Lens barrel and imaging apparatus

Abstract

To achieve miniaturization of a lens barrel and improvement in focusing accuracy.SOLUTION: A lens barrel comprises: a first lens group movable in an optical axis direction; a second lens group adjacent to the first lens group and having a movement range overlapping with that of the first lens group; first and second holding members for holding the first and second lens groups; driving means for moving the first holding member; first and second intermediate members that move by the driving means and transmit driving force to the first holding member; a first biasing member that biases the first intermediate member toward the driving means and biases the second intermediate member toward the first holding member; a second biasing member that biases the first holding member toward the second intermediate member; a guide shaft member that movably holds the second intermediate member and the first holding member; and a detection unit and a detected unit for detecting the position of the second intermediate member. The second biasing member allows the first holding member to retract relative to the second intermediate member in a direction opposite to the side of the second holding member. One of the detection unit and the detected unit is disposed on the second intermediate member.SELECTED DRAWING: Figure 11

Description

Technical Field

[0001] The present invention relates to a lens barrel, and more particularly to a lens barrel having a lens group that moves manually or by external driving means and a lens group that moves using electrical driving means, and an imaging device including the lens barrel.

Background Art

[0002] In order to shorten the shortest overall length of a zoom lens barrel, a technique is known that enables a configuration in which a second lens group that moves manually or by external driving means enters the moving range of a first lens group that moves using electrical driving means. In Patent Document 1, there are provided a first lens group that moves manually in the optical axis direction, a first holding member that holds the first lens group, a second lens group that is moved from the driving force of a driving means via an intermediate member, and a second holding member. When the first holding member interferes with the second holding member, a lens barrel structure is disclosed in which an urging member is displaced to absorb the impact between the lens groups. Also, a control method is disclosed in which the control of the driving means is changed according to the amount of interference in order to improve the driving accuracy and the imaging quality. In Patent Document 2, in order to enable origin detection even in an interference state, a configuration is disclosed in which an intermediate member is made into two bodies and a detected portion is arranged on a second intermediate member.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the prior art disclosed in the above-mentioned Patent Document 1, since one biasing member biases in the direction orthogonal to the optical axis and in the optical axis direction, if the biasing member is greatly crushed during interference, the biasing force in the direction orthogonal to the optical axis will be affected and stable biasing cannot be achieved. Further, since the biasing member is crushed while being offset from the guide shaft of the intermediate member, wear, abnormal noise, deformation, and snag may occur when overcoming the diameter difference between the intermediate member and the guide shaft. Further, since the detected portion is arranged via several components with respect to the guide bar that guides the second holding member, the error between the detection portion and the detected portion becomes large and the focus detection accuracy may deteriorate.

[0005] In the prior art disclosed in the above-mentioned Patent Document 2, since a detection means that cannot perform feedback control is used, it is difficult to drive the focus with high precision. If an absolute value sensor capable of feedback control is used to drive the focus with high precision, the space of the detected portion becomes large and the product may be enlarged.

[0006] Therefore, an object of the present invention is to provide a lens barrel that is advantageous in terms of, for example, miniaturization of a product and improvement of focus accuracy.

[0007] In order to solve the above problems, the present invention provides a first lens group movable in the optical axis direction, which is a direction along the optical axis; a second lens group adjacent to the first lens group in the optical axis direction and movable in the optical axis direction, the movement range of which overlaps with the movement range of the first lens group by a predetermined amount; a first holding member for holding the first lens group; a second holding member for holding the second lens group; driving means for moving the first holding member in the optical axis direction; a first intermediate member and a second intermediate member that move by the driving force of the driving means and transmit the driving force to the first holding member; a first biasing member for biasing the first intermediate member against the driving means and biasing the second intermediate member against the first holding member; a second biasing member for biasing the first holding member in the optical axis direction with respect to the second intermediate member; a guide shaft member for movably holding the second intermediate member and the first holding member and guiding the movement; and a detection unit and a detected unit for detecting the position of the second intermediate member in the optical axis direction. The second biasing member enables the first holding member to be retracted by at least the predetermined amount in a direction opposite to the side where the second holding member is disposed with respect to the second intermediate member, and either the detection unit or the detected unit is disposed on the second intermediate member.

Effect of the Invention

[0008] According to the present invention, for example, a lens barrel advantageous in terms of miniaturization of a product and improvement of focus accuracy can be provided.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Mode for Carrying Out the Invention

[0010] Hereinafter, preferred embodiments of the present invention will be described in detail based on the accompanying drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations are omitted.

[0011] <First Embodiment> Hereinafter, the lens barrel 100 according to the first embodiment will be described. FIG. 1 is a cross-sectional view of the lens barrel 100 according to the first embodiment. The line indicated by X-X in the figure represents the optical axis.

[0012] The mount 101 is a component fixed to the camera body 200 (shown in FIG. 15). The guide cylinder 102 is integrally fixed to the mount 101 together with the fixed cylinder 103. A cam ring 104 is rotatably held around the optical axis on the outer periphery of the guide cylinder 102. The cam ring 104 is connected to a zoom ring 105 rotatably held on the outer periphery of the fixed cylinder 103 by a key member (not shown), and is configured to rotate integrally by operating the zoom ring 105 from the outside.

[0013] The zoom sensor 106 as the focal length detection means is attached to the fixed cylinder 103 and is a sensor that electrically detects the rotation angle of the zoom ring 105. The zoom sensor 106 is electrically connected to a control board 107 disposed near the mount 101, and transmits focal length information during zooming to the control circuit. The control board 107 is electrically connected to a contact block 108 and receives communication with the camera body 200 and power supply.

[0014] The first lens group L1 is fixed to the first lens barrel 111, and the first lens barrel 111 is fixed to the straight cylinder 112.

[0015] The second lens group L2 is held by the second lens barrel 113, and the second lens barrel 113 is held by a shift unit 114 so as to be movable in a plane orthogonal to the optical axis. The shift unit 114 includes an actuator for driving the second lens barrel 113, a sensor for detecting the driving amount, and the like. The shift unit 114 is fixed to the guide cylinder 102 and is electrically connected to the control board 107. The control board 107 drives and controls the second lens barrel 113 to correct shake based on the shake signal detected by a bresensor 116 (acceleration sensor) attached to the fixed cylinder 103.

[0016] The third lens group L3 is held by the 3A lens barrel 117 and the 3B lens barrel 118, and both are fixed to the third group base lens barrel 120. The third group base lens barrel 120 holds an electromagnetic diaphragm unit 121, and the electromagnetic diaphragm unit 121 is electrically connected to the control board 107.

[0017] The fourth lens group L4 as the first lens group is held by the four-group lens barrel 122 as the first holding member, and the four-group lens barrel 122 is held by guide bars 123 (123a, 123b) described later on the three-group base lens barrel 120 so as to be movable in the direction along the optical axis (optical axis direction). The fourth lens group L4 is a lens for focus adjustment and is movable in the optical axis direction. Specifically, the fourth lens group L4 is driven in the optical axis direction by a linear ultrasonic motor 124 as driving means held by the three-group base lens barrel 120 to change the combined focal length.

[0018] The linear ultrasonic motor 124 includes a fixed part 125 and a movable part 126, vibrates a piezoelectric element ultrasonically, and drives the movable part 126 in the optical axis direction, which is based on a well-known technique. The piezoelectric element is electrically connected to the control board 107 by a flexible printed board (not shown).

[0019] The fifth lens group L5 as the second lens group is held by the five-group lens barrel 127 as the second holding member. The fifth lens group L5 is adjacent to the fourth lens group L4 in the optical axis direction and is arranged on the image plane side of the fourth lens group L4.

[0020] The first lens group L1, the third lens group L3, and the fifth lens group L5 are lenses that move in the optical axis direction during zooming, and cam followers (not shown) are provided on the straight tube 112, the three-group base lens barrel 120, and the five-group lens barrel 127. Each cam follower engages with a straight groove provided on the guide tube 102 and a cam groove provided on the cam ring 104. By rotating the cam ring 104, the first lens group L1, the third lens group L3, and the fifth lens group L5 are each configured to be able to move straight in the optical axis direction.

[0021] Also, since the fourth lens group L4 for focus adjustment is held by the three-group base lens barrel 120, it is driven in the optical axis direction by the linear ultrasonic motor 124 while moving together with the three-group base lens barrel 120 during zooming.

[0022] FIG. 2 is a diagram showing the movement locus of each lens group during zooming. This figure shows the movement locus from the wide-angle end (wide) to the telephoto end (tele) with respect to the mount 101. Specifically, it shows that the first lens group L1, the third lens group L3, and the fifth lens group L5 move during zooming, while the second lens group L2 does not move during zooming. L4 infinity shows the movement locus of the fourth lens group L4 in the state of being focused at infinity, and L4 closest shows the movement locus in the state of being focused at a predetermined closest distance.

[0023] During zooming, position information of the fourth lens group L4 that focuses on each focus position from infinity to the closest distance at each focal length from the wide-angle end to the telephoto end is stored as data. Based on this information and the focal length information detected by the zoom sensor 106, the driving of the four-group lens barrel 122 is controlled by the linear ultrasonic motor 124 so as to follow the line shown in FIG. 2.

[0024] Next, the holding structure of the four-group lens barrel 122 will be described. FIG. 3 is an exploded perspective view showing the holding structure of the four-group lens barrel 122. FIG. 4 is a perspective view showing the holding structure in a state where a rack 131 is assembled to the four-group lens barrel 122. In FIGS. 3 and 4, the guide bar 123a and the guide bar 123b are fixed to the three-group base lens barrel 120 at both ends, respectively. The guide bar 123a is a guide shaft member, which is inserted into a sleeve hole 122d as a first holding member guide portion and a sleeve hole 122e as a second holding member guide portion provided in the four-group lens barrel 122, and holds the four-group lens barrel 122 movably in the optical axis direction. The guide bar 123b is engaged with the U-shaped groove 122f of the four-group lens barrel 122, preventing the four-group lens barrel 122 from rotating around the guide bar 123a.

[0025] In this embodiment, the rack 131 (the first intermediate member) and the rack holder 132 (the second intermediate member) are each configured as an intermediate member.

[0026] The rack holder 132 has sleeve holes 132a and 132b as intermediate member guides. The rack holder 132 is movably held in the optical axis direction by the guide bar 123a when the guide bar 123a is inserted through the sleeve hole 132a and the sleeve hole 132b. A contact portion (not shown) contacts the four-group lens barrel 122 to prevent the rack holder 132 from rotating around the sleeve hole. The compression coil spring 134 as the second biasing member is an elastic member disposed in the space between the four-group lens barrel 122 and the rack holder 132 in the optical axis direction, and the guide bar 123a is inserted into the spiral coil portion. One end of the compression coil spring 134 biases the four-group lens barrel 122 toward the imaging surface side in the optical axis direction, and similarly, the other end biases the rack holder 132 toward the sleeve hole 122e of the four-group lens barrel 122. That is, the compression coil spring 134 biases the four-group lens barrel 122 toward the imaging surface side along the optical axis with respect to the rack holder 132. Therefore, when the rack holder 132 moves in the optical axis direction, the four-group lens barrel 122 moves in the same direction as the rack holder 132 integrally (interlockingly) with the rack holder 132. Note that the second biasing member only needs to be able to bias the four-group lens barrel 122 in the direction along the optical axis with respect to the rack holder 132, and a tension coil spring or a magnet may be used instead of the compression coil spring 134.

[0027] The rack 131 has a V-groove portion 131d at its tip engaging with a protrusion (not shown) provided on the movable part 126 of the linear ultrasonic motor 124, and the rotating shaft portion 131a engages with the sleeve hole 132c of the rack holder 132. The rack spring 133 as the first biasing member is disposed in the space between the rack 131 and the rack holder 132, and the rotating shaft portion 131a is inserted into the spiral coil portion. One end of the rack spring 133 biases the rack holder 132 toward the imaging surface side in the optical axis direction, and similarly the other end biases the rack 131 into the sleeve hole 132d of the rack holder 132. Therefore, when the rack 131 moves in the optical axis direction, the rack holder 132 moves integrally (in conjunction) with the rack 131 in the same direction as the rack 131. Also, one end of the arm portion of the rack spring 133 abuts against the rack 131 to bias the rack 131 toward the movable part 126 of the linear ultrasonic motor 124, and similarly the other end abuts against the rack holder 132 to bias the rack holder 132 toward the four-group lens barrel 122. Therefore, even if there are variations in component accuracy, it is possible to transmit the driving force of the linear ultrasonic motor 124 to the four-group lens barrel 122 without play due to the biasing force.

[0028] As described above, by integrating the intermediate members and integrating the biasing members, it is possible to stably bias in the direction orthogonal to the optical axis even during interference. Also, since there is no diameter difference and no offset in the portion where the compression coil spring 134 is inserted, wear, abnormal noise, deformation, and jamming do not occur.

[0029] Next, a method for driving the focus lens according to this embodiment will be described. FIG. 5 is a diagram showing the movement trajectories of the fourth lens group L4 and the fifth lens group L5. In this figure, with the third lens group L3 at a predetermined position as a reference, the movement trajectories of the fourth lens group L4 and the fifth lens group L5 from the wide-angle end to the telephoto end are shown. Similar to FIG. 2, L4 infinity indicates the movement trajectory of the fourth lens group L4 in a state where the focus is adjusted to infinity, and L4 closest indicates the movement trajectory in a state where the focus is adjusted to a predetermined closest distance. In this specification, a state where the focus is adjusted to a predetermined closest distance may be simply referred to as the closest. The intervals in the optical axis direction of each line indicate the clearances of each lens group. Therefore, when the lines intersect, it indicates that the lens barrels holding the lens groups interfere with each other.

[0030] The four-group lens barrel 122 that holds the fourth lens group L4, which is a focus lens, is driven and controlled by the linear ultrasonic motor 124 so as to follow the line indicated by L4 infinity in a state where the focus is adjusted to infinity by zooming. On the other hand, in a state where the focus is adjusted to a predetermined closest distance, the four-group lens barrel 122 is driven and controlled by the linear ultrasonic motor 124 so as to follow the line indicated by L4 closest. Note that the position information of the fourth lens group L4 that focuses on each focus position from infinity to the closest is stored as data. Based on this information and the focal length information detected by the zoom sensor 106, the driving of the four-group lens barrel 122 is controlled by the linear ultrasonic motor 124 so as to follow the line shown in FIG. 5.

[0031] The four-group lens barrel 122 that holds the fourth lens group L4, which is a focus lens, is driven and controlled electrically according to zooming, but zooming is performed manually or by external driving means. Therefore, when zooming at high speed, there is a limit to the driving speed of the focus lens, so it may not be possible to keep up with zooming. In the case of zooming with a built-in motor that has existed conventionally, the above problem does not occur by appropriately controlling the speed of the built-in motor.

[0032] In the lens barrel 100 of the present embodiment, when moving each lens group from the telephoto end to the wide-angle end at high speed with the focus adjusted to the closest distance, the driving of the four-group lens barrel 122 may not be in time, and there is a possibility that the four-group lens barrel 122 and the five-group lens barrel 127 may interfere with each other. That is, in the present embodiment, the moving range of the fourth lens group L4 and the fifth lens group L5 overlap by a predetermined amount. In FIG. 5, the range where interference may occur is shown as an interference region. The maximum amount of interference is the amount of overlap in the optical axis direction between the position of the wide-angle end (wide) of the movement locus (the line indicated by L5) of the fifth lens group L5 held by the five-group lens barrel 127 and the position at the telephoto end closest to L4, which is the amount indicated by A in this figure.

[0033] This amount of interference depends on the zooming speed and the speed of the actuator of the focus lens in the normal shooting state. Assume that the lens barrel 100 of the present embodiment is applied to an interchangeable lens, and the lens barrel 100 is removed from the camera body 200 with the fourth lens group L4, which is the focus lens, in a state closest to the telephoto end. In this case, since the power is cut off, the fourth lens group L4, which is the focus lens, cannot be driven. Therefore, when the fifth lens group L5 is moved to the position of the wide-angle end, it will interfere by the amount A shown in FIG. 5 as it is.

[0034] Next, the movement when the four-group lens barrel 122 holding the fourth lens group L4, which is the focus lens, interferes with the five-group lens barrel 127 holding the fifth lens group L5 will be described. FIG. 6 is a cross-sectional view showing a state (normal state) where the four-group lens barrel 122 and the five-group lens barrel 127 do not interfere. FIG. 7 is a cross-sectional view showing a state (interference state) where the four-group lens barrel 122 and the five-group lens barrel 127 interfere.

[0035] When zooming in at high speed from the telephoto end, or when zooming toward the wide-angle end with the fourth lens group L4 in the closest state to the telephoto end and the power turned off as described above, the contact portion 122g of the four-group lens barrel 122 contacts the contact portion 127a provided on the five-group lens barrel 127 as shown in FIG. 7. As a result, the four-group lens barrel 122 is pushed in the optical axis direction by the five-group lens barrel 127 and moves toward the subject side (the direction opposite to the side where the five-group lens barrel 127 is arranged). Then, since the integrated rack 131 and the rack holder 132 are held by the movable portion 126 of the linear ultrasonic motor 124 and the movable portion 126 is stationary due to the frictional force with the fixed portion 125, the compression coil spring 134 is compressed. Then, the rack holder 132 and the four-group lens barrel 122 are separated in the optical axis direction, and the four-group lens barrel 122 moves in the direction together with the five-group lens barrel 127 (hereinafter, this state is referred to as retraction or a retracted state). Therefore, even if interference occurs, damage to the lens barrel, the rack, or the motor can be prevented.

[0036] In a conventional lens barrel, optical design was performed so that no other lenses were arranged within the driving range of a focus lens driven electrically. In other words, a clearance was provided with other lens groups so as not to interfere with the moving range of the focus lens at the telephoto end, and the same amount of clearance was opened at the wide-angle end as well. Since the moving amount of the focus lens at the wide-angle end is often smaller than that at the telephoto end, there are often unnecessary clearances at the wide-angle end, and the overall length of the lens has increased accordingly.

[0037] In the lens barrel 100 according to the present embodiment, by adopting a configuration in which the rack holder 132 and the four-group lens barrel 122 can be separated in the optical axis direction, a configuration is adopted that allows interference of the focus lens when zooming at high speed. As a result, the unnecessary clearance between the lens groups can be made smaller, preferably minimized, and the entire lens barrel (the length in the optical axis direction) can be made more compact.

[0038] Next, the configuration of the focus unit 3 will be described. FIG. 8 is a perspective view showing a normal state of a part of the focus unit 3. FIG. 9 is a cross-sectional view showing the normal state of the four-group lens barrel 122 and the rack holder 132. FIG. 10 is a cross-sectional view showing the interference state of the four-group lens barrel 122 and the rack holder 132.

[0039] The focus unit 3 includes a three-group base lens barrel 120, a linear ultrasonic motor 124, a position sensor 136, a 3A-group lens barrel 117 (shown in FIG. 1), a 3B-group lens barrel 118 (shown in FIG. 1), and a four-group lens barrel 122, etc. Since the holding of the 3A-group lens barrel 117, the 3B-group lens barrel 118, and the four-group lens barrel 122 with respect to the three-group base lens barrel 120 has been described above, it will be omitted.

[0040] For the linear ultrasonic motor 124, the fixed part 125 is fixed to the three-group base lens barrel 120 with screws. The scale 135 is a component in which a continuous pattern is formed in the optical axis direction. The scale 135 is adhesively fixed to the rack holder 132. The position sensor 136 detects the relative positional relationship between the position sensor 136 and the scale 135 by reading the scale 135. Specifically, by reading the pattern of the scale 135 with the position sensor 136 attached to the three-group base lens barrel 120 side, the relative position in the optical axis direction of the rack holder 132 with respect to the three-group base lens barrel 120 can be detected. That is, the scale 135 and the position sensor 136 are absolute value sensors capable of detecting absolute values. Here, as an example, an absolute value sensor of the optical pulse counting method is used, but an absolute value sensor of the magnetic type pulse counting method may also be used. By reading (scanning) the pattern of the scale 135 with the position sensor 136, the relative position of the rack holder 132 is detected. Therefore, the scale 135 has a length in the optical axis direction that is equal to or greater than the distance (driving amount) between the position where the fourth lens group L4 is closest to the object side and the position where it is closest to the image side in the entire zoom range. In the case shown in FIG. 5, the fourth lens group L4 is located closest to the object side when at TELE infinity and closest to the image side when at TELE closest focus.

[0041] In the normal state where no interference occurs, the rack holder 132 and the four-group lens barrel 122 can move integrally. Therefore, in the normal state, the relative position of the four-group lens barrel 122 in the optical axis direction with respect to the three-group base lens barrel 120 can also be detected by the position sensor 136. On the other hand, in the interference state, the relative positions of the rack holder 132 and the four-group lens barrel 122 are different from those in the normal state. That is, in the interference state, the relationship between the relative positions of the rack holder 132 and the three-group base lens barrel 120 detected by the position sensor 136 and the scale 135 and the relationship between the relative positions of the four-group lens barrel 122 and the three-group base lens barrel 120 are different.

[0042] As described above, since the position of the rack holder 132 to which the scale 135 is fixed is determined by the guide bar 123a fixed to the three-group base lens barrel 120, the error between the position sensor 136 and the scale 135 can be reduced. Since the detection accuracy is sensitive to the deviation of the distance between the position sensor 136 and the scale 135, although the number of parts increases by integrating two intermediate members, the deterioration of the focus detection accuracy can be suppressed.

[0043] Next, a control method for the linear ultrasonic motor 124 will be described. Conventionally, it has been common to perform feedback control in which the position of the four-group lens barrel 122 is detected by a scale provided on the four-group lens barrel 122, and control is performed based on the difference between the drive command position and the actual position. When a scale is provided on the four-group lens barrel 122, even if the linear ultrasonic motor 124 is driven in the interference state, the position of the four-group lens barrel 122 obtained from the scale will continue to not change, and a large deviation will occur in the feedback control. Also, if an attempt is made to drive with a large thrust to reduce the deviation, there are problems such as noise during collision, noise during driving, and control-induced oscillation.

[0044] As described above, in the normal state where no interference occurs in the present embodiment, since the rack holder 132 to which the scale 135 is fixed and the four-group lens barrel 122 move integrally, feedback control as in the prior art is performed based on the output result of the position sensor 136. On the other hand, even in the interference state, when the linear ultrasonic motor 124 is driven, since the rack holder 132 is held by the movable part 126, the position of the rack holder 132 obtained from the scale 135 changes. At this time, since the four-group lens barrel 122 moves integrally with the five-group lens barrel 127, the position of the five-group lens barrel 127 can be known from the detection result of the zoom sensor 106, and the position of the four-group lens barrel 122 can also be known. In this way, the positions of the rack holder 132 and the four-group lens barrel 122 can be known even in the interference state. As a result, the interference amount can be calculated from the difference in the positions of the rack holder 132 and the four-group lens barrel 122.

[0045] As described above, by arranging the scale 135 on the rack holder 132, feedback control can be performed even in the interference state. Further, by changing the driving speed, acceleration, etc. according to the interference amount, it is possible to quickly return to the normal state while suppressing deterioration in quality such as position accuracy and driving noise. Furthermore, the position deviation does not become large during drive control, and oscillation due to the position deviation does not occur.

[0046] Next, the arrangement of the scale 135 in the optical axis direction, which is the main part of the present invention, will be described. FIG. 15 is a diagram for explaining the increase in size due to the arrangement of the scale 135 in the optical axis direction. FIG. 15(A) shows the normal state, and FIG. 15(B) shows the interference state. Further, FIG. 11 is a diagram for explaining the miniaturization due to the arrangement of the scale 135 in the optical axis direction according to the first embodiment. FIG. 11(A) shows the normal state according to the present embodiment, and FIG. 11(B) shows the interference state according to the present embodiment.

[0047] As shown in FIG. 15(A), consider a case where a scale holding portion 132e that holds a scale 135 of a rack holder 132 is arranged such that, in a normal state, the center in the optical axis direction of the scale 135, the center between the sleeve holes 132a and 132b, are at the same position (overlapping position) in the optical axis direction. In this case, as shown in FIG. 15(A), in the normal state, the scale holding portion 132e protrudes beyond the sleeve hole 122e of the four-group lens barrel 122 toward the subject side. With such an arrangement, it is necessary to avoid interference with the 3B-group lens barrel 118 on the subject side by the amount that the scale holding portion 132e protrudes toward the subject side. If an attempt is made to avoid it by making a notch in the radial direction, the design freedom deteriorates. Also, if it cannot be avoided by making a notch, it is necessary to create a space in the optical axis direction, which causes the lens barrel to become larger in the optical axis direction. The larger the amount by which the scale holding portion 132e protrudes toward the subject side, the larger the amount of increase in size.

[0048] On the other hand, in FIG. 11 showing the configuration according to the present embodiment, as shown in FIG. 11(A), in the normal state, the end portion (the surface on the subject side) of the scale holding portion 132e is arranged to overlap with the sleeve hole 122e of the four-group lens barrel 122 in the optical axis direction. In other words, in the normal state, the center of the scale 135 in the optical axis direction is arranged closer to the five-group lens barrel 127 side (image plane side) than the center between the sleeve holes 132a and 132b. By arranging it in this way, the space on the subject side of the four-group lens barrel 122 and the rack holder 132 is determined by the position in the optical axis direction of the sleeve hole 122e of the four-group lens barrel 122. Therefore, it becomes unnecessary to avoid the 3B-group lens barrel 118 on the subject side.

[0049] Also, as shown in Fig. 11(B), it is preferable that the rack holder 132 is arranged such that in the interference state, a part of the rack holder 132 overlaps with the sleeve hole 122d in the optical axis direction. By arranging it in such a way, even during interference, the scale 135 remains within the range of the space that the four-group lens barrel 122 used in the normal state, so there is no need to avoid the five-group lens barrel 127 on the imaging surface side, or the amount to be avoided is reduced. If the rack holder 132 protrudes greatly toward the five-group lens barrel 127 side in the interference state, it is necessary to avoid the five-group lens barrel 127. For this reason, it is more preferable that the rack holder 132 is arranged at a position that does not protrude toward the image surface side (the five-group lens barrel 127 side) than the four-group lens barrel 122 in the interference state.

[0050] As described above, by arranging the object side surface of the scale holding portion 132e to overlap with the sleeve hole 122e of the four-group lens barrel 122, the space in the optical axis direction between the four-group lens barrel 122 and the rack holder 132 can be reduced. As a result, the lens barrel can be miniaturized in the optical axis direction.

[0051] Here, even if the scale holding portion 132e is arranged at a position protruding toward the object side from the sleeve hole 122e, the same effect can be obtained if the center of the scale 135 is arranged on the imaging surface side rather than the center between the sleeve hole 132a and the sleeve hole 132b in the normal state. Also, the scale holding portion 132e may be arranged such that the object side surface is on the imaging surface side rather than the sleeve hole 122e in the normal state. Further, the scale 135 may be arranged on the three-group base lens barrel 120, and the position sensor 136 may be arranged on the rack holder 132.

[0052] FIG. 12 is a diagram for explaining the relationship between the sleeve holes 132a and 132b and the guide bar 123a. This figure shows a view in a plane orthogonal to the optical axes of the sleeve hole 132b and the guide bar 123a. The sleeve hole 132b preferably has two surfaces 132f so as to contact the guide bar 123a at two contact points 132g on its inner circumference. The sleeve hole 132a preferably has a similar configuration. By having such a configuration, even if the posture of the lens barrel changes, the positions of the rack holder 132 and the guide bar 123a can be prevented from changing, so that deterioration of focus accuracy due to fluctuations in posture can be suppressed.

[0053] The retracting range in this embodiment corresponds to the range A in FIG. 5 and exists on the imaging surface side in the optical axis direction, but it may be on the subject side or may exist on both sides.

[0054] In this embodiment, an ultrasonic motor is employed to drive the four-group lens barrel 122, but the same effect can be achieved by employing a driving means such as a stepping motor.

[0055] <Second Embodiment> Hereinafter, only the differences from the first embodiment will be described for the lens barrel 100 according to the second embodiment of the present invention. FIG. 13 is a diagram showing the arrangement of the scale holding portion 132e in the direction orthogonal to the optical axis in the second embodiment. This figure shows the four-group lens barrel 122 in a plane orthogonal to the optical axis. As shown in FIG. 13, in the second embodiment, the arrangement of the scale holding portion 132e in the direction orthogonal to the optical axis is different from that in the first embodiment.

[0056] In this embodiment, the detection surface of the position sensor 136 is arranged substantially perpendicular to the line 141 connecting the center of the guide bar 123a and the center of the position sensor 136 in the direction orthogonal to the optical axis. By arranging it in this way, when the rack holder 132 rotates around the guide bar 123a, the change in the distance between the position sensor 136 and the scale 135 can be reduced, so that the focus detection accuracy can be improved.

[0057] Also, the scale 135 is arranged in the direction orthogonal to the optical axis on the extension line of the line 140 connecting the optical axis center O and the center of the guide bar 123a. With this arrangement, the circumferential space occupied by the rack holder 132 can be reduced. Here, the scale 135 may be arranged on the side of the linear ultrasonic motor 124 rather than on the extension line of the line 140 connecting the optical axis center O and the center of the guide bar 123a. In FIG. 13, the line 140 and the line 141 are shown overlapping, but there may be a case where the line 140 and the line 141 do not overlap.

[0058] Also, a scale holding portion 132e is arranged between the position sensor 136 and the guide bar 123a in the direction orthogonal to the optical axis. With this arrangement, when the position sensor 136 is of the light-emitting type, it is possible to prevent the occurrence of ghosts due to reflection on the guide bar 123a.

[0059] <Embodiment of the imaging device> FIG. 14 is a diagram showing a configuration example of the imaging device 300. An imaging device that enjoys the effects of the present invention can be realized by the imaging device 300 having the lens barrel 100 of the above-described embodiment and the camera body 200 that holds the imaging element 210 that receives light from the lens barrel 100.

[0060] <Other embodiments> As described above, the preferred embodiments of the present invention have been described. However, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist thereof.

[0061] In the above-described embodiment, the lens barrel as an interchangeable lens for taking still images and moving images has been described. However, in the lens barrel for recording images, the same effect can be obtained when performing manual zooming. Further, it is applicable not only to the focus lens in the lens barrel but also to other lenses that move during zooming and to cases where the lens barrel is downsized by contact with a fixed portion.

[0062] The disclosure of this embodiment includes the following configurations. (Configuration 1) A first lens group movable in the optical axis direction, which is a direction along the optical axis; A second lens group adjacent to the first lens group in the optical axis direction, movable in the optical axis direction, and having a movement range that overlaps with the movement range of the first lens group by a predetermined amount; A first holding member that holds the first lens group; A second holding member that holds the second lens group; Drive means for moving the first holding member in the optical axis direction; A first intermediate member and a second intermediate member that move by the driving force of the drive means and transmit the driving force to the first holding member; A first biasing member that biases the first intermediate member against the drive means and biases the second intermediate member against the first holding member; A second biasing member that biases the first holding member in the optical axis direction with respect to the second intermediate member; A guide shaft member that movably holds the second intermediate member and the first holding member and guides the movement; A detection unit and a detected unit that detect the position of the second intermediate member in the optical axis direction, and having; The second biasing member can retract the first holding member by at least the predetermined amount in a direction opposite to the side where the second holding member is disposed with respect to the second intermediate member; A lens barrel, wherein either one of the detection unit and the detected unit is disposed on the second intermediate member.

[0063] (Configuration 2) The second intermediate member has two intermediate member guide portions through which the guide shaft member is inserted; In the optical axis direction, the center of the detected unit in the optical axis direction is disposed closer to the second holding member side than the center of the two intermediate member guide portions in the optical axis direction. The lens barrel according to Configuration 1, characterized in that.

[0064] (Configuration 3) The intermediate member guide part abuts against the guide shaft member at two contact points, and the lens barrel according to Configuration 2, characterized in that.

[0065] (Configuration 4) The first holding member has a first holding member guide part and a second holding member guide part through which the guide shaft member is inserted. The first holding member guide part is disposed closer to the second holding member side than the second holding member guide part. When the first holding member is retracted from the second intermediate member by the predetermined amount, the second intermediate member and the first holding member guide part overlap in the optical axis direction, and the lens barrel according to any one of Configurations 1 to 3, characterized in that.

[0066] (Configuration 5) When the first holding member is not retracted from the second intermediate member, the end of the second intermediate member on the side opposite to the second holding member overlaps with the second holding member guide part in the optical axis direction or is disposed closer to the second holding member side than the second holding member guide part, and the lens barrel according to Configuration 4, characterized in that.

[0067] (Configuration 6) The detection part reads the detected part to detect the relative positional relationship between the detection part and the detected part. The detected part has a length equal to or greater than the driving amount of the first lens group in the optical axis direction, and the lens barrel according to any one of Configurations 1 to 5, characterized in that.

[0068] (Configuration 7) The detection surface of the detection part is disposed substantially perpendicular to the line connecting the center of the guide shaft member and the center of the detection part in a plane orthogonal to the optical axis, and the lens barrel according to any one of Configurations 1 to 6, characterized in that.

[0069] (Configuration 8) The detected part is arranged on the extension line of the line connecting the optical axis and the center of the guide shaft member in a plane orthogonal to the optical axis, or on the driving means side from the extension line, and is characterized by the lens barrel according to any one of Configurations 1 to 7.

[0070] (Configuration 9) The second intermediate member is arranged between the detection part and the guide shaft member in a plane orthogonal to the optical axis, and is characterized by the lens barrel according to any one of Configurations 1 to 8.

[0071] (Configuration 10) It has a focal length detection means for detecting the focal length, From the detection results of the detection part and the focal length detection means, the relative position in the optical axis direction of the first holding member and the second intermediate member is calculated, and is characterized by the lens barrel according to any one of Configurations 1 to 9.

[0072] (Configuration 11) The second biasing member is an elastic member, and is characterized by the lens barrel according to any one of Configurations 1 to 10.

[0073] (Configuration 12) The detected part is arranged on the second intermediate member, and is characterized by the lens barrel according to any one of Configurations 1 to 11.

[0074] (Configuration 13) The first lens group is a lens group that moves during focus adjustment, The second lens group is a lens group that moves during zooming and is characterized by the lens barrel according to any one of Configurations 1 to 12.

[0075] (Configuration 14) An imaging device including the lens barrel according to any one of Configurations 1 to 13 and an imaging element that receives an image formed by the lens barrel.

Explanation of Signs

[0076] 100 Lens barrel 131 Rack 132 Rack holder 133 Rack spring 134 Compression coil spring 135 Scale 136 Position sensor 200 Camera body 300 Imaging device L4 Fourth lens group L5 Fifth lens group

Claims

1. a first lens group movable in the optical axis direction, which is the direction along the optical axis; a second lens group adjacent to the first lens group in the optical axis direction and movable in the optical axis direction, the movement range of which overlaps with the movement range of the first lens group by a predetermined amount; a first holding member for holding the first lens group; a second holding member for holding the second lens group; driving means for moving the first holding member in the optical axis direction; a first intermediate member and a second intermediate member that are moved by the driving force of the driving means and transmit the driving force to the first holding member; a first biasing member that biases the first intermediate member against the driving means and biases the second intermediate member against the first holding member; a second biasing member that biases the first holding member in the optical axis direction with respect to the second intermediate member; a guide shaft member that movably holds the second intermediate member and the first holding member and guides the movement; a detection unit and a detected unit for detecting the position of the second intermediate member in the optical axis direction; and the second biasing member enables the first holding member to be retracted by at least the predetermined amount in a direction opposite to the side where the second holding member is disposed with respect to the second intermediate member, A lens barrel, wherein either one of the detection unit and the detected unit is disposed on the second intermediate member.

2. The second intermediate member has two intermediate member guide portions through which the guide shaft member is inserted, The lens barrel according to claim 1, wherein, in the optical axis direction, the center of the detected unit in the optical axis direction is disposed closer to the second holding member side than the center in the optical axis direction between the two intermediate member guide portions.

3. The lens barrel according to claim 2, wherein the intermediate member guide portion abuts on the guide shaft member at two contact points.

4. The first holding member has a first holding member guide portion and a second holding member guide portion through which the guide shaft member is inserted, The first holding member guide portion is disposed closer to the second holding member side than the second holding member guide portion, The lens barrel according to claim 1, wherein when the first holding member is retracted by the predetermined amount with respect to the second intermediate member, the second intermediate member and the first holding member guide portion overlap in the optical axis direction.

5. When the first holding member has not retracted with respect to the second intermediate member, the end of the second intermediate member on the side opposite to the second holding member overlaps with the second holding member guide portion in the optical axis direction, or is disposed closer to the second holding member than the second holding member guide portion. The lens barrel according to claim 4, characterized in that.

6. The detection unit reads the detected unit to detect the relative positional relationship between the detection unit and the detected unit. The detected unit has a length equal to or greater than the driving amount of the first lens group in the optical axis direction. The lens barrel according to claim 1, characterized in that.

7. The detection surface of the detection unit is disposed substantially perpendicular to the line connecting the center of the guide shaft member and the center of the detection unit in a plane perpendicular to the optical axis. The lens barrel according to claim 1, characterized in that.

8. The detected unit is disposed on the extension line of the line connecting the optical axis and the center of the guide shaft member, or on the driving means side of the extension line, in a plane perpendicular to the optical axis. The lens barrel according to claim 1, characterized in that.

9. The second intermediate member is disposed between the detection unit and the guide shaft member in a plane perpendicular to the optical axis. The lens barrel according to claim 1, characterized in that.

10. Having a focal length detection means for detecting the focal length. Calculating the relative position in the optical axis direction between the first holding member and the second intermediate member from the detection results of the detection unit and the focal length detection means. The lens barrel according to claim 1, characterized in that.

11. The second biasing member is an elastic member. The lens barrel according to claim 1, characterized in that.

12. The detected unit is disposed on the second intermediate member. The lens barrel according to claim 1, characterized in that.

13. The first lens group is a lens group that moves during focus adjustment. The second lens group is a lens group that moves during zooming. The lens barrel according to claim 1, characterized in that.

14. An imaging device, comprising: the lens barrel according to any one of claims 1 to 13; and an imaging element that receives an image formed by the lens barrel.

Images