JP2014010273A - Projection optical system and projector with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection optical system able to restrict adverse effect of heat generated by blocking light beams in a diaphragm, when used in a projector that enables image formation in which a slenderness ratio is adjusted by switching an aspect ratio, and to provide a projector incorporating the projection optical system.SOLUTION: An anamorphic optical system is employed, which has powers differing between the adjustment direction of a liquid crystal panel 18G whose second group 40 is an optical modulation element and the other directions of it. This enables the conversion of an aspect ratio, which is the ratio of width to height. Additionally, a diaphragm 70 is arranged between a first group 30, which is a magnifying optical system, and the second group 40, which is the anamorphic optical system. Thus, the diaphragm 70 can be cooled relatively easily. Also, the adverse effect of heat generated by blocking light beams on an optical member, as a result of the heat being transmitted to an optical member located in the vicinity of the diaphragm 70.

Description

  The present invention relates to a projection optical system capable of switching the aspect ratio of a projected image and a projector including the same.

  As a converter for converting an aspect ratio used in a projection optical system of a projector, there is a front-arranged converter that is disposed so as to be able to advance and retreat in front of the original projection optical system, that is, in front of the image side.

  However, this type of converter is provided as an external optical unit that is independent from the projector main body, which increases the size of the projector, complicates the adjustment of the entire projection optical system including the converter, or significantly deteriorates the image. Let

  It should be noted that the rear-arrangement type that is detachably arranged on the image side of the imaging optical system as an aspect ratio conversion converter or anamorphic imaging system used in an imaging optical system such as a camera, not a projection optical system of a projector There is a relay system (see Patent Documents 1 and 2). For example, the relay system of Patent Document 2 is composed of a first group, a second group, and a third group. Of these, the second group in the center is an anamorphic converter, and is between the first group and the third group. It can be inserted and removed.

  However, the technique disclosed in Patent Document 1 and the like relates to an imaging optical system, and if this is used as it is in a projection optical system, various restrictions may occur. For example, in a projection optical system of a projector, light emitted from a light source of the projector is uniformly applied to an image display element such as a liquid crystal panel, and this is enlarged and projected by the projection optical system. Inside, some light is kicked (blocked). Further, some projectors for cinema realize high contrast by limiting the spread of light beams by installing a movable diaphragm in the projection optical system. Adjusting the movable diaphragm to greatly limit the amount of light increases the thermal energy generated by converting the light energy, and that thermal energy is transmitted to the lens and lens frame, especially in the vicinity of the movable diaphragm. May have a significant impact. Such an influence of thermal energy is not always sufficiently considered in the imaging system.

JP 2005-3000928 A Special table 2008-511018 gazette

  The present invention incorporates a projection optical system capable of suppressing the influence of heat generated by shielding light rays at a stop when applied to a projector capable of forming an image with an adjusted aspect ratio by switching an aspect ratio, and the same. The object is to provide a projector.

  In order to solve the above-described problems and achieve the object, the projection optical system according to the present invention provides: (a) When an image of a light modulation element is enlarged and projected on a projection surface, A projection optical system in which an aspect ratio and an aspect ratio of an image projected on a projection surface are different, and (b) a first group that is an enlargement optical system in order from the projection surface side; An adjustment optical element having at least one optical element having a rotationally asymmetric surface with respect to the optical axis and having different power in an adjustment direction for performing conversion adjustment by compression or extension and in another direction; A second group that performs the conversion adjustment with at least one of the vertical direction and the horizontal direction of the light modulation element as an adjustment direction; a third group that includes a correction optical element having a rotationally symmetric surface with respect to the optical axis; (C) light is partially blocked between the first group and the second group Ri has been placed.

  In the projection optical system, the first group is a magnifying optical system that performs magnified projection, the second group performs aspect ratio conversion by compression or expansion, and the third group is spread and emitted from the light source side. It is a correction optical element that corrects the angle in the direction of narrowing the light. Further, in this projection optical system, a diaphragm that blocks light rays is disposed between the first group that is an enlargement optical system and the second group that includes an adjustment optical element that performs conversion adjustment by compression or expansion. In general, the magnifying optical system is composed of a circular lens or the like, while the adjustment optical element that performs conversion adjustment by compression or expansion is composed of, for example, a cylindrical lens and has a rectangular shape. For this reason, the shape of the lens frame to which the optical member is assembled is generally different between the first group side and the second group side. Even when the lens frame is integrated, it is easy to secure a space between portions corresponding to each group. Therefore, the diaphragm arranged between the first group and the second group can be easily cooled compared to the diaphragm arranged in the first group, which is an expansion optical system, and the heat generated by the light shielding is near the diaphragm. It is possible to suppress the influence transmitted to the optical member disposed on the optical member.

  According to a specific aspect of the present invention, the diaphragm is a movable diaphragm capable of adjusting the light shielding amount. In this case, for example, a high contrast image can be formed by increasing the light shielding amount, or a bright image can be formed by reducing the light shielding amount.

  According to another aspect of the present invention, the first group is a zoom optical system. In this case, the projection magnification can be changed in the first group. Further, since the position of the stop is on the upstream side of the zoom optical system on the optical path, even if zooming is performed, the zoom optical system does not cut off the ambient light by the stop, and a constant brightness (F) at all zoom positions. Number). This makes it possible to realize bright projection even on the telephoto side.

  According to still another aspect of the present invention, the first group has a lens made of abnormally low dispersion glass in the vicinity of the stop. In this case, chromatic aberration can be corrected efficiently. In general, abnormally low dispersion glass is often arranged on the light source side of the stop. In that case, the temperature of the abnormally low dispersion glass rises due to the light beam that is kicked (blocked) by the diaphragm. In particular, the abnormally low dispersion glass has a characteristic that the refractive index largely fluctuates as the temperature rises. By arranging the abnormally low dispersion glass on the screen side of the stop as in the present invention, it becomes possible to minimize the influence of temperature and efficiently correct chromatic aberration.

  According to still another aspect of the present invention, the second group can move back and forth on the optical path. In this case, the first operation state in which the second group is arranged on the optical path and the aspect ratio or aspect ratio is converted and projected, and the second group is not arranged on the optical path and the aspect ratio or aspect ratio is not converted. It is possible to switch to the second operation state in which projection is performed. In addition, by allowing the second group to advance and retreat, it becomes easier to cool the region between the first group and the second group in which the diaphragm is disposed.

  According to still another aspect of the present invention, the projection optical system further includes a cooling device that is disposed around the stop and cools the stop and the vicinity of the stop. In this case, the heat generated by the light shielding by the diaphragm can be positively removed using the cooling device. Furthermore, the Schlieren phenomenon in which a refractive index gradient occurs in the air due to a temperature difference can be prevented, and a good image can be maintained.

  According to still another aspect of the present invention, the stop is disposed between the first group and the second group at a position where the principal ray of each ray from the light modulation element and the peripheral ray are substantially parallel. ing. In this case, highly accurate light shielding is possible at the stop.

  A projector according to the invention includes the above-described projection optical system and a light modulation element. According to this projector, since the influence of heat generated in the projection optical system can be suppressed, optical performance can be maintained, and good image quality can be ensured during projection.

It is a figure explaining the use condition of the projector which concerns on 1st Embodiment. It is a figure which shows schematic structure of the projector of FIG. It is a figure explaining the structure of a projection optical system among the projectors of FIG. (A) shows the configuration of the cross section of the projection optical system, and (B) shows the configuration of the vertical section of the projection optical system. (A) shows the first operation state of the projection optical system, and (B) shows the second operation state of the projection optical system. It is a partially expanded view for demonstrating the periphery of an aperture stop including an aperture stop and a cooling device. (A) is a front view showing a relatively open aperture and its surroundings, and (B) is a front view showing a relatively closed aperture and its surroundings. It is a figure explaining the structure of the cross section of the optical system of Example 1 of 1st Embodiment. It is a figure explaining the structure of the longitudinal cross-section of the optical system of Example 1 of 1st Embodiment. (A) shows the structure of the horizontal cross section of the projection optical system of the projector which concerns on 2nd Embodiment, (B) shows the structure of the vertical cross section of a projection optical system.

  Hereinafter, a projector and a projection optical system according to an embodiment of the invention will be described in detail with reference to the drawings.

[First Embodiment]
As shown in FIG. 1, the projector 2 according to the first embodiment of the present invention forms image light PL according to an image signal, and projects the image light PL toward a projection surface such as a screen SC. When the projection optical system 20 of the projector 2 enlarges and projects an image of the liquid crystal panel 18G (18R, 18B), which is a light modulation element incorporated in the projector 2, onto the screen (projection surface) SC, the liquid crystal panel 18G. The aspect ratio or aspect ratio AR2 of the image projected on the screen SC can be made different from the aspect ratio or aspect ratio AR0 of the image of (18R, 18B). That is, the aspect ratio AR0 of the display area A0 of the liquid crystal panel 18G and the aspect ratio AR2 of the display area A2 of the screen SC can be different, but can also be the same. Specifically, the aspect ratio AR0 of the display area A0 of the liquid crystal panel 18G is, for example, 1.78: 1, and the aspect ratio AR2 of the display area A2 of the screen SC is, for example, 1.78: 1, 1.. 85: 1, 2.35: 1, 2.4: 1, etc.

  As shown in FIG. 2, the projector 2 includes an optical system portion 50 that projects image light, and a circuit device 80 that controls the operation of the optical system portion 50.

  In the optical system portion 50, the light source 10 is an ultra-high pressure mercury lamp, for example, and emits light including R light, G light, and B light. Here, the light source 10 may be a discharge light source other than an ultra-high pressure mercury lamp, or may be a solid light source such as an LED or a laser. The first integrator lens 11 and the second integrator lens 12 have a plurality of lens elements arranged in an array. The first integrator lens 11 splits the light flux from the light source 10 into a plurality of parts. Each lens element of the first integrator lens 11 condenses the light beam from the light source 10 in the vicinity of the lens element of the second integrator lens 12. The lens elements of the second integrator lens 12 cooperate with the superimposing lens 14 to form images of the lens elements of the first integrator lens 11 on the liquid crystal panels 18R, 18G, and 18B. With such a configuration, the light from the light source 10 illuminates the entire display area (display area A0 in FIG. 1) of the liquid crystal panels 18R, 18G, and 18B with substantially uniform brightness.

  The polarization conversion element 13 converts light from the second integrator lens 12 into predetermined linearly polarized light. The superimposing lens 14 superimposes the image of each lens element of the first integrator lens 11 on the display area of the liquid crystal panels 18R, 18G, and 18B via the second integrator lens 12.

  The first dichroic mirror 15 reflects R light incident from the superimposing lens 14 and transmits G light and B light. The R light reflected by the first dichroic mirror 15 passes through the reflection mirror 16 and the field lens 17R and enters the liquid crystal panel 18R that is a light modulation element. The liquid crystal panel 18R forms an R color image by modulating the R light according to the image signal.

  The second dichroic mirror 21 reflects the G light from the first dichroic mirror 15 and transmits the B light. The G light reflected by the second dichroic mirror 21 passes through the field lens 17G and enters the liquid crystal panel 18G that is a light modulation element. The liquid crystal panel 18G modulates the G light according to the image signal to form a G color image. The B light transmitted through the second dichroic mirror 21 passes through the relay lenses 22 and 24, the reflection mirrors 23 and 25, and the field lens 17B and enters the liquid crystal panel 18B that is a light modulation element. The liquid crystal panel 18B forms a B-color image by modulating the B light according to the image signal.

  The cross dichroic prism 19 is a light combining prism, which combines light modulated by the liquid crystal panels 18R, 18G, and 18B into image light and advances it to the projection optical system 20.

  The projection optical system 20 enlarges and projects the image light PL modulated by the liquid crystal panels 18G, 18R, and 18B and synthesized by the cross dichroic prism 19 on the screen SC in FIG. At this time, the projection optical system 20 sets the aspect ratio AR2 of the image projected on the screen SC to be different from the aspect ratio AR0 of the images of the liquid crystal panels 18G, 18R, and 18B. Can be equal.

  The circuit device 80 includes an image processing unit 81 to which an external image signal such as a video signal is input, and display driving for driving the liquid crystal panels 18G, 18R, and 18B provided in the optical system portion 50 based on the output of the image processing unit 81. Unit 82, a lens driving unit 83 that adjusts the state of the projection optical system 20 by operating a drive mechanism (not shown) provided in the projection optical system 20, and operations of these circuit portions 81, 82, 83, etc. And a main control unit 88 for controlling automatically.

  The image processing unit 81 converts the input external image signal into an image signal including a gradation of each color. When the projection optical system 20 is in the first operation state in which the projection optical system 20 converts and projects the aspect ratio or aspect ratio (aspect ratio) of the image, the conversion of the aspect ratio by the projection optical system 20 is reversed. The aspect ratio conversion of the processed image is performed in advance so that the image displayed on the screen SC does not expand or contract vertically or horizontally. Specifically, when the image is expanded in the horizontal direction by the projection optical system 20 so as to be, for example, 1.78: 1 to 2.4: 1, for example, 0.742 = 1.78 in the horizontal direction in advance. The image is compressed by /2.4 times, or the image is expanded by 1.35 = 2.4 / 1.78 times in the vertical direction. On the other hand, when the projection optical system 20 is in the second operation state in which the projection is performed without converting the aspect ratio or aspect ratio of the image, the image processing unit 81 does not perform the aspect ratio conversion of the image as described above. The image processing unit 81 can also perform various image processing such as distortion correction and color correction on the external image signal. Further, in the case where the input external image signal is data that has been compressed or expanded in advance, it is possible to prevent image processing even in the first operation state.

  The display driving unit 82 can operate the liquid crystal panels 18G, 18R, and 18B based on the image signal output from the image processing unit 81, and can display an image corresponding to the image signal or an image that has been subjected to image processing. Corresponding images can be formed on the liquid crystal panels 18G, 18R, 18B.

  The lens driving unit 83 operates under the control of the main control unit 88. For example, the lens driving unit 83 appropriately moves a part of optical elements constituting the projection optical system 20 along the optical axis OA. The projection magnification of the image on the screen SC can be changed. Further, the lens driving unit 83 advances and retracts another part of the optical elements constituting the projection optical system 20 on the optical axis OA, that is, on the optical path, so that the image projected on the screen SC in FIG. The ratio AR2 can be changed. The lens driving unit 83 changes the vertical position of the image projected on the screen SC in FIG. 1 while suppressing distortion by adjusting the tilt of moving the entire projection optical system 20 in the vertical direction perpendicular to the optical axis OA. Can be made. The lens driving unit 83 operates a diaphragm 70 (see FIG. 3), which is a movable diaphragm that expands and contracts in a plane parallel to the XY plane, among the diaphragms constituting the projection optical system 20, and adjusts the light shielding amount. For example, high-contrast image formation is possible.

  Hereinafter, the projection optical system 20 of the embodiment will be described with reference to FIG. The projection optical system 20 includes a main body portion 20a formed by combining a plurality of optical elements such as lenses, and driving mechanisms 61, 62, 63, which adjust the image formation state by moving a part or the whole of the main body portion 20a. 64.

  The main body portion 20a includes a first group 30, a second group 40, a diaphragm 70, and a third group 60 in order from the screen SC side. Here, the diaphragm 70 is disposed between the first group 30 and the second group 40 and is fixed together with the first group 30. The projection optical system 20 includes a cooling device 90 that cools the diaphragm 70.

  The first group 30 includes a first lens unit 31 and a second lens unit 32. For example, the focus state of the main body portion 20a can be adjusted by finely moving at least one lens constituting the first lens unit 31 manually along the optical axis OA. Further, at least one lens constituting the second lens unit 32 can be moved along the optical axis OA by the drive mechanism 61 of FIG. 3 to change the projection magnification by the main body portion 20a. That is, the first group 30 is an enlargement optical system and a zoom optical system.

  The second group 40 is an adjustment optical element having different focal lengths in the horizontal direction (X direction) and the vertical direction (Y direction). As a result, the entire second projection optical system 20 including the first group 30 may be used. The focal length is different between the vertical direction and the horizontal direction. That is, when projected by the main body portion 20a, the vertical magnification and the horizontal magnification are different from each other, and the aspect ratio different from the aspect ratio AR0 of the image displayed on the liquid crystal panel 18G (18R, 18B). The image of AR2 can be projected on the screen SC. The second group 40 includes one or more optical elements for adjustment having a rotationally asymmetric surface with respect to the optical axis OA. Specifically, the second group 40 is a cross section in the vertical direction (Y direction) shown in FIG. , In order from the screen SC side, the first optical element group 41 having positive power and the second optical element group 42 having negative power are configured. The first optical element group 41 and the second optical element group 42 do not have power with respect to the cross section in the horizontal direction (X direction) shown in FIG.

  Thus, the second group 40, which is an anamorphic optical system, is a combination of the first optical element group 41 having a positive refractive power and the second optical element group 42 having a negative refractive power with respect to the longitudinal section. By doing so, the second group can function like an afocal system, and zooming, that is, zooming can be performed easily.

  The first group anamorphic drive mechanism 62, which is the advance / retreat drive mechanism shown in FIG. 3, moves the second group 40 back and forth on the optical path, so that the aspect ratio or aspect ratio of the image projected on the screen SC can be set to a desired timing. Can be switched. Specifically, as shown in FIG. 5A, the image formed on the liquid crystal panel 18G (18R, 18B) is displayed in the vertical direction by setting the second group 40 in the first operation state arranged on the optical path. An image can be projected on the screen SC with an aspect ratio (for example, 2.4: 1) compressed into the screen SC. Alternatively, as shown in FIG. 5B, the second group 40 is moved from the optical path to the second operation state so that the image formed on the liquid crystal panel 18G (18R, 18B) remains as it is. An image can be projected on the screen SC at a ratio (eg, 1.78: 1). The configuration in which an image projected on the screen SC by the second group 40 is compressed in the vertical direction is effective when the screen SC having a fixed horizontal dimension is used. That is, it is possible to change only the aspect ratio of such a screen SC without changing the projection distance by the projection optical system 20. Note that the first optical element group 41 and the second optical element group 42 constituting the second group 40 can be moved in the direction of the optical axis OA by the second anamorphic driving mechanism 63. By adjusting these intervals, the aspect ratio or aspect ratio (aspect ratio) of the image projected on the screen SC can be continuously increased or decreased.

  As shown in FIG. 5B, when the projection optical system 20 is in the second operation state, that is, when the second group 40 is retracted from the optical path, the projection optical system 20 includes the first group 30 and the third group. 60 is configured by only rotationally symmetric optical elements, so that the aspect ratio or aspect ratio of the display area A0 of the liquid crystal panel 18G (18R, 18B) and the width of the display area A2 of the screen SC. The aspect ratio or aspect ratio is the same. Here, the first group 30 has the same functions of a magnifying optical system and a variable magnification optical system as a general projection optical system, and an image of the liquid crystal panel 18G is formed on the screen SC only by the first group 30. Can do. Further, when the second group 40 is retracted, the transmittance is improved and the image can be brightened. Although described in detail later, the third group 60 has a plurality of lenses and functions as a correction optical element that suppresses aberration of the entire optical system.

  As shown in FIG. 3, in the projection optical system 20, the entire system drive mechanism 64 moves the entire body portion 20a in the direction perpendicular to the optical axis OA to adjust the shift amount, thereby projecting onto the screen SC. It is possible to increase or decrease the amount of deviation from the optical axis OA of the image to be performed with little image distortion. That is, the optical axis OA of the main body portion 20a is moved by an appropriate shift amount SF with respect to the central axis AX of the liquid crystal panel 18G while keeping the optical axis OA of the main body portion 20a parallel to the central axis AX of the liquid crystal panel 18G. By doing so, an image can be projected at a position deviated, for example, upward (+ Y direction) from the optical axis OA, and the projection position of the image can be changed with respect to the vertical direction by adjusting the shift amount SF. Note that the shift amount SF, which is a shift amount with respect to the central axis AX of the liquid crystal panel 18G of the optical axis OA of the main body portion 20a, does not necessarily need to be variable, and can be fixed at a non-zero value, for example. The drive mechanism 61, the first anamorphic drive mechanism 62 that is an advance / retreat drive mechanism, the second anamorphic drive mechanism 63, and the entire system drive mechanism 64 include a motor, a mechanical transmission mechanism, a sensor, and the like. It operates according to the drive signal from the lens drive unit 83. These drive mechanisms 61, 62, 63, 64 not only operate independently by the drive signal from the lens drive unit 83 but also operate in combination.

  Referring back to FIGS. 4A and 4B, the third group 60 includes one or more rotationally symmetric optical element rotationally symmetric lenses having power in the horizontal and vertical directions. Since the third group 60 has a positive power, it is possible to suppress the spread of light emitted from the light modulation element. Therefore, the angle of light incident on the second group 40 can be suppressed, and aberrations that occur in the second group 40 can be suppressed. As a result, the third group 60 has a role of suppressing the aberration of the projection optical system 20 as a whole, has a plurality of lenses as correction optical elements, and has a positive power lens among these lenses. If so, an aspherical surface is included. In addition, as a result of suppressing the spread of the light emitted from the light modulation element in the third group 60, the light beams of the respective image heights from the third group 60 are chief rays as shown in the light beam LL1 schematically shown as an example in FIG. Is almost parallel.

  The diaphragm 70 is disposed between the first group 30 and the second group 40, and is disposed, for example, in the first group 30 close to the second lens unit 32. The diaphragm 70 partially blocks the light beam, that is, blocks a part of the light beam that passes through the second group 40 and travels toward the first group 30, so that the light beam emitted from the liquid crystal panel 18 </ b> G (18 </ b> R, 18 </ b> B). The emission angle and direction of the peripheral rays of light can be adjusted. That is, the diaphragm 70 adjusts the F number at each position on the screen of the liquid crystal panel 18G (18R, 18B). The diaphragm 70 is a movable diaphragm, and expands and contracts by a driving mechanism 61 that operates according to a driving signal from the lens driving unit 83. The diaphragm 70 is a dimming member that has an annular shape with the optical axis OA as the central axis, and is a movable diaphragm that expands and contracts in a plane parallel to the XY plane, so that the diaphragm amount, that is, the light shielding amount can be adjusted. . Specifically, dimming is performed by increasing / decreasing the cut amount of a component passing through a peripheral position away from the optical axis OA among the light beams traveling from the second group 40 to the first group 30, for example, by setting the aperture 70. In the extended state (closed state), the peripheral component away from the optical axis OA that tends to reduce the contrast is shielded at the aperture 70, and the F number is increased (darkened) to increase the contrast. An image can be formed. It is also possible to form a bright image by reducing the amount of light shielding.

  Here, in a general conventional projection optical system, a diaphragm is often arranged in a sealed space in a lens frame in which the magnifying optical system is assembled, and the diaphragm and its periphery are difficult to cool. Therefore, such a conventional diaphragm is assumed to be a variable diaphragm for high contrast, and in order to enhance the effect of contrast, the position where the light beam at the image height position passes over the entire area (pupil position) or the vicinity thereof If it is disposed at the position, the temperature tends to rise particularly, and it is considered that the optical performance of the lens around the aperture is greatly affected.

  On the other hand, in the present embodiment, the arrangement of the diaphragm 70 that is a variable diaphragm is set between the first group 30 that is an expansion optical system and the second group 40 that includes an anamorphic optical system in order to achieve high contrast. . In this case, the diaphragm 70 is disposed at a position where it can be easily cooled even if the temperature rises due to light shielding. For example, in the present embodiment, as described above, it is possible to switch between the first operation state and the second operation state, that is, the second group 40 can be advanced and retracted with respect to the first group 30. For this reason, a gap is originally easily formed between the first group 30 and the second group 40, and the diaphragm 70 at this position is relatively easy to dissipate heat. Furthermore, here, by providing the cooling device 90 in the vicinity of the diaphragm 70, the diaphragm 70 and its periphery can be efficiently cooled, and the temperature of the optical members around the diaphragm 70 rises due to heat. This can be suppressed.

  For example, the diaphragm 70 can be highly effective due to the contrast by being disposed at a position where the light beam at the image height position passes over the entire region (pupil position) or a position in the vicinity thereof. A lot of heat is generated along with the light shielding, the temperature rises, and it is transmitted through the lens frame and the air, so that the temperature of the lenses constituting the first group 30 and the like arranged in the vicinity of the stop 70 can be raised. Increases the nature. If the temperature of these lenses is greatly increased, the radius of curvature of the lens, the lens thickness (interval), and the refractive index of the lens will change, greatly affecting the optical performance of the projection optical system 20. . In addition, these lenses are often arranged in a sealed space in the lens frame in order to improve the light shielding property, which causes a further increase in temperature. In addition, since this temperature increase is a local phenomenon that occurs in the vicinity of the diaphragm 70, a non-uniform temperature distribution occurs over the entire area of the projection optical system 20, and it is difficult to predict the temperature increase situation. When those temperature distribution widths become extremely large, a refractive index gradient also occurs in the air, and a schlieren phenomenon occurs. That is, fluctuations occur in the air, and the image light is refracted to adversely affect the image. In addition, in order to correct chromatic aberration, a lens made of an extraordinarily low dispersion glass having a negative refractive index temperature coefficient is often arranged on the lens near the iris 70 located at or near the pupil position. It becomes easy to move in the same direction as the back focus movement amount due to the temperature rise of the frame, and it is difficult to cancel the influence due to the movement amount due to the temperature rise of the lens frame by adjusting the back focus movement amount due to the glass temperature rise. From the above background, it is desirable to eliminate as much as possible the influence of the temperature rise due to the diaphragm 70. In the present embodiment, as described above, the diaphragm 70 is disposed at a position where heat is relatively easy to dissipate, and further, by providing the cooling device 90, the temperature of the optical members around the diaphragm 70 is suppressed from increasing, The optical performance of the projection optical system 20 can be maintained while avoiding the lens performance degradation as described above. Further, since a local temperature gradient can be prevented from occurring, the Schlieren phenomenon can be prevented.

  In addition, as described above, the third group 60 composed of the correction optical elements can be arranged in the vicinity of the position where the diaphragm 70 is incident on the first group 30 that is the magnifying optical system through the second group 40 that is the anamorphic optical system. This is because the angle is corrected in the direction in which the light emitted from the liquid crystal panel 18G (18R, 18B) side is narrowed in the third group 60 by being provided.

  6 is a partially enlarged view of the diaphragm 70 and its periphery, and FIGS. 7A and 7B are front views as seen from the image plane side, that is, the liquid crystal panel 18G side. Further, as shown in FIG. 6, here, a cooling device 90 is provided in the vicinity of the diaphragm 70. The cooling device 90 includes a blower 91 that blows air toward the throttle 70 and cooling fins 92 that contact the throttle 70 and radiate heat.

  Here, as shown in FIG. 6, the diaphragm 70 includes a lens group 32 x that is a part of the second lens unit 32 that is disposed closest to the second group 40 (−Z side) of the first group 30, and The second group 40 is disposed between the lens group 41x of the first optical element group 41 disposed on the most first group 30 side (+ Z side). Further, as shown in FIGS. 7A and 7B, the diaphragm 70 is configured by combining a plurality of diaphragm blades 70a (eight in the drawing), and has a circular shape that is rotationally symmetric about the optical axis OA. It has an outer shape. As shown in the figure, the diaphragm 70 functions as a movable diaphragm that changes the size of the opening OP by opening and closing the plurality of diaphragm blades 70a. As described above, the first group 30 is a zoom optical system, and includes a circular lens group rotationally symmetric about the optical axis OA (see the lens group 32x shown in FIG. 7A). Therefore, the first lens frame portion LB1 that supports the optical system of the first group 30 such as the lens group 32x has a cylindrical shape with the optical axis OA as the central axis. On the other hand, the second group 40 is an anamorphic optical system, and is composed of a rectangular cylindrical lens (see the lens group 41x shown in FIG. 7A). Accordingly, the second lens frame portion LB2 that supports the optical system of the second group 40, such as the lens group 41x, can be simplified if it has a rectangular support portion. From the above, the second lens frame portion LB2 and the first lens frame portion LB1 do not have the same shape but have different structures. Further, the second group 40 can advance and retreat with respect to the first group 30. For this reason, between the 1st group 30 and the 2nd group 40 is a location which must carry out mechanical separation. From the above, between the first group 30 and the second group 40, that is, in the vicinity of the diaphragm 70, it is relatively easy to exhaust heat and cool. For example, the lens group 32x which is a part of the first group 30 is replaced with an abnormally low dispersion glass. Even if the lens is made of a lens, heat generated by the diaphragm 70 on the upstream side of the optical path of the first group 30 can be released, and the influence of temperature can be reduced. Note that the configuration of the diaphragm 70 shown in FIGS. 7A and 7B is an example, and various other forms of variable diaphragms can be applied.

  Hereinafter, the details of the configuration of the cooling device 90 will be described, and an example of a cooling method of the diaphragm 70 and its surrounding optical members by the cooling device 90 will be described.

  The blower 91 includes a pair of blower fans 91a and 91b that blow air toward the aperture 70, and a fan drive device 91c that drives the blower fans 91a and 91b. The pair of blower fans 91a and 91b are arranged at positions outside the optical path and not affecting the advance / retreat operation of the second group 40, and are provided symmetrically in the vertical direction or the horizontal direction with respect to the optical axis OA, for example. It has been. The blower fans 91a and 91b are appropriately adjusted in the amount of blown air by the fan driving device 91c and blown toward the diaphragm 70, and cool the diaphragm 70 and its nearby members appropriately. The fan driving device 91c includes a motor, a mechanical transmission mechanism, a sensor, and the like, and operates according to a driving signal from the lens driving unit 83 in FIG. Here, the blower 91 is a pair of blower fans 91a and 91b. However, the blower 91 may be composed of a single fan or may be composed of two or more fans. Further, it is not always necessary to bring the fans close to each other, and for example, a duct or the like can be provided to blow air remotely.

  The cooling fin 92 is a ring-shaped member that surrounds and fixes the diaphragm 70 from the periphery, and is made of a material having a relatively high thermal conductivity such as aluminum, and is in contact with the diaphragm 70 on the outer edge side. The heat generated by shading is conducted and released. Note that the cooling fins 92 are fixed by being attached to the first lens frame part LB1 by a nail NL or the like. Thereby, the relative position of the diaphragm 70 with respect to the first group 30 in the optical axis direction is also fixedly determined.

  As described above, in the present embodiment, not only the diaphragm 70 is originally disposed at a position where it is easily cooled, but the diaphragm 70 is actively cooled by providing the cooling device 90, so that the diaphragm 70 and its It is possible to more efficiently suppress the generation of heat in the vicinity.

  The stop 70 is located on the upstream side of the first group 30 that is the optical system zoom optical system. In this case, the light beam in a state where the peripheral component passing through the position away from the optical axis OA by the stop 70 has already been cut is directed to the first group 30. For this reason, in the zooming operation in the first group 30, there is no situation in which the light shielding at the aperture 70 affects the determination of the brightness of the zoom optical system. Accordingly, a constant brightness is substantially maintained at all zoom positions in the first group 30 that is a zoom optical system, and for example, bright projection can be realized even on the telephoto side.

  Further, in the case of the projection optical system 20 of the above-described embodiment, the compression conversion can be performed by making one or both surfaces of the optical element groups 41 and 42 constituting the second group 40 as the adjustment optical element a cylindrical lens surface. Become. Since these cylindrical lenses have a shape having a curvature only in one direction, processing is easy, high accuracy can be expected, and cost can be reduced. Moreover, the eccentric sensitivity on the plane cross-section side is low, the assemblability is improved, and as a result, high performance can be expected. That is, by configuring the second group 40 with a cylindrical lens, the cost can be reduced while ensuring the accuracy of the projection optical system 20.

  Note that one or both surfaces of the optical element groups 41 and 42 constituting the second group 40 are not limited to cylindrical lens surfaces, but may be anamorphic lenses (for example, toric or toroidal lenses).

ここで、ｙは光軸ＯＡからの像の高さ（像高）、ｃは基準とする球面の曲率、ｋは円錐定数、Ａ２、Ａ４、Ａ６、Ａ８、Ａ１０、・・・のそれぞれは所定の補正項とする。 In the above, one side or both sides of the cylindrical or anamorphic lens type optical element groups 41 and 42 constituting the second group 40 are aspherical with respect to the horizontal X cross section or the vertical Y cross section. It can have a shape represented by a polynomial h.

Here, y is the height of the image from the optical axis OA (image height), c is the curvature of the reference spherical surface, k is the conic constant, and A2, A4, A6, A8, A10,. This is the correction term.

  Furthermore, one or both surfaces of the optical element groups 41 and 42 constituting the second group 40 can be free-form surfaces. By using an anamorphic lens, the curvature can be controlled in both cross sections in the Y direction and the X direction, so that astigmatism can be reduced and high performance can be achieved. In addition, by using an aspherical surface, various aberrations can be reduced and high performance can be achieved. Further, by forming a free-form surface, an image forming state in an intermediate oblique direction other than the vertical and horizontal directions of the liquid crystal panel 18G (18R, 18B) on the screen SC or the image circle surface on the liquid crystal panel 18G (18R, 18B). Optimization becomes easy, and high performance is possible.

The second group 40 is not limited to the two optical element groups 41 and 42 but can be constituted by three or more optical element groups. At this time, it is desirable that no chromatic aberration is generated by the second group 40. For this reason, the following relationship Σ (φi × νi) ≈0
here,
φi: Refractive index of each lens composing the second group 40 νi: It is desirable that the Abbe number of each lens composing the second group 40 is established.

  As described above, according to the projection optical system 20 of the present embodiment, the second group 40 is an anamorphic optical system having different powers in the adjustment direction and the other direction of the liquid crystal panel 18G that is a light modulation element. The aspect ratio, which is the ratio between the height and the height, can be converted. A stop 70 is disposed between the first group 30 that is an expansion optical system and the second group 40 that is an anamorphic optical system. Thereby, the diaphragm 70 can be cooled relatively easily, and the heat generated by shielding the light beam can be suppressed from being transmitted to the optical member disposed in the vicinity of the diaphragm 70 and having an influence.

[Example 1]
FIGS. 8 and 9 are diagrams for explaining a specific example 1 of the projection optical system 20 of the first embodiment, and show the projection optical system 20 in the first operation state. FIG. 8 shows a state of a transverse section, and FIG. 9 shows a state of a longitudinal section.

に適宜数値を入れることで、形状が特定される。図示のように、第３群６０において、収差の補正がなされる結果、第３群６０は、各光線の主光線と周辺光線とを略平行な状態にして射出させるものとなっており、この状態は、絞り７０付近においても保たれている。 The projection optical system 20 includes lenses L1 to L24 and a diaphragm 70. Among the lenses L1 to L24, the first group 30 is configured by the lenses L1 to L16, the second group 40 is configured by the lenses L17 to L21, and the third group 60 is configured by the lenses L22 to L24. The diaphragm 70 is disposed between the lens L16 of the first group 30 and the lens L17 of the second group 40. The lenses L1 to L16 included in the first group 30 are spherical lenses that are rotationally symmetric about the optical axis OA. In the first group 30, the lenses L <b> 1 to L <b> 7 constitute a first lens unit 31, and the lenses L <b> 8 to L <b> 16 constitute a second lens unit 32. Of the second group 40, the cemented lenses L17 and L18 are lenses having positive power in the vertical Y direction, and are cylindrical lenses having no power in the horizontal X direction. That is, the cemented lenses L17 and L18 constitute the first optical element group 41. In addition, the single lenses L19 to L21 are lenses having negative power in the vertical Y direction as a whole, and are all cylindrical lenses having no power in the horizontal X direction. In other words, the lenses L19 to L21 constitute a second optical element group 42. The lenses L22 and L23 included in the third group 60 are negative meniscus lenses, and the lens L24 is a positive meniscus lens. The lenses L1 and L7 in the first group 30, the lens L21 in the second group, and the lens L23 in the third group 60 are aspherical lenses. In particular, the lens L21 is an anamorphic aspheric lens. Specifically, the shape represented by the above-described polynomial h is similarly applied to the aspherical expression. That is,

The shape is specified by appropriately entering a numerical value in. As shown in the figure, as a result of correcting the aberration in the third group 60, the third group 60 emits the principal ray of each ray and the peripheral ray in a substantially parallel state. The state is also maintained near the aperture 70.

  Further, as shown in the figure, the diaphragm 70 is a movable diaphragm at a position where light beams at all image height positions pass through the entire area of the diaphragm 70, thereby uniformly reducing the light amount of the entire screen. Is possible. That is, the ambient light of one light beam can be cut, so that the optical performance can be improved and unnecessary light from the panel can be cut, leading to an improvement in contrast. In addition to the diaphragm 70, there are diaphragms DP1, DP2, etc., for example. These are fixed diaphragms that do not open and close, and are appropriately provided to suppress the generation of ghost light, flare, and the like.

また、アナモフィック非球面レンズであるレンズＬ２１の非球面データは、以下の表２に示す通りである。

Tables 1 and 2 below show lens data and the like of Example 1. Table 1 relates to the projection optical system 20 in the first operation state. In the upper column of Table 1, “surface number” is a number assigned to the surface or aperture of each lens in order from the image surface side. “R1” and “R2” indicate Y and X radii of curvature, and “D” indicates the lens thickness or air space between the next surface. Furthermore, “Nd” indicates the refractive index of the lens material at the d-line, “νd” indicates the Abbe number at the d-line of the lens material, and “Q1” and “Q2” indicate the Y and X effective diameters. Indicates. In the lower column of Table 1, among the lenses constituting the projection optical system 20 of Example 1, the aspherical surfaces of the lenses L1, L7, and L23 that are aspherical surfaces represented by the above-mentioned aspherical expression or polynomial are shown. The shape is shown.

The aspheric data of the lens L21, which is an anamorphic aspheric lens, is as shown in Table 2 below.

[Second Embodiment]
Hereinafter, a projection optical system and the like according to the second embodiment will be described. Note that this embodiment is a modification of the projection optical system and the like of the first embodiment, and parts or matters that are not particularly described are the same as those of the first embodiment.

  10A and 10B are diagrams illustrating a projection optical system 120 that is a modification of the projection optical system 20 shown in FIGS. 4A and 4B. The second group 140 has different focal lengths in the vertical direction (Y direction) and the horizontal direction (X direction). As a result, even in the entire projection optical system 120 including the first group 30, the vertical direction And have different focal lengths in the horizontal direction. In this case, the second group 140 includes a first optical element group 141 having a negative power and a second optical element group having a positive power in order from the screen SC side with respect to the cross section in the horizontal direction (X direction). 142. Note that the first optical element group 141 and the second optical element group 142 do not have power with respect to the cross section in the vertical direction (Y direction) shown in FIG. As shown in FIGS. 10A and 10B, the second group 40 is disposed on the optical path, and the image formed on the liquid crystal panel 18G (18R, 18B) is expanded in the horizontal direction. For example, an image can be projected on the screen SC in 2.4: 1). Although illustration is omitted, when the second group 140 is retracted from the optical path, the screen SC has an aspect ratio (for example, 1.78: 1) as it is formed on the liquid crystal panel 18G (18R, 18B). Images can be projected on top. That is, the horizontal direction is an adjustment direction for performing conversion adjustment by expansion, and the vertical direction is a non-adjustment direction. Further, the first optical element group 141 and the second optical element group 142 constituting the second group 140 are moved in the direction of the optical axis OA by the second anamorphic driving mechanism 63 in FIG. Thus, the aspect ratio (aspect ratio) or aspect ratio of the image projected on the screen SC can be continuously increased or decreased. The configuration in which the image projected on the screen SC by the second group 40 is expanded in the horizontal direction is effective when the screen SC having a fixed vertical dimension is used. That is, it is possible to change only the aspect ratio of such a screen SC without changing the projection distance by the projection optical system 120.

  As shown in FIGS. 10A and 10B, the diaphragm 170 is disposed between the first group 30 that is an expansion optical system and the second group 140 that is an anamorphic optical system. As a result, the diaphragm 170 can be cooled relatively easily, and the heat generated by blocking the light beam can be prevented from being transmitted to the optical member disposed in the vicinity of the diaphragm 170 and influenced.

  The present invention is not limited to the above embodiment, and can be implemented in various modes without departing from the scope of the invention.

  For example, although the second group 40 and 140 can be advanced and retracted, the image projection may be performed only in the first operation state in which the second group 40 and 140 are always arranged on the optical path without being able to advance and retract. The first lens frame portion LB1 that supports the first group 30 and the second lens frame portion LB2 that supports the second group 40 may be integrated.

  For example, in the above embodiment, the image displayed on the liquid crystal panel 18G or the like is compressed (reduced) in the vertical direction or expanded in the horizontal direction by the second group 40 or the like of the projection optical system 20 or the like, and is relative to the screen SC. Although an image converted to have a horizontally long aspect ratio is projected, it is also possible to project an image that has been converted to have a relatively vertically long aspect ratio by changing the lens configuration of the second group 40 or the like. it can.

  In the above description, conversion adjustment by compression is performed only in the vertical direction, that is, only the vertical direction is the adjustment direction, or conversion adjustment by expansion is performed only in the horizontal direction, that is, only the horizontal direction is the adjustment direction. Further, it is possible to perform an aspect in which both the compression in the vertical direction and the expansion in the horizontal direction are performed, and both the vertical direction and the horizontal direction are adjusted directions.

  The liquid crystal panels 18G, 18R, and 18B are not limited to the transmission type, but may be a reflection type. Here, “transmission type” means that the liquid crystal panel is a type that transmits the modulated light, and “reflection type” means that the liquid crystal panel is a type that reflects the modulated light. ing.

  As the projector, there are a front projection type projector that projects an image from the direction of observing the projection plane and a rear projection type projector that projects an image from the side opposite to the direction of observing the projection plane. Any of the projector configurations shown in FIG.

  Instead of the liquid crystal panels 18G, 18R, 18B, a digital micromirror device having a micromirror as a pixel can be used as the light modulation element.

  2 ... projector, 10 ... light source, 15, 21 ... dichroic mirror, 17B, 17G, 17R ... field lens, 18B, 18G, 18G ... liquid crystal panel, 19 ... cross dichroic prism, 20, 120 ... projection optical system, 20a ... main body Part 30 ... first group 31 ... first lens part (first lens group) 32 ... second lens part 40,140 ... second group 60 ... third group 41,42,141,142 ... Optical element group 50 ... Optical system part 61 ... Zoom drive mechanism 62 ... First anamorphic drive mechanism 63 ... Second anamorphic drive mechanism 64 ... Whole system drive mechanism 70, 170 ... Aperture, 80 ... Circuit device, 81: Image processing unit, 83: Lens drive unit, 88 ... Main control unit, 90 ... Cooling device, AX ... Central axis, L1-L24 ... Lens, OA ... optical axis, PL ... the image light, SC ... screen

Claims (8)

When the image of the light modulation element is enlarged and projected on the projection surface, the aspect ratio of the image of the light modulation element is different from the aspect ratio of the image projected on the projection surface. An optical system,
In order from the projection surface side, the first lens unit, which is an enlargement optical system, has a surface that is rotationally asymmetric with respect to the optical axis, and has different powers in the adjustment direction for performing conversion adjustment by compression or expansion and in other directions. A second group that performs the conversion adjustment with at least one of the vertical direction and the horizontal direction of the light modulation element as the adjustment direction, and an adjustment optical element that includes at least one optical element. A third group of correction optical elements having a rotationally symmetric surface with respect to the axis,
A projection optical system in which a diaphragm for partially blocking light rays is disposed between the first group and the second group.   The projection optical system according to claim 1, wherein the diaphragm is a movable diaphragm capable of adjusting a light shielding amount.   The projection optical system according to claim 1, wherein the first group is a zoom optical system.   The projection optical system according to any one of claims 1 to 3, wherein the first group includes a lens made of an abnormally low dispersion glass in the vicinity of the stop.   5. The projection optical system according to claim 1, wherein the second group is capable of moving back and forth on an optical path.   The projection optical system according to any one of claims 1 to 5, further comprising a cooling device that is disposed around the diaphragm and that cools the diaphragm and a vicinity of the diaphragm.   The stop is disposed between the first group and the second group at a position where the principal ray and the peripheral ray of each ray from the light modulation element are substantially parallel to each other. The projection optical system according to any one of 6 to 6. A projection optical system according to any one of claims 1 to 7;
Comprising the light modulation element,
projector.

Images