JP2843316B2 - Lens barrel - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel, and more particularly to a motor such as an electromagnetic motor and driven members such as a diaphragm device and a lens frame driven by the motor. It relates to a lens barrel. 2. Description of the Related Art A conventional lens barrel will be described with reference to FIGS. FIG. 2 is a sectional view of a conventional lens barrel.
A fixed frame 2 is fixed to a lens mount 1 detachably mounted on a camera mount (not shown). An outer frame 3 is fixed to the outer periphery of the fixed frame 2. A zoom ring 4 is rotatably fitted around the optical axis at a rear portion of the outer peripheral surface of the outer frame 3. The zoom ring 4 is restricted from moving in the optical axis direction by a step portion 5 of the outer frame 3 and a press ring 6 fixed to the outer periphery of the lens mount 1. A cam frame 7 is fitted on the outer peripheral surface of the fixed frame 2 so as to be rotatable around the optical axis. The movement of the cam frame 7 in the optical axis direction is restricted by a C-ring 8 fitted into the front end of the outer peripheral surface of the fixed frame 2 and a flange 9 provided at the rear end of the fixed frame 2. The cam frame 7 is connected to the outer ring 3 via a relief groove 10 provided around the optical axis by a zoom pin 11 so as to rotate integrally with the zoom ring 4 around the optical axis. An outer helicoid frame 12 having a large diameter at the front is fitted on the inner peripheral surface of the fixed frame 2 at a small diameter portion behind the outer helicoid frame 12 so as to be movable in the optical axis direction. An outer helicoid screw 13 is provided on the inner peripheral surface of the large diameter portion at the front of the outer helicoid frame 12. Further, a roller 14 is planted on the outer peripheral surface of the rear small diameter portion of the outer helicoid frame 12. The roller 14 is a long groove 1 provided in the fixed frame 2 and extending in the optical axis direction.
5, and is fitted into a cam groove 16 provided in the cam frame 7. [0005] A first lens group frame 17 for holding the first lens group L1 is fitted into the inner peripheral surface of the front large diameter portion of the outer frame 3.
The first lens group frame 17 has an inner helicoid screw 18 that meshes with the outer helicoid screw 13 of the outer helicoid frame 12. Move back and forth in the direction. A second lens group frame 19 for holding the second lens group L2 is provided on the inner peripheral surface of the rear small diameter portion of the outer helicoid frame 12.
And the third lens group frame 20 that holds the third lens group L3 is fitted. A roller 21 is implanted on the outer peripheral surface of the second lens group frame 19. The roller 21 is provided with an escape groove 22 provided on the outer helicoid frame 12 and a long groove provided on the fixed frame 2 and extending in the optical axis direction. Through 23, it is fitted into a cam groove 24 provided in the cam frame 7. Further, similarly, a third lens group frame 20 provided behind the second lens group frame 19 has a roller 25 on its outer peripheral surface.
Is planted. This roller 25 is the same as the roller 21 described above.
Similarly, the escape groove 26 provided in the outer helicoid frame 12 is provided.
And a long groove 27 extending in the optical axis direction provided in the fixed frame 2, and is fitted into a cam groove 28 provided in the cam frame 7. An aperture device 29 is fixed to the front end face of the third lens group frame 20. As shown in FIG. 3, the diaphragm device 29 includes a blade case 30, a diaphragm blade 31, a wheel wheel 32, and a C-ring 33. Although seven aperture blades 31 are actually provided, only one is shown in FIG. 3 to avoid complication. The blade case 30 has a substantially cylindrical shape, and forms an inner protruding surface 34 that forms a maximum aperture at its rear end surface. Further, a wall portion 35 is formed on the front surface of the blade case 30 so as to protrude forward and cut off a part of the circumference. Further, the wall portion 35 has a circumferential groove 36 extending around the optical axis on its inner peripheral surface. The inner protruding surface 34 has pins 37 protruding forward at equal intervals around the optical axis and parallel to the optical axis. The pin 37 is fitted into a through hole 38 formed in the diaphragm blade 31 and rotatably supports the diaphragm blade 31. The aperture blade 31 is provided with an aperture driving pin 3 that projects forward in parallel with the optical axis.
9 The iris drive pin 39 fits into an iris drive groove 40 formed in the wheel 32. A radial gear 42 is provided on a projection 41 projecting radially on the circumference of the arrow wheel 32. The diameter of the gear 42 is larger than the outer diameter of the blade case 30, and the circumferential width of the protrusion 41 is smaller than the circumferential width of the cutout of the wall 35. The pin 37 of the blade case 30 and the aperture blade 3
The aperture blade 31 can be connected to the blade case 30 by the one through hole 38.
And the aperture driving pin 3 of the aperture blade 31
9 fits into the aperture drive groove 40 of the wheel 32, and the wheel 3
2 is attached. Finally, the C-ring 33 is fitted into the circumferential groove 36 of the blade case 30 so that the aperture blade 31 and the wheel 32
Are integrally held by the blade case 30 in the optical axis direction. At this time, the gear 42 protrudes outward from the blade case 30 through the cutout of the wall 35. The gear 42 meshes with the output gear 47 of the motor 44. The pin 37 and the aperture driving groove 40 in FIG.
Shows only one set to avoid complication as in the case of the diaphragm blade 31. As shown in FIG. 2, a motor 44 is mounted on the protrusion 43 on the inner peripheral surface of the fixed frame 2. An output shaft 45 of the motor 44 is supported by a through-hole 46 provided in the third lens group frame 20, and an output gear 47
Is fixed. The length of this output gear 47 in the optical axis direction is
The amount of movement of the third lens group holding frame 20 with respect to the fixed frame 2 during a zooming operation described later is longer than that of the third lens group holding frame 20, and the output gear 47 always meshes with the gear 42 of the diaphragm device 29. A fixed terminal 48 is fixed to the inner peripheral surface of the lens mount 1 to be in contact with an electric contact on the camera (not shown). The fixed terminal 48 and the motor 44 are electrically connected by a flexible printed circuit board (hereinafter abbreviated as FPC) 50 that passes through a through hole 49 provided in the fixed frame 2. Further, a control unit 51 is provided on the FPC 50 as shown in FIG. Next, the operation of the lens barrel configured as described above will be described. When the zoom ring 4 is rotated around the optical axis, the rotation is transmitted to the cam frame 7 by the zoom pin 11. When the cam frame 7 is rotated, the cam frame 7 is rotated.
The rollers 14, 21, 25 are respectively moved back and forth in the optical axis direction by the cam grooves 16, 24, 28 provided in the fixed frame 2 and the long grooves 23, 27 and the escape grooves 22, 26 provided in the fixed frame 2 and the outer helicoid frame 12. Accordingly, the outer helicoid frame 12, the first lens group frame 17, the second lens group frame 19, and the third lens group frame 20 are moved back and forth in the optical axis direction. FIG. 4 shows each lens group L of the lens barrel.
The movement diagram of 1, L2, L3, L4 is shown. In the figure, the symbol W indicates the wide-angle side, and the symbol T indicates the telephoto side. By rotating the zoom ring 4, each lens group L1, L2, L3, L
4 move like A, B, C, and D in FIG. W
Lens units L1, L2, L when moving from side to T side
The movement amounts of 3 and L4 are z, y, x, and 0, respectively. That is, the stop device 29 fixed to the third lens group frame 20
The amount of movement with respect to the fixed frame 2 due to the zooming operation is X, and the length of the output gear in the optical axis direction is X in this lens barrel.
Designed longer. The motor 44 does not move at all with respect to the fixed terminal 48 even when the zooming operation is performed, so that the FPC 50 does not need a folded portion, and the FPC 50 is always in a stable state. Next, the operation of the diaphragm device 29 will be described. The control unit 51 drives the motor 44 in accordance with the aperture value determined by the camera body (not shown). The motor 44 is rotated to obtain a predetermined aperture value, and the wheel 32 is rotated by the gear 42. By rotating the wheel 32, the aperture driving groove 40 drives the aperture driving pin 39 fitted in the groove, and rotates the aperture blade 31 about the pin 37. As a result, the aperture blade 31 forms a predetermined aperture diameter. When the aperture diameter is set to the open state, the motor 44 may be rotated in a direction opposite to the above. Next, another example of a conventional lens barrel will be described with reference to FIGS. In FIGS. 5 and 6, the same members as those in the lens barrel in FIGS. 2 to 4 described above are denoted by the same reference numerals, and detailed description is omitted. FIG. 5 is a partial sectional view showing another example of a conventional lens barrel. The motor 44 is fixed to the through hole 58 of the fixed frame 2 with the output shaft 52 facing rearward. An aperture ring 53 is rotatably fitted on the inner peripheral surface of the lens mount 1, and movement in the optical axis direction is restricted by a C ring 54. A drive gear 55 is provided on the inner peripheral surface of the aperture ring 53 as shown in FIG. The drive gear 55 meshes with an output gear 56 fixed to the output shaft 52 of the motor 44. A drive rod 57 extending in the optical axis direction is fixed to the aperture ring 53. The drive rod 57 passes through through holes 58 and 59 provided in the fixed frame 2 and the third lens group frame 20, and the tip thereof is provided in the projection 41 of the wheel 32 in the aperture device 29 as shown in FIG. The notch 60 is engaged. This conventional lens barrel has a zoom ring 4
Is rotated to perform a zooming operation. By rotating the zoom ring 4, the cam frame 7 is rotated. By this rotation, the third lens group frame 2 in which the roller 25 is fitted into the cam groove 28 via the long groove 27 of the fixed frame 2
0 is moved back and forth. The aperture device 29 fixed to the third lens group frame 20 is also moved back and forth. However, while the relative position of the arrow wheel of the aperture device 29 and the driving rod 57 of the aperture ring 53 is changed in the optical axis direction, light is always They are integrally engaged around the axis. Therefore, the rotation of the aperture ring 53 is always transmitted to the wheel 32. The control unit 51 drives the motor 44 in accordance with the aperture value determined by the camera body (not shown). The motor 44 rotates to obtain a predetermined aperture value, and the aperture ring 53 is rotated. This rotation is transmitted to the wheel 32 via the drive rod 57. By this rotation, the aperture blade 31 forms a predetermined aperture diameter. To set the aperture to the open state, the motor 44 may be rotated in the direction opposite to the direction in which the aperture is stopped down, as in the first embodiment. In the above-described conventional lens barrel, the motor 44, the output shaft 45, and the output gear 47 occupy much space in the optical axis direction in the lens barrel. Have the disadvantage that In another lens barrel in the prior art, when a moving amount of a lens group frame holding a diaphragm mechanism, a shutter mechanism and the like during a zooming operation is large, a motor for driving the diaphragm mechanism is fixed. If it is provided on the side, a space in the optical axis direction is required to transmit the driving force to the aperture mechanism, and there is a disadvantage that the entire lens barrel becomes large. An object of the present invention is to provide a lens barrel in which the disadvantages of the lens barrel in the prior art described above are eliminated. In order to solve the above-mentioned problems, the present invention provides a first lens barrel having a driven member and moving in the optical axis direction together with the driven member; A second lens frame having an electric drive source for driving the driven member and moving in the optical axis direction together with the electric drive source, and a relative position between the first lens frame and the second lens frame; Driving lens connecting means for constantly transmitting the driving force of the electric driving source to the driven member so that the electric driving source can drive the driven member even when the position changes. It is provided in. Embodiments of the present invention will be described below in detail with reference to the drawings. Note that, in the present embodiment, the same reference numerals are given to the lens barrel and the same members in the above-described conventional technology, and detailed description is omitted. FIG. 1 is a sectional view of a lens barrel showing one embodiment of the present invention. A motor 44 is fixed to the inner peripheral surface of the second lens group frame 19 with the output shaft 45 facing rearward. The motor 44 and a fixed terminal 48 fixed to the lens mount 1
Are electrically connected by FPCs 50 passing through through holes 65 and 66 provided in the fixed frame 2 and the third lens group frame 20, respectively. An output shaft 45 of the motor 44 has an output gear 47
Is fixed. The output gear 47 meshes with the gear 42 provided on the wheel 32 of the expansion device 29. Here, referring to the movement amount of each lens group with reference to FIG.
The movement amount of the lens unit L3 and the third lens unit frame 20 due to the zooming operation is x as shown in FIG. On the other hand, the moving amount of the second lens group frame 19 is y, which is a very small displacement with respect to the fixed frame 2. With this amount of movement, there is no need to provide the FPC 50 with a fold.
Only the slack of the FPC 50 can sufficiently cover the moving range of the second lens group frame 19. When a zooming operation is performed by the zoom ring 4, the first to third lens unit frames 17, 19, and 20 move back and forth in the optical axis direction. However, as described above, the amount of movement of the second lens group frame 19 is extremely small. Even if the third lens group frame 20 moves, the output gear 47 always meshes with the gear 42 in this movement range. As the motor 44 is driven in the same manner as the above-described conventional lens barrel, the wheel 32 rotates and the aperture blade 31 is narrowed down to a predetermined aperture. With the configuration as described in the embodiment described above, the output gear of the motor can be shortened, and the size of the lens barrel can be reduced. As described in detail above, according to the present invention, a first lens barrel having a driven member, which moves in the optical axis direction together with the driven member, and the driven member, A second lens frame that has an electric drive source for driving, and moves in the optical axis direction together with the electric drive source, and a relative position between the first lens frame and the second lens frame changes. Also, by providing the lens barrel with driving force coupling means for constantly transmitting the driving force of the electric driving source to the driven member so that the electric driving source can drive the driven member, Along with moving in the optical axis direction with respect to the fixed frame, the electrically driven source and the driven member that move relatively in the optical axis direction can always be connected, and the space in the lens barrel can be increased. Without occupation, the size of the lens barrel can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a lens barrel according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of a lens barrel according to the related art. FIG. 3 is a perspective view showing a connection state of a diaphragm device and a motor in the lens barrel of FIG. 2; FIG. 4 is a diagram showing the amount of movement of each lens L1, L2, L3, L4 by a zooming operation in the lens barrel of FIG. 2; FIG. 5 is a partial cross-sectional view showing another example of a lens barrel in the related art. FIG. 6 is a perspective view showing a connection state between the aperture device and the motor in FIG. 5; [Description of Signs] 2 Fixed frame 19 Second lens group frame (second lens frame) 20 Third lens group frame (first lens frame) 29 Aperture device (driven member) 44 Motor (electrically driven source) 47 Output gear (drive force connecting means)

Claims (1)

(57) [Claims] A first lens frame having a driven member and moving in the optical axis direction together with the driven member; and an electric drive source for driving the driven member, wherein the first lens frame is moved in the optical axis direction together with the electric drive source. A moving second lens frame, such that the electric drive source can drive the driven member even if a relative position between the first lens frame and the second lens frame changes. And a driving force coupling means for constantly transmitting the driving force of the electric driving source to the driven member.