 composed of the gears 40a and 40b. The power is transmitted to the gear 39a attached to the feed screw 39,
9 to rotate the second group lens holding frame 35 to the guide shaft 3
Move along 8.

The third group frame 34 has a core shaft 34a parallel to the guide shaft 38, and a dielectric core 36c is fixed to the center of the core shaft 34a. The cylindrical arm 35a of the second lens group holding frame 35 is formed so as to cover the core 36c in the circumferential direction.
Is provided. A cylindrical primary coil 36a and a secondary coil 36b are wound around the arm 35a, and the core 36c constitutes a differential transformer 36 as frame interval detecting means. With this differential transformer 36, the interval between the second and third lens groups can be detected, and the second lens group holding frame 35 can be detected.
Can be determined with reference to the third group frame 34.

Now, in the lens barrel of this embodiment configured as described above, the driving control method at the time of zooming is as follows. In the diagram showing the lens interval for each focal length, it is desirable to drive along a focusing line passing through point C which is an intermediate point between point A corresponding to ∞ and point B corresponding to the closest position. The value of the interval D2 on the focusing line is given by the following equation.

[0033]

## EQU4 ## D2 = Dx + (Fx / 2) (4) By performing the zooming drive as described above, even if the subject is in a far or near position during focusing,
The amount of movement of the second lens group holding frame 35 is minimized on average, and as a result, the focusing operation can be shortened so that a photo opportunity is not missed.

In the second embodiment, the second group frame 29 of the first embodiment is omitted, and the second group lens holding frame 35 is directly connected to the third group frame 34. It is supported by. Therefore, the error based on the second group frame is removed from the relative position of the second group lens 15 with respect to the third group lens 16 which greatly affects the imaging position, and the accuracy is further improved. Further, according to this configuration, the motor 41
Since the second group lens holding frame 35 is driven by zooming and focusing by the driving force described above, the second group frame, the second group pins, the cam for the second group frame of the cam can, and the like can be omitted as described above. This also contributes to downsizing and cost reduction of the camera. It is also possible to drive both the focusing movement and the zoom movement at the time of focusing driving without driving the second lens group holding frame 35 during zooming.

FIG. 3 is a longitudinal sectional view of a main part of a lens barrel according to a third embodiment of the present invention. The lens barrel of this embodiment uses a photo-interrupter instead of the differential transformer 28 as the frame interval detecting means used in the first embodiment of FIG. That is, the second group lens 15
The plate-shaped arm 45 is attached to the second group lens holding frame 45 for holding
a, the third group frame 46 for holding the third group lens 16
And the optical path of the photointerrupter 44 fixed to the third group frame 46 can be shielded. Note that the second group lens 15 is a focusing lens group, and in the focusing operation, a change in the distance (principal point interval) between the second group lens 15 and the third group lens 16 is different from that of the first lens group. Is greater than the change in distance.

During the zoom operation, the relative positions of the second lens group holding frame 45 and the third lens group frame 46 are always kept in a state where the optical path of the photointerrupter 44 shown in FIG. 5 is shielded. If the second group lens holding frame 45 is driven forward in the optical axis direction by a focusing motor (not shown) during focusing driving, the arm 45a of the second group lens holding frame 45 is retracted from the photo interrupter 44, so that the photo interrupter 44 is It turns on. The timing at which the photointerrupter 44 turns from off to on is used instead of the off timing of the AF switch 13 of the conventional example shown in FIG. 7, and the subsequent focusing drive similarly counts the drive pulse from the reference position. It is done by doing.

In the third embodiment, the third group frame 4
A specific position of the second group holding frame 45 with respect to 6 is directly detected, and focusing control is performed on the basis of the specific position in the same manner as in the conventional example. The effect of this case is that the AF switch 13 of the conventional example shown in FIG.
Switching timing of the photo interrupter 4
The ON / OFF signal switching timing of No. 4 is output directly with respect to the third group frame 46. Thus, it is possible to prevent a cam error of the cam ring 1 and a timing error due to chattering of the AF switch 13 in the conventional example.

Next, the focusing control and the photographing operation of the lens barrel according to the first and second embodiments will be described with reference to the flowchart of FIG. First, a target position of the second lens group 15 with respect to the third lens group 16 is set based on the distance measurement result (steps S11 and S12). Then, the focusing motor is driven to drive the differential transformer 28 of the interval detecting means. Alternatively, the second group lens 15 is accurately stopped at the target position, that is, the in-focus position while reading the output of 36 (steps S13, S14, S15). Thereafter, the shutter is made differential to execute photographing (step S16). Then, the film is wound up, the focusing motor is reset, and the camera operation is completed (step S17,
18). The resetting operation of the focusing after the film is wound is to reset the second lens group 15 to a predetermined position in order to quickly perform the next focusing. However, this operation may be omitted.

In the lens barrel according to the third embodiment, the position of the second lens group 15 is detected only at a specific point. Therefore, it is determined whether the second lens group 15 has reached the target position. Judgment cannot be made directly on the basis of the third lens group 16. Therefore, the second group lens 1
The target position of No. 5 is set by the number of pulses as in the case shown in FIG. 7, and while the driving pulse of the focusing motor is counted, the second group lens 15 is stopped when the set pulse is detected. Become.

[0040]

As described above, the lens barrel of the present invention directly detects the distance between the holding frames of the lens group and the other lens groups, and outputs the lens group according to the frame distance detection output. Is driven to an appropriate position, the present invention eliminates the positional deviation of the lens group that has occurred in the conventional example, and enables effective and highly accurate lens drive control. The structure has a very remarkable effect such as a simple structure.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part around a second and third lens groups of a lens barrel according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a main part around a second and third lens group frame of a lens barrel according to a second embodiment of the present invention.

FIG. 3 shows a second lens barrel showing a third embodiment of the present invention.
FIG. 6 is a vertical sectional view of a main part around a third lens group frame.

FIG. 4 shows focusing of the lens barrel shown in FIGS.
And a flowchart of the photographing process.

FIG. 5 is a longitudinal sectional view of a main part of a zoom lens barrel showing a conventional example.

FIG. 6 is a diagram showing the extended state of each lens group during a zooming operation of the zoom lens barrel of FIG. 5;

FIG. 7 is a diagram showing a relationship between a cam lift and a count state of a delivery pulse during a focusing operation of the zoom lens barrel of FIG. 5;

FIG. 8 is a diagram showing a state in which a general zoom lens is extended during zooming.

9 is a diagram showing a change in magnification with respect to each zoom position in the zoom lens shown in FIG. 8;

FIG. 10 is a diagram showing a change in the distance between the second and third lens groups with respect to each zoom position in the zoom lens of FIG. 8;

[Explanation of symbols]

9 Focusing cam (lens group driving means) 15 Second group lens (lens group) 16 ……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………. ............ Third group frame (holding frame) 28a, 36a ... Primary coil (frame interval detecting means) 28b, 36b ... ... Secondary coil (frame interval detecting means) 28c, 36c core (frame interval detecting means) 28, 36... (Frame interval detecting means) 34... Third group frame (holding frame) 35...... Group lens holding frame (holding frame) 39 ............ Feed screw (lens group driving means) 39a ...... Gear (lens group driving means) 40 ... ………………………………………………………………………………………………………………………………………………………………………………………………… (motors) ……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………… No. …………… Third group frame (holding frame)

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takeshi Ito 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside Olympus Optical Industrial Co., Ltd. (72) Inventor Yoji Terada 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd.

Claims (10)

[Claims] 1. A lens barrel comprising a plurality of lens groups, a lens group driving means for moving the lens group back and forth in the optical axis direction, a lens group other than the lens group, the lens group and the other Frame interval detecting means for directly detecting the interval between the holding frames of the lens groups; control means for operating the lens group driving means in accordance with the output of the frame interval detecting means to stop the lens group at an appropriate position A lens barrel, comprising: 2. The lens barrel according to claim 1, wherein said frame interval detecting means is a differential transformer. 3. A lens barrel provided with a plurality of lens groups having at least one lens holding frame movable in an optical axis direction, the lens barrel being different from the lens group held by the lens holding frame. Another lens holding frame for holding another lens group, and a detecting element provided across the two lens holding frames to directly detect the interval between the two lens groups. A lens barrel characterized by: 4. The lens barrel according to claim 3, wherein said detection element is a differential transformer. 5. A plurality of lens groups including at least one movable lens group; subject information detecting means; driving means for driving the movable lens group of the plurality of lens groups; and in the lens group, the movable lens The actual distance to a specific lens group of the plurality of lens groups with respect to the group,
Position detecting means for directly outputting a value corresponding to the actual distance by directly measuring a position from the movable lens group, and the specific lens group based on the subject information and the value corresponding to the actual distance. Control means for controlling the driving means so as to come to an appropriate position. 6. The lens barrel according to claim 5, wherein said position detecting means is a differential transformer that detects a distance between lens groups as a potential difference. 7. A lens barrel having a plurality of lens groups including at least one lens group movable in the optical axis direction, wherein the lens group movable in the optical axis direction and another lens group different from the lens group. A lens barrel provided with a detection element for directly detecting an interval between two lens groups with respect to a lens group. 8. The lens barrel according to claim 7, wherein said detection element is a differential transformer. 9. A pair of lens groups which relatively move, and a detecting means having two elements for directly detecting a relative distance between the pair of lens groups, and one element of the detecting means is provided. A lens barrel, wherein the lens element is provided directly on one of the pair of lens groups and the other element of the detection means is directly provided on the other of the pair of lens groups. 10. The lens barrel according to claim 9, wherein said detecting means is a differential transformer, said one element is a dielectric core, and the other element is a cylindrical coil. .