JP4033879B2 - Zoom lens device - Google Patents

Description

  The present invention relates to a zoom lens apparatus that performs focusing along an optical axis according to different driving forces.

  FIG. 7 is an exploded perspective view of the conventional zoom lens device 10, and FIG. 8 is an assembly vertical sectional view of the zoom lens device 10. This zoom lens device 10 is generally composed of a fixed cylinder 11, a lens frame 14, a driving means 13, and a cam cylinder 12.

  The cam cylinder 12 is provided outside the fixed cylinder 11 and is rotatable around the optical axis X. A plurality of, for example, three circumferential grooves 123 including the optical axis direction component (X3) and the circumferential direction component, and circumferential grooves 123 along the circumferential direction component are provided in the circumferential wall 121 of the cam cylinder 12 at substantially equal intervals in the circumference. Has been. A plurality of cam pins 143, 143, 143, 124, 124, 124 provided on the outer peripheral surface of the cam cylinder 12 are provided on the outer peripheral wall of the lens frame 14 through the corresponding spiral grooves 122 and the peripheral grooves 123, respectively. By engaging with the concave hole 144 and the concave hole 113 provided in the outer peripheral wall of the fixed cylinder 11, it moves and circulates around the optical axis direction and the optical axis X (circumferential direction). An inner tooth portion 125 for rotational driving is formed on the inner peripheral surface of one end portion of the peripheral wall 121 of the cam cylinder 12.

  The drive means 13 includes a motor 131, a reduction gear 132, and a drive gear 133. The drive gear 133 is connected to the output shaft of the motor 131 via the reduction gear 132, and is cut out and provided through the peripheral wall of the fixed cylinder 11. The inner teeth 125 are engaged with each other through the slot 112.

  A lens 142 (actually an objective lens set, but described as one lens 142 for the sake of convenience) is housed in the lens frame 14, and the cam pins 143 of the cam cylinder 12 are inserted into a plurality of recesses 144 provided on the outer peripheral surface of the lens frame 14. Is inserted and can rotate with the movement of the cam cylinder 12.

  In this configuration, focusing in the X direction is performed by rotating the cam cylinder 12 in the Y direction by the driving force from the driving means 13 and rotating the lens 142 to a predetermined angle.

  According to the above configuration, focusing can be performed with a simple structure. However, in order to engage the gears, the sliding between the spiral groove 122 and the cam pin 143 and the sliding between the circumferential groove 123 and the cam pin 124 is structurally free backlash. Since it is unavoidable, it is already known that backlash simultaneously affects the accuracy of correlation movement. The noise of the zoom lens apparatus 10 due to backlash includes the sliding noise between components such as the sound generated when the cam pins 143 and 124 slide in the spiral groove 122 and the circumferential groove 123 which are cam grooves, and the driving gears. There is something like friction noise. The influence (noise, etc.) due to the backlash can be reduced by appropriately adjusting the driving force of the driving means, for example, between the deceleration rate of the driving means 13 and the groove length of the spiral groove 122 and the circumferential component. The driving force can be adjusted by the magnitude of the rising angle γ (the remainder of the helical angle θ) (FIG. 7). However, the rising angle γ and the deceleration rate of the spiral groove 122 in the zoom lens device 10 are generally determined by a high-speed moving load and the best focusing accuracy. When only one set of driving means 13 is used, In order to increase the speed, the driving force from the motor 131 is large, but the focusing accuracy is low, and the sliding noise caused by the gears 132 and 133 is also large. On the other hand, when the driving means 13 is driven at a low speed, the focusing accuracy is good. However, if the focusing speed is not reduced, the rising angle γ of the spiral groove 122 must be increased, and the noise there is increased. It might be. According to the configuration of the zoom lens device 10, it is difficult to achieve a balance between focusing accuracy and backlash prevention.

  The present invention has been made to solve the above-mentioned problems, and by providing different driving means provided in accordance with helical grooves having different helical angles, the focusing accuracy is improved and the focusing speed is reduced. An object of the present invention is to provide a zoom lens device that can be dispensed with.

  In order to achieve the above object, a zoom lens device of the present invention includes a cylindrical main body having a peripheral wall having an optical axis as a central axis, and a cylindrical body having an optical axis as a central axis, and one end portion of the cylindrical body. A first annular wall rotatably provided outside the peripheral wall, and a plurality of first spiral grooves having a circumferential component and an optical axis component are provided in the first annular wall. The first cam member is connected to the first cam member so that the first cam member can be driven to rotate, and a cylindrical shape having an optical axis as a central axis and loosely fitted in the first cam member in a nested manner. One end of which has a second annular wall rotatably provided on the outer peripheral wall of the main body, the second annular wall having a circumferential component and an optical axis component, and the first annular wall. A second cam member having a plurality of second helical grooves penetrating through the second helical groove having a helical angle different from that of the helical groove; Second driving means to which the cam member is rotatably connected, and an annular portion having the optical axis as a central axis are provided inside the first annular wall of the first cam member, A cylindrical portion formed of a slightly thicker inner wall with a gap that can loosely hold the first and second cam members in a nested manner holds the ring portion in a freely movable manner near the opening end, A plurality of first cam pins that are movably inserted into a first spiral groove of a first cam member loosely fitted in the gap are planted in the ring portion, and the cylindrical portion has a gap in the gap. A plurality of second cam pins that are inserted into the second spiral grooves of the loosely-fitted second cam member are implanted, and the lens frame means that holds the lens inside the ring portion or the cylindrical portion is provided. It is characterized by having a configuration.

  According to the present invention, since the plurality of cam members having spiral grooves having different spiral angles can be driven at different speeds by different driving means according to the above configuration, focusing can be performed accurately without reducing the speed. This can be performed, and noise due to backlash can be reduced as much as possible.

  Hereinafter, the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the examples.

  FIG. 1 is an exploded perspective view showing a schematic configuration of a zoom lens device 1 according to a preferred embodiment of the present invention, and FIG. 2 is an assembly vertical sectional view of the zoom lens device 1. In the following description, the broken line X is the central axis that is also the optical axis of this apparatus, and the rising angles γ1 and γ2 are the complementary angles of the helical angles θ1 and θ2, respectively (the same applies to the drawings).

  As shown in FIGS. 1 and 2, the zoom lens device 1 according to the embodiment of the present invention drives the cylindrical main body 2, the first and second cam members 3, 5, and the second cam members 3, 5 respectively. The first and second driving means 4 and 6 and the lens frame means 7 that can move relative to the two cam members 3 and 5 are included.

  The cylindrical main body 2 has a peripheral wall 21 whose central axis X is on the optical axis, and is fixedly supported by a housing such as an imaging device (not shown). In the peripheral wall 21 of the main body 2, a first through hole 23 is formed by cutting from the leading edge 211 of the peripheral wall 21, and the second through hole 22 is opened away from the first through hole 23. The peripheral wall 21 of the main body 2 is also provided with a plurality of concave holes 25 and a plurality of cam pins 24, 24,. In this embodiment, a plurality of cam pins 24 and concave holes 25 are provided, for example, at three locations in the circumferential direction.

  The first cam member 3 has a first annular wall 31 that is cylindrical and has one end portion 311 in the direction of the central axis X that is rotatably provided on the outer side of the peripheral wall 21 of the main body 2. The annular wall 31 includes a plurality of, for example, three first circumferential grooves 33, 33, 33 for restricting rotation of the first cam member 3 along the circumferential component penetrating in the circumferential direction, and a circumferential component. A plurality of, for example, three first spiral grooves 32, 32, 32 having (X1) and an optical axis direction component are formed. At one end of the inner peripheral surface 312 of the first annular wall 31, a first inner tooth portion 34 is provided in a ring.

  The first driving means 4 is provided in the main body 2, and is connected to the motor 41, the reduction gear 42 that is connected to the motor 41 and adjusts the driving force from the motor 41, and the reduction gear 42. The first cam is constituted by a drive gear 43 that meshes with the first internal tooth portion 34 via the through hole 23 and transmits the driving force output from the motor 41 to the first cam member 3. The first cam member 3 can be rotated around the central axis X while limiting the degree of rotation of the member 3 in the circumferential direction.

  The second cam member 5 has a cylindrical shape, and has a second annular wall 51 in which a distal end portion 511 in the central axis X direction is rotatably provided outside the peripheral wall 21 of the main body 2. A circumferential groove 53 for restricting the rotation of the second cam member 5 along the circumferential direction on the wall 51, and a rising angle of the first helical groove 32 having a circumferential component and an optical axis component (X2) A plurality of, for example, three second spiral grooves 52, 52, 52 having a rising angle γ2 different from γ1 are formed. In this embodiment, the helical angle θ1 of the first helical groove 32 is larger than the helical angle θ2 of the second helical groove 5, and the rising angle γ1 is smaller than the rising angle γ2. On the inner peripheral surface 512 of the second cam member 5, a second inner tooth portion 54 is provided in a ring.

  The second driving means 6 has substantially the same configuration as the first driving means 4, but is set to a deceleration rate different from that of the first driving means 4, and the driving force from the motor 61 is , The reduction gear 62 connected to the motor 61 is transmitted to the second internal tooth portion 54 from the connected drive gear 63 through the second through hole 22, and the second cam member 5 is The second cam member 5 is rotated while limiting the degree of rotation in the circumferential direction.

  The lens frame means 7 includes an annular lens frame 71 (ring portion) that holds the lens 73 and has an optical axis as a central axis, and a cylindrical frame 72 (cylindrical portion) that integrally holds the lens frame 71. In this embodiment, the lens frame 71 is a substantially annular member having a central opening, and a lens 73 is attached to the central opening 711. The lens frame 71 is connected to the main body 2 in the front-rear direction and close to the opening end of the first cam member 3. The first annular wall 31 is loosely fitted inside. The outer peripheral surface 712 of the lens frame 71 is provided with concave holes 716, 716, 716, cam pins 713, 713, 713 are implanted, and the end surface 717 in contact with the main body 2 has an arc shape penetrating along the optical axis direction. Three slots 714, 714, 714 and cam pins 715, 715, 715 are provided in the circumferential direction. The cylindrical frame 72 includes an outer peripheral wall 722 and a slightly thicker inner peripheral wall 721 with a gap 723 in which the first and second cam members 3 and 5 can be loosely fitted and held. In this embodiment, the inner peripheral wall 721 of the cylindrical frame 72 is made shorter than the outer peripheral wall 722 to form a stepped portion. Through holes 725, 725, and 725 are provided in the circumferential direction at the opening end of the outer peripheral wall 722 (portions protruding from the inner peripheral wall 721), and cam pins 724, 724, and 724 are attached. The lens 73 is mounted in the lens frame 71, but may be mounted directly in the cylindrical frame 72 in some cases.

  In the assembled state of the zoom lens device 1, as shown in FIG. 2, each of the cam pins 713 (first cam pins) slides in the corresponding first spiral groove 32 of the first cam member 3. It is movably inserted and fixed in a corresponding concave hole 716 of the lens frame 71. Each of the cam pins 724 (second cam pins) is slidably inserted into the corresponding through hole 725 of the outer peripheral wall 722 of the cylindrical frame 72 and the corresponding second spiral groove 52 of the second cam member 5. . Accordingly, the lens frame means 7 can be advanced and retracted at different speeds in the central axis direction by the rotation of the first cam member 3 or the second cam member 5, respectively. Each of the cam pins 24 (third cam pins) is inserted into the corresponding circumferential groove 53 of the second cam member 5 and the circumferential groove 33 of the first cam member 3 and provided on the peripheral wall 21 of the main body 2. By being fixed in the concave hole 25, the first and second cam members 3, 5 can be rotated around the central axis. Each of the cam pins 715 (fourth cam pins) is inserted into the arc-shaped slot 714 of the lens frame 71 and fixed to a concave hole (not explicitly indicated by a reference numeral) provided in the distal end surface of the inner peripheral wall 721 of the cylindrical frame 72. Thus, the lens frame 71 is slidably connected to the cylindrical frame 72.

  With the above configuration, the focusing operation of the zoom lens device 1 will be described with reference to FIGS. 3 to 6 schematically show the positional relationship between the main body 2, the lens 73, and the spiral grooves 32 and 52 when the zoom lens apparatus 1 performs focusing. For ease of explanation, it is assumed in each drawing that the optical axis X is always on the central axis of the main body and the central axis of the main configuration.

  In FIG. 3, assuming that the lens 73 is separated from the right side of the main body 2 by a distance L1, the cam pins 713 and 724 are arranged in the circumferential direction substantially perpendicular to the optical axis direction in the corresponding spiral grooves 32 and 52 having different spiral angles. Concentric.

  When the drive gear 63 is driven by the motor 61 of the second drive means 6 through the reduction gear 62, for example, counterclockwise, for example, at a circumferential angle α1, as shown in FIG. 4, the drive gear 63 and the second cam member are driven. The second cam member 5 is rotated in accordance with the meshing relationship with the inner tooth portion 54 of the fifth gear 5 to shift the second spiral groove 52 by the circumferential angle α1, and at the same time, the cam pin 724 of the cylindrical frame 72 is inserted into the second spiral groove 52. Is moved to move the lens frame 71 connected to the cylindrical frame 72 from the right side of the main body 2 to the right, for example, by a distance L2 along the optical axis direction. The movement of the lens frame 71 causes the cam pin 713 to slide into the first spiral groove 32 by a distance L2. However, since the first cam member 3 is engaged with the first drive means 4 and does not move, the spiral groove Due to the difference between the rising angles γ1 and γ2 of 32 and 52, the circumferential angle difference between the cam pins 713 and 724 located at the distance L2 is β1, and the lens frame means 7 the lens frame 71 has a circumferential angle in the annular slot 714. β1 is slid.

  As described above, when the second cam member 5 is rotated, the rising angle γ2 of the second helical groove 52 is larger than that of the first helical groove 32. Therefore, the lens frame means 7 has a second rising angle γ2 that is large. It is slid at high speed by the spiral groove 52.

  Next, when the drive gear 43 is driven by the motor 41 of the first drive means 4 through the reduction gear 42, for example, in the clockwise direction, for example, by rotating the circumferential angle α2 as shown in FIG. 5, as shown in FIG. The first cam member 3 is rotated by the meshing relationship with the internal tooth portion 34 of the member 3 to shift the first spiral groove 32 by the circumferential angle α2, and at the same time, the cam pin of the lens frame 71 in the first spiral groove 32. 713 is slid, and the cylindrical frame 72 connected to the lens frame 71 is moved to the right so as to be, for example, a distance L3 to the right side of the main body 2 along the central axis direction. The cam pin 724 is slid into the second spiral groove 52 by the movement of the cylindrical frame 72. However, since the second cam member 5 is engaged with the second driving means 6 and does not move, the spiral grooves 32, 52 are engaged. Because of the difference between the rising angles γ 1 and γ 2, the circumferential angle difference between the cam pins 713 and 724 located at the distance L 2 is β 2, and the lens frame 71 of the lens frame means 7 slides in the annular slot 714 at the circumferential angle β 2. Is moved (FIG. 6).

  As described above, when the first cam member 3 is rotated, the rising angle γ1 of the first helical groove 32 is smaller than that of the second helical groove 52. Therefore, the lens frame means 7 has the first rising angle γ1 smaller. The spiral groove 32 slides at a low speed.

  As described above, in the zoom lens device 1 of the present invention, the driving units 4 and 6 determine different driving forces and deceleration rates according to the plurality of cam members 3 and 5 having the spiral grooves 32 and 52 having different spiral angles. By independently driving the cam members 3 and 5, focusing can be performed at different speeds, so that it is possible to perform focusing accurately with both backlash removal and focusing accuracy.

  As described above, according to the present invention, it is possible to provide a zoom lens device that can perform focusing with high accuracy while reducing the influence of backlash as much as possible.

It is a disassembled perspective view which shows schematic structure of the zoom lens apparatus of this invention. It is an assembly longitudinal cross-sectional view of the zoom lens device. It is a figure which shows schematically the positional relationship of the main body in the same assembly state, a lens, and both spiral grooves. It is a figure which shows roughly the positional relationship of the main body at the time of the focusing, a lens, and both spiral grooves. It is a figure which shows roughly the positional relationship of the main body at the time of the focusing, a lens, and both spiral grooves. It is an assembly longitudinal cross-sectional view at the time of the focusing. It is a disassembled perspective view of the conventional zoom lens apparatus. It is an assembly longitudinal cross-sectional view of the zoom lens device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Zoom lens apparatus 2 Cylindrical main body 21 Perimeter wall 22 2nd through-hole 23 1st through-hole 24 Cam pin 25 Recessed hole 3 1st cam member 31 1st cyclic | annular wall 311 Tip part 312 Inner peripheral surface 32 1st Spiral groove 33 1st circumferential groove 34 1st inner tooth part 4 1st drive means 41 Motor 42 Reduction gear 43 Drive gear 5 2nd cam member 51 2nd annular wall 511 Tip part 512 Inner peripheral surface 52 Second spiral groove 53 Second circumferential groove 54 Second inner tooth portion 6 Second drive means 61 Motor 62 Reduction gear 63 Drive gear 7 Lens frame means 71 Lens frame 711 Central opening 712 Outer peripheral surface 713 Cam pin 714 Annular Slot (circumferential groove)
715 Cam pin 716 Recessed hole 717 End face 72 Cylindrical frame 721 Inner peripheral wall 722 Outer peripheral wall 723 Clearance 724 Cam pin 725 Through hole 73 Lens γ1, γ2 Rise angle θ1, θ2 Helical angles α1, α2, β1, β2 Circumferential angle X Central axis (light axis)

Claims (9)

A cylindrical body having a peripheral wall centered on the optical axis;
A cylindrical body having an optical axis as a central axis, one end of which has a first annular wall rotatably provided on the outer peripheral wall of the main body, and the first annular wall has a circumferential component and light. A first cam member through which a plurality of first spiral grooves having an axial component are provided;
First driving means connected to the first cam member so as to be rotationally driven;
A cylindrical shape having an optical axis as a central axis and being loosely fitted in the first cam member, and having one end portion rotatably provided on the outer peripheral wall of the main body; A second cam member having a circumferential component and an optical axis component in the second annular wall, and a plurality of second spiral grooves having a spiral angle different from that of the first spiral groove; ,
Second driving means connected to the second cam member so as to be rotationally driven;
An annular portion having an optical axis as a central axis is provided inside the first annular wall of the first cam member, and the outer peripheral wall and the first and second cam members are loosely fitted and held in a nested manner. A cylindrical portion formed of a slightly thicker inner peripheral wall with a gap capable of being held holds the ring portion in a freely movable manner near the opening end, and the first cam member loosely fitted in the gap is provided in the ring portion. A plurality of first cam pins that are movably inserted into the first spiral groove are planted, and the cylindrical portion is inserted into each second spiral groove of the second cam member loosely fitted in the gap. A zoom lens device comprising: a plurality of second cam pins implanted; and a lens frame means for holding a lens inside the ring portion or the cylindrical portion. The first and second annular walls of each of the first and second cam members have a plurality of first and second circumferences that restrict rotation of the first and second cam members along the circumferential direction. A groove penetrated,
2. The zoom lens device according to claim 1, wherein the main body includes a third cam pin that is inserted into the first and second circumferential grooves and fixed to the peripheral wall.   2. The zoom lens device according to claim 1, wherein the spiral angle of the first spiral groove is larger than the spiral angle of the second spiral groove. 2. The lens according to claim 1, wherein the lens is mounted in an annular portion of the lens frame means, and the first cam pin is inserted into the first spiral groove and fixed to the outer peripheral surface of the annular portion. The zoom lens device according to 1.
  The ring portion of the lens frame means is provided with a plurality of circumferential grooves penetrating in the optical axis direction, and the cylindrical portion is provided with a plurality of fourth cam pins inserted through the circumferential groove. The zoom lens device according to claim 4. The second cam pin is slidably inserted into the outer peripheral wall of the cylindrical portion and the second spiral groove of the second cam member,
6. The zoom lens device according to claim 5, wherein the fourth cam pin is fixed to the inner peripheral wall of the cylindrical portion through the circumferential groove of the ring portion of the lens frame means. In the peripheral wall of the main body, a first through hole is formed in the vicinity of one end of the peripheral wall, and a second through hole is opened away from one end of the peripheral wall,
On the inner peripheral surface of each one end of each of the first and second cam members, first and second inner teeth are ringed,
The first driving means is provided in the main body, and is connected to the motor, a reduction gear that is connected to the motor and adjusts driving force from the motor, and is connected to the reduction gear and the first through hole. A drive gear that meshes with the first internal tooth portion of the first cam member via the first cam member and transmits the driving force output from the motor to the first cam member,
The second driving means is provided on the main body, and is connected to the motor, a reduction gear connected to the motor to adjust a driving force from the motor, the reduction gear, and the second penetration. 2. The driving gear according to claim 1, further comprising: a driving gear that meshes with the second inner tooth portion through a hole and that transmits a driving force output from the motor to the second cam member. Zoom lens device. 2. The zoom lens apparatus according to claim 1, wherein the first driving unit drives the first cam member to limit a rotation angle in a circumferential direction.
2. The zoom lens device according to claim 1, wherein the second driving unit drives the second cam member to limit a rotation angle in a circumferential direction.

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