JP2001042211A - Projection lens and projection device using the lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection lens and a projection device using the lens capable of projecting the original picture of a projected picture displayed on a liquid crystal display element to the surface of a screen with high optical performance. SOLUTION: Picture information on plural color light beams based on plural display element is synthesized through a color synthesizing means and enlarged and projected by a projection lens PL to the surface of the screen S in this projection device. The lens PL is provided with a 1st lens group L1 having positive refractive power, a diaphragm, a means for folding an optical path, and a 2nd lens group L2 having negative refractive power in the above mentioned order from the display element side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection lens and a projection apparatus using the same, for example, a projection lens for enlarging and projecting an image displayed on a display device such as a liquid crystal display device at a fixed finite distance on a screen. A projection lens having good telecentric performance with respect to the color synthesizing prism on the liquid crystal display element side, and further having low distortion and excellent color characteristics, and particularly suitable for downsizing the rear projection set and the projection lens. It relates to the projection device used.

[0002]

2. Description of the Related Art Conventionally, a display device (projection device) that uses a plurality of display elements such as liquid crystal display elements, synthesizes images of respective color lights based on the display elements, and color-projects the images on a screen surface is often used. ing.

[0003] In recent years, as the definition of a projected image has been improved, the demand for downsizing of the entire apparatus has increased, and a small and high-performance projection lens has been desired.

Usually, in order to achieve both high brightness and high definition of a projected image, a white light from a light source is divided into three color lights of R, G, and B, and a display element for generating each color light is provided. Projection devices that combine color light images based on a plurality of display elements and project the images on a screen surface via a single projection lens are often used.

A so-called negative lead type projection lens (projection lens) in which a lens group having a negative refractive power precedes a screen side (projection surface side) as a projection lens can have a relatively wide angle of view and a focal length. It is easy to secure a long back focus as compared with the first embodiment, and is suitable mainly for a three-plate projection lens. However, on the other hand, there is a problem that the total length of the optical system is increased.

[0006] At present, consumer-spec televisions have C
There are two types, an RT system and a rear projection system. Among them, the CRT method has troublesome problems such as an increase in size and weight of the device. In contrast, rear-projection televisions are advantageous for market needs such as thinner and lighter ones. However, as the trend toward further downsizing of the device is increased, the angle of view of the projection lens and the depth (thickness direction) are increased. There is a need to make good use of space (to design thinner).

According to JP-A-9-218379,
By providing an optical path bending means composed of a prism in a projection system using a wide angle lens of a retrofocus type, the rear projection set is made compact in the depth direction.

[0008]

Problems to be Solved by the Invention Three color light images (display images) based on three liquid crystal display elements for red, green and blue
When combining with a color composition system and projecting it on a screen in an enlarged manner, it is necessary to satisfy, for example, the following conditions as a projection lens in order to reduce the size of the entire device while maintaining good optical characteristics. It is becoming.

(A-1) To eliminate the influence of the light distribution characteristics of the liquid crystal display element or the angle dependence of the color synthesizing dichroic film when synthesizing a plurality of color lights, and to achieve good matching with the illumination system. A so-called telecentric optical system in which the apparent pupil position (the pupil on the liquid crystal display element side) is at infinity with respect to the color combining prism in order to sufficiently secure the illuminance around the screen.

(A-2) Since a retrofocus type projection lens has a pincushion type distortion on the screen side, the distortion is made inconspicuous. Particularly in the case of a rear projection television, the distortion is at most an absolute value of 0.5. %.

[0011] In response to the above requirements, Japanese Patent Laid-Open No. 9-21 / 1990
In JP 8739, a condenser lens is inserted immediately after the liquid crystal display element. For this reason, if telecentric illumination is performed on the liquid crystal display element with respect to the color combining prism inside the projection system, the apparent pupil position of the projection system, especially the color combining prism, is replaced by a finite distance, It is hard to say that the configuration is advantageous for color unevenness in the color synthesis section on the screen.

Further, since the condenser lens is required in accordance with the number of color panels (three), the structure tends to be complicated.

On the other hand, in a projection apparatus in which an optical path bending means for reflecting a light beam at a large angle of 90 ° or more is arranged in the optical system, in order to secure a space for arranging the optical path bending means, each lens group of the optical system is required. It is necessary to set the refractive power appropriately. If the refractive power arrangement is not appropriate, it becomes difficult to obtain good optical performance while having a predetermined projection angle of view.

According to the present invention, when a plurality of color light images based on a plurality of display elements are combined by a color combining means and projected on a screen surface by a projection lens, the configuration of the projection lens is appropriately set. While maintaining the optical performance of the image on the screen while miniaturizing the entire device,
It is an object of the present invention to provide a projection lens capable of projecting and a projection device using the same.

[0015]

According to a first aspect of the present invention, there is provided a projection apparatus in which image information of a plurality of color lights based on a plurality of display elements is synthesized via a color synthesizing means, and is enlarged and projected on a screen surface by a projection lens. A first lens group having a positive refractive power in order from the display element side,
It is characterized by having a stop, means for bending the optical path, and a second lens group having a negative refractive power.

According to a second aspect of the present invention, in the first aspect of the present invention, the projection lens is substantially telecentric on the display element side, and the light beam from the display element is not subjected to an optical action having a refracting power to perform the color synthesis. It is characterized by being incident on the means.

According to a third aspect of the present invention, in the first or second aspect, the means for bending the optical path is a prism.

According to a fourth aspect of the present invention, in the first or second aspect, the means for bending the optical path is a mirror.

The invention of claim 5 is the invention of claim 1, 2, 3, or 4.
In the invention, the focal length of the second lens group is f2,
When the focal length of the entire system is f, 2.0 <| f2 / f | <4.0 is satisfied.

According to a sixth aspect of the present invention, in the invention of any one of the first to fifth aspects, the distance from the display element to the reflection surface of the means for bending the optical path is lref, and the lens closest to the screen from the liquid crystal display element. Distance to the face vertex position
When ltt, 0.50 <lref / ltt <0.75 is satisfied.

According to a seventh aspect of the present invention, in the invention of any one of the first to sixth aspects, the stop is disposed near the optical path bending means, and a main plane position on the screen side with respect to the first lens group from the stop. 0.75 <o1 / f1 <1.0, where o1 is the distance to the lens and f1 is the focal length of the first lens group.

According to an eighth aspect of the present invention, in the first aspect of the present invention, the second lens group includes at least two negative meniscus lenses each having a convex surface directed in order from the screen side. It is characterized in that the lens surface has a convex positive lens.

According to a ninth aspect of the present invention, in any one of the first to eighth aspects of the present invention, the second lens group includes at least one aspherical lens.

According to a tenth aspect, in the ninth aspect, the aspherical lens included in the second lens group is made of plastic.

According to an eleventh aspect of the present invention, in any one of the first to tenth aspects, the first lens group includes at least one aspherical lens.

According to a twelfth aspect of the present invention, in the eleventh aspect, the aspherical lens included in the first lens group is made of plastic.

According to a thirteenth aspect of the present invention, in the first aspect of the present invention, the first lens group includes a cemented lens of a positive lens and a negative lens having a positive lens disposed on the display element side. It is characterized by including at least two sets.

According to a fourteenth aspect of the present invention, in any one of the first to thirteenth aspects, the focal length is made variable by changing the distance between the lens groups in the first lens group. I have.

According to a fifteenth aspect of the present invention, in any one of the first to fourteenth aspects, floating adjustment is performed by changing a lens interval in the second lens group.

According to a sixteenth aspect of the present invention, in the projection lens for projecting a projection image on a predetermined surface, the projection lens is telecentric on the projection image side and has a positive refractive power in order from the projection image side. A first lens unit, a stop, a unit for bending an optical path, and a second lens unit having a negative refractive power, wherein the focal length of the i-th lens unit is f i, the focal length of the entire system is f, and the first lens unit is from the stop. Where 2.0 <f2 / f <4.0 0.75 <o1 / f1 <1.0 when the distance to the main plane position on the predetermined surface side is represented by o1.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view of a main part of a projection apparatus using a projection lens (projection lens) according to a first embodiment of the present invention. In FIG. 1, PL is a projection lens. 1 is a liquid crystal display element (liquid crystal display) L
Color synthesis prism XPR, first lens unit having a positive refractive power, L1, stop ST, optical path bending prism P in order from the CD side
R and a second lens unit L2 having a negative refractive power. S is a screen. ASP is an aspherical surface provided on the lens surface.

There are three liquid crystal display devices (LCD) for displaying three images for red, green and blue, but one is shown in FIG. 1 for simplicity.

The light beams from the images of the three liquid crystal display devices are combined into one by the color combining prism XPR, and the first lens unit L
1. The light is projected onto the screen S via the prism PR, and the second lens unit L2.

The color synthesizing prism XPR comprises a known cross dichroic prism in which four pieces of right-angled triangular prisms are bonded together.

In this embodiment, the color synthesizing prism XP
The position of the stop ST of the projection lens PL as viewed from R is set at substantially infinity, that is, the position of the pupil on the liquid crystal display element side is telecentric at infinity. The angle of the off-axis principal ray in the prism XPR is within ± 1 °, so that the color in the color synthesis cross-sectional direction on the screen S in the color synthesis prism XPR (the horizontal direction of the screen in the present embodiment). This prevents unevenness.

In the projection device of this embodiment, the liquid crystal display element L
The CD is illuminated with a light beam from an illumination system (not shown). In the projection lens PL, the dichroic film of the color combining prism (XPR) does not give refracting power to the light from the illumination system illuminating the liquid crystal display element LCD, that is, the off-axis principal ray is parallel to the lens optical axis La. Is transmitted.

Thus, the optical transmission characteristics are not influenced by the variation of the angle of incidence of various off-axis lights on the dichroic film, and the optical characteristics symmetric with respect to the color synthesis section are maintained.

After passing through the color combining prism XPR, the projection lens PL becomes a first lens unit L having a positive refractive power.
A so-called retrofocus type lens system is adopted when viewed from the screen S side, including a lens unit 1 and a unit PR for bending the optical path and a second lens unit L2 having a negative refractive power. As a result, a sufficient and sufficient back focus is provided for the arrangement of the color combining prism XPR.

The first lens unit L1 of the projection lens PL
As for the refractive power arrangement inside, a long back focus of about three times the focal length ratio is secured by shifting the main plane to the liquid crystal display LCD side by giving a positive refractive power to the liquid crystal display LCD side. ing.

Further, a prism PR disposed between the first and second lens units L1 and L2 provides a liquid crystal display device LCD.
The light path is launched upward by about 66 ° with respect to the short side cross section of the liquid crystal display. After projecting this projector, the image of the liquid crystal display LCD is formed on the screen S via a folding mirror (not shown) provided in the system. It is designed to image.

This saves space especially in the depth direction of the apparatus. The reflection surface of the prism PR is treated with a high-band reflection mirror, and the light entrance / exit surfaces are treated with a multilayer coat.

In addition, it is preferable to perform a mask process on a region outside the effective diameter of the projection optical system on the reflection surface of the prism PR in order to cut ghosts and flares.

Regarding the second lens unit L2, a small refractive power arrangement is realized by concentrating negative refractive power on the screen S side and shifting the main plane from the front lens to the screen S side. In this way, mainly off-axis aberrations such as barrel distortion and magnification chromatic aberration peculiar to the retrofocus lens are favorably corrected, and at the same time, a bright optical system having a peripheral illuminance ratio of 70% while having a super wide angle of 46 ° half angle of view is provided. While realizing, it contributes to keeping the diameter of the front lens small.

Further, two meniscus-shaped negative lenses are arranged on the most screen S side in the second lens unit L2 having a large refractive power for obtaining a back focus, and an aspheric surface is adopted for these negative lenses. I have. This suppresses the generation of the pincushion-type distortion particularly on the screen S side.

When used as a projection lens, it is desirable to apply a multilayer coating to the entire lens surface in order to increase the brightness of the light source.

The numerical values of the rear projection lens (projection lens) of the present embodiment in numerical examples are expressed in units of mm, and the lens is focused on 0.5 m (when the projection distance is 0. 0).
5m) is shown in FIG.

The projection apparatus aimed at by the present invention has been achieved by the above configuration, but it is more preferable to satisfy at least one of the following conditions.

(A-1) Assuming that the focal length of the second lens group is f2 and the focal length of the entire system is f, 2.0 <| f2 / f | <4.0 (1) is satisfied. It is to be.

When the value exceeds the upper limit of conditional expression (1), the refractive power of the second lens unit having a negative refractive power becomes small, so that the arrangement space for the color combining prism becomes small, or the lens diameter on the screen side becomes large. Such adverse effects occur.

Conversely, if the lower limit of conditional expression (1) is exceeded, the second condition
The negative refracting power of the lens group becomes strong, and not only is it difficult to correct distortion and chromatic aberration of magnification, but also the back focus becomes too long, which wastes space and is not preferable.

(A-2) When the distance from the liquid crystal display element to the reflection surface of the means for bending the optical path is lref, and the distance from the liquid crystal display element to the vertex position of the lens surface closest to the screen is ltt, 0.50 <Lref / ltt <0.75 ‥‥‥ (2).

If the lower limit of conditional expression (2) is exceeded, the diameter of the lens on the screen side will increase, and if the upper limit of conditional expression (2) is exceeded, on the other hand, the refractive power of the positive lens group on the liquid crystal display element side will increase. And the refractive power of the second lens group and the positive lens group in the vicinity of the means for bending the optical path increase, which makes it difficult to correct pincushion distortion on the screen side, which is not preferable.

(A-3) In this embodiment, not only a prism but also a mirror may be employed as the optical path bending means. When a mirror is used, the optical path is shortened by an amount corresponding to the air in the medium as compared with the prism.

Then, the optical path is set to 90 ° or more with respect to the short side cross section of the liquid crystal display element (specifically, 114 °).
In order to respond to the need to bend at (°), it is necessary to break down the optimum refractive power arrangement for securing a space between the first and second lens groups.

Therefore, in the present invention, attention is paid to the fact that a relatively large space can be taken in the width direction of the set (horizontal direction of the screen) for the rear projection set, and as shown in FIG. The light path is developed by Steering-Mirror (MR) in the direction of the short side cross section (the direction of the depth arrow of the set) with respect to the liquid crystal display element (Examples 2 and 3). In this system, a bending angle of Steering-Mirror of about 90 ° is sufficient, and the arrangement of the refractive power does not need to be destroyed in order to secure a space necessary for bending the optical path. Further, light loss due to absorption inside the material can be prevented as compared with the example in which the optical path is bent by the prism.

(A-4) The stop is preferably arranged near the optical path bending means. According to this, it is possible to reduce the size of the prisms and mirrors that are the optical path bending means, and especially when configured with prisms, not only minimize light loss due to internal absorption, but also reduce weight and cost. Is possible.

(A-5) The stop is arranged near the optical path bending means, and the distance from the stop to the main plane position on the screen side with respect to the first lens group is o1, and the focal length of the first lens group is When f1 is set, 0.75 <o1 / f1 <1.0 (3) is satisfied.

This is a description of the telecentric performance on the liquid crystal display element side, that is, on the color combining prism surface. If the lower limit of conditional expression (3) is exceeded, the refracting power of the first lens group becomes too large, making it difficult to correct off-axis aberrations, as well as poor matching with the illumination system, and especially illuminance around the screen. It is not preferable that the ratio is lowered.

Conversely, exceeding the upper limit value is advantageous for correcting off-axis aberrations, but reduces the illuminance around the screen as described above.

(B-6) The second lens group includes at least two negative meniscus lenses having convex surfaces facing the screen in order from the screen side, and positive lenses having both lens surfaces convex. It is that you are.

In the case of an ultra wide angle lens having a long back focus, the second lens group gently bends the light beam and guides it to the screen in order to properly correct off-axis aberrations.

Further, by configuring the second lens unit in this manner, the position of the main plane is shifted to the screen side, and the configuration of the system is made compact.

(A-7) The second lens group includes at least one aspheric lens.

This facilitates correction of pincushion distortion on the screen side.

(A-8) The aspheric lens included in the second lens group is made of plastic.

When an aspherical lens is used for the second lens group, it is preferable that the material of the aspherical lens is, for example, pmma, which has relatively excellent polarization characteristics, that is, optical distortion characteristics.

(A-9) The first lens group includes at least one aspheric lens.

Since the positive lens of the first lens group on the liquid crystal display element side has the same function as the negative lens of the second lens group, it is preferable to employ an aspheric lens. According to this, it becomes easy to satisfactorily correct the pincushion distortion on the screen side.

(A-10) The aspheric lens included in the first lens group is made of plastic.

In particular, with respect to this material, acrylic pmma or the like, which has relatively excellent polarization characteristics, that is, optical distortion characteristics, is preferable.

(A-11) The first lens group includes at least two sets of a cemented lens of a positive lens and a negative lens, each having a positive lens disposed on the liquid crystal display element side.

With this arrangement, the principal plane position of the first lens group is shifted to the liquid crystal display element to secure a long back focus.
In addition, the bonding is effective for correcting the chromatic aberration of magnification.

(B-12) The distance between the lens units in the first lens unit is made variable, so that the focal length is made variable.

In view of the needs of the rear projection apparatus as in the present invention, it is preferable to provide a magnification adjusting mechanism for absorbing manufacturing error variations of various lenses. At this time, it is preferable from the viewpoint of aberration correction to make the focal length variable by making the lens unit interval in the first lens unit variable.

(A-13) Floating adjustment is performed by making the lens interval in the second lens group variable.

A focus mechanism is also required for smooth conversion to various screen sizes. In this case, in order to correct the image plane tilt peculiar to the wide-angle lens, the lens interval in the second lens group is corrected. It is good to make Floating adjustment by making variable.

FIG. 2 is a schematic view of a main part of a second embodiment of a projection apparatus using a projection lens according to the present invention.

The projection device shown in FIG. 2 has a color synthesis prism XPR, a first lens unit L1 having a positive refractive power, an optical path bending mirror MR, and a second lens unit L2 having a negative refractive power in order from the liquid crystal display device LCD side. It consists of The mirror MR functions as reflection and stop.

In the present embodiment, unlike the first embodiment, one aspheric lens (aspheric ASP) is arranged in each of the first lens unit L1 and the second lens unit L2.

The first embodiment is used as an optical path bending means.
Unlike this, a mirror (Steering-Mirror) MR is adopted.

In this embodiment, paying attention to the fact that a relatively large space can be taken in the lateral width direction of the rear projection set, light from the set lateral width (arrow) direction is applied by the Steering-Mirror MR as shown in FIG. The optical path is folded and developed in the direction of the short side section (arrow) (90 ° direction) of the liquid crystal display device LCD. This allows Stee
A bending angle of about 90 degrees is enough for the ring-Mirror MR, which not only makes it possible to prevent the arrangement of the refractive power from being disrupted in order to secure the space required for bending the optical path.
As compared with the example where the optical path is bent by the prism, it is possible to prevent the loss due to the absorption inside the material.

The other parts are the same as those of the first embodiment, so that the detailed description will be omitted.

FIG. 5 is an aberration diagram when the rear projection lens (projection lens) of this embodiment is focused on 0.5 m.

FIG. 3 is a schematic view of a main part of a third embodiment of a projection apparatus using a projection lens according to the present invention. 3 is a color synthesis prism XPR in order from the liquid crystal display device LCD side.
First lens unit L1 having positive refractive power, optical path bending mirror M
R and a second lens unit L2 having a negative refractive power.

In the present embodiment, unlike the second embodiment, two aspheric lenses (aspheric ASP) are provided in the second lens unit L2.
Are arranged one by one.

Further, unlike the first embodiment, a mirror (Steering-Mirror) MR is employed as the optical path bending means.

In this embodiment, paying attention to the fact that a relatively large space can be taken in the width direction of the rear projection set, as shown in FIG.
The light from the direction is bent and developed by the Steering-Mirror MR in the short side direction (arrow) direction (90 degree direction) with respect to the liquid crystal display device LCD.

Thus, the bending angle of the Steering-Mirror MR is about 90 ° is sufficient, and it is possible not only to prevent the arrangement of the refractive power from being disrupted in order to secure the space required for bending the optical path, but also to reduce the angle of the prism. Thus, the loss due to absorption inside the material can be prevented as compared with the example in which the optical path is bent.

The other points are the same as those of the second embodiment, so that the detailed description will be omitted.

FIG. 6 is an aberration diagram when the rear projection lens (projection lens) of the present embodiment is focused on 0.5 m.

Next, numerical examples of the present invention will be described. In the numerical examples, Ri is the i-th radius of curvature in the order from the screen side, Di is the thickness or air space of the i-th optical member in the order from the screen side, and Ni and νi are the i-th in the order from the screen side. Are the refractive index and the Abbe number of the material of the optical member for d-line.

The last two surfaces in the numerical examples show an optical filter, a face plate and the like.

The aspherical shape has an X axis in the optical axis direction, an H axis in a direction perpendicular to the optical axis, a positive traveling direction of light, R represents a paraxial radius of curvature, and A, B, C, D, and E represent aspherical shapes. Assuming spherical coefficients,

[0094]

(Equation 1)

This is expressed by the following equation.

Table 1 shows the relationship between the above-mentioned conditional expressions and the numerical examples. Numerical Example 1 fno. 1: 2.4 2ω = 46 ° × 2 R 1 = 56.735 D 1 = 4.20 N 1 = 1.49376 ν 1 = 57.1 * R 2 = 34.761 D 2 = 11.03 R 3 = 48.612 D 3 = 3.60 N 2 = 1.49376 ν 2 = 57.1 * R 4 = 33.416 D 4 = 20.16 R 5 = 101.142 D 5 = 3.50 N 3 = 1.65355 ν 3 = 52.0 R 6 = 26.619 D 6 = 9.71 R 7 = 1201.789 D 7 = 3.10 N 4 = 1.66041 ν 4 = 51.0 R 8 = 45.000 D 8 = 5.86 R 9 = 96.151 D 9 = 5.69 N 5 = 1.83932 ν 5 = 37.2 R10 = -143.905 D10 = 3.65 R11 = ∞ D11 = 42.50 N 6 = 1.51825 ν 6 = 64.1 R12 = ∞ ( Aperture) D12 = 12.18 R13 = -250.900 D13 = 2.50 N 7 = 1.83932 ν 7 = 37.2 R14 = 25.357 D14 = 10.23 N 8 = 1.81264 ν 8 = 25.4 R15 = -108.581 D15 = 0.10 R16 = 43.723 D16 = 9.32 N 9 = 1.48915 ν 9 = 70.2 R17 = -49.690 D17 = 4.10 R18 = -49.244 D18 = 2.60 N10 = 1.80619 ν10 = 27.7 R19 = 45.000 D19 = 8.77 N11 = 1.48915 ν11 = 70.2 R20 = -58.143 D20 = 0.20 R21 = -3521.585 D21 = 3.00 N12 = 1.83932 ν12 = 37.2 R22 = 50.000 D22 = 8.75 N13 = 1.48915 ν13 = 70.2 R23 = -72.544 D23 = 0.20 R24 = 95.678 D24 = 6.08 N14 = 1.48915 ν14 = 70.2 R25 = -163.332 D25 = 0.20 R26 = 60.462 D26 = 6.62 N15 = 1.48915 ν15 = 70.2 R27 = 1000.000 D27 = 14.50 R28 = ∞ D28 = 50.00 N16 = 1.51825 ν16 = 64.1 R29 = ∞ Aspheric coefficient 2 planes R 3.47608D + 01 K -4.21977D-1 B 1.80509D-06 C -3.31417D-09 D 1.74821D-12 E- 7.16448D-16 Four sides R 3.34163D + 01 K -1.73657D-1 B-3.70371D-06 C 7.63396D-09 D -8.18170D-12 E 3.68298D-15 Numerical example 2 fno. 1: 2.4 2ω = 46 ° × 2 R 1 = 56.126 D 1 = 4.20 N 1 = 1.49376 ν 1 = 57.1 * R 2 = 32.986 D 2 = 12.02 R 3 = 51.810 D 3 = 4.00 N 2 = 1.66107 ν 2 = 51.0 R 4 = 36.042 D 4 = 11.41 R 5 = 62.817 D 5 = 3.50 N 3 = 1.66107 ν 3 = 51.0 R 6 = 29.444 D 6 = 12.84 R 7 = -116.031 D 7 = 3.10 N 4 = 1.66108 ν 4 = 50.9 R 8 = 51.667 D 8 = 13.86 R 9 = 141.097 D 9 = 8.01 N 5 = 1.83932 ν 5 = 37.2 R10 = -100.161 D10 = 37.22 R11 = ∞ (aperture) D11 = 17.03 R12 = 93.714 D12 = 2.50 N 6 = 1.83932 ν 6 = 37.2 R13 = 25.279 D13 = 7.94 N 7 = 1.81264 ν 7 = 25.4 R14 = 159.642 D14 = 0.10 R15 = 37.960 D15 = 8.23 N 8 = 1.48915 ν 8 = 70.2 R16 = -59.594 D16 = 4.10 R17 = -50.000 D17 = 2.60 N 9 = 1.80771 ν 9 = 28.9 R18 = 45.000 D18 = 9.71 N10 = 1.48915 ν10 = 70.2 R19 = -51.417 D19 = 0.20 R20 = -277.052 D20 = 3.00 N11 = 1.83932 ν11 = 37.2 R21 = 50.000 D21 = 8.15 N12 = 1.48915 ν12 = 70.2 R22 = -85.013 D22 = 0.20 R23 = 54.945 D23 = 9.77 N13 = 1.48915 ν13 = 70.2 R24 = -269.477 D24 = 0.20 * R25 = 72.603 D25 = 6.22 N14 = 1.49376 ν14 = 57.1 R26 = 2757.961 D26 = 10.00 R27 = ∞ D27 = 45.00 N15 = 1.51825 ν15 = 64.1 R28 = ∞ Aspheric coefficient 2 plane R 3.29861D + 01 K -4.58369D-1 B 2.05598D-07 C -2.24051D-09 D 1.28789D-12 E -6.88048D-16 25 plane R 7.26028D + 01 K -2.82554D + 00 B-1.26556D-06 C -1.21731D-09 D 3.56772D-13 E -1.11789D-15 Numerical example 3 fno. 1: 2.4 2ω = 46 ° × 2 R 1 = 56.408 D 1 = 4.20 N 1 = 1.49376 ν 1 = 57.1 * R 2 = 34.719 D 2 = 11.34 R 3 = 49.150 D 3 = 3.60 N 2 = 1.49376 ν 2 = 57.1 * R 4 = 33.405 D 4 = 18.33 R 5 = 117.783 D 5 = 3.50 N 3 = 1.61951 ν 3 = 50.7 R 6 = 28.152 D 6 = 10.30 R 7 = 1651.255 D 7 = 3.10 N 4 = 1.66108 ν 4 = 50.9 R 8 = 45.000 D 8 = 11.81 R 9 = 94.883 D 9 = 7.68 N 5 = 1.83932 ν 5 = 37.2 R10 = -140.017 D10 = 32.34 R11 = 絞 り (aperture) D11 = 14.65 R12 = -569.806 D12 = 2.50 N 6 = 1.83932 ν 6 = 37.2 R13 = 27.104 D13 = 8.19 N 7 = 1.81264 ν 7 = 25.4 R14 = -154.044 D14 = 0.10 R15 = 42.097 D15 = 9.22 N 8 = 1.48915 ν 8 = 70.2 R16 = -54.789 D16 = 4.10 R17 = -50.013 D17 = 2.60 N 9 = 1.81951 ν 9 = 27.8 R18 = 45.000 D18 = 8.76 N10 = 1.48915 ν10 = 70.2 R19 = -56.842 D19 = 0.20 R20 = -1194.588 D20 = 3.00 N11 = 1.83932 ν11 = 37.2 R21 = 50.000 D21 = 8.87 N12 = 1.48915 ν12 = 70.2 R22 = -66.895 D22 = 0.20 R23 = 101.029 D23 = 5.60 N13 = 1.48915 ν13 = 70.2 R24 = -208.991 D24 = 0.20 R25 = 57.185 D25 = 7.83 N14 = 1.48915 ν14 = 70.2 R26 = 1000.000 D26 = 10.00 R27 = ∞ D27 = 50.00 N15 = 1.51825 ν 15 = 64.1 R28 = ∞ Aspheric coefficient 2 plane R 3.47188D + 01 K -4.31944D-1 B 1.79158D-06 C -3.28606D-09 D 1.75818D-12 E -7.10970D-16 4 plane R 3.34045D + 01 K -1.67858D-01 B-3.68582D-06 C 7.73398D-09 D -8.41642D-12 E 3.72052D-15

[0097]

[Table 1]

[0098]

According to the present invention, when a plurality of color light images based on a plurality of display elements are combined by a color combining means and projected onto a screen surface by a projection lens, the configuration of the projection lens is appropriately adjusted. By setting, a projection lens capable of projecting the image on a screen while maintaining good optical performance while reducing the size of the entire apparatus, and a projection apparatus using the same can be achieved.

In addition, according to the present invention, a three-plate super wide-angle rear projection lens capable of significantly reducing the size in the depth direction of the set while realizing low distortion, excellent color characteristics and peripheral illumination ratio is provided. Can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic view of a main part of a projection device according to a first embodiment of the invention.

FIG. 2 is a schematic view of a main part of a projection device according to a second embodiment of the present invention.

FIG. 3 is a schematic view of a main part of a projection device according to a third embodiment of the invention.

FIG. 4 shows the numerical value of numerical example 1 of the projection lens of the present invention as m.
Diagram of spherical aberration, field curvature, distortion, and lateral chromatic aberration at a projection distance of 0.5 m when expressed in m units

FIG. 5 is a diagram showing a numerical value m of the numerical example 2 of the projection lens of the present invention.
Diagram of spherical aberration, field curvature, distortion, and lateral chromatic aberration at a projection distance of 0.5 m when expressed in m units

FIG. 6 shows a numerical value of the numerical example 3 of the projection lens of the present invention as m.
Diagram of spherical aberration, field curvature, distortion, and lateral chromatic aberration at a projection distance of 0.5 m when expressed in m units

FIG. 7 is a schematic diagram of a main part of a projection device according to the present invention.

[Explanation of symbols]

 PL Projection lens L1 First lens group L2 Second lens group XPR Color combining prism ASP Aspheric surface S screen LCD Liquid crystal display (image plane) MR Steering-Mirror ST Stop ΔS Sagittal image plane ΔM Meridional image plane

Claims (16)

[Claims] 1. A projection apparatus for combining image information of a plurality of color lights based on a plurality of display elements via a color combining means and enlarging and projecting the image information on a screen surface by a projection lens, wherein the projection lens is a display element. A projection device comprising: a first lens group having a positive refractive power, a stop, means for bending an optical path, and a second lens group having a negative refractive power in order from the side. 2. The projector according to claim 1, wherein the projection lens is substantially telecentric on the display element side, and a light beam from the display element is incident on the color synthesizing unit without receiving an optical action having a refractive power. The projection device according to claim 1. 3. The projection device according to claim 1, wherein the means for bending the optical path is a prism. 4. The projection device according to claim 1, wherein the means for bending the optical path is a mirror. 5. The lens system according to claim 1, wherein 2.0 <| f2 / f | <4.0 when the focal length of the second lens group is f2 and the focal length of the entire system is f. , 2, 3 or 4 projection devices. 6. When the distance from the display element to the reflection surface of the means for bending the optical path is 1 ref, and the distance from the liquid crystal display element to the vertex position of the lens surface closest to the screen is ltt: 0.50 <lref / ltt The projection device according to any one of claims 1 to 5, wherein <0.75 is satisfied. 7. The stop is arranged in the vicinity of the optical path bending means, and a distance from the stop to a main plane position on the screen side with respect to the first lens group is defined as o1, and a focal length of the first lens group is defined as f1. 7. The projection device according to claim 1, wherein 0.75 <o1 / f1 <1.0 is satisfied. 8. The second lens group includes at least two negative meniscus lenses having convex surfaces directed in order from the screen side, and both positive lens surfaces having convex lens surfaces. Item 8. The projection device according to any one of Items 1 to 7. 9. The projection device according to claim 1, wherein the second lens group includes at least one aspherical lens. 10. The aspherical lens included in the second lens group is made of plastic.
Projection equipment. 11. The apparatus according to claim 1, wherein the first lens group includes at least one aspherical lens.
The projection device according to any one of the above. 12. The aspherical lens included in the first lens group is made of plastic.
1. Projection device. 13. The apparatus according to claim 1, wherein the first lens group includes at least two sets of a cemented lens of a positive lens and a negative lens, each having a positive lens disposed on the display element side.
13. The projection device according to any one of items 1 to 12. 14. The projection apparatus according to claim 1, wherein a focal length is variable by changing a distance between lens groups in the first lens group. 15. The projection apparatus according to claim 1, wherein a floating interval is adjusted by changing a lens interval in the second lens group. 16. A projection lens for projecting a projection image on a predetermined surface, wherein the projection lens is telecentric on the projection image side, and the first lens group, the stop, and the optical path having a positive refractive power are sequentially arranged from the projection image side. Means for bending, and a second lens group having a negative refractive power, wherein the focal length of the i-th lens group is fi, the focal length of the entire system is f, and the principal plane of the first lens group from the stop to the predetermined surface side A projection lens characterized by satisfying 2.0 <f2 / f <4.0 0.75 <o1 / f1 <1.0 when a distance to a position is o1.