JPH01167814A - Variable focus lens drive device - Google Patents

Abstract

PURPOSE:To obtain a miniaturized high accuracy driving device driving a 2nd group lens frame by simple constitution by driving said lens frame by variable power in response to the difference between a barrel frame and a 1st group lens frame. CONSTITUTION:The 1st group frame 6 supporting a 1st lens group 5 is supported movably in the direction of an optical axis in the barrel frame 4 movable along guide axes 24-26 fixed to a fixed frame 1. The 2nd group frame 7a supporting a 2nd lens group 7 is supported in a 2nd group frame cam 9 driven by the 1st group frame 6 so that the frame 7a can advance and retreat. When the barrel frame 4 is advanced and retreated by a motor 11, the 1st group frame 6 is advanced and retreated by driving screws 21-24. The 2nd group frame 7a is advanced and retreated in response to the difference between the moving amount of the 1st group frame 6 and that of the barrel frame 4 through the cam 9. As a result, the miniaturized, high accuracy driving device capable of driving the 2nd group frame by its simple expedient can be obtained.

Description

Detailed Description of the Invention (a) Technical Field The present invention relates to a driving device for a variable focus lens, and more particularly, the present invention relates to a driving device for a variable focus lens, and more specifically, a driving device for a variable focus lens, in which at least a first lens group and a second lens group are arranged on the same optical axis. , a variable-focus lens that performs a zooming operation of driving the first and second lens groups by a predetermined amount in order to change the focal length of a variable-focus lens consisting of a variable-focus optical system using the first lens group as a focusing lens. The present invention relates to a focusing lens driving device.

(b) Prior art In recent years, cameras have become more electronic and motorized, and so-called variable-focus cameras have become available, in which the focal length of the photographic optical system can be changed steplessly or to multiple settings with one-touch operation by driving a motor or the like. However, conventionally, the rotation of a cam ring in which a cam groove is drilled drives (moves) a lens frame in which a cam pin that is slidably fitted into the cam groove is implanted in the optical axis direction. ) to change the focal length.

However, although such conventional devices have the advantage of having a relatively simple configuration, the manufacturing cost of the cam ring is high, and the length of the cam ring in the optical axis direction cannot be shortened, resulting in This was a factor that prevented the lens barrel from becoming more compact.

In order to solve this problem, the inventors divided the lens barrel into a plurality of frames, and created a lens barrel frame within the fixed frame, and a first lens barrel frame within this lens barrel frame.
A first group frame supporting the lens group, and a second group frame within this first group frame.
We have devised a configuration in which the second group frames supporting the lens groups are respectively movable along the optical axis direction and are moved forward and backward.

However, when configured in this way, a problem arises as to what is the appropriate means for driving the second group frame.For example,
The simplest method would be to drive directly from a motor or the like as a drive source disposed on the fixed frame via a deceleration mechanism, but since the amount of movement of the second group frame relative to the fixed frame is unexpectedly large, Inevitably, the drive mechanism is large and complicated, and adjustment of the gear ratio is troublesome. Furthermore, when transmitting the driving force from the fixed frame to the second group frame arranged inside the lens barrel frame, the lens barrel frame corresponds to the sum of the relative movement of the first group frame and the lens barrel frame. A problem arises in that it is difficult to accommodate changes in the amount of movement of the lens barrel frame.

Furthermore, as disclosed in Japanese Patent Application Laid-open No. 60-79314, there is a lens frame in which the lens frame is driven in the optical axis direction by a single drive screw instead of the cam ring. Not only is there a problem in that it is difficult to move the lens smoothly because of the concentration of There was a problem that they could no longer perform effectively. In other words, there was a problem in that the posture of the lens became unstable as it moved.

(c) Purpose The present invention has been made in view of the above-mentioned circumstances, and its purpose is to drive the second group frame with an inexpensive and simple configuration, thereby widening the variable range of focal length (variable magnification). An object of the present invention is to provide a variable focus lens driving device that is compact, highly accurate, and inexpensive to manufacture despite having a relatively wide range.

(d) Structure In order to achieve the above-mentioned object, the present invention includes at least a first lens group and a second lens group arranged on the same optical axis, and the first lens group is used as a focusing lens. In a variable focus lens driving device that performs a magnification change operation in which each of the first and second lens groups is driven by a predetermined amount in order to change the focal length of a variable focus lens consisting of a variable focus optical system, a fixed frame fixed to a fixed part of the optical device;
A lens barrel frame movably supported along the optical axis inside the fixed frame, and the first lens group supported so as to be capable of focusing, are mounted inside the lens barrel frame. a first group frame supported so as to be movable parallel to the optical axis;
a movement amount detection unit that detects the amount of movement of the group frame in the optical axis direction with respect to the lens barrel frame; a motion converter that converts the amount of movement into a rotation amount; and a motion converter that causes the first group frame to rotate about the optical axis. a variable power cam that is freely supported and rotationally driven by the motion converter in accordance with the amount of movement; and a variable power cam that is driven while being regulated by the variable power cam while fixedly supporting the second lens group. A second group frame movable along the optical axis, a drive section such as a motor that serves as a drive source for performing the zooming operation, a transmission mechanism section that transmits the driving force from the drive section, and the transmission mechanism. A state in which the lens barrel frame and the first group frame are each driven by a predetermined amount by a mechanism, and the members of the lens barrel frame and the first group frame that should be perpendicular to the optical axis are held substantially at right angles. at least 3 to move each parallel to the optical axis direction.
The second group frame is driven to change the magnification by the differential movement between the lens barrel frame and the first group frame, and the first lens group and the second lens group are rotated according to a schedule. This feature is characterized in that the lens is positioned in a positional relationship corresponding to the focal length of the lens.

Embodiments of the present invention will be specifically described below with reference to the accompanying drawings.

FIG. 1 is a partially cutaway perspective view showing the overall configuration of an embodiment of a variable focus lens driving device according to the present invention.

In Figure 1, 1 is a stationary part such as a camera (for example, the front plate)
3 is an optical axis that passes through the approximate center of the fixed frame 1, and 1a and 1b are the ends of the fixed frame 1 on the subject side and film side (none of which are shown), respectively. A front plate and a rear plate provided approximately at right angles to the axis 3, l
Reference characters c and 1d are formed by hollowing out the front plate 1a and the rear plate 1b into a rectangular shape, respectively, and are a front window through which a lens barrel frame (to be described later) is inserted (advanced and retreated) and a rear window through which a photographing light flux passes.

2 is arranged at the position of this rear window 1d on the optical axis 3,
This is a third lens formed so that the upper and lower and left and right peripheral portions are planes parallel to the optical axis 3.

The lens barrel frame 4 is disposed inside the fixed frame 1 and is movably supported along the optical axis 3, and 48 to 4c all constitute the lens barrel frame 4. , 4a is a box-shaped lens barrel arranged with its center aligned with the optical axis, and 4b is slightly larger than the cross section (hereinafter referred to as "cross section") perpendicular to the optical axis 3 of this lens barrel 4a. A lens barrel first substrate 4c, which is made of a plate-shaped member and is connected to the rear end of the lens barrel 4a at a substantially right angle to the optical axis 3, is maintained at a small distance behind the lens barrel first substrate 4b. The second lens barrel substrate 4b is formed in substantially the same manner as the first lens barrel substrate 4b, and hereinafter, the first lens barrel substrate 4b and the second lens barrel substrate 4c will be collectively referred to as the lens barrel substrate 4d. There is.

5 is a lens group 5a as a first lens group disposed on the side closest to the subject (not shown) on the optical axis 3;
6 is a cylindrical lens frame that fixedly supports the lens group 5, and 6 is a lens frame 6 that is moved in parallel to the optical axis 3 within the lens barrel frame 4 while supporting the lens frame 5a inside thereof. The first group frames 6a, 6b, and 6c that can be supported constitute the first group frame 6, and among these, 6a is a rectangular tube section along the optical axis 3 and has a rectangular cross section, and 6b is a tube section that is rectangular in cross section. This cylindrical part 6a
A first group substrate 6c, which is connected to the rear end and is made of a plate-shaped member having an area slightly larger than the cross section of the cylindrical portion 6a, extends rearward from the edge of the first group substrate 6b at a substantially right angle. This is a connected gear support part.

The first lens group 5 (the first lens frame 5a) moves integrally with the movement of the first group frame 6. (not shown) so that it moves independently of the first group frame 6 and functions as a focusing lens.

7 is a second lens group disposed behind the lens group 5 on the optical axis 3, and 7a is coaxial with the optical axis 3 that fixedly supports the second lens group 7. A cylindrical second group frame 7b fixedly supported on the second group frame 7a is implanted in a direction perpendicular to the optical axis 3 on the outside of the second group frame 7a, and a cam pin 7c that comes into contact with a cam surface to be described later is similarly a second group frame 7a. A slider 7d having a fork-shaped portion attached to the outer periphery of the second group frame 7a to prevent rotation of the second group frame 7a and guide movement in the three directions of the optical axis.
is a spring hook also planted on the outer periphery of the second group frame 7a,
8 is a rod-shaped second group frame guide fixed to the first group frame 6 (more specifically, the first group board 6b) and slidably fits into the fork-shaped portion of the slider 7c; 9 is a rod-shaped second group frame guide at both ends; It consists of an open cylindrical member, with the second group frame 7a fitted into the inner periphery,
For variable magnification, the outer periphery is fitted into a hollow bearing portion bored in the center of the first group substrate 6b, and is supported rotatably around the optical axis 3 without moving in the direction of the optical axis 3. A second group frame cam serving as a cam, 9a is a cam surface provided on the front edge of the second group frame cam 9 and makes sliding contact with the cam pin 7b, and 9b is fixed to the rear end of the second group frame cam 9. It's a crown gear. Reference numerals 10a and 10b are second group springs which are stretched between the cam pin 7b and the spring hook 7d and the first group substrate 6b with tension applied thereto.

11 is a motor as a drive unit; 12 is a reduction gear 12a driven by a driving gear lla of the motor 11;

12b, both of which are arranged on the fixed frame 1. Reference numeral 13 has an oval-shaped hole in the center and is a drive gear driven by the motor 11 via the reduction gear train 12. Reference numeral 13a has an oval-shaped hole in the center, and 13a is a drive gear that is inserted into a bearing hole drilled in the lens barrel substrate 4d. are rotatably supported by the front plate 1a and the rear plate 1b of the fixed frame 1, respectively, and the oval-shaped hole of the drive gear 13 is fitted and fixed into the rear end of the rear plate 1b. This is a drive shaft made of a rod-shaped member parallel to the optical axis 3 of. 13b is sandwiched between the lens barrel first substrate 4b and the lens barrel second substrate 4c, and has an oval-shaped insertion hole, into which the drive shaft 13a is inserted, and the rotational force of the drive shaft 13a is This is a moving gear that is configured to be able to move integrally with the lens barrel substrate 4d in the direction of the optical axis 3 under the action of a drive screw to be described later.

14a, 14b, 14c, 15, 16a.

16b, 16c, 17a, 17b, and 17c are gears rotatably sandwiched between the lens barrel first substrate 4a and the lens barrel second substrate 4b;
16a, 16b, 1c are two-stage gears each having a gear with a small diameter connected to the front side of both end faces.
6c, 17a, 17b.

17c has a female thread screwed into a hole drilled in the center. 14a is a transmission gear that meshes with the moving gear 13b; 15 is an annular gear that meshes with this transmission gear 14a and has a large circular hole formed in the center so that a photographing light beam can pass; 14b and 14c; 16a, 16b, 16c are transmission gears that mesh with the annular gear 15; first group drive gears 17a, 1 that mesh with small diameter gears of the transmission gears 14a, 14b, 14c, respectively;
7b.

17c are the transmission gears 14a and 14b, respectively.

This is a lens barrel drive gear that meshes with 14c.

In addition, the above-mentioned transmission gears 14a and 14b will be referred to below.

14c collectively as the transmission gear 14 and the first group drive gear 1.
6a, 16b, and 16c together as the first group drive gear 1
6. Lens barrel drive gears 17a, 17b.

17c may be collectively referred to as lens barrel drive gear 17.

Further, the transmission gear 14, the annular gear 15, the lens barrel drive gear 17, and the first group drive gear 16 constitute a transmission mechanism section.

18 is supported by the peripheral edges of the rear plate 1b and the front plate 1a with both end portions 18a and 18b non-rotatably and with a slight play, and has a right-hand thread, for example, over almost the entire length thereof, and is connected to the lens barrel drive gear 17a. Similarly, lens barrel drive screws 19 are parallel to the optical axis 3 and are screwed together with the above-mentioned female screws, respectively at both ends 19a.

19b is non-rotatably supported by the fixed frame 1, and the lens barrel drive gear 1
A lens barrel drive screw 20 is similarly screwed into the female thread of the lens barrel drive gear 17c;
1, 22, and 23 have their front ends connected to the first group board 6b.
The first group drive gear 16a has a slight play at the peripheral edge of the first group drive gear 16a, which does not rotate but is supported without coming off from the first group board 6b, and has, for example, a left-hand thread threaded therethrough over almost its entire length. 16b and 16c are first group drive screws that are substantially parallel to the optical axis and are screwed into the female screws of 16c, respectively.

The lens barrel drive screws 18 to 20 and the first group drive screws 21 to 23 each constitute three drive screws.

24, 25 and 26 are respectively inserted into guide holes drilled in the peripheral edge of the lens barrel substrate 4d, and are approximately parallel to the optical axis 3, with their front and rear ends forming the front plate 1a and the rear plate 1b, respectively. (that is, the guide shaft fixed to the fixed frame 1).

Lens barrel springs 27 and 28 are coil springs inserted under compressive force between the lens barrel substrate 4d and the rear plate 1b of these guide shafts 25 and 26 (although not shown, the guide shafts 24 also have coil springs). (also provided).

Reference numerals 29 to 31 designate first group springs that are stretched between the first group substrate 6b and the cam first substrate 4b by applying a tensile force.

32 is a lens barrel rack that is parallel to the optical axis 3 and located slightly inward from the side wall (not shown) of the lens barrel 4a, and extends forward from the front surface of the lens barrel first substrate 4b; 33 is a gear; The cam drive gear train 33a disposed on the support portion 6c constitutes the first stage of the cam drive gear train 33.

A pinion 33b that meshes with the lens barrel rack 32 constitutes the final stage of the gear train 33, and is a connecting gear that meshes with the crown gear 9b.
3a constitutes a movement amount detection section, and the coupling gear 33b and crown gear 9b constitute a momentum conversion section.

Although not shown in the drawings, a plurality of guide shafts parallel to the optical axes 3 fixed to the lens barrel frame 4 are inserted into, for example, guide holes bored in the peripheral portion of the first group substrate 6b. It is configured to guide (position control) the movement of the first group frame 6 in the optical axis direction.

Further, the lens group 5, the second lens group 7, and the third lens 2 constitute a variable focus optical system.

Moreover, the state shown in FIG. 1 shows a telephoto state in which the focal length is set to the long focal length side.

Further, one of the lens barrel drive gear 17 and the first group drive gear 16
The rotation is caused by lens barrel drive screws 18 to 20 and first group drive screw 2.
It corresponds to one pitch from 1 to 23.

In addition, in the drawings from FIG. 2 onwards, the same members as those in FIG.

FIG. 2 shows a transmission path of the driving force (rotational force), and is a schematic diagram of the transmission mechanism section viewed from the rear side of the optical axis 3.

FIG. 3 is an enlarged longitudinal cross-sectional view of a part of the transmission mechanism of FIG. 1, for example, the first group drive gear 16b.

In FIG. 3, 34 is a male threaded portion of the first group drive screw 22, 35 is a female threaded portion of the first group drive gear 16b, and 36 is a first
A step portion 37 reduces the frictional force received from the lens barrel substrate 4d due to the thrust force generated in the group drive gear 16b.
The teeth of the group drive gear 16b, 38 are the first group drive gear 16b.
This is a cylindrical shaft portion that protrudes in a cylindrical shape from the center of both end surfaces.

FIG. 4 is an enlarged perspective view showing in detail the configuration of both ends of the barrel drive screw 19 in FIG. 1, for example, as a representative example.

In FIG. 4, 39 is a threaded portion into which the male thread of the barrel drive screw 19 is screwed, 39a and 39b are rear and front end surfaces of the threaded portion 39, respectively, and 40a and 40b are integrated with the end surfaces 39a and 39b, respectively. The oval shafts and round shafts 41a and 41b, which are connected to each other, are bored in the rear plate 1b and the front plate 1a in a shape similar to that of the oval shaft 40a and round shaft 40b, and slightly larger than the outer diameter thereof. This is the support hole.

It should be noted that the lengths of the oval shaft 40a and the round shaft 40b are exaggerated in order to make the configuration easier to understand. In addition, in the actual assembled state, the front plate 1a is in sliding contact with the end surface 39b,
The rear plate 1b is disposed at a position in sliding contact with the end surface 39a, and the lens barrel drive screw 19 is precisely regulated in its axial position at each end 19a and 19b, and has a small degree of freedom in the circumferential direction. It is composed of

FIG. 5 is an enlarged longitudinal sectional side view showing in detail the configuration of the end portion of the first group drive screw 22 in FIG. 1 on the side supported by the first group board 6b, for example.

In FIG. 5, 42 is a threaded portion of the first group drive screw 22;
Reference numeral 43 denotes an end surface of this threaded portion 42, 44 a shaft portion formed from this end surface 43 to the shaft end with a diameter smaller than that of the threaded portion 42, and 45 a first group substrate 6 into which this shaft portion 44 is inserted.
The support hole 46 drilled in b is an E-ring fitted into a circumferential groove formed in a portion of the shaft portion 44 protruding from the first group substrate 6b. Note that the E ring 46 is attached to the first group substrate 6.
b, and is disposed in sliding contact with or very close to the support hole 45.
The inner diameter of the shaft portion 44 is slightly larger than the outer diameter of the shaft portion 44 and has a slight degree of freedom in the diametrical direction, and its position in the axial direction is regulated by the end surface 43. The structure is such that the shaft portion 44 does not come off from the substrate 6b.

6 to 8 are longitudinal sectional side views schematically showing the three operating modes of the present embodiment shown in FIG. 1, and FIG. 6 shows the stored state when not in use, and FIG. 8 shows the wide-angle state in which the focal length is switched to the short focal length side, and FIG. 8 shows the above-mentioned telephoto state.

In FIGS. 6 and 7, 47 is an object located in front of the lens group 5, and 48 is a film surface located behind the third lens 2. Note that 5a is the third lens 2 and the first
As mentioned in the explanation of the figures, the relative position with respect to the first group frame 6 is changed by the focusing mechanism section, which is not directly fixed to the first group frame 6 but is fixed to the first group frame 6. It is supported by the first group frame 6 in such a manner that it can be seen. Therefore, when the focusing mechanism is not in operation, it moves integrally with the first group frame 6, and when the focusing mechanism is in operation, it moves along the optical axis 3 independently of the first group frame 6. It is configured to be movable.

9 to 11 are side views schematically showing the operational relationship between the first group frame 6 and the second group frame 7a. Of these, FIG. 9 shows the telephoto state, and FIG. 10 shows the wide state. , and FIG. 11 respectively show the stored state.

In addition, in these figures, in order to make it easier to understand the correspondence relationship between the cam surface 9a and the second group frame 7a, the illustrations are based on the second group frame cam 9, but in reality, the second group frame cam 9 is shown as a reference. As mentioned in the explanation, it is the second group frame cam 9 that rotates.
It is the second group frame 7a that moves linearly with respect to the optical axis 3.

In FIGS. 9 to 11, 49 is a protruding member extending rearward from the second group frame 7a along the optical axis 3, and its length is a part of the fixed frame 1 in the wide state. It is configured to be at a position immediately before contacting the stopper portion 1e.

12 and 13 show the operation of the second group drive section consisting of the lens barrel rack 32, cam drive gear train 33, and second group frame cam 9, which are essential parts of the present invention, and the fine details of the lens barrel rack 32. This is a schematic side view of the lens barrel rack 32 from the position of the optical axis 3 in FIG. 1 to explain the fine adjustment mechanism that performs adjustment. The magnification change operation.

FIG. 13 shows the magnification changing operation from the telephoto state to the wide state. In Figures 12 and 13, 5
o is a rack body that meshes with the pinion 33a, 51 is a mounting hole formed in the rack body 50 and is an oblong hole long in the optical axis direction, and 52 is a mounting hole that is substantially perpendicular to the lens barrel first substrate 4b and faces forward. This rack support part 52 has a mounting screw hole in which a female thread is screwed at a position corresponding to the above-mentioned mounting hole 51. 52a is a mounting screw which is screwed into this female screw and which attaches and fixes the rack main body 5o to the rack support part 52, so that the rack support part 52 and the rack main body 50 constitute the lens barrel rack 32 described in FIG. There is.

Arrows 53 and 54 indicate the direction in which the first group frame 6 moves away from and approaches the lens barrel frame 4 (more specifically, the lens barrel rack 32), respectively.

Although omitted in the explanation of FIG. 1, the cam drive gear train 33
The gear ratio is set based on various factors such as the distance between the shafts of the pinion 33a and the connecting gear 33b, the pressure angle of the cam surface 9a, and the rotation angle required by the second group frame cam 9.

Before explaining the operation of the fine adjustment mechanism section, the second
The operation of the group driving section will be briefly explained. The case where the first group frame 6 moves in the direction of the arrow 53 as shown in FIG. 12 will be described. Rack body 50 (that is, lens barrel rack 32)
The pinion 33a that meshes with rotates clockwise, which is sequentially transmitted to the cam drive gear train 33, and the connecting gear 33b rotates counterclockwise. The crown gear 9b that meshes with this moves downward in the figure, and the second group frame 7a moves toward the cam surface 9.
It will protrude forward due to a. Since the concept is the same for FIG. 13, the explanation will be omitted.

Now, the operation of the fine adjustment mechanism section will be explained here.

For example, while maintaining the positional relationship between the first group frame 6 and the lens barrel frame 4 (not shown here, the lens barrel rack 32 integrated with this) in the wide state shown in FIG. When the mounting screw 52a is loosened and the rack body SO is moved by a minute amount to the left and right in the figure, the second frame cam 9 rotates a minute amount, and the second frame 7a moves forward and backward by a minute amount. 7a coincides with a predetermined reference position, the rack body 50 is tightened and fixed to the rack support portion 52 with the mounting screw 52a.

The operation of this embodiment configured in this way will be explained.

First, the rotational force transmission operation will be explained with reference to FIGS. 1 and 2. For example, if the drive gear lla of the motor 11 rotates clockwise, the drive gear 13 rotates counterclockwise via the reduction gear train 12, and this rotational force is applied to the drive shaft 1.
3a to rotate the moving gear 13b counterclockwise. The transmission gear 14a that meshes with this moving gear 13b rotates clockwise, the annular gear 15 that meshes with this rotates counterclockwise, and the transmission gears 14b and 14 that mesh with this rotate.
c rotates clockwise. That is, three transmission gears 1
4 all rotate clockwise. The three lens barrel drive gears 17 and the three first group drive gears 16 that mesh with these transmission gears 14, respectively, rotate counterclockwise. In other words, the driving gear lla of the motor 11
The lens barrel drive gear 17 and the first group drive gear 16 rotate in opposite directions.

Now, the short focus switching operation from the telephoto state shown in FIGS. 1, 8, and 9 to the wide state shown in FIGS. 7 and 10 will be described. As described above, when the lens barrel drive gear 17 and the first group drive gear 16 rotate counterclockwise, the lens barrel drive screws 18 to 20 that are screwed into the respective female threads of the lens barrel drive gear 17 are rotated to the right. If screws are used, the barrel drive screws 18 to 20 cannot move or rotate in the axial direction, so the barrel drive gear 17 itself moves toward the rear of the optical axis 3 while rotating. Along with this movement, the lens barrel substrate 4d,
That is, the lens barrel frame 4 is connected to the lItm springs 27 and 28.
Resisting the urging force of , it begins to retreat while being guided by the guide shafts 24 to 26 .

On the other hand, if the first group drive screws 21 to 23 that are screwed into the respective female screws of the first group drive gear 16 are left-handed threads, the first group drive gear 16 itself tries to move forward, but the lens barrel substrate 4d
Since the position in the optical axis direction is regulated by
The group drive screws 21 to 23 move toward the rear of the optical axis 3. That is, the first group frame 6 begins to move backward while being guided by a guide shaft (not shown) by the urging force of the first group springs 29 to 31.

In other words, the first group frame 6 is located in the lens barrel frame 4 that is retreating with respect to the fixed frame 1, and further moves relative to the lens barrel frame 4 to retreat.

Now, by this relative movement, that is, by moving the first group board 6b in the direction approaching the lens barrel board 4d, the gear support part 6c retreats with respect to the lens barrel rack 32 and engages with the lens barrel rack 32. The pinion 33a rotates counterclockwise. This rotation is transmitted via the cam drive gear train 33, rotates the connecting gear 33b clockwise, and the connecting gear 33b
The crown gear 9b that meshes with rotates counterclockwise, causing the second frame cam 9 to rotate counterclockwise. The cam pin 7b that comes into sliding contact with the cam surface 9a due to this rotation is pulled rearward by the second group springs 10a and 10b, so that the cam surface 9a
It tries to move diagonally backward along the slope of a, but the second
Since the sub-frame 7a is only allowed to move linearly in the optical axis 3 direction by the slider 7c and the second sub-frame guide 8, it ends up moving rearward in parallel to the optical axis 3.

When these operations further progress and the cam pin 7b reaches the wide position (approximately V-shaped portion) of the cam surface 9a as shown in FIG. 10, it protrudes rearward from the first group board 6b of the second frame 7a. The amount of rearward protrusion becomes maximum, and the protruding member 49 reaches just before the stopper portion 1e of the fixed portion 1. That is, as shown in FIG. 7, the front end of the lens barrel frame 4 (more specifically, the lens barrel 4a) is slightly extended from the front window 1a of the fixed frame 1,
More specifically, the cylindrical portion 6a) is slightly extended from the front end of the lens barrel 4a, and the second frame 7a is further retracted by the amount of rearward projection, resulting in a wide state.

Next, to explain the storage operation from the above-mentioned wide state to the storage state shown in FIGS. 6 and 11, the lens barrel drive gear 17 and the first group drive gear 16 are rotated counterclockwise in the same manner as described above. do. Therefore, the lens barrel frame 4 and the first group frame 6 each continue to move backward as described above. However, the first
As shown in Figure 1, in the storage area where the storage operation is performed, the protruding member 49 collides with the stopper portion 1e of the fixed frame 1, so the second frame 7a cannot move back any further and maintains its position. However, since the first group frame 6 (first group board 6b) and lens barrel frame 4 move further back, the cam surface 9a is relatively
It will move away from the cam pin 7b rearward against the group springs 10a, 10b. Then, as shown in Figure 6, ll
t The front end portions of the trunk frame 4 and the first group frame 6 are aligned approximately in a straight line with the front plate 1a, and the rearward protrusion amount of the second part frame 7a is the minimum (zero), that is, the The storage state is reached in which the rear end of the second group frame 7a is aligned approximately in a straight line with the first group board 6b.

Next, the operation of changing the magnification in the long focal point direction from the above-mentioned storage state to the telephoto state shown in FIGS. 1, 8, and 9 will be briefly described.

By switching the polarity of supply to the motor 11, causing the motor 11 to rotate in the opposite direction, and rotating the driving gear lla counterclockwise,
Lens barrel drive gear 17 and first group drive gear 16 all rotate clockwise. Therefore, the lens barrel frame 4 is extended forward, and the first group frame 6 is further extended forward relative to the extended lens barrel frame 4. Moreover, if we pay attention only to the first group frame 6 and the second part frame 7a, as shown in FIGS. 11 and 10, even if the first group frame 6 (first group board 6b) is extended, the second part frame 6 Frame 7a
is pulled to the first group substrate 6b by the second group spring 10a, so only the first group frame 6 moves forward while maintaining its position, and the first group frame 6 moves forward to the position shown in FIG. since,
This will be the first time that the first part frame cam 9 is regulated. In other words, the second part frame 7a is not restricted by the cam surface 9a between the storage state and the wide state, that is, in the storage area.

Further, the lens barrel frame 4 and the first group frame 6 move forward, the crown gear 9b rotates clockwise, and this rotation presses the cam pin 7b slidingly in contact with the cam surface 9a obliquely forward, and the slider 7c and the The two-part frame guide 8 converts the motion into a straight motion, and the second group 7a is extended forward. As shown in FIG. 8 and FIG. 1, the lens barrel frame 4 is connected to the fixed frame 1,
The first group frame 6 is extended approximately the maximum amount relative to the lens barrel frame 4, the second part frame 7a is also extended approximately the maximum amount in front of the first group board 6b, and the rear end of the second part frame 7a is extended to the first part. A telephoto state is reached in which the image is aligned with the frame 6b.

As described above, according to this embodiment, the lens barrel frame 4 is movably supported along the three guide shafts 24 to 26 substantially parallel to the optical axis 3 fixed to the fixed frame 1. A first group frame 6 supporting a lens group 5 is movably supported by a plurality of guide shafts (not shown) fixed to the lens barrel frame 4 in a state substantially parallel to the optical axis 3, and further includes a second frame cam. 9, a second part frame 7a supporting the second lens group 7 is supported so as to be movable back and forth, and the lens barrel frame 4 is moved by a transmission mechanism driven via a drive shaft 13a and a moving gear 13b. The three lens barrel drive screws 18 to 20 are used to move the first group frame 6 forward and backward, and the three first group drive screws 21 to 23 are used to move the first group frame 6 forward and backward. Since the second group drive section is configured to move the second group frame forward and backward using the second group frame as a drive source, the following advantages can be obtained.

For example, when the second part frame 7a is directly driven from the fixed frame 1 via a gear reduction mechanism etc., more specifically, when the crown gear 9b is driven from the drive shaft 13a via the above-mentioned reduction mechanism etc. (This will be referred to as "direct drive" hereinafter), since the crown gear 9b is disposed inside the lens barrel 4a, a long horizontal hole along the optical axis direction must be bored in the lens barrel 4a. Although the configuration would be complicated, according to this embodiment, there is no need for such a configuration, and a large speed reduction ratio can be obtained even though the speed reduction mechanism and the like are simple. Furthermore, if the amount of extension from the wide-angle state to the telephoto state is LO, then the amount of extension of the lens barrel frame 4 is Ll.
and the amount of extension of the first group frame 6 is L2, rut, L1+L
It is clear that 2=LO, LO>Ll, and LO>L2, and the amount of movement (feedout amount L2) that is shorter than the feedout amount LO of the above-mentioned direct drive is sufficient. Therefore, * of this first group frame 6
Since the differential relative to the mq frame 4 can be detected by the lens barrel rack 32, cam drive gear 33, etc. and transmitted to the second frame cam 9, it is not necessary to provide the second group drive section with a large reduction ratio. It has the advantage that it can be made smaller.

Furthermore, even if the amount of movement of the lens barrel frame 4 is changed, there is an advantage that this can be handled simply by changing the gear ratio of the transmission gear 14 (two-stage gear).

In addition, since the lens barrel frame 4 and the first group frame 6 are configured to be driven by the three lens barrel drive screws 18 to 20 and the first group drive screws 21 to 23, the movement of the lens barrel frame 4 and the first group frame 6 causes the lens group to move. There is an advantage that the disadvantage of the conventional example that the postures of the lens group 5 and the second lens group 7 become unstable can be eliminated.

In addition, as mentioned above, the second group drive unit can be made smaller, and since the lens barrel frame 4 and the first group frame 6 move forward and backward with respect to the fixed frame 1, the focal length can be changed over a wide range. Even though this is possible, it has the advantage that in the stored state, the length in the three directions of the optical axis can be shortened compared to the conventional one, making it extremely small and highly compact.

Further, since a conventional cam ring is not used, the manufacturing cost of the cam ring can be saved, and there is an advantage that the cam ring can be manufactured at low cost.

Further, since the amount of movement of the first group frame 6 and the lens barrel frame 4 can be easily set by the gear ratio of the transmission gear 14 consisting of two-stage gears, there is an advantage that there is a large degree of freedom in design.

In addition, the lens barrel drive screws 18 to 20 and the first group drive screw 2
1 to 23, the amount of movement of the lens barrel frame 4 and the first group frame 6 can be set by changing the respective leads, which increases flexibility in design, for example, when installing a light leakage prevention mechanism, etc. It has the advantage of having a large degree of freedom.

In addition, the mirror I51 drive screws 18 to 2o are precisely regulated in position in the axial direction at each end 18a, 19a and 18b, 19b, but there is a moderate play (room) in the circumferential direction. Therefore, the lens barrel drive screws 18 to 20, the first group drive screws 21 to 23, and the lens barrel drive gear 17 and the first group drive gear 16 that are screwed thereto.
Furthermore, even if there are manufacturing errors in the entire transmission mechanism, there is no need to apply unreasonable force to them, resulting in smooth operation and no worries about overloading the motor 11, etc. be.

Further, one of the lens barrel drive gear 17 and the first group drive gear 16
The rotation axis is the barrel drive screws 18 to 20 and the first group drive screw 2.
Since the movement is one pitch from 1 to 23, there is an advantage that the feeding accuracy is high.

Further, since members such as the motor 11 and the reduction gear train 12 that require a large installation space are fixed to the fixed frame 1, there is an advantage that a large space required to move them is not required.

Further, the lens barrel frame 4, the first part frame 6. The second group frame 7a.

Since the movement is performed simultaneously rather than sequentially, there is an advantage that the operation time can be shortened.

Further, since the lens barrel rack 32 has a fine adjustment mechanism, there is an advantage that adjustment with the second part frame 7a is facilitated.

In addition, the second group springs 10a, 10b, the lens barrel spring 27
．． 28 and the first group springs 29 to 31 can eliminate adverse effects such as backlash, which has the advantage of further improving accuracy.

It should be noted that the present invention is not limited to the above-described embodiments, and can be modified in various ways without departing from the spirit thereof.

For example, as illustrated in this embodiment, the barrel drive screw 18
20 to be right-handed threads and the first group drive screws 21 to 23 to be left-handed threads may be changed in accordance with the specifications of the transmission mechanism section.

Further, in the above embodiment, the lens barrel spring 27.2
8, a compression spring is used, and the second group springs 10a, f
Although tension springs are used as ob and the first group springs 29 to 31, springs having opposite functions may be used if the springs are selected.

Further, the cross section of the drive shaft 13a is not limited to an oval shape, but may be a spline or similar shape as long as compatibility with the drive gear 13 and the moving gear 13b is considered.

Moreover, the crown gear 9b and the connection gear 33b may each be configured with a bevel gear.

Further, the movement amount detection section includes the lens barrel rack 32 and the pinion 33.
The structure is not limited to the configuration with a and a, but in short, any device that detects the relative displacement between the lens barrel frame 4 and the first group frame 6 and transmits this to the second part frame 7a. good.

(e) Effects As is clear from the above detailed description, according to the present invention, the structure is simple and machining is easy, so costs can be reduced, and the variable focal length Despite being able to widen the range, it can be stored very compactly when not in use, especially by positioning the first and second lens groups in a positional relationship that corresponds to the intended focal length. It is possible to provide a driving device for a variable focus lens whose mechanism part can be made compact and simple.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view showing the overall configuration of an embodiment of a variable focus lens driving device according to the present invention, and FIG. FIG. 3 is a schematic diagram of the transmission mechanism section viewed from the rear of the optical axis, and shows a part of the transmission mechanism section, with the first group drive gear 16b in FIG. 1 as a representative. FIG. 4 is an enlarged vertical side view showing the configuration, FIG. 4 is an enlarged perspective view showing the configuration of both ends of the lens barrel drive screw 19 in FIG. 1 as a representative, and FIG. FIGS. 6 to 8 are longitudinal cross-sectional views showing in detail the configuration of the end portion of the first group drive screw 22 supported by the first group board 6b as a representative, and FIGS. This diagram schematically shows three states associated with the operation of the example. Of these, Fig. 6 shows the stored state when not in use, and Figs. 7 and 8 show the short focal length side and the short focal length side, respectively. The longitudinal sectional views shown in FIGS. 9 to 11 showing the wide-angle state and telephoto state switched to the long focus side are used to explain the operation of the first group frame and the second group frame of the same embodiment. FIG. 9 is a schematic side view with a portion cut away, of which FIG. 9 corresponds to the telephoto state, FIG. 10 corresponds to the wide state, and FIG. 11 corresponds to the stored state. FIGS. 12 and 13 show the operation of the second group drive section consisting of the lens barrel rack, cam drive gear train, and first group cam, which are the main parts of the present invention, and the fine adjustment mechanism for finely adjusting the lens barrel rack. In order to explain the sections, the 12th
The figure shows the magnification change operation from wide-angle to telephoto.
The figures each show the magnification changing operation from the telephoto state to the wide state. 1...Fixed frame, 1a...
front board. 1b... Rear plate, IC...
Front window, 1d...Rear window, 1e...
...Stopper part, 2...Third lens,
3...Optical axis, 4... Lens barrel frame,
4a... Lens barrel, 4d... Lens barrel board, 5... 1st lens group, 6... 1st group frame, 6b...・First group board, 7...
...Second lens group, 7a...Second group frame, 7b...Cam pin, 8...Second frame guide, 9... Second frame cam, 9a...cam surface, 9b...crown gear, 10a, 10b...second group spring, 11...
...Motor, 12...Reduction gear train,
13... Drive gear, 13a...
drive shaft. 13b...Movement gear, 14 (14a, 14b, 14c) - Transmission gear, 15... Annular gear, 16 (16a, 16b, 16c) - First group drive gear , 17 (17a, 17b, 17c) - Lens barrel drive gear. 18-20... Lens barrel drive screw, 21-23...
...First group drive screw, 24-26...Guide shaft, 27.28... Lens barrel spring, 29-31.
...First group spring, 32 ... Lens barrel rack, 33 ... Cam drive gear train, 33a ... Pinion, 33b ... Connection Gear, 49...Protruding member. Patent applicant Rico Co., Ltd. −

Claims (2)

[Claims] (1) Determine the focal length of a variable focus lens consisting of a variable focus optical system in which at least a first lens group and a second lens group are arranged on the same optical axis, and the first lens group is used as a focusing lens. In a variable focus lens driving device that performs a magnification changing operation in which the first and second lens groups are each driven by a predetermined amount in order to change the magnification, the fixed frame is fixed to a fixed part of an optical device such as a camera, and the fixed frame The lens barrel frame is supported movably along the optical axis inside the lens barrel frame, and the first lens group is supported so as to be capable of focusing. a first member supported so as to be movable in parallel to the axis;
a group frame; a movement amount detection unit that detects the amount of movement of the first group frame in the optical axis direction with respect to the lens barrel frame; a motion converter that converts the amount of movement into a rotation amount; a variable power cam that is rotatably supported about the optical axis and rotationally driven by the motion converter in accordance with the amount of movement; and a variable power cam that is fixedly supported by the second lens group; a second group frame that is driven and movable along the optical axis under the control of a transmission mechanism; and a member that is driven by the transmission mechanism to drive the lens barrel frame and the first group frame by a predetermined amount, and is perpendicular to the optical axis of the lens barrel frame and the first group frame. is provided with at least three driving screws that move each of the lenses in parallel in the optical axis direction while holding the lens barrel at a substantially right angle, and the lens barrel frame and the first group frame are differentially moved to change the magnification of the second group frame. 1. A driving device for a variable focus lens, characterized in that the device is configured to drive the first lens group and the second lens group in a positional relationship corresponding to a predetermined focal length. (2) The movement amount detection unit is rotatably supported by the lens barrel rack attached to the lens barrel frame so that its mounting position in the optical axis direction can be finely adjusted, and is rotatably supported by the first group frame and meshes with the lens barrel rack. 2. The variable focus lens driving device according to claim 1, further comprising a pinion.