JP6642672B2 - Method of manufacturing projection optical system and method of manufacturing image display device - Google Patents

Description

  The present invention relates to a method for manufacturing a projection optical system and a method for manufacturing an image display device.

  The general configuration and function of a projection type image display device using a reflection type light valve will be described with reference to FIG.

  FIG. 1 is an explanatory diagram showing an optical arrangement of a general “projector device” as a projection type image display device.

  In the drawing, reference numeral LB denotes a light valve, reference numeral LS denotes a lamp light source, reference numeral IR denotes an integrator rod, reference numeral LN denotes an illumination lens, reference numeral M denotes a mirror, reference numeral CM denotes a curved mirror, and reference numeral POS denotes a projection optical system. I have.

The light valve LB is an image display element and is of a reflection type.
The lamp light source LS has a lamp LP and a reflector RF, and emits illumination light for illuminating the light valve LB.

  The integrator rod IR, the illumination lens LN, the mirror M, and the curved mirror CM constitute an illumination optical system that guides illumination light emitted from the lamp light source LS to the light valve LB.

  The integrator rod IR is a light pipe in which four mirrors are combined in a tunnel shape, and guides the light incident from the entrance to the exit while reflecting the light on the mirror surface.

  The projection optical system POS projects the reflected light from the light valve LB toward a projection surface such as a screen, and enlarges and forms an “image displayed on the light valve LB” on the projection surface.

  The light valve LB is a “DMD (digital micromirror device)” in this example, and is configured by arranging minute mirrors in an array. The individual micromirrors can change their normal directions independently of each other, for example, within a range of “± 12 degrees”.

  The light emitted from the lamp LP is reflected by the reflector RF and condensed at the entrance of the integrator rod IR. The light incident from the entrance is guided while being repeatedly reflected in the integrator rod IR, and is emitted from the exit as light having uniform illuminance “even in illuminance unevenness”.

  Light emitted from the integrator rod IR illuminates the light valve LB via an illumination optical system including an illumination lens LN, a mirror M, and a curved mirror CM.

  The illumination lens LN, the mirror M, and the curved mirror CM of the illumination optical system use the light emitted from the exit of the integrator rod IR as a “surface light source having uniform illuminance with uniform light intensity” and an image of this surface light source. It is formed on the light valve LB. That is, the light valve LB is irradiated with illumination light having uniform illuminance.

  For example, the tilt angle of the micro mirror in the light valve LB is determined such that when the angle is −12 degrees, the reflected light from the micro mirror is incident on the projection optical system POS, and when the angle is +12 degrees, the light is not incident on the projection optical system POS. The positional relationship between the light valve LB and the projection optical system POS is determined, and the “incident direction of the light from the curved mirror CM to the light valve LB” is set.

  The image can be displayed on the light valve LB by adjusting the inclination of each micromirror according to the pixel of the image to be projected and formed on the projection surface. The image displayed in this way is called a “display image”.

  By displaying an image on the light valve LB and irradiating the light valve LB with the illumination light, the reflected light of each micromirror incident on the projection optical system POS is converted into an image forming light beam by the projection optical system POS to be projected. The image is projected and formed as an enlarged image of the image on the surface. The image formed on the projection surface in this way is called a “projection image”.

  Since the light valve LB is illuminated with “light having a uniform illuminance distribution”, the projection image on the projection surface, which is an enlarged image of the displayed image, also has a uniform illuminance distribution. In this way, a "digital image" can be displayed on the projection surface.

  The above is the description of image display by a general projector device.

  As described above, the function of the projection optical system POS is to “form a projection image, which is a real image of the display image displayed on the light valve LB, on a projection surface such as a screen”. The size of the projected image to be displayed and the distance from the projector device to the projection target surface vary depending on the specific usage of the projector device.

In order to form a projection image on a projection surface, “focusing” is required.
In the “normal projector device” shown in FIG. 2A, the projection optical system POS1 is “coaxially rotationally symmetric”, and the focus of the projection image on the screen SC as the projection surface is adjusted by the entire projection optical system POS1. In general, there is an "overall feeding system" for adjusting the focus by moving the lens, and a focusing system for moving a focus group in which one or more lenses in a lens system are set. In each of the drawings following FIG. 2, the optical axis of the lens system portion of the projection optical system that is rotationally symmetric with respect to the coaxial axis is represented by a symbol “AX”.

  FIG. 2B shows a “refractive optical system POSL1 composed of a plurality of lenses and a mirror optical system POSM1 composed of a non-coaxial reflective surface that does not share an optical axis with the refractive optical system POSL1 (see FIG. 2B). In the example, a projector device using a projection optical system constituted by a single concave mirror is known.) And is becoming widespread.

  As such a projector device, a projector device capable of projecting at a closer distance (ultra-close distance) than ever before has been proposed and being implemented.

When “projecting an image at a close distance or a very close distance” onto the screen SC, it is usually necessary to set the projection position of the projected image to “above the projector device” so that the projected image is easy to see.
For this reason, as shown in FIG. 2, the center of the image display element LB (here, DMD) is generally shifted from the optical axis AX of the projection optical system and arranged eccentrically.
The image quality is maintained by using a wide-angle lens for the projection optical system in order to “widen the performance guarantee range of the projection optical system”.
However, there is a limit to widening the angle of the projection optical system by a coaxial rotationally symmetric lens system. To project a projection image from a “super close position closer to the screen SC”, “make an optical path” by a mirror optical system. There is a need.

  There is also a "diagonal projection" method, in which the optical path of the projection optical system by the lens system is folded back by a plane mirror, the optical axis of the projection optical system is inclined at an angle to the screen, and projection is performed at a short distance. Is possible, but there is a problem of "trapezoidal distortion" in which the display screen is distorted in a trapezoidal shape.

In the projection method shown in FIG. 2B, the trapezoidal distortion of the projection image can be effectively corrected by setting the mirror shape of the concave mirror constituting the mirror optical system POSM1 to a “free-form surface”.
Non-Patent Document 1 describes such “correction of trapezoidal distortion by a mirror having a free-form surface” in detail.

  As shown in FIG. 2B, in a projector apparatus that corrects trapezoidal distortion using a refractive optical system POSL1 and a mirror optical system POSM1 and using a “free-form mirror” for the mirror optical system POSM1, As a focusing method suitable for performing “focusing”, a “floating focus method” can be considered.

  In this case, the “floating focus method” is to fix the “one or more lenses” closest to the light valve LB (DMD) and move the other two or more lenses, lens groups, and mirrors in the optical axis direction to focus. This is a focusing method that matches

  In particular, focusing at a close distance or at a very close distance is called the floating focus method because it moves multiple lens groups like a floating tree to adjust the focus, and in particular, it is an `` interchangeable lens for single-lens reflex camera '' Widely used in

  In the case of the whole feeding method and the focusing by “single lens or lens group”, correction of trapezoidal distortion when projecting a projected image from a close distance to the screen SC tends to be insufficient, and correction of field curvature is performed. Is also insufficient, causing a problem that the center of the display screen and the periphery thereof are out of focus.

  In the floating focus method, distortion of an image generated when a projected image is projected from a close distance to the screen SC is mainly corrected by a “non-coaxial curved mirror”. Correction of curvature of field can be performed well.

This will be described more specifically.
FIG. 3A shows a projector device of “oblique projection”. For the sake of simplicity of illustration, the plane mirror that folds the optical path is not shown.

  A projection image is projected and displayed on the screen SC by the projection optical system POS0.

  The light valve LB is “DMD” and its image display surface is “horizontally long rectangular shape” in which the vertical direction (Y direction) of the screen SC is short as shown in the upper diagram of FIG. The projected image projected above has a “trapezoidal shape” as shown in the lower diagram of FIG.

  FIG. 4A shows a projection type projector device using a projection optical system including a refractive optical system POSL1 and a mirror optical system POSM1. The mirror optical system POSM1 is a concave mirror.

  In this projector device, the image display surface of the light valve LB (DMD) has a rectangular shape as shown in the upper diagram of FIG. 4B, and the refraction optical system POSL1 converts the real image of this image display surface into the intermediate image Im0. An image is formed between the refraction optical system POSL1 and the mirror optical system POSM1, and the mirror optical system POSM1 forms an image on the screen SC using the intermediate image Im0 as the object image.

  The intermediate image Im0 formed by the refractive optical system POSL1 has a “trapezoidal shape with a narrow upper portion” as shown in the middle part of FIG. Then, the distortion is corrected by the mirror optical system POSM1, and a “rectangularly corrected projected image” is formed on the screen SC as shown in the lower diagram of FIG. 4B.

  In order to display the “smaller projected image” on the screen SC with the projector device of FIG. 4, as shown in FIG. 5A, the screen SC is moved in the Z direction (from the position of FIG. 4A). Let us consider a case where the lens is moved to the right side and the focusing is performed by “entire extension in the Z direction” of the refracting optical system POSL1 which is a coaxial system.

  In this case, since the distortion of the intermediate image Im0 hardly changes before and after the entire feeding of the refractive optical system POSL1, the shape of the intermediate image Im0 is changed as shown in the middle part of FIG. This is the same as in the case of the lower diagram, and a “trapezoidal distortion in which the upper side is shortened” occurs in the projected image on the screen SC as shown in the lower diagram of FIG. 5B.

This phenomenon will be described in more detail with reference to FIG.
FIG. 6A shows a state in which FIG. 4A is viewed from above, that is, an XZ cross section of FIG. 4A.

  As shown in FIG. 6A, in the projection optical system using the concave mirror POSM1, the angles of light directed upward and downward in the Y direction of the display screen on the screen SC are different in the XZ section.

  FIG. 6C shows a shape of a projected image when proper projection is performed as shown in FIG. 6A, and has a rectangular shape.

  When the screen SC is moved as shown in FIG. 5A, as shown in FIG. 6B showing the XZ cross section in this state, the position in the X direction reaching the screen SC differs between the upper and lower portions of the display screen. As shown in FIG. 6D, “trapezoidal distortion with a short upper side” occurs.

  When the distance between the light valve and the refractive optical system (the distance in the normal direction of the light valve) is appropriate, the "floating focus method" is very effective for correcting trapezoidal distortion and correcting the field curvature described above. is there.

  In focusing by the floating focus method, since the curvature of field strongly acts, for example, as shown in FIG. 7, the screen SC is moved to the screen position SC (1) (the state shown in FIG. 4A). To the screen position SC (2) (the state shown in FIG. 5A), as in the case where the focus adjustment amount is significantly different between the upper and lower portions of the display screen, as when approaching the curved mirror POSM1. It is valid.

  However, when the focus adjustment amount to be adjusted is the same over the entire display screen, focusing by the floating focus method does not function effectively. In such a case, the focus adjustment by the whole extension method or the front group extension method is performed. Is valid.

  Various methods for focusing a projector device have been widely known (for example, Patent Documents 1 to 3).

  Focusing by the floating focus method mainly has the function of correcting "center and peripheral defocus" on the display screen, but "variation in the distance between the refractive optical system and the light valve" and "variation in the focal length of the refractive optical system" When the focus of the whole projected image is "blurred" due to "", it is not suitable for correcting this.

The present invention has been made in view of the above-mentioned circumstances, and has a refractive optical system and a mirror optical system, and has a function of correcting “a different focus adjustment amount between upper and lower parts” of a display screen, and “ It is an object of the present invention to provide a method of manufacturing a projection optical system having a function of correcting "out of focus".

The method for manufacturing a projection optical system according to the present invention includes, in order from the object side, a refractive optical system including a plurality of lens groups, and a mirror optical system having a curved mirror, and the most object-side refractive optical system on the object side. While maintaining the distance between the lens surface on the conjugate plane side and the conjugate plane on the object side, some lens groups in the refractive optical system are moved in the normal direction of the conjugate plane on the object side to display the display screen. A first focus adjustment unit that corrects a different focus adjustment amount between an upper side and a lower side, and maintains a predetermined distance between a lens surface closest to the object-side conjugate surface and the object-side conjugate surface of the refractive optical system. A projection optical system for enlarging and projecting an image of an object, wherein the lens of the refractive optical system is moved by the second focus adjustment unit. And the conjugate of the refractive optical system closest to the object side After performing focus adjustment to adjust the focus of the entire display screen by changing the distance between the lens surface on the side and the conjugate surface on the object side, the lens surface of the refractive optical system closest to the conjugate surface on the object side The predetermined distance from the conjugate plane on the object side is fixed.

  As described above, the projection optical system manufactured by the manufacturing method of the present invention includes two separate focus adjustment units called first and second focus adjustment units, and the first focus adjustment unit includes: When the real image of the image display element is projected onto the projection surface to perform focusing, it is possible to perform focusing by a floating focus method.

Further, the distance between the lens surface of the refractive optical system closest to the conjugate surface on the object side and the conjugate surface of the object side is changed by the second focus adjustment unit, and “variation in the distance between the refractive optical system and the light valve” is performed. And "focus blur of the entire projected image" due to "variation in the focal length of the refractive optical system" can be effectively corrected, and the focus of the entire projected image can be adjusted.

  The focus adjustment of the projection optical system is performed by the second focus adjustment unit, and the second focus adjustment unit is fixed after the focus adjustment. Therefore, the second focus adjustment unit is fixed when the first focus adjustment unit operates. ing.

FIG. 2 is a diagram for explaining a general projector device as an image display device. FIG. 4 is a diagram for explaining focusing of a projected image. It is a figure for explaining trapezoidal distortion of a projection picture. It is a figure for explaining correction of keystone distortion. FIG. 7 is a diagram for explaining a case where correction of trapezoidal distortion in an image projection device using a mirror optical system is insufficient. FIG. 8 is a diagram for explaining a case where correction of trapezoidal distortion in an image projection device using a mirror optical system is insufficient. FIG. 9 is a diagram for explaining a case where a screen position changes in an image projection device using a mirror optical system. FIG. 7 is a diagram illustrating a main part of Reference Example 1. FIG. 9 is a diagram for explaining Reference Example 2. It is a figure for explaining an embodiment. FIG. 3 is a diagram for describing a specific example of a refractive optical system used in Reference Examples 1 and 2 and the embodiment. FIG. 3 is a diagram illustrating an example of a specific configuration of a refractive optical system. FIG. 4 is a diagram illustrating data of a refractive optical system portion of the projection optical system according to the first embodiment. FIG. 4 is a diagram showing data of the first embodiment. FIG. 4 is a diagram illustrating data of a mirror surface shape of a concave mirror according to the first embodiment. FIG. 2 is a diagram for explaining a projector device in which a projection optical system is loaded with an exterior OC. FIG. 2 is a diagram for explaining a projector device in which a projection optical system is loaded with an exterior OC.

  Hereinafter, embodiments and specific examples of a projection optical system and an image display device manufactured by the manufacturing method of the present invention will be described.

  In the following description, "DMD" is exemplified as a light valve as an image display element, but the image display element in the image display device manufactured by the manufacturing method of the present invention is not limited to DMD.

  That is, a light valve other than the DMD, for example, various known light valves such as an LD panel and an LCOS panel can be used for the image display device manufactured by the manufacturing method of the present invention.

  In addition, in order to avoid complication of the drawings, in the drawings used in the following description of the embodiments, a lamp light source as a light source and an illumination optical system for guiding illumination light from the lamp light source to a light valve for irradiation are shown. Omitted.

  Actually, the illumination light from the lamp light source LS as shown in FIG. 1 is used by an integrator rod IR, an illumination lens LN, a mirror M, and a curved mirror CM as an illumination optical system using a curved mirror, and a light valve LB (DMD). ) Is assumed.

  Of course, the type and configuration of the light source and the illumination light source are not limited to this case, and it goes without saying that an appropriate type is used according to the type and form of the image display element.

"Embodiment 1"
FIG. 8 shows a main part of Embodiment 1 of the projection optical system manufactured by the manufacturing method of the present invention.

  The light valve LB is a DMD and is held in the optical housing HS.

A lens barrel CL is connected to the optical housing HS via an intermediate member InA, and a plurality of lenses forming a “refractive optical system” of a projection optical system are arranged in the lens barrel CL.
In the first embodiment, the “refractive optical system” includes four lens groups, that is, a first lens group LI, a second lens group LII, a third lens group LIII, and a fourth lens group LIV from the light valve LB side. It is configured.

  Further, reference numeral RM indicates a “return mirror”, and reference numeral CNM indicates a concave mirror forming a “mirror optical system”.

  When illumination light from a light source (not shown) is applied to the image display surface of the DMD as the light valve LB by an illumination optical system (not shown), the reflected light from the image display surface is intensity-modulated by the display image displayed on the DMD. Incident on the “refractive optical system” of the projection optical system.

  The light beam emitted from the refraction optical system is reflected by the return mirror RM and becomes an imaged light beam when reflected by the concave mirror CNM. The light beam travels toward a projection surface (screen) (not shown), and a display image is displayed on the projection surface. An enlarged projected image is formed.

  The folding mirror RM is attached to the holder HL via an intermediate member InB.

  In such an “optical system that passes through the return mirror RM”, “the actual image of the display image is displayed on the optical path between the refractive optical system and the concave mirror RM” so that the degree of diffusion of the light reflected by the return mirror RM can be reduced. Is formed as an intermediate image to reduce the luminous flux once.

Focusing by focusing will be described.
Although not shown in FIG. 8, when the screen position is brought closer to the screen position SC (2) from the screen position SC (1) in FIG. 7, the projection image differs between “top and bottom of the screen”. In order to correct the focus adjustment amount, focusing is performed by a floating focus method.
In the first embodiment, of the four lens groups constituting the refractive optical system, the second lens group LII and the third lens group LIII are moved in the optical axis direction to perform focusing.

  FIG. 8 does not show the structure of the lens barrel CL in detail, but in order to move the second lens group LII and the third lens group LIII, for example, a cam groove is formed in the lens barrel CL and the second lens group is moved. A pin matching this cam groove is attached to each of the LII and the third lens group LIII, fitted into the cam groove, and the lens barrel CL is rotated, so that the second lens group LII and the third lens group LIII are different from each other. Can be moved in any direction.

  Here, the description is simplified by treating the lens barrel CL as one component, but in practice, a “more complicated configuration” using a plurality of components is generally employed.

  This cam mechanism is referred to as a “first focus adjustment unit”.

By the way, if a plurality of optical housings HS are manufactured, "dimension variation" naturally occurs in the product.
Therefore, when the lens barrel CL is directly assembled to the optical housing HS, the distance between the light valve LB and the first lens group LI in FIG. 8 varies according to “dimensional variation”.
In the first embodiment, if a plurality of lenses of the refractive optical system composed of the first to fourth lens groups LI to LIV and a plurality of concave mirrors CNM are manufactured, each has a “shape variation”. The "focal distance of the refractive optical system" varies, and the "optimum distance" between the light valve LB and the first lens unit LI varies.

  The “intermediate member InA” is arranged so that the distance between the light valve LB and the first lens group LI can be optimized even if there are these two types of “variation”.

  For example, a plurality of thin plates having a thickness of about 0.1 mm are used as the intermediate member InA, and the total thickness of the intermediate member InA is changed by changing the number of thin plates interposed between the optical housing HS and the lens barrel CL. Can be adjusted. In this way, the distance between the light valve LB and the first lens group LI can be adjusted in units of 0.1 mm.

  Alternatively, as another method, a plurality of plate members made of aluminum or the like having different thicknesses in units of 0.1 mm are prepared as the intermediate member InA, and for each combination of the optical housing HS and the refraction optical system, the “aluminum plate having an optimum thickness” Is selected and inserted, the distance between the light valve LB and the first lens group LI can be adjusted in units of 0.1 mm.

After adjusting the positional relationship between the optical housing HS and the lens barrel CL by the intermediate member InA, it is preferable to fix them to each other with screws or the like in order to fix the positional relationship.

  As described above, when the positional relationship between the light valve LB and the first lens unit LI is optimized by the intermediate member InA, the positional relationship between the fourth lens unit LIV and the concave mirror CNM is changed by the optimization operation. Relationship ".

  To correct this, the optical path length between the fourth lens group LIV and the concave mirror CNM is adjusted using the intermediate member InB interposed between the return mirror RM and the holder HL.

  Similarly to the intermediate member InA, the adjustment of the optical path length can be easily performed with high accuracy by using a plurality of thin plates or aluminum plates having different thicknesses.

  When a thin plate is used as the intermediate members InA and InB, if a plurality of position fixing points (for example, points fixed with screws) between the intermediate member InA and the optical housing HS or between the intermediate member InB and the holder HL are formed, each position can be adjusted. By changing the number of thin plates to be inserted at the fixed point, it is possible to correct "the tilt error between the light valve LB and the refractive optical system" and "the tilt error between the curved mirror CNM and the refractive optical system".

  The intermediate members InA and InB described above form a “second focus adjustment unit”.

  Since the intermediate member InA can be adjusted simply by sandwiching the intermediate member InA between the lens barrel CL and the optical housing HS, no special structure is required, and the optical housing HS and the lens barrel CL which are close to the light valve LB and have heat are in direct contact. By not performing this, heat is less likely to be transferred to the lens barrel CL, and a focus shift due to thermal expansion of the lens does not occur.

That is, the image display device according to mode 1 has the first and second focus adjustment units as described above.
In the first focus adjustment unit, when the distance between the projection surface and the concave mirror CNM is changed, the second lens unit LII and the third lens unit LIII in the refractive optical system are “displaced by different moving amounts”. Focusing is performed by the floating focus method.

  On the other hand, in the second focus adjustment unit, in the process of assembling the optical system of the image display device, by appropriately setting the positional relationship among the light valve, the refractive optical system, and the concave mirror (mirror optical system), in the reference state. The projected image is focused. After the adjustment of the positional relationship, the second focus adjustment unit is fixed.

"Embodiment 2"
Embodiment 2 will be described with reference to FIG.

  The second embodiment is a modification of the first embodiment described above. In the second focus adjustment unit, the “structure for adjusting the distance between the light valve LB and the first lens unit LI” is described as an intermediate member in the first embodiment. In this example, a screw structure (indicated by reference numeral “BS” in the drawing) is used instead of InA.

  The distance between the light valve LB and the first lens group LI is adjusted by the screw structure BS. Since the screw structure BS forms a “second focus adjustment unit” together with the intermediate member InB, the gap adjustment by the screw structure BS is performed in an assembly process of the optical system, and after the adjustment, the screw structure BS is fixed. Make adjustments by the user not easy.

  The second focus adjustment unit is not limited to the intermediate members InA and InB, the screw structure BS, and the like, and may have any structure as long as the same function as described above can be achieved.

"Reference example"
A reference example will be described with reference to FIG. In order to avoid complications, components that do not seem likely to be confused are denoted by the same reference numerals.

  In the embodiment whose configuration is shown in FIG. 10, the refractive optical system includes the first lens unit LI to the fourth lens unit LIV.

  In the reference example, “focusing by the floating focus method by moving the second lens unit LII and the third lens unit LIII” is performed. At this time, the fourth lens group LIV is fixed. That is, the second lens unit LII, the third lens unit LIII, and the mechanism for displacing them constitute a “first focus structure”.

  On the other hand, the “second focus structure” includes a fourth lens unit LIV and a structure for moving the fourth lens unit LIV in the optical axis direction.

By moving the fourth lens unit LIV in the optical axis direction, substantially the same effect as the above-described “focusing by whole extension” of the first and second embodiments can be obtained.
The movement of the fourth lens unit LIV is performed by a cam structure different from the cam structure for performing the second and third lens units LII and LIII, and is performed in an optical system assembly process. Make operation difficult.

  During the projection of the projection image, the second and third lens units LII and LIII are displaced and focused by the first focus structure. Since the first focus structure and the second focus structure are formed of separate cam mechanisms, the lens unit to be moved for focusing is small, and the influence of errors such as tilt caused by adjustment can be suppressed. There are aspects that are more favorable than whole feeding.

  However, when the fourth lens group LIV is moved in a direction away from the light valve LB as shown in FIG. 10, in the “optical structure using the folding mirror RM” as shown in FIGS. 8 and 9, the light is reflected by the folding mirror RM. It is necessary to prevent the reflected light from being blocked by the fourth lens group IV on the way to the concave mirror CNM.

  Specific examples of the refractive optical system used in the first and second embodiments and the reference example described above will be described with reference to FIG.

  11A and 11B, reference numerals 2 to 5 denote “parts of an illumination optical system”, reference numeral 1 denotes a “lamp light source” which is a light source, reference numeral 2 denotes an “integrator rod”, and reference numeral 3 denotes a “lens for illumination”. , 4 indicates a “mirror”, and 5 indicates a “curved mirror”. The curved mirror 5 is a “concave mirror having a spherical reflecting surface”.

  Reference numerals 6 to 10 denote “parts of the projection optical system”, reference numeral 6 denotes a dust-proof cover glass of the light valve, reference numeral 7 denotes a light valve main body, and reference numeral 8 denotes a “projection optical system”.

  In FIG. 11B, reference numeral 8-1 denotes a “refractive optical system”, reference numeral 9 denotes a dust-proof glass that protects a “concave mirror that is a free-form surface (concave mirror CNM in the above description)”, and reference numeral 10 denotes a dust-proof glass. The "lens barrel" holding the first to fourth lens groups is shown.

  The lens barrel 10 is carved with three different cam grooves so that three of the four lens groups can be "moved separately." Note that the "cam groove closest to the light valve 7" has nothing to do with focusing because the movement amount is 0.

FIG. 12 shows a specific configuration of the refractive optical system 8-1.
The refractive optical system 8-1 has a “four groups, eleven elements” configuration as shown in FIG. 12.
"Example 1"
One example of a specific example of the refractive optical system having the configuration shown in FIG. 12 is Example 1, and the data is shown in FIGS.
FIG. 13 shows the curvature radius and the surface interval of each surface in “mm units”, and shows the refractive index and Abbe number of the material. For an aperture stop, the aperture radius is shown. A radius of curvature: 0.000 indicates a radius of curvature: large, that is, a plane.
“Eccentric Y” indicates the amount of shift of the optical axis of the refractive optical system POSL to the negative side (the lower side in FIG. 5A) in the “Y direction (the vertical direction shown in FIG. 5A)”. "In units.

  “Eccentric α” indicates the amount of shift of the concave mirror CNM and the dustproof glass G of the projection optical system with respect to a plane including the optical axis (Z direction) and the lateral direction of the light valve LB in “mm” units.

  Further, the surface marked with “black circle” in the column of aspherical surface is an aspherical surface.

  In the field of the surface number, “LB (0)” is the image display surface of the light valve LB (DMD), and surface numbers “1, 2” are both surfaces of the cover glass CG. The surface numbers “4, 5” are the lens surfaces on the entrance side and the exit side of the lens closest to the image display surface of the refractive optical system, and these are both aspherical.

In the column of the radius of curvature, “1.0E + 18” means “1 × 10 ¹⁸ ”, and a surface having these radii of curvature is a “substantially flat surface”. The value of the radius of curvature is “paraxial radius of curvature” for an aspheric surface.

FIG. 14A shows aspherical surface data.
The aspherical surface has paraxial curvature (reciprocal of the paraxial curvature radius): C, elliptic constant (conic constant): K, higher order aspherical surface coefficient: E _2j (j = 2, 3, 4, 5, 6, 7, 7) , 8), coordinates in the direction orthogonal to the optical axis: H, depth in the direction of the optical axis: D, a well-known formula:
D = CH ² / [1+ {1- (1 + K) C ² H ² }]
+ ΣE _2j H ^2j (j = 1 to 8)
Is represented by

  For any aspherical surface used in the refractive optical system of the first embodiment, the elliptic constant: K is zero.

  FIG. 14B shows the first mirror, the second mirror (concave mirror CNM), and the first and second dustproof glasses on the basis of “the surface vertex of the lens surface closest to the first mirror (folding mirror)”. This is data of the X, Y, and Z positions of the plane, the screen distance 1 (the screen position SC (1)), and the screen distance 2 (the screen distance (2)).

  FIG. 14C shows specific movement amount data of each lens group in “mm units” when the screen distance is the screen distances 1 and 2.

  FIG. 15 shows “mirror shape data” of the concave mirror CNM.

  The mirror surface shape of the concave mirror CNM is a “free-form surface”, a paraxial radius of curvature on the optical axis: c, a conic constant: k, a higher-order coefficient: Cj (j = 2 to 72), and a distance in a direction perpendicular to the optical axis. : R, the "sag amount of the surface: z" parallel to the optical axis, the coordinates in the X direction: x, and the coordinates in the Y direction: y in FIG.

z = cr ² / [1+ {1- (1 + k) c ² r ² }]
_{^{+ ΣC j · x m y n}} (j = 2~72)
In FIG. 15, for example, “x ** 4 * y ** 7” using C40 as a coefficient represents “x ⁴ × y ⁷ ”.

The first lens group LI having a six-lens configuration is fixed at the time of focusing during use of the image display device. Done.
As shown in the specific data of the projection optical system shown in FIGS. 12 to 15, the projection optical system of the first embodiment is “non-telecentric on the object side”.

FIG. 16 and FIG. 17 show a projector device in which an exterior OC is loaded on the projection optical system.
The light valve LB, the refracting optical system POSL, the mirror optical system RM, and the CNM are housed in the exterior OC, and an image forming light beam is emitted through the cover glass CG to form an image on the screen SC.

  The “lens barrel mechanical structure” is set so that the “operation unit (focus lever)” of the first focus adjustment unit that performs focusing by the floating focus method is exposed outside the exterior OC. For example, in FIG. When the screen SC is moved in the up-down (Y) direction, the focus lever of the first focus adjustment unit is moved to perform the floating focus type focusing. Can be obtained.

  The “second focus adjustment unit” is housed and fixed inside the exterior OC and is not exposed to the outside, so that the user cannot easily operate the second focus adjustment unit.

  The second focus adjustment unit may be an “entire feeding mechanism that moves the entire refractive optical system in the normal direction of the light valve” when the folding mirror is not used.

  The whole feeding mechanism can be performed by screw rotation of a screw structure provided on a lens barrel that holds the refractive optical system.

  The whole feeding mechanism is configured as one or more intermediate members provided between a lens barrel holding a refractive optical system and an optical housing holding a light valve, and the lens barrel and the optical housing are assembled via the intermediate member. Can be found.

  In the case of the reference example, the second focus structure is a front group focus mechanism that moves the lens group farthest from the light valve among the lens groups inside the refractive optical system in the normal direction of the light valve.

  The image display device, when projecting and displaying a projection image on the projection surface, the light that has exited the light valve enters the mirror optical system via the refractive optical system, and is reflected on the mirror optical system, after which the light is projected onto the projection surface. The refracting optical system and the mirror optical system are arranged so as to face each other, and the projection optical system has a folding mirror for bending the optical path between the refractive optical system and the mirror optical system, and the folding mirror can adjust the installation position Can be held in a simple structure.

The structure that adjusts the installation position of the folding mirror can be configured by a holding component that holds the folding mirror and one or more intermediate members disposed between the folding mirrors.
It is preferable that the curved mirror of the mirror optical system is a concave mirror, and the real image of the image display element is formed as an intermediate image on the optical path between the refractive optical system and the mirror optical system by the refractive optical system.
As described above, the preferred embodiments of the present invention have been described. However, the present invention is not limited to the specific embodiments described above, and unless otherwise specified in the above description, the invention described in the claims. Various modifications and changes are possible within the scope of the spirit of the present invention.
The effects described in the embodiments of the present invention merely enumerate preferred effects resulting from the invention, and the effects of the invention are not limited to those described in the embodiments.

LB light valve
LI first lens system
LII Second lens system
LIII 3rd lens system
LIV title 4 lens system
RM folding mirror
CNM curved mirror
InA intermediate member
InB intermediate member
SC screen

JP 2009-251457 JP 2009-229736 A JP 2008-165187 A

Optical Technology Contact Vol. 39, no. 9 (2001)

Claims (9)

In order from the object side, a refractive optical system including a plurality of lens groups and a mirror optical system having a curved mirror are arranged, and the lens surface of the refractive optical system closest to the conjugate surface on the object side and the lens surface on the object side A part of the lens group in the refractive optical system is moved in the normal direction of the conjugate plane on the object side while maintaining the distance to the conjugate plane to correct different focus adjustment amounts at the top and bottom of the display screen. A first focus adjustment unit, and a second focus adjustment unit that maintains a distance between a lens surface closest to the object-side conjugate surface of the refractive optical system and the object-side conjugate surface at a predetermined distance. A method of manufacturing a projection optical system for enlarging and projecting an image of an object,
The second focus adjustment unit moves the lens of the refractive optical system to change and display the distance between the lens surface of the refractive optical system closest to the object-side conjugate plane and the object-side conjugate plane. After performing focus adjustment for adjusting the focus of the entire screen, fixing the predetermined distance between the lens surface of the refractive optical system closest to the conjugate plane on the object side and the conjugate plane on the object side. Of manufacturing projection optical system. The method for manufacturing a projection optical system according to claim 1,
A method of manufacturing a projection optical system, comprising: fixing a focus structure by a second focus adjustment unit so that the predetermined distance does not change. The method for manufacturing a projection optical system according to claim 1 or 2,
The method of manufacturing a projection optical system, wherein the second focus adjustment unit moves the entire refractive optical system in a direction normal to a conjugate plane on the object side. The method for manufacturing a projection optical system according to claim 3,
The method of manufacturing a projection optical system, wherein the second focus adjustment unit has a screw structure provided on a lens barrel that holds a refractive optical system. The method of manufacturing a projection optical system according to claim 1,
A method for manufacturing a projection optical system, comprising: a folding mirror for bending an optical path between a refractive optical system and a mirror optical system, wherein the folding mirror is held by a structure whose installation position is adjustable. The method for manufacturing a projection optical system according to claim 5,
A method for manufacturing a projection optical system, characterized in that a structure for adjusting the installation position of the return mirror includes a holding component for holding the return mirror and one or more intermediate members disposed between the return mirrors. The method for manufacturing a projection optical system according to any one of claims 1 to 6,
A method for manufacturing a projection optical system, characterized in that a curved mirror of a mirror optical system is a concave mirror, and a real image of an object is formed as an intermediate image on an optical path between the refractive optical system and the mirror optical system by a refractive optical system. In order from the object side, a refractive optical system including a plurality of lens groups and a mirror optical system having a curved mirror are arranged, and a distance between the lens surface of the refractive optical system closest to the image display element and the image display element. A first focus adjustment unit that moves a part of the lens groups in the refractive optical system in the normal direction of the image display element to correct different focus adjustment amounts at the top and bottom of the display screen while maintaining A second focus adjustment unit that maintains a distance between a lens surface of the refractive optical system closest to the conjugate plane on the object side and a conjugate plane on the object side at a predetermined distance, and displays the image on the image display element. A method for manufacturing an image display device having a projection optical system for projecting an enlarged image,
The second focus adjustment unit moves the lens of the refractive optical system to change and display the distance between the lens surface of the refractive optical system closest to the conjugate surface on the object side and the conjugate surface on the object side. After performing focus adjustment for adjusting the focus of the entire screen, fixing the predetermined distance between the lens surface of the refractive optical system closest to the conjugate surface on the object side and the conjugate surface on the object side. Of manufacturing an image display device. The method for manufacturing an image display device according to claim 8,
  The image display apparatus according to claim 1, wherein the second focus adjustment unit is at least one intermediate member provided between a lens barrel holding the refractive optical system and an optical housing holding the image display element. Production method.

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