Optical device

Abstract

[Problem] To provide an optical device in which it is possible to reduce sound generated when moving a lens while improving the efficiency of an output such as a driving force of a lens holding frame with respect to an input from a power source. [Solution] This optical device comprises: a holding member that is movable in an optical axis direction; a lead screw that extends in the optical axis direction and is rotationally driven by an actuator; a power transmission member that is provided with an engagement part which engages with the lead screw and transmits power in the optical axis direction in response to the rotation of the lead screw; a connection member that is provided with a support part which rotatably and slidably supports the power transmission member, and that is connected to the holding member; a contact member that comes into contact with the power transmission member; a first biasing means that biases the contact member from the holding member toward the power transmission member in the optical axis direction; and a second biasing means that biases the power transmission member toward the lead screw. In the optical axis direction, the power transmission member is biased toward the connection member by the contact member, and in the optical axis direction, the connection member is biased toward the holding member by the power transmission member.

Description

optical device

[0001] The present invention relates to an optical device.

[0002] In a lead screw / rack power transmission mechanism that converts the rotational force of a lead screw into a linear force in the direction of the rotation axis, a sliding friction load is generated between the lead screw and the rack, resulting in reduced drive efficiency. Patent Document 1 discloses a configuration in which a moving body connected to a lens holding frame supports a circular member using a rotating rolling element such as a bearing, and the circular member engages with the lead screw, causing the lead screw and the circular member to roll and become a rolling resistance load, thereby reducing the load on the power source. Patent Document 2 also discloses a configuration in which a roller is pivotally supported on an optical head, the roller engages with the lead screw, and the lead screw and the roller roll and become a rolling resistance load, thereby reducing the load on the power source.

[0003] International Publication No. 2023 / 048093 Japanese Utility Model Application Laid-Open No. 61-040770

[0004] However, the configuration of Patent Document 1 uses rolling elements such as bearings, which tend to generate rolling noise from the rolling balls and increase the driving noise. Furthermore, incorporating rolling elements such as bearings results in an increased device size. Furthermore, Patent Document 2 does not specifically describe the specific roller support configuration.

[0005] The present invention aims to provide an optical device that can reduce noise when moving a lens while improving the efficiency of the output of driving force, etc., of a lens holding frame in response to input of torque, etc., from a power source.

[0006] An optical device according to one aspect of the present invention comprises a holding member movable in the optical axis direction of the lens, a lead screw extending in the optical axis direction and driven to rotate by an actuator, a power transmission member having an engagement portion that engages with the lead screw and transmits power in the optical axis direction in response to rotation of the lead screw, a connecting member having a support portion that rotatably supports the power transmission member and is connected to the holding member, an abutment member that abuts the power transmission member, a first biasing means that urges the abutment member from the holding member toward the power transmission member in the optical axis direction, and a second biasing means that urges the power transmission member toward the lead screw, wherein in the optical axis direction the power transmission member is urged toward the connecting member by the abutment member, and in the optical axis direction the connecting member is urged toward the holding member by the power transmission member.

[0007] According to the present invention, an optical device can be provided that can reduce noise when moving a lens while improving the efficiency of the output of the driving force, etc., of the lens holding frame in response to the input of torque, etc., from a power source.

[0008] FIG. 1 is an explanatory diagram of an optical device according to a first embodiment; FIG. 2 is a perspective view of a power transmission member according to the first embodiment; FIG. 3 is an exploded perspective view and a perspective view of the power transmission member according to the first embodiment; FIG. 4 is an explanatory diagram of the power transmission member according to the first embodiment; FIG. 5 is an explanatory diagram of loss reduction according to the first embodiment; FIG. 6 is an explanatory diagram of an optical device according to a second embodiment; FIG. 7 is a cross-sectional view of the power transmission member according to the second embodiment; FIG. 8 is an explanatory diagram of an optical device according to a third embodiment; FIG. 9 is a perspective view of a power transmission member according to the third embodiment; FIG. 10 is an exploded perspective view and a perspective view showing the configuration of the power transmission member according to the third embodiment; FIG. 11 is an explanatory diagram of a power transmission member according to the third embodiment; FIG. 12 is an explanatory diagram of an energized state according to the third embodiment.

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, identical components are designated by the same reference numerals, and redundant descriptions will be omitted. [First Embodiment] (1-1) Overall Configuration FIG. 1(a) is a perspective view of the optical device 100 excluding the fixed barrel 101, and FIG. 1(b) is a cross-sectional view of the optical device 100. FIGS. 2(a) and 2(b) are enlarged perspective views of the power transmission member 110, excluding the lead screw 108, as viewed from different directions. In this embodiment, the direction parallel to the optical axis of the lens 102 (optical axis direction) is the X1 direction, the direction perpendicular to the X1 direction is the Y1 direction, the up-down direction of the optical device 100 is the Z1 direction, and the direction perpendicular to the X1 and Y1 directions is the Z1 direction, as indicated by arrows in the drawings.

[0010] The optical device 100 includes a lens holding frame (holding member) 103 that holds a lens 102, and a cylindrical main guide bar 104 and a sub guide bar 105 whose axial direction is parallel to the X1 direction and linearly guides the lens holding frame 103 in the optical axis direction of the lens 102. The optical device 100 also includes a sheet metal part 107, a power source (actuator) 106 fixed to the sheet metal part 107, and a lead screw 108 whose rotational axis direction is parallel to the X1 direction (extending in the X1 direction) and connected to the power source 106. When power is input to the power source 106 from a power supply or the like (not shown), the lead screw 108 is driven to rotate. In this embodiment, a stepping motor is used as the power source 106, but a different power source may be used as long as it can drive the lead screw 108 to rotate. Furthermore, the optical device 100 has a connecting member 109 connected to the lens holding frame 103, a power transmission member 110 rotatably and slidingly supported on the connecting member 109, an abutment member 111 abutting against the power transmission member 110, and a compression torque spring 112.

[0011] Both ends of the main guide bar 104 and the sub guide bar 105 are fixed to fixing portions (not shown) of the fixed lens barrel 101. In addition, the sheet metal portion 107 and the power source 106 fixed to the sheet metal portion 107 are fixed to the fixed lens barrel 101.

[0012] The lens holding frame 103 has guide holes 103a and 103b that engage with the main guide bar 104 and a guide groove 103u that abuts against the sub-guide bar 105. The lens holding frame 103 is supported by the guide holes 103a and 103b and the main guide bar 104 so as to be movable in the X1 direction, and the guide groove 103u and the sub-guide bar 105 prevent the main guide bar 104 from rotating around its axis. In this embodiment, the main guide bar 104 and the sub-guide bar 105 are used as guide means for the lens holding frame 103, but a different configuration may be used as long as it can support the lens holding frame 103 so as to be movable in the X1 direction. The lens holding frame 103 also has connecting holes 103c and 103d that are parallel to the X1 direction and connect to a connecting member 109. The connecting member 109 is connected so as to be rotatable around the axis of the connecting holes 103c and 103d.

[0013] 3(a) and 3(b) are exploded perspective views of the components around the power transmission member 110, as viewed from different directions. FIGS. 3(c) and 3(d) are perspective views of the assembled components of FIGS. 3(a) and 3(b), respectively. FIG. 4(a) is an enlarged view of the power source 106 and its surroundings of the optical device 100, excluding the fixed barrel 101, as viewed from the direction opposite to the X1 direction. FIGS. 4(b) and 4(c) are cross-sectional views taken along lines A-A and B-B, respectively, of FIG. 4(a). FIG. 4(d) is a cross-sectional view taken along line B-B, showing a case where the support structure for the power transmission member 110 is different.

[0014] The connecting member 109 includes a sliding support shaft portion 109a and a sliding support surface portion 109b that support the power transmission member 110 so that the power transmission member 110 can slide and rotate about an X2 axis parallel to the X1 direction. The sliding support shaft portion 109a and the sliding support surface portion 109b function as a support portion that supports the power transmission member 110 so that the power transmission member 110 can slide and rotate. The connecting member 109 also includes connecting shaft portions 109c and 109d that are connected to the connecting hole portions 103c and 103d so that the power transmission member 110 can slide and rotate about an X3 axis parallel to the X1 direction. The connecting member 109 also includes an engaging shaft portion 109e that engages with the abutting member 111, a rotation restricting portion 109g that restricts relative rotation with the abutting member 111, and a biasing portion 109f to which the biasing force of the torque spring portion 112b of the compression torque spring 112 is transmitted. Furthermore, the connecting member 109 includes a conical portion 109h that abuts against the lens holding frame 103 in the X1 direction.

[0015] The power transmission member 110 includes a sliding hole portion 110a and a sliding surface portion 110b that are rotatably and slidingly supported on the connecting member 109 around the X2 axis, and a sliding surface portion 110c that is rotatably and slidingly brought into contact with the contact member 111. The power transmission member 110 also includes a full-circumferential tooth portion (engagement portion) 110d that meshes with the thread portion of the lead screw 108.

[0016] The abutment member 111 includes an engagement hole portion 111a that engages with the connecting member 109 on the X3 axis, and a rotation restricting portion 111c that restricts relative rotation around the X3 axis with the connecting member 109. The abutment member 111 also includes a sliding abutment surface portion 111b that rotatably and slidingly abuts against the power transmission member 110, and a spring shaft portion 111d into which the compression spring portion 112a of the compression torque spring 112 is incorporated.

[0017] The compression torque spring 112 includes a compression spring portion (first biasing means) 112a and a torque spring portion (second biasing means) 112b. The compression spring portion 112a biases the abutting member 111 from the lens holding frame 103 toward the power transmission member 110 in the X1 direction. The torque spring portion 112b biases both the lens holding frame 103 and the connecting member 109 in a direction perpendicular to the X1 direction, which is orthogonal to the optical axis, and biases the power transmission member 110 toward the lead screw 108.

[0018] The biasing state of each component in a direction perpendicular to the X1 direction will be described below. The connecting hole portions 103c and 103d are connected to the connecting shaft portions 109c and 109d so as to be rotatable about the X3 axis, and are biased by the torque spring portion 112b toward the offset portion 109f with a biasing force S1 (FIG. 3C). Due to the biasing force S1, the sliding support shaft portion 109a is biased toward the side surface of the sliding hole portion 110a of the power transmission member 110 with a biasing force S2 (FIG. 4C). Furthermore, due to the biasing force S2, the full-circumferential tooth portion 110d is biased toward the thread portion of the lead screw 108 with biasing forces S3 and S3' (FIG. 4C). At this time, rotation of the connecting member 109 about the X3 axis causes the full-circumferential tooth portion 110d to mesh with the lead screw 108. As described above, by biasing the connecting member 109 with the torque spring portion 112b, the thread portion of the lead screw 108 and the full-circumferential teeth portion 110d can be meshed without any play.

[0019] Furthermore, torque spring portion 112b biases lens holding frame 103 against main guide bar 104 and sub guide bar 105. This makes it possible to suppress backlash between guide holes 103a, 103b and main guide bar 104 in a direction perpendicular to the X1 direction, and to suppress backlash between guide groove portion 103u and sub guide bar 105 in a direction perpendicular to the X1 direction.

[0020] The biasing state of each component in the X1 direction will now be described. The abutment member 111 engages with the engagement shaft portion 109e via the engagement hole portion 111a. Rotation around the X3 axis is restricted by the rotation restricting portions 109g and 111c, allowing movement only in a direction parallel to the X3 axis. The spring shaft portion 111d is biased by the compression spring portion 112a with a biasing force S4 (see FIG. 4B). The biasing force S4 causes the abutment member 111 to move in a direction parallel to the X3 axis, and the sliding abutment surface portion 111b is biased toward the sliding surface portion 110c. Because the other end of the compression spring portion 112a abuts against the lens holding frame 103, the lens holding frame 103 receives a biasing force S4' in the X1 direction opposite to the biasing force S4. Furthermore, the biasing force S5 applied to the sliding surface portion 110c biases the sliding surface portion 110b toward the sliding support surface portion 109b. Furthermore, the conical portion 109h is urged toward the connecting hole portion 103c by the urging force S6 applied to the sliding support surface portion 109b. As described above, the compression spring portion 112a urges the connecting member 109, the power transmission member 110, and the abutting member 111 toward the lens holding frame 103 in the X1 direction without any backlash.

[0021] A power transmission member 110' having a different support configuration from the power transmission member 110 of FIG. 4(d) will be described below. The power transmission member 110' has sliding shaft portions 110b' and 110c'. The sliding shaft portions 110b' and 110c' abut against a conical bearing 109a' provided on the connecting member 109' and a conical bearing 111b' on the abutment member 111', respectively. The conical bearing 109a' functions as a support portion that rotatably and slidingly supports the power transmission member 110. In the configuration of FIG. 4(d), the biasing state in the X1 direction and the direction perpendicular to the X1 direction is the same as the state in FIG. 3 and FIGS. 4(a) to 4(c), so a description thereof will be omitted.

[0022] The support structure for the power transmission member may be the structure shown in Fig. 4(c) or the structure shown in Fig. 4(d) as long as the structure allows rotatable support on an abutment surface that includes the rotation axis of the power transmission member. It is desirable that the abutment surface be located near the center of the rotation axis of the power transmission member, as this will increase the effect of load reduction, which will be described later.

[0023] The engagement configuration between the power transmission member 110 and the lead screw 108 will now be described. The power transmission member 110 has a full-circumferential toothed portion 110d on its outer diameter side. The full-circumferential toothed portion 110d is biased to mesh with the threads of the lead screw 108, which is driven to rotate by the power source 106. The full-circumferential toothed portion 110d is configured to connect around the entire circumference of the outer diameter side of the power transmission member 110, and is biased to always mesh with the lead screw 108 even when the power transmission member 110 slides and rotates relative to the connecting member 109. However, the engagement configuration between the lead screw 108 and the power transmission member 110 may have a different shape as long as the lead screw 108 and the power transmission member 110 are configured to mesh with each other. As described above, the power transmission member 110 is biased to rotate around the X2 axis from the sliding support shaft portion 109a by the sliding hole portion 110a, and is biased to rotate so as to be sandwiched between the sliding support surface portion 109b and the sliding abutment surface portion 111b.

[0024] With the above configuration, when the lead screw 108 is rotationally driven by the power source 106, the thread portion of the lead screw 108 appears to move in the direction of the rotation axis of the lead screw 108. Then, the full-circumferential teeth portion 110d that mesh with the thread portion rolls and rotates while meshing with the lead screw 108, and the lens 102, lens holding frame 103, lens connecting member 109, power transmission member 110, abutment member 111, and compression torque spring 112 move in the X1 direction. The configuration of this embodiment satisfies the following conditional expression (1).

[0025] T1>T2 (1) Here, T1 is the rotational resistance torque acting on the full-circumferential toothed portion 110d when the power transmission member 110 engages with the lead screw 108 and slides. T2 is the rotational resistance torque acting on the sliding support shaft portion 109a when the connecting member 109 and the power transmission member 110 rotate relatively around the X2 axis. By satisfying conditional expression (1), the power transmission member 110 does not slide while engaging with the lead screw 108, but rather rolls and rotates while engaging with the lead screw 108, and rotates relative to the connecting member 109. For example, a case will be described where the friction coefficient μ1 between the power transmission member 110 and the lead screw 108 is the same as the friction coefficient μ2 between the power transmission member 110 and the connecting member 109, the diameter of the sliding hole portion 110a is D1, and the diameter of the full-circumferential toothed portion 110d is D2. 4(c), the rotational resistance torque T1 is proportional to the sum of the diameter D2 and the biasing forces S3 and S3', and the rotational resistance torque T2 is proportional to the diameter D1 and the biasing force S2. Since the diameter D2 is larger than the diameter D1 and the sum of the biasing forces (normal forces) S3 and S3' is larger than the biasing force S2 (details will be described later), the rotational resistance torque T1 is larger than the rotational resistance torque T2, and the power transmission member 110 rotates relative to the connecting member 109.

[0026] (1-2) Loss Reduction First, the forces acting on the power transmission member 110 of this embodiment will be described. FIG. 5( a) shows forces F1 and F6 that the power transmission member 110 receives from the connecting member 109, forces F2 and F3 that the lead screw 108 receives, and force F8 that the power transmission member 110 receives from the abutting member 111. These forces are generated by the biasing forces S1 and S4 of the compression torque spring 112. FIG. 5( b) is a cross-sectional view taken along line CC in FIG. 5( a). FIG. 5( b) also shows a resistance force F4 that is generated when the lead screw 108 rotates in direction G1 and the power transmission member 110 rotates in direction G2 while receiving force F1, and a tangential force F5 required for the lead screw 108 to rotationally drive the power transmission member 110. FIG. 5( c) is a cross-sectional view taken along line D-D in FIG. 5( a). Figure 5(c) shows a resistance force F7 that is generated when the lead screw 108 rotates in direction G1 and the power transmission member 110 rotates in direction G2 while receiving force F6. Figure 5(d) is a cross-sectional view taken along line E-E in Figure 5(a). Figure 5(d) shows a resistance force F9 that is generated when the lead screw 108 rotates in direction G1 and the power transmission member 110 rotates in direction G2 while receiving force F8.

[0027] Loss reduction will be explained below. Here, D0 is the diameter of the lead screw 108. D1 is the diameter of the slide hole portion 110a. D2 is the diameter of the full-circumferential tooth portion 110d that meshes with the lead screw 108. D3 is the diameter of the area where the connecting member 109 and slide surface portion 110b abut. D4 is the diameter of the area where the abutting member 111 and slide surface portion 110c abut. As shown in FIG. 4(c), the slide hole portion 110a has two diameters, D1 and D1', but since the diameters D1 and D1' are almost the same, only the diameter D1 will be used in the following explanation for simplicity.

[0028] The force F1 is a force that the connecting member 109 applies to the power transmission member 110 when the torque spring portion 112b biases the offset portion 109f. The forces F2 and F3 are forces that the lead screw 108 applies to the power transmission member 110 when the power transmission member 110 biases the lead screw 108 by force F1. Furthermore, the forces F2 and F3 are forces in a direction perpendicular to the engagement surface because the lead screw 108 and the full-circumferential toothed portion 110d engage with each other at a thread opening angle H1. In this embodiment, the thread opening angle H1 of the lead screw 108 is 60°, and the forces F2 and F3 have the same magnitude as force F1 due to the balance of the forces.

[0029] 5B, the rotational resistance torque of the power transmission member 110 about the X2 axis generated by the force F1 will be described. When the lead screw 108 is rotationally driven in the direction G1, the configuration of this embodiment satisfies conditional expression (1), and therefore the power transmission member 110 rotates while engaging with the lead screw 108. At this time, when the power transmission member 110 rotates in the direction G2 while receiving the force F1, a resistance force F4 is generated between the connecting member 109 and the power transmission member 110. At this time, the rotational resistance torque T4 of the power transmission member 110 about the X2 axis caused by the resistance force F4 is expressed by the following equation (2).

[0030] T4=F4×(D1 / 2) (2) Furthermore, the tangential force F5 required for the lead screw 108 to rotationally drive the power transmission member 110 that generates the rotational resistance torque T4 satisfies the following conditional expression (3).

[0031] F5>F4 / (D2 / D1) (3) From the above, the rotational driving force T5 required for the lead screw 108 to rotationally drive the power transmission member 110 is expressed by the following equation (4).

[0032] T5=F5×D0 / 2 (4) From the conditional expressions (3) and (4), the rotational driving force T5 satisfies the following conditional expression (5) using the resistance force F4.

[0033] T5>(F4 / (D2 / D1))×(D0 / 2) (5) From conditional expression (5), the rotational driving force T5 required for the lead screw 108 to rotate the power transmission member 110 is reduced by the ratio of the diameter D2 to the diameter D1. This means that the resistance force F4 at the diameter D1 generated between the coupling member 109 and the power transmission member 110 is reduced by the ratio of the diameter D2 to the diameter D1 at the position of the diameter D2 of the full-circumferential tooth portion 110d. Therefore, the tangential force F5 required for the lead screw 108 to rotate the power transmission member 110 is reduced by the ratio of the diameter D2 to the diameter D1. However, if the diameter D2 is increased, the ratio of the diameter D2 to the diameter D1 increases and the tangential force F5 is reduced, but this increases the moment of inertia of the power transmission member 110 and the size of the optical device 100. Therefore, it is necessary to set an appropriate value for the ratio of the diameter D2 to the diameter D1. Here, it is desirable to configure the ratio of diameter D2 to diameter D1 to satisfy the following conditional expression (6) so that the optical device 100 does not become large and the moment of inertia of the power transmission member 110 does not increase too much.

[0034] 1<D2 / D1<100 (6) Hereinafter, with reference to Figures 5(a) and 5(c), the rotational resistance torque of power transmission member 110 about the X2 axis, which is generated by force F6, will be described. Force F6 is a force that power transmission member 110 receives from connecting member 109, and is the force with which compression spring portion 112a urges contact member 111. When power transmission member 110 rotates in direction G2 while receiving force F6, resistance force F7 is generated between connecting member 109 and power transmission member 110. At this time, rotational resistance torque T7 of power transmission member 110 about the X2 axis due to resistance force F7 is expressed by the following equation (7).

[0035] T7 = F7 × (D3 / 2) (7) By making the sliding support surface portion 109b spherical, the diameter D3 becomes almost zero, and the rotational resistance torque T7 also becomes a very small value (almost zero). As described above, the resistance force F4 due to the force F1 generated at the diameter D1 is reduced at the position of the diameter D2 by the ratio of the diameter D2 to the diameter D1. Similarly, the resistance force F7 at the diameter D3 generated between the connecting member 109 and the power transmission member 110 is reduced at the position of the diameter D2 of the full-circumferential tooth portion 110d by the ratio of the diameter D2 to the diameter D3. Therefore, the rotational resistance torque T7 has almost no effect on the tangential force F5 required for the lead screw 108 to rotate the power transmission member 110, and can therefore be ignored.

[0036] 5(a) and 5(d), the rotational resistance torque of the power transmission member 110 about the X2 axis, which is generated by force F8, will be described. Force F8 is a force that the power transmission member 110 receives from the abutting member 111, and is a force of the same magnitude as the force with which the compression spring portion 112a urges the abutting member 111. When the power transmission member 110 rotates in direction G2 while receiving force F8, a resistance force F9 is generated between the power transmission member 110 and the abutting member 111. At this time, the rotational resistance torque T9 of the power transmission member 110 about the X2 axis due to the resistance force F9 is expressed by the following equation (8).

[0037] T9 = F9 × (D4 / 2) (8) By making the sliding surface portion 110c spherical, the diameter D4 becomes almost zero, and the rotational resistance torque T9 also becomes a very small value (almost zero). As described above, the resistance force F4 due to the force F1 generated at the diameter D1 is reduced at the position of the diameter D2 by the ratio of the diameter D2 to the diameter D1. Similarly, the resistance force F9 at the diameter D4 generated between the power transmission member 110 and the abutting member 111 is reduced at the position of the diameter D2 of the full-circumferential tooth portion 110d by the ratio of the diameter D2 to the diameter D4. Therefore, the rotational resistance torque T9 has almost no effect on the resistance force F9 and can be ignored.

[0038] The rotational resistance torque will be described below in a hypothetical configuration in which the power transmission member 110 does not rotate. If the power transmission member 110 is fixed to the connecting member 109 and the lead screw 108 is driven to rotate, the power transmission member 110 engages with the threads of the lead screw 108, generating a resistance force, such as friction, against the forces F2 and F3 shown in FIG. 5A. The generated resistance force is the tangential force of the lead screw 108 required to drive the power transmission member 110 to rotate. For example, if the coefficient of friction between the lead screw 108 and the power transmission member 110 is μ, a frictional force of (F2 + F3) × μ is generated. Furthermore, if the open angle H1 of the threads is 60°, as described above, the forces F1, F2, and F3 are equal, and the frictional force is 2 × F1 × μ. In this case, the torque required to rotate the lead screw 108 is greater than the value F1 × μ × D0.

[0039] In this embodiment, because the lead screw 108 and the power transmission member 110 rotate by rolling, resistance forces such as friction due to forces F2 and F3 are not generated, but resistance force F4 due to friction due to force F1 is generated. If the coefficient of friction between the connecting member 109 and the power transmission member 110 is μ, force F4 is F1×μ. In this case, the rotational driving force T5 required for the lead screw 108 to rotationally drive the power transmission member 110 is a value greater than {(F1×μ) / (D2 / D1)}×(D0 / 2) from conditional expression (5).

[0040] As described above, when the power transmission member 110 is configured to be rotatable, it is possible to rotate the lead screw 108 and drive the lens holding frame 103 in the X1 direction with a smaller load than when the power transmission member 110 is fixed. This makes it possible to reduce the resistance forces F4, F7, and F9 by the values ​​D2 / D1, D2 / D3, and D2 / D4, respectively, and reduce the loss that occurs when transmitting force from the lead screw 108 to the power transmission member 110. Therefore, it is possible to increase the output of the driving force, etc., of the lens holding frame 103 relative to the torque input transmitted from the power source 106 to the lead screw 108, making it possible to provide an optical device 100 with improved drive efficiency.

[0041] The following describes the effects obtained by rotatably and slidingly supporting the power transmission member 110 between the connecting member 109 and the abutting member 111. In this embodiment, the sliding hole portion 110a is rotatably and slidingly supported by the connecting member 109 in the direction perpendicular to the X1 direction, and the sliding surface portions 110b and 110c are rotatably and slidingly supported in the X1 direction so as to be sandwiched between the connecting member 109 and the abutting member 111. Therefore, all of the support portions of the power transmission member 110 are sliding bearings, and there is no need to use a rolling structure such as a bearing. Therefore, even when the power transmission member 110 rotates, vibration noise and drive noise can be reduced, and the optical device 100 can be made smaller.

[0042] As described above, the configuration of this embodiment can provide a compact optical device with reduced vibration and drive noise while improving drive efficiency by reducing load loss in power transmission. [Second Embodiment] In this embodiment, only the configuration that differs from the first embodiment will be described, and a description of the common configuration will be omitted. Note that in this embodiment, parts, shapes, etc. are numbered in the 200s, but parts and shapes similar to those in the first embodiment are numbered with the same last two digits as in the first embodiment.

[0043] 6A is a perspective view of the optical device 200 excluding the fixed barrel 201, and FIG. 6B is a cross-sectional view of the optical device 200. In this embodiment, the direction parallel to the optical axis of the lens 202 (optical axis direction) is the X5 direction, which is perpendicular to the X5 direction, the up-down direction of the optical device 200 is the Y2 direction, and the direction perpendicular to the X5 direction and the Y2 direction is the Z2 direction, which are indicated by arrows in the figure.

[0044] The optical device 200 includes a lens holding frame 1203 that holds a lens 202, and a cylindrical main guide bar 204 and a sub guide bar 205 whose axial direction is parallel to the X5 direction and linearly guides the lens holding frame 203 in the optical axis direction of the lens 202. The optical device 200 also includes a sheet metal part 207, a power source 206 fixed to the sheet metal part 207, and a lead screw 208 whose rotational axis direction is parallel to the X5 direction and connected to the power source 206. When power is input to the power source 206 from a power source or the like (not shown), the lead screw 208 is driven to rotate. The optical device 200 also includes a connecting member 109 connected to the lens holding frame 203, and a sliding shaft member 213 fixed to the connecting member 209 by a fixing nut 214. Furthermore, the optical device 200 has a power transmission member 210 rotatably and slidingly supported on the sliding shaft member 213 , a contact member 211 that contacts the power transmission member 210 , and a compression torque spring 212 .

[0045] 7, the detailed shapes of the connecting member 209 and the sliding shaft member 213 and the effect obtained by configuring the sliding shaft member 213 as a separate part from the connecting member 209 will be described.

[0046] The connecting member 209 has an engagement hole 209i with which the sliding shaft member 213 engages, and a through-hole 209j through which the sliding shaft member 213 passes. The sliding shaft member 213 has a sliding support shaft portion 213a and a sliding support surface portion 213b that slidingly support the power transmission member 210 so that the power transmission member 210 can rotate about the X6 axis that is parallel to the X5 direction. The sliding shaft member 213 also has an engagement shaft portion 213c that engages with the connecting member 209, and a fixing screw portion 213d that is connected to the fixing nut 214.

[0047] The following describes the effects achieved by constructing the sliding shaft member 213 as a separate component from the connecting member 209. D5 is the diameter of the sliding hole portion 210a and the sliding support shaft portion 213a. D6 is the diameter of the full-circumferential tooth portion (engagement portion) 210d that meshes with the lead screw 208. As described above, the load can be reduced by the ratio of the diameter D6 to the diameter D5. By minimizing the diameter D5, the ratio of the diameter D6 to the diameter D5 can be increased, thereby enhancing the load reduction effect. In this embodiment, by constructing the sliding shaft member 213 from a high-strength component such as metal, the diameter D5 of the sliding support shaft portion 213a can be reduced, thereby further enhancing the load reduction effect. Furthermore, constructing the sliding shaft member 213 from a high-strength component such as metal can reduce wear due to the sliding rotation of the power transmission member 210 and reduce the coefficient of friction with the power transmission member 210. Furthermore, as in the first embodiment, there is no need to use a rolling structure such as a bearing, so vibration noise and driving noise can be reduced and the optical device 200 can be made smaller.

[0048] As described above, the configuration of this embodiment can provide a compact optical device 200 with reduced vibration and drive noise while improving drive efficiency by reducing load loss in power transmission. [Third Embodiment] (3-1) Overall Configuration In this embodiment, only the configuration that differs from the first and second embodiments will be described, and a description of the common configuration will be omitted. Note that in this embodiment, parts, shapes, etc. are numbered in the 300 range, but parts and shapes similar to those in the first embodiment are numbered with the same last two digits as in the first embodiment.

[0049] Fig. 8A is a perspective view of the optical device 300 excluding the fixed barrel 301, and Fig. 8B is a cross-sectional view of the optical device 300. Figs. 9A and 9B are enlarged perspective views of the power transmission member 310, excluding the lead screw 308, viewed from different directions. In this embodiment, the direction parallel to the optical axis of the lens 302 (optical axis direction) is the X8 direction, which is perpendicular to the X8 direction, the up-down direction of the optical device 300 is the Y3 direction, and the direction perpendicular to the X8 and Y3 directions is the Z3 direction, all of which are indicated by arrows in the figures.

[0050] The optical device 300 includes a lens holding frame 303 that holds a lens 302, and a cylindrical main guide bar 304 and a sub guide bar 305 whose axial direction is parallel to the X8 direction and linearly guides the lens holding frame 303 in the optical axis direction of the lens 302. The optical device 300 also includes a sheet metal part 307, a power source 306 fixed to the sheet metal part 307, and a lead screw 308 whose rotational axis direction is parallel to the X8 direction and connected to the power source 306. When power is input to the power source 306 from a power supply or the like (not shown), the lead screw 308 is driven to rotate. The optical device 300 also includes a connecting member 309 connected to the lens holding frame 303, a power transmission member 310 rotatably and slidingly supported by the connecting member 309, an abutting member 311 that abuts against the power transmission member 310, and a compression torque spring 312. Furthermore, the optical device 300 has a ball 315 incorporated into the abutting member 311 and a pinching torque spring (third biasing means) 316 .

[0051] The following describes the detailed shapes of the connecting member 309, the contact member 311, the compression torque spring 312, the ball 315, and the sandwiching torque spring 316. The other parts have the same shapes as in the first embodiment, so descriptions thereof will be omitted.

[0052] Figures 10(a) and 10(b) are exploded perspective views of the components around the power transmission member 310, viewed from different directions. Figures 10(c) and 10(d) are perspective views of the assembled parts of Figures 10(a) and 10(b), respectively. Figures 11(a) and 11(b) are cross-sectional views taken along lines F-F and G-G, respectively, of Figure 8(a).

[0053] In addition to the same configuration as in the first embodiment, the connecting member 309 includes an engagement shaft portion 309e into which the sandwiching torque spring 316 and the abutting member 311 are incorporated, and a rotation restricting portion 309g that restricts relative rotation between the connecting member 309 and the abutting member 311 around the X10 axis. The connecting member 309 also includes a sandwiching portion 309k to which the biasing force of the sandwiching torque spring 316 is transmitted.

[0054] In addition to the same shape as in the first embodiment, the abutting member 311 includes a rotation restricting portion (second abutting portion) 311c that restricts relative rotation with the connecting member 309 around the X10 axis, and a clamping portion 311i to which the biasing force of the clamping torque spring 316 is transmitted. The abutting member 311 also includes an abutting hole portion 311e with which the ball 315 engages and is fixed, and an abutting surface portion 311f that abuts against the ball 315 in the X8 direction. The abutting member 311 also includes a facing portion 311g that faces the power transmission member 310 so as to sandwich the lead screw 308 and is separated from the lead screw 308 by a predetermined gap. The abutting member 311 also includes a facing tooth portion (third abutting portion) 311h that is provided on the facing portion 311g and is engageable with the thread portion of the lead screw 308.

[0055] The compression torque spring 312 includes a compression spring portion (first biasing means) 312a and a torque spring portion (second biasing means) 312b. The compression spring portion 312a biases the contact surface portion (first contact portion) 311f of the contact member 311 from the lens holding frame 303 toward the power transmission member 310 in the X8 direction. The torque spring portion 312b biases both the lens holding frame 303 and the connecting member 309 in a direction perpendicular to the X8 direction, which is orthogonal to the optical axis, and biases the power transmission member 310 toward the lead screw 308.

[0056] The pinching torque spring 316 has a first end that biases the pinching portion 309k and a second end that biases the pinching portion 311i, and is incorporated into the engagement shaft portion 309e.

[0057] The biasing state of the components relative to each other will be described below. Note that the biasing state of each component in the direction perpendicular to the X8 direction by the torque spring portion 312b is the same as in the first embodiment, and therefore a description thereof will be omitted. Also, the biasing state of each component in the X8 direction by the compression spring portion 312a differs in that the ball 315 is integrally incorporated into and fixed to the abutting member 311 and abuts against the power transmission member 310, but the other configurations are the same as in the first embodiment, and therefore a description thereof will be omitted.

[0058] Because the engagement hole 311a is engaged with the engagement shaft 309e around the X10 axis, the abutting member 311 is rotatable around the X10 axis relative to the connecting member 309. In addition, the clamping torque spring 316 biases the clamping portions 309k and 311i, which biases the rotation restricting portions 309g and 311c so that they come into contact with each other. At this time, the forces at which the rotation restricting portions 309g and 311c come into contact with each other are indicated as F14' and F15' in the figure.

[0059] As a result, in the direction perpendicular to the X8 direction, the torque spring portion 312b urges the power transmission member 310 toward the lead screw 308, while the sandwiching torque spring 316 urges the abutting member 311 toward the power transmission member 310. At this time, as described above, the opposing portion 311g and the opposing tooth portion 311h are spaced apart from the lead screw 308 by a predetermined gap. The gap is configured to be smaller than the depth of engagement in the direction perpendicular to the X8 direction, where the full-circumferential tooth portion (engagement portion) 310d and the thread portion of the lead screw 308 engage with each other.

[0060] (3-2) Tooth Jumping: Tooth jumping, in which the full-circumferential tooth portion 310d exceeds the thread portion of the lead screw 308, will be described. First, with reference to FIG. 12, the biasing state of the power transmission member 310 when an external force in the X8 direction is applied to the lens 302 will be described. FIGS. 12(a) to 12(c) are enlarged views of region I in FIG. 11(b). FIGS. 12(a) and 12(b) show a state in which the power transmission member 310 does not separate from the lead screw 308 in a direction perpendicular to the X8 direction. FIG. 12(c) shows a state in which the power transmission member 310 separates from the lead screw 308 in a direction perpendicular to the X8 direction. FIG. 12(d) is a view of FIG. 12(c) viewed from the opposite direction of the X8 direction. FIG. 12(e) is an explanatory diagram of the biasing state immediately before tooth jumping, viewed from the opposite direction of the X8 direction. 12A, when no external force is acting on the lens 302, the power transmission member 310 receives a biasing force F11 from the connecting member 309 through the torque spring portion 312b, and normal forces F12 and F12' perpendicular to the inclined surface of the opening angle of the thread of the lead screw 308. The resultant force of the biasing force F11 and the normal forces F12 and F12' is in balance.

[0061] Next, a case where an external force F10 acts on the lens 302 will be described. When the external force F10 is generated on the lens 302 in the X8 direction, the external force F10 is transmitted to the lens holding frame 303, from the lens holding frame 303 to the connecting member 309 or the abutting member 311, and from the connecting member 309 or the abutting member 311 to the power transmission member 310. At this time, because the lead screw 308 is fixed in the X8 direction, the power transmission member 310 receives the external force F10 and a resistance force against the external force F10 from one of the inclined surfaces of the thread opening angle of the lead screw 308. Specifically, as shown in FIG. 12B , a normal force F12 perpendicular to the inclined surface of the thread opening angle of the lead screw 308 increases as a resistance force against the external force F10. Furthermore, because the resultant force of the normal forces F12 and F12′ in the direction perpendicular to the X8 direction is balanced with the biasing force F11, the normal force F12′ decreases. When the resultant force of normal forces F12 and F12' in the direction perpendicular to the X8 direction is equal to or less than the biasing force F11, the power transmission member 310 remains biased toward the lead screw 308 as shown in FIG. 12B. On the other hand, when the resultant force of normal forces F12 and F12' in the direction perpendicular to the X8 direction is greater than the biasing force F11, the power transmission member 310 moves away, climbing the slope of the opening angle of the threads of the lead screw 308. The power transmission member 310 then reaches the state shown in FIG. 12C, where the normal force F12' disappears. At this time, the connecting member 309 supporting the power transmission member 310 rotates about the X10 axis and moves away from the lead screw 308. As a result, the abutting member 311, biased toward the connecting member 309 by the rotation restricting portion 311c, also rotates about the X10 axis together with the connecting member 309. When the connecting member 309 and the abutment member 311 rotate around the X10 axis, the opposing teeth portion 311h abuts against the lead screw 308. As described above, in the state of Fig. 12(a) , the gap between the lead screw 308 and the opposing teeth portion 311h is smaller than the depth of engagement (engagement height) in a direction perpendicular to the X8 direction where the full-circumferential teeth portion 310d meshes with the thread portion of the lead screw 308. Therefore, as the connecting member 309 rotates around the X10 axis, the opposing teeth portion 311h abuts against the lead screw 308 before the full-circumferential teeth portion 310d completely clears the thread portion of the lead screw 308.

[0062] As a result, both the full-circumferential tooth portion 310d and the opposing tooth portion 311h abut against the lead screw 308, and the opposing tooth portion 311h receives a normal force F13 perpendicular to the inclined plane of the thread opening angle of the lead screw 308. As a result, the power transmission member 310 and the abutting member 311 receive normal forces F12 and F13 from the lead screw 308, respectively. Therefore, a separating force is generated that moves both the power transmission member 310 and the abutting member 311 away from the lead screw 308 in a direction perpendicular to the X8 direction. Meanwhile, when the opposing tooth portion 311h abuts against the lead screw 308, as shown in FIG. 11A, the biasing forces F14' and F15' of the sandwiching torque spring 316 decrease, and the biasing forces F14 and F15 shown in FIGS. 12B and 12C increase. This is because the biasing force of the sandwiching torque spring 316 not only acts as biasing forces F14' and F15' that sandwich the rotation restricting portions 309g and 311c, but also acts as biasing forces F14 and F15 that sandwich the lead screw 308 between the circumferential tooth portion 310d and the opposing tooth portion 311h. In the direction perpendicular to the X8 direction, when the normal forces F12 and F13 are smaller than the biasing forces F14 and F15, respectively, the circumferential tooth portion 310d and the opposing tooth portion 311h do not move any further away from the lead screw 308. On the other hand, in the direction perpendicular to the X8 direction, when the normal forces F12 and F13 are larger than the biasing forces F14 and F15, respectively, the circumferential tooth portion 310d and the opposing tooth portion 311h move further away from the lead screw 308. 12(d), all of the biasing force of the sandwiching torque spring 316 acts as biasing forces F14 and F15 that sandwich the lead screw 308 between the full-circumferential tooth portion 310d and the opposing tooth portion 311h. Also, the rotation restricting portions 309g and 311c no longer abut, and the biasing forces F14' and F15' no longer act. In this case, the full-circumferential tooth portion 310d and the opposing tooth portion 311h gradually climb up the slope of the opening angle of the thread of the lead screw 308, and eventually exceed the thread portion of the lead screw 308, causing a tooth jump phenomenon.

[0063] As described above, depending on the magnitude of the external force F10, the lead screw 308, the power transmission member 310, and the abutting member 311 can be in three engagement states. The first engagement state (first state) is a state in which the external force F10 is not applied in a direction perpendicular to the X8 direction and is not greater than a predetermined value. The resultant force of the normal forces F12 and F12', which increase or decrease due to the external force F10, is equal to or less than the biasing force F11. In this state, the full-circumferential tooth portion 310d is engaged with the thread portion of the lead screw 308, and the opposing tooth portion 311h is not abutting against the lead screw 308. This state also includes the absence of the external force F10. The second engagement state (second state) and the third engagement state are states in which the external force F10 is applied in a direction perpendicular to the X8 direction and is greater than a predetermined value. More specifically, the second engaged state is a state in which the resultant force of normal forces F12 and F12' in the direction orthogonal to the X8 direction is greater than the biasing force F11, the opposed teeth portion 311h abuts against the lead screw 308, and the normal forces F12 and F13 are equal to or smaller than the biasing forces F14 and F15, respectively. At this time, the full-circumferential teeth portion 310d engages with the thread portion of the lead screw 308, the opposed teeth portion 311h abuts against the lead screw 308, and tooth skipping is suppressed to the biasing forces F14 and F15. The third engaged state is a state in which the resultant force of normal forces F12 and F12' in the direction orthogonal to the X8 direction is greater than the biasing force F11, the opposed teeth portion 311h abuts against the lead screw 308, and the normal forces F12 and F13 are greater than the biasing forces F14 and F15, respectively. At this time, the full-circumferential tooth portion 310d and the opposing tooth portion 311h gradually run up the slope of the opening angle of the thread of the lead screw 308 and go beyond the thread portion, causing a tooth jump phenomenon.

[0064] Next, the desirable magnitude relationship between the biasing force F11 and the biasing force F14 or F15 will be described. When the lead screw 308 is rotated to move the lens 302 in the X8 direction, a small biasing force F11 reduces the driving load on the lead screw 308, so it is desirable to make the biasing force F11 as small as possible. Furthermore, in the second engagement state described above, the larger the biasing forces F14 and F15, the more effectively tooth skipping is suppressed, so it is desirable to make the biasing forces F14 and F15 large. However, if the biasing forces F14 and F15 are too large, tooth skipping will not occur even when a large external force F10 occurs when the optical device 300 is unintentionally dropped, and there is a risk of damage to the circumferential tooth portion 310d or the opposing tooth portion 311h. For this reason, it is desirable to design the spring so that the biasing forces F14 and F15 are between an upper limit value that anticipates component damage and a lower limit value that prevents tooth skipping up to the desired external force F10. Furthermore, if the biasing force F11 is made larger than the biasing force F14 or F15, the tooth jump suppression effect of the biasing forces F14 and F15 cannot be obtained even when transitioning from the first engagement state to the second engagement state. Therefore, in order to increase the tooth jump suppression effect, it is necessary to increase the biasing force F11 in the first engagement state, but this contradicts the desire to reduce the drive load. Therefore, in order to suppress tooth jumping with the biasing forces F14 and F15 and to reduce the drive load by reducing the biasing force F11, it is desirable that the biasing force F11 be smaller than the biasing forces F14 and F15.

[0065] Next, a configuration will be described in which, in the first engagement state, the opposing teeth portion 311h can be separated from the lead screw 208 with a precise, predetermined gap. A ball 315 is incorporated into the abutting member 311. The ball 315 is a steel ball, a ceramic ball, or the like, and is more precise than a typical resin-molded part, so the tolerance of the ball 315 can be ignored. Furthermore, in the X8 direction, the power transmission member 310 and the ball 315 incorporated into the abutting member 311 abut against each other, reducing the cumulative tolerance between the tooth position of the full-circumferential teeth portion 310d and the position of the opposing teeth portion 311h. Furthermore, because the abutting member 311 is rotatably engaged with the connecting member 309 around the X10 axis, it can move only in a direction parallel to the X10 axis and is unlikely to tilt relative to the X10 axis. Therefore, the thread portion of the lead screw 308 and the opposing teeth portion 311h can be separated with a precise, predetermined gap in the X8 direction. Even when tolerance accumulation in the direction orthogonal to the X8 direction is taken into consideration, the opposing tooth portion 311h can be spaced apart from the lead screw 308 with a predetermined gap with high precision.

[0066] Next, we will explain the effect of incorporating balls 315 into contact member 311. By using a high-strength component such as a metal or ceramic ball for ball 315, it is possible to obtain effects such as reducing wear and the like caused by the sliding and rotation of power transmission member 310 and reducing the coefficient of friction with power transmission member 310.

[0067] With the above configuration, the resistance force acting between the lead screw 308 and the power transmission member 310 can be reduced by, for example, the ratio of the diameter D8 to the diameter D7 shown in FIG. 11( b). This reduces the loss that occurs when transmitting force from the lead screw 308 to the power transmission member 310. As a result, the output of the driving force, etc., of the lens holding frame 303 can be increased relative to the torque input transmitted from the power source 306 to the lead screw 308, making it possible to provide an optical device 300 with improved driving efficiency. Furthermore, because there is no need to use a rolling configuration such as a bearing, it is possible to obtain a compact optical device 300 with low vibration noise and driving noise.

[0068] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist of the present invention.

Claims

1. An optical device comprising: a holding member movable in the optical axis direction of a lens; a lead screw extending in the optical axis direction and rotated by an actuator; a power transmission member having an engagement portion that engages with the lead screw and transmits power in the optical axis direction in response to rotation of the lead screw; a connecting member connected to the holding member and having a support portion that rotatably supports the power transmission member; an abutment member that abuts against the power transmission member; first biasing means that biases the abutment member from the holding member to the power transmission member in the optical axis direction; and second biasing means that biases the power transmission member to the lead screw, wherein in the optical axis direction, the power transmission member is biased against the connecting member by the abutment member, and in the optical axis direction, the connecting member is biased against the holding member by the power transmission member.

2. The optical device according to claim 1, wherein the power transmission member is sandwiched between the contact member and the connecting member in the optical axis direction.

3. An optical device as described in claim 1 or 2, characterized in that the rotational resistance torque acting on the support portion when the power transmission member rotates is smaller than the rotational resistance torque acting on the engagement portion when the lead screw rotates.

4. An optical device according to any one of claims 1 to 3, characterized in that the connecting member abuts against a surface that contains the rotation axis of the power transmission member in the optical axis direction.

5. An optical device according to any one of claims 1 to 4, characterized in that the abutment member abuts against a surface that contains the rotation axis of the power transmission member in the optical axis direction.

6. The optical device according to any one of claims 1 to 5, wherein the support portion is one of a hole portion and a shaft portion.

7. An optical device according to any one of claims 1 to 6, characterized in that the following condition is satisfied: 1<D2 / D1<100, where D1 is the diameter of the support portion and D is the diameter of the power transmission member.

8. An optical device as described in any one of claims 1 to 7, further comprising a third biasing means for biasing the abutment member against the connecting member in a direction perpendicular to the optical axis, the abutment member rotatably engaging with the connecting member, the abutment member having a first abutment portion abutting the power transmission member, a second abutment portion regulating relative rotation with the connecting member in the direction perpendicular to the optical axis, and a third abutment portion facing the power transmission member across the lead screw in the direction perpendicular to the optical axis, the third abutment portion being spaced from the lead screw by a gap smaller than the engagement height of the engagement portion in the direction perpendicular to the optical axis.

9. An optical device as described in claim 8, characterized in that in a first state in which a force equal to or greater than a predetermined value is not being applied to the optical device, the power transmission member abuts against the lead screw, and in a second state in which a force equal to or greater than the predetermined value is being applied to the optical device, the power transmission member and the abutment member abut against the lead screw.

10. An optical device as described in claim 9, characterized in that in the second state, the force with which the power transmission member and the abutment member are urged by the third urging means to the lead screw is greater than the force with which the power transmission member is urged by the second urging means to the lead screw in the first state.

11. The optical device according to any one of claims 8 to 10, characterized in that the third abutment portion is provided with teeth that are engageable with the thread portion of the lead screw.

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