JPH1062678A - Zoom lens device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform magnification change and focusing using a single motor and change the focal distance continuously. SOLUTION: A moving cylinder 11 is equipped internally with a driven ring 12, front group lens frame 13, drive ring 14, straight advancing cylinder 15 and rear group lens frame 16, and rotates relatively with a stationary cylinder 10 so as to move two lens groups 13 and 16 in the direction of optical axis 20, and magnification change is made by changing the distance between the two lens groups. The rotation of a motor 25 is transmitted to the drive ring 14 inside the moving cylinder 11. The drive ring 14 is coupled rigidly with the front group lens frame 13 and coupled with the driven ring 12 through a gap in the rotating direction centering on the optical axis 20. At the time of magnification change, the arive ring 14 is rotated beyond the extent of the gap, and the cylinder 11 is rotated through the driven ring 12. At the time of focusing, the drive ring 14 is rotated within the extent of the gap, and the driven ring 12 is put in the stopped condition, and the front group lens frame 13 is moved as following the lead of helicoids 36 and 37.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION At least two lens groups are relatively moved in the direction of the optical axis by using the drive of one motor to perform magnification, and then one of the lens groups is moved in the direction of the optical axis. The present invention relates to a zoom lens device that moves and focuses.

[0002]

2. Description of the Related Art A zoom lens which performs a zooming operation and a focusing operation using a common motor is disclosed in Japanese Patent Publication No. 6-100.
No. 707 is proposed. This zoom lens
A first cam groove which includes a zoom ring, two lens groups, a motor for rotating the zoom ring, and the like, and performs a variable power operation by relatively moving the two lens groups on the inner periphery of the zoom ring. And a second cam groove for performing a focusing operation by moving the lens group so as to draw a locus different from the first cam groove. The second cam grooves are alternately provided on an extension of the first cam groove, and determine a focusing position for each zooming position in accordance with a rotation angle of a zoom ring that is rotated by driving a motor.

[0003]

In such a zoom lens, a first variable power position, a focusing range at the first variable power position, a second variable power position, and a second variable power position are sequentially used. Since the cam groove is composed of a cam groove obtained by combining the first cam groove for zooming and the second cam groove for focusing so that the focusing range at the double position is... It can be used only at a position predetermined for each step on the zoom trajectory, and therefore there is a possibility that the focal length intended by the photographer cannot be changed. Further, the cam groove is inevitably long, which is disadvantageous when increasing the zoom speed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and in the case of performing zooming and focusing using the driving of one motor, the focal length of a zoom lens can be continuously changed. It is an object of the present invention to provide a zoom lens device capable of increasing a zoom speed.

[0005]

In order to achieve the above object, a zoom lens device according to the present invention comprises a drive ring for rotating a front group lens in the direction of the optical axis by rotating about a light axis by driving a motor; : A front lens group and a rear lens group are built in, and are connected to the drive ring with a gap in the rotation direction thereof. When the drive ring rotates beyond the range of the gap, the rotation is used to make an optical axis direction. Moved to
A moving cylinder which stops rotating around the optical axis when the driving ring rotates in the gap; and The magnification is changed by changing the distance between the two lens groups, and by rotating the drive ring in the gap, the drive ring rotates relative to the moving cylinder to move the front lens group. It is moved in the optical axis direction to perform focusing.

At the time of zooming, the driving ring is rotated beyond the range of the gap by driving the motor. Thereby, the rotation of the drive ring is transmitted to the movable barrel, and the movable barrel rotates together with the drive ring. By the rotation of the moving cylinder, the two lens groups are moved together in the optical axis direction, and the distance between the two lens groups is changed to perform zooming. At the time of focusing, the drive ring is rotated within the gap by driving the motor. At this time, the rotation of the drive ring is not transmitted to the moving barrel, so that the driving ring rotates relative to the moving barrel, and only the front lens moves in the optical axis direction to perform focusing.

According to a second aspect of the present invention, a male helicoid is formed on an outer periphery of the drive ring, and a front lens frame for holding the front lens is integrally provided. The male helicoid is attached to the movable barrel. The drive ring moves the front group lens in the optical axis direction according to the lead of the helicoid by integrally attaching a driven ring formed on the inner periphery with a female helicoid engaged with the head ring and rotating the drive ring in the gap. It is like that.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIGS. 1, 2 and 3, a zoom lens apparatus according to the present invention
A moving cylinder 11, a driven ring 12, a front group lens frame 13, a driving ring 14, a rectilinear cylinder 15, a rear group lens frame 16,
Two-component mechanical correction type 2 composed of a linear guide frame 17 and the like
Description will be given as a group zoom lens.

The movable barrel 11 moves along the optical axis 20 while rotating according to the leads of the helicoids 18 and 19 formed inside the fixed barrel 10. Moving cylinder 11
, A driven ring 12, a front lens frame 13, a drive ring 14, a rectilinear barrel 15, and the like are built therein.

The straight barrel 15 is rotatably attached to the movable barrel 11, and a straight guide frame 17 is fixed to the rear end. Guide projections 21 are formed on the outer periphery of the linear guide frame 17. The guide projections 21 are respectively engaged with straight opening guide openings 22 formed in the fixed cylinder 10. This allows
The rectilinear barrel 15 moves along the direction of the optical axis 20 integrally with the movable barrel 11 in a state where it is prevented from rotating.

A gear 23 is attached to a part of the guide projection 21 of the straight guide frame 17. The gear 23 is connected to a drive gear 24 through a part of the opening 22 of the fixed cylinder 10.
Are engaged with each other, and the motor 25
Is transmitted. The driving gear 24 is connected to the optical axis 20.
Moving cylinder 11
, The meshing state with the gear 23 is maintained.

The gear 23 drives the motor 25 to drive the straight cylinder 1
5 is transmitted to a gear 26 incorporated therein. Gear 26
The other gear 28 is connected to the shaft 27 on the front side of the rectilinear barrel 15. The shaft 27 has a straight barrel 1 at both ends.
5 and a linear guide frame 17 rotatably supported.
The gear 28 meshes with a sector gear 29 formed on a part of the outer periphery of the drive ring 14, and rotates the drive ring 14 around the optical axis 20. The driving ring 14 is moved between the driven ring 12 and the driving ring 14 inside the moving cylinder 11 in a state where the movement in the direction of the optical axis 20 is prevented and the rotation around the optical axis 20 is allowed. It is built in. The drive ring 14 is provided with a notch 31 formed by cutting a driven ring 12 along a rotation direction of a driven ring 12 with a fork portion 30 formed on an inner periphery thereof, and a gap in a rotation direction about the optical axis 20. When the drive ring 14 rotates beyond the range of the gap, both outer sides of the fork portion 30 press both end walls 31 and 31 b of the cutout portion 31 to rotate the driven ring 12. The driven ring 12 is fixed to a front wall of the moving cylinder 11 with a screw or the like, and rotates together with the moving cylinder 11.

A rear group lens frame 16 is provided inside the rectilinear barrel 15.
Are movably incorporated in the direction of the optical axis 20. A cam pin 32 is attached to the outer periphery of the rear lens group frame 16 so as to protrude. These cam pins 32 are engaged with cam grooves 34 formed on the inner periphery of the movable cylinder 11 via straight guide holes 33 formed in the straight cylinder 15. These cam grooves 34 move the rear lens group frame 16 forward and backward along the direction of the optical axis 20 by displacement in accordance with the rotation of the movable barrel 11.
As a result, when the drive ring 14 rotates beyond the gap, the movable barrel 11 rotates via the driven ring 12, and the front lens frame 13 and the rear lens frame 16 move together with the movable barrel 11 along the optical axis 20. And the rear group lens frame 16 is moved by the displacement of the cam groove 34 so that the front group lens frame 1
3, the distance between the lens groups is changed, and the focal length of the taking lens is changed.

Inside the driven ring 12, a female helicoid 36 for focusing is formed. A male helicoid 37 formed on the outer periphery of the front lens group frame 13 is engaged with the helicoid 36. A projection 38 is formed on the outer periphery of the rear end of the front lens frame 13. This projection 3
Numeral 8 is not fitted between the notch 31 of the driven ring 12 and the fork 30 of the drive ring 14, and transmits the rotation of the drive ring 14 to the front lens group frame 13.

At the time of focusing, the driving ring 1 is moved within the gap.
4 is rotated. The rotation of the drive ring 14 is transmitted to the front group lens frame 13, and the front group lens frame 13 rotates relatively to the driven ring 12. As a result, the front lens group 13 moves in the direction of the optical axis 20 according to the leads of the helicoids 36 and 37. In addition, since the front group lens frame 13 moves relative to the drive ring 14 along the direction of the optical axis 20, the fork unit 30 is engaged with the projection 38 even when the front group lens frame 13 moves. The length along the direction of the optical axis 20 is formed long so as not to cancel the combination.

The driving of the motor 25 is controlled by a controller 40 via a driver 39, as shown in detail in FIG. The control unit 40 performs zooming control for driving the motor 25 in response to the operation of the zoom button 41. The zoom button 41 includes a tele side zoom button 41a for continuously changing the focal length of the zoom lens toward the tele side and a wide side zoom button 4 for changing the focal length toward the wide side.
1b. In the variable power control, the motor 25 is driven to rotate forward in response to the operation time of the tele side zoom button 41a. The motor 25 is driven to rotate in reverse in response to the operation time of the wide-side zoom button 41b. In the drawing, reference numeral 42 denotes a film surface, reference numeral 43 denotes a front cover, and reference numeral 44 denotes a shutter block fixed inside the rectilinear barrel 15.

The linear guide frame 17 is provided with a brush 48 that slides on a variable resistance plate 47 fixed to the fixed cylinder 10. The brush 48 is connected to the control unit 40. The control unit 40 reads the amount of movement of the movable barrel 11 that moves during zooming with a signal corresponding to the resistance value obtained from the brush 48, and determines the zoom position based on this signal.

The focus control of the control unit 40 is performed by operating the distance measuring mechanism 50 in response to the half-pressing operation of the shutter button 49, obtaining the subject distance information from the distance measuring mechanism 50, and then increasing the number of pulses corresponding to the information. The motor 25 is driven. The number of pulses is determined for each subject distance, and these are stored in the ROM 51 in advance. The pulse data stored in the ROM 51 is all the same regardless of the magnification position.

An impeller 52 is attached to the output shaft of the motor 25. A horseshoe-shaped photoelectric sensor 53 is attached to the impeller 52. The photoelectric sensor 53 is
The rotation angle of the motor 25 is detected, and a pulse signal corresponding to the rotation angle is sent to the control unit 40. The control unit 40 counts the pulse signal obtained from the photoelectric sensor 53 during the focus control, compares the pulse signal with the number of pulses read from the ROM 51, and stops driving the motor 25 when they match.

At the time of focus control, the control unit 40 drives the motor 25 to drive the drive ring 1 within the focusing range within the gap.
Rotate 4. Within this range, the taking lens is focused at infinity, at the closest distance, and at an arbitrary focus position therebetween. The focus position with respect to the rotational position of the drive ring 14 is, for example, the fork portion 30 shown in FIG.
1, the front lens group 13 retreats to focus on an infinite focus position, and the left end of the fork 30 approaches the left end wall 31a of the notch 31. When the front lens 13 is in the depressed position, the front lens group 13 moves forward to focus on the closest focus position. Therefore, in this example, the range of the gap is a range longer than the focusing range.

When the variable power control is changed from the wide end to the tele end, the movable cylinder 11 rotates in a direction in which the fork 30 presses the left end wall 31a of the notch 31, and conversely, the tele end. When moving toward the wide end, the movable cylinder 11 rotates in a direction in which the fork portion 30 presses the right end wall 31b of the notch portion 31. Since focusing is performed after zooming, the fork 30 is started from a state in which the fork 30 is in contact with either the left end wall 31a or the right end wall 31b of the notch 31. However, in this case, since the focusing start position differs depending on the zoom variable direction, there is a possibility that an error may occur in the zooming direction even at the same zooming and focusing position. Therefore, in this example, a focus origin switch 54 for detecting the origin position of the drive ring 12 with respect to the rotational position of the driven ring 12 is provided between the drive ring 14 and the driven ring 12, and after the magnification is changed, The drive ring 14 is rotated backward until the origin position is detected by the focus origin switch 54, and then the drive ring 14 is rotated within the range of the gap to perform focusing.

The focus origin switch 54 is composed of a connection terminal 55 and a conductive and elastic plate spring 56 which comes into contact with the connection terminal 55. On the outer periphery of the switch 54, there are provided ribs 5 protruding from the outer periphery of the driven ring 12.
7 is located. The focus origin position is determined between a position where the fork portion 30 contacts the right end wall 31b of the notch portion 31 and an infinity focus position within a focusing range from now on. The leaf spring 56 is rotated to the position retracted from the outer surface of the spring 56 to connect the leaf spring 56 to the connection terminal 5.
5 and the focus origin switch 54 is turned on. An arc-shaped sliding pattern 58 provided on the front surface of the rectilinear cylinder 11 and a brush 59 slid on the sliding pattern 58 and provided on the drive ring 14 are provided with a signal obtained from the focus origin switch 54. Is transmitted to the control unit 40 in the camera body.

As shown in detail in FIG. 4, a pair of switches 45 and 46 for the control unit 40 to detect the wide-angle end and the telephoto end of the variable power position are arranged on the front surface of the rectilinear barrel 15. I have. The signals obtained from these switches 45 and 46 are monitored by the control unit 40. this house,
At the wide end of the zoom lens, the switch 45 at the wide end is used.
The right side wall 29a of the sector gear 29 of the drive ring 14 abuts on the switch ring 45 to turn on the switch 45. When the wide end switch 45 is turned on, the control unit 40 determines that the wide end has been reached. When the control unit 40 recognizes the wide end, the variable power driving of the motor 25 in the wide end direction is stopped.

At the telephoto end of the zoom lens, the left side wall 29b of the sector gear 29 abuts on the switch 46 at the telephoto end to turn on this switch. Therefore, the control unit 40 recognizes that the telephoto end has been reached. When the control unit 40 recognizes the telephoto end, the motor 25 stops the variable power driving in the telephoto end direction.

The operation of the above configuration will be described. Lens group 1
It is assumed that the initial states of 3 and 16 are in the state of the wide position shown in FIG. In this state, the relative positional relationship between the drive ring 14 and the driven ring 12 is as shown in FIG. 4, that is, the right side wall 29a of the sector gear 29 is
, And the rotational position of the drive ring 14 is the focus origin position. Thereby, the control unit 40
It is recognized that the lens groups 13 and 16 are at the wide end and at the focus origin position.

When the shutter button 49 is half-pressed, the control section 40 operates the distance measuring mechanism 50 to measure the object distance. Then, from the obtained subject distance information, R
Based on the feed pulse comparison table stored in the OM 51, the number of feed pulses to the in-focus position according to the subject distance information at this time is calculated. Thereafter, the motor 25 is driven to rotate forward to count the number of pulses obtained from the photoelectric sensor 53. When the counted value reaches the previously calculated number of pulses, the motor 2 is driven.
5 is stopped.

The drive of the motor 25 during this time is transmitted to the drive ring 14 via the reduction gear train 60, the drive gear 24, and the gears 23, 26, and 28, and the fork 30 is turned counterclockwise inside the notch 31. Rotate toward. Since the projection 38 of the front lens frame 13 is engaged with the fork 30 in the rotation direction about the optical axis 20, the drive ring 1
The front lens frame 13 rotates together with 4, and these rotate relative to the driven ring 12. As a result, the front lens group frame 13 moves along the direction of the optical axis 20 according to the leads of the helicoids 36 and 37. When the motor 25 is driven by the amount of the feed pulse, the focus of the photographing lens is adjusted to the subject distance. At this time, the driving ring 14 rotates relative to the driven ring 12, and the rib 57 pushes the leaf spring 56 to separate the leaf spring 56 from the connection terminal 55.
FF is performed.

When the photographer performs a half-press operation to a full-press operation, the control unit 40 operates the shutter mechanism. In addition,
The control unit 40 detects the magnification position based on the signal obtained from the brush 48 at this time, and determines the F value of the photographing lens from this magnification position and uses it for exposure control. After the completion of the exposure, the control unit 40 drives the motor 25 in the reverse direction. This drive causes the drive ring 14 to rotate clockwise in FIG. During this time, the control unit 40 monitors the signal of the focus origin switch 54,
When the switch 4 is turned on, the driving of the motor 25 is stopped. Thereby, the rotational position of the drive ring 14 returns to the focus origin position shown in FIG. Note that, even when the half-press operation of the shutter button 49 is released, the control unit 40 continues to operate the motor 2.
5 is reversely driven to always return the rotational position of the drive ring 14 to the focus origin position.

Next, when the tele-side zoom button 41a is operated, the control unit 58 drives the motor 25 to rotate forward in response to the operation time. The driving of the motor 25 during this time is as follows.
As described above, the power is transmitted to the drive ring 14 and the fork 3
0 rotates in the notch 31 in the counterclockwise direction. Then, the driving of the motor 25 is continued, and as shown in FIG.
a. Then, the rotation of the drive ring 14 causes the fork portion 30 to move to the left end wall 31 a of the notch portion 31.
, The driven ring 12 is rotated. The rotation of the driven ring 12 is transmitted to the moving cylinder 11,
The moving cylinder 11 has a helicoid 18, 1 between the moving cylinder 11 and the fixed cylinder 10.
9, the front lens frame 13 and the rear lens frame 16 are moved together, and the rear lens frame 16 is moved relative to the front lens frame 13 by the displacement of the cam groove 34. Move relatively.

After the operation of the tele side zoom button 41a is completed and the zoom position is set to an arbitrary magnification position, the control unit 40 drives the motor 25 in the reverse direction and the focus origin switch 54 is turned on, as described above. By performing focus origin control for stopping the reverse rotation drive of the motor 25, the drive ring 14 is stopped.
Return the rotation position of to the origin position. Thereafter, as described above, focusing is performed by half-pressing the shutter button 49,
Exposure is performed by performing a full-press operation as it is.

The operation of the tele side zoom button 41a is performed again, and the drive ring 14 is rotated to the position where the left end wall 29b turns on the switch 46, whereby the drive of the motor 15 is stopped, as shown in FIGS. 3 and 6. It becomes the state of the tele end. Thereafter, focus origin control is performed, and the rotational position of the drive ring 14 is returned to the origin position.

When the shutter button 49 is half-pressed, the motor 25 is rotated forward as described above, and the drive ring 14 is rotated by the amount that the fork 30 moves inside the cutout 31. The front group lens frame 13
Is moved to a focus position corresponding to the subject distance. After the completion of the exposure, the driving ring 14 is again driven by the reverse rotation of the motor 25.
Is returned to the origin position.

Next, when the wide zoom button 41b is operated, the motor 25 is driven to rotate in the reverse direction. With this drive,
The drive ring 14 rotates clockwise, and the fork 30 contacts the right end wall 31 b of the cutout 31. The driven ring 12 rotates together with the rotation of the drive ring 14 after the contact. As a result, the movable cylinder 11 is
2 and zooming from the telephoto end to the wide end is performed. The operation of the zoom button 41b is terminated,
After the arbitrary zoom position is set, focus origin control is performed again. At the time of zooming from the telephoto end to the wide end, since the fork portion 30 is in contact with the right end wall 31b of the cutout portion 31, the focus origin switch 54
Is turned on. For this reason, in the focus origin control at the time of zooming from the telephoto end to the wide end, as shown in FIG.

When the focus origin switch 54 is turned off,
Then, the drive ring 14 is rotated to a position at which the drive ring 1 is turned to the position where the focus origin switch 54 is turned on.
4, the rotation position at which the focus origin switch 54 is turned on may be set as the origin position of the drive ring 14 in the same manner as the focus origin control after the magnification is changed from the wide end to the tele end.

In the above embodiment, the moving cylinder 11 and the driven ring 12 are separately provided and fixed by screws, but the present invention is not limited to this, and the moving cylinder 11 and the driven ring 12 May be provided integrally.

In the above embodiment, the drive ring 14
The front lens frame 13 and the front lens frame 13 are separately provided, and these are engaged with each other by the fork portion 30 and the protruding portion 38 in the rotation direction around the optical axis 20. These engagement structures are known structures. Anything is fine. Further, the drive ring 14 and the front group lens frame 13 may be formed integrally. In this case, it is necessary to support the drive ring 14 movably along the direction of the optical axis 20, and to increase the tooth width of one of the gear 28 and the sector gear 29 in the direction of the optical axis 20. Therefore, it is necessary to prevent the meshing from being released even if the drive ring 14 moves together with the front group lens frame 13.

Further, in the above embodiment, the front group lens frame 13 is moved by the helicoids 36 and 37 at the time of focusing. Instead, a cam is used to move the front group lens frame 13.
May be moved.

[0038]

As described above, in the zoom lens apparatus according to the present invention, the drive ring is rotated beyond the range of the gap, and the two lens groups are moved by rotating the movable cylinder together with the drive ring to change the magnification. At the time of focusing after this zooming, by rotating the drive ring within the gap,
Since only the drive ring is rotated while the moving cylinder is in the rotation stopped state, only the front group lens is moved so that focusing can be performed. Can be used as In addition, since the lens moving means for zooming and the lens moving means for focusing can be separately provided as compared with those described in the prior art, the zoom speed can be increased.

According to the second aspect of the present invention, a male helicoid is formed on the outer periphery, and a drive ring integrally including a front group lens frame for holding the front group lens and a female helicoid engaged with the male helicoid are formed on the inner circumference. Since the movable cylinder integrally formed with the formed driven ring is provided and the front lens group is moved in accordance with the lead of the helicoid, the structure is simplified, and the cost and size of the apparatus can be reduced. .

[Brief description of the drawings]

FIG. 1 is an exploded perspective view schematically showing a zoom lens device according to the present invention.

FIG. 2 is a cross-sectional view showing a state of a zoom lens device at a wide end.

FIG. 3 is a cross-sectional view illustrating a tele end state of the zoom lens device.

FIG. 4 is a longitudinal sectional view showing a state of a zoom lens device at a wide end.

FIG. 5 is a longitudinal sectional view showing a state in which the zoom lens device is zoomed from a wide end to a telephoto end.

FIG. 6 is a longitudinal sectional view showing a state at a telephoto end of the zoom lens device.

FIG. 7 is a longitudinal sectional view showing a state in which the rotational position of the drive ring is returned to the original position after zooming from the telephoto end to the wide end.

[Explanation of symbols]

 Reference Signs List 10 fixed cylinder 11 moving cylinder 12 driven ring 13 front group lens frame 14 drive ring 15 rectilinear cylinder 16 rear group lens frame 17 rectilinear guide frame 18, 19, 36, 37 helicoid 30 fork 31 cutout 38 projection

Claims (2)

[Claims] 1. A magnification change is performed by moving at least a front lens group and a rear lens group in an optical axis direction using rotation of a single motor, and changing a distance between the lens groups. Then, in a zoom lens device that performs focusing by moving the front lens group in the optical axis direction in the zoom state, the motor is driven to rotate around the optical axis to move the front lens group in the optical axis direction. A drive ring, the front group lens and the rear group lens are built-in, and the drive ring is connected to the drive ring with a gap in the rotation direction. When the drive ring rotates beyond the range of the gap, the rotation is used. A moving cylinder which is placed in a stopped state when the driving ring rotates within the gap, and the rotation about the optical axis is stopped. Use rotation The magnification is changed by changing the distance between the two lens groups using
In addition, by rotating the drive ring within the gap, the drive ring rotates relative to the movable barrel to move the front lens group in the optical axis direction to perform focusing. Zoom lens device. 2. The drive ring has a male helicoid formed on the outer periphery thereof, integrally has a front group lens frame for holding the front group lens, and the movable barrel has a female engaging with the male helicoid. A driven ring having a helicoid formed on the inner periphery is integrally formed, and by rotating the driving ring in the gap, the driving ring rotates relative to the moving cylinder and is connected to the lead of the helicoid. 2. The zoom lens apparatus according to claim 1, wherein the front lens is moved in the optical axis direction.