JP2009075328A - Lens barrel - Google Patents

Abstract

A cam follower prevents a cam groove from being damaged when an external force is applied to a moving cylinder.
A cam follower 30 provided on an outer periphery of a moving cylinder 11 is engaged with a cam groove 31 provided on an inner surface of the cam cylinder 13, and the moving cylinder 11 is rotated in the optical axis direction by rotating the cam cylinder 13. Move. The cam follower 30 is in contact with the cam surface 38 in front of the optical axis in the cam groove 31 by a spring that is biased. The cam groove 31 has a larger inclination angle than the cam surface 38 with respect to the surface perpendicular to the optical axis of the other play cam surface 37. Thereby, even if an external force is applied to the movable cylinder 11 and the cam follower 30 is detached from the cam groove 31, the play cam surface 37 is not easily damaged because the play cam surface 37 has a large inclination angle.
[Selection] Figure 5

Description

  The present invention relates to a lens barrel that includes a cam mechanism that moves a lens in the optical axis direction, and more particularly to a lens barrel that includes a cam mechanism having a cam follower and a cam surface.

  Conventionally, a cam mechanism is used in a zoom lens barrel or the like. The cam mechanism is a mechanism that converts rotational drive into straight drive. For example, a cam follower is provided in a moving cylinder that holds a lens, and a cam groove is provided in a cam cylinder that is an outer cylinder, and the cam cylinder is rotated to move the moving cylinder. By rotating the rotation, the moving cylinder is moved linearly in the optical axis direction with respect to the cam cylinder.

  By the way, the cam cylinder includes a metal one and a resin one. Metallic ones are expensive because the cam grooves are made by cutting, whereas those made of grease are low cost because they are made by molding. However, in the cam cylinder of the mold molding, the cam groove has a trapezoidal section due to the need for the draft angle of the mold, and the head of the mating cam follower that engages with the cam groove is accordingly a trapezoidal section with a trapezoidal section. It becomes a cone. For this reason, when a load is applied to the movable cylinder from the outside, the inclined surfaces of the cam follower and the cam groove may slide to remove the follower biting from the cam groove. When this happens, the cam mechanism does not operate.

  Therefore, the cam follower is composed of a taper pin and a tapered surface portion provided outside the movable cylinder, and the taper pin has a protruding position where the tip protrudes radially outward from the tapered surface portion and a retracted position where the taper pin enters inward. When the moving cylinder receives an external force in the direction of the optical axis, the taper pin is pushed by the cam groove and moved to the retracted position. A lens barrel and cylindrical member fitting mechanism that prevents the cam follower from coming off from the cam groove by retracting the taper surface part against a part of the cam groove has been proposed (Patent Document 1).

In addition, the cam follower is provided with two inclined surfaces having different angles, and the cam groove is provided with a cam surface corresponding to the inclined surface, and the angle of the inclined surface on the side facing the external force from the front of the optical axis among the inclined surfaces of the cam groove is set. A lens barrel that prevents the cam follower from detaching from the cam groove by preventing the cam follower from moving in the detaching direction by using a steep slope has been proposed. (Patent Document 2).
JP-A-6-250063 JP 2003-15013 A

  However, since the invention described in Patent Document 1 requires a cam follower, a cam groove and a plurality of parts around the cam groove, and requires a complicated shape, the lens barrel is increased in size and the processing / assembly cost is increased. Easy to invite.

  In the invention described in Patent Document 2, there is no problem if the load is small. On the other hand, if the load is large, the cam follower may bite into the slope of the cam groove and damage the slope. Once bited in, it is difficult to escape, and the cam follower does not slide smoothly at the scratched position, and the lens stopping accuracy decreases at this position.

  Further, the load applied to the moving cylinder includes a load applied from a direction perpendicular to the optical axis with respect to the front end of the moving cylinder. In this case, the movable cylinder rotates around the rear end in a direction in which the front end is inclined with respect to the optical axis. In such a case, since the cam follower slope rotates and slides over the slope of the cam groove, the cam follower cannot be effectively prevented from coming off the cam groove.

  The present invention provides a lens device that solves the above-described drawbacks of the prior art and is devised so that the cam groove is not easily damaged by the cam follower. It is another object of the present invention to provide a lens device that is devised to re-engage even when the cam follower is removed from the cam groove.

  Therefore, in the lens device of the present invention, a biasing means for biasing the cam follower toward the cam surface in front of the optical axis of the two cam surfaces constituting the cam groove is provided, and the cam follower is biased by the biasing means. The angle of inclination of the other cam surface (play cam surface) with respect to the surface perpendicular to the optical axis is larger than the cam surface with which the cam contacts. According to this, since the inclination angle of the play cam surface is increased, the impact force that the cam follower escapes in the direction of the optical axis and contacts the play cam surface when an external force is applied to the movable cylinder can be reduced. It is possible to prevent the surface from being scratched or damaged as much as possible. Note that the entire cam groove may be used as the range in which the inclination angle of the play cam surface is increased. Further, when the moving cylinder advances and retreats at the time of zooming, it may be a range in which the cam follower is located at the photographing preparation position in the moving range of the moving cylinder, for example, the wide position. Furthermore, when the moving cylinder is retracted to the retracted position stored inside the cam cylinder, the cam follower is located within the range where the zoom is moved forward from the optical axis and zoomed between the wide position and the tele position. It is good only as well.

  By the way, there are cases where a large number of light shielding grooves for preventing internal reflection are provided on the inner surface of the cam cylinder. If the light shielding groove is provided as far as the edge of the play cam surface, the cam follower detached from the cam groove may be caught in the light shielding groove and cannot be returned to the cam groove. Therefore, it is desirable to provide a light shielding groove at a predetermined distance from the play cam surface toward the rear of the optical axis.

  It is desirable to return the cam follower to the cam groove when the cam follower is detached from the cam groove. Therefore, a sub cam groove for returning the cam follower to the cam groove is provided. The auxiliary cam groove has one end connected to the cam groove, and the remainder from the one end is provided at a predetermined distance from the play cam surface toward the rear of the optical axis. According to this, since the auxiliary cam groove is provided at the rear of the optical axis of the cam groove, the cam follower removed from the cam groove enters the auxiliary cam groove. Here, if the cam cylinder is rotated, the sub cam groove guides the cam follower into the cam groove, so that the cam floor surely enters the cam groove. The secondary cam is connected to the play cam surface side of the cam groove. If the cam follower is returned to the cam groove, the cam follower slides only on the cam surface by the urging force of the urging means, so that it does not enter the sub cam groove.

  When using a cam cylinder provided with a secondary cam, it is preferable to perform a return operation to return the cam follower from the secondary cam groove to the cam groove by automatically rotating the cam cylinder and stopping the movement of the lens. . In this case, at least one end of the cam follower is detected in response to detecting that the cam follower is out of the cam groove and the moving cylinder is inclined with respect to the optical axis, and the detecting means detects the inclination of the moving cylinder. Returning operation control means for rotating the cam cylinder to a position where it returns to the cam groove may be provided. As this detection means, it may be detected using an encoder whether or not the cam cylinder or the motor driving the cam cylinder is rotating and whether or not the rotation is slow. Further, when used in a contrast AF type electronic camera, it can be performed by detecting whether or not another area is out of focus with respect to a specific area of the screen.

  Further, an impact detection means for detecting that an external impact has been applied to the lens device, and a cam cylinder to a position where the cam follower returns to the cam groove at least beyond one end in response to the impact detection means detecting the impact. Return operation control means for rotating the motor.

  In some cases, a reinforcing ring is provided at the front end of the optical axis of the cam barrel. This reinforcing ring is a ring member in which a cross-sectional L-shaped portion formed of one end covering the front end of the cam cylinder in front of the optical axis and the other end covering the outer periphery of the cam cylinder is formed in an annular shape. Yes. When using a cam cylinder with this reinforcing ring, when an external force is applied to the moving cylinder and the moving cylinder is tilted, one end of the reinforcing ring bites into the outer surface of the moving cylinder and loads relative rotation with each other. There is a risk of applying. Therefore, it is desirable to fold one end toward the imaging plane side. Further, by rounding the corner portion where one end is turned back to have a smooth surface, it is possible to reliably prevent biting into the moving cylinder.

  Further, an elastic member may be provided at one end of the reinforcing ring, and the elastic member may be interposed between the one end and the outer periphery of the moving cylinder, thereby preventing the biting into the moving cylinder with certainty. Further, when the light shielding rib that contacts the outer surface of the moving cylinder is provided integrally with the elastic member, harmful light can be prevented from entering through the gap between the moving cylinder and the cam cylinder and the biting into the moving cylinder can also be prevented. In addition, it is possible to prevent dust and foreign matter from entering through the gap between the moving cylinder and the cam cylinder. Since the light shielding rib is always in contact with the outer surface of the movable cylinder, it is preferable to perform a process of coating a solid lubricant having a low frictional resistance.

  As a measure to prevent the moving tube from biting, instead of providing an elastic member, a concave portion is provided on the outer surface of the moving tube, and this recessed portion contacts the inner corner of the front end of the optical axis of the cam tube or one end of the reinforcing ring. May be absorbed. As this recessed part, it is desirable to form in the shape connected to the whole circumferential direction of the outer periphery of a movable cylinder. In addition, the position where the concave portion is provided is set in a range where the inner corner of the tip of the cam barrel in the optical axis direction bites into the cam barrel when the lens barrel is in the photographing preparation position. Is desirable. A plurality of recesses may be provided in the optical axis direction.

  In the present invention, since the inclination angle of the other cam surface (play cam surface) with respect to the surface perpendicular to the optical axis is larger than the cam surface with which the cam follower abuts by the biasing means, an external force is applied to the movable cylinder. Sometimes, the impact force of the cam follower escaping in the direction of the optical axis and abutting on the play cam surface can be reduced, and it is possible to prevent the play cam surface from being scratched or damaged as much as possible.

[First Embodiment]
The lens apparatus 10 of the present invention is a zoom lens apparatus, and as shown in FIGS. 1 and 2, a movable cylinder 11, a rear lens group holding cylinder 12, a cam cylinder 13, a rectilinear cylinder 14, a fixed cylinder 15, and The rotating cylinder 16 is comprised. A front lens group 17 is held on the movable cylinder 11. The front lens group 17 and the rear lens group 18 held in the rear lens group holding cylinder 12 are moved in the direction of the optical axis so as to change the distance from each other, thereby performing zooming. The lens device 10 is a step zoom type device that performs zooming and focusing using a single motor 19.

  A rotary cylinder 16 is rotatably provided on the outer periphery of the fixed cylinder 15. The rotation of the motor 19 is transmitted to the rotating cylinder 16. The rotary cylinder 16 has a rectilinear groove 21 that engages with a cam follower 20 provided in the cam cylinder 13 on the inner periphery, and the rectilinear groove 21 transmits the rotation of the rotary cylinder 16 to the cam cylinder 13 via the cam follower 20. To do. The fixed cylinder 15 is provided with a cam opening 22 that engages with a cam follower 20 provided in the cam cylinder 13. The cam opening 22 moves the cam cylinder 13 in the optical axis direction.

  The cam barrel 13 moves in the optical axis direction while rotating together with the movable barrel 11, the rear lens group holding barrel 12, and the rectilinear barrel 14. The rectilinear cylinder 14 is rotatably held with respect to the cam cylinder 13 and includes a rectilinear protrusion 24 arranged on the front side and a protrusion 25 arranged on the rear side. The rectilinear protrusion 24 engages with a rectilinear groove 26 provided on the inner surface of the movable cylinder 11 to stop the rotation of the movable cylinder 11, and the protrusion 25 is provided in a rectilinear groove 27 provided on the inner surface of the fixed cylinder 15. Engage to lock itself.

  The rectilinear cylinder 14 supports the rear lens group holding cylinder 12 on the inner surface so as to be movable in the optical axis direction. The rectilinear cylinder 14 has a rectilinear guide opening 28 formed on the peripheral surface thereof. A cam follower 29 provided in the rear lens group holding cylinder 12 is engaged with the rectilinear guide opening 28 to stop the rotation of the rear lens group holding cylinder 12.

  The movable cylinder 11 is provided with a cam follower 30 at the outer peripheral rear end. Formed on the inner surface of the cam cylinder 13 are a first cam groove 31 that engages with the cam follower 30 of the movable cylinder 11 and a second cam groove 32 that engages with the cam follower 29 of the rear lens group holding cylinder 12. . Thus, in the lens device 10, when the rotating cylinder 16 rotates, the cam cylinder 13 moves in front of the optical axis with respect to the fixed cylinder 15, and the moving cylinder 11 moves in the optical axis direction with respect to the cam cylinder 13. From the retracted position (non-photographing position) shown in FIG. 1 to the zoom position at the tele end via the wide end shown in FIG. At the retracted position, the cam cylinder 13 is housed inside the fixed cylinder 15 and the movable cylinder 11 is housed inside the cam cylinder 13. At the wide end, the cam cylinder 13 is located relative to the fixed cylinder 15. However, the movable cylinder 11 protrudes most from the cam cylinder 13.

  Note that an imaging sensor 35 such as a CCD having a light receiving surface arranged on the imaging surface of the lens device 10 is fixed to the fixed cylinder 15. The first and second cam grooves 31, 32 are in the first zoom position, then in the focusing range at the first zoom position, then in the second zoom position, and in the second zoom position. The cam surface is composed of a cam surface obtained by combining a zoom cam surface and a focusing cam surface so that a focusing range is obtained.

  The cam cylinder 13 is made by molding with a resin material, and the first and second cam grooves 31 and 32 each have a trapezoidal cross section for die cutting. The cam followers 29 and 30 abut against any one of the pair of slopes constituting the cam grooves 31 and 32 by a spring 36 for shifting in order to prevent the cam grooves 31 and 32 from rattling. ing. The spring 36 is a compression coil spring provided between the movable cylinder 11 and the rear lens group holding cylinder 12. The cam follower 30 provided in the movable cylinder 11 by the bias of the spring 36 is arranged on the subject-side slope (cam surface) of the first cam groove 31 and the cam follower 29 provided in the rear lens group holding cylinder 12 is second. Each of the cam grooves 32 abuts on a slope (cam surface) on the imaging side. The cam followers 29 and 30 and the cam grooves 31 and 32 are respectively arranged at three division positions in the circumferential direction around the optical axis.

  Conventionally, the cam groove is composed of a cam surface that abuts the cam follower by displacing, and a play cam surface that faces the cam surface, and the cam surface and the play cam surface have substantially the same inclination angle with respect to the surface orthogonal to the optical axis. Is made. However, as shown in FIG. 3, when a strong load is applied to the tip of the movable cylinder 11 from above, the movable cylinder 11 rotates counterclockwise around the cam follower 30 located on the upper side to the optical axis. Inclined posture. In this case, as shown in FIG. 4, the cam follower 30 located on the lower side once hits the play cam surface 37 of the first cam groove 31, and then gets over the play cam surface 37 and may come off from the first cam groove 31. There is. Therefore, as shown in FIG. 5, the first cam groove 31 of the present embodiment is formed such that the play cam surface 37 has a larger inclination angle than the cam surface 38. Regarding the cam follower 30, both opposing slopes having a trapezoidal cross section have substantially the same inclination angle as the cam surface 38.

  As shown in FIG. 6, the first and second cam grooves 31 and 32 connect a plurality of straight lines or straight lines and curves so as to continuously move the front and rear lens groups 17 and 18 in the optical axis direction. It is formed in a different shape. When the motor 19 is driven in the tele direction, the cam cylinder 13 rotates in the tele direction, and the first and second cam grooves 31 and 32 move the cam followers 29 and 30 from the retracted position shown in FIG. The cam followers 29 and 30 are respectively moved in the optical axis direction based on the displacement of the first and second cam grooves 31 and 32 in the optical axis direction. Since the cam followers 29 and 30 are urged toward the front of the optical axis by the spring 36, they do not come into contact with the play cam surfaces 37 and 40 when the cam cylinder 13 stops. Since the play cam surface 37 of the first cam groove 31 is formed with a large inclination angle with respect to the cam surface 38, the play cam made with the same inclination angle as the cam surface when the inner surface of the cam cylinder 13 is unfolded. In the first cam groove 31 of the present embodiment, the front end to the play cam surface 37 is wider than the front end (dotted line).

  The range in which the inclination angle is increased is the entire range of the first cam groove 31, but may be limited to a desired range instead. For example, it may be limited to a frequently used photographing area, that is, a range between the wide end and the tele end. Furthermore, normally, when the camera is turned on, the camera often waits at a wide position, for example, as a shooting standby position. Therefore, since an external force is often applied at the wide position, it may be limited to the front and rear ranges including the position where the cam follower 30 slides when the lens apparatus 10 is at the wide position.

  As a result, even if an external force is applied to the movable cylinder 11, since the play cam surface 37 in the direction in which the cam follower 30 is removed is a gentle slope, the contact force of the cam follower 30 on the play cam surface 37 becomes weak, and the play cam surface 37. It is possible to prevent the contact mark and the bite mark from being attached to the surface. Further, when an external force is applied, the opening of the first cam groove 31 is widened, so that it often remains on the play cam surface 37 even if the cam follower 30 moves away. In this case, when the cam barrel 13 is rotated next time, the cam follower 30 that has come off is pushed in by the play cam surface 37, so that it can be returned again to the position where it abuts on the cam surface 38.

[Second Embodiment]
As shown in FIG. 7, some cam cylinders are provided with a plurality of anti-reflection light shielding grooves 42 on the inner surface. The light shielding groove 42 has a generally uneven shape, for example, a cross-sectional thread shape. However, when the light shielding groove 42 is provided to the vicinity of the opening of the first cam groove 31, the cam follower 30 is caught by the light shielding groove 42 immediately after riding on the inner surface of the cam cylinder 13 from the first cam groove 31, and the first cam groove 31. Will prevent the return to. Further, since the light shielding groove 42 is formed next to the first cam groove 31, the thickness between the light shielding groove 42 and the first cam groove 31 is reduced, and the strength of the first cam groove 31 is reduced. For this reason, when the cam follower 30 comes into contact with the play cam surface 37, there is a possibility that a phenomenon of hitting the play cam surface 37 may occur. Therefore, as shown in FIG. 8, it is desirable to make the light shielding groove 42 apart from the first cam groove 31 by a predetermined length H. The predetermined length H is a length along the rear of the optical axis from the end of the first cam groove 31, that is, the play cam surface 37. As this length H, it is desirable to satisfy the conditional expression described in Equation 1.

  In the equation described in Equation 1, only one of the cam followers 30 provided at substantially three division positions in the circumferential direction is detached from the first cam groove 31, and the remaining two cam followers 30 are accommodated in the first cam groove 31. It is a conditional expression in the state of being. In this state, if the trajectory where the tip of the cam follower 30 moved away from the first cam groove 31 moves with respect to the cam follower 30 engaged with the first cam groove 31 is “R”, the trajectory R is the cam follower. The radius is 3/4 times the radius A up to 30 tips. From this locus R and the amount by which the cam follower 30 is engaged with the first cam groove 31, the extent to which the inner surface of the cam cylinder 13 is scraped by the cam follower 30 was calculated. In addition, the symbol B shown in FIG. 8B is a radius to the inner surface of the cam cylinder 13.

  As shown in FIG. 9, if the range from the first cam groove 31 to the light shielding groove 42 is a light shielding groove-less portion 44, the range where the light shielding groove-less portion 44 is provided is an imaging region, that is, a wide position and a tele position. It is desirable to make the light-shielding groove-less portion 44 only in the range of the first cam groove 31 used between the two. In many cameras, generally, when the power is turned on, the standby position becomes the wide position, and the camera stands by here. Therefore, as shown in FIG. 10, the light-shielding groove-less portion 44 may be formed only in the vicinity of the wide position. In this case, since the movable cylinder 11 protrudes toward the subject side, there is no problem even if the light shielding groove-less portion 44 is formed only in the vicinity of the wide position because the influence of internal reflection is small. In the case where there is an influence, it is desirable that the non-light-shielding groove-less portion 44 is subjected to a textured process that is fine unevenness. The first cam groove 31 used in this embodiment may be the cam groove described in the first embodiment or a general cam groove having a trapezoidal cross section.

[Third embodiment]
By the way, when the cam follower 30 is disengaged from the first cam groove 31 and rides on the inner surface of the cam cylinder 13, the cam follower 30 comes into pressure contact with the inner surface of the cam cylinder 13, so that a load is applied to the rotation of the cam cylinder 13. There is a possibility that inconvenience that the tube 13 does not rotate may occur. Therefore, the embodiment shown in FIG. 11 is an example in which the sub cam groove 46 is provided in the first cam groove 31 so that the cam follower 30 detached from the first cam groove 31 is automatically returned to the first cam groove 31 again. . In this embodiment, the sub cam groove 46 is provided in the vicinity of the position of the first cam groove 31 that slides when the cam follower 30 is in the wide position. The auxiliary cam groove 46 is provided at a predetermined distance from the play cam surface 37 at the rear of the optical axis, and both ends are connected to the first cam groove 31 before and after the position where the cam follower 30 slides in the wide position. Yes.

  The reason why the auxiliary cam groove 46 is provided in the vicinity of the wide position is that there are many cases in which the camera stands by at the wide position when the camera is turned on. Therefore, there is a high probability that a load is applied to the movable cylinder 11 at this wide position. As can be seen from the shape of the first cam groove 31, in the wide position, the movable cylinder 11 is the position that protrudes most forward of the optical axis from the cam cylinder 13, so that the movable cylinder 11 and the cam cylinder 13 overlap in the optical axis direction. The length of the front lens group 17 is reduced even when a rotational position error occurs in the cam cylinder 13 so that optical adjustment can be easily performed at the wide position in that the cam cylinder 13 supports the movable cylinder 11 with the smallest length. This is because the cam follower 30 slides when the wide position of the first cam groove 31 is the cam surface 38a parallel to the rotation direction of the cam cylinder 13 so that the position does not change. That.

  As shown in FIG. 12, when an external force is applied to the cam cylinder 13 in the direction of the arrow shown in FIG. 12A, the cam follower 30 gets over the first cam groove 31 as shown in FIG. Get on the inside. At this time, since the auxiliary cam groove 46 is formed next to the first cam groove 31, the cam follower 30 riding on the inner surface enters the auxiliary cam groove 46 as shown in FIG. Since the auxiliary cam groove 46 is connected to the first cam groove 31, the cam follower 30 returns to the first cam groove 31 by performing a return operation in which the cam cylinder 13 rotates toward the retracted position or the tele position.

  FIG. 13 is an example in which a sub cam groove 47 is provided in a range in which the cam follower 30 slides on the first cam groove 31 in the photographing region between the wide position and the tele position. Only one end of the sub cam groove 47 is connected to the first cam groove 31. The one end 47 a is an end in a direction to return the cam follower 30 to the first cam groove 31 when the cam cylinder 13 rotates toward the retracted position. Therefore, the returning operation in this case is an operation of rotating the cam cylinder 13 toward the retracted position. In general, in a zoom lens barrel, an origin sensor detects that a moving position of a moving cylinder or a cam cylinder has moved to a retracted position or a wide position. Therefore, it is preferable that the returning operation is an operation for once returning the lens device 10 to the wide position or the retracted position.

  At the time of the return operation, it is assumed that the cam follower 30 enters each of the remaining two first cam grooves 31 except for the first cam groove 31 from which the cam follower 30 has been removed. In this state, the cam follower 30 is disengaged from the first cam groove 31 and enters the sub cam groove 47 at one location, so that the movable cylinder 11 is inclined with respect to the optical axis. For this reason, during the returning operation, the cam follower 30 may move in the first two cam grooves 31 while abutting the idle cam surface 37 in the remaining two cam grooves 31 to apply a load to the rotation of the cam cylinder 13. Therefore, as described in the first embodiment, the cam groove in which the inclination angle of the play cam surface 37 is laid with respect to the cam surface 38 is used as the first cam groove 31 of this embodiment to reduce the load. Can do.

  The returning operation of the camera for returning the dropped cam follower 30 to the first cam groove 31 may be an operation for turning off the power of the camera, that is, an ending operation for retracting the lens device 10 to the retracted position. In this case, the retracted position is detected by the origin sensor. Further, in response to detecting an abnormality caused by the cam follower 30 dropping off from the first cam groove 31, a return operation is performed once to return to the original zoom position or the photographing preparation position (wide position) again. May be.

  FIG. 14 shows a camera 50 that detects an abnormality and performs a return operation. The camera 50 uses the lens device 10 described in FIG. The driving of the motor 19 is controlled by the CPU 52 via the driver 51. The drive of the motor 19 is transmitted to the rotary cylinder 16 via the gear train 53. A rotary encoder 54 is incorporated in the gear train 53. The rotary encoder 54 has a slit plate and a photoelectric conversion element, detects the rotation direction and rotation angle of the motor 19, and feeds it back to the CPU 52. The driver 51 can drive the motor 19 with high torque by increasing the drive voltage. The CPU 52 includes a timer circuit 52a and a count circuit 52b. After the motor 19 is driven, the timer circuit 52a measures a predetermined time, and the pulses obtained from the rotary encoder 54 are counted by the count circuit 52b. An abnormality check operation is performed to check whether there is an abnormality based on the value. Reference numeral 56 denotes an origin sensor that detects that the cam cylinder 13 has moved to the retracted position. When the wide position is detected by the origin sensor, the retracted position may be recognized by driving the motor 19 by a predetermined number of pulses after reaching the wide position.

  As shown in FIG. 15, the abnormality check operation is performed when the pulse signal is not obtained from the rotary encoder 54 while the timer circuit 52a measures time (when zoom driving is not performed), or when the count circuit 52b counts. This is a check operation in which when the value is smaller than a predetermined threshold value (when zoom driving is slow) or the like is determined as abnormal, and the others are determined as normal. As a result, a return operation is performed in the case of an abnormality.

  In the return operation, the motor 19 is driven by raising the drive voltage compared to the zoom drive. This driving direction is a direction in which the lens apparatus 10 is retracted toward the retracted position. During this time, the same abnormality check operation as described above is performed again, and if it is determined that there is an abnormality, zoom driving is not performed or slow even if the motor 19 is driven with high torque. It is determined that the damage to the groove 31 is so large that it is not preferable for use as a camera, and a warning is displayed on the display unit 57 provided outside. When it is determined that the abnormality check operation in the high torque drive is normal, the cam follower 30 returns from the sub cam groove 47 to the first cam groove 31 and the lens device 10 is moved into the retracted position as it is. By detecting the retracted position of the cam cylinder 13 by the origin sensor 56, the driving of the motor 19 is stopped. Thereafter, the motor 19 is driven with a normal driving voltage to move the lens apparatus 10 to the initial photographing state, for example, the wide position. The CPU 52 invalidates the release operation during the return operation.

  In the above-described embodiment, whether an abnormality is normal or not is determined based on a pulse signal obtained from driving the motor 19. However, an abnormality can also be determined by an AF circuit that is a contrast detection method. In the camera 60 of this example, an AF circuit 61 is built in a digital signal processing circuit 62 as shown in FIGS. An image signal obtained from the imaging sensor 35 is once taken into the frame memory 64 through the analog signal processing circuit 63 and the digital signal processing circuit 62 in this order. The AF circuit 61 detects the contrast based on the image signal read from the frame memory 64 and sends it to the CPU 65. In response to receiving the release signal from the operation unit 66, the CPU 65 drives the motor 19 to move the lens to the position where the contrast becomes the highest, and performs focusing.

  The AF circuit 61 checks the contrast in other areas in addition to the central area of the image so that the optimum focus can be obtained even when the subject is not in the center. For this reason, when the cam follower 30 is disengaged from the first cam groove 31 and enters the sub cam groove 47, the movable cylinder 11 is tilted, so that the imaging surface is tilted. However, it will be greatly blurred in other areas. In such a situation and when the shutter button is not half-pressed, the CPU 65 determines that there is an abnormality and executes the return operation. However, depending on the distance distribution of the subject, it may happen that only a specific area is in focus. In such a case, it is desirable to make a comprehensive determination from the zoom drive status and the focus status. As the determination of the zoom driving status, NG is determined when the driving time of the zoom is longer than a predetermined value, or NG when the driving current of the zoom motor is detected and exceeds the predetermined value. Alternatively, the zoom driving status may be determined based on both determinations. In the case of being based on both determinations, both may be NG.

  In the return operation, the motor 19 is driven by raising the drive voltage as compared with the zoom drive, as described with reference to FIG. During this time, the abnormality check operation is performed in the same manner as described with reference to FIG. 14, and when it is determined that there is an abnormality, a warning is displayed on the display unit 67. When it is determined that the abnormality check operation performed at the time of high torque driving is normal, the cam follower 30 returns from the sub cam groove 47 to the first cam groove 31 and the lens apparatus 10 is moved into the retracted position as it is. Thereafter, the motor 19 is driven with a normal driving voltage to move the lens apparatus 10 to the initial photographing state, for example, the wide position.

  Furthermore, as another example, an acceleration sensor, an impact sensor, or the like is built in the camera. As shown in FIG. 18, when the camera has an impact of a predetermined level or more, and the lens device 10 is in the shooting range (wide position). If it is located in the area between the tele position and the tele position, a return operation to return to the retracted position is performed. In this return operation as well, as described with reference to FIG. 14, the motor is driven with a drive voltage higher than that during zoom drive. During this return operation, the abnormality check operation is performed in the same manner as described with reference to FIG. 14, and when it is determined that there is an abnormality, a warning is displayed on the display unit. If it is determined that the abnormality check operation is normal, the cam follower returns from the auxiliary cam groove to the cam groove, and the lens barrel is moved into the retracted position as it is. Thereafter, the motor is driven with a normal driving voltage to move the lens barrel to the initial photographing state.

[Fourth Embodiment]
Incidentally, as shown in FIGS. 19 and 20A, the cam cylinder 13 is often provided with a reinforcing ring 70 at the tip. The reinforcing ring 70 is bonded to the end surface of the cam cylinder 13 on the subject side with an adhesive, and is fitted into a concave portion 71 having a substantially L-shaped cross section that connects the subject side end surface of the cam cylinder 13 and a part of the outer periphery thereof. It has a ring shape that fits together. The reinforcing ring 70 is for reinforcing the tip of the cam cylinder 13. In addition, since it is generally formed of a material such as aluminum or SUS, it has an effect of producing a high-class feeling when the entire lens barrel is viewed from the outside.

  However, when the cam follower 30 is disengaged from the first cam groove 31 and the movable cylinder 11 is inclined, as shown in FIG. 20B, one end 73 of the reinforcing ring 70 facing the movable cylinder 11 is at the movable cylinder 11. There is a possibility that a great load is applied to the rotation of the cam cylinder 13. Moreover, if the amount of biting is large, it is difficult to return to the cam groove 31 even if the cam groove 31 of the first embodiment is used, and the cam cylinder 13 provided with the auxiliary cam groove 47 for return is used. However, it is difficult to rotate the cam cylinder 13 even if the motor 19 is driven with high torque. Therefore, in this embodiment, as shown in FIG. 21, one end 75 facing the movable cylinder 11 in the L-shaped cross section of the reinforcing ring 74 is bent toward the image plane and the open side is used as the image plane. By adopting a reinforcing ring 74 that is formed in an annular shape with a U-shaped cross-section in a directed orientation and is rounded at a bent corner portion 76, the biting into the movable cylinder 11 is prevented.

  As another example, an elastic member 78 may be attached to the reinforcing ring 77 as shown in FIG. In this case, the reinforcing ring 77 has an L-shaped cross section and an annular shape, and the elastic member 78 has an annular shape that fits into one end 79 of the L-shaped cross section facing the movable cylinder 11. And is attached to the reinforcing ring 77 so as to be interposed between the one end 79 and the cam cylinder 13. As a result, the cam follower 30 is disengaged from the first cam groove 31 and the movable cylinder 11 is tilted. As shown in FIG. 23, the elastic member 78 is only elastically deformed even when the outer periphery of the movable cylinder 11 comes into contact. Therefore, it is possible to reliably prevent the reinforcing ring 77 from biting on the movable cylinder 11. Moreover, since the elastic member 78 has a large frictional resistance, it is possible to prevent the movable cylinder 11 from entering toward the image plane. The elastic member 78 is preferably made of a material such as rubber.

  In FIG. 22, the elastic member 78 has a substantially rectangular cross section, but the present invention is not limited to this, and as shown in FIG. 24, the elastic member 78 is provided with a light shielding rib 80 protruding toward the inner surface of the movable cylinder 11. The member 81 may be used. If the light shielding rib 80 is positively brought into contact with the outer periphery of the moving cylinder 11, it is possible to prevent dust and foreign matter from entering the lens device 10 through the gap between the moving cylinder 11 and the cam cylinder 13. it can. By the way, if the contact area of the light shielding rib 80 is large, a load is applied to the rotation of the cam cylinder 13. Therefore, as shown in FIG. 25, the load on the cam cylinder 13 can be reduced by using an elastic member 83 having a light shielding rib 82 made of a narrow cross-sectional shape with a sharp tip. In addition, as shown in FIG. 26, a light shielding effect can be obtained by using a plurality of, for example, two elastic members 86, which are provided with a plurality of, for example, two light shielding ribs 84, 85 formed in a narrow cross-sectional shape with a sharp tip. It can be further increased.

  In addition, as described with reference to FIG. 24, the elastic member is formed in a U-shaped cross-section with the opening side facing the one end 79 of the reinforcing ring 77. Therefore, when a plurality of light shielding ribs are provided, the elastic member 81 has one end. There is a risk that it will deviate from 79. Therefore, as shown in FIG. 27, the thickness of the part 86a of the elastic member 86 on the rear side of the optical axis with respect to the one end 79 is increased, and a plurality of light shielding ribs 87, 88 are provided on the subject side of the part 86a. This is desirable because it is difficult for the reinforcing ring 77 to come off. Furthermore, as shown in FIG. 28, when the one end 91 of the reinforcing ring 90 is bent toward the image plane, and the elastic member 92 is made in a cross-sectional shape that fits to the one end 91, it becomes more difficult to come off. Furthermore, in order to smoothly rotate the cam cylinder 13, a solid lubricant such as Teflon (registered trademark) such as fluororesin, molybdenum disulfide, or graphite is coated on the elastic member including the light shielding rib. Processing may be performed.

[Fifth Embodiment]
In this embodiment, when one of the three cam followers 30 is disengaged from the first cam groove 31 and the movable cylinder 11 is inclined, the corner inside the tip of the cam cylinder 13 bites into the outer periphery of the movable cylinder 11. 29, as shown in FIG. 29, a narrow recess 93 is provided in the outer periphery of the movable cylinder 11 along the circumferential direction, and the corner portion inside the tip of the cam cylinder 13 bites the outer periphery of the movable cylinder 11. This is an example of preventing sticking.

  As described with reference to FIG. 8, the recess 93 is provided in the vicinity of a position where the locus R having a radius that is 3/4 times the radius A to the tip of the cam follower 30 intersects the outer periphery of the movable cylinder 11. Good. The recess 93 may be U-shaped in cross section or V-shaped in cross section. In addition, as shown in FIG. 30, a plurality of recesses 95 may be provided side by side. Further, it is desirable that the concave portion 93 be provided at a position where the concave portion 93 interferes with the cam cylinder 13 at the wide position. According to this, even if the movable cylinder 11 is inclined, it is possible to prevent the corner portion inside the tip of the cam cylinder 13 from entering the concave portion 94 and to bite into the outer periphery of the movable barrel 11, and the corner portion is the concave portion 94. Therefore, it is possible to prevent the movable cylinder 11 from sliding into the cam cylinder 13.

  In each of the above embodiments, the cam follower is used, but a cam pin, a cam protrusion, or the like may be used. Moreover, although the other side is made into the cam groove, it is good also as a cam opening without a bottom. In each embodiment, a zoom lens barrel having two lens groups is described. However, the present invention is not limited to this, and a lens barrel having three or more lens groups may be used. Furthermore, although described as a step zoom using a single motor, a zoom lens mirror that uses a motor for zooming and focusing to change the driving of the motor during zooming and focusing respectively. It may be a cylinder. In this case, the zooming motor may be configured to be driven with high torque.

  The first to fifth embodiments described above may be used individually as the present invention. In addition, the first embodiment can be used by combining any one or more of the second to fifth embodiments, and the second embodiment is the third to fifth embodiment. Any one or more of these can be used in combination. Further, the third embodiment can be used by combining any one or both of the fourth and fifth embodiments, and the fourth embodiment is used by combining the fifth embodiment. be able to. In the second, fourth, and fifth embodiments, the biasing spring 36 can be omitted.

  The lens apparatus described in each of the above embodiments can be used not only for an electronic camera but also for a mobile phone with a camera, a video camera, and the like.

It is sectional drawing which shows the state of the retracted position of the lens barrel which employ | adopted this invention. It is sectional drawing which shows the state of the wide position of the lens-barrel demonstrated in FIG. It is sectional drawing which shows the state which the external cylinder applied and the movable cylinder inclined. It is principal part sectional drawing which shows the state from which the cam follower removed from the conventional 1st cam groove. It is principal part sectional drawing which shows the state from which the cam follower removed from the 1st cam groove of 1st Embodiment. It is an expanded view which shows the inner surface of a cam cylinder. It is sectional drawing which shows the cam cylinder which provided the light-shielding groove in the inner surface. 8A and 9B are explanatory views showing the relationship between the cam cylinder and the movable cylinder described in FIG. 7, where FIG. 7A is a cross-sectional view broken along the optical axis direction, and FIG. 8B is broken along a direction orthogonal to the optical axis. Each of the cross-sectional views is shown. FIG. 3 is a development view of a cam cylinder showing an embodiment in which a light shielding groove is eliminated only in a range corresponding to an imaging region. FIG. 10 is a development view of a cam cylinder showing another embodiment in which the light shielding groove is eliminated only in a range corresponding to the wide position. FIG. 5 is a development view of a cam cylinder showing an embodiment in which a sub cam groove for returning a cam follower that has been detached from the cam groove to the cam groove is provided only in a range corresponding to the wide position. (A) (B) (C) is explanatory drawing which shows a mode that the cam follower remove | deviated from the cam groove penetrates into a sub cam groove. FIG. 6 is a development view of a cam cylinder showing another embodiment in which a sub cam groove is provided in a range corresponding to an imaging region. FIG. 14 is a block diagram illustrating an electrical configuration of a camera that uses the lens barrel described in FIG. 13 and detects an abnormality in which the cam follower is disengaged from the cam groove based on a pulse signal corresponding to driving of the motor. It is a flowchart figure which shows the procedure of the return operation | movement which returns a cam follower to a cam groove with the camera demonstrated in FIG. FIG. 14 is a block diagram illustrating an electrical configuration of a camera that uses the lens barrel described in FIG. 13 and detects an abnormality in which the cam follower is disengaged from the cam groove using a contrast AF circuit. It is a flowchart figure which shows the procedure of the return operation | movement which returns a cam follower to a cam groove with the camera demonstrated in FIG. It is a flowchart figure which shows the procedure of the return operation | movement which returns a cam follower to a cam groove, when abnormality is detected with the camera which incorporated the impact sensor and the acceleration sensor. It is sectional drawing which shows the lens barrel which provided the reinforcement ring in the cam cylinder. It is principal part sectional drawing to which the range containing a reinforcement ring was expanded, (A) is sectional drawing of a normal state, (B) is sectional drawing of the state from which the cam follower removed from the cam groove. It is sectional drawing which shows the reinforcement ring of this embodiment. It is principal part sectional drawing which shows the example which attached the elastic member to the reinforcement ring, (A) is sectional drawing of both sides which pinched | interposed the optical axis, (B) is sectional drawing of only one which pinched | interposed the optical axis. It is principal part sectional drawing which shows the state which the movable cylinder inclined in the example demonstrated in FIG. It is principal part sectional drawing which shows the example which provided the light-shielding rib in the elastic member. It is sectional drawing which shows the elastic member which provided the narrow light-shielding rib of the pointed point. It is sectional drawing which shows the elastic member which provided the some light shielding rib. It is sectional drawing which shows the elastic member which thickened the thickness by the side of an optical axis so that it might not remove. It is principal part sectional drawing which shows the example which bent the front-end | tip of the reinforcement ring to the L shape so that it might not come out, and was engaged with the elastic member. It is sectional drawing which shows the lens apparatus which provided the small part in the outer periphery of a moving cylinder so that a moving cylinder may not incline and the inner corner | angular part of a cam cylinder may bite, (A) is sectional drawing fractured | ruptured along the optical axis direction, B) is a cross-sectional view taken along a direction orthogonal to the optical axis. FIG. 30 is a cross-sectional view showing a movable cylinder provided with a plurality of concave portions described in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Lens apparatus 11 Moving cylinder 13 Cam cylinder 14 Straight advance cylinder 15 Fixed cylinder 16 Rotation cylinder 20, 29, 30 Cam follower 21 Straight advance groove 22 Cam opening 31 1st cam groove 32 2nd cam groove 36 Spring for a side shift 37 Play cam surface 38 Cam surface 46, 47 Sub cam groove 50 Camera 70, 74, 77, 90 Reinforcement ring 78, 81, 86 Elastic member 80, 84, 87, 88 Light shielding rib

Claims (11)

A movable cylinder that holds a lens; and a cam cylinder that rotates with respect to the movable cylinder; a plurality of cam grooves provided at equally divided positions on the inner surface of the cam cylinder; and an equally divided position on the outer periphery of the movable cylinder In a lens barrel that engages with a plurality of cam followers provided on the lens barrel and rotates the cam cylinder in a state where the rotation of the movable cylinder is stopped to move the movable cylinder in the optical axis direction with respect to the cam cylinder. ,
Urging means for urging the cam follower toward the cam surface in front of the optical axis of the two cam surfaces constituting the cam groove;
A lens barrel characterized in that an inclination angle of the other play cam surface with respect to a surface perpendicular to the optical axis is made larger than a cam surface with which the cam follower abuts by urging of the urging means.   2. The lens barrel according to claim 1, wherein a light shielding groove for preventing internal reflection is provided on the inner surface of the cam barrel at a predetermined distance from the play cam surface toward the rear of the optical axis.   The auxiliary cam groove is provided with one end connected to the cam groove, and the remainder from the one end is provided at a predetermined distance from the play cam surface toward the rear of the optical axis, and the auxiliary cam groove is separated from the cam groove. 3. The lens barrel according to claim 1, wherein the cam follower is received and returned to the cam groove again.   Detecting means for detecting that the cam follower is disengaged from the cam groove and the moving cylinder is inclined with respect to the optical axis; and the cam follower is at least in response to detecting the inclination of the moving cylinder by the detecting means. 4. The lens barrel according to claim 3, further comprising return operation control means for rotating the cam cylinder to a position where the cam cylinder is returned to the cam groove beyond one end.   An impact detection means for detecting an external impact applied to the lens device; and a position at which the cam follower returns to the cam groove at least beyond the one end in response to the impact detection means detecting the impact. 4. The lens barrel according to claim 3, further comprising return operation control means for rotating the cam cylinder.   A reinforcing ring having an L-shaped cross section comprising an end that covers the front end of the optical axis of the cam cylinder and an other end that covers the cam cylinder and covers a part of the outer periphery of the cam cylinder is provided. 6. The lens barrel according to claim 1, wherein the lens barrel is bent toward the front.   An L-shaped reinforcing ring comprising one end covering the front end of the cam cylinder in front of the optical axis and the other end connected to the one end and covering a part of the outer periphery of the cam cylinder is provided, and an elastic member is provided at the one end The lens barrel according to any one of claims 1 to 6, wherein:   The lens barrel according to claim 7, wherein the elastic member is provided with a light-shielding rib that comes into contact with an outer surface of the movable barrel.   9. The lens barrel according to claim 8, wherein the light shielding rib is coated with a solid lubricant having a low frictional resistance.   A recess is provided in the outer periphery of the movable cylinder at a position in front of the optical axis with respect to the cam follower to prevent the inner corner of the front end of the optical axis of the cam cylinder from biting in when an external force is applied to the movable cylinder. The lens barrel according to claim 1, wherein the lens barrel is configured as described above.   The concave portion is provided in a range in which an inner corner portion of the cam barrel bites when the lens barrel is in a positional relationship between the movable barrel and the cam barrel when the lens barrel is at a photographing preparation position. The lens barrel according to claim 10.

Images