JP2012185256A - Projection lens and projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection lens capable of suppressing a standing angle (an angle formed by the direction of a cam groove and a direction perpendicular to an optical axis) from being larger, even when the magnification of the projection lens is higher and to provide a projector.SOLUTION: A projection lens 5 includes a plurality of lens groups having a cam pin in a circumference, a guide barrel 52 which has a straightly advancing groove 524 formed along an optical axis C and passing through, in which the cam pin is engaged with the straightly advancing groove 524 and by which the plurality of lens groups are arranged in order and guided, and a cam barrel 53 which has a plurality of cam grooves 71 to 74 which are formed with a predetermined path, according to the plurality of lens groups and with which the cam pin is engaged in an inner circumferential surface, into which the guide barrel 52 is inserted and fitted, and which is rotated with respect to the guide barrel 52 in a circumferential direction to move the plurality of lens grooves along the optical axis C. The outer circumferential surface of the guide barrel 52 and the inner circumferential surface of the cam barrel 53 have engagement parts (screw parts for zooming 10 and 30, etc.) engaged with each other and the cam barrel 53 is rotated with respect to the guide barrel 52 in the circumferential surface to be moved along the optical axis C.

Description

  The present invention relates to a projection lens having a plurality of lenses and a projector provided with the projection lens.

  2. Description of the Related Art Conventionally, there is known a projector that modulates a light beam emitted from a light source according to image information to form image light, and enlarges and projects the image light using a projection lens. In general, a projection lens used in a projector has a guide cylinder in which a plurality of lenses are sequentially arranged linearly along an optical axis so as to be guided in a linear manner, and a plurality of lenses are inserted along the optical axis by inserting the guide cylinder. And a cam cylinder to be moved. Specifically, a cam groove is formed in the inner surface of the cam cylinder in the circumferential direction, and pins installed on the outer surfaces of a plurality of lenses guided linearly by the guide cylinder are engaged with the cam groove. Here, by rotating the cam cylinder in the circumferential direction of the guide cylinder, the pins installed on the outer surface of the lens move along the cam groove, so that the plurality of lenses can move in a predetermined manner along the optical axis. Each move in positional relationship. Thereby, zoom adjustment can be performed.

  In the lens barrel (projection lens) for the projector device described in Patent Document 1, it is disclosed that the same guide cylinder and cam cylinder as described above are formed of synthetic resin. Thereby, the guide cylinder and the cam cylinder can be easily manufactured by injection molding, and the manufacturing cost can be suppressed.

JP 2004-347646 A

However, when zoom adjustment is performed using a high-magnification projection lens, the amount of movement of the plurality of lenses increases. When the rotation angle of the cam barrel is set to a normal angle of 60 degrees or less, the angle formed between the cam groove direction and the direction perpendicular to the optical axis (hereinafter referred to as a standing angle) is large. Become. By increasing the standing angle, the gap in the optical axis direction between the pin and the cam groove is increased. When the gap in the optical axis direction increases, the lens tilts with respect to the optical axis as the pin rattles in the gap with the cam groove. When the lens is tilted with respect to the optical axis, there is a problem that it becomes very difficult to obtain the optical performance of the projection lens. Further, when the standing angle is increased, the torque for rotating the cam cylinder in the circumferential direction of the guide cylinder increases, and there is a problem that the feeling of operation of the zoom adjustment lever installed on the cam cylinder is deteriorated.
Therefore, there has been a demand for a projection lens and a projector that can suppress an increase in the standing angle even when the magnification of the projection lens is increased.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 A projection lens according to this application example includes a plurality of lenses fixed to a lens frame having a cam pin on the outer periphery, and a rectilinear groove that is formed along the optical axis of the projection lens and passes therethrough. A guide cylinder for engaging a cam pin with the groove and sequentially arranging and guiding a plurality of lenses, and a plurality of cams formed on the inner peripheral surface in a predetermined path corresponding to the plurality of lenses and engaging the cam pins A cam cylinder having a groove, a guide cylinder inserted therein, and a plurality of lenses moving along the optical axis by rotating in the circumferential direction with respect to the guide cylinder, and an outer peripheral surface of the guide cylinder and the cam cylinder And the cam barrel moves along the optical axis by rotation.

  According to this configuration, since the cam cylinder and the guide cylinder have the engaging portions, the cam cylinder is rotated in the circumferential direction of the guide cylinder, and the cam cylinder is moved along the optical axis, so that a plurality of lenses is provided. The movement angle of the plurality of lenses along the optical axis of the plurality of lenses can be secured by suppressing the increase in the standing angle of the cam groove. Therefore, even with a high-magnification projection lens, an increase in the standing angle can be suppressed, and zoom adjustment can be performed to achieve a desired magnification. Moreover, since it is possible to suppress an increase in the standing angle, it is possible to reduce the torque for rotating the cam cylinder in the circumferential direction of the guide cylinder, and to smoothly rotate the cam cylinder. In addition, since an increase in the standing angle can be suppressed, the gap in the optical axis direction between the cam pin and the cam groove can be reduced, and rattling in the cam groove of the cam pin can be suppressed. It is possible to suppress tilting with respect to the axis. Therefore, the optical performance of the projection lens can be ensured.

  Application Example 2 In the projection lens according to the application example described above, it is preferable that the engaging portion is constituted by a screw portion.

  According to this configuration, since the engaging portion is configured by the screw portion, the configuration in which the cam cylinder is moved along the optical axis is easily realized by engaging the screw portion.

  Application Example 3 In the projection lens according to the application example described above, it is preferable that the screw portion is formed of a helicoid screw.

  According to this configuration, since the screw portion is composed of a helicoid screw, when performing zoom adjustment so as to achieve a desired zoom, the optical axis direction of the cam cylinder is larger than that of a normal screw (single thread). The travel distance to can be shortened. Therefore, the length in the optical axis direction can be suppressed even with a high magnification projection lens, and the projection lens can be miniaturized.

  Application Example 4 In the projection lens according to the application example described above, the engaging portion includes a cam pin on one of the guide tube and the cam tube and a cam groove that engages with the cam pin on the other. Preferably it is.

  According to this configuration, since the engaging portion is configured by the cam pin and the cam groove, a configuration in which the cam cylinder is moved along the optical axis can be easily realized.

  Application Example 5 A projector according to this application example includes a light source, a light modulation device that modulates a light beam emitted from the light source based on image information to form image light, and any of the above-described projectors that project image light. And a projection lens.

  According to such a projector, by providing a projection lens that can suppress an increase in the standing angle, the length of the projection lens in the optical axis direction can be made compact even when a high-magnification projection lens is used. A projector that can smoothly adjust to zoom and improve the quality of image light to be projected is realized.

1 is a schematic diagram illustrating a schematic configuration of a projector according to a first embodiment. The perspective view of a projection lens. FIG. 3 is a schematic sectional view of a projection lens. The exploded perspective view of a projection lens. The disassembled perspective view of a lens frame unit. The perspective view of a guide cylinder. The perspective view of a cam cylinder. The expanded view of the inner surface side of a cam cylinder. FIG. 6 is a schematic sectional view of a projection lens according to a second embodiment.

Hereinafter, embodiments will be described with reference to the drawings.
(First embodiment)

  FIG. 1 is a schematic diagram illustrating a schematic configuration of a projector 1 according to the first embodiment. With reference to FIG. 1, the general configuration and operation of the projector 1 of the present embodiment will be briefly described.

  The projector 1 of the present embodiment modulates the light beam emitted from the light source 211 according to image information to form image light, and enlarges and projects this image light on a screen or the like. As shown in FIG. 1, the projector 1 supplies power to an optical unit 2 configured in a substantially L shape, an exterior casing 3 that houses each device and constitutes an exterior, a control unit (not shown), a control unit, and the like. A power supply device to be supplied (not shown) and a cooling mechanism (not shown) including a cooling fan for cooling the inside of the projector 1 are provided.

  The control unit includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, and functions as a computer, and is related to control of the operation of the projector 1, for example, image projection. Control and so on.

  As shown in FIG. 1, the optical unit 2 is a unit that forms and projects image light corresponding to image information by optically processing the light beam emitted from the light source 211 based on control by the control unit. The optical unit 2 accommodates the light source device 21, the illumination optical device 22, the color separation optical device 23, the relay optical device 24, the electro-optical device 25, and these optical devices 21 to 25, and the projection lens 5 at a predetermined position. The optical component housing 4 that is supported and fixed by is provided.

  The light source device 21 includes a light source 211, a reflector 212, and the like. The light source device 21 aligns the emission direction of the light beam emitted from the light source 211 by the reflector 212, makes it parallel to the optical axis C, and emits it toward the illumination optical device 22. The light source device 21 of the present embodiment employs an ultra high pressure mercury lamp.

  The illumination optical device 22 includes a first lens array 221, a second lens array 222, a polarization conversion element 223, a superimposing lens 224, and three field lenses 225. The first lens array 221 and the second lens array 222 decompose the light beam emitted from the light source device 21 into a plurality of partial light beams. The polarization conversion element 223 converts the partial light flux, which is random polarized light emitted from the second lens array 222, into substantially one type of polarized light that can be used in the liquid crystal panel 253, which will be described later, in order to increase the light use efficiency. Align. The superimposing lens 224, together with the field lens 225, converts each partial light beam emitted from the polarization conversion element 223 into a light beam parallel to its central axis (principal light beam), and superimposes it on the image forming area of the liquid crystal panel 253. Let

  The color separation optical device 23 includes two dichroic mirrors 231 and 232 and a reflection mirror 233. The light emitted from the illumination optical device 22 is converted into red (R) light, green (G) light, and blue (B) light. It has a function of separating into three color lights.

  The relay optical device 24 includes an incident side lens 241, a relay lens 243, and reflection mirrors 242, 244, and has a function of guiding the B light separated by the color separation optical device 23 to the B light liquid crystal panel 253B. The optical unit 2 has a configuration in which the relay optical device 24 guides the B light. However, the configuration is not limited thereto, and for example, the optical unit 2 may have a configuration that guides the R light.

  The electro-optical device 25 includes an incident-side polarizing plate 251 and three liquid crystal panels 253 as light modulators (the liquid crystal panel for R light is 253R, the liquid crystal panel for G light is 253G, and the liquid crystal panel for B light is 253B. ), An exit side polarizing plate 254, and a cross dichroic prism 255 as a color synthesizing optical device. The electro-optical device 25 modulates each color light separated by the color separation optical device 23 by each liquid crystal panel 253 in accordance with image information, and synthesizes the image light by combining the light beams modulated for each color light by the cross dichroic prism 255. Formed and emitted toward the projection lens 5.

  The projection lens 5 includes a plurality of lens groups each having one or a plurality of lenses as one lens group, and these lens groups are arranged along the optical axis C. The projection lens 5 has a zoom adjustment function and a focus adjustment function for incident image light, and enlarges and projects the image light formed by the electro-optical device 25 onto a screen (not shown).

  FIG. 2 is a perspective view of the projection lens 5. FIG. 3 is a schematic sectional view of the projection lens 5. The projection lens 5 will be described in detail with reference to FIGS. The incident side on which the image light is incident on the projection lens 5 is appropriately used as the rear side, and the projection side on which the image light is projected from the projection lens 5 is appropriately used as the front side. FIG. 2 is a view of the projection lens 5 as viewed from the front side. FIG. 3 shows a position (wide end) in which the later-described second lens group 82 to sixth lens group 86 are most retracted, with the optical axis C as the center, and the second lens group 82 on the lower side. To the sixth lens group 86 is shown at the most extended position (tele end).

  As shown in FIGS. 2 and 3, the projection lens 5 is arranged in order from the front side along the flange 51 arranged on the incident side, the guide tube 52, the cam tube 53, the front tube 54, and the optical axis C. The first lens group 81 to the seventh lens group 87 are provided. The projection lens 5 optically processes the image light incident from the seventh lens group 87 and then exits from the first lens group 81.

  The flange 51 has a rectangular outer shape in plan view, and a seventh lens group 87 is fixedly arranged at the center, and round holes 511 through which screws are inserted are formed at the four corners. The projection lens 5 is attached to the optical component housing 4 by fixing the flange 51 with screws.

  As shown in FIG. 3, the guide cylinder 52 has a shape in which a large cylindrical portion 521 having a large diameter and a small cylindrical portion 522 having a small diameter are coupled to each other at the end portions, and the large cylindrical portion 521 is connected to the front side. It is comprised so that it may become. The guide tube 52 is formed with a rectilinear groove 524 cut out along the direction of the optical axis C from the stepped portion formed by the large cylindrical portion 521 and the small cylindrical portion 522 toward the rear side. The guide tube 52 has a flange 51 screwed to the rear end portion of the small cylindrical portion 522.

  The guide tube 52 has a focus screw portion 523 formed on the outer peripheral surface of the large cylindrical portion 521. The guide cylinder 52 has a zoom screw portion 10 (screw portion) as an engaging portion formed on the outer peripheral surface in the vicinity of the step portion of the small cylindrical portion 522.

  The cam cylinder 53 is formed in a cylindrical shape, and a guide cylinder 52 is inserted inside the cam cylinder 53 so that the cam cylinder 53 can rotate about the optical axis C with respect to the guide cylinder 52. Cam grooves 71, 72, 73, 74 that define the movement operation of the second lens group 82 to the sixth lens group 86 are formed on the inner peripheral surface of the cam cylinder 53 along a predetermined path. Also, a zoom screw portion 30 (screw portion) as an engagement portion is formed on the inner peripheral surface of the front end portion of the cam cylinder 53, and is engaged (screwed) with the zoom screw portion 10 of the guide cylinder 52. And attached to the guide tube 52.

  The front cylinder 54 is formed in a cylindrical shape, and a first lens group 81 for focus adjustment is fixedly disposed. The front tube 54 has a focus screw portion 541 formed on the inner peripheral surface thereof, and is attached to the guide tube 52 by screwing with the focus screw portion 523 of the guide tube 52. The first lens group 81 is configured to move along the direction of the optical axis C as the front tube 54 rotates about the optical axis C.

  As described above, the first lens group 81 is fixedly disposed on the front tube 54, and the seventh lens group 87 is fixedly disposed on the flange 51. The second lens group 82 to the sixth lens group 86 are respectively held by five lens frames 61, 62, 63, 64, and 65, which will be described later, and are inserted into the small cylindrical portion 522 of the guide cylinder 52, and are attached to the optical axis C. It is configured to be movable along. Although details will be described later, cam pins 612, 622, 632, and 642 are formed on the lens frames 61, 62, 63, and 64, and the cam pins 612, 622, 632, and 642 serve as the rectilinear grooves 524 and the cam grooves 71, 72, 73, 74 are engaged.

Each of the lens frames 61, 62, 63, 64, 65 has the cam pins 612, 622, 632, 642 at the intersections of the rectilinear groove 524 and the cam grooves 71, 72, 73, 74 as the cam cylinder 53 rotates. By being guided, it moves in the direction of the optical axis C. At this time, the zoom cylinder 30 of the cam cylinder 53 is engaged with the zoom thread 10 of the guide cylinder 52 and is rotated to move the cam cylinder 53 in the direction of the optical axis C. The movement of 61, 62, 63, 64, 65 is assisted.
The projection lens 5 performs zoom adjustment and focus adjustment of the image light as these lens groups move.

  Note that the projection lens 5 of the present embodiment is configured such that the cam cylinder 53 and the front cylinder 54 are manually rotated. The cam cylinder 53 is provided with a zoom ring (not shown) corresponding to a zoom adjustment lever. The cam cylinder 53 is rotated by operating this zoom ring. In the following description, for the sake of convenience, the clockwise direction as viewed from the front side is referred to as “right direction” and the counterclockwise direction as “left direction” as appropriate for the rotation direction.

  FIG. 4 is an exploded perspective view of the projection lens 5. FIG. 4 is a view of the projection lens 5 as viewed from the front side. In FIG. 4, the flange 51 and the front cylinder 54 are omitted. The five lens frames 61, 62, 63, 64, 65, the guide tube 52, and the cam tube 53 will be described in detail with reference to FIG.

  As shown in FIG. 4, the five lens frames are arranged in the order of lens frames 61, 62, 63, 64, 65 from the front side, and the lens frames 63, 64, 65 are configured as a lens frame unit 60.

  The lens frame 61 is made of a synthetic resin such as PC (polycarbonate), and includes a holding portion 611 that holds the second lens group 82 and a cam pin 612 as shown in FIGS. 3 and 4. The holding part 611 is formed in an annular shape so as to cover the outer periphery of the second lens group 82, and the thickness in the radial direction around the optical axis C is set to a thickness that stably holds the second lens group 82. Has been.

  The cam pins 612 are formed so as to protrude from the outer peripheral surface of the holding portion 611 in a direction intersecting the optical axis C, and three cam pins 612 are provided at equal intervals of 120 ° in the circumferential direction around the optical axis C. The cam pin 612 is formed in a columnar shape, and the tip has a tapered shape with a narrow end.

  The three cam pins 612 are set to the same length. As shown in FIG. 4, the outer diameter dimension D1 of the lens frame 61 including the three cam pins 612 is the outer diameter dimension of the small cylindrical portion 522 of the guide cylinder 52. It is set larger. In other words, the length of the cam pin 612 is set so that the tip protrudes from the rectilinear groove 524 when the lens frame 61 is inserted into the guide tube 52, as shown in FIG.

  The lens frame 62 is made of a synthetic resin such as PC (polycarbonate), and has an annular holding portion 621 and three cam pins 622, similarly to the lens frame 61. A third lens group 83 is attached to the inner surface of the holding portion 621 by being sandwiched between an edge portion of the holding portion 621 and a metal plate (not shown). The holding part 621 has the same outer diameter as that of the holding part 611. The cam pin 622 is formed in the same shape as the cam pin 612, and is set so that the tip protrudes from the rectilinear groove 524 in the same manner as the cam pin 612 when the lens frame 62 is inserted into the guide tube 52.

  FIG. 5 is an exploded perspective view of the lens frame unit 60. FIG. 5 is a view of the lens frame unit 60 as viewed from the front side. The configuration of the lens frame unit 60 will be described with reference to FIGS.

  As described above, the lens frame unit 60 includes the lens frames 63, 64, and 65. The lens frames 63, 64, and 65 are made of a synthetic resin such as PC (polycarbonate). Similar to the lens frame 61, the lens frame 63 includes an annular holding portion 631 and three cam pins 632. The holding part 631 has the same outer diameter as that of the holding part 611. As shown in FIG. 3, the fourth lens group 84 is held on the inner surface on the front side of the holding portion 631, and the lens frame 64 is movably inserted on the rear side of the fourth lens group 84.

  The cam pin 632 is formed in the same shape as the cam pin 612, and is provided on the front side of the outer peripheral surface of the holding portion 631 as shown in FIGS. 4 and 5. Specifically, the cam pin 632 is formed so as to be positioned on the front side of the cam pin 642 of the lens frame 64 inserted into the lens frame 63. The length of the cam pin 632 is formed to be the same as the length of the cam pin 612 so that when the lens frame unit 60 is inserted into the guide tube 52, the tip protrudes from the rectilinear groove 524 in the same manner as the cam pin 612. Is set.

  As shown in FIG. 5, the holding portion 631 is formed with a notch 633 cut out along the optical axis C behind each cam pin 632. The notch 633 has a width dimension larger than the diameter dimension of the cam pin 642, and is a relief portion for the cam pin 642 to pass when the lens frame 64 moves. Further, a protrusion 636 that protrudes outward is formed on the rear side of the outer peripheral surface of the holding portion 631. Six protrusions 636 are formed at equal intervals of 60 ° in the circumferential direction around the optical axis C, and the outer dimension connecting the outer surfaces of the six protrusions 636 is the inner diameter of the small cylindrical part 522. It is set slightly smaller.

  Although not shown, three positioning pins and screw holes extending along the optical axis C are provided on the rear end surface of the lens frame 63 at equal intervals of 120 ° in the circumferential direction. The screw hole is formed as a pilot hole into which the tap screw SC is inserted, and a hole diameter slightly larger than a normal hole diameter is set so that the tightening torque of the tap screw SC becomes relatively small.

  Similarly to the lens frame 61, the lens frame 64 includes an annular holding portion 641 and three cam pins 642, and the fifth lens group 85 (see FIG. 3) is held on the inner surface of the holding portion 641. . The lens frame 64 is loosely fitted to the lens frame 63 so that the cam pin 642 protrudes from the notch 633 of the lens frame 63 and can move smoothly in the direction of the optical axis C.

  The cam pin 642 is formed in the same shape as the cam pin 612, and its length is set so that the outer diameter D2 of the lens frame 64 including the three cam pins 642 is the same as the outer diameter D1 (see FIG. 4). ing. The cam pin 642 is set so that the tip protrudes from the rectilinear groove 524 in the same manner as the cam pin 612 when the lens frame unit 60 is inserted into the guide tube 52.

  The lens frame 65 has an outer diameter that is the same as the outer diameter of the holding portion 631 and is formed in an annular shape, and a sixth lens group 86 (see FIG. 3) is held on the inner surface thereof. The lens frame 65 is arranged at the rearmost among the plurality of lens frames arranged to be movable along the optical axis C. The lens frame 65 is configured to be screwed to the rear end surface of the lens frame 63. Specifically, a hole 651 that fits the positioning pin of the lens frame 63 and a round hole 652 that corresponds to the screw hole of the lens frame 63 are formed on the outer peripheral edge of the lens frame 65. The lens frame 65 is fixed to the rear end surface of the lens frame 63 by a tap screw SC after the lens frame 64 is inserted into the lens frame 63 held by the jig.

  As described above, the lens frame unit 60 is configured such that the lens frame 63 and the lens frame 65 are fixed to each other by screws, and the lens frame 64 is movable between the lens frame 63 and the lens frame 65. It is arranged and configured as one unit that is inserted into the guide tube 52. That is, the fourth lens group 84 held by the lens frame 63 and the sixth lens group 86 held by the lens frame 65 move integrally, and the fifth lens group held by the lens frame 64. 85 can be moved between the fourth lens group 84 and the sixth lens group 86 differently from the fourth lens group 84 and the sixth lens group 86.

  As described above, the projection lens 5 emits the light beam incident from the seventh lens group 87 from the first lens group 81. The light beam emitted from the seventh lens group 87 is incident on the lens frame unit 60. The luminous flux emitted from the seventh lens group 87 is optically processed in the order of the sixth lens group 86, the fifth lens group 85, and the fourth lens group 84, and then emitted to the third lens group 83. The

FIG. 6 is a perspective view of the guide tube 52. FIG. 6 is a view of the guide tube 52 as seen from the rear side. The guide cylinder 52 will be described in detail with reference to FIGS.
The guide tube 52 is made of a synthetic resin such as PC (polycarbonate) containing glass fiber, and has the above-described large cylindrical portion 521 and small cylindrical portion 522 as shown in FIGS. The guide tube 52 is not limited to a synthetic resin and may be formed of a metal such as aluminum. Further, the guide cylinder 52 may be configured integrally by forming the large cylindrical portion 521 and the small cylindrical portion 522 as separate bodies and fixing them with screws or the like.

  The large cylindrical portion 521 has an inner diameter set to be larger than the outer diameter D1 of the lens frame 61, and is set to a size that allows the lens frames 61 and 62 and the lens frame unit 60 to be inserted. As described above, the focus screw portion 523 into which the focus screw portion 541 of the front cylinder 54 is screwed is formed on the outer peripheral surface of the large cylindrical portion 521.

  In addition, a notch 521 </ b> A for defining a rotation range of the front cylinder 54 is formed at the front end of the large cylindrical portion 521. After the front cylinder 54 is screwed into the large cylindrical portion 521, a screw is inserted into a screw hole provided on an outer peripheral surface (not shown). This screw protrudes into the notch 521A. When the front cylinder 54 rotates with respect to the guide cylinder 52, the screw comes into contact with the end surface in the circumferential direction of the notch 521A corresponding to the left and right rotation directions. Thereby, the range in which the front cylinder 54 rotates with respect to the guide cylinder 52 is defined. Further, the front cylinder 54 is structured not to be detached from the guide cylinder 52 by defining a range of rotation.

  The small cylindrical portion 522 is set so that the lens frames 61 and 62 and the lens frame unit 60 inserted from the large cylindrical portion 521 are inserted and can be smoothly moved in the direction of the optical axis C. Further, as described above, the rectilinear groove 524 is provided from the step portion formed by the large cylindrical portion 521 and the small cylindrical portion 522 toward the rear side. The rectilinear grooves 524 are engaged with the cam pins 612, 622, 632, 642, and guide the lens frames 61, 62, 63, 64, 65 along the optical axis C direction.

  Three rectilinear grooves 524 are provided at equal intervals of 120 ° in the circumferential direction around the optical axis C. The rectilinear groove 524 is formed so as to engage with the cam pins 612, 622, 632, 642 when the lens frames 61, 62 and the lens frame unit 60 are inserted from the front side of the guide tube 52. Further, the width dimension of the rectilinear groove 524 is set to be slightly larger than the outer diameter dimension of the cam pin 612.

  The rectilinear grooves 524 engage the cam pins 612, 622, 632, and 642 from both the left and right sides when the lens frames 61 and 62 and the lens frame unit 60 are inserted into the guide tube 52, respectively. The rectilinear groove 524 guides the lens frames 61, 62, 63, 64 along the optical axis C while preventing the lens frames 61, 62, 63, 64 from rotating in the left-right direction, that is, in the circumferential direction with respect to the optical axis C. It has become.

  As described above, the zoom screw portion 10 is formed on the outer peripheral surface in the vicinity of the step portion formed by the large cylindrical portion 521 and the small cylindrical portion 522 (the front edge of the small cylindrical portion 522). In the present embodiment, the zoom screw portion 10 is constituted by a single thread. Further, the zoom screw portion 10 is formed in a state of being cut by the three rectilinear grooves 524. A plurality of positioning pins 527 and screw holes 528 to which the flange 51 is attached are formed on the rear end surface of the small cylindrical portion 522.

Next, the cam cylinder 53 will be described in detail.
The cam cylinder 53 is made of a synthetic resin such as PC (polycarbonate) containing glass fiber, and the small cylindrical portion 522 of the guide cylinder 52 is inserted into the cam cylinder 53. As described above, the cam cylinder 53 is formed with a cam groove or the like that defines the movement operation of the lens frames 61, 62, 63, 64, 65 inserted into the guide cylinder 52. The cam cylinder 53 is not limited to a synthetic resin and may be formed of a metal such as aluminum.

  As shown in FIG. 4, the cam cylinder 53 has a zoom screw portion 30 formed on the inner peripheral surface of the front end portion. In the present embodiment, the zoom screw portion 30 is constituted by a single thread. The guide tube 52 is inserted into the cam tube 53 from the front side. When the guide tube 52 is inserted, the zoom screw portion 30 of the cam tube 53 is attached to the guide tube 52 by screwing with the zoom screw portion 10 of the guide tube 52. Further, the zoom screw portion 30 is formed in a state of being cut out in three guide grooves 70 described later. The cam cylinder 53 rotates in the circumferential direction around the optical axis C and is along the optical axis C when the zoom screw section 30 is screwed into the zoom screw section 10 of the guide cylinder 52. Can be moved back and forth.

  FIG. 7 is a perspective view of the cam cylinder 53. FIG. 7 is a view of the cam cylinder 53 viewed from the rear side. The configuration of the cam cylinder 53 will be described with reference to FIG.

  As shown in FIG. 7, the cam cylinder 53 has a rear protruding portion 532 that protrudes over the entire circumference on the inner peripheral surface of the rear end portion. When the small cylindrical part 522 of the guide cylinder 52 is inserted, the cam cylinder 53 is rattled with respect to the small cylindrical part 522 because the rear side protruding part 532 comes into contact with the outer surface of the small cylindrical part 522. Rotates smoothly without any problems.

  The cam cylinder 53 is formed with three bosses 533 protruding from the outer surface at equal intervals of 120 ° in the circumferential direction centered on the optical axis C on the front outer peripheral surface. The boss 533 is formed with a screw hole, and a zoom ring (not shown) is fixed to the boss 533 with a screw. As described above, the cam cylinder 53 is rotated by operating the zoom ring.

  FIG. 8 is a development view of the inner surface side of the cam cylinder 53. FIG. 8 shows one set of cam grooves among the three sets of cam grooves formed on the inner surface side of the cam cylinder 53. With reference to FIG. 8, the structure of the inner surface side of the cam cylinder 53 will be described.

  As shown in FIG. 8 (see also FIGS. 4 and 7), a guide groove 70 having a concave cross section and cam grooves 71, 72, 73, 74 formed in order from the front side are formed on the inner surface of the cam cylinder 53. Three sets are formed at equal intervals of 120 ° in the circumferential direction around the optical axis C. Further, the above-described zoom screw portion 30 is formed on the front inner surface of the cam cylinder 53.

  In FIG. 8, it is formed when a predetermined zoom adjustment is performed only with the cam groove without providing the zoom screw portion 30 with respect to the set of cam grooves 71, 72, 73, 74 (conventional case). The shapes of the cam grooves 71 ′, 72 ′, 73 ′, 74 ′ to be formed are indicated by two-dot chain lines.

  In addition, the cam cylinder 53 of the present embodiment assists the movement of the lens group by moving back and forth in the direction of the optical axis C as it rotates. Specifically, the cam cylinder 53 rotates with respect to the guide cylinder 52 when the zoom screw section 30 is screwed with the zoom screw section 10 of the guide cylinder 52, and the cam cylinder itself is in the direction of the optical axis C. Move back and forth. By this operation, the movement amount of each lens group is secured.

  The guide groove 70 is linearly formed along the optical axis C from the front end portion of the cam cylinder 53. The guide groove 70 is set so that twice the distance from the optical axis C to the bottom of the guide groove 70 is slightly larger than the outer diameter D1. The cross-sectional shape of the guide groove 70 is formed so as to follow the tip shape of the cam pins 612, 622, 632, 642. When the lens frames 61 and 62 and the lens frame unit 60 are inserted into the guide tube 52, the cam pins 612, 622, 632, and 642 that protrude from the rectilinear groove 524 are engaged with the guide groove 70.

  The cam grooves 71, 72, and 73 are each connected to the middle portion of the guide groove 70, and the cam groove 74 is connected to the terminal portion of the guide groove 70. The cam grooves 71, 72, 73, 74 are formed to be engageable with the cam pins 612, 622, 632, 642, respectively, and move the lens frames 61, 62, 63, 64, 65 along the optical axis C, respectively. Is formed. The cross-sectional shape of the cam grooves 71, 72, 73, 74 is the same as the cross-sectional shape of the guide groove 70.

  The intersections of the cam grooves 71, 72, 73, and 74 with the guide groove 70 are formed so that each lens frame is located at the most retracted position, that is, at the wide end. Further, the end portions of the cam grooves 71, 72, 73, 74 are formed so that each lens frame is located at the most extended position, that is, at the tele end. Accordingly, the cam grooves 71, 72, 73, and 74 are formed so that the second lens group 82 to the sixth lens group 86 can continuously move between each lens frame from the wide end to the tele end (zoom range). Has been. Thereby, the projection lens 5 changes the magnification of the image light.

  Specifically, the cam grooves 71, 72, 73, 74 include a spiral path as a predetermined path on the inner surface of the cam cylinder 53, including the balance with the movement of the cam cylinder 53 in the front-rear direction by the zoom screw portion 30. It is formed by a route. Further, this path is inclined forward with respect to the optical axis C, and an angle formed by the direction of the path (cam groove) (tangential direction of the cam groove) and a direction perpendicular to the optical axis C (Hereinafter referred to as a standing angle) is set in correspondence with a predetermined relative position of each lens frame.

  When the cam cylinder 53 rotates rightward about the optical axis C, the cam cylinder 53 moves rearward, and the cam grooves 71, 72, 73, and 74 move the lens frames to the wide end side. Is set to Further, when the cam cylinder 53 rotates leftward about the optical axis C, the cam cylinder 53 moves forward and each lens frame moves to the tele end side. It should be noted that the rotation angle range of the cam cylinder 53 of this embodiment is approximately 60 °, and is set so that each lens frame can move in the zoom range.

  Further, the cam grooves 71, 72, 73, 74, the zoom screw portion 30 of the cam cylinder 53, and the zoom screw portion 10 of the guide cylinder 52 have optical characteristics such as predetermined zooming and aberration compensation of the image light. The standing angle is set to be small within a range that does not impair the operability of rotating the cam cylinder 53 while ensuring. As shown in FIGS. 3 and 8, the length L in the optical axis C direction of the cam barrel 53 is set to be short. Note that the projection lens 5 of the present embodiment is set so that the magnification of the image light can be changed by about 1.6 times.

  Each lens frame is moved along the optical axis C as each cam pin is guided to the intersection of the straight advance groove 524 and each cam groove by the rotation of the cam cylinder 53. Specifically, the lens frame 61 moves with the cam pins 612 guided by the cam grooves 71, and the lens frame 62 moves with the cam pins 622 guided by the cam grooves 72. The lens frames 63 and 65 move with the cam pin 632 guided by the cam groove 73, and the lens frame 64 moves with the cam pin 642 guided by the cam groove 74. In addition, the lens frames 63 and 65 are guided by a cam pin 632 provided in front of the cam pin 642, but the inclination with respect to the optical axis C is suppressed by the protrusion 636 described above, and smooth movement is possible.

  As described above, the second lens group 82 to the sixth lens group 86 respectively held by the lens frames 61 to 65 move along the optical axis C as the cam cylinder 53 rotates with respect to the guide cylinder 52. To do. Then, the projection lens 5 projects the image light by changing the magnification according to the position of the moved lens group.

Here, the difference between the conventional cam grooves 71 ′, 72 ′, 73 ′, 74 ′ and the cam grooves 71, 72, 73, 74 of the present embodiment will be described.
As shown in FIG. 8, when comparing the cam groove 74 ′ and the cam groove 74, the standing angle A <b> 1 at the point A of the cam groove 74 is the standing angle at the point B of the conventional cam groove 74 ′ corresponding to the point A. It is smaller than B1. Therefore, when the cam pin 642 moves following the cam groove 74, the torque at the point A can be reduced as compared with the conventional case. The cam grooves 71, 72, 73, 74 can be set with a smaller standing angle than the conventional cam grooves 71 ′, 72 ′, 73 ′, 74 ′. The torque when rotating with respect to the cylinder 52 can be reduced as compared with the conventional case.

  Further, since the standing angle can be reduced as compared with the conventional case, the gap between the cam grooves 71, 72, 73, 74 in the optical axis C direction and the corresponding cam pins 612, 622, 632, 642 is conventionally increased. The lens frame 61, 62, 63, 64 (second lens group 82 to fifth lens group 85) can be prevented from being tilted with respect to the optical axis C.

According to the first embodiment described above, the following effects can be obtained.
According to the projection lens 5 of the present embodiment, a screw portion is formed as the engaging portion, and as the screw portion, the zoom screw portion 10 is provided on the outer peripheral surface of the guide tube 52 and the zoom screw is provided on the inner peripheral surface of the cam tube 53. The zoom screw portions 10 and 30 are engaged with each other. In addition, the zoom screw portions 10 and 30 cause the cam cylinder 53 to move in the front-rear direction along the optical axis C by rotating in the circumferential direction with respect to the guide cylinder 52. With this configuration, the movement of the internal lens group can be assisted to suppress the standing angle of the cam grooves 71, 72, 73, 74 formed in the cam cylinder 53, and each along the optical axis C can be suppressed. The amount of movement of the lens group can be ensured. Therefore, by providing the threaded portion (zoom threaded portion 10, 30) as the engaging portion, it is possible to suppress an increase in the standing angle even when the magnification of the projection lens 5 is increased, so that the desired magnification is obtained. Zoom adjustment is possible.

  According to the projection lens 5 of the present embodiment, the outer peripheral surface of the guide tube 52 and the inner peripheral surface of the cam tube 53 have screw portions (zoom screw portions 10 and 30) as engaging portions. Is engaged. Since the engaging portion is configured by a screw portion, a configuration for moving the cam cylinder 53 along the optical axis C can be easily realized.

  According to the projection lens 5 of the present embodiment, it is possible to suppress an increase in the standing angle of the cam grooves 71, 72, 73, 74 of the cam cylinder 53, so that the cam cylinder 53 is rotated in the circumferential direction of the guide cylinder 52. Therefore, the cam cylinder 53 rotates smoothly with respect to the guide cylinder 52. Therefore, the operational feeling of the zoom ring (zoom adjustment lever) installed in the cam cylinder 53 can be improved.

  According to the projection lens 5 of the present embodiment, the rising angle of the cam grooves 71, 72, 73, 74 of the cam cylinder 53 can be suppressed, so that the cam grooves 71, 72, 73, 74 in the optical axis C direction. And the corresponding cam pins 612, 622, 632, 642 can be suppressed. Thereby, since it can suppress that the lens frames 61, 62, 63, and 64 (the 2nd lens group 82-the 5th lens group 85) incline with respect to the optical axis C, the optical performance of the projection lens 5 can be taken out. .

According to the projector 1 of the present embodiment, by providing the projection lens 5 that can suppress an increase in the standing angle even when the magnification of the projection lens 5 is increased, it is desired even when the projection lens 5 with a high magnification is used. It is possible to realize the projector 1 that can smoothly adjust the cam cylinder 53 so as to achieve zooming and can improve the quality of image light to be projected.
(Second Embodiment)

  FIG. 9 is a schematic cross-sectional view of the projection lens according to the second embodiment. The configuration and operation of the projection lens 5A will be described with reference to FIG.

  The projection lens 5A of the present embodiment is different in the configuration of the engaging portion from the projection lens 5 of the first embodiment. In the first embodiment, a screw portion is provided as the engaging portion. Further, as the threaded portion, the guide tube 52 has the zoom threaded portion 10, and the cam tube 53 has the zoom threaded portion 30. The present embodiment is different in that the guide tube 52A has the cam groove 11 and the cam tube 53A has the cam pin 31 as the engaging portion. The other components are configured in the same manner as in the first embodiment. Therefore, the same code | symbol is attached | subjected to the same structure part.

  As shown in FIG. 9, the cam pin 31 included in the cam cylinder 53 </ b> A is formed so as to protrude inward from the inner peripheral surface on the front side of the cam cylinder 53 </ b> A in the direction intersecting the optical axis C, and centered on the optical axis C. Three are provided at equal intervals of 120 ° in the circumferential direction. The cam pin 31 is formed in a tapered columnar shape whose tip is narrowed. The three cam pins 31 are set to the same length.

  The cam groove 11 is a component for engaging with the cam pin 31 described above and defining the movement operation of the cam pin 31. The cam groove 11 is formed in a concave shape in a predetermined path on the outer peripheral surface on the front side of the small cylindrical portion 522 of the guide cylinder 52A. Three sets of cam grooves 11 are formed at equal intervals of 120 ° in the circumferential direction around the optical axis C, corresponding to the three cam pins 31 respectively. The cam groove 11 is formed to assist the movement of each lens group in accordance with the movement operation of the second lens group 82 to the sixth lens group 86 defined by the cam grooves 71, 72, 73, 74. ing.

  When the cam cylinder 53A is rotated, each of the lens frames 61, 62, 63, 64, and 65 has the cam pins 612, 622, 632, and 642 rotated by the cam cylinder 53A so that the rectilinear groove 524 and the cam grooves 71, 72, and 73 are rotated. , 74, and moves in the direction of the optical axis C. In conjunction with this operation, the cam pin 31 of the cam cylinder 53A engages and rotates with the cam groove 11 of the guide cylinder 52A, and the cam cylinder 53A moves in the direction of the optical axis C, whereby each lens frame 61, 62, The movement of 63, 64, 65 is assisted. This operation enables zoom adjustment of image light.

According to 2nd Embodiment mentioned above, the following effects are acquired similarly to 1st Embodiment.
According to the projection lens 5A of the present embodiment, the engaging groove has the cam groove 11 on the outer peripheral surface of the guide tube 52A and the cam pin 31 on the inner peripheral surface of the cam tube 53A. And engage. The cam groove 53 and the cam pin 31 cause the cam cylinder 53A to move in the front-rear direction along the optical axis C by rotating in the circumferential direction with respect to the guide cylinder 52A. With this configuration, the movement of the internal lens group can be assisted to suppress the standing angle of the cam grooves 71, 72, 73, 74 formed in the cam cylinder 53A. The amount of movement of the lens group can be ensured. Therefore, by providing the cam groove 11 and the cam pin 31 as the engaging portion, even when the magnification of the projection lens 5A is increased, the rising angle can be suppressed, and zoom adjustment can be performed so as to obtain a desired magnification. .

According to the projection lens 5A of the present embodiment, the engaging portion is constituted by the cam groove 11 provided on the outer peripheral surface of the guide cylinder 52A and the cam pin 31 provided on the inner peripheral surface of the cam cylinder 53A, whereby the cam cylinder. A configuration for moving 53A along the optical axis C is easily realized.
Since effects other than those described above are the same as those in the first embodiment, description thereof is omitted.

  Note that the present invention is not limited to the first and second embodiments described above, and various modifications and improvements can be made without departing from the scope of the invention. A modification will be described below.

  In the projection lens 5 of the first embodiment, the zoom screw portion 30 formed on the cam barrel 53 is formed on the inner peripheral surface of the front end portion of the cam barrel 53. However, the present invention is not limited to this, and the zoom screw portion may be formed on the inner peripheral surface of the rear end portion of the cam cylinder 53. In this case, the zoom screw portion formed on the guide tube 52 that engages with the zoom screw portion formed on the cam tube 53 may be appropriately changed. The same applies to the cam groove 11 and the cam pin 31 in the second embodiment.

  In the projection lens 5 of the first embodiment, the zoom screw portion 30 formed on the cam cylinder 53 is cut by a guide groove 70 formed on the inner peripheral surface of the cam cylinder 53. However, the present invention is not limited to this, and a configuration in which the inner diameter shape of the cam cylinder is changed and the guide groove 70 is not cut may be employed.

  In the projection lens 5 of the first embodiment, the zoom screw portion 30 formed on the cam cylinder 53 is formed by a single screw, but may be formed by two or more helicoid screws. The thread groove shape can be changed as appropriate. In addition, when the screw part as the engaging part is composed of a helicoid screw, when performing zoom adjustment to achieve a desired zoom, the moving distance of the cam cylinder in the optical axis direction is smaller than that of the single thread screw. Can be shortened. Therefore, the length in the optical axis direction can be suppressed even with a high magnification projection lens, and the projection lens can be miniaturized.

  In the projection lens 5A of the second embodiment, the engaging portion has the cam groove 11 on the outer peripheral surface of the guide cylinder 52A and the cam pin 31 on the inner peripheral surface of the cam cylinder 53A. However, the present invention is not limited to this, and a configuration may be adopted in which a cam pin is provided on the outer peripheral surface of the guide cylinder 52A and a cam groove is provided on the inner peripheral surface of the cam cylinder 53A.

  The projection lens 5 of the first embodiment is configured to have seven lens groups, that is, the first lens group 81 to the seventh lens group 87. However, the projection lens 5 may be configured of other number of lens groups. Good. The same applies to the projection lens 5A of the second embodiment.

  The projection lens 5 according to the first embodiment is configured such that the cam cylinder 53 and the front cylinder 54 are manually rotated. However, the cam cylinder 53 and the front cylinder 54 are rotated electrically by using a motor or the like. You may comprise. The same applies to the projection lens 5A of the second embodiment.

  The cam grooves 71, 72, 73, 74 of the first embodiment are such that each lens frame moves to the wide end side when the cam cylinder 53 rotates to the right, and each lens frame moves to the tele end when the cam barrel 53 rotates to the left. However, it may be formed so as to move toward the tele end when rotated in the right direction and to move toward the wide end when rotated in the left direction. The same applies to the projection lens 5A of the second embodiment.

  The projection lens 5 of the first embodiment is configured such that focus adjustment is possible, that is, the focal length can be changed, but it may be configured as a single focal lens having a fixed focal length. The projection lens 5 of the first embodiment is configured such that the rotating cam cylinder 53 is exposed to the outside, but a fixing member is provided as a member exposed to the outside, and the fixing member is provided inside the fixing member. The cam cylinder 53 may be disposed, and each lens group may be moved by rotating the cam cylinder 53 with respect to the fixing member. The same applies to the projection lens 5A of the second embodiment.

  In the projectors 1 of the first and second embodiments, the electro-optical device 25 employs a so-called three-plate method using three light modulation devices corresponding to R light, G light, and B light. However, the present invention is not limited to this, and a single plate type light modulation device may be adopted. Further, a light modulation device for improving the contrast may be additionally employed.

  In the projectors 1 of the first and second embodiments, the electro-optical device 25 employs a transmissive light modulation device (transmissive liquid crystal panel 253). However, the present invention is not limited to this, and a reflective light modulation device may be employed.

  In the projector 1 of the first and second embodiments, the electro-optical device 25 employs a liquid crystal panel 253 as a light modulation device. However, the present invention is not limited to this, and it is generally sufficient that it modulates an incident light beam based on an image signal. For example, another type of light modulation device such as a micromirror light modulation device can be employed. For example, a DMD (Digital Micromirror Device) can be adopted as the micromirror type light modulation device.

  In the projectors 1 of the first and second embodiments, the optical unit 2 is an illuminating optical device 22 that equalizes the illuminance of the light beam emitted from the light source device 21, from the first lens array 221 and the second lens array 222. The lens integrator optical system is adopted. However, the present invention is not limited to this, and a rod integrator optical system including a light guide rod can also be employed.

  In the optical unit 2 of the projector 1 of the first and second embodiments, the light source 211 of the light source device 21 employs a discharge lamp such as an ultra-high pressure mercury lamp, but a laser diode, LED (Light Emitting Diode). Various solid light emitting elements such as organic EL (Electro Luminescence) elements and silicon light emitting elements may be employed.

  DESCRIPTION OF SYMBOLS 1 ... Projector, 5 and 5A ... Projection lens, 10 and 30 ... Screw part for zoom, 11 ... Cam groove, 31 ... Cam pin, 52, 52A ... Guide cylinder, 53, 53A ... Cam cylinder, 61-65 ... Lens frame, 70: guide groove, 71, 72, 73, 74 ... cam groove, 81 ... first lens group, 82 ... second lens group, 83 ... third lens group, 84 ... fourth lens group, 85 ... fifth lens group 86 ... Sixth lens group, 87 ... Seventh lens group, 211 ... Light source, 253 ... Liquid crystal panel, 524 ... Straight groove, 612, 622, 632, 642 ... Cam pin.

Claims (5)

A projection lens,
A plurality of lenses fixed to a lens frame having cam pins on the outer periphery;
A guide cylinder formed along the optical axis of the projection lens and penetrating therethrough, engaging the cam pin in the rectilinear groove, and sequentially arranging and guiding the plurality of lenses;
The inner peripheral surface has a plurality of cam grooves that are formed in a predetermined path corresponding to the plurality of lenses and engages the cam pin, and the guide tube is inserted, and the guide tube is inserted in a circumferential direction. A cam cylinder that moves the plurality of lenses along the optical axis by rotation to
The outer peripheral surface of the guide tube and the inner peripheral surface of the cam tube have engaging portions that engage with each other, and the cam tube moves along the optical axis by the rotation. Projection lens. The projection lens according to claim 1,
The projection lens according to claim 1, wherein the engaging portion includes a screw portion. The projection lens according to claim 2,
The projection lens, wherein the screw portion is formed of a helicoid screw. The projection lens according to claim 1,
The projection lens is characterized in that the engaging portion has a cam pin in one of the guide tube and the cam tube, and has a cam groove engaged with the cam pin in the other. A light source;
A light modulation device that modulates a light beam emitted from the light source based on image information to form image light;
The projection lens according to any one of claims 1 to 4, which projects the image light;
A projector comprising:

Images