JP6578662B2 - Projection optical system and projector - Google Patents

Description

  The present invention relates to a projection optical system and a projector, and is suitable for, for example, enlarging and projecting a display image of an image display element such as a digital micromirror device or an LCD (liquid crystal display) onto a screen. The present invention relates to a projection optical system having a wide angle of view and a projector equipped with the same.

  Conventionally, various lens systems have been proposed as projection optical systems for projectors (see, for example, Patent Documents 1 to 3). However, many problems need to be solved in order to realize a projection optical system having specifications according to the projector. A projector using three digital micromirror devices, for example, 3-chip DLP (digital light processing; a registered trademark of Texas Instruments, USA) requires a long lens back. In recent years, it has been demanded to project a larger image at a short distance, and in order to realize this, a wider angle of the projection optical system is required.

US7,009,765 B2 JP 2014-29392 A JP 2011-81415 A

  In the lens systems described in Patent Documents 1 and 2, a wide angle of view is realized using a relay lens, but the lens back is shortened. For this reason, when trying to cope with a long lens back as required by 3-chip DLP, the lens system becomes enormous, making it difficult to achieve both miniaturization and aberration correction. In the lens system described in Patent Document 3, the information about the lens back is insufficient, so that its optical performance is not clear, but it is difficult to achieve both size reduction and aberration correction.

  The present invention has been made in view of such a situation, and an object thereof is to provide a projection optical system in which various aberrations are satisfactorily corrected, a long lens back, a wide angle, and a small size are achieved. It is to provide a projector equipped with a projector.

To achieve the above object, a projection optical system according to a first aspect of the present invention is a projection optical system telecentric on the reduction side for enlarging and projecting an image displayed on an image display surface,
It consists of a first optical system and a second optical system in order from the magnification side, and each of the first optical system and the second optical system includes only a single lens as a lens element, and the second optical system forms an intermediate image. The first optical system magnifies and projects the intermediate image;
In the second optical system, the surface closest to the intermediate image is formed as a concave surface,
In the second optical system, the power of the lens element on the enlargement side closest to the point where the most off-axis principal ray intersects the optical axis is negative,
In the first optical system, the positive lens on the intermediate image side closest to the point where the most off-axis principal ray intersects the optical axis satisfies the following conditional expressions (6) and (7a):
The following conditional expression (1) is satisfied.
6.0 ≦ LB / | f | (1)
0.645 <θg_F + 0.001682 × νd <0.695 (6)
65.5 ≦ νd <100 (7a)
However,
LB: Lens back of the projection optical system (that is, air-converted back focus from the lens surface on the most reduction side to the image surface on the reduction side in the projection optical system),
f: focal length of the entire system,
θg_F: partial dispersion ratio of the lens material,
θg_F = (Ng−NF) / (NF−NC)
Ng: refractive index for g-line,
NF: refractive index for F-line,
NC: Refractive index for C-line,
νd: Abbe number of lens material,
It is .

A projection optical system of a second invention is a projection optical system telecentric on the reduction side for enlarging and projecting an image displayed on the image display surface,
It consists of a first optical system and a second optical system in order from the magnification side, and each of the first optical system and the second optical system includes only a single lens as a lens element, and the second optical system forms an intermediate image. The first optical system magnifies and projects the intermediate image;
In the second optical system, the surface closest to the intermediate image is formed as a concave surface,
In the first optical system, the positive lens on the intermediate image side closest to the point where the most off-axis principal ray intersects the optical axis satisfies the following conditional expressions (6) and (7a):
The following conditional expressions (2) and (3) are satisfied.
5.5 ≦ LB / | f | (2)
β + 100Pw−2 ≦ 0 (3)
0.645 <θg_F + 0.001682 × νd <0.695 (6)
65.5 ≦ νd <100 (7a)
However,
LB: Lens back of the projection optical system (that is, air-converted back focus from the lens surface on the most reduction side to the image surface on the reduction side in the projection optical system),
f: focal length of the entire system (when the projection optical system is a zoom lens, the focal length of the entire system at the wide angle end),
β: magnification of the second optical system,
Pw: the power of the lens element on the enlargement side closest to the point where the most off-axis principal ray intersects the optical axis in the second optical system,
θg_F: partial dispersion ratio of the lens material,
θg_F = (Ng−NF) / (NF−NC)
Ng: refractive index for g-line,
NF: refractive index for F-line,
NC: Refractive index for C-line,
νd: Abbe number of lens material,
It is.

A projection optical system according to a third aspect of the invention is characterized in that, in the first or second aspect of the invention, the following conditional expression (4) is satisfied.
−15 ≦ dis ≦ −3 (4)
However,
dis: distortion of intermediate image (%),
It is.

The projection optical system of the fourth invention, in the third invention, characterized in that the sign of the distortion of the intermediate image is changed.

The projection optical system according to a fifth aspect is characterized in that, in the fourth aspect , the sign of the distortion aberration of the intermediate image is switched at an image height of 20 to 7.5% of the maximum image height of the intermediate image. To do.

The projection optical system according to a sixth aspect of the present invention is the projection optical system according to any one of the first to fifth aspects, wherein all three lenses from the magnification side in the first optical system are negative meniscus lenses, and the three lenses At least one of them is an aspherical lens.

A projection optical system according to a seventh aspect is characterized in that, in the sixth aspect, the surface on the intermediate image side of the aspherical lens is an aspherical surface that satisfies the following conditional expression (5).
z (h1)> 3 (5)
However,
h1: the height from the optical axis of the most off-axis principal ray on the aspherical surface,
z (h1): Sag amount in the optical axis direction at the position of height h1 (based on the surface vertex),
And
The surface shape of the aspheric surface is defined by the following formula (AS) using an orthogonal coordinate system (x, y, z) having the surface vertex as the origin and the optical axis as the z axis.
z = (c · h ² ) / {1 + √ (1−ε · c ² · h ² )} + Σ (Aj · h ^j ) (AS)
here,
h: height in the direction perpendicular to the z-axis (h ² = x ² + y ² ),
z: sag amount in the optical axis direction at the position of height h (on the surface vertex basis),
c: curvature at the surface vertex,
ε: quadric surface parameter,
Aj: j-order aspheric coefficient (Σ represents the sum of the fourth to ∞ orders for j),
It is.

A projection optical system according to an eighth invention is characterized in that, in any one of the first to seventh inventions, the following conditional expression (8) is satisfied.
LB1 / LB ≦ 0.5 (8)
However,
LB: Lens back of the projection optical system (that is, air-converted back focus from the lens surface on the most reduction side to the image surface on the reduction side in the projection optical system),
LB1: Lens back of the first optical system (that is, air-converted back focus from the lens surface closest to the reduction side to the intermediate image plane in the first optical system),
It is.

A projection optical system according to a ninth invention is characterized in that, in any one of the first to eighth inventions, the following conditional expression (9) is satisfied.
0.5 <Fno / Fno1 <2.5 (9)
However,
Fno: F number of the projection optical system,
Fno1: F number of the first optical system,
It is.

A projection optical system according to a tenth aspect of the invention is characterized in that, in any one of the first to ninth aspects of the invention, the following conditional expression (10) is satisfied.
| Y1 / tan θ1 | ≧ 20 (10)
However,
Y1: the height of the most off-axis principal ray that passes through the lens positioned closest to the intermediate image of the first optical system,
θ1: an angle formed by the most off-axis principal ray passing through the lens located on the most intermediate image side of the first optical system and the optical axis,
The ray passing through the center between the upper ray and the lower ray is defined as the principal ray.

A projection optical system according to an eleventh invention is characterized in that, in any one of the first to tenth inventions, the following conditional expression (11) is satisfied.
| Y2 / tan θ2 | ≧ 500 (11)
However,
Y2: the height of the most off-axis principal ray that passes through the lens located closest to the image display surface of the second optical system,
θ2: an angle formed by the most off-axis principal ray passing through the lens located closest to the image display surface of the second optical system and the optical axis,
The ray passing through the center between the upper ray and the lower ray is defined as the principal ray.

A projection optical system according to a twelfth aspect of the invention is characterized in that, in any one of the first to eleventh aspects of the invention, the projection optical system has an aspherical surface so as to satisfy the following conditional expression (12).
1 ≦ n ≦ 7 (12)
However,
n: number of aspheric surfaces,
It is.

The projection optical system of a thirteenth aspect of the invention is characterized in that, in any one of the first to twelfth aspects of the invention, the projection optical system has an aspherical surface so as to satisfy the following conditional expression (13).
m + n ≦ 28 (13)
However,
m: number of lenses,
n: number of aspheric surfaces,
It is.

A projection optical system according to a fourteenth aspect of the invention is characterized in that, in any one of the first to thirteenth aspects of the invention, the following conditional expression (14) is satisfied.
2 ≦ LB / m ≦ 4 (14)
However,
LB: Lens back of the projection optical system (that is, air-converted back focus from the lens surface on the most reduction side to the image surface on the reduction side in the projection optical system),
m: number of lenses,
It is.

A projection optical system according to a fifteenth aspect of the present invention is the projection optical system according to any one of the first to fourteenth aspects, wherein at least one of the first and second optical systems moves for zooming. And

According to a sixteenth aspect of the present invention, in the fifteenth aspect of the invention, a part of the second optical system moves for zooming.

A projector according to a seventeenth aspect is the projection according to any one of the first to sixteenth aspects, wherein the image display element having the image display surface and an image displayed on the image display surface are enlarged and projected onto a screen surface. And an optical system.

According to an eighteenth aspect of the present invention, in the seventeenth aspect, the image display surface and the screen surface are both flat.

  According to the present invention, an intermediate image is formed by the second optical system, and a predetermined lens element and a concave surface are arranged in the second optical system, so that various aberrations are favorably corrected, In addition, it is possible to realize a projection optical system in which a long lens back, a wide angle and a small size are achieved, and a projector including the projection optical system.

The optical block diagram of 1st Embodiment (Example 1). The optical block diagram of 2nd Embodiment (Example 2). The optical block diagram of 3rd Embodiment (Example 3). The optical block diagram of 4th Embodiment (Example 4). The optical block diagram of 5th Embodiment (Example 5). The optical block diagram of 6th Embodiment (Example 6). The optical block diagram of 7th Embodiment (Example 7). The optical block diagram of 8th Embodiment (Example 8). The optical block diagram of 9th Embodiment (Example 9). FIG. 6 is an aberration diagram of Example 1. FIG. 6 is an aberration diagram of Example 2. FIG. 6 is an aberration diagram of Example 3. FIG. 6 is an aberration diagram of Example 4. FIG. 6 is an aberration diagram of Example 5. FIG. 10 is an aberration diagram of Example 6. FIG. 10 is an aberration diagram of Example 7. FIG. 10 is an aberration diagram of Example 8. FIG. 10 shows aberration diagrams at the telephoto end of Example 9. FIG. 10 shows aberration diagrams at the intermediate position of Example 9. FIG. 10 shows aberration diagrams at the wide-angle end of Example 9. FIG. 10 is a distortion aberration diagram of the intermediate image of Example 9. FIG. 2 is a schematic diagram illustrating an embodiment of a projector.

  Hereinafter, a projection optical system, a projector, and the like according to the present invention will be described. A projection optical system according to the present invention is a projection optical system that enlarges and projects an image displayed on an image display surface, and includes a first optical system and a second optical system in order from the enlargement side, and the second optical system includes An intermediate image is formed, the first optical system enlarges and projects the intermediate image, and a surface closest to the intermediate image in the second optical system is formed as a concave surface. Examples of the lens system constituting the projection optical system include a variable focal length lens system such as a zoom lens in addition to a single focus lens. The “enlargement side” is a direction in which the optical image is enlarged and projected onto a screen surface or the like, and the opposite direction is the “reduction side”, that is, an image display element that displays the original optical image (ie, the reduction side image surface). This is the direction in which (for example, a digital micromirror device) is arranged.

  As described above, by making the surface on the most intermediate image side concave in the second optical system, aberrations opposite to the curvature of field and distortion occurring on the intermediate image surface are generated and corrected. It is possible to realize a projection optical system in which aberrations are favorably corrected on the final image plane. The projection optical system can be divided into two types described below.

In the first type, the power of the lens element on the enlargement side closest to the point where the most off-axis principal ray intersects the optical axis in the second optical system is negative (power: an amount defined by the reciprocal of the focal length). The following conditional expression (1) is satisfied.
6.0 ≦ LB / | f | (1)
However,
LB: Lens back of the projection optical system (that is, air-converted back focus from the lens surface on the most reduction side to the image surface on the reduction side in the projection optical system),
f: focal length of the entire system,
It is.

  Conditional expression (1) defines conditions for ensuring a wide angle of view in a projection optical system with a large lens back. If the lower limit of conditional expression (1) is not reached, the focal length of the entire system increases and the field angle decreases. By making the power of the lens element on the enlargement side closest to the point where the most off-axis principal ray intersects the optical axis in the second optical system (corresponding to a lens Le in FIGS. When the height is raised with respect to the optical axis, various aberrations such as field curvature, distortion, and chromaticity of magnification can be suppressed. If the lens back is long, the angle formed by the off-axis principal ray with respect to the optical axis becomes small, so that a distance is required to raise the ray between the intermediate image planes from the lens Le (see FIGS. 1 to 9). However, if the negative lens is arranged as described above, the distance can be shortened and the optical axis can be reduced in size.

The second type is characterized in that the following conditional expressions (2) and (3) are satisfied.
5.5 ≦ LB / | f | (2)
β + 100Pw−2 ≦ 0 (3)
However,
LB: Lens back of the projection optical system (that is, air-converted back focus from the lens surface on the most reduction side to the image surface on the reduction side in the projection optical system),
f: focal length of the entire system (when the projection optical system is a zoom lens, the focal length of the entire system at the wide angle end),
β: magnification of the second optical system,
Pw: the power of the lens element on the enlargement side closest to the point where the most off-axis principal ray intersects the optical axis in the second optical system,
It is.

  Even in the second type, basically the same effect as in the first type can be obtained. However, the power of the lens element on the enlargement side (corresponding to a lens Le in FIGS. 1 to 9 described later) closest to the point where the most off-axis chief ray intersects the optical axis is particularly close to the relay magnification. In this case, since the intermediate image height is small, it is not necessarily negative, and the power Pw obtained from the conditional expression (3) is suitable in terms of aberration correction (correction of curvature of field, distortion, etc.).

  According to the characteristic configuration of the first and second types of projection optical systems described above, an intermediate image is formed by the second optical system, and a predetermined lens element or concave surface is disposed in the second optical system. Therefore, it is possible to realize a projection optical system in which various aberrations are satisfactorily corrected and a long lens back and a wide angle and a small size are achieved. If the projection optical system is used in a projector, the projector can contribute to high performance, high functionality, compactness, and the like. The conditions for achieving such effects in a well-balanced manner and achieving higher optical performance, downsizing, etc. will be described below.

It is desirable to satisfy the following conditional expression (4).
−15 ≦ dis ≦ −3 (4)
However,
dis: distortion of intermediate image (%),
It is.

  Since it is not necessary to completely suppress distortion on the intermediate image plane, it is not necessary to provide a lens for correcting aberrations in the intermediate image. This leads to reduction of the number of lenses and miniaturization of the projection optical system, so that the conditional expression (4) is satisfied. Is desirable. If the lower limit of conditional expression (4) is not reached, it will be difficult to correct distortion with the concave surface and the lens on the reduction side thereof, and good image formation will be difficult on the final image surface. If the upper limit of conditional expression (4) is exceeded, a lens for correcting distortion and curvature of field becomes necessary. For example, if correction of curvature of field and distortion is made in a balanced manner, the number of lenses increases and the projection optical system Will lead to an increase in size.

  In order to satisfy the conditional expression (4), it is desirable that the sign of the distortion of the intermediate image is switched, and the distortion of the intermediate image is 20 to 7.5% of the maximum image height of the intermediate image. It is more desirable that the sign of is switched.

In the first optical system, it is desirable that all three lenses from the magnification side are negative meniscus lenses, and at least one of the three lenses is an aspheric lens. It is further desirable that the surface on the intermediate image side of the aspheric lens is an aspheric surface that satisfies the following conditional expression (5).
z (h1)> 3 (5)
However,
h1: the height from the optical axis of the most off-axis principal ray on the aspherical surface,
z (h1): Sag amount in the optical axis direction at the position of height h1 (based on the surface vertex),
And
The surface shape of the aspheric surface is defined by the following formula (AS) using an orthogonal coordinate system (x, y, z) having the surface vertex as the origin and the optical axis as the z axis.
z = (c · h ² ) / {1 + √ (1−ε · c ² · h ² )} + Σ (Aj · h ^j ) (AS)
here,
h: height in the direction perpendicular to the z-axis (h ² = x ² + y ² ),
z: sag amount in the optical axis direction at the position of height h (on the surface vertex basis),
c: curvature at the surface vertex,
ε: quadric surface parameter,
Aj: j-order aspheric coefficient (Σ represents the sum of the fourth to ∞ orders for j),
It is.

  By arranging lenses with strong negative power side by side on the enlargement side, it becomes possible to widen the angle, and by including an aspheric lens, it becomes possible to effectively correct aberrations such as distortion and curvature of field. . Conditional expression (5) is an expression relating to the amount of sag of the aspherical shape. If the lower limit of conditional expression (5) is not reached, it is difficult to realize widening while correcting various aberrations. Therefore, satisfying conditional expression (5) makes it possible to achieve both wide angle and high performance.

In the first optical system, it is desirable that the closest positive lens on the intermediate image side from the point where the most off-axis principal ray intersects the optical axis satisfies the following conditional expression (6) and conditional expression (7) or (7a) .
0.645 <θg_F + 0.001682 × νd <0.695 (6)
60 <νd <100 (7)
65.5 ≦ νd <100 (7a)
However,
θg_F: partial dispersion ratio of the lens material,
θg_F = (Ng−NF) / (NF−NC)
Ng: refractive index for g-line,
NF: refractive index for F-line,
NC: Refractive index for C-line,
νd: Abbe number of lens material,
It is.

Conditional expression (6) and conditional expression (7) or (7a) are applied to a positive lens (corresponding to a lens Lp in FIGS. 1 to 9 described later) disposed in the vicinity of the aperture stop in the first optical system. If a glass material having anomalous dispersion as defined is used, the shift of the focal point of light having a long wavelength or short wavelength is reduced, so that axial chromatic aberration can be suppressed to a small value.

It is desirable to satisfy the following conditional expression (8).
LB1 / LB ≦ 0.5 (8)
However,
LB: Lens back of the projection optical system (that is, air-converted back focus from the lens surface on the most reduction side to the image surface on the reduction side in the projection optical system),
LB1: Lens back of the first optical system (that is, air-converted back focus from the lens surface closest to the reduction side to the intermediate image plane in the first optical system),
It is.

  If the upper limit of conditional expression (8) is exceeded, the lens back of the first optical system becomes longer, and the projection optical system becomes longer in the optical axis direction. Further, as the lens back of the first optical system becomes longer, the diameter of the front lens increases due to the characteristics of the lens type, so that it is difficult to reduce the size in the radial direction. If the diameter of the front lens is to be suppressed, field curvature or distortion may occur. Therefore, by satisfying conditional expression (8), it is possible to achieve both reduction in the radial direction of the projection optical system and correction of curvature of field and distortion.

It is desirable to satisfy the following conditional expression (9).
0.5 <Fno / Fno1 <2.5 (9)
However,
Fno: F number of the projection optical system,
Fno1: F number of the first optical system,
It is.

  If the upper limit of conditional expression (9) is exceeded, the lens in the vicinity of the intermediate image becomes large, and it becomes difficult to reduce the size in the radial direction. If an attempt is made to reduce the size in the radial direction, there is a risk of field curvature and distortion. If the lower limit of conditional expression (9) is not reached, the number of lenses near the intermediate image tends to increase in order to correct various aberrations (for example, spherical aberration and coma aberration). Therefore, by satisfying conditional expression (9), it is possible to achieve both reduction in the radial direction in the vicinity of the intermediate image and correction of curvature of field and distortion.

It is desirable to satisfy the following conditional expression (10).
| Y1 / tan θ1 | ≧ 20 (10)
However,
Y1: the height of the most off-axis principal ray that passes through the lens positioned closest to the intermediate image of the first optical system,
θ1: an angle formed by the most off-axis principal ray passing through the lens located on the most intermediate image side of the first optical system and the optical axis,
The ray passing through the center between the upper ray and the lower ray is defined as the principal ray.

  Conditional expression (10) defines a condition range that facilitates manufacture. Outside the range of conditional expression (10), the decentration sensitivity of the lens located in the vicinity of the intermediate image between the first and second optical systems becomes high, and there is a possibility that the productivity is deteriorated. That is, off-axis light rays are incident on the lens near the intermediate image at an angle, so that the performance of the second optical system is likely to deteriorate due to slight decentration of the lens, and one-sided blur and coma are likely to occur.

It is desirable to satisfy the following conditional expression (11).
| Y2 / tan θ2 | ≧ 500 (11)
However,
Y2: the height of the most off-axis principal ray that passes through the lens located closest to the image display surface of the second optical system,
θ2: an angle formed by the most off-axis principal ray passing through the lens located closest to the image display surface of the second optical system and the optical axis,
The ray passing through the center between the upper ray and the lower ray is defined as the principal ray.

  If the range of conditional expression (11) is not met, the angle of off-axis light becomes large, so the efficiency decreases particularly when color synthesis is performed with a dichroic prism or illumination light is captured with a TIR (Total Internal Reflection) prism. May be incurred.

It is desirable to have an aspherical surface so as to satisfy the following conditional expression (12).
1 ≦ n ≦ 7 (12)
However,
n: number of aspheric surfaces,
It is.

  If the lower limit of conditional expression (12) is not reached, the image plane property deteriorates, and it becomes difficult to obtain good imaging performance with a wide angle of view and a long lens back. If the upper limit of conditional expression (12) is exceeded, the number of aspheric surfaces will increase and manufacturing performance (for example, field curvature, distortion, spherical aberration, etc.) will not be stable, and the manufacturing cost will tend to increase.

It is desirable to have an aspherical surface so as to satisfy the following conditional expression (13).
m + n ≦ 28 (13)
However,
m: number of lenses,
n: number of aspheric surfaces,
It is.

  Exceeding the upper limit of conditional expression (13) means an increase in the number of aspheric surfaces or an increase in the number of lenses. Therefore, if the upper limit of conditional expression (13) is exceeded, the production performance (for example, field curvature, distortion, spherical aberration, etc.) becomes unstable due to an increase in the number of aspheric surfaces, or the production cost increases due to an increase in the number of lenses. Tend to be.

It is desirable to satisfy the following conditional expression (14).
2 ≦ LB / m ≦ 4 (14)
However,
LB: Lens back of the projection optical system (that is, air-converted back focus from the lens surface on the most reduction side to the image surface on the reduction side in the projection optical system),
m: number of lenses,
It is.

  If the upper limit of conditional expression (14) is exceeded, the number of lenses becomes relatively small with respect to the length of the lens back, so that an aspherical surface for correcting image plane characteristics and distortion is often used, and manufacturing is performed. The performance becomes unstable. If the lower limit of conditional expression (14) is not reached, the number of lenses increases and the cost tends to increase.

  The shorter the lens back LB is, the smaller the number of aspheric surfaces n and the number of lenses m are. However, when forming an intermediate image with a projection optical system having a long lens back LB that satisfies the conditional expressions (1) and (2), The number of spherical surfaces n and the number of lenses m are increased. If at least one of the conditional expressions (12) to (14) is satisfied, the manufacturing performance and the manufacturing cost can be well balanced.

  It is desirable that a part of at least one of the first and second optical systems moves for zooming, and it is further desirable that a part of the second optical system moves for zooming. A zoom lens used as a projection optical system will be described later with reference to a ninth embodiment (FIG. 9, Example 9).

  Next, a specific optical configuration of the projection optical system LN will be described with reference to the first to ninth embodiments. 1 to 8 are optical configuration diagrams respectively corresponding to the projection optical systems LN constituting the first to eighth embodiments, and the lens cross-sectional shape, lens arrangement, and the like of the projection optical system LN that is a single focus lens. An optical path or the like is shown by an optical cross section. FIG. 9 is an optical configuration diagram corresponding to each of the projection optical systems LN constituting the ninth embodiment. The lens sectional shape, lens arrangement, optical path, etc. of the projection optical system LN which is a zoom lens are shown at the telephoto end ( T), an intermediate position (M, intermediate focal length state), and a wide-angle end (W) are shown by optical cross sections. Note that a prism PR (for example, a TIR prism, a color separation / combination prism, etc.) and a cover glass CG of an image display element are located on the reduction side of the projection optical system LN.

  The projection optical system LN of the first to ninth embodiments includes a first optical system LN1 and a second optical system LN2 in order from the enlargement side, and an image (reduction side) displayed on the image display surface of the image display element. The second optical system LN2 forms an intermediate image IM1 of the image plane IM2, and the first optical system LN1 enlarges and projects the intermediate image IM1. In the second optical system LN2, the surface closest to the intermediate image IM1 is formed as a concave surface, and in the first to eighth embodiments, the most off-axis principal ray in the second optical system LN2 is the optical axis AX. The lens element Le on the enlargement side closest to the intersecting point has negative power. In the first to ninth embodiments, the positive lens Lp on the intermediate image IM1 side closest to the point where the most off-axis principal ray intersects the optical axis AX in the first optical system LN1 is a glass material having anomalous dispersion. It is made up of.

  The projection optical system LN of the ninth embodiment (FIG. 9) has, in order from the magnification side, a first lens group Gr1 having a positive power, a second lens group Gr2 having a positive power, and a negative power. And a sixth lens group Gr6 having a positive power, a fourth lens group Gr4 having a positive power, a fifth lens group Gr5 having a positive power, and a sixth lens group Gr6 having a positive power. The zoom lens for a projector is configured to perform zooming by moving the second lens group Gr2, the fourth lens group Gr4, and the fifth lens group Gr5 along the optical axis AX. That is, the ninth embodiment is a zoom lens having a six-group configuration having positive, negative, positive and positive power arrangements in order from the enlargement side. The first lens group Gr1, the third lens group Gr3, and the sixth lens group Gr6 The fixed group, the second lens group Gr2, the fourth lens group Gr4, and the fifth lens group Gr5 are moving groups. Since the zoom position of the first lens group Gr1 is fixed, a change in the overall length of the optical system due to zooming can be suppressed, and the zooming mechanism can be simplified because moving parts are reduced. The zoom positions of the prism PR and the cover glass CG located on the reduction side of the sixth lens group Gr6 are also fixed.

  Next, an embodiment of a projector provided with the projection optical system LN will be described. FIG. 22 shows a schematic configuration example of the projector PJ. The projector PJ includes a light source 1, an illumination optical system 2, a reflection mirror 3, a prism PR, an image display element (image forming element) 4, a control unit 5, an actuator 6, a projection optical system LN, and the like. The control unit 5 is a part that controls the entire projector PJ. The image display element 4 is an image modulation element (for example, a digital micromirror device) that modulates light to generate an image, and a cover glass CG is provided on the image display surface IM2 that displays an image. Yes.

  Light emitted from the light source 1 (for example, a white light source such as a xenon lamp or a laser light source) is guided to the image display element 4 by the illumination optical system 2, the reflection mirror 3, and the prism PR. It is formed. The prism PR is composed of, for example, a TIR prism (other color separation / combination prism or the like), and performs separation of illumination light and projection light. The image light formed by the image display element 4 is enlarged and projected toward the screen surface SC by the projection optical system LN. That is, the image IM2 displayed on the image display element 4 becomes the intermediate image IM1 by the second optical system LN2, and then is enlarged and projected on the screen surface SC by the first optical system LN1.

  The projector PJ is displayed on the image display element 4 that displays the image, the light source 1, the illumination optical system 2 that guides the light from the light source 1 to the image display element 4, and the image display element 4 as described above. A projection optical system LN that enlarges and projects an image onto the screen surface SC, but the projector to which the projection optical system LN is applicable is not limited to this. For example, if an image display element that displays an image by light emission of the image display surface itself is used, it is possible to eliminate illumination, and in that case, the projector is configured without using the light source 1 or the illumination optical system 2. Is possible.

  An actuator 6 that moves to the enlargement side or the reduction side along the optical axis AX is connected to each lens group that moves for zooming and focusing in the projection optical system LN. The actuator 6 is connected to a control unit 5 for performing movement control of the moving group. The control unit 5 and the actuator 6 may be moved manually without using them.

  Hereinafter, the configuration and the like of the projection optical system embodying the present invention will be described more specifically with reference to the construction data of the examples. Examples 1 to 9 (EX1 to 9) listed here are numerical examples corresponding to the first to ninth embodiments, respectively, and are optical configuration diagrams showing the first to ninth embodiments. (FIGS. 1 to 9) show the lens cross-sectional shape, lens arrangement, optical path, and the like of the corresponding Examples 1 to 9, respectively.

  In the construction data of each embodiment, as surface data, in order from the left column, the surface number i, the radius of curvature CR (mm), the axial top surface distance d (mm), the refractive index nd with respect to the d line (wavelength 587.56 nm), And Abbe number νd for d line. Note that Lp is the closest positive lens on the intermediate image side from the point where the most off-axis principal ray intersects the optical axis in the first optical system, and Le is the most from the point where the most off-axis principal ray intersects the optical axis in the second optical system. A lens element on the near magnification side, ST is an aperture stop, IM1 is an intermediate image plane, and IM2 is an image display plane.

The surface with * in the surface number i is an aspheric surface, and the surface shape is defined by the following formula (AS) using a local orthogonal coordinate system (x, y, z) with the surface vertex as the origin. The As aspheric data, an aspheric coefficient or the like is shown. It should be noted that the coefficient of the term not described in the aspherical data of each example is 0, and E−n = × 10 ⁻ⁿ for all data.
z = (c · h ² ) / {1 + √ (1−ε · c ² · h ² )} + Σ (Aj · h ^j ) (AS)
However,
h: height in the direction perpendicular to the z axis (optical axis AX) (h ² = x ² + y ² ),
z: the amount of sag in the direction of the optical axis AX at the position of the height h (based on the surface vertex),
c: curvature at the surface vertex (the reciprocal of the radius of curvature CR),
ε: quadric surface parameter,
Aj: j-order aspheric coefficient (Σ represents the sum of the fourth to ∞ orders for j),
It is.

  As various data, the focal length (f, mm) of the entire system, the image height (Y ′, mm), the half angle of view (ω, °), the F number (Fno) of the entire system, the lens back (LB, mm), focal lengths (f1, f2; mm) of the first and second optical systems, lens total length (TL, mm), and conditional expression related data. The conditional expression related data includes, for example, the F number (Fno1) of the first optical system, the lens back (LB1, mm) of the first optical system, and the height (Y1) of the most off-axis principal ray in the first and second optical systems. , Y2; mm), the angle (θ1, θ2; °) formed by the most off-axis principal ray in the first and second optical systems with the optical axis, and the height (h1) of the most off-axis principal ray in the aspherical surface from the optical axis. , Mm), the partial dispersion ratio (θg_F) of the positive lens LP in the first optical system, the magnification (β) of the second optical system, and the power (Pw) of the lens element Le in the second optical system. The lens back LB is a back focus in which the distance from the final lens surface to the paraxial image plane IM is expressed in terms of air length, and the total lens length is from the forefront (i = 1) of the projection optical system LN to the projection optical system LN. The lens back LB is added to the distance to the final surface. The image height Y ′ corresponds to half the diagonal length of the image display surface IM.

  For data that changes due to zooming, values at each zoom position T (TELE), M (MIDDLE), and W (WIDE) are shown. For example, a variable surface interval (di, i: surface number, mm) is indicated as a group interval, and a focal length (mm) of each lens group is indicated as zoom lens group data. Table 1 shows values corresponding to the conditional expressions for the respective examples.

  10 to 17 are aberration diagrams corresponding to Examples 1 to 8 (EX1 to EX8), respectively. In each of FIGS. 10 to 17, (A) is spherical aberration (mm), (B). Indicates astigmatism (mm), (C) indicates distortion (%), (D) indicates lateral chromatic aberration (mm), and (E) indicates distortion (%) of the intermediate image IM1 (H: incident height). (Mm), Y ′: image height (mm)). 18 to 21 are aberration diagrams corresponding to Example 9 (EX9). In each of FIGS. 18 to 21, (A) is spherical aberration (mm), and (B) is astigmatism (mm). ) And (C) show distortion aberration (%), and (D) shows lateral chromatic aberration (mm) (H: incident height (mm), Y ′: image height (mm)). FIG. 18 shows various aberrations (A) to (D) of Example 9 at the telephoto end (T), and FIG. 19 shows various aberrations (A) of Example 9 at the intermediate position (M, intermediate focal length state). FIG. 20 shows various aberrations (A) to (D) of Example 9 at the wide-angle end (W), and FIG. 21 shows distortion aberration (in the intermediate image IM1 of Example 9). %).

  In the spherical aberration diagram of (A), the solid line SA-e is the spherical aberration for the e line (wavelength 546.1 nm), the broken line SA-0.46 is the spherical aberration for the wavelength 460 nm, and the alternate long and short dash line SA-0.62 is for the wavelength 620 nm. Each represents a spherical aberration. In the astigmatism diagram of (B), mer-e, mer-0.46, mer-0.62 indicated by bold lines are meridional image planes, sag-e, sag-0.46, sag-0. 62 is a sagittal image plane, solid lines mer-e and sag-e are e-lines, broken lines mer-0.46 and sag-0.46 are wavelengths 460 nm, and alternate long and short dash lines mer-0.62 and sag-0.62 are Astigmatism with respect to a wavelength of 620 nm is shown. In the distortion diagrams of (C), (E), and FIG. 21, the solid line represents the distortion (%) with respect to the e-line. Are expressed on an e-line basis.

  In Examples 1 to 4, the first optical system LN1 extends from the first surface to the front of the intermediate image surface IM1, and the second optical system LN2 extends from the rear of the intermediate image surface IM1 to the 44th surface. The first to 44th surfaces are a projection optical system LN composed of a lens unit, and the 45th and subsequent surfaces are a prism PR and a cover glass CG of the image display element 4 (FIG. 22).

  In Examples 5 and 6, the first optical system LN1 is from the first surface to the front of the intermediate image surface IM1, and the second optical system LN2 is from the back of the intermediate image surface IM1 to the forty-second surface. The first surface to the forty-second surface are a projection optical system LN composed of a lens unit, and the 43rd and subsequent surfaces are a prism PR and a cover glass CG for the image display element 4 (FIG. 22).

  In Example 7, the first optical system LN1 extends from the first surface to the front of the intermediate image surface IM1, and the second optical system LN2 extends from the rear of the intermediate image surface IM1 to the 48th surface. The first surface to the 48th surface are the projection optical system LN composed of the lens unit, and the 49th surface and thereafter are the prism PR and the cover glass CG of the image display element 4 (FIG. 22).

  In Example 8, the first optical system LN1 is from the first surface to the front of the intermediate image surface IM1, and the second optical system LN2 is from the back of the intermediate image surface IM1 to the 50th surface. The first surface to the 50th surface are the projection optical system LN composed of the lens unit, and the 45th surface and subsequent surfaces are the prism PR and the cover glass CG of the image display element 4 (FIG. 22).

  In Example 9, the first optical system LN1 is from the first surface to the front of the intermediate image surface IM1, and the second optical system LN2 is from the back of the intermediate image surface IM1 to the 61st surface. The first to 61st surfaces are a projection optical system LN comprising a lens unit, and the 62nd and subsequent surfaces are a prism PR and a cover glass CG of the image display element 4 (FIG. 22). Sixteen first lens groups Gr1, three second lens groups Gr2, two third lens groups Gr3, three fourth lens groups Gr4, six fifth lens groups Gr5, and sixth lens group Gr6 Is a total of 31 lenses, and the second lens group Gr2, the fourth lens group Gr4, and the fifth lens group Gr5 move by zooming.

  When each embodiment is used as a projection optical system LN in a projector (for example, a liquid crystal projector) PJ, the screen surface (projected surface) SC is originally an image surface and the image display surface IM (for example, a liquid crystal panel surface) is an object surface. However, in each embodiment, the optical performance is evaluated on the image display surface (reduced side image surface) IM with the screen surface SC (FIG. 22) regarded as the object surface in terms of optical design. As can be seen from the obtained optical performance, the projection optical system of each embodiment can be suitably used not only as a projection lens for a projector but also as an imaging lens for an imaging device (for example, a video camera or a digital camera). It is.

Example 1
Unit: mm
Surface data
i CR d nd νd
1 58.547 5.739 1.58913 61.25
2 35.184 5.435
3 41.602 4.354 1.58913 61.25
4 25.819 5.350
5 * 56.921 2.506 1.51633 64.06
6 * 11.331 8.828
7 * 42.712 1.317 1.51633 64.06
8 * 20.352 9.120
9 (Lp) -34.744 6.295 1.49700 81.61
10 -10.751 0.200
11 79.926 7.457 1.43700 95.10
12 -18.003 1.296
13 -17.901 1.316 1.80518 25.46
14 140.541 0.822
15 66.870 8.860 1.49700 81.61
16 -37.286 0.200
17 * 18.777 13.858 1.49700 81.54
18 * -34.706 14.784
19 (IM1) ∞ 64.541
20 -157.017 6.771 1.91082 35.25
21 -65.154 0.200
22 26.501 11.613 1.71300 53.94
23 40.966 16.557
24 -330.809 1.534 1.80518 25.46
25 17.740 24.954
26 387.939 2.936 1.80611 40.73
27 -56.989 0.294
28 29.131 3.487 1.80610 33.27
29 117.985 10.894
30 (Le) -948.573 1.039 1.68893 31.16
31 21.756 5.969
32 (ST) ∞ 14.583
33 -59.640 1.517 1.80610 33.27
34 57.662 1.515
35 43.945 7.188 1.43700 95.10
36 -26.347 0.200
37 31.780 7.931 1.43700 95.10
38 -33.923 2.690
39 -28.694 1.447 1.91082 35.25
40 48.127 2.042
41 77.418 6.382 1.49700 81.61
42 -40.797 0.200
43 89.028 5.780 1.80518 25.46
44 -56.838 11.000
45 ∞ 54.000 1.51680 64.20
46 ∞ 5.000
47 ∞ 1.050 1.48749 70.44
48 ∞ 0.700
49 (IM2) ∞

Aspheric data
i ε A4 A6 A8
5 1.31275 3.47800E-05 -5.41392E-08 1.28233E-10
6 0.28275 -8.42394E-05 5.96325E-08 -2.23262E-10
7 -9.99999 -4.26553E-05 1.01913E-06 -2.78549E-09
8 5.00000 -2.12060E-05 3.57730E-09 1.26684E-08
17 -3.25098 8.23795E-06 -1.32287E-08 1.86688E-11
18 -5.00000 1.00000E-05 -8.70702E-09 2.01671E-11

Various data Focal length f -4.28
Statue height Y '9.62
Half angle of view ω 66.10
Fno 2.40
Fno1 5.07
LB 52.96
LB1 14.78
Y1 -18.42
θ1 -1.45
Y2 9.50
θ2 0.02
f1 9.67
f2 211.76
h1 12.84
TL 363.96
θg_F 0.54

Example 2
Unit: mm
Surface data
i CR d nd νd
1 59.484 4.290 1.58913 61.25
2 36.652 6.775
3 45.982 3.788 1.48749 70.44
4 26.061 5.201
5 * 58.885 2.375 1.51633 64.06
6 * 11.144 5.838
7 * 52.555 1.777 1.51633 64.06
8 * 25.011 11.292
9 (Lp) -241.842 5.956 1.49700 81.61
10 -13.327 0.200
11 -505.265 5.936 1.43700 95.10
12 -18.476 1.280
13 -18.402 1.310 1.80518 25.46
14 223.386 0.401
15 65.243 7.496 1.49700 81.61
16 -48.312 0.200
17 * 14.786 16.905 1.49700 81.54
18 * -23.464 12.268
19 (IM1) ∞ 66.477
20 -66.399 7.524 1.80611 40.73
21 -48.185 0.200
22 29.637 9.984 1.80611 40.73
23 37.341 17.832
24 -314.233 2.284 1.80518 25.46
25 25.857 15.679
26 -570.796 5.339 1.91082 35.25
27 -48.135 35.212
28 30.178 3.879 1.91082 35.25
29 149.510 9.653
30 (Le) 96.186 0.996 1.80610 33.27
31 17.332 10.289
32 (ST) ∞ 11.879
33 -63.055 1.580 1.90366 31.31
34 54.425 1.481
35 40.811 7.101 1.43700 95.10
36 -25.884 0.200
37 28.514 8.086 1.43700 95.10
38 -34.603 2.680
39 -29.031 1.420 1.91082 35.25
40 43.119 2.310
41 75.264 6.632 1.49700 81.61
42 -38.709 0.200
43 111.017 5.928 1.80518 25.46
44 -49.056 11.000
45 ∞ 54.000 1.51680 64.20
46 ∞ 5.000
47 ∞ 1.050 1.48749 70.44
48 ∞ 0.700
49 (IM2) ∞

Aspheric data
i ε A4 A6 A8
5 0.74460 4.13387E-05 -6.24739E-08 1.23924E-10
6 0.11206 -4.20273E-05 -1.23936E-07 2.10475E-10
7 3.38452 1.86974E-05 -7.04591E-08 2.41937E-10
8 5.00000 5.86556E-05 -3.98638E-07 1.03110E-09
17 -2.77340 7.93795E-06 -1.97806E-08 2.33288E-11
18 -5.00000 1.00000E-05 -1.90550E-08 2.97423E-11

Various data Focal length f -3.52
Statue height Y '9.62
Half angle of view ω 69.90
Fno 2.40
Fno1 5.65
LB 52.96
LB1 12.27
Y1 -19.40
θ1 -1.91
Y2 9.51
θ2 0.01
f1 8.74
f2 193.29
h1 12.48
TL 392.10
θg_F 0.54

Example 3
Unit: mm
Surface data
i CR d nd νd
1 61.259 4.674 1.58913 61.25
2 35.941 6.493
3 44.605 4.264 1.58913 61.25
4 25.615 5.697
5 * 100.872 2.378 1.51633 64.06
6 * 13.480 6.891
7 * 52.513 1.644 1.51633 64.06
8 * 25.244 11.918
9 (Lp) -82.203 6.618 1.49700 81.61
10 -12.888 0.200
11 85.009 7.325 1.43700 95.10
12 -20.682 1.403
13 -20.256 1.420 1.80518 25.46
14 108.005 0.200
15 49.645 7.546 1.49700 81.61
16 -69.386 0.200
17 * 15.078 15.155 1.49700 81.54
18 * -23.914 11.704
19 (IM1) ∞ 68.806
20 -125.356 8.704 1.80611 40.73
21 -56.352 0.202
22 26.741 12.366 1.74330 49.22
23 39.114 14.853
24 -31100.839 1.688 1.80518 25.46
25 17.579 28.390
26 -2106.296 3.999 1.91082 35.25
27 -68.829 4.676
28 37.757 2.838 1.91082 35.25
29 111.176 15.506
30 (Le) 76.779 1.137 1.80610 33.27
31 27.331 4.589
32 (ST) ∞ 15.126
33 -56.891 1.462 1.80610 33.27
34 43.562 1.716
35 38.442 7.351 1.43700 95.10
36 -27.769 0.200
37 29.068 8.409 1.43700 95.10
38 -34.212 3.002
39 -27.139 1.444 1.91082 35.25
40 50.076 2.046
41 82.876 6.479 1.49700 81.61
42 -38.970 0.200
43 113.036 5.751 1.80518 25.46
44 -51.050 11.000
45 ∞ 54.000 1.51680 64.20
46 ∞ 5.000
47 ∞ 1.050 1.48749 70.44
48 ∞ 0.700
49 (IM2) ∞

Aspheric data
i ε A4 A6 A8
5 4.02818 4.89444E-05 -8.92959E-08 1.68946E-10
6 0.39006 -4.76240E-05 2.14519E-09 -1.63440E-10
7 4.81187 -5.61596E-05 4.36035E-07 -7.57896E-10
8 4.99525 -4.12267E-05 8.35554E-08 2.46018E-09
17 -3.19637 9.18931E-06 -1.90003E-08 2.77221E-11
18 -5.00000 9.99327E-06 -8.57158E-09 2.76432E-11

Various data Focal length f -3.74
Statue height Y '9.62
Half angle of view ω 68.80
Fno 2.40
Fno1 5.21
LB 52.96
LB1 11.70
Y1 -18.28
θ1 -1.93
Y2 9.51
θ2 0.01
f1 8.54
f2 236.73
h1 12.86
TL 380.63
θg_F 0.54

Example 4
Unit: mm
Surface data
i CR d nd νd
1 54.499 4.973 1.58913 61.25
2 33.922 4.000
3 39.491 4.338 1.58913 61.25
4 24.755 4.456
5 * 39.765 3.046 1.51633 64.06
6 * 11.519 8.456
7 * 49.287 1.449 1.51633 64.06
8 * 18.781 10.398
9 (Lp) -26.771 5.597 1.49700 81.61
10 -10.560 0.976
11 71.054 7.243 1.43700 95.10
12 -18.451 3.082
13 -17.681 1.279 1.80518 25.46
14 167.357 0.612
15 62.214 10.531 1.49700 81.61
16 -37.984 3.242
17 * 22.927 14.426 1.49700 81.54
18 * -57.014 18.167
19 (IM1) ∞ 57.650
20 -158.131 4.473 1.91082 35.25
21 -66.526 0.215
22 26.705 11.019 1.71300 53.94
23 42.024 17.290
24 -453.750 1.493 1.80518 25.46
25 17.710 25.137
26 718.046 4.112 1.80611 40.73
27 -52.015 0.204
28 29.319 3.472 1.80610 33.27
29 126.725 11.120
30 (Le) -259.876 1.061 1.68893 31.16
31 21.823 4.826
32 (ST) ∞ 12.973
33 -61.236 1.602 1.80610 33.27
34 57.366 1.574
35 44.510 7.121 1.43700 95.10
36 -25.207 1.193
37 32.665 7.740 1.43700 95.10
38 -33.452 2.606
39 -28.820 1.435 1.91082 35.25
40 48.608 2.074
41 81.611 6.293 1.49700 81.61
42 -40.049 0.697
43 88.984 6.323 1.80518 25.46
44 -57.030 11.000
45 ∞ 54.000 1.51680 64.20
46 ∞ 5.000
47 ∞ 1.050 1.48749 70.44
48 ∞ 0.700
49 (IM2) ∞

Aspheric data
i ε A4 A6 A8
5 -0.85496 3.06830E-05 -2.95755E-08 1.26558E-10
6 0.28808 -8.60720E-05 6.47192E-08 -2.24535E-10
7 -7.80147 -3.67633E-05 1.03547E-06 -3.20019E-09
8 4.99812 1.59315E-05 -2.56076E-07 1.83558E-08
17 -2.67820 7.86312E-06 -1.22323E-08 1.64637E-11
18 -4.99887 9.87186E-06 -1.21852E-08 2.13268E-11

Various data Focal length f -5.58
Statue height Y '9.62
Half angle of view ω 59.90
Fno 2.40
Fno1 5.18
LB 52.96
LB1 18.17
Y1 -19.12
θ1 -1.03
Y2 9.50
θ2 0.03
f1 13.24
f2 205.81
h1 11.92
TL 363.93
θg_F 0.54

Example 5
Unit: mm
Surface data
i CR d nd νd
1 45.192 4.306 1.58913 61.25
2 26.770 10.066
3 25.541 2.889 1.80860 40.42
4 * 11.217 7.470
5 36.448 1.325 1.72916 54.67
6 10.389 5.990
7 11.786 1.800 1.51633 64.06
8 * 12.808 15.169
9 (Lp) 161.294 5.837 1.49700 81.61
10 -15.921 1.197
11 218.787 6.807 1.59349 67.00
12 -15.009 0.010
13 -15.009 1.446 1.90366 31.31
14 -34.654 27.025
15 -88.374 5.236 1.74320 49.29
16 * -19.440 16.343
17 (IM1) ∞ 21.522
18 -17.271 2.306 1.69680 55.46
19 -123.394 7.390
20 -86.937 13.519 1.78590 43.93
21 -30.851 0.200
22 -190.846 5.409 1.90366 31.31
23 -69.061 29.442
24 -53.481 3.533 1.80810 22.76
25 -105.251 0.200
26 88.578 8.053 1.80611 40.73
27 -133.025 45.362
28 (Le) -34.168 1.557 1.51680 64.20
29 -90.469 18.359
30 (ST) ∞ 5.640
31 -105.027 1.494 1.91082 35.25
32 25.889 0.010
33 25.889 7.633 1.59349 67.00
34 -34.514 9.076
35 71.723 6.038 1.49700 81.61
36 -28.737 1.071
37 -38.141 1.374 1.91082 35.25
38 39.510 0.010
39 39.510 6.248 1.59349 67.00
40 -60.296 14.582
41 76.755 5.398 1.78472 25.72
42 -80.988 11.000
43 ∞ 54.000 1.51680 64.20
44 ∞ 5.000
45 ∞ 1.050 1.48749 70.44
46 ∞ 0.700
47 (IM2) ∞

Aspheric data
i ε A4 A6 A8
4 0.12624 -1.08863E-06 8.51319E-09 -1.31530E-10
8 0.79920 1.37778E-04 5.04370E-07 6.17016E-09
16 -0.71471 1.02304E-05 3.83880E-08 -6.82587E-11

Various data Focal length f -6.13
Statue height Y '9.62
Half angle of view ω 57.50
Fno 2.40
Fno1 3.04
LB 52.96
LB1 16.34
Y1 -11.22
θ1 -1.25
Y2 9.53
θ2 0.06
f1 8.42
f2 292.65
h1 10.74
TL 392.30
θg_F 0.54

Example 6
Unit: mm
Surface data
i CR d nd νd
1 61.959 5.700 1.58913 61.25
2 33.847 13.177
3 28.340 2.370 1.80860 40.42
4 * 9.612 9.182
5 34.787 1.451 1.72916 54.67
6 10.735 5.848
7 12.287 1.800 1.51633 64.06
8 * 16.104 12.533
9 (Lp) 64.289 7.513 1.49700 81.61
10 -15.126 0.200
11 141.475 9.686 1.59349 67.00
12 -13.117 0.010
13 -13.117 1.193 1.90366 31.31
14 -38.745 18.213
15 -74.148 5.868 1.74320 49.29
16 * -15.080 13.917
17 (IM1) ∞ 21.832
18 -17.724 2.434 1.69680 55.46
19 -100.396 7.590
20 -78.005 14.071 1.78590 43.93
21 -31.116 0.204
22 -170.992 5.090 1.90366 31.31
23 -71.145 37.556
24 -52.286 3.253 1.80810 22.76
25 -110.787 0.201
26 82.391 8.537 1.80611 40.73
27 -123.020 43.277
28 (Le) -29.006 1.552 1.51680 64.20
29 -61.684 18.373
30 (ST) ∞ 14.087
31 -95.522 1.702 1.91082 35.25
32 27.150 0.010
33 27.150 7.379 1.59349 67.00
34 -32.374 6.469
35 93.107 6.713 1.49700 81.61
36 -27.175 1.051
37 -33.790 1.490 1.91082 35.25
38 48.224 0.010
39 48.224 5.676 1.59349 67.00
40 -67.980 5.165
41 63.038 5.854 1.78472 25.72
42 -82.006 11.000
43 ∞ 54.000 1.51680 64.20
44 ∞ 5.000
45 ∞ 1.050 1.48749 70.44
46 ∞ 0.700
47 (IM2) ∞

Aspheric data
i ε A4 A6 A8
4 0.27160 -3.85848E-05 1.03362E-08 -6.27716E-10
8 2.93163 1.15730E-04 8.11245E-08 7.60309E-09
16 -0.26505 1.62003E-05 9.20255E-08 -2.01263E-10

Various data Focal length f -4.33
Statue height Y '9.62
Half angle of view ω 65.90
Fno 2.40
Fno1 3.21
LB 52.96
LB1 13.92
Y1 -11.71
θ1 -1.25
Y2 9.57
θ2 0.05
f1 6.09
f2 130.11
h1 11.66
TL 392.20
θg_F 0.54

Example 7
Unit: mm
Surface data
i CR d nd νd
1 76.385 4.180 1.58913 61.25
2 33.384 8.378
3 47.494 2.802 1.58913 61.25
4 24.371 6.800
5 33.582 3.000 1.58913 61.15
6 * 10.943 16.564
7 -28.321 1.364 1.83400 37.34
8 24.874 5.000
9 116.305 7.195 1.80610 33.27
10 -25.623 8.000
11 * -18.114 3.000 1.52510 56.38
12 -16.751 1.000
13 21.580 3.442 1.53172 48.84
14 57.351 17.792
15 (Lp) 76.848 10.110 1.60300 65.44
16 -13.604 0.010
17 -13.604 1.229 1.76182 26.61
18 42.507 1.478
19 35.860 8.479 1.49700 81.61
20 -32.923 8.131
21 * 111.760 4.700 1.52510 56.38
22 -34.466 5.801
23 86.751 3.747 1.84666 23.78
24 -269.956 11.180
25 (IM1) ∞ 37.529
26 -69.506 2.061 1.72825 28.32
27 -299.923 6.472
28 -42.301 2.899 1.84666 23.78
29 -326.909 5.514
30 -67.459 9.582 1.83400 37.34
31 -30.867 0.200
32 45.682 9.667 1.69680 55.46
33 1914.605 53.644
34 (Le) -20.355 1.287 1.75520 27.53
35 -39.953 4.654
36 (ST) ∞ 15.518
37 -96.759 1.171 1.91082 35.25
38 26.640 0.010
39 26.640 7.660 1.60 300 65.44
40 -35.729 0.200
41 37.053 8.557 1.49700 81.61
42 -28.439 1.897
43 -29.053 1.511 1.91082 35.25
44 35.638 0.010
45 35.638 7.482 1.60300 65.44
46 -69.499 0.588
47 149.202 6.750 1.80810 22.76
48 -39.622 11.000
49 ∞ 54.000 1.51680 64.2
50 ∞ 5.000
51 ∞ 1.050 1.48749 70.44
52 ∞ 0.700
53 (IM2) ∞

Aspheric data
i ε A4 A6 A8
6 -1.96320E-05 -1.06740E-07 2.77818E-10 -1.64302E-12
11 2.82626E-06 2.03951E-08 -3.45541E-11 2.89205E-13
21 -6.48798E-05 5.73537E-08 -2.85311E-10 7.67058E-14

Various data Focal length f -4.31
Statue height Y '9.62
Half angle of view ω 65.90
Fno 2.40
Fno1 3.75
LB 52.96
LB1 11.18
Y1 -13.33
θ1 0.43
Y2 9.48
θ2 0.04
f1 5.94
f2 83.22
h1 11.79
TL 392.21
θg_F 0.54

Example 8
Unit: mm
Surface data
i CR d nd νd
1 71.279 4.290 1.58913 61.25
2 35.051 8.517
3 49.485 3.351 1.58913 61.25
4 25.194 7.285
5 36.040 2.800 1.74320 49.29
6 * 9.835 15.518
7 -45.873 1.529 1.49700 81.61
8 23.891 3.898
9 33.964 5.967 1.91082 35.25
10 -61.992 1.000
11 12.482 2.000 1.51633 64.06
12 * 10.138 16.470
13 (Lp) 49.304 6.012 1.49700 81.61
14 -16.349 1.369
15 -4320.936 10.082 1.61800 63.39
16 -11.266 0.010
17 -11.266 1.063 1.78472 25.72
18 40.547 1.454
19 32.896 9.030 1.69350 53.18
20 * -12.062 11.500
21 (IM1) ∞ 18.881
22 -13.665 1.832 1.80810 22.76
23 -125.152 4.925
24 -77.478 12.381 1.78590 43.93
25 -26.225 7.106
26 -38.569 5.560 1.69680 55.46
27 -31.990 0.674
28 120.716 8.614 1.80000 29.84
29 -113.185 6.644
30 -51.995 4.260 1.48749 70.44
31 -78.925 57.967
32 46.001 5.786 1.49700 81.61
33 -69.396 0.200
34 25.458 7.810 1.61800 63.39
35 -37.193 0.010
36 (Le) -37.193 1.178 1.75520 27.53
37 13.472 13.312
38 (ST) ∞ 8.686
39 -37.978 1.129 1.80611 40.73
40 24.264 0.010
41 24.264 6.255 1.60311 60.69
42 -102.580 1.244
43 101.685 8.396 1.49700 81.61
44 -20.907 12.698
45 -31.761 1.432 1.80611 40.73
46 43.667 0.010
47 43.667 7.514 1.60311 60.69
48 -40.773 3.000
49 63.442 6.204 1.80810 22.76
50 -87.491 11.000
51 ∞ 54.000 1.51680 64.2
52 ∞ 5.000
53 ∞ 1.050 1.48749 70.44
54 ∞ 0.700
55 (IM2) ∞

Aspheric data
i ε A4 A6 A8
6 -3.41665E-02 -9.28345E-07 5.43240E-08 -1.12205E-10
12 1.14204E + 00 2.11924E-05 6.52602E-08 8.39248E-10
20 5.45504E-01 1.67316E-04 -2.15894E-07 7.13643E-10

Various data Focal length f -4.32
Statue height Y '9.62
Half angle of view ω 65.80
Fno 2.40
Fno1 2.28
LB 52.96
LB1 12.18
Y1 -8.29
θ1 -1.23
Y2 9.65
θ2 -0.05
f1 4.50
f2 195.16
h1 11.83
TL 390.82
θg_F 0.54
β 0.95
Pw -0.0281

Example 9
Unit: mm
Surface data
i CR d nd νd
1 69.012 5.200 1.65844 50.85
2 40.721 11.489
3 * 101.897 5.000 1.49270 57.49
4 * 30.737 12.047
5 79.286 3.000 1.80611 40.73
6 39.270 20.000
7 -30.928 3.000 1.84666 23.78
8 115.236 17.736
9 -228.143 10.000 1.80518 25.46
10 -56.138 0.300
11 422.294 10.000 1.74330 49.22
12 -92.504 72.431
13 48.139 3.000 1.72342 37.99
14 32.697 3.461
15 68.331 3.972 1.43700 95.10
16 -261.896 0.100
17 (ST) ∞ 22.021
18 (Lp) 47.517 7.000 1.43700 95.10
19 -105.765 0.100
20 51.327 3.000 1.88300 40.80
21 29.323 2.495
22 33.818 9.200 1.43700 95.10
23 -109.091 0.300
24 24.789 8.000 1.43700 95.10
25 -112.054 3.323
26 -166.879 3.000 1.88300 40.80
27 20.446 9.942
28 57.954 6.000 1.43700 95.10
29 -192.422 1.000
30 42.132 6.000 1.43700 95.10
31 93.200 1.000
32 25.382 7.000 1.43700 95.10
33 ∞ 5.000
34 (IM1) ∞ Variable
35 -31.866 2.500 1.60342 38.01
36 71.282 5.000
37 -114.000 6.000 1.74330 49.22
38 -39.084 8.275
39 208.406 10.000 1.58913 61.25
40 -41.828 Variable
41 -36.483 3.000 1.51680 64.20
42 77.850 5.449
43 112.624 13.273 1.43700 95.10
44 -38.175 variable
45 -38.632 3.000 1.51823 58.96
46 166.903 2.500
47 (Le) 198.192 18.039 1.43700 95.10
46 -45.119 0.100
47 437.401 8.562 1.43700 95.10
48 -139.113 Variable
49 72.201 11.675 1.43700 95.10
50 -490.574 7.282
51 61.366 11.722 1.43700 95.10
52 -164.681 2.800
53 -117.362 3.500 1.51680 64.20
54 34.532 16.000
55 -49.665 3.500 1.51680 64.20
56 139.611 3.250
57 86.409 11.691 1.43700 95.10
58 -56.160 43.273
59 178.899 7.000 1.49700 81.61
60 -426.072 variable
61 156.789 6.500 1.49700 81.61
62 ∞ 15.000
63 ∞ 85.000 1.51680 64.20
64 ∞ 5.000
65 ∞ 3.000 1.48749 70.44
66 ∞
67 (IM2) ∞

Aspheric data
i ε A4 A6 A8
3 3.79632E + 00 1.01159E-05 -9.97306E-09 5.24354E-12
4 1.03901E + 00 9.70738E-06 -1.96349E-08 2.13512E-11

Aspheric data
i A10 A12 A14
3 9.29612E-16 -2.06594E-18 6.78815E-22
4 -5.27747E-14 6.54688E-17 -4.20248E-20

Various data
TELE MIDDLE WIDE
Focal length f -16.99 -15.28 -13.81
Statue height Y '15.60
Half angle of view ω 42.6 45.6 48.5
Fno 3.11 2.79 2.51
Fno1 1.91 1.91 1.91
LB 78.50
LB1 5.00

Various data
TELE MIDDLE WIDE
Group spacing
d34 20.530 24.760 29.639
d40 32.859 28.626 23.750
d44 8.650 18.646 29.895
d48 3.343 14.278 22.278
d60 53.969 33.039 13.789

Various data
TELE MIDDLE WIDE
Y1 -9.67 -10.81 -12.06
θ1 3.61 4.37 5.85
Y2 13.42 13.91 15.18
θ2 1.50 1.15 0.23
h1 20.58 22.24 23.75
β 0.61 0.68 0.76
Pw 0.0041
TL 405.84
θg_F 0.54

Zoom lens group data group (surface) Focal length
1 (1-33) 10.52
2 (35-40) 75.60
3 (41-44) -572.64
4 (45-48) 332.76
5 (49-60) 245.13
6 (61-62) 314.55

LN projection optical system LN1 first optical system LN2 second optical system Gr1 to Gr6 first to sixth lens groups Le lens element Lp positive lens ST aperture stop IM1 intermediate image (intermediate image plane)
IM2 Image display surface (reduction side image surface)
PJ projector PR prism SC screen surface 1 light source 2 illumination optical system 3 reflecting mirror 4 image display element 5 control unit 6 actuator AX optical axis

Claims (18)

A telecentric projection optical system on the reduction side for enlarging and projecting an image displayed on the image display surface,
It consists of a first optical system and a second optical system in order from the magnification side, and each of the first optical system and the second optical system includes only a single lens as a lens element, and the second optical system forms an intermediate image. The first optical system magnifies and projects the intermediate image;
In the second optical system, the surface closest to the intermediate image is formed as a concave surface,
In the second optical system, the power of the lens element on the enlargement side closest to the point where the most off-axis principal ray intersects the optical axis is negative,
In the first optical system, the positive lens on the intermediate image side closest to the point where the most off-axis principal ray intersects the optical axis satisfies the following conditional expressions (6) and (7a):
A projection optical system satisfying the following conditional expression (1):
6.0 ≦ LB / | f | (1)
0.645 <θg_F + 0.001682 × νd <0.695 (6)
65.5 ≦ νd <100 (7a)
However,
LB: Lens back of the projection optical system (that is, air-converted back focus from the lens surface on the most reduction side to the image surface on the reduction side in the projection optical system),
f: focal length of the entire system,
θg_F: partial dispersion ratio of the lens material,
θg_F = (Ng−NF) / (NF−NC)
Ng: refractive index for g-line,
NF: refractive index for F-line,
NC: Refractive index for C-line,
νd: Abbe number of lens material,
It is. A telecentric projection optical system on the reduction side for enlarging and projecting an image displayed on the image display surface,
It consists of a first optical system and a second optical system in order from the magnification side, and each of the first optical system and the second optical system includes only a single lens as a lens element, and the second optical system forms an intermediate image. The first optical system magnifies and projects the intermediate image;
In the second optical system, the surface closest to the intermediate image is formed as a concave surface,
In the first optical system, the positive lens on the intermediate image side closest to the point where the most off-axis principal ray intersects the optical axis satisfies the following conditional expressions (6) and (7a):
A projection optical system satisfying the following conditional expressions (2) and (3):
5.5 ≦ LB / | f | (2)
β + 100Pw−2 ≦ 0 (3)
0.645 <θg_F + 0.001682 × νd <0.695 (6)
65.5 ≦ νd <100 (7a)
However,
LB: Lens back of the projection optical system (that is, air-converted back focus from the lens surface on the most reduction side to the image surface on the reduction side in the projection optical system),
f: focal length of the entire system (when the projection optical system is a zoom lens, the focal length of the entire system at the wide angle end),
β: magnification of the second optical system,
Pw: the power of the lens element on the enlargement side closest to the point where the most off-axis principal ray intersects the optical axis in the second optical system,
θg_F: partial dispersion ratio of the lens material,
θg_F = (Ng−NF) / (NF−NC)
Ng: refractive index for g-line,
NF: refractive index for F-line,
NC: Refractive index for C-line,
νd: Abbe number of lens material,
It is. The following conditional expression (4) and satisfies the claim 1 or 2, wherein the projection optical system;
−15 ≦ dis ≦ −3 (4)
However,
dis: distortion of intermediate image (%),
It is. The projection optical system according to claim 3, wherein the sign of distortion of the intermediate image is switched. 5. The projection optical system according to claim 4 , wherein the sign of distortion aberration of the intermediate image is switched at an image height of 20 to 7.5% of the maximum image height of the intermediate image. A three lenses are all negative meniscus lens from the magnification side in the first optical system, it claims 1-5, characterized in that at least one aspherical lens of three lenses 2. A projection optical system according to item 1. The projection optical system according to claim 6, wherein the surface on the intermediate image side of the aspheric lens is an aspheric surface satisfying the following conditional expression (5):
z (h1)> 3 (5)
However,
h1: the height from the optical axis of the most off-axis principal ray on the aspherical surface,
z (h1): Sag amount in the optical axis direction at the position of height h1 (based on the surface vertex),
And
The surface shape of the aspheric surface is defined by the following formula (AS) using an orthogonal coordinate system (x, y, z) having the surface vertex as the origin and the optical axis as the z axis.
z = (c · h ² ) / {1 + √ (1−ε · c ² · h ² )} + Σ (Aj · h ^j ) (AS)
here,
h: height in the direction perpendicular to the z-axis (h ² = x ² + y ² ),
z: sag amount in the optical axis direction at the position of height h (on the surface vertex basis),
c: curvature at the surface vertex,
ε: quadric surface parameter,
Aj: j-order aspheric coefficient (Σ represents the sum of the fourth to ∞ orders for j),
It is. The following conditional expression (8) be satisfied, characterized in claims 1-7 projection optical system according to any one of;
LB1 / LB ≦ 0.5 (8)
However,
LB: Lens back of the projection optical system (that is, air-converted back focus from the lens surface on the most reduction side to the image surface on the reduction side in the projection optical system),
LB1: Lens back of the first optical system (that is, air-converted back focus from the lens surface closest to the reduction side to the intermediate image plane in the first optical system),
It is. The projection optical system according to any one of claims 1 to 8, characterized by satisfying the following conditional expression (9);
0.5 <Fno / Fno1 <2.5 (9)
However,
Fno: F number of the projection optical system,
Fno1: F number of the first optical system,
It is. The projection optical system according to any one of claims 1 to 9, characterized by satisfying the following conditional expression (10);
| Y1 / tan θ1 | ≧ 20 (10)
However,
Y1: the height of the most off-axis principal ray that passes through the lens positioned closest to the intermediate image of the first optical system,
θ1: an angle formed by the most off-axis principal ray passing through the lens located on the most intermediate image side of the first optical system and the optical axis,
The ray passing through the center between the upper ray and the lower ray is defined as the principal ray. The projection optical system according to any one of claims 1 to 10, characterized by satisfying the following conditional expression (11);
| Y2 / tan θ2 | ≧ 500 (11)
However,
Y2: the height of the most off-axis principal ray that passes through the lens located closest to the image display surface of the second optical system,
θ2: an angle formed by the most off-axis principal ray passing through the lens located closest to the image display surface of the second optical system and the optical axis,
The ray passing through the center between the upper ray and the lower ray is defined as the principal ray. The projection optical system according to any one of claims 1 to 11 , wherein the projection optical system has an aspheric surface so as to satisfy the following conditional expression (12):
1 ≦ n ≦ 7 (12)
However,
n: number of aspheric surfaces,
It is. The following conditional expression according to any one of claims 1 to 12, characterized in that it has an aspherical surface to satisfy (13) a projection optical system;
m + n ≦ 28 (13)
However,
m: number of lenses,
n: number of aspheric surfaces,
It is. The projection optical system according to any one of claims 1 to 13, characterized by satisfying the following condition (14);
2 ≦ LB / m ≦ 4 (14)
However,
LB: Lens back of the projection optical system (that is, air-converted back focus from the lens surface on the most reduction side to the image surface on the reduction side in the projection optical system),
m: number of lenses,
It is. The first projection optical system according to any one of claims 1 to 14, characterized in that movement to at least the one part of the zooming of the second optical system. 16. The projection optical system according to claim 15, wherein a part of the second optical system moves for zooming. An image display element having the image display surface, and the projection optical system according to any one of claims 1 to 16 , wherein an image displayed on the image display surface is enlarged and projected onto a screen surface. Projector featuring. The projector according to claim 17, wherein the image display surface and the screen surface are both flat.

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