JP2012058459A - Lens barrel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely reduce sliding resistance.SOLUTION: A lens barrel 25 has first-third lens units 41-43, a fixed cylinder 44 and a cam cylinder 45. The first lens unit 41 has a first projection lens 11 and a lens frame 47. A roller 51 is attached to the lens frame 47 in a rotatable manner. A straight advance guide hole 44a in which the roller 51 fits is formed in the fixed cylinder 44, and first-third cam holes 45a-45c in which the roller 51 fits are formed in the cam cylinder 45. Grease 55 is applied to the straight advance guide hole 44a and the first-third cam holes 45a-45c. A grease reservoir concave part 44c is formed in the fixed cylinder 44, and a grease reservoir concave part 45d is formed in the cam cylinder 45. The grease 55 is applied to each of the grease reservoir concave parts 44c, 45d. The grease 55 is supplied to the straight advance guide hole 44a and to the first-third cam holes 45a-45c from each of the grease reservoir concave parts 44c, 45d.

Description

  The present invention relates to a lens barrel.

  A lens barrel used in various optical devices such as projectors and digital cameras is provided with a cam barrel for moving the lens in the optical axis direction and a fixed barrel that rotatably supports the cam barrel. The lens is held by a ring-shaped lens frame, and this lens frame is disposed inside the cam cylinder. An elongated cam hole is formed on the outer periphery of the cam cylinder, and a cam follower such as a roller or a shaft that engages with the cam hole is attached to the outer periphery of the lens frame. When the cam cylinder is rotated and the cam follower is moved along the cam hole, the lens frame moves in the optical axis direction, and the projection image and the captured image are zoomed by the movement of the lens frame.

  In order to make the movement of the lens frame in the direction of the optical axis smooth, there has been conventionally devised to reduce the sliding resistance between the cam follower and the cam hole. In Patent Document 1, a wide hole portion wider than the front and rear hole widths is formed in a part of the cam hole, and a lubricant for reducing sliding resistance between the cam follower and the cam hole is formed in the wide hole portion. By applying this grease, the lubricant is supplied over the entire length of the cam hole by the reciprocating motion of the cam follower.

Japanese Patent Laid-Open No. 7-014249

  In Patent Document 1, the lubricant applied to the wide hole portion is supplied over the entire length of the cam hole by the movement of the cam follower. However, when the cam follower is reciprocated repeatedly, the lubricant is pushed to the end of the cam hole. Therefore, only a small amount of lubricant remains in the wide hole portion and the sliding portion between the cam follower and the cam hole. The slight amount of lubricant remaining in the wide hole and sliding part also spreads to the peripheral part over time, and no lubricant remains in the wide hole and sliding part, so the sliding resistance between the cam follower and the cam hole Cannot be reduced. In addition, by adjusting the viscosity of the grease, which is a lubricant, even if the load during operation (operation torque) is adjusted to a desired value, if the lubricant does not remain in the wide hole portion or the sliding portion, Since the operating torque changes, the operability is poor.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a lens barrel that can reliably reduce sliding resistance.

  In order to solve the above problems, a lens barrel of the present invention has a lens frame that holds a lens, a cam follower provided in the lens frame, and a long-holed cam hole with which the cam follower is engaged. A cam cylinder that moves the lens frame in the optical axis direction by rotation; and a fixed cylinder that rotatably supports the cam cylinder, and the cam cylinder includes two cam wall surfaces facing each other that form the cam hole. At least one of the above is provided with a first reservoir recess for storing the lubricant. Examples of the lubricant include lubricating oil, grease, and solid lubricant.

  The cam follower is preferably a roller rotatably attached to the lens frame.

  Furthermore, it is preferable that the 1st accumulation recessed part is continuously formed over the perimeter of the said cam wall surface.

  The fixed cylinder is provided on the inner side of the cam cylinder, and the cam follower engages with the linear guide hole extending along the optical axis direction to guide the movement of the lens frame in the optical axis direction. Preferably, at least one of the two opposing guide wall surfaces constituting the straight guide hole is provided with a second reservoir recess for storing a lubricant.

  Furthermore, it is preferable that the second reservoir recess is formed continuously over the entire circumference of the guide wall surface.

  According to the present invention, the cam cylinder in which the cam hole with which the cam follower is engaged is provided with the first reservoir recess for storing the lubricant, so that the cam follower repeatedly moves in the cam hole and is originally applied in the cam hole. Even when the lubricant is pushed to the end of the cam hole, new lubricant is supplied into the cam hole from the first reservoir recess. Thereby, even when the cam cylinder is repeatedly rotated, the sliding resistance between the cam follower and the cam hole can be reliably reduced.

It is a perspective view which shows a projector. It is explanatory drawing which shows the schematic structure of a projector. It is a perspective view which shows a lens-barrel. It is a perspective view which shows a fixed cylinder. It is a perspective view which shows a cam cylinder. It is a perspective view which shows a 1st lens unit. It is front sectional drawing which shows the lens-barrel before roller attachment. It is front sectional drawing which shows the lens barrel after roller attachment. It is front sectional drawing which shows the principal part of a lens-barrel. It is side surface sectional drawing which shows the principal part of a lens-barrel. It is front sectional drawing which shows the principal part of the lens-barrel of embodiment which provided the taper-shaped grease accumulation recessed part in the fixed cylinder and the cam cylinder. It is front sectional drawing which shows the principal part of the lens barrel of embodiment which provided the grease storage recessed part in the intermediate part of the thickness direction of a fixed cylinder, and the intermediate part of the thickness direction of a cam cylinder. It is front sectional drawing which shows the principal part of the lens barrel of embodiment provided with the 1st-3rd roller.

  As shown in FIG. 1, when the projector 10 is used, the first projection lens 11 is exposed on the front surface of the case 14 by opening the lens cover. A second projection lens 12 and a third projection lens 13 are disposed behind the first projection lens 11 in the case 14. A screen 15 (see FIG. 2) is disposed in front of the first projection lens 11, and an image is projected from the first projection lens 11. A rotary zoom dial 16 is provided on the upper surface of the case 14, and the first to third projection lenses 11 to 13 are operated (rotated) in the A direction and the B direction in FIG. The zoom adjustment of the projected image (image projected on the screen 15) is performed.

  As shown in FIG. 2, a light source 21, an illumination optical system 22, a total reflection prism 23, a DMD 24, a lens barrel 25 that is a projection optical system, a zoom adjustment mechanism 26, and the like are provided inside the case 14. As the light source 21, for example, a white light source such as a xenon lamp or a mercury lamp is used. The illumination light emitted from the light source 21 enters the illumination optical system 22.

  The illumination optical system 22 includes a color wheel 31, a rod integrator 32, relay lenses 33 and 34, and a mirror 35. The color wheel 31 separates the illumination light from the light source 21 into B, G, and R colors in a time-sharing manner. The color wheel 31 has three color filters, a B filter that transmits only B light, a G filter that transmits only G light, and an R filter that transmits only R light, from the rotation center of the substrate. They are arranged at approximately the same distance. The color wheel 31 rotates at high speed and sequentially inserts the filters of each color into the illumination optical path. As a result, the illumination light is color-separated into three colors of B, G, and R in a time-sharing manner, and the separated light of each color is sequentially emitted toward the DMD 24.

  The rod integrator 32 is made of, for example, glass and has a reflection surface formed on the inner side. The light separated by the color wheel 31 is homogenized by repeating reflection while passing through the rod integrator 32. The relay lenses 33 and 34 relay the light beam emitted from the rod integrator 32 to the mirror 35. The mirror 35 reflects this light beam toward the total reflection prism 23.

  The total reflection prism 23 is composed of two triangular prisms, and an air gap is provided between the two triangular prisms to form the reflection surface 23a. The incident light incident on the total reflection prism 23 from the mirror 35 has a larger incident angle than the critical angle, and therefore is totally reflected by the reflection surface 23a and incident on the DMD 24. On the other hand, the reflected light reflected by the DMD 24 is transmitted through the reflecting surface 23a because the incident angle is smaller than the critical angle.

  As is well known, the DMD 24 has a large number of mirror elements corresponding to pixels arranged in a matrix on the light receiving surface. Each mirror element changes the reflection direction of the received illumination light by changing the angle based on the projected image. When displaying a pixel brightly, the mirror element is displaced to the ON position, and the received light is reflected toward the lens barrel 25 as ON light. On the other hand, when a pixel is displayed darkly, the mirror element is displaced to the off position, and the received light is reflected as off light in a direction away from the lens barrel 25. The image light is constituted by a set of on-lights toward the lens barrel 25.

  As shown in FIGS. 2 to 10, the lens barrel 25 is disposed outside the first to third lens units 41 to 43, the fixed tube 44, and the fixed tube 44, and is rotatable by the fixed tube 44. And a cam cylinder 45 to be supported. The cam cylinder 45 is covered with a cover cylinder (not shown).

  The image light generated by the DMD 24 is imaged on the screen 15 by the first to third lens units 41 to 43 of the lens barrel 25, and the image is projected on the screen 15.

  The first lens unit 41 includes a first projection lens 11 and a lens frame 47 that holds the first projection lens 11.

  Three roller mounting portions 47 a are formed on the outer peripheral surface of the lens frame 47 at a 120 ° pitch. A roller 51 is rotatably attached to each of these three roller attachment portions 47a by attachment pins 52. An insertion recess 47b into which the end of the roller 51 is inserted is formed in the roller mounting portion 47a.

  The mounting pin 52 includes a head portion 52a, a shaft portion 52b, and a screw portion 52c threaded with a diameter smaller than that of the shaft portion 52b. The screw portion 52 c is screwed into a screw hole 47 c formed in the roller attachment portion 47 a, the shaft portion 52 b is inserted through the insertion hole 51 a formed in the roller 51, and the head portion 52 a is formed in the roller 51. It is stored in the storage recess 51b.

  Similarly to the first lens unit 41, the second lens unit 42 includes the second projection lens 12 and the lens frame 47, and the third lens unit 43 includes the third projection lens 13 and the lens frame 47. Three rollers 51 are rotatably attached to each lens frame 47.

  Each roller 51 of each lens unit 41-43 is inserted in the outer peripheral surface of the fixed cylinder 44, and is a linear guide extending along the optical axis direction so as to guide the movement of each lens unit 41-43 in the optical axis direction. A hole 44a is formed. Three straight guide holes 44a are formed at a pitch of 120 °. A flange portion 44 b is formed at the rear end portion of the fixed cylinder 44, and the flange portion 44 b is fixed to the case 14 of the projector 10. Further, a support portion (not shown) that rotatably supports the cam cylinder 45 is provided on the outer peripheral surface of the fixed cylinder 44.

  Grease 55 for reducing sliding resistance between the roller 51 and the rectilinear guide hole 44a is applied to the rectilinear guide hole 44a of the fixed cylinder 44. Further, on the outer peripheral surface of the fixed cylinder 44, a grease reservoir recess 44c for storing the grease 55 is formed continuously with the guide wall surface constituting the rectilinear guide hole 44a. The grease reservoir recess 44c is formed over the entire circumference of the guide wall surface. An appropriate amount of grease 55 is applied in advance to the grease reservoir recess 44c. The grease reservoir recess 44 c is preferably formed with a depth of 1 mm or more, or a depth of 1/4 or more of the thickness of the fixed cylinder 44. In this embodiment, the grease reservoir recess 44 c is formed of the fixed cylinder 44. For example, it is formed at a depth of 1/3 of the thickness.

  On the outer peripheral surface of the cam cylinder 45, first to third cam holes 45a to 45c having long holes through which the rollers 51 of the lens units 41 to 43 are inserted are formed. Three each of the first to third cam holes 45a to 45c is formed at a pitch of 120 °.

  Grease 55 for reducing the sliding resistance between the roller 51 and the first to third cam holes 45a to 45c is applied to the first to third cam holes 45a to 45c of the cam cylinder 45. Further, on the outer peripheral surface of the cam cylinder 45, a grease reservoir recess 45d for storing the grease 55 is formed continuously with the cam wall surfaces constituting the first to third cam holes 45a to 45c. The grease reservoir recess 45d is formed over the entire circumference of the cam wall surface. An appropriate amount of grease 55 is applied in advance to the grease reservoir recess 45d. The grease reservoir recess 45d is preferably formed with a depth of 1 mm or more or a depth of 1/4 or more of the thickness of the cam cylinder 45. In this embodiment, the grease reservoir recess 45d is formed on the cam cylinder 45. For example, the thickness is 2/5.

  The zoom adjustment mechanism 26 performs zoom adjustment of the projected image (image to be projected on the screen 15) by rotating the cam cylinder 45 in accordance with the rotation (operation) of the rotary zoom dial 16.

  Next, the operation of the above embodiment will be described. Illumination light emitted from the light source 21 enters the color wheel 31. The illumination light incident on the color wheel 31 is color-separated into three colors B, G, and R by time division by the color wheel 31.

  The light separated by the color wheel 31 is homogenized by repeating reflection while passing through the rod integrator 32. The light beam emitted from the rod integrator 32 is relayed to the mirror 35 by the relay lenses 33 and 34, and this light beam is reflected by the mirror 35 toward the total reflection prism 23.

  The incident light reflected by the mirror 35 and incident on the total reflection prism 23 is incident on the DMD 24 after being totally reflected by the reflection surface 23a because the incident angle is larger than the critical angle.

  The DMD 24 changes the reflection direction of the received illumination light by changing the angles of a large number of mirror elements arranged in a matrix on the light receiving surface based on the projected image. The image light generated by the DMD 24 is incident on the lens barrel 25 through the reflecting surface 23 a because the incident angle is smaller than the critical angle.

  The image light incident on the lens barrel 25 passes through the third projection lens 13, the second projection lens 12, and the first projection lens 11 and is imaged on the screen 15. As a result, an image is projected on the screen 15.

  When the zoom dial 16 is rotated (operated), the zoom adjustment mechanism 26 rotates the cam cylinder 45 in accordance with the rotation angle (operation amount) of the rotary zoom dial 16.

  When the cam cylinder 45 is rotated, the rollers 51 of the lens units 41 to 43 move along the first to third cam holes 45a to 45c while rotating, so that the lens units 41 to 43 are in the optical axis direction. Move to. At this time, since the roller 51 moves along the rectilinear guide hole 44a of the fixed cylinder 44, the lens units 41 to 43 move in the optical axis direction without rotating. The zoom adjustment of the projected image (image projected on the screen 15) is performed by the movement of the first to third lens units 41 to 43. In the present embodiment, the first and second lens units 41 and 42 are moved rearward (direction D in FIG. 3) by the rotation of the cam cylinder 45 in the clockwise direction, and the third lens unit 43 is moved forward (in FIG. 3). (C direction). Further, the rotation of the cam cylinder 45 in the counterclockwise direction causes the first and second lens units 41 and 42 to move forward and the third lens unit 43 to move backward.

  The grease 55 applied to the rectilinear guide hole 44a is pushed to the front end and the rear end of the rectilinear guide hole 44a by the movement of the rollers 51 of the lens units 41 to 43, but the grease 55 accumulated in the grease reservoir recess 44c. However, since it is newly supplied to the rectilinear guide hole 44a, the sliding resistance between each roller 51 and the rectilinear guide hole 44a is kept constant without increasing.

  Similarly, the grease 55 applied to the first to third cam holes 45a to 45c by the movement of the rollers 51 of the lens units 41 to 43 causes the left and right sides of the first to third cam holes 45a to 45c. The grease 55 accumulated in the grease reservoir recess 45d is newly supplied to the first to third cam holes 45a to 45c even when the roller 51 and the first to third cam holes 45a are pushed. The sliding resistance with .about.45c is kept constant without increasing.

  Further, as shown in FIG. 11, instead of the grease reservoir recess 44c and the grease reservoir recess 45d, a fixed cylinder 61 and a cam cylinder 62 provided with a tapered grease reservoir recess 61a and a grease reservoir recess 62a may be used. The fixed cylinder 61 and the cam cylinder 62 are configured in the same manner as the fixed cylinder 44 and the cam cylinder 45 except for the recesses 61a and 62a. The recesses 61 a and 62 a are preferably formed with chamfering: C1 (mm) or more, or a C (chamfering) dimension that is 1/4 or more of the thickness of the fixed cylinder 44.

  Furthermore, as shown in FIG. 12, instead of the grease reservoir recess 44c and the grease reservoir recess 45d, a fixed cylinder 71 and a cam cylinder 72 provided with a grease reservoir recess 71a and a grease reservoir recess 72a in the middle in the thickness direction are used. Also good. The fixed cylinder 71 and the cam cylinder 72 are configured in the same manner as the fixed cylinder 44 and the cam cylinder 45 except for the recesses 71a and 72a.

  Further, as shown in FIG. 13, first to third rollers 81 to 83 may be used instead of the rollers 51. The second and third rollers 82 and 83 are rotatably attached to the first roller 81. The first and second rollers 81 and 82 are engaged with the rectilinear guide hole 44 a of the fixed cylinder 44, and the third roller 83 is engaged with the first to third cam holes 45 a to 45 c of the cam cylinder 45. Furthermore, you may use the 1st-3rd rollers 81-83 for embodiment shown in FIG.11 and FIG.12.

  In the above embodiment, the roller rotatably attached to the lens frame is engaged with the straight guide hole of the fixed cylinder and the cam hole of the cam cylinder. However, the shaft fixed to the lens frame is linearly moved. You may engage with a guide hole and a cam hole.

  Moreover, in the said embodiment, although the grease accumulation recessed part is formed in both the wall surfaces of a rectilinear guide hole and a cam hole, what is necessary is just to form in at least one.

  Furthermore, in the above embodiment, the grease reservoir recess is formed over the entire circumference of the linear guide hole and the cam hole. However, it may be formed at least in the sliding range of the roller, and is not continuous, A plurality of grease reservoir recesses may be formed with a gap.

  In the above embodiment, the cam cylinder is arranged outside the fixed cylinder, but the cam cylinder may be arranged inside the fixed cylinder.

  Moreover, although the projector has been described in the above embodiment, the present invention can also be applied to a digital camera or a film camera.

DESCRIPTION OF SYMBOLS 10 Projector 11-13 1st-3rd projection lens 25 Lens barrel 41-43 1st-3rd lens unit 44 Fixed cylinder 44a Straight advance guide hole 44c Grease accumulation recessed part 45 Cam cylinder 45a-45c 1st-3rd cam hole 45d Grease accumulation recess 47 Lens frame 51 Roller

Claims (5)

A lens frame for holding the lens;
A cam follower provided in the lens frame;
A cam cylinder having an elongated cam hole with which the cam follower is engaged, and moving the lens frame in the optical axis direction by rotation;
A fixed cylinder that rotatably supports the cam cylinder,
The lens barrel, wherein the cam barrel is provided with a first reservoir recess for storing a lubricant on at least one of two opposing cam wall surfaces constituting the cam hole.   The lens barrel according to claim 1, wherein the cam follower is a roller rotatably attached to the lens frame.   3. The lens barrel according to claim 1, wherein the first reservoir recess is formed continuously over the entire circumference of the cam wall surface. 4.   The fixed cylinder is provided inside the cam cylinder, and the cam follower is engaged with the rectilinear guide hole extending along the optical axis direction so as to guide the movement of the lens frame in the optical axis direction. The lens barrel according to any one of claims 1 to 3, wherein a second reservoir recess for storing a lubricant is provided on at least one of the two opposing guide wall surfaces constituting the rectilinear guide hole. .   The lens barrel according to claim 4, wherein the second reservoir recess is formed continuously over the entire circumference of the guide wall surface.

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