JP2007114810A - Zoom lens barrel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a zoom lens barrel with which movable ranges of respective lens groups can be sufficiently secured without enlarging a cam tube even if it is necessary to form a plurality of cam grooves on the same circumferential surface of the same cam. <P>SOLUTION: The zoom lens barrel performs zooming by moving the plurality of lens groups, which constitute a photo-taking optical system, in an optical direction. The zoom lens barrel includes a first lens group of the plurality of lens groups and a second lens group of the plurality of lens groups. The zoom lens barrel also includes the cam that has a first cam region for moving the first lens group in the direction of the optical axis and a second cam region for moving the second lens group in the direction of the optical axis. The cam commonly use overlapping partial regions of the first cam region and the second cam region in performing the zooming. The cam forms a zooming interval between the first lens group and the second lens group by the first cam region and the second cam region. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a zoom lens barrel, and more particularly to a zoom lens barrel that performs zooming by moving a plurality of lens groups constituting a photographing optical system in the optical axis direction.

  Conventionally, in a zoom lens barrel in which a plurality of lens groups including a focus lens group are moved in the optical axis direction to perform a zoom operation, cam grooves for driving different lens groups that advance and retreat independently are individually provided. It is formed independently according to the movement.

  In such a lens barrel, the focus lens group is extended with the infinite position as the reference position, and when focusing close, the focus lens group is extended from the infinite position toward the close position to perform focusing. .

  12A, 12B, and 12C show an example of a retractable zoom lens barrel in which the photographing lens is a zoom lens having three groups and the second lens group is a focus lens. FIG. 6 is an explanatory diagram showing the position of each lens group in the retracted, wide, and tele states.

  As shown in FIGS. 12B and 12C, the second lens group (focus lens group) 202 is connected to the first and third lens groups 201 and 203 in the wide and tele states of the zoom lens barrel. On the other hand, it is normally located at an infinite position indicated by a solid line in the figure. Then, focusing to the closest position is performed by extending the second lens group 202 from an infinite position toward the closest position on the first lens group side indicated by a two-dot chain line in the drawing. After the photographing is completed, the second lens group 202 is reset to the infinite reference position.

  Further, in order to store the zoom lens barrel in the retracted position after the photographing is finished, as shown in FIG. 12A, the second lens group 202 is located at the infinite reference position without moving, that is, While maintaining the reset state at the infinite reference position, the zooming of the first and third lens groups is performed while moving integrally between the first lens group 201 and the second lens group 202. The interval is shortened and the total length is shortened. Accordingly, in the retracted state, the lens is retracted leaving a space for the focus lens group that is brought out to the nearest position.

  By the way, in the conventional cam groove for moving the lens group, since a plurality of cam grooves are provided on the same peripheral surface of the same cam cylinder, it is difficult to sufficiently secure the movable range of each lens group.

  That is, when a plurality of different cam grooves are formed adjacent to each other, the rotation angle of the cam grooves is reduced, and the pressure angle applied to each cam groove is increased. In order to relieve the pressure angle, if the diameter of the cam barrel is increased to cope with it, the lens barrel is increased in size. If the cam grooves are not adjacent to each other and are shifted in the thrust direction so that the cam grooves do not overlap with each other, the entire length of the cam barrel increases, and in this case also, the lens barrel is enlarged.

  The present invention has been made in view of the above circumstances, and its purpose is to increase the size of the cam cylinder even when it is necessary to form a plurality of cam grooves on the same peripheral surface of the same cam. It is an object of the present invention to provide a zoom lens barrel capable of sufficiently securing the movable range of each lens group.

  In order to achieve the above object, a zoom lens barrel according to the present invention is a zoom lens barrel that performs zooming by moving a plurality of lens groups constituting an imaging optical system in the optical axis direction, respectively. A first lens group, a second lens group of the plurality of lens groups, a first cam region for moving the first lens group in the optical axis direction, and the second lens. A second cam region for moving the group in the optical axis direction, and when performing the zooming, a partial region of the first cam region and the second cam region is overlapped, and the overlap region is A cam that is used in common and that forms a zooming group between the first lens group and the second lens group by the first cam region and the second cam region. Features.

  According to the present invention, even when it is necessary to form a plurality of cam grooves on the same peripheral surface of the same cam, the movable range of each lens group can be sufficiently ensured without increasing the size of the cam cylinder. A zoom lens barrel that can be provided can be provided.

  The present invention will be described below with reference to the illustrated embodiments.

  FIGS. 1 to 8 relate to an embodiment of the present invention. FIG. 1 shows a zoom lens barrel according to the present invention in a tele state and cut at an angular position of 120 ° around the optical axis when viewed from the front. FIG. 2 is a cross-sectional view, FIG. 2 is a longitudinal sectional view of an essential part showing only the vicinity of a fitting portion between the first cam cylinder and the zoom cylinder of the zoom lens barrel in FIG. 1, and FIG. 3 is a zoom lens barrel in FIG. 4 is a cross-sectional view of the zoom lens barrel shown in FIG. 1 in a retracted state with the optical axis viewed from the front and centered on the optical axis. FIG. 5 is a developed view showing cam groove shapes of the movable barrel, the first cam barrel, and the second cam barrel in the tele state of the zoom lens barrel shown in FIG. 6 is a perspective view of the main part of the guide tube in the zoom lens barrel of FIG. 1, and FIG. Perspective view of a feed screw mechanism for focusing the lens barrel, FIG. 8 is a graph diagram for designing the rotation angle and the feed amount of each cylinder in the zoom lens barrel.

  As shown in FIGS. 1 to 4, the zoom lens according to the present embodiment includes a three-unit zoom lens including a first lens group 120, a second lens group 130, and a third lens group 140. The lens group moves integrally during zooming. These lens groups are held in a first group cylinder 70, a second group cylinder 90, and a third group cylinder 100, respectively. The lens group 130 is held by a second group cylinder 90 as a focus lens group. The second group cylinder 90 is further supported by a zoom cylinder 80, and focusing is performed by a known feed screw so that the zoom cylinder 80 and the second group cylinder 90 are extended. 90 is performed by relative movement.

  The zoom lens barrel is movable with respect to the camera barrel 160 as a reference barrel that can be moved back and forth between a retracted position, which is a retracted position, and a projecting projection position. A rotating cylinder 30 as an outer cylinder for zooming, a guide cylinder 40 that is rotationally driven by the rotating cylinder 30 and moved forward and backward by a cam of the movable cylinder 20, and a state that is not rotated by being guided by the movable cylinder 20 A first cam cylinder 50 that is driven forward and backward simultaneously with the guide cylinder 40, a second cam cylinder 60 whose rotational direction is guided by the guide cylinder 40 and driven forward and backward by the cam of the first cam cylinder 50, A zoom cylinder 80 guided by the first cam cylinder 50 and driven to advance and retract by the cam of the second cam cylinder 60, and guided by the first zoom cylinder 80 and driven to advance and retract by the cam of the second cam cylinder 60; First A first group cylinder 70 that supports the lens group 120, a second group cylinder 90 that supports the second lens group 130, and is supported by the zoom cylinder 80. The main part is constituted by the third group cylinder 100 that supports the three lens group 140.

  On the distal end side of the camera body 160, a protrusion 161 having the same diameter as that of the third group cylinder 100 is formed.

A moving plate 10 is fixed to the base end portion of the moving cylinder 20 with screws or the like. The moving plate 10 is pivotally supported by the camera main body 160 and is supported so as not to rotate but to advance and retreat in the optical axis direction. The movable plate 10 is provided with a known drive mechanism (not shown) having a setup motor. When the movable plate 10 is driven by the drive mechanism, the movable cylinder 20 is separated from the movable plate. The retractable position and the protruding position are integrally moved forward and backward. Further, the rotating cylinder 30 is rotatably fitted to the outer peripheral surface of the moving cylinder 20. A thrust receiving groove 32 is formed on the inner periphery on the tip side of the rotating cylinder 30, and a thrust receiving rib 22 formed outwardly at the tip of the movable cylinder 20 is formed in the thrust receiving groove 32. It is fitted and the relative movement of the rotating cylinder 30 relative to the fixed cylinder 20 in the thrust direction is restricted.

  A gear portion 35 for transmitting power from a zoom motor (not shown) to perform zooming is formed on the outer peripheral surface on the proximal end side of the rotary cylinder 30.

  Further, a thrust receiving groove 34 is formed adjacent to the distal end side of the gear portion 35 on the outer peripheral surface on the proximal end side of the rotary cylinder 30, and the thrust receiving groove 34 is formed on the camera body 160. A formed bayonet-type thrust receiver (not shown) is freely detachable, and is fitted in a bayonet-type manner by rotating the rotary cylinder 30. The bayonet-type thrust receiver is fitted when the zoom lens barrel is in the protruding position, and is detached when the zoom lens barrel is retracted.

  The guide cylinder 40 is fitted to the inner peripheral surface of the movable cylinder 20. As shown in FIG. 6, cam pins 41a, 42b, and 41c are formed on the outer periphery of the proximal end side of the guide tube 40 so as to protrude outward. These cam pins 41a, 41b, and 41c are fitted into three inclined cam grooves 21a and inclined cam grooves 21b and 21c (see FIG. 5) formed on the inner peripheral surface of the movable cylinder 20 at equal intervals. Has been. The cam grooves 21b and 21c are formed as bottomed cam grooves, and the cam groove hole 21a is formed as a through hole.

  Further, a rotation driving pin 43 is formed at the tip of the cam pin 41a (see FIG. 6). The rotation drive pin 43 protrudes from the cam groove hole 21a to the outer peripheral side of the movable cylinder 20, and is fitted into a rotation drive key groove 33 formed along the optical axis direction on the inner surface of the rotation cylinder 30. Has been. Therefore, when the rotary cylinder 30 is rotated, the guide cylinder 40 is rotated synchronously and is advanced and retracted in the optical axis direction along the cam groove hole 21a and the cam grooves 21b and 21c of the movable cylinder 20.

  The first cam cylinder 50 is fitted on the inner peripheral surface of the guide cylinder 40. On the base end side of the first cam cylinder 50, a guide key 53 is formed to project outward, and the guide key 53 is formed on the inner surface of the movable cylinder 20 along the optical axis direction. The first cam cylinder 50 is guided in a straight line by being fitted in the straight key groove 23 thus formed.

  A thrust receiving rib 52 is formed near the base end portion of the outer periphery of the first cam cylinder 50. The thrust receiving rib 52 is formed on the inner peripheral surface of the guide cylinder 40 on the base end side. The thrust receiving groove 42 is fitted in a bayonet manner, and the relative movement of the cam cylinder 50 in the thrust direction with respect to the guide cylinder 40 is restricted. Therefore, the guide tube 40 and the first cam tube 50 advance and retract integrally in the optical axis direction while relatively rotating.

  Further, as shown in FIG. 5, the cam cylinder 50 has clearance groove holes 55 a, 55 b, and 55 c that are opened at the front end portion of the cam cylinder 50 at equal intervals along the optical axis direction. Yes.

  The second cam cylinder 60 is fitted to the inner peripheral surface of the guide cylinder 40 and the outer peripheral surface of the first cam cylinder 50. On the outer peripheral surface on the base end side of the second cam cylinder 60, rotationally driven pins 61a, 61b, 61c are formed to protrude outward at equal intervals of 120 ° around the optical axis. These rotation driven pins 61a, 61b, 61c are respectively fitted in rotation driving key grooves 44a, 44b, 44c formed in the inner surface of the guide tube 40 along the optical axis direction.

  Further, cam pins 62a, 62b, and 62c are formed to protrude inwardly at positions corresponding to the rotation driven pins 61a, 61b, and 61c on the inner peripheral surface of the second cam cylinder 60, respectively. 62a, 62b, and 62c are fitted in inclined cam grooves 51a, 51b, and 51c (see FIG. 5) formed on the outer peripheral surface of the first cam cylinder 50 at regular intervals. Accordingly, the second cam cylinder 60 rotates in synchronization with the rotation of the guide cylinder 40 and advances and retreats in the optical axis direction along the inclined cam grooves 51 a to 51 c of the first cam cylinder 50.

  As shown in FIG. 5, inclined cam grooves 63a-1, 63a-2, 63a-3 having a plurality of gentle bent portions are formed on the inner peripheral surface of the second cam cylinder 60 at regular intervals. ing. The base end sides of these inclined cam grooves 63a-1, 63a-2, 63a-3 are communicated with each other by assembling guide cam grooves 63b-1, 63b-2, 63b-3. The end side is communicated with the tip end side of the insertion insertion cam grooves 63c-1, 63c-2, 63c-3 opened at the base end portion of the second cam cylinder 60.

  The zoom cylinder 80 is disposed near the proximal end of the inner peripheral surface of the second cam cylinder 60, and the zoom cylinder 80 is fitted to the inner peripheral surface of the first cam cylinder 50. ing. On the outer peripheral surface on the proximal end side of the zoom cylinder 80, rotation prevention keys 84a, 84b, 84c and 84d (only the rotation prevention keys 84a and 84b are shown in FIG. 2) are substantially 90 with respect to each other about the optical axis. The rotation stop keys 84a, 84b, 84c, 84d are formed on the inner circumference of the first cam 50 along the optical axis direction. The straight keyways 54a, 54b, 54c, and 54d (see FIGS. 2 and 5) are respectively fitted.

  On the outer peripheral surface of the zoom cylinder 80, cam pins 81a, 81b, 81c are formed outwardly projecting at equal intervals of 120 ° around the optical axis, and these cam pins 81a, 81b, 81c is fitted to the inclined cams 63a-2, 63a-3, 63a-1. Accordingly, the zoom cylinder 80 advances and retreats along the inclined cams 63a-2, 63a-3, 63a-1 in the optical axis direction. The cam pins 81a, 81b, 81c are positioned at 81aT, 81bT, 81cT in FIG. 5 in the tele state of the zoom lens barrel shown in FIG.

  Near the tip of the inner peripheral surface of the second cam cylinder 60, the first group cylinder 70 holding the first lens group 120 at the tip is fitted. Cam pins 71a, 71b, 71c are formed on the outer peripheral surface of the base end side of the first group cylinder 70 so as to protrude outward at equal intervals of 120 ° around the optical axis. 71a, 71b, 71c are fitted to the inclined cams 63a-1, 63a-2, 63a-3, respectively. Accordingly, the first group cylinder 70 advances and retreats along the cams 63a-1 to 63a-3 in the optical axis direction. The cam pins 71a, 71b, 71c are located at 71aT, 71bT, 71cT in FIG. 5 in the telephoto state of the zoom lens barrel shown in FIG.

  Further, the cam pins 71a, b, c and the cam pins 81b, c, a come into the escape groove holes 55a, 55b, 55c while the zoom lens barrel shifts from the tele state to the wide state. (See FIG. 3).

  An anti-rotation groove 73 is formed along the optical axis direction on the inner surface of the first group cylinder 70, and an anti-rotation 82 b formed to protrude from the tip of the zoom cylinder 80 is formed in the anti-rotation groove 73. Key is fitted.

  The distal end side of the zoom shaft 72 is fitted in the wall of the first group cylinder 70, and the proximal end side of the zoom shaft 72 is bored in an inward flange formed at the distal end of the zoom cylinder 80. It penetrates the provided bearing hole 82 and is engaged with the third group cylinder 100. The zoom shaft 72 will be described in detail later when the configuration of the third group cylinder 100 is described.

  Inside the zoom cylinder 80, a second group cylinder 90 holding the second lens group 130 is disposed. A second group lid 150 is fitted on the outer peripheral surface on the proximal end side of the second lens group 130, and the guide shaft 91 is supported by the second group cylinder 90 and the second group lid 150. ing. The guide shaft 91 is fitted into a bearing (not shown) formed on the zoom cylinder 80, whereby the second lens group 130 is supported so as to be relatively movable in the optical axis direction with respect to the zoom cylinder 80. ing.

  An anti-rotation pin (not shown) is formed on the outer peripheral surface of the second group cylinder 90, and the anti-rotation pin is fitted in an anti-rotation groove (not shown) formed on the inner peripheral surface of the zoom cylinder 80. Thus, the rotation of the second group cylinder 90 relative to the zoom cylinder 80 is restricted.

  The front end surface of the second group cylinder 90 is formed as a sector receiving surface 93, and a sector 96 is supported on the sector receiving surface 93. The sector 96 is driven by a plunger 110 that is a sector driving actuator disposed on the outer peripheral surface of the second group cylinder 90.

  Further, the second group cylinder 90 is provided with a screw feed mechanism for driving the second group cylinder 90 in the optical axis direction and moving the second group cylinder 90 relative to the zoom cylinder 80 for focusing.

  Here, with reference to FIG. 7, this screw feed mechanism will be described in some detail.

  The screw feed mechanism 170 has a screw shaft 172 whose rotation axis is the optical axis direction. Shaft portions 171 a and 171 b are formed at both ends of the screw shaft 172, and these shaft portions 171 a and 171 b are bearings formed on the outward flanges of the second group cylinder 90 and the second group lid 150. The holes 95 and 155 are rotatably supported.

  A gear portion 173 is fixed to the tip end side of the screw shaft 172, and the gear portion 173 is engaged with a driving gear of a focusing motor (not shown).

  A male screw is formed on the base end side of the screw shaft 172 with respect to the gear portion 173, and a nut 180 is screwed to the male screw. A rotation stop pin 181 is formed on the outer peripheral surface of the nut 180, and the rotation stop pin 181 is fitted in a rotation stop groove (not shown) formed in the second group lid 150.

  Further, the base end side of the screw shaft 172 from the portion where the nut 180 is screwed is inserted into a through-hole of a contact projection 85 formed inwardly projecting from the inner peripheral surface of the zoom cylinder 80. Yes.

  A compression spring 190 is disposed on the outer periphery of the screw shaft 172 and between the abutting protrusion 85 and the second group lid 150. The contact protrusion 85 is in contact with the base end surface of the nut 180 by the urging force of the compression spring 190.

  A third group cylinder 100 holding the third lens group 140 is disposed on the inner peripheral surface of the zoom cylinder 80 closer to the base end than the second group cylinder 90. The third group cylinder 100 is provided with a shaft portion (not shown), and this shaft portion is fitted to a bearing (not shown) formed on the zoom tube 80 so that the optical axis with respect to the zoom tube 80 is provided. It is held so as to be relatively movable in the direction.

  Further, a rotation stop groove 102 is formed on the distal end side of the third group cylinder 100, and this rotation stop groove 102 is fitted to a rotation stop pin 83 formed to protrude from the inner surface of the zoom cylinder 80. Yes.

  Further, an outward flange is formed on the distal end side of the third group cylinder 100, and the zoom shaft 72 is inserted into a thrust receiving hole 103 formed in the outward flange. A stopper 72 a is formed at the base end of the zoom shaft 72 to prevent the zoom shaft 72 from coming out of the thrust receiving hole 103. A compression spring (not shown) is disposed on the outer periphery of the zoom shaft 72 between the inward flange of the zoom cylinder 80 and the outward flange of the third group cylinder 100. The third group cylinder 100 is biased toward the proximal end side of the zoom shaft 72.

  The zoom lens barrel configured as described above is driven and controlled by, for example, a drive control device shown in FIG.

  In this drive control device, a CPU 802 and a motor driver circuit 803 that supplies drive power to a plurality of drive motors based on a drive signal from the CPU are connected by signal lines. Further, the CPU 802 and the motor driver circuit A battery 801 that supplies power to 803 is connected to form a main part.

  The CPU 802 is connected to a main switch 804 of the camera and a plurality of switches (not shown), sensors, a photo interrupter, a photo reflector, and the like. Is output to the motor driver circuit.

  Driving motors M1, M2, and M3 are connected to the motor driver circuit 803 as a focusing motor 805, a zooming motor 806, and a setup motor 807, respectively, and when a driving signal is input from the CPU 802, Drive power is supplied to each of the motors according to the drive signal. In this embodiment, three drive motors are used. However, depending on the zoom lens barrel to be applied, one or two drive motors are mechanically switched, and the drive force thereof is not driven. It may be transmitted to the unit, or three or more drive motors may be used.

  Next, the operation of the zoom lens barrel from the tele state (see FIG. 1) to the wide state (see FIG. 3) will be described.

  A drive signal is input from the CPU 802 to the motor driver circuit 803, and the zoom motor 806 is activated based on the drive signal. The rotational driving force from the zoom motor 806 is transmitted to the gear unit 35.

  The rotating cylinder 30 is rotated in the wide direction by this rotational driving force. Then, the guide cylinder 40 rotates integrally with the rotary cylinder 30 via the rotation drive pin 43 fitted in the rotation drive key groove 33 of the rotary cylinder 30 and the movable cylinder 20 is inclined. Retreat along the cam grooves (holes) 21a, b, c. At this time, the first cam cylinder 50 moves backward integrally with the guide cylinder 40 in a state where the rotation is restricted by the guide key 53 fitted in the rectilinear key groove 23.

  The rotational driving force of the guide cylinder 40 is transmitted to the second cam cylinder 60 via the rotationally driven pins 61a, b, c fitted in the rotational driving key grooves 44a, b, c, and the second cam cylinder 60. The cam cylinder 60 rotates integrally with the guide cylinder 40 and retreats along the inclined cams 51a, b, and c.

  In addition, when the second cam cylinder 60 is rotated, the zoom cam 80 is tilted in the inclined cam groove 63a− in a state where the rotation of the zoom cylinder 80 is restricted by the straight key grooves 54a, b, c, d of the cam cylinder 50. The first group cylinder 70 is retracted by cam pins 81c, b, a fitted to 1, 63a-2, 63a-3, and the rotation of the first group cylinder 70 is restricted by the rotation stopper 82b of the zoom cylinder 80. The cam pins 71a, b, c fitted to the inclined cams 63a-1, 63b-2, 63a-3 are moved backward.

  At this time, the second group cylinder 90 moves backward together with the zoom cylinder 80. Further, the third group cylinder 100 is always urged toward the proximal end side of the zoom shaft 72 by a compression spring (not shown) disposed between the inward flange of the zoom cylinder 80 and the outward flange of the third group cylinder 100. Accordingly, the first group cylinder 70 holding the zoom shaft 72 is moved backward integrally.

  In this way, each lens group moves in the optical axis direction, and zooming is performed. The zoom lens barrel is provided with a wide position detection sensor (not shown). When the wide front position is detected by the sensor, this detection signal is sent to the CPU 802 and zoomed based on the detection signal. The motor 806 is controlled to stop the rotation of the rotary cylinder 30 at the timing when the lens barrel is at the wide position.

  Here, when the zoom lens barrel is moved from the tele position to the wide position, the cam pins 71a, b, c and the cam pins 81a, b, c are changed to 71aT, 71bT, 71cT, 81aT, 81bT, 81cT in FIG. It moves from the position shown to the position shown to 71aW, 71bW, 71cW and 81aW, 81bW, 81cW.

  Next, focusing on the zoom lens barrel will be described.

  When a driving signal is input from the CPU 802 to the motor driver circuit 803 and the focusing motor 805 is activated based on the driving signal, the rotational driving force from the focusing motor 805 is transmitted to the gear unit 173 (see FIG. 7). The screw shaft 172 rotates.

  At this time, since the nut 180 is prevented from rotating by the second group lid 150, the nut 180 advances and retreats in the optical axis direction according to the male screw lead of the screw shaft 172.

  Since the contact protrusion 85 is pressed against the nut 180 by the compression spring 190, as a result, the second group cylinder 90 and the zoom cylinder 80 move relative to each other as the nut 180 moves forward and backward. Focusing is performed.

  Next, the retracting operation of the zoom lens barrel will be described.

  First, the focusing motor 805 is energized, the second group cylinder 90 is moved relative to the zoom cylinder 80, and is fed out to the closest position in front. That is, the space between the first lens group 120 and the second lens group 130 is reduced to the limit position, and a space for housing the third lens group 140 is formed on the base end side of the second lens group 130.

  Next, the zoom motor 806 is energized to bring the lens barrel into a wide state, and then the zoom motor 806 is continuously driven in the wide direction. Then, the thrust receiving groove 34 of the rotating cylinder 30 and the bayonet type thrust receiving of the camera body 160 are disengaged.

  Next, the setup motor 807 is energized to move each lens barrel together with the moving plate 10 in the retracted direction. Then, the base end side of the third group cylinder 100 is brought into contact with the protrusion 161 of the camera body 160, and the thrust receiving hole 103 of the third group cylinder 100 and the stopper 72a of the zoom shaft 72 are separated from each other. The third group cylinder 100 moves while compressing and charging a compression spring disposed on the zoom shaft 72, and is housed in a housing space formed on the base end side of the second lens group 130, and is also a zoom lens mirror. The tube is in the retracted state with the shortest overall length.

  Thus, before retracting, the second lens group 130, which is the focus lens group, is extended forward to create a storage space on the base end side of the second lens group 130, thereby reducing the total length of the lens barrel when retracted. can do.

  Next, the electrical sequence of the drive control device in which the zoom lens barrel controls the retracting operation will be described.

  FIG. 10 is a flowchart showing an electrical sequence of the drive control device when the zoom lens barrel is retracted.

  In the present embodiment, the zoom lens barrel starts to retract when the main switch 804 of the camera body connected to the CPU 802 of the drive control device is turned off. In step S901, the zoom lens barrel starts the main operation. When the switch 804 is turned off, the process proceeds to step S902, the drive motor M1 (focusing motor 805) is energized, and the second group cylinder 90 is operated toward the closest position.

  Next, the process proceeds to step S903, where it is determined whether or not the second group cylinder 90 has reached the close position. If it is determined that the second group cylinder 90 has reached the close position, the process proceeds to step S904 and the drive After the energization of the motor M1 is turned off, the process proceeds to step S905.

  In step S905, the drive motor M2 (zoom motor 806) is energized to activate the zoom lens barrel in the wide direction, and then the process proceeds to step S906.

  In step S906, it is determined whether the zoom lens barrel is in the wide state and the bayonet-type thrust receiver of the camera body 160 is detached from the thrust receiver groove 34 of the rotary cylinder 30, and the thrust receiver groove 34 If it is determined that the bayonet-type thrust receiver has been detached, the process proceeds to step S907, and energization of the drive motor M2 is turned off.

  Next, the process proceeds to step S908, the drive motor M3 (setup motor 807) is energized to start the movable plate 10 in the retracted direction, and then the process proceeds to step S909.

  In step S909, it is determined whether or not the moving plate 10 has been moved to the retracted position. If it is determined that the moving plate 10 has been moved to the retracted position, the process proceeds to step S910 to the drive motor M3. Turn off the power and exit the routine. That is, the process returns to the main routine to stop the camera operation.

  As described above, the retracting control of the drive control device is performed.

  Further, the retracting control of the drive control device may be programmed to follow the routine shown in FIG.

  FIG. 11 is a flowchart showing an electrical sequence of the drive control device when the zoom lens barrel is retracted.

  This control is different from the control means shown in FIG. 10 in that the zoom lens barrel is first set to the wide state before the second group cylinder 90 is moved to the closest position.

  When the main switch 804 of the camera body connected to the drive control device is turned off in step S920, the process proceeds to step S921, where the drive motor M2 is energized and the zoom lens barrel is activated in the wide direction. Go to step 922.

  In step S922, it is determined whether or not the zoom lens barrel has been moved to the wide position. If it is determined that the zoom lens barrel has been moved to the wide position, the process proceeds to step S923, and the drive motor M2 is energized. Turn off.

  Next, the process proceeds to step S924, the drive motor M1 (focusing motor 805) is energized to drive the second group cylinder 90 toward the closest position, and then the process proceeds to step S925.

  In step S925, it is determined whether or not the second group cylinder 90 has reached the close position. If it is determined that the second group cylinder 90 has reached the close position, the process proceeds to step S926, and the drive motor After the energization of M1 is turned off, the process proceeds to step S927.

  Hereinafter, the control after step S927 is the same as the control after step S910 shown in FIG.

  Thus, after the zoom lens barrel is once set to the wide position, the second group cylinder 90 can be moved to the closest position, and the drive motor M2 can be driven again.

  In the control means shown in FIGS. 10 and 11 above, when the second group cylinder 90 supporting the second lens group 130 is retracted forward when retracted, it is extended to the foremost closest position. It is also possible to feed a predetermined amount from the retracted position to the close direction side without moving to the close position.

  Next, characteristics of the inclined cam groove 63a of the second cam cylinder 60 will be described based on the cam development view of FIG.

  The inclined cam groove 63a-1 of the second cam cylinder 60 has a cam groove portion used between the wide position 71aW and the tele position 71aT by the cam pin 71a of the first group cylinder 70 and the cam pin 81c of the zoom cylinder 80 at the wide position 81cW. And a cam portion used between the tele position 81cT.

  In the inclined cam groove 63a, the cam groove between the wide position 71aW and the tele position 81cT is a cam groove near the wide position of the first group cylinder 70 and at the same time near the tele position of the zoom cylinder 80. It is also a cam groove. That is, one cam groove is shared and overlapped as two different cylinder driving cam grooves.

  By sharing one cam groove in this way, the degree of freedom of cam groove layout is increased, and the rotation angle is set to be large so that the overall length of the cylinder can be shortened or the pressure angle can be reduced even if the cylinder diameter is small. it can.

  Such common use of the cam groove is possible when the zoom movement is performed by combining two or more cam grooves.

  Next, a method for designing the inclined cam groove 63a shown in FIG. 5 will be described with reference to the graph diagrams of FIGS. 8 (a) and 8 (b).

  In this graph diagram, the amounts of extension of the first lens barrel 70 and the zoom cylinder 80 (second lens barrel 90) with respect to the rotation angles of the two lens cylinders are indicated by 1Z and 2Z in FIG. This is a case where the inclined cam groove 63a for designing a zoom lens barrel having a payout characteristic is designed. The amount of movement of the zoom lens barrel relative to the rotation angle of the second cam barrel 60 is assumed to change linearly as shown in FIG.

  In this case, the cam grooves for individually driving the first group cylinder 70 and the zoom cylinder 80 necessary for the second cam cylinder 60 in order to obtain the extension characteristics 1Z, 2Z are the above-mentioned extension characteristics 1Z. , 2Z is obtained by subtracting the amount of movement of the second cam cylinder 60 from the cams having the shapes indicated by 1Z ′ and 2Z ′ in FIG.

  Next, in order to partially share the tele side which is one end of the cam groove 2Z ′ and the wide side of the cam groove 1Z ′, as shown in FIG. 8B, a wide position which is one end of 1Z ′. On the 2Z 'cam.

  Then, a cam groove having a path of 2Z′W to 1Z′W to 1Z′T is formed as a combined cam groove of the cam grooves 1Z ′ and 2Z ′. Considering that the first group cylinder 70 and the zoom cylinder 80 are moved along the cam groove, each cylinder is extended as shown by 1Z and 2Z in FIG. 8A from the rotation angles 2Z′W to 1Z′W. Move along the characteristics.

  However, when the rotation angle exceeds 1Z′W, the zoom cylinder 80 moves along the cam groove for the first group cylinder 70, and is thus extended too much. Therefore, this is corrected by the feed amount of the second cam cylinder 60 (correction cam 1). Then, since the first group cylinder 70 is insufficiently extended by the correction cam 1 of the second cam cylinder 60, the tele-side cam groove portion, which is the other end for the first group cylinder 70, is equivalent to the correction cam 1. Correction is performed (correction cam 2). That is, the correction cam 2 corrects the group interval between the first group lens 120 and the second group lens 130, and the amount of deviation by this correction, that is, the entire lens including the first group lens and the second group lens. Is corrected by the correction cam 1. In this way, it is possible to design a synthetic cam groove that connects two cam grooves and can share a part.

  Further, as a correction method of each cam groove at the time of designing the synthetic cam groove, the tele position which is one end of the cam groove 2Z ′ is brought directly on (overlapped with) the cam groove 1Z ′ (first position), There is also a method of correcting by a wide-side extension of the two-cam barrel 60 and a wide-side extension (the other end) of the cam groove 2Z ′. Further, there are various methods such as correction on both the wide side and the tele side of the second cam cylinder 60 and the correction on both the wide side and the tele side of the cam groove 1Z ′ and the cam groove 2Z ′. There is a combination method.

  The cam groove 63 b of the second cam cylinder 60 shown in FIG. 5 is a guide cam for assembly when the cam pins 81 a, 81 b, 81 c of the zoom cylinder 80 are fitted to the second cam cylinder 60.

  The assembling method of the cam pins will be described by taking the cam pins 71a and 81a as an example. After the cam pins 71a and 81a are inserted from the cam grooves 63c-1 of the second cam cylinder 60, the cam pins 71a are inserted into the cam grooves 63a-1. , The cam pin 81a is moved along the cam groove 63b-1, the cam pin 71a is moved to a position 71aw on the cam groove 63a-1, and the cam pin 81a is moved to the cam groove 63b-1. To the cam groove 63a-2, move to the 81aw position, and are assembled to the use state wide position.

  As described above, according to the above-described embodiment, a plurality of cam grooves for operating a plurality of lens groups by connecting a plurality of different cam grooves can be shared. Even when it is necessary to form a groove, it is possible to ensure a sufficient range of movement of each lens group without increasing the size of the cam barrel, and to increase the degree of freedom of cam layout, thereby improving the mirror. The entire tube can be made short and thin.

  Also, when the zoom lens barrel is retracted, the focus lens group can be extended to the closest position to reduce the extra space between each lens group, so there is no need to provide a special member or mechanism. The overall length can be shortened.

  Note that the present invention is not limited to the above-described embodiment, and various modifications and applications can of course be implemented without departing from the spirit of the invention. Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and the effect described in the effect of the invention Can be obtained as an invention.

1 is a cross-sectional view of a zoom lens barrel according to an embodiment of the present invention in a tele state and cut at an angular position of 120 ° around an optical axis when viewed from the front. FIG. 2 is a cross-sectional view of a main part showing only the vicinity of a fitting portion between a first cam cylinder and a zoom cylinder of the zoom lens barrel of FIG. 1. FIG. 2 is a cross-sectional view of the zoom lens barrel of FIG. 1 taken in a wide state and cut at an angular position of 120 ° around the optical axis when viewed from the front. FIG. 2 is a cross-sectional view of the zoom lens barrel of FIG. 1 in a retracted state and cut at an angular position of 120 ° around the optical axis when viewed from the front. FIG. 3 is a development view showing shapes of cam grooves of a movable cylinder, a first cam cylinder, and a second cam cylinder in the tele state of the zoom lens barrel of FIG. 1. The perspective view of the principal part of the guide cylinder in the zoom lens barrel of FIG. FIG. 2 is a perspective view showing a feed screw mechanism that performs focusing of the zoom lens barrel of FIG. 1. FIG. 2 is a graph diagram when designing the rotation angle and the feed amount of each tube in the zoom lens barrel of FIG. 1. The block block diagram which shows the drive control apparatus of the zoom lens barrel of FIG. The flowchart which shows the electrical sequence of the drive control apparatus of FIG. The flowchart which shows the electrical sequence of the drive control apparatus of FIG. Explanatory drawing which shows the positional relationship of each lens group of the conventional zoom lens barrel.

Explanation of symbols

60 …… Second cam cylinder 63a1,2,3 ...... Inclined cam groove 70 …… First group cylinder 80 …… Zoom cylinder 90 …… Second group cylinder 120 …… First lens group 130 …… Second lens group

Claims (1)

In a zoom lens barrel that performs zooming by moving each of a plurality of lens groups constituting an imaging optical system in the optical axis direction,
A first lens group of the plurality of lens groups;
A second lens group of the plurality of lens groups;
A first cam region for moving the first lens group in the optical axis direction and a second cam region for moving the second lens group in the optical axis direction, and performing the zooming. In this case, a partial region of the first cam region and the second cam region is overlapped, and the overlap region is used in common, and a group for zooming between the first lens group and the second lens group A cam formed between the first cam region and the second cam region,
A zoom lens barrel characterized by comprising:

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