Projection lens and projection device

A projection lens has a first rotary tube, a first fixed tube at which the first rotary tube is rotatably mounted, a first protrusion portion that is provided at the first rotary tube and that protrudes from the first rotary tube, and a first abutment surface that is provided at the first fixed tube and that abuts upon the first protrusion portion. The projection lens includes a first engaging portion at which the first protrusion portion and the first abutment surface include first engaging portions that face each other in a direction of a first incidence-side optical axis and a first pressing portion that presses the first protrusion portion against the first abutment surface.

BACKGROUND OF THE INVENTION

Technical Field

The technology of the present disclosure relates to a projection lens and a projection device.

Related Art

Projectors, which are projection devices that project an image onto a screen, are widely used. Projectors include, for example, an image formation panel, such as a liquid crystal display element (LCD: liquid crystal display) or a DMD (digital micromirror device: registered trademark), and a projection lens that projects onto a screen an image that is formed at the image formation panel.

Among such projectors, a projector including a projection lens that can change a projection direction of an image is being developed (refer to WO2018/055964A). In the projector that is described in WO2018/055964A, the image formation panel is accommodated in a main body portion, and the projection lens is mounted on an outer peripheral surface of the main body portion.

In the projector that is described in WO2018/055964A, a light beam that represents an image formed at the image formation panel is incident upon the projection lens from the main body portion. The projection lens includes a bending optical system having three optical axes that are a first optical axis, a second optical axis, and a third optical axis in this order from an incidence side. The first optical axis is an optical axis that corresponds to a light beam that is incident from the main body portion, and the second optical axis is bent by 90° with respect to the first optical axis. The third optical axis is bent by 90° with respect to the second optical axis, and is an exit optical axis along which a light beam exits toward a screen.

The projection lens has an incidence-side end portion, an intermediate portion, and an exit-side end portion. The incidence-side end portion corresponds to the first optical axis. The intermediate portion corresponds to the second optical axis. The exit-side end portion corresponds to the third optical axis. The incidence-side end portion is nonrotatably mounted with respect to the main body portion, and the intermediate portion rotates around the first optical axis with respect to the incidence-side end portion. The exit-side end portion is connected to the intermediate portion, and, when the intermediate portion rotates, the exit-side end portion also rotates around the first optical axis. The exit-side end portion rotates around the second optical axis with respect to the intermediate portion. In this way, due to the exit-side end portion rotating around the first optical axis and the second optical axis, the projection direction is changed.

In such a projection lens, for example, in order to rotate the exit-side end portion with respect to the intermediate portion, a lens barrel that accommodates the bending optical system has a rotary tube that rotates around an optical axis that extends through the intermediate portion and a fixed tube on which the rotary tube is rotatably mounted. When such a rotary tube and a fixed tube are used, optical-axis shifts caused by the rotation of the rotary tube may occur.

SUMMARY

An object of the technology of the present disclosure is to provide a projection lens and a projection device, in which, in the projection lens that includes a bending optical system having at least two optical axes that are bent and a rotary tube rotating around an optical axis, it is possible to suppress optical-axis shifts caused by the rotation of the rotary tube.

A projection lens of the present disclosure is a projection lens that is to be mounted on a housing of a projection device having an electro-optical element, and that includes a bending optical system, an exit-side lens barrel portion, a first incidence-side lens barrel portion, a first protrusion portion, a first abutment surface, and a first pressing portion. The bending optical system includes at least two optical axes, the two optical axes being an exit-side optical axis along which light incident from the housing exits and a first incidence-side optical axis that is disposed on an incidence side with respect to the exit-side optical axis and that is bent with respect to the exit-side optical axis. The exit-side lens barrel portion accommodates an exit-side optical system having the exit-side optical axis and rotates around the first incidence-side optical axis. The first incidence-side lens barrel portion is disposed on an incidence side with respect to the exit-side lens barrel portion and has the first incidence-side optical axis extending therethrough, the first incidence-side lens barrel portion having a first rotary tube and a first fixed tube, the first rotary tube rotating around the first incidence-side optical axis as a result of rotating the exit-side lens barrel portion, the first rotary tube being rotatably mounted at the first fixed tube. The first protrusion portion is provided at one of the first rotary tube and the first fixed tube and protrudes from the one of the first rotary tube and the first fixed tube. The first abutment surface is provided at the other of the first rotary tube and the first fixed tube and faces and abuts upon the first protrusion portion. The first pressing portion presses the first protrusion portion against the first abutment surface by pressing at least one of the first rotary tube or the first fixed tube in a direction of the first incidence-side optical axis.

It is desirable that the one of the first rotary tube and the first fixed tube be an outer tube, and the other of the first rotary tube and the first fixed tube be an inner tube that is inserted in an inner portion of the outer tube, the first protrusion portion be provided at an outer peripheral surface of the inner tube and protrude toward an inner peripheral surface of the outer tube, an accommodation groove that is capable of accommodating at least a part of the first protrusion portion be formed in the inner peripheral surface of the outer tube in a peripheral direction of the first incidence-side optical axis, and the first abutment surface be formed at one surface of an inner portion of the accommodation groove.

It is desirable that the first pressing portion be provided at the one of the first rotary tube and the first fixed tube; that the projection lens include a first press surface and at least one first fitting hole, the first press surface being provided at the other of the first rotary tube and the first fixed tube, being disposed so as to face the first pressing portion in the direction of the first incidence-side optical axis, and being pressed by the first pressing portion, and the at least one first fitting hole being provided in the first press surface and being fitted to the first pressing portion; and that when the exit-side lens barrel portion rotates around the first incidence-side optical axis, a state of the first pressing portion is switched between a fitting state in which the first pressing portion is fitted to the first fitting hole and a move-out state in which the first pressing portion moves out of the first fitting hole.

It is desirable that when the direction of the first incidence-side optical axis is a horizontal direction that is orthogonal to a gravitation direction, and when a rotation force that rotates the exit-side lens barrel portion around the first incidence-side optical axis by an action of gravitation is T1 and a rotation restriction force that restricts rotation of the exit-side lens barrel portion around the first incidence-side optical axis and that is generated based on a pressing force of the first pressing portion is F1, Formula (1) below be satisfied:
F1>T1  Formula (1).

It is desirable that the bending optical system include a second incidence-side optical axis that is disposed on an incidence side with respect to the first incidence-side optical axis and that is bent with respect to the first incidence-side optical axis, and that the projection lens further include a second incidence-side lens barrel portion, a second protrusion portion, a second abutment surface, and a second pressing portion. The second incidence-side lens barrel portion is disposed on an incidence side with respect to the first incidence-side lens barrel portion and has the second incidence-side optical axis extending therethrough, the second incidence-side lens barrel portion having a second rotary tube that rotates around the second incidence-side optical axis as a result of rotating the first incidence-side lens barrel portion and a second fixed tube at which the second rotary tube is rotatably mounted. The second protrusion portion is provided at one of the second rotary tube and the second fixed tube and protrudes from the one of the second rotary tube and the second fixed tube. The second abutment surface is provided at the other of the second rotary tube and the second fixed tube and faces and abuts upon the second protrusion portion. The second pressing portion presses the second protrusion portion against the second abutment surface by pressing at least one of the second rotary tube or the second fixed tube in a direction of the second incidence-side optical axis.

It is desirable that when the direction of the second incidence-side optical axis is a horizontal direction that is orthogonal to a gravitation direction, and when a rotation force that rotates the exit-side lens barrel portion and the first incidence-side lens barrel portion around the second incidence-side optical axis by an action of gravitation is T2 and a rotation restriction force that restricts rotation of the exit-side lens barrel portion and the first incidence-side lens barrel portion around the second incidence-side optical axis and that is generated based on a pressing force of the second pressing portion is F2, Formula (2) below be satisfied:
F2>T2  Formula (2).

It is desirable that the rotation restriction force F1 and the rotation restriction force F2 further satisfy Formula (3) below:
F1<F2  Formula (3).

It is desirable that the first protrusion portion be a ball bearing.

It is desirable that at least four of the first fitting holes be provided, and the four first fitting holes be disposed at an interval of 90° around the first incidence-side optical axis.

It is desirable that a plurality of the first pressing portions be provided.

It is desirable that at least three of the first pressing portions be provided.

It is desirable that the plurality of the first pressing portions include two or more types of the first pressing portions whose pressing forces differ from each other.

It is desirable that the projection lens include a first connection frame that connects the exit-side lens barrel portion and the first incidence-side lens barrel portion to each other.

It is desirable that the first pressing portions be mounted at an outer peripheral surface of the first connection frame.

It is desirable that the first pressing portion be a ball plunger.

A different projection lens of the present disclosure is a projection lens that is to be mounted on a housing of a projection device having an electro-optical element, and that includes a bending optical system, an exit-side lens barrel portion, a first incidence-side lens barrel portion, a first pressing portion, a first press surface, and at least one first fitting hole. The bending optical system includes at least two optical axes, the two optical axes being an exit-side optical axis along which light incident from the housing exits and a first incidence-side optical axis that is disposed on an incidence side with respect to the exit-side optical axis and that is bent with respect to the exit-side optical axis. The exit-side lens barrel portion accommodates an exit-side optical system having the exit-side optical axis and rotates around the first incidence-side optical axis. The first incidence-side lens barrel portion is disposed on an incidence side with respect to the exit-side lens barrel portion and has the first incidence-side optical axis extending therethrough, the first incidence-side lens barrel portion having a first rotary tube and a first fixed tube, the first rotary tube rotating around the first incidence-side optical axis as a result of rotating the exit-side lens barrel portion, the first rotary tube being rotatably mounted at the first fixed tube. The first pressing portion is provided at one of the first rotary tube and the first fixed tube and presses the other of the first rotary tube and the first fixed tube. The first press surface is provided at the other of the first rotary tube and the first fixed tube and is pressed by the first pressing portion. The at least one first fitting hole is provided in the first press surface and is fitted to the first pressing portion. In the projection lens, when the exit-side lens barrel portion rotates around the first incidence-side optical axis, a state of the first pressing portion is switched between a fitting state in which the first pressing portion is fitted to the first fitting hole and a move-out state in which the first pressing portion moves out of the first fitting hole.

The different projection lens includes a plurality of the first pressing portions, in which the number of the first fitting holes is at least one or more, and in which the number of the first fitting holes is less than the number of the first pressing portions.

A projection device of the present disclosure includes any one of the projection lenses above.

According to the present disclosure, in the projection lens that includes a bending optical system having at least two optical axes that are bent and a rotary tube rotating around an optical axis, it is possible to suppress optical-axis shifts caused by the rotation of the rotary tube.

DETAILED DESCRIPTION

An example of an embodiment of the technology of the present disclosure is described below with reference to the drawings.

Note that terms, such as “first”, “second”, and “third”, used in the present specification are added to avoid confusion between structural elements, and do not limit the number of structural elements that exist in a projector or a lens.

As illustrated inFIG.1, a projector10of the present embodiment corresponds to a projection device, and includes a projection lens11and a main body portion12. One end portion of the projection lens11is mounted on the main body portion12.FIG.1illustrates the projection lens11in an accommodated state when the projector10is not used.

The main body portion12includes a base portion12A, a protrusion portion12B, and an accommodation portion12C. The base portion12A accommodates main components, such as an image formation unit26(refer toFIG.4) and a control board (not illustrated).

The base portion12A corresponds to a central portion. In plan view ofFIG.1, the base portion12A has a substantially rectangular shape that is long sideways. The protrusion portion12B protrudes from one side of the base portion12A. The protrusion portion12B has a substantially rectangular shape, and the width of the protrusion portion12B is about half of the length of the one side of the base portion12A. Therefore, the main body portion12has a substantially L shape in plan view as a whole in which the base portion12A and the protrusion portion12B are combined.

The accommodation portion12C accommodates the projection lens11. InFIG.1, the accommodation portion12C is a space that is provided on the left side of the protrusion portion12B, and has a substantially rectangular shape in plan view similarly to the protrusion portion12B. That is, inFIG.1, it is assumed that, of an outer peripheral surface of the main body portion12, an upper-side side surface12D and a left-side side surface12E are extended in a direction in which the side surface12D and the side surface12E intersect each other. A space that is defined by the extended side surfaces12D and12E as outer edges is the accommodation portion12C. Therefore, although the main body portion12has a substantially L shape in terms of a single body, when the main body portion12is seen as a whole in which the accommodation portion12C is included, the main body portion12has a substantially rectangular shape in plan view. Since the accommodation portion12C can also be seen as a portion that is recessed toward a side of the base portion12A with respect to the height of the protrusion portion12B when the projector10is vertically placed, the accommodation portion12C corresponds to a recessed portion.

When the projector10is not used, the projection lens11is accommodated in the accommodation portion12C with the projection lens11being deformed so as not to protrude from the rectangular accommodation portion. Therefore, as illustrated inFIG.1, in the accommodated state, the projector10has a substantially rectangular parallelepiped shape with reduced irregularity in the outer peripheral surface as a whole in which the L-shaped main body portion12and the projection lens11are combined. Consequently, in the accommodated state, the projector10is easily carried and accommodated.

A light beam that represents an image formed by the image formation unit26is incident upon the projection lens11from the main body portion12. The projection lens11forms an image by enlarging image light based on the incident light beam by an optical system. Therefore, the projection lens11projects onto a screen36(refer toFIG.4) an enlarged image of the image formed by the image formation unit26.

The projection lens11has, for example, a bending optical system (refer toFIGS.2and3) that bends an optical axis twice, and, in the accommodated state illustrated inFIG.1, the projection lens11has a substantially U shape with a convex shape on an upper side as a whole. The projection lens11includes an incidence-side end portion14A, an intermediate portion14B, and an exit-side end portion14C. The incidence-side end portion14A is connected to one end of both ends of the intermediate portion14B, and the exit-side end portion14C is connected to the other end of both the ends of the intermediate portion14B. Light from the main body portion12is incident upon the incidence-side end portion14A. An exit lens16is provided at the exit-side end portion14C. The light incident upon the incidence-side end portion14A from the main body portion12is guided to the exit-side end portion14C via the intermediate portion14B. The exit-side end portion14C allows the light that has been guided from the main body portion12via the incidence-side end portion14A and the intermediate portion14B to exit from the exit lens16toward the screen36.

The incidence-side end portion14A is mounted on the main body portion12. A position where the incidence-side end portion14A is mounted is, in a left-right direction inFIG.1, adjacent to the protrusion portion12B and near the center of the base portion12A. In the accommodated state of the projection lens11, the intermediate portion14B extends toward a side of an end portion opposite to the protrusion portion12B, that is, toward the left inFIG.1from a position near the center of the base portion12A. A corner portion14D of the exit-side end portion14C and a corner portion12F of the protrusion portion12B are disposed at positions that are substantially symmetrical in the left-right direction inFIG.1.

The outer shape of the exit-side end portion14C is formed so as to be substantially the same as the outer shape of the protrusion portion12B, and the outer shape of the projection lens11and the outer shape of the main body portion12are made common. Therefore, in the accommodated state, the outer shape of the projection lens11is designed as if the outer shape of the projection lens11constitutes a part of the outer shape of the main body portion12.

As illustrated inFIGS.2and3, the projection lens11includes the bending optical system. The bending optical system has a first optical axis A1, a second optical axis A2, and a third optical axis A3. The second optical axis A2is an optical axis that is bent by 90° with respect to the first optical axis A1. The third optical axis A3is an optical axis that is bent by 90° with respect to the second optical axis A2.

The incidence-side end portion14A is nonrotatably mounted with respect to the main body portion12. The intermediate portion14B is rotatable around the first optical axis A1with respect to the incidence-side end portion14A. Since the exit-side end portion14C is connected to the intermediate portion14B, when the intermediate portion14B rotates with respect to the incidence-side end portion14A, the exit-side end portion14C also rotates around the first optical axis A1. A rotatable range around the first optical axis A1is less than 360°, and, in the present example, is 180°. The rotatable range around the first optical axis A1is limited to less than 360° for preventing interference between the protrusion portion12B and the projection lens11in a state in which the protrusion portion12B is adjacent to the incidence-side end portion14A.

The exit-side end portion14C is rotatable around the second optical axis A2with respect to the intermediate portion14B. Unlike the intermediate portion14B, the rotation of the exit-side end portion14C around the second optical axis A2is not limited. For example, the exit-side end portion14C can also be rotated by 360° or greater.

In summary, the exit-side end portion14C is rotatable around two rotational axes that are the first optical axis A1and the second optical axis A2. Therefore, a user can change a projection direction of the projection lens11without moving the main body portion12.

FIG.2illustrates the projector10in a horizontally placed state with respect to an installation surface18, andFIG.3illustrates the projector10in a vertically placed state with respect to the installation surface18. In this way, the projector10can be used in a horizontally placed orientation and in a vertically placed orientation.

As illustrated inFIG.3, an operation panel22is provided at the side surface12D of the protrusion portion12B. The operation panel22has a plurality of operation switches. The operation switches are, for example, a power switch and adjustment switches. The adjustment switches are switches for performing various types of adjustments. Examples of adjustment switches include switches for adjusting image quality of an image that has been projected onto the screen36and performing trapezoidal correction.

A first unlocking switch24A and a second unlocking switch24B are provided at one surface of the intermediate portion14B. A first rotation locking mechanism and a second rotation locking mechanism are provided at the projection lens11. The first rotation locking mechanism locks the rotation of the intermediate portion14B around the first optical axis A1with respect to the incidence-side end portion14A. The second rotation locking mechanism locks the rotation of the exit-side end portion14C around the second optical axis A2with respect to the intermediate portion14B. The first unlocking switch24A is an operation switch for inputting to the first rotation locking mechanism an instruction to unlock the rotation of the intermediate portion14B. The second unlocking switch24B is an operation switch for inputting to the second rotation locking mechanism an instruction to unlock the rotation of the exit-side end portion14C.

As illustrated inFIG.4, the image formation unit26is provided in the main body portion12. The image formation unit26forms an image to be projected. The image formation unit26includes, for example, an image formation panel32, a light source34, and a light guide member (not illustrated). The image formation panel32is an example of an electro-optical element.

The light source34emits light to the image formation panel32. The light guide member guides the light from the light source34to the image formation panel32. The image formation unit26is, for example, a reflective-type image formation unit that uses a DMD as the image formation panel32. As is well known, the DMD has a plurality of micromirrors that are capable of changing a reflection direction of the light that is emitted from the light source34, and is an image display element in which each micromirror is disposed two-dimensionally in a pixel unit. The DMD, by switching an on/off state of reflected light of the light from the light source34as a result of changing the orientation of each micromirror in accordance with an image, performs light modulation in accordance with the image.

An example of the light source34is a white light source. The white light source emits white light. The white light source is, for example, a light source that is realized by combining a laser light source and a fluorescent body. The laser light source emits blue light, as excitation light, with respect to the fluorescent body. The fluorescent body emits yellow light by being excited by the blue light emitted from the laser light source. The white light source emits the white light by combining the blue light that is emitted from the laser light source and the yellow light that is emitted from the fluorescent body. A rotary color filter that selectively converts by time division the white light that is emitted by the light source34into each colored light ray, that is, a blue light B (Blue) ray, a green light G (Green) ray, and a red light R (Red) ray is further provided at the image formation unit26. Each of the colored light B, G, and R rays selectively illuminates the image formation panel32to obtain image light rays carrying pieces of image information about the respective colors of B, G, and R. The image light rays of the respective colors obtained in this way are selectively incident upon the projection lens11and thus are projected toward the screen36. The image light rays of the respective colors are combined on the screen36and a full-color image P is displayed on the screen36.

As illustrated inFIGS.5and6, the projection lens11includes a lens barrel40. The lens barrel40accommodates the bending optical system. The lens barrel40includes a first lens barrel portion41, a second lens barrel portion42, and a third lens barrel portion43. The first lens barrel portion41, the second lens barrel portion42, and the third lens barrel portion43each accommodate a lens. The lens that is accommodated in the first lens barrel portion41is disposed on the first optical axis A1. The lens that is accommodated in the second lens barrel portion42is disposed on the second optical axis A2. The lens that is accommodated in the third lens barrel portion43is disposed on the third optical axis A3. A center axis of the first lens barrel portion41substantially coincides with the first optical axis A1. A center axis of the second lens barrel portion42substantially coincides with the second optical axis A2. A center axis of the third lens barrel portion43substantially coincides with the third optical axis A3.FIGS.5and6illustrate the lens barrel40in the states illustrated inFIGS.2and4. Note that, in the present embodiment, in order to simplify the description, each lens is described as if each lens is one lens with a detailed structure of each lens being omitted. However, each lens may be a plurality of lenses.

The first lens barrel portion41is a lens barrel portion that is positioned on a most incidence side, the third lens barrel portion43is a lens barrel portion that is positioned on a most exit-side, and the second lens barrel portion42is a lens barrel portion that is positioned between the first lens barrel portion41and the third lens barrel portion43.

Further, the lens barrel40includes a first mirror holding portion44and a second mirror holding portion46. The first mirror holding portion44holds a first mirror48, and the second mirror holding portion46holds a second mirror49. The first mirror48and the second mirror49are each one optical element that constitutes the bending optical system, and are each a reflective portion that bends an optical axis. The first mirror48forms the second optical axis A2by bending the first optical axis A1. The second mirror49forms the third optical axis A3by bending the second optical axis A2. The first mirror holding portion44is disposed between the first lens barrel portion41and the second lens barrel portion42. The second mirror holding portion46is disposed between the second lens barrel portion42and the third lens barrel portion43.

An end portion of an inner tube42B of the second lens barrel portion42and a lens L22that is held by the end portion are disposed in an inner portion of the second mirror holding portion46. Therefore, the distance between the lens L22and the second mirror49is reduced, and, even if the second mirror49is reduced in size, the second mirror49is capable of reflecting light from the lens L22. A reduction in size of the second mirror49makes it possible to also reduce the size of the second mirror holding portion46.

The lens barrel40is covered with an external cover50, excluding a part thereof, such as the exit lens16. The external cover50has a first external cover50A, a second external cover50B, and a third external cover50C. The first external cover50A is an external cover that corresponds to the incidence-side end portion14A, the second external cover50B is an external cover that corresponds to the intermediate portion14B, and the third external cover50C is an external cover that corresponds to the exit-side end portion14C.

The first external cover50A covers the first lens barrel portion41, and constitutes an outer peripheral surface of the incidence-side end portion14A. The second external cover50B primarily covers the first mirror holding portion44and the second lens barrel portion42, and constitutes an outer peripheral surface of the intermediate portion14B. The third external cover50C primarily covers the second mirror holding portion46and the third lens barrel portion43, and constitutes an outer peripheral surface of the exit-side end portion14C.

As illustrated inFIGS.7and8, various types of actuators are disposed at an outer peripheral surface of the lens barrel40. Specifically, a zoom motor51is provided at an outer peripheral surface of the first lens barrel portion41, and a focus motor52is provided at an outer peripheral surface of the second mirror holding portion46. A solenoid53(also refer toFIG.6) is provided at an outer peripheral surface of the first mirror holding portion44, and a solenoid54(also refer toFIG.6) is provided at an outer peripheral surface of the second lens barrel portion42. The solenoid53constitutes the first rotation locking mechanism. The solenoid54constitutes the second rotation locking mechanism. The zoom motor51, the focus motor52, the solenoid53, and the solenoid54are examples of electrical driving units.

InFIG.6, the first lens barrel portion41includes an inner tube41A, an outer tube41B, a zoom-lens lens barrel41C, a cam tube41D, and a focus adjustment tube41E. A flange56that protrudes outward in a radial direction of the inner tube41A is provided at an incidence-side end portion at the first optical axis A1of the inner tube41A. The flange56nonrotatably fixes the inner tube41A with respect to the main body portion12. The outer tube41B is disposed on an exit side of the inner tube41A, and covers a part of an outer peripheral surface of the inner tube41A. The outer tube41B is mounted so as to be rotatable around the first optical axis A1with respect to the inner tube41A.

The first lens barrel portion41holds a first optical system L1. The first optical system L1is constituted by, for example, a lens FA, a lens group Z1, and a lens Z2, and is disposed on the first optical axis A1. The lens group Z1is constituted by a lens Z11and a lens Z12. The cam tube41D and the zoom-lens lens barrel41C are accommodated in the inner tube41A. The zoom-lens lens barrel41C has two groups of zoom lenses. The two groups of zoom lenses are constituted by the lens group Z1and the lens Z2.

A first cam groove (not illustrated) and a second cam groove (not illustrated) are formed in the cam tube41D. The first cam groove is a cam groove for moving the lens group Z1. The second cam groove is a cam groove for moving the lens Z2. A first cam pin (not illustrated) is provided at a lens holding frame of the lens group Z1. A second cam pin (not illustrated) is provided at a lens holding frame of the lens Z2. The first cam pin is inserted into the first cam groove, and the second cam pin is inserted into the second cam groove.

When the cam tube41D rotates around the first optical axis A1, the lens group Z1moves along the first cam groove and the first optical axis A1, and the lens Z2moves along the second cam groove and the first optical axis A1. In this way, when the lens group Z1and the lens Z2move along the first optical axis A1, the position of the lens group Z1on the first optical axis changes, the position of the lens Z2on the first optical axis A1changes, and the interval between the lens group Z1and the lens Z2changes. Therefore, zooming is performed.

The cam tube41D rotates as a result of driving of the zoom motor51. A cylindrical gear58is provided on an outer side of the inner tube41A. The gear58rotates around the inner tube41A due to the driving of the zoom motor51. A drive pin (not illustrated) for rotating the cam tube41D is provided at the gear58. When the gear58rotates, the drive pin also rotates in a peripheral direction of the inner tube41A, and the rotation causes the cam tube41D to rotate. An insertion groove (not illustrated) in which the drive pin is inserted is formed in the peripheral direction in the inner tube41A to prevent interference with the drive pin.

A fixed aperture stop St is provided between the lens Z11and the lens Z12in an inner portion of the zoom-lens lens barrel41C. The fixed aperture stop St narrows a light beam that is incident thereupon from the main body portion12. By providing the fixed aperture stop St in the zoom-lens lens barrel41C, it is possible to realize a telecentric optical system in which the size of an image in the center of an image formation surface and the size of the image in the vicinity do not differ regardless of an incidence height of the light beam.

The focus adjustment tube41E is mounted on the incidence-side end portion of the inner tube41A, and is rotatable around the first optical axis A1with respect to the inner tube41A. Threaded grooves are formed in an outer peripheral surface of an exit-side end portion of the focus adjustment tube41E and in an inner peripheral surface of the inner tube41A, and the threaded grooves mesh with each other. Since the inner tube41A is fixed with respect to the main body portion12, when the focus adjustment tube41E rotates with respect to the inner tube41A, the focus adjustment tube41E moves along the first optical axis A1by the action of the threads.

The focus adjustment tube41E holds the focus adjustment lens FA. By moving the lens FA along the first optical axis A1, a focus position of the entire system of the projection lens11and the position of the image formation panel32relative to each other are adjusted. When mounting the projection lens11onto the main body portion12, there is an individual difference in the mounting position of the projection lens11with respect to the image formation panel32. The focus adjustment tube41E is provided for making substantially the same the focus position of the entire system of the projection lens11and the position of the image formation panel32relative to each other by absorbing such an individual difference occurring at the time of manufacture.

A first rotation-position detection sensor59is provided at an outer peripheral surface of the outer tube41B. The first rotation-position detection sensor59detects the rotation position of the outer tube41B with respect to the inner tube41A.

The first mirror holding portion44is mounted on an exit-side end portion of the outer tube41B. Therefore, the rotation of the outer tube41B around the first optical axis A1with respect to the inner tube41A causes the first mirror holding portion44to rotate around the first optical axis A1. The first mirror holding portion44holds the first mirror48with a reflective surface of the first mirror48being oriented at an angle of 45° with respect to each of the first optical axis A1and the second optical axis A2. The first mirror48is a specular reflective type mirror in which a transparent member, such as glass, is coated with a reflective film.

The second lens barrel portion42includes an outer tube42A and the inner tube42B. An incidence-side end portion of the outer tube42A is mounted on the first mirror holding portion44. The inner tube42B is mounted so as to be rotatable around the second optical axis A2with respect to the outer tube42A.

The second lens barrel portion42holds a second optical system L2. The second optical system L2is constituted by, for example, a lens L21and a lens L22, and is disposed on the second optical axis A2. The outer tube42A holds the lens L21. The inner tube42B holds the lens L22.

In the present example, the second optical system L2functions as a relay lens. More specifically, the first optical system L1of the first lens barrel portion41forms an intermediate image in the first mirror holding portion44. The second optical system L2relays, with the intermediate image being a subject, a light beam that represents the intermediate image to the second mirror holding portion46and the third lens barrel portion43.

In the second lens barrel portion42, the second mirror holding portion46is mounted on an exit-side end portion of the inner tube42B. Therefore, rotation of the inner tube42B around the second optical axis A2with respect to the outer tube42A causes the second mirror holding portion46to rotate around the second optical axis A2.

A second rotation-position detection sensor60is provided at an outer peripheral surface of the outer tube42A. The second rotation-position detection sensor60detects the rotation position of the inner tube42B with respect to the outer tube42A.

The second mirror holding portion46holds the second mirror49with a reflective surface of the second mirror49being oriented at an angle of 45° with respect to each of the second optical axis A2and the third optical axis A3. Similarly to the first mirror48, the second mirror49is a specular reflective type mirror.

An exit-side end portion46A of the second mirror holding portion46constitutes the third lens barrel portion43. In addition to the end portion46A, the third lens barrel portion43includes a fixed tube43A, an exit-lens holding frame43B, and a focus-lens lens barrel43C.

The third lens barrel portion43holds a third optical system L3. The third optical system L3is constituted by, for example, a lens L31, a lens L32, and the exit lens16, and is disposed on the third optical axis A3. The end portion46A is a cylindrical portion whose center axis substantially coincides with the third optical axis A3, and functions as a lens holding frame that holds the lens L31.

The fixed tube43A is mounted on an exit-side of the end portion46A. The exit-lens holding frame43B is mounted on an exit-side end portion of the fixed tube43A. The fixed tube43A holds, on an inner peripheral side, the focus-lens lens barrel43C so as to be movable in a direction of the third optical axis A3. The focus-lens lens barrel43C holds the focus lens L32.

A gear62is provided at an outer periphery of the fixed tube43A. The gear62rotates in a peripheral direction of the fixed tube43A due to driving of the focus motor52. A threaded groove is formed in an inner peripheral surface of the gear62. A threaded groove is also formed in the outer peripheral surface of the fixed tube43A. The threaded groove in the inner peripheral surface of the gear62and the threaded groove in the outer peripheral surface of the fixed tube43A mesh with each other. Therefore, when the gear62rotates, the gear62moves in the direction of the third optical axis A3with respect to the fixed tube43A. A drive pin62A is provided at the gear62, and is inserted into the focus-lens lens barrel43C. Therefore, the movement of the gear62causes the focus-lens lens barrel43C to also move along the third optical axis A3. By the movement of the focus-lens lens barrel43C, as a focus position of the projection lens11, a focus position that is in accordance with the distance between the screen36and the projection lens11is adjusted.

Here, in the present example, the third optical axis A3is an example of an exit-side optical axis along which the light incident upon the projection lens11from the main body portion12exits, the second optical axis A2is an example of a first incidence-side optical axis that is disposed on an incidence side with respect to the third optical axis A3and that is bent with respect to the third optical axis A3, and the first optical axis A1is an example of a second incidence-side optical axis that is disposed on an incidence side with respect to the second optical axis A2and that is bent with respect to the second optical axis A2.

The third lens barrel portion43is an example of an exit-side lens barrel portion through which the exit-side optical axis extends. The second lens barrel portion42is an example of a first incidence-side lens barrel portion that is disposed on an incidence side with respect to the exit-side lens barrel portion and through which the first incidence-side optical axis extends. The first lens barrel portion41is an example of a second incidence-side lens barrel portion that is disposed on an incidence side with respect to the first incidence-side lens barrel portion and through which the second incidence-side optical axis extends.

In the second lens barrel portion42, the inner tube42B is an example of a first rotary tube that rotates around the first incidence-side optical axis (the second optical axis A2) as a result of rotating the third lens barrel portion43. The outer tube42A is an example of a first fixed tube on which the first rotary tube is mounted. In the first lens barrel portion41, the outer tube41B is an example of a second rotary tube that rotates around the second incidence-side optical axis (the first optical axis A1), and the inner tube41A is an example of a second fixed tube.

As illustrated inFIGS.7to9, a rotary portion64that is connected to one end of the inner tube42B of the second lens barrel portion42is provided at an incidence-side end portion of the second mirror holding portion46. By connecting the inner tube42B and the rotary portion64to each other, rotation of the third lens barrel portion43and the second mirror holding portion46around the second optical axis A2causes the inner tube42B to rotate. The rotary portion64has a flange shape whose diameter is larger than the diameter of the inner tube42B and that extends in a radial direction with respect to the inner tube42B.

At an exit-side end portion of the outer tube42A, a wide-width portion66whose diameter is larger than the diameter of the incidence-side end portion thereof is provided. As illustrated inFIG.6, an incidence-side surface64A of the rotary portion64and an exit-side end surface66A of the wide-width portion66are disposed so as to face each other in a direction of the second optical axis A2.

Four ball plungers68are provided at an exit-side surface64B of the rotary portion64. As described below, each ball plunger68is an example of a first pressing portion that presses the outer tube42A, which is a first fixed tube, in the direction of the second optical axis A2. The second mirror holding portion46is an example of a first connection frame that connects the third lens barrel portion43and the second lens barrel portion42to each other. Each ball plunger68, which is an example of a first pressing portion, is mounted on the surface64B of the rotary portion64, which is an example of an outer peripheral surface of the first connection frame.

Mounting holes69for mounting the ball plungers68are formed in the surface64B of the rotary portion64. Four mounting holes69are formed in correspondence with the number of ball plungers68. Outer peripheral surfaces around the axes of the ball plungers68are threaded. By engaging the threads with the mounting holes69, the ball plungers68are fixed to the rotary portion64by the action of the threads. The mounting positions of the ball plungers68in the direction of the second optical axis A2can be adjusted by the action of the threads.

As one example, the four mounting holes69are disposed at an interval of 90° in a peripheral direction around the second optical axis A2. By mounting the four ball plungers68in the respective mounting holes69, the four ball plungers68are disposed apart from each other at an interval of 90° in the peripheral direction around the second optical axis A2.

The surface66A of the wide-width portion66(also refer toFIGS.10and11) is disposed so as to face the ball plungers68in the direction of the second optical axis A2. The surface66A of the wide-width portion66is an example of a first press surface that is pressed by the ball plungers68. The ball plungers68are rotated by rotation of the third lens barrel portion43around the second optical axis A2. The surface66A of the wide-width portion66is pressed by the ball plungers68regardless of the rotation position of the third lens barrel portion43.

As illustrated inFIG.10, four fitting holes70to which end portions of the four ball plungers68corresponding thereto are fitted are formed in the surface66A. Each fitting hole70is an example of a first fitting hole. The four fitting holes70are disposed apart from each other at an interval of 90° in the peripheral direction around the second optical axis A2in correspondence with the four ball plungers68.

As illustrated inFIGS.11A and11B, as is well known, each ball plunger68has a spring68B that is provided in an inner portion of a main body and a ball68A that is provided at one end portion of the main body. Each ball68A is pressed by a pressing force of the spring68B in a direction in which the ball68A protrudes from the one end portion of the main body. When the third lens barrel portion43rotates around the second optical axis A2, the state of each ball plunger68is switched between a fitting state illustrated inFIG.11Ain which each ball plunger68is fitted to the fitting hole70and a move-out state illustrated inFIG.11Bin which each ball plunger68moves out of the fitting hole70.

InFIG.10, mounting holes73for mounting ball bearings72are formed in an outer peripheral surface of the inner tube42B (refer to, for example,FIG.9). Each ball bearing72is an example of a first protrusion portion that protrudes in a radial direction of the inner tube42B. As described below, each ball bearing72constitutes a first engaging portion that rotatably engages the inner tube42B with respect to the outer tube42A (refer to, for example,FIG.9). Each ball bearing72has a shaft portion and a head portion, and is a ball bearing with a shaft and whose head portion functions as a ball bearing. By fitting the shaft portion of each ball bearing72to its corresponding mounting hole73, each ball bearing72is fixed to the inner tube42B. With each ball bearing72being fixed to the inner tube42B, each ball bearing72protrudes in the radial direction of the inner tube42B.

Three ball bearings72are provided. The three ball bearings72are disposed apart from each other at an interval of 120° in the peripheral direction around the second optical axis A2in the inner tube42B (also refer toFIG.14). Insertion holes66B in which the three ball bearings72can be inserted are formed in an outer peripheral surface in the peripheral direction around the second optical axis A2in the wide-width portion66. The insertion holes66B are provided for allowing the ball bearings72to enter an inner portion of the outer tube42A from the outside of the outer tube42A with the inner tube42B being inserted in the outer tube42A.

As illustrated inFIG.12in addition toFIG.9, four ball plungers74are also provided in the outer tube41B, which is a second rotary tube, of the first lens barrel portion41. As described below, each ball plunger74is an example of a second pressing portion that presses the inner tube41A, which is a second fixed tube, in a direction of the first optical axis A1. The first mirror holding portion44is an example of a second connection frame that connects the second lens barrel portion42and the first lens barrel portion41to each other. The ball plungers74are mounted at the first mirror holding portion44, and are disposed in an inner portion of the first mirror holding portion44. The first mirror holding portion44is an example of a pressing-portion holding member that holds the second pressing portions. The first mirror holding portion44can be separated from the outer tube41B.

Similarly to the mounting holes69, mounting holes44A for mounting the ball plungers74are formed in the first mirror holding portion44. Four mounting holes44A are formed in correspondence with the number of ball plungers74. Similarly to the ball plungers68, outer peripheral surfaces around the axes of the ball plungers74are threaded. By engaging the threads with the mounting holes44A, the ball plungers74are fixed to the first mirror holding portion44by the action of the threads. The mounting positions of the ball plungers74in the direction of the first optical axis A1can be adjusted by the action of the threads.

As one example, similarly to the mounting holes69for the ball plungers68, the four mounting holes44A are disposed at an interval of 90° in a peripheral direction around the first optical axis A1. By mounting the four ball plungers74in the respective mounting holes44A, the four ball plungers74are disposed apart from each other at an interval of 90° in the peripheral direction around the first optical axis A1.

An exit-side end surface41A1of the inner tube41A is disposed so as to face the ball plungers74in the direction of the first optical axis A1. The end surface41A1is an example of a second press surface that is pressed by the ball plungers74. The ball plungers74rotate as a result of rotating the second lens barrel portion42around the first optical axis A1. The end surface41A1of the inner tube41A is pressed by the ball plungers74regardless of the rotation position of the second lens barrel portion42.

Four fitting holes76(refer toFIG.9) to which end portions of the four ball plungers74corresponding thereto are fitted are formed in the end surface41A1of the inner tube41A. Each fitting hole76is an example of a second fitting hole. The four fitting holes76are disposed apart from each other at an interval of 90° in the peripheral direction around the first optical axis A1in correspondence with the four ball plungers74.

When the second lens barrel portion42rotates around the first optical axis A1, a state of the four ball plungers74is switched between a fitting state in which the ball plungers74are fitted to the fitting holes76and a move-out state in which the ball plungers74move out of the fitting holes76. Such operations of the ball plungers74are similar to those of the ball plungers68illustrated inFIGS.11A and11B.

As illustrated inFIG.9, mounting holes41A2for mounting ball bearings78similar to the ball bearings72are formed in the outer peripheral surface of the inner tube41A. Each ball bearing78is an example of a second protrusion portion that protrudes from the inner tube41A. As described below, each ball bearing that functions as a second protrusion portion constitutes a second engaging portion that rotatably engages the outer tube41B with respect to the inner tube41A.

Similarly to the ball bearings72, three ball bearings78are provided. The three ball bearings78are disposed apart from each other at an interval of 120° in the peripheral direction around the first optical axis A1in the inner tube41A. Insertion holes41B1in which the three ball bearings78can be inserted are formed in an outer periphery in the peripheral direction around the second optical axis A2in the outer tube41B. The insertion holes41B1are provided for allowing the ball bearings78to enter an inner portion of the outer tube41B from the outside of the outer tube41B with the inner tube41A being inserted in the outer tube41B.

A pattern formation portion80(refer toFIGS.9and10) is provided on a portion of the outer peripheral surface of the inner tube42B that faces an inner peripheral surface of the outer tube42A with the inner tube42B being mounted on the outer tube42A. As described below, the pattern formation portion80and the second rotation-position detection sensor60constitute a second rotation-position detection mechanism.

As illustrated inFIG.10, a first conduction portion82is provided between the end surface66A of the wide-width portion66of the outer tube42A and the surface64A of the rotary portion64. The first conduction portion82realizes electrical conduction between a side of the outer tube42A and a side of the inner tube42B. For example, in the direction of the optical axis, the focus motor52is provided at the outer peripheral surface of the second mirror holding portion46on the side of the inner tube42B. On the other hand, on the side of the outer tube42A, for example, a power supply that supplies electrical power and a control board that sends a control signal to the focus motor52are provided in the main body portion12. The first conduction portion82is used for sending electrical power from the power supply and a control signal from the control board to the focus motor52. The first conduction portion82is constituted by a cableless-type conduction portion.

As illustrated inFIG.13, a connector83A is, for example, electrically connected to the first conduction portion82via a metal strip (not illustrated) or the like. The connector83A rotates as a result of rotating the inner tube42B around the second optical axis A2. The connector83A is electrically connected to the focus motor52via a cable86A.

As illustrated inFIG.10, at the rotary portion64of the second mirror holding portion46and the wide-width portion66of the outer tube42A, rotary electrodes82B and fixed electrodes82A are disposed on an outer side with respect to the ball plungers68. As a result, since it is possible to extend the cable86A from an outer side of the rotary portion64, interference with other members is reduced, and the focus motor52and the cable86A can be easily electrically connected to each other.

A connector83B is provided at the outer tube42A (also refer toFIG.9). The connector83B is, for example, electrically connected to the first conduction portion82via a metal strip (not illustrated) or the like. The connector83B is electrically connected to the power supply and the control board of the main body portion12via a cable86B.

InFIG.10, the first conduction portion82is constituted by one set of electrodes including the fixed electrodes82A that are provided at the outer tube42A and the rotary electrodes82B that are provided at the inner tube42B. The rotary electrodes82B are mounted on the rotary portion64connected to the inner tube42B, and are indirectly provided with respect to the inner tube42B. Therefore, the rotary electrodes82B rotate as a result of rotating the inner tube42B. The fixed electrodes82A are mounted on the surface66A of the wide-width portion66of the outer tube42A, and are directly provided with respect to the outer tube42A. Since the outer tube42A does not rotate around the second optical axis A2, the fixed electrodes82A also do not rotate around the second optical axis A2.

The fixed electrodes82A are planar electrodes that extend in the peripheral direction around the second optical axis A2. More specifically, the planar electrodes are ring-shaped electrodes. The rotary electrodes82B are partial contact electrodes that partially contact the fixed electrodes82A. Four rotary electrodes82B are provided, and are disposed apart from each other in a peripheral direction of the ring-shaped fixed electrodes82A.

The four rotary electrodes82B are mounted on a ring-shaped mount plate84. The mount plate84is mounted on the rotary portion64. Therefore, the four rotary electrodes82B are indirectly provided at the inner tube42B, and rotate as a result of rotating the inner tube42B. The connector83A is also mounted on the mount plate84. The fixed electrodes82A and the rotary electrodes82B while being kept in a contact state rotate relative to each other. That is, the fixed electrodes82A and the rotary electrodes82B normally in contact with each other rotate relative to each other.

In a radial direction of the outer tube42A and the inner tube42B, the first conduction portion82is disposed on an outer side with respect to the ball plungers68.

As illustrated inFIG.14in addition toFIG.10, each rotary electrode82B is formed from a conductive strip82B1that is elastic. Each strip82B1has the shape of a belt. At an intermediate portion in a longitudinal direction, both ends of each strip82B1are bent in a direction of the fixed electrodes82A. Both of the ends of the strips82B1in the longitudinal direction contact the fixed electrodes82A.

A distance D1between the mount plate84on which the strips82B1are mounted and the fixed electrodes82A is narrower than a thickness at which external force is not applied to the strips82B1. Therefore, the strips82B1, in an elastically deformed state, are in contact with the fixed electrodes82A. Due to the action of elastic forces, both of the ends of the strips82B1are pressed toward the fixed electrodes82A. Therefore, the rotary electrodes82B press-contact the fixed electrodes82A.

As illustrated inFIG.10, each rotary electrode82B has a set of two strips82B1to which electrical signals that differ from each other are input. Two fixed electrodes82A are also provided, and the two fixed electrodes82A contact the strips82B1. These are used as electrodes for supplying electrical power and for sending control signals.

As illustrated inFIG.13, in the second lens barrel portion42, the first conduction portion82for realizing electrical conduction between the side of the inner tube42B, which is a first rotary tube, and the side of the outer tube42A, which is a first fixed tube, is a cableless-type conduction portion. In contrast, in the first lens barrel portion41, a second conduction portion for realizing electrical conduction between a side of the outer tube41B, which is a second rotary tube, and a side of the inner tube41A, which is a second fixed tube, is a cable-type conduction portion that uses the cable86B.

As illustrated inFIGS.15and17, in the second lens barrel portion42, an accommodation groove88is formed in the inner peripheral surface of the outer tube42A. As illustrated inFIG.16A, in the inner peripheral surface of the outer tube42A, the accommodation groove88is formed in the entire circumference in the peripheral direction around the second optical axis A2. The accommodation groove88can accommodate at least a part of each ball bearing72. The inner tube42B rotates with respect to the outer tube42A with the ball bearings72protruding from the inner tube42B being accommodated in the accommodation groove88.

As illustrated inFIG.16B, an abutment surface88A that abuts upon the ball bearings72is formed at one surface on an exit side in the direction of the second optical axis A2in the accommodation groove88. The ball bearings72and the abutment surface88A are disposed so as to face each other in the direction of the second optical axis A2. The abutment surface88A is an example of a first abutment surface. The ball bearings72and the abutment surface88A constitute the first engaging portions.

OfFIGS.17A and17B, as illustrated inFIG.17A, the ball plungers68are provided at the rotary portion64. As illustrated inFIG.17B, the ball plungers68press the surface66A of the outer tube42A in the direction of the second optical axis A2. By the pressing, the ball bearings72that are provided at the inner tube42B are pressed against the abutment surface88A that is formed at the accommodation groove88of the outer tube42A. By pressing the ball bearings72against the abutment surface88A, backlash between the ball bearings72and the accommodation groove88is suppressed.

FIG.18is a schematic view clearly illustrating the functions of the ball bearings72and the ball plungers68by ignoring the actual relative positions between the plurality of ball bearings72and the plurality of ball plungers68.

As illustrated inFIG.18, each ball plunger68has a top portion68C. Each top portion68C is a portion that is farthest from the end surface66A in an outer peripheral portion of its corresponding ball plunger68. An interval D2between the rotary portion64, at which the ball plungers68are mounted, and the ball bearings72is fixed. The mounting positions of the ball plungers68with respect to the rotary portion64can be adjusted by the action of the threads of the ball plungers68. Therefore, the larger the amount of insertion of the ball plungers68is with respect to the rotary portion64, the narrower an interval D3between the top portions68C of the ball plungers68and the ball bearings72is, whereas the smaller the amount of insertion is, the wider the interval D3is.

The narrower the interval D3is, the stronger the pressing force of the ball bearings72is with respect to the abutment surface88A. The stronger the pressing force is, the more the backlash of the inner tube42B is suppressed with respect to the outer tube42A.

The stronger the pressing force is, the larger the friction force between the ball bearings72and the abutment surface88A and the friction force between the ball plungers68and the surface66A are. Due to these friction forces, a rotation restriction force that restricts rotation of the inner tube42B, that is, a rotation restriction force that restricts rotation of the exit-side end portion14C around the second optical axis A2is generated. When the rotation restriction force is large, an operation force for rotating the exit-side end portion14C is also large. In contrast, when the rotation restriction force is small, the exit-side end portion14C may rotate accidentally. Considering such circumstances, a rotation restriction force that is generated based on the pressing force of the ball plungers68is set.

In the present example, the rotation restriction force is set as follows. First, as illustrated inFIGS.19and20, when the direction of the second optical axis A2is a horizontal direction H that is orthogonal to a gravitation direction G, a rotation force that rotates the exit-side end portion14C around the second optical axis A2by the action of gravitation is T1. The rotation force T1 is a rotation force that acts upon the position of a center of gravity O1of the exit-side end portion14C. The rotation force T1 corresponds to a rotation force that rotates the third lens barrel portion43around the second optical axis A2.

When the direction of the second optical axis A2is the horizontal direction H, the rotation restriction force that restricts the rotation of the exit-side end portion14C around the second optical axis A2and that is generated based on the pressing force of the ball plungers68, which are first pressing portions, is F1. The rotation restriction force F1 corresponds to a rotation restriction force that restricts the rotation of the third lens barrel portion43around the second optical axis A2.

The relationship between the rotation force T1 and the rotation restriction force F1 is set so as to satisfy the following Formula (1):
F1>T1  Formula (1)

When the relationship between the rotation force T1 and the rotation restriction force F1 satisfies Formula (1), even when the orientations of the projection lens11are the orientations illustrated inFIGS.19and20, the exiting direction of light of the exit-side end portion14C is not rotated by the action of gravitation.

Even in the first lens barrel portion41, second engaging portions that are similar to the first engaging portions of the second lens barrel portion42are provided. The second engaging portions are constituted by the ball bearings78corresponding to the second protrusion portions (refer toFIG.9) and a second abutment surface (not illustrated) that is disposed so as to face the ball bearings78in the direction of the first optical axis A1. The second abutment surface is formed at an inner peripheral surface of the outer tube41B and at one surface of an inner portion of an accommodation groove that accommodates the ball bearings78. Since the structures of the accommodation groove and the second abutment surface are the same as those of the accommodation groove88and the first abutment surface88A of the second lens barrel portion42, they are not illustrated and described.

As in the second lens barrel portion42, even in the first lens barrel portion41, the stronger the pressing force of the ball plungers74, which are second pressing portions, is, the more backlash of the outer tube41B is suppressed with respect to the inner tube41A.

The stronger the pressing force of the ball plungers74is, the larger the friction force between the ball bearings78and the abutment surface (not illustrated) and the friction force between the ball plungers74and the end surface41A1(refer toFIG.12) are. Due to these friction forces, a rotation restriction force that restricts rotation of the outer tube41B, that is, a rotation restriction force that restricts rotation of the intermediate portion14B and the exit-side end portion14C around the first optical axis A1is generated. When the rotation restriction force is large, an operation force for rotating the intermediate portion14B and the exit-side end portion14C is also large. In contrast, when the rotation restriction force is small, the intermediate portion14B and the exit-side end portion14C may rotate accidentally. Considering such circumstances, a rotation restriction force that is generated based on the pressing force of the ball plungers74is set.

In the present example, the rotation restriction force is set as follows. As illustrated inFIG.21, first, when the direction of the first optical axis A1is a horizontal direction H that is orthogonal to a gravitation direction G, a rotation force that rotates the intermediate portion14B and the exit-side end portion14C around the first optical axis A1by the action of gravitation is T2. The rotation force T2 is a rotation force that acts upon the position of a center of gravity O2of the intermediate portion14B and the exit-side end portion14C. The rotation force T2 corresponds to a rotation force that rotates the second lens barrel portion42and the third lens barrel portion43around the first optical axis A1.

When the direction of the first optical axis A1is the horizontal direction H, the rotation restriction force that restricts the rotation of the intermediate portion14B and the exit-side end portion14C around the first optical axis A1and that is generated based on the pressing force of the ball plungers74, which are second pressing portions, is F2. The rotation restriction force F2 corresponds to a rotation restriction force that restricts the rotation of the second lens barrel portion42and the third lens barrel portion43around the first optical axis A1.

The relationship between the rotation force T2 and the rotation restriction force F2 is set so as to satisfy the following Formula (2):
F2>T2  Formula (2).

When the relationship between the rotation force T2 and the rotation restriction force F2 satisfies Formula (2), even when the orientation of the projection lens11is the orientation illustrated inFIG.21, the exiting direction of light of the intermediate portion14B and the exit-side end portion14C is not rotated by the action of gravitation.

Since the rotation force T2 is larger than the rotation force T1 due to the influence of the weight of the intermediate portion14B, the relationship between the rotation restriction force F1 and the rotation restriction force F2 is set so as to satisfy the following Formula (3):
F1<F2  Formula (3).

As illustrated inFIGS.22to24, the second rotation-position detection mechanism that is constituted by the pattern formation portion80and the second rotation-position detection sensor60detects the rotation position of the inner tube42B around the second optical axis A2with respect to the outer tube42A in the second lens barrel portion42. When the inner tube42B rotates, the third lens barrel portion43through which the third optical axis A3extends rotates around the second optical axis A2. When, as with the projection lens11, a projection lens includes a bending optical system having a plurality of optical axes that rotate with respect to each other, a display orientation of an image P that is projected onto the screen36changes in accordance with the rotation of the optical axes. The second rotation-position detection mechanism detects the rotation position of the inner tube42B and sends the detected rotation position to the control board of the main body portion12.

As illustrated inFIG.23, for example, a plurality of patterns that differ are formed at each rotation position of the inner tube42B at the pattern formation portion80. The second rotation-position detection sensor60is, for example, a photosensor that optically reads the plurality of patterns.

For example, in addition to four patterns indicating four rotation positions P1to P4that are set at an interval of 90°, patterns indicating two rotation positions each between corresponding ones of the rotation positions P1to P4are formed at the pattern formation portion80. That is, a total of 12 different patterns are formed at the pattern formation portion80. The second rotation-position detection sensor60optically reads the 12 different patterns, and sends detection signals indicating the rotation positions that are in accordance with the respective patterns to the control board of the main body portion12. Two patterns exist between the rotation position P1and the rotation position P2, and, due to these patterns, the second rotation-position detection sensor60can detect the current rotation position for every 45°.

FIGS.24A to24Ceach illustrate a rotation position of the inner tube42B (refer toFIG.22) that rotates together with the second mirror holding portion46. InFIGS.24A to24C, the rotation position of the inner tube42B illustrated inFIG.24Ais an initial rotation position P1, and the rotation position illustrated inFIG.24Cis a rotation position P4after rotation by 90° in a counterclockwise direction from the rotation position P1. In the state illustrated inFIG.24A, the second rotation-position detection mechanism sends a detection signal indicating the rotation position P1to the main body portion12. Then, as illustrated inFIG.24B, when the inner tube42B starts to rotate in the counterclockwise direction from the rotation position P1, the second rotation-position detection mechanism sends a detection signal that is in accordance with a rotation position between the rotation position P1and the rotation position P4. When the inner tube42B rotates by 90° in the counterclockwise direction, the second rotation-position detection mechanism sends a detection signal indicating the rotation position P4. In the present embodiment, the positions from the rotation position P1to the rotation position P4correspond to the positions at which the ball plungers68are inserted into the fitting holes70. Therefore, at the rotation positions P1to P4, the projection lens11can stably project an image. In other words, the second rotation-position detection mechanism of the present embodiment can detect the positions at which the ball plungers68are inserted into the fitting holes70and the positions at which the ball plungers68are not inserted into the fitting holes70.

The control board controls the image formation unit26based on a received rotation position. Therefore, a display orientation of the image P is switched to a suitable orientation.

Note that a first rotation-position detection mechanism that detects the rotation position of the outer tube41B with respect to the inner tube41A is provided at the first lens barrel portion41. The first rotation-position detection mechanism is constituted by the first rotation-position detection sensor59that is provided at the outer tube41B and a pattern formation portion that is similar to the pattern formation portion80and that is provided at the inner tube41A.

The first rotation-position detection mechanism and the second rotation-position detection mechanism detect the rotation position of the second lens barrel portion42and the rotation position of the third lens barrel portion43. To be exact, the control board of the main body portion12switches the display orientation of the image P in accordance with a combination of these two rotation positions.

The operations of the structure above are described below. First, in the accommodated state of the projection lens11, since the projection lens11fits in the accommodation portion (recessed portion)12C, as illustrated inFIG.1, in plan view, the projector10has a substantially rectangular parallelepiped shape as a whole. Therefore, in the accommodated state, the projector10is easily carried and accommodated.

When the projector10is used, depending upon use situations, the projector10is set at a use location in the horizontally-placed orientation illustrated inFIG.2or the vertically-placed orientation illustrated inFIG.3. In the projection lens11, by rotating the exit-side end portion14C and the intermediate portion14B around the first optical axis A1, the exit lens16is exposed to the outside. Further, by rotating the exit-side end portion14C around the second optical axis A2, the projection direction of the exit lens16is changed.

When the exit-side end portion14C is rotated around the second optical axis A2, the third lens barrel portion43in the exit-side end portion14C rotates around the second optical axis A2. The inner tube42B rotates around the second optical axis A2as a result of rotating the third lens barrel portion43. In the second lens barrel portion42, the inner tube42B and the outer tube42A include the ball bearings72, which are examples of first protrusion portions, and the abutment surface88A, which is an example of a first abutment surface (refer toFIGS.16A and16B). The ball plungers68, which are examples of first pressing portions, press the outer tube42A in the direction of the second optical axis A2, and the ball bearings72press against the abutment surface88A. Therefore, the inner tube42B rotates with respect to the outer tube42A with backlash suppressed.

Consequently, it is possible to suppress optical-axis shifts caused by the rotation of the inner tube42B, which is a first rotary tube, around the second optical axis A2.

Since the ball bearings72are used as examples of first protrusion portions, the friction force between the first protrusion portions and the first abutment surface is reduced. Therefore, compared with when the ball bearings72are not used, the inner tube42B, which is an example of a first rotary tube, can be smoothly rotated while optical-axis shifts are suppressed.

When the third lens barrel portion43rotates around the second optical axis A2, the state of each ball plunger68is switched between the fitting state illustrated inFIG.11Ain which each ball plunger68is fitted to the fitting hole70and the move-out state illustrated inFIG.11Bin which each ball plunger68moves out of the fitting hole70.

When the states of the ball plungers68have been changed from the move-out state to the fitting state by switching between the fitting state and the move-out state of the ball plungers68, a user senses a click feeling via a tactile feel and/or sound, as a result of which it is possible to detect a rotation position determined at the fitting holes70. The fitting holes70are disposed at an interval of 90°. Therefore, the user can detect the four rotation positions corresponding to four display orientations of the image P that have been preset.

Since the ball plungers68, which are examples of first pressing portions, that are fitted to the fitting holes70are used, elastic deformation of the springs68B makes it possible to smoothly switch between the fitting state and the move-out state.

Since the ball plungers68are provided at the outer peripheral surface of the second mirror holding portion46, this is convenient in terms of removing them at the time of maintenance.

A plurality of the ball plungers68, which are examples of first pressing portions, are provided. Therefore, the inner tube42B, which is an example of a first rotary tube, can rotate stably. At least three ball plungers68are provided. As described above, three ball bearings72, which are examples of first pressing portions, are provided and are disposed apart from each other at equal intervals of 120° in the peripheral direction around the second optical axis A2(refer toFIGS.16A and16B). Since the outer tube42A and the inner tube42B are supported at three points by the three ball bearings72, the inner tube42B can be rotated more stably. Similarly to the ball bearings72, three ball bearings78, which are examples of second pressing portions, are provided, and are disposed apart from each other at equal intervals of 120° in the peripheral direction around the first optical axis A1. Therefore, the same effect as that provided by the ball bearings72is provided.

As illustrated inFIGS.19and20, when the second optical axis A2is the horizontal direction H, the rotation restriction force F1 that restricts the rotation of the third lens barrel portion43, which is an example of an exit-side lens barrel portion, is larger than the rotation force T1 that rotates the third lens barrel portion43around the second optical axis A2by the action of gravitation. Therefore, even in the state illustrated inFIG.19, accidental rotation of the second lens barrel portion42is suppressed.

In the first lens barrel portion41, the outer tube41B, which is an example of a second rotary tube, rotates around the first optical axis A1with respect to the inner tube41A, which is an example of a second fixed tube. Even the first lens barrel portion41includes the ball bearings78.

Therefore, it is possible to suppress optical-axis shifts caused by the rotation of the outer tube41B, which is an example of a second rotary tube, around the first optical axis A1.

As illustrated inFIG.21, when the second optical axis A2is the horizontal direction H, the rotation restriction force F2 that restricts the rotation of the third lens barrel portion43, which is an example of an exit-side lens barrel portion, and the second lens barrel portion42is larger than the rotation force T2 that rotates the third lens barrel portion43and the second lens barrel portion42around the first optical axis A1by the action of gravitation. Therefore, even in the state illustrated inFIG.21, accidental rotation of the third lens barrel portion43and the second lens barrel portion42is suppressed.

Further, the rotation restriction force F1 is smaller than the rotation restriction force F2. The relationship between the magnitude of the rotation restriction force F1 and the magnitude of the rotation restriction force F2 is set in accordance with the rotation force T1 and the rotation force T2. Therefore, the rotation restriction force F1 of the third lens barrel portion43does not become excessively large.

The ball bearings72, which are examples of first protrusion portions, are provided at the inner tube42B, which is an example of a first rotary tube. The abutment surface88A is formed at one surface of the accommodation groove88that is formed in the inner peripheral surface of the outer tube42A, which is an example of a first fixed tube. Therefore, assembly is facilitated compared with when the ball bearings72are provided at the inner peripheral surface of the outer tube42A and the accommodation groove88is formed at the outer peripheral surface of the inner tube42B.

This is because, when the ball bearings72are provided at the inner peripheral surface of the outer tube42A, the head portion of each ball bearing72faces inward in a radial direction of the outer tube42A. Note that the ball bearings72may be provided at the outer tube42A.

InFIGS.24A to24C, the number of ball plungers68and the number of fitting holes70are the same. However, the number of fitting holes70may be less than the number of ball plungers68. In a specific example, the number of ball plungers68may be four, and the number of fitting holes70may be two. In this case, at least two ball plungers68are not fitted to the fitting holes70(state inFIG.11B). When the ball plungers68are not fitted to the fitting holes70as illustrated inFIG.11B, compared with when the ball plungers68are fitted to the fitting holes70as illustrated inFIG.11A, the springs68B strongly press the balls68A, as a result of which the rotation restriction force is increased. In other words, when the projection lens11includes at least one or more fitting holes70and a plurality of ball plungers68, and the number of fitting holes is less than the number of ball plungers68, the rotation restriction force is increased compared with when the number of fitting holes70and the number of ball plungers68are the same.

The plurality of ball plungers may include two or more types of ball plungers whose pressing forces differ from each other.

For example, as illustrated inFIG.25, among the plurality of ball plungers74that are provided at the first lens barrel portion41, first ball plungers74A having a relatively large pressing force and second ball plungers74B having a relatively small pressing force may be provided. When the direction of the second optical axis A2is the gravitation direction G, the first ball plungers74A are disposed on an exit side. The second ball plungers74B are disposed on an incidence side.

The orientation of the projection lens11illustrated inFIG.25is the orientation illustrated inFIG.4. When such a structure is used, it is possible to increase a rotation restriction force F3 that is generated based on the pressing force. When the rotation restriction force F3 is large, even if a rotation force T3 that rotates the projection lens11around the first optical axis A1is applied to the projection lens11, the projection lens11is further suppressed from accidentally falling sideways. In this way, when the pressing forces of the plurality of ball plungers differ from each other, an advantageous effect may be provided. This is because, in this case, when the pressing force of the second ball plungers74B is also large, the rotation restriction force when the intermediate portion14B is rotated with respect to the incidence-side end portion14A may become excessively strong.

In the present example, the first pressing portions are described as pressing the first press surface facing the first pressing portions in the direction of the second optical axis A2. When the first pressing portions are provided primarily for the purpose of causing a user to sense a click feel instead of suppressing backlash of the first rotary tube and the first fixed tube, a pressing direction of the first pressing portions need not be parallel to the second optical axis A2. For example, with a side surface of the first rotary tube and a side surface of the first fixed tube in the peripheral direction around the second optical axis A2being press surfaces, the first pressing portions that press the first press surfaces from a direction orthogonal to the second optical axis A2may be provided.

The projection lens11of the present example includes the first conduction portion82having the fixed electrodes82A that are provided at the outer tube42A, which is an example of a first fixed tube, and the rotary electrodes82B that are provided at the inner tube42B, which is an example of a first rotary tube. Therefore, in the projection lens in which electrical conduction is required on the side of the first rotary tube and on the side of the first fixed tube, even if the rotatable range of the first rotary tube is 360° or greater, there is no concern about a cable being twisted.

As illustrated inFIG.10, the fixed electrodes82A are ring-shaped electrodes, the rotary electrodes82B are partial contact electrodes that partially contact the ring-shaped electrodes, and the fixed electrodes82A and the rotary electrodes82B while being kept in a contact state rotate relative to each other. In this way, since the planar electrodes have a ring shape not having a cut portion, the fixed electrodes82A and the rotary electrodes82B are normally in contact with each other. Therefore, compared with when they are repeatedly brought into and out of contact with each other, the state of contact is stabilized. However, the fixed electrodes82A may be electrodes that are partially formed instead of electrodes that are provided in the form of a ring.

As illustrated inFIG.14, since the rotary electrodes82B, which are examples of partial contact electrodes, are in contact with the fixed electrodes82A, which are examples of ring-shaped electrodes, in an elastically deformed state, the state of contact becomes more stable. Each rotary electrode82B, which is an example of a partial contact electrode, is such that, at the intermediate portion of the belt-shaped strip82B1, both ends of the strip82B1are bent in the direction of the ring-shaped electrodes, and both of the ends are in contact with the ring-shaped electrodes. Therefore, the state of contact becomes more stable.

There are a plurality of partial contact electrodes, and the plurality of partial contact electrodes are disposed apart from each other in the peripheral direction of the ring-shaped electrodes. Therefore, the state of contact becomes more stable.

In the radial direction of the outer tube42A and the inner tube42B, the first conduction portion82is disposed on the outer side with respect to the ball plungers68. Therefore, a cable is easily routed.

The ball plungers74are mounted on the first mirror holding portion44, and are disposed in the inner portion of the first mirror holding portion44. The first mirror holding portion44can be separated from the outer tube41B. Therefore, since the ball plungers74are exposed by separating the first mirror holding portion44and the outer tube41B from each other, the ball plungers74are easily replaced and repaired.

In the first lens barrel portion41, a cable-type conduction portion that uses the cable86B is provided as a second conduction portion for realizing electrical conduction on the side of the outer tube41B, which is an example of a second rotary tube, and on the side of the inner tube41A, which is an example of a second fixed tube.

In the first lens barrel portion41, the rotatable range of the outer tube41B, which is a second rotary tube, is 180°, and is less than 360°. In contrast, in the second lens barrel portion42, the rotatable range of the inner tube42B, which is a first rotary tube, is 360° or greater. When the rotatable range of the rotary tube is less than 360°, there is less concern about a cable being twisted than when the rotatable range is 360° or greater.

A cableless-type conduction portion constituted by the fixed electrodes82A and the rotary electrodes82B as with the first conduction portion82costs more than the cable-type second conduction portion. Therefore, in the first lens barrel portion41in which there is little concern about a cable being twisted, it is possible to ensure a highly reliable conduction and to suppress costs by using a cable type.

Note that, although, as the cableless-type conduction portion, the conduction portion having the fixed electrodes82A and the rotary electrodes82B has been described as an example, a non-contact power-feeding type may also be used as the cableless-type conduction portion. Examples of the noncontact power-feeding type include a type that utilizes electromagnetic induction and a type that utilizes magnetic resonance, and either of these types may be used.

As disclosed in JP2001-203022A, the fixed electrodes82A or the rotary electrodes82B may be elastic conductive portions that are elastically deformed (for example, spring connectors). On the other hand, a conductive projection portion in which a projection is provided at a cylinder portion and a surface of the projection is provided with a conductive film may be provided. Therefore, by rotating the second rotary tube, the conductive projection portion presses the elastic conductive portion at a particular rotation position. Due to the pressing force and the elastic force of elastic members (for example, springs) of the elastic conductive portion, the elastic conductive portion and the conductive projection portion are brought into close contact with each other and are brought into an electrical conduction state.

Although, in the embodiment above, a projection lens having three optical axes formed by bending an optical axis twice has been described as an example, the technology of the present disclosure may be applied to a projection lens having two optical axes formed by bending an optical axis once. The technology of the present disclosure may also be applied to a projection lens having four or more optical axes. When a projection lens having four or more optical axes is used, among the four or more optical axes, the optical axis existing relatively on the exit side is an exit-side optical axis, and the optical axis just in front of the incidence side with respect to the exit-side optical axis is a first incidence-side optical axis.

Note that, although, in the example above, motors and solenoids are given as examples of the electrical driving units51to54, other mechanisms may be used as long as they are components that perform driving by using electricity. For example, as described in JP2017-142726A, the projector10, which is a projection device, may include an electronic pen that is capable of writing, for example, characters on a projection surface. In this case, the electrical driving units may be driving units of an image pickup element that captures emitted light produced as a result of writing with the electronic pen.

As the image formation panel32corresponding to an electro-optical element, instead of a DMD, a transmission-type image formation panel using a LCD may be used. In addition, instead of a DMD, a panel using a self-luminous element, such as a LED (light emitting diode) and/or an organic EL (electro luminescence), may be used. As the reflective portion, instead of a specular reflective type mirror, a total reflective type mirror may be used.

In the example above, although the use of a laser light source as the light source34is given as an example, the light source34is not limited thereto, and a mercury lamp and/or a LED may also be used as the light source34. In the example above, although a blue laser light source and a yellow fluorescent body are used, instead of the yellow fluorescent body, a green fluorescent body and a red fluorescent body may be used. In addition, instead of the yellow fluorescent body, a green laser light source and a red laser light source may be used.

In the present specification, “A and/or B” means the same as “at least one of A or B”. That is, “A and/or B” may mean only A, only B, or a combination of A and B. In the present specification, the meaning of “A and/or B” also similarly applies to expressions in which three or more things are connected by “and/or”.

All documents, patent applications, and technical standards that are described in the present specification are incorporated by way of reference in the present specification to the same extent as when each of the documents, patent applications, and technical standards are specifically and individually described as being incorporated herein by way of reference.

From the descriptions above, it is possible to understand the description of a projection lens that is described in the appendix below.

A projection lens that is to be mounted on a housing of a projection device having an electro-optical element includes

a bending optical system that includes at least two optical axes, the two optical axes being an exit-side optical axis along which light incident from the housing exits and a first incidence-side optical axis that is disposed on an incidence side with respect to the exit-side optical axis and that is bent with respect to the exit-side optical axis;

an exit-side lens barrel portion that accommodates an exit-side optical system having the exit-side optical axis and that rotates around the first incidence-side optical axis;

a first incidence-side lens barrel portion that is disposed on an incidence side with respect to the exit-side lens barrel portion and through which the first incidence-side optical axis extends, the first incidence-side lens barrel portion having a first rotary tube and a first fixed tube, the first rotary tube rotating around the first incidence-side optical axis as a result of rotating the exit-side lens barrel portion, the first rotary tube being rotatably mounted at the first fixed tube;

a first protrusion portion that is provided at one of the first rotary tube and the first fixed tube and that protrudes from the one of the first rotary tube and the first fixed tube;

a first abutment surface that is provided at the other of the first rotary tube and the first fixed tube and that faces and abuts upon the first protrusion portion in a direction of the first incidence-side optical axis; and

a first pressing portion that presses the first protrusion portion against the first abutment surface by pressing at least one of the first rotary tube or the first fixed tube in the direction of the first incidence-side optical axis,

wherein the first pressing portion and the first protrusion portion face each other with the first abutment surface in between in the direction of the first incidence-side optical axis.