JPH0727971A - Projection lenses of projection type display device - Google Patents

Abstract

PURPOSE:To provide a new type of lenses for projection in which a wide angle and high magnification/short projecting distance can be attained, and distortion aberration can be corrected satisfactorily, and a transmission type display body, etc., can be arranged easily. CONSTITUTION:These lenses include a common front group LF arranged on a screens S side and two rear groups LR1, LR2 formed in the same optical characteristic an combined with the front group LF via a color light synthesizing means PR, and are constituted so that light passing the rear groups LR1, LR2 can made incident on the front group LF after being synthesized by the color light synthesizing means PR, and assuming synthesized focal distant of a lens system comprised of the front group LF and the rear groups LR1, LR2 as (f), and the focal distance of each rear group as fR, condition 0.4<f/fR<0.65 can be satisfied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection lens for a projection type display device. INDUSTRIAL APPLICABILITY The present invention can be widely used for a color projection type display device using a transmissive display body such as a front type liquid crystal projector or a so-called rear type liquid crystal projection television.

[0002]

2. Description of the Related Art A light source emits light containing color components of three primary colors, and the light is color-separated into respective color component light of the three primary colors, and a corresponding transmissive display is provided by each color-separated color component light. A projection display device that displays color images on a screen by illuminating and synthesizing the color component lights that have passed through the transmissive displays and projecting them on the screen has been widely known as a liquid crystal projector or the like. There is.

The projection lens used in this type of projection display device generally has a high imaging magnification, and unless the contour of the image projected on the screen is deformed, distortion must be corrected with high precision. I won't. Further, there is also a strong demand for shortening the “projection distance” from the projection lens to the screen, and in order to realize this, the projection lens needs to have a wide angle.

Further, since a space for disposing a transmissive display body corresponding to each of the three primary colors and color light combining means is required on the light source side of the projection lens, a long back focus is required for the projection lens. It is said that

As described above, the projection lens is required to have a high imaging magnification, a wide angle of view, a good aberration characteristic, and a long back focus, and it has been extremely difficult to satisfy all of these requirements.

Further, in order to combine the images of the three primary colors to obtain a good color image on the screen, it is necessary that the lateral chromatic aberration of the projection lens is well corrected.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has a wide half angle of view of 35 degrees, a high magnification and a short projection distance, and good distortion. The objective of the present invention is to provide a novel projection lens that is corrected to the above and is easy to deploy a transmissive display and the like. Another object of the present invention is that the half angle of view is 35 degrees and the wide angle is wide, a high magnification and a short projection distance are possible, distortion is satisfactorily corrected,
It is intended to provide a novel projection lens in which a transmissive display body and the like can be easily arranged and chromatic aberration is well corrected.

[0008]

The projection lens according to the present invention is described as follows: "A light source emits light containing color components of three primary colors, and this light is color-separated into respective color component lights of the three primary colors. A projection display device that illuminates the corresponding transmissive display body with each of the component lights, synthesizes each color component light transmitted through each transmissive display body, and projects it on the screen to display a color image on the screen " Is a projection lens used in.

The projection lens according to claim 1 is composed of two rear groups and a front group commonly combined with these two rear groups. The "front group" is arranged on the screen side on which the color image is to be projected. The two "rear groups" are optically identical to each other and are combined with the front group via the color light combining means. That is, the lights that have passed through the two rear groups are combined by the color light combining means and are incident on the front group.

When the composite focal length of each lens system constituted by the front lens group and each rear lens group is f and the focal length of each rear lens group is f _R , these conditions (I) 0.4 <f / f _R <0.65 is satisfied.

The projection lens described in claim 2 has the following features in addition to the configuration of the projection lens described in claim 1. That is, each rear group has three or more positive lenses and one or more negative lenses, and the average Abbe number of the three or more positive lenses is ν _RP , the Abbe number of one or more negative lenses, or When the average is ν _RM , these satisfy the condition (II) ν _RP > 60 (III) ν _RM > 25.

In the projection type display device according to the above-mentioned claim 1 or 2, a dichroic mirror can be used as the "color light combining means" interposed between the front group and the rear group. The "dichroic prism" can be preferably used (claim 3).

[0013]

FIG. 1 shows an example of a "projection type display device" using the projection lens of the present invention. Code P is "light source"
White light lamps, reference numerals DM1, DM2, DM3 are dichroic mirrors, reference numerals M1, M2 are mirrors, reference numeral L
CD1, LCD2 and LCD3 indicate liquid crystal displays (so-called "liquid crystal light valves") as "transmissive display bodies". Further, reference numeral PR is a dichroic prism which is a “colored light combining means”, reference numeral LF is a “front group” of the projection lens,
Reference numerals LF1 and LF2 indicate two “rear groups”.

The white light emitted from the light source P has its infrared component removed by an infrared filter (not shown) and is separated into red, green and blue color component lights by the dichroic mirrors DM1 and DM3.

The "red component light" reflected by the dichroic mirror DM1 is reflected by the mirror M1 and transmitted through the liquid crystal display LCD1 which is a transmissive display for the red component and is a dichroic mirror DM which is a two-color light combining means.
Incident on 2.

The "green component light" of the light transmitted through the dichroic mirror DM1 is reflected by the dichroic mirror DM3, transmitted through the liquid crystal display LCD2 which is a transmissive display for the green component, and dichroic mirror D.
It is incident on M2.

The dichroic mirror DM2, which is a two-color light combining means, transmits red component light and reflects green component light. Therefore, the red component light and the blue component light are combined by the dichroic mirror DM2 and are incident on the dichroic prism PR which is the “color light combining means” via the rear group LR1.

The "blue component light" transmitted through the dichroic mirror DM3 is transmitted through the liquid crystal display LCD3 which is a transmissive display for the blue component, is then reflected by the mirror M2, and is transmitted to the dichroic prism PR via the rear group LR2. Incident.

The dichroic prism PR reflects red light and green light and transmits blue light. Therefore, the red, green, and blue color component lights are combined by the dichroic prism PR and enter the common front group LF.

As described above, the projection lens is composed of two rear groups LR1 and LR2 which have the front group LF in common and are independently combined with the front group LF. The front group LF and the rear group LR1 form a “projection lens for red component light and green component light”, and the liquid crystal displays LCD1, L
The image information displayed on the CD 2 is enlarged and projected on the screen S by red / green light. The front group LF and the rear group LR2 form a “projection lens for blue component light”, and the image information displayed on the liquid crystal display LCD3 is enlarged and projected on the screen S by blue light. Therefore, the screen S
A color image having each of the above image information as the three primary color components is synthetically formed on the upper side.

The condition (I) to be satisfied by the projection lens according to the first aspect is a condition for properly maintaining the distribution of the refractive powers of the front lens group LF and the rear lens groups LR1 and LR2. Since the refracting power is concentrated in the front group and the principal point of the entire projection lens system moves away from the position of the transmissive display, it is only possible to arrange a mirror or dichroic mirror between the transmissive display and each rear group. It becomes difficult to secure the back focus of.

If the upper limit of the condition (I) is exceeded, the rear lens group will have an excessive refractive power, and the aberration that will occur will also be excessive. Although it is possible to correct such an excessive aberration by increasing the number of lenses in the rear group, increasing the number of lenses in the rear group not only increases the cost but also increases the size of the projection display device itself. Also leads to From this point of view, the upper limit has an important meaning in order to prevent the number of constituent lenses of the rear group from increasing indefinitely.

Conditions (II) and (II) which are to be satisfied by the projection lens according to the second aspect together with the above condition (I).
I) is a condition for satisfactorily correcting chromatic aberration, and the condition (I
By satisfying I) and (III), it is possible to reduce the secondary spectrum of lateral chromatic aberration, and it is possible to realize a color display image with small registration and good color reproducibility.

As described above, in the present invention, since the "color light combining means" is provided between the common front group and the two rear groups, it is arranged in the space between each rear group and the light source. The number of other color light combining means can be reduced, and the back focus can be shortened.

[0025]

[Examples] Four specific examples will be given below. All of these four examples are examples of the projection lens according to claims 1 and 2, and the "dichroic prism" described with reference to FIG. 1 is used as the "color light combining means".
Of course, the two rear groups are identical to each other.

Throughout the entire embodiment, as illustrated in FIG.
Counting from the screen side (left side of the figure) toward the light source side (right side of the figure), the radius of curvature of the i-th surface (lens surface and surface of the dichroic prism PR) is r _i , counting from the screen side The surface distance on the optical axis between the i-th surface and the (i + 1) th surface is d _i .

The "refractive index for the e-line" and the Abbe number of the material of the j-th optical element (lens and dichroic prism) counted from the screen side are represented by n _j and ν _j , respectively.

F is the focal length of the entire system, F / No is the brightness,
ω represents a half angle of view (unit: degree). Further, the distance on the optical axis from the screen to the first lens surface of the front group is represented by L _SF , and the distance on the optical axis from the final lens surface of the rear group to the transmissive display (liquid crystal display) is represented by L _RD .

In the third embodiment, the "aspherical surface" is adopted as the lens surface in the rear lens group. As is well known, when the aspherical surface is aligned with the optical axis to take the X coordinate and is orthogonal to the optical axis to set the H coordinate, the curvature on the optical axis (the reciprocal of the radius of curvature) is c, the conic constant is K, When high-order aspherical coefficients are A and B, X = cH ² / {1 + √ [1- (1 + K) c ² H ² ]} + A
A curved surface obtained by rotating a curve represented by H ⁴ + B · H ⁶ around the optical axis, and the shape is specified by giving a conic constant and an aspherical coefficient. In addition, in the display of the aspherical surface coefficient, E and the number following it indicate a power. That is, for example, "E-9" means 1/10 ⁹ and this number is multiplied by the preceding number.

Example 1 f = 24.77, F / No = 3.02, ω = 34.5
_{5, L SF = 730, L} RD = 45.98 i r i d i j n j ν j 1 85.000 6.280 1 1.51872 64.2 2 -200.161 0.100 3 28.347 2.200 2 1.71615 53.9 4 13.981 7.600 5 -25.103 1.700 3 1.71615 53.9 6 49.198 2.147 7 -65.513 3.172 4 1.53431 48.8 8 -25.022 8.185 9 88.181 3.798 5 1.72341 50. 3 10 −39.900 3.100 11 ∞ (prism surface) 30.006 6 1.51872 64.2 12 ∞ (prism surface) 3.000 13 −38.563 1.200 7 1.812265 25.5 14 92.515 1.740 15 -163.500 4.035 8 1.51872 64.2 16 -28.502 0.100 17 420.916 4.660 9 1.48915 70.2 18 -3 6.130 0.100 19 89.965 5.000 10 1.48915 70.2 20 -49.941 Parameter value of conditional expression f / f _R = 0.57, ν _RP = 68.2, ν _RM = 25.5 FIG. 2 shows the lens configuration of the first embodiment.

Example 2 f = 24.77, F / No = 3.02, ω = 34.5
7, L _SF = 730, L _RD = 45.99 i r _i d _i j n _j ν _j 1 100.000 4.280 1 1.69980 55.5 2-750.087 0.100 3 35.971 2 .200 2 1.62032 63.4 4 16.949 7.600 5 -8.142 1.700 3 1.62032 63.4 6 23.431 3.647 7 -53.466 3.172 4 1.53431. 48.8 8 -42.176 6.685 9 56.491 3.798 5 1.72341 50.3 10 -78.016 3.100 11 ∞ (prism surface) 30.000 6 1.51872 64.2 12 ∞ (prism surface) 3.000 13 1287.642 3.000 7 1.66652 50.9 14 −39.942 1.200 8 1.76168 27.5 15 67.5 5 2.240 16 -348.217 3.750 9 1.51872 64.2 17 -38.485 0.100 18 234.521 4.330 10 1.48915 70.2 19 -50.771 0.100 20 78.906 5.000 11 1.48915 70.2 21 −79.264 Parameter values of conditional expression f / f _R = 0.61, ν _RP = 63.9, ν _RM = 27.5 FIG. 9 shows a lens configuration of Example 2.

Example 3 f = 24.13, F / No = 2.71, ω = 35.0
7, L _SF = 706, L _RD = 45.99 i r _i d _i j n _j ν _j 1 47.145 8.500 1 1.51872 64.2 2 194.526 0.100 3 34.549 1. 700 2 1.83930 37.3 4 20.960 5.600 5 49.225 1.700 3 1.71615 53.9 6 22.706 4.500 7 114.364 1.500 4 1.69980 55.5 8 27.750 14.000 9 -136.389 15.000 5 1.83930 37.3 10 -88.290 0.100 11 39.879 3.500 6 1.85649 32.3 12 223.342 2. 500 13 ∞ (prism surface) 27,000 7 1.652223 33.8 14 ∞ (prism surface) 1.000 15 50.868 7.500 8 1.4572 90.3 16 -23.060 0.100 17 -23.433 1.500 9 1.85649 32.3 18 74.111 2.100 19 330.583 5.000 10 1.62032 63.4 20 -33 0.067 0.100 21 110.090 4.880 11 1.62032 63.4 22 -49.941 Aspherical surface (21st surface: lens surface on the front group side of the rear lens group last lens) K = -9.9015, A = -2.6759E-6, B =
5.5802E-10 Conditional Parameter Values f / f _R = 0.49, ν _RP = 72.4, ν _RM = 32.3 FIG. 4 shows the lens configuration of the third embodiment.

Example 4 f = 24.14, F / No = 2.71, ω = 35.0
8, L _SF = 706, L _RD = 46 i r _i d _i j n _j ν _j 1 47.810 8.500 1 1.51872 64.2 2 195.253 0.100 3 31.139 1.700 2 1.839330 37.3 4 19.797 5.600 5 42.782 1.700 3 1.71615 53.9 6 21.239 4.500 7 87.859 1.500 4 1.69980 55.5 8 25 831 6.200 9 -227.550 25.000 5 1.83930 37.3 10 -175.053 0.100 11 42.012 2.000 6 1.85649 32.3 12 -1143.053 2.500 13 ∞ (prism surface) 25.000 7 1.65223 33.8 14 ∞ (prism surface) 1.000 15 95.398 7.500 8 1.45720 9 .3 16 -20.316 0.100 17 -20.828 1.500 9 1.85649 32.3 18 91.070 2.100 19 -122.954 3.900 10 1.62287 60.3 20 -32 .399 0.100 21 533.948 4.000 11 1.62032 63.4 22 -51.084 0.100 23 95.319 3.900 12 1.62032 63.4 24 -107.990 Parameter of conditional expression Value f / f _R = 0.52, ν _RP = 69.4, ν _RM = 32.3 FIG. 5 shows the lens configuration of the third embodiment.

FIG. 6 is a diagram of spherical aberration, astigmatism, and distortion relating to Example 1, and FIG. 7 is a diagram of coma. Further, a diagram of spherical aberration, astigmatism and distortion relating to Example 2 is shown in FIG. 8 and a diagram of coma aberration is shown in FIG.

FIG. 10 shows the spherical aberration / astigmatism / distortion aberration of the third embodiment, and FIG. 11 shows the coma aberration thereof.
Further, a diagram of spherical aberration, astigmatism and distortion relating to Example 4 is shown in FIG. 12, and a diagram of coma aberration is shown in FIG.

In these aberration diagrams, the solid line indicates the e line, the broken line indicates the g line, and the dotted line (fine broken line) indicates the C line. In the diagram of astigmatism, M indicates a meridional image plane and S indicates a sagittal image plane. These aberration diagrams are
Lateral magnification: on the reduction side at 1/30, that is,
The present invention relates to a reduced image when a screen is used as an object and the horizontal magnification is reduced to 1/30 by a projection lens. In each of the examples, various aberrations are corrected very well.

[0037]

As described above, according to the present invention, a novel projection lens can be provided. With this configuration, the projection lens can easily realize wide angle, high magnification, short projection distance, and high performance. In addition to the projection lens described in claim 2, chromatic aberration can be excellently corrected.

The transmissive display is not limited to the liquid crystal display, and the two-color light combining means provided between the rear group and the light source is not limited to the dichroic mirror.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an example of a projection type display device using a projection lens of the present invention.

FIG. 2 is a diagram showing a lens configuration according to example 1. FIG.

FIG. 3 is a diagram showing a lens configuration according to example 2.

FIG. 4 is a diagram showing a lens configuration according to example 3;

FIG. 5 is a diagram showing a lens configuration according to example 4.

FIG. 6 is a diagram showing spherical aberration, astigmatism, and distortion relating to Example 1;

FIG. 7 is a diagram showing coma aberration in Example 1.

FIG. 8 is a diagram showing spherical aberration, astigmatism, and distortion relating to Example 2;

FIG. 9 is a diagram showing coma aberration relating to Example 2;

FIG. 10 is a diagram showing spherical aberration, astigmatism, and distortion relating to Example 3;

FIG. 11 is a diagram showing coma aberration relating to Example 3;

FIG. 12 is a diagram showing spherical aberration, astigmatism, and distortion relating to Example 4;

FIG. 13 is a diagram showing coma aberration relating to Example 4;

[Explanation of symbols]

P light source LF front group LR1, LR2 rear group PR dichroic prism (color light combining means) DM1, DM2, DM3 dichroic mirror M1, M2 mirror LCD1, LCD2, LCD3 liquid crystal display (transmissive display)

Claims (3)

[Claims] 1. A light source that emits light containing color components of three primary colors, color-separates the light into color component light of the three primary colors, and a corresponding transmissive display is provided by each color-separated color component light. A projection lens used in a projection display device that illuminates and synthesizes each color component light transmitted through each transmissive display unit and projects a color image on the screen by projecting the color image on the screen. There is a common front group to be provided and two rear groups that are optically identical to each other and are combined with the front group via color light combining means, and the light passing through each rear group is combined by the color light combining means. When the combined focal length of each lens system constituted by the front group and each rear group is f and the focal length of each rear group is f _R , these conditions (I _{) 0.4 <f / f R <} 0 And satisfying the 65, projection lens of the projection type display device. 2. The projection lens of the projection type display device according to claim 1, wherein each rear group has three or more positive lenses and one or more negative lenses, and the three or more positive lenses. The average of the Abbe numbers of
_RP , a projection display device characterized by satisfying the condition (II) ν _RP > 60 (III) ν _RM > 25, where ν _RM is the Abbe number of one or more negative lenses or its average. Projection lens. 3. The projection type display device according to claim 1, wherein the color light combining means is a dichroic prism.