JPH06214155A - Condenser lens, polarizing element, light source device and projection type display device - Google Patents

Abstract

PURPOSE:To provide a large aperture condenser lens, and a polarizing element which realize the high brightness of a liquid crystal projector and which are for illumination; and a light source device, and a projection type display device using them. CONSTITUTION:The condenser lens 131 is constituted of a both-side aspherical single lens whose first surface S1 is a convex face and whose second surface S2 is a concave surface on the peripheral part. The light source device is constituted of the condenser lens 131, a discharging lamp 120, and a reflection mirror 130; the center of the curvature of the reflection mirror 130 and a focal point position on the second surface side of the condenser lens 131 are on a nearly common point, and the light emitting center of the discharging lamp 120 is set on the common point.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a large-diameter condenser lens capable of converging light emitted from a light source with high efficiency, a high-efficiency light source device using the condenser lens, a projection type display device using the light source device, and a polarization direction. Relates to a polarizing element or the like that converts indefinite natural light into partial polarized light in which the polarized light is large only in one direction.

[0002]

2. Description of the Related Art A projection type display device using a liquid crystal panel will be described with reference to FIG. 50 as an example of the prior art which requires a highly efficient light source device. Figure
Reference numeral 50 is the device disclosed in, for example, Japanese Patent Laid-Open No. 1-2687. In the figure, reference numeral 1 denotes a light source device, which includes a lamp 120, a reflecting mirror 130, and a condenser lens 131. 2 is an illumination luminous flux emitted from the light source device 1, 14B, 14R
Is a dichroic mirror, 11a, 11b, 11c and 11d are mirrors, 3R, 3G and 3B are liquid crystal panels, 15 is a dichroic prism, 4 is a projection lens, and 5 is a screen.

Next, the operation will be described. As the lamp 120 used in the light source device 1, for example, a white light source such as a metal halide lamp, a xenon lamp or a halogen lamp is used. By arranging the lamp 120 at the focal position of the condenser lens 131, a parallel illumination light flux 2 can be obtained. The reflecting surface of the reflecting mirror 130 is typically a spherical surface, and the center of curvature of the reflecting mirror 130 is set near the focal position of the condenser lens 131 (that is, the position of the lamp 120) so that the condenser lens 131 emits light. It is known that the power of the light beam 2 is about twice as high as that in the case without the reflecting mirror 130.

The illumination luminous flux 2 is decomposed into three primary colors of red, green and blue by a dichroic mirror 14B which reflects blue light and transmits green / red light and a dichroic mirror 14R which reflects red light and transmits green / blue light. To be done. Red light mirror
The liquid crystal panel 3R is bent by 11b and 11c and is irradiated onto the liquid crystal panel 3R, and the blue light is bent by mirrors 11a and 11d and is irradiated onto the liquid crystal panel 3B. Further, the green light is directly applied to the liquid crystal panel 3G. LCD panel 3R, 3G, 3B red, green,
An image corresponding to each of the blue primary colors is displayed, but the drive circuit for displaying the image is not shown. The light beam modulated by the image formed on the liquid crystal panel is combined again into a single light beam by a known dichroic prism 15 that selectively reflects red and blue light and selectively transmits green light, and the projection lens It is converted into projection light 110 by 4 and enlarged and projected on the screen 5.

The condenser lens 131 had to have the converging angle θ (see FIG. 50) as large as possible in order to improve the illumination efficiency. As a lens configuration capable of increasing θ, a configuration is known in which the lamp 120 side is a concave, flat, or convex spherical surface, and the parallel illumination light flux 2 side is an aspherical convex surface. Was at most 40 °. An example of such a condenser lens is disclosed in the literature ("Laser and Optics Guide II", pp.122-124, published by Nippon Melles Griot Co., Ltd., June 1989).
There is also an attempt to increase the converging angle θ by configuring the condenser lens 131 with a set of two to three lenses, but the light source device becomes large due to the increase in the total length of the lens, and the lens assembly becomes complicated and low cost. There was a problem such as becoming an obstacle to commercialization.

When the condenser lens 131 for collimating the light emitted from the lamp 120 into parallel light is constituted by a single lens, the parallelism of the illumination light flux 2 after passing through the condenser lens 131 differs depending on the light wavelength. This is due to the aberration (chromatic aberration) that occurs because the refractive index of the lens material changes depending on the wavelength of light.
When the condenser lens 131 is designed so that the parallelism is optimum in green light which is the central wavelength region of visible light,
Blue light on the short wavelength side becomes focused light, and red light on the long wavelength side becomes divergent light. Three liquid crystal light valves (liquid crystal panel)
Lighting conditions of 3R, 3G, 3B) are different. The optical path length from the condenser lens 131 to the liquid crystal light valve in the projection display device of the prior art is about three times as long as the optical paths of red and blue with respect to the optical path of green. Since the red light is divergent light and has a long optical path length, the decrease in illuminance on the liquid crystal light valve surface is remarkable with respect to the green light. On the other hand, since the blue light is focused light, the projection image on the screen 5 has a color unevenness in which the central portion becomes bluish.

As a method of correcting chromatic aberration of a lens, it is known to form a lens by a combination of a convex lens having a small refractive index dispersion (large Abbe number) and a concave lens having large refractive index dispersion (small Abbe number). However, the drawbacks of this lens are as follows. (1) Since the concave lens is used, the light collection angle θ becomes small. (2) Since the material having a small refractive index dispersion used for the convex lens generally has a low refractive index, it is difficult to design a lens having a large light collection angle θ. (3) The lens length becomes long and the assembly becomes complicated.

Further, since the conventional projection display device is constructed as described above, the dichroic mirrors 14R, 14B
There is also a problem that a shadow is generated at the crossing point of, and the condenser lens 131 is cracked by the heat of the lamp 120.

By the way, a TN (Twisted Nematic) type liquid crystal light valve is constituted by arranging polarizing plates in front of and behind a liquid crystal layer. The polarizing plate has a function of transmitting only polarized light in one direction and absorbing polarized light in a direction orthogonal thereto. Generally, a plastic polarizing plate is often used, and a material in which a dichroic substance such as an iodine compound or a dye is adsorbed on a polyvinyl alcohol (PVA) film is used.
It is configured to be oriented in one direction and absorb only polarized light in a specific direction.

When natural light whose polarization direction is indefinite is incident on the liquid crystal light valve, half the optical power is absorbed by the polarizing plate. In a projection display device using a liquid crystal light valve, the liquid crystal light valve is illuminated by a high-intensity light source, and light absorption in a polarizing plate causes heat generation. If the polarizing plate is used at a temperature higher than the heat-resistant temperature, the polarizing plate may be deformed or modified so that the degree of polarization is lowered and the image quality is greatly deteriorated. Especially, a liquid crystal light valve using a plastic polarizing plate has a heat resistance of only 80 to 90 ° C., which is an obstacle to obtaining a high brightness image by illuminating with high illuminance.

As a method of solving this problem, there is a method of removing polarized light in an unnecessary direction in front of the polarizing plate. This conventional example will be described with reference to FIG. Figure 51
FIG. 6 is a diagram showing an optical system of a projection type display device using a liquid crystal light valve reported in JAPAN DISPLAY ■ 89 DIGEST pp.646-649. The lamp 120 emits a parallel light flux 2 in combination with the parabolic mirror 13 and the like. The filter 12 cuts ultraviolet rays and infrared rays, and the polarizing element 6 called a pre-polarizer converts natural light whose polarization direction is indefinite into partial polarization in which the polarization direction is large only in one direction.

Next, dichroic mirrors 7a and 7b separate light into three colors of red (R), green (G) and blue (B), and the respective lights are condensed by condenser lenses 8r, 8g and 8b. After that, the liquid crystal light valves 3r, 3g, 3b sandwiched between the two polarizing plates 17r, 17g, 17b, 18r, 18g, 18b perform light modulation to form an image of three primary colors. Next, the images of the three primary colors are combined by the color combining dichroic mirrors 9a and 9b, enlarged by the projection lens 4, and the color image is enlarged and projected on the screen (not shown).

FIG. 52 is a view showing the polarizing element 6, which has a structure in which glass plates 61 are laminated. Glass plate 61
At the interface where the air layer and the glass plate layer have different refractive indices, one of the linearly polarized light (P-polarized light) 22 is entirely transmitted and the other linearly polarized light (S-polarized light) 21 is partially reflected by an incident angle (blue Star angle) is set. Polarizing direction required for liquid crystal light valves 3r, 3g, 3b by stacking multiple glass plates 61,
That is, the incident side polarization plates 17r, 17g, 17b of the liquid crystal light valve
A light beam having a polarization in the same direction as the polarization axis of is generated.

In the conventional example, since the polarization element (S-polarized light in FIG. 52) orthogonal to the polarization direction of the incident side polarization plates 17r, 17g, 17b of the liquid crystal light valve is previously removed by the polarization element 6, it absorbs light. It is possible to reduce the heat generation deterioration of the incident side polarization plates 17r, 17g, and 17b.

The polarization element 6 in the conventional example is composed of a glass plate tilted with respect to the optical axis at Brewster's angle, typically about 57 ° (when the refractive index n = 1.52). If a polarizing element is made up of one glass plate, it will be approximately
It requires a depth D of 1.5 times. The depth D can be halved if the structure is folded once as shown in FIG. In order to increase the brightness of the projection display device, it is necessary to install the lamp 120 as close as possible to the liquid crystal light valves 3r, 3g, 3b. In the conventional technology, the large-sized polarizing element 6 is an obstacle, and it is desired to realize a thinner polarizing element from the viewpoint of downsizing the projection display device.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a large-diameter condenser lens capable of making the converging angle θ larger than that of a conventionally known condenser lens, and a condenser lens thereof. An object of the present invention is to provide a light source device used and a projection display device using the light source device.

Another object of the present invention is to provide a projection display device having high brightness and excellent color uniformity, and a light source device in which a condenser lens is not damaged by heat.

Still another object of the present invention is to provide a polarizing element which is thin and has low loss.

[0019]

In both the first and second inventions of the present application, the first surface located on the large conjugate side is a convex surface, and the first surface located on the small conjugate side (lamp side). The first aspect of the invention satisfies the following condition [1], which is composed of a double-sided aspherical single lens whose two peripheral portions are concave.
The second invention satisfies the following condition [2] and has a numerical aperture of 0.9 or more. [1] 0.42 <r1 / nf <0.45 18 <| r2 /
nf | -0.39 <K1 <-0.25 0.11 <△ 2 / f <0.
14 [2] 0.4 <r1 / nf <0.6 -0.5 <r2 / n
f <-0.3-0.6 <K1 <-0.2-0.1 <SG2 / f <0.
1 However, f: focal length of the entire lens system n: refractive index of the lens r1: central curvature radius of the first surface r2: central curvature radius of the second surface K1: conical constant of the first surface Δ2: of the second surface Difference in the optical axis direction between the aspherical surface at the outermost periphery of the effective diameter and the reference spherical surface having the central radius of curvature r2 SG2: Difference in the optical axis direction with respect to the surface center of the aspherical surface at the outermost periphery of the effective diameter

Further, in the condenser lens of the first invention and the second invention, a portion having a diameter larger than the effective diameter of the second surface is a flat surface orthogonal to the optical axis, and is larger than the effective diameter of the first surface. The easiness of mounting is secured by making the diameter portion a flat surface orthogonal to the optical axis.

A light source device according to a third invention of the present application comprises a discharge lamp, a spherical mirror, and the condenser lens (NA ≧ 0.9) according to the first and second inventions, and the center of curvature of the spherical mirror and the second condenser lens. The focal point on the surface side is set as a common point, and the emission center of the discharge lamp is arranged at the common point. In addition, the first surface of the condenser lens is provided with a single-layer antireflection coating, and the second surface is provided with an infrared / ultraviolet reflection coating or an infrared reflection coating.

A projection display apparatus according to a fourth invention of the present application is an image display device, a light source for illuminating the image display device,
And a projection lens for enlarging and projecting a display image of an image display device, and applying the light source device of the third invention as a light source. Furthermore, by making the direction of the electrodes of the discharge lamp and the direction of the exhaust part of the burner part a predetermined direction with respect to the image display device, the brightness distribution of the projected image can be made uniform.

The projection type display device of the fifth invention of the present application is a lamp for white light, a light source device composed of a spherical mirror and a condenser lens, and a color for separating white light into light of three primary colors of red, green and blue. A separating means, an image display device with a rectangular aperture, a color synthesizing means for synthesizing red, green, and blue images, and a projection lens for enlarging and projecting a display image of the image display device,
To correct the parallelism of the illumination light depending on the wavelength caused by the chromatic aberration of the condenser lens, insert a concave lens in the light path of the focused light and a convex lens in the light path of the divergent light to correct the parallelism. To do.

The projection display device according to the sixth invention of the present application is the fifth invention.
In the projection display device of the invention, by using the color separation means in which two dichroic mirrors are crossed, and by setting the side direction of the intersection of the color separation means and the light emission direction of the linearly-emitting lamp to be a predetermined direction, This is to reduce the generation of shadows at intersections.

The light source device of the seventh invention of the present application is provided with a lamp, a spherical mirror and a condenser lens, and the condenser lens is divided to prevent cracking of the condenser lens due to thermal expansion.

The light source device of the eighth invention of the present application comprises a lamp, a spherical mirror and a condenser lens, and is provided with a coating for reflecting infrared light and ultraviolet light for removing an unnecessary light spectrum such as heat rays. It is applied to the side.

In the polarizing element of the ninth invention of the present application, the incident surface and the outgoing surface are folded back a plurality of times at such an angle as to transmit the P-polarized light with low loss, and the unit elements in the shape of a rhombus of the element cross section are connected at regular intervals. It has a shape, and the incident angle is set to be Brewster's angle or more, and the thickness and folding period of this polarizing element are optimized.
Also, using a plastic material for the material of this polarizing element,
It uses a filter that cuts ultraviolet rays and infrared rays. The polarizing element is forcibly cooled. Further, a plurality of polarizing elements are laminated and a spacer is inserted between the polarizing elements. Further, a projection structure is integrally formed on a part of this polarizing element to substitute a spacer, and an air layer is provided between the elements.

In the polarizing element of the tenth invention of the present application, the incident surface and the outgoing surface allow P-polarized light to pass therethrough with a low loss, the element cross section has a triangular wave shape, and the incident angle is a Brewster's angle or more. In addition, the thickness and folding cycle of the element are optimized.

The projection display apparatus of the eleventh invention of the present application uses the polarizing element of the ninth and tenth inventions.

[0030]

The condenser lens of the first invention and the second invention has the following performance. [A] Since the converging angle θ can be increased to 64.2 ° or more and the spherical aberration can be reduced, illumination light with low aberration and high efficiency can be obtained. [B] A back focus that is relatively long compared to the focal length can be secured. [C] Since the peripheral portion of the surface (second surface) on the lamp side can be concave, the incident angle to the condenser lens can be reduced and the transmittance of the peripheral portion of the lens can be improved. Further, when the surface of the light source side is coated with a multilayer film, the incident angle dependence of the transmission characteristics can be reduced. [D] By making the outside of the effective diameter of the surface (second surface) on the lamp side a flat surface, a large working distance can be secured. If the outer surface of the effective diameter of the first surface is a flat surface, the lens holding flange can be formed together with the flat surface on the second surface side, which facilitates mounting.

According to the light source device of the third invention, the converging angle θ is
A highly efficient illumination light source using a condenser lens of 64.2 ° or more can be realized. Moreover, since the condenser lens is a single lens, a small light source device can be obtained.

According to the projection type display apparatus of the fourth invention, the image display device can be illuminated with high illuminance, and since the aberration of the illumination light is small, a high-luminance projection image can be obtained. Moreover, since the light source is highly efficient, the power consumption of the device can be small.

According to the projection type display apparatus of the fifth aspect of the invention, since the parallelism of the illumination light is corrected by the lens, the illuminance on the liquid crystal light valve surface is reduced due to the difference in the optical path, and the three liquid crystal light valves are arranged. The non-uniformity of lighting is eliminated.

According to the projection type display device of the sixth invention, the uneven illumination of the image display portion caused by the shadow of the intersection of the two filters is reduced, and a uniform projected image having no uneven brightness is obtained.

According to the light source device of the seventh aspect of the present invention, since the condenser lens is divided in advance, it is possible to prevent cracks caused by volume change due to thermal expansion.

According to the light source device of the eighth aspect of the present invention, since the coating for reflecting the infrared light and the ultraviolet light is applied to the light incident surface side, unnecessary light spectrum such as heat rays is removed, and the optics such as a condenser lens is removed. Reduces thermal degradation of parts.

According to the polarizing element of the ninth invention, the shape thereof is thin, P-polarized light is transmitted without loss when the incident angle is Brewster's angle, and P-polarized light is transmitted by optimally designing the thickness. Efficiency is improved. Further, when the incident angle is set to be equal to or greater than the Brewster angle, P-polarized light is slightly lost, but the transmittance of S-polarized light is further reduced, so that the extinction ratio is improved. Further, by using a plastic material as the material of the polarizing element, it is possible to integrally and easily manufacture an element having a complicated shape at low cost. Also,
By using an ultraviolet / infrared cut filter together and further performing forced cooling, it is possible to prevent thermal deformation / degeneration of the polarizing element itself. Further, the extinction ratio is improved by stacking a plurality of polarizing elements. Further, by inserting a spacer between the polarizing elements to secure an air layer, deterioration of the extinction ratio due to multiple reflection is prevented.

According to the polarizing element of the tenth aspect of the invention, since the cross-sectional shape is triangular, the layer thickness is uniform and the mechanical strength is strong, and the incident angle is a Brewster's angle or more. As described above, the thickness of the element and the folding cycle are optimized, so that the transmission efficiency of P-polarized light is improved.

According to the projection type display device of the eleventh aspect of the invention, by applying the polarizing element of the ninth and tenth aspects of the invention, it is possible to reduce the heat generation of the incident side polarization plate of the liquid crystal light valve, and it is possible to achieve higher brightness and compactness. A projection display device can be realized.

[0040]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments thereof. Example 1. (Large-Diameter Condenser Lens) Regarding the characteristics of the large-diameter condenser lens for a short arc length discharge lamp, the main specifications to be considered other than the converging angle (or NA) are as follows. (A) A sufficient back focus and working distance (WD) can be secured. (B) Satisfying a desired irradiation light beam diameter. (C) Spherical aberration is small, and an object having an arc length of about a small conjugate side can be sufficiently resolved. (D) Easy mounting of the lens.

As the application example, the condenser lens of the present embodiment is assumed to be the liquid crystal projection display device described in the prior art. In that case, the arc length of the discharge lamp is 1 to 5 mm, and the irradiation luminous flux diameter is 48 to 50 mm. Further, although the NA of the lens is 0.9 or more, it is possible to intentionally use a small NA easily by using a known diaphragm or the like.

The condenser lens of this embodiment will be described below with reference to the drawings. 1 and 2 are lens cross-sectional views corresponding to Examples 1 and 4 of Example 1 described later. In FIG. 1, various symbols necessary for explaining the embodiment are also shown. In FIG. 1, S1 is a large conjugate side surface (first surface)
And S2 is the surface (second surface) on the small conjugate side (discharge lamp side). d1 is the central thickness of the condenser lens lens 131. Si is the arc of the discharge lamp, and is drawn in the figure assuming a length of 5 mm in the direction orthogonal to the optical axis. D1 and D2 represent the effective diameters of the first surface S1 and the second surface S2, respectively, and as indicated by the broken line, S2 from the small conjugate side axis.
A light ray incident on the area within the diameter D2 of the surface exits as a parallel light beam 2 from the area within the diameter D1 of the S1 surface. θ
Is the maximum converging angle, and the numerical aperture (NA) of the condenser lens is defined by equation (1) using θ. NA = sin (θ) (1)

Reference numeral 132 is a flat surface provided on the second surface S2 outside the effective diameter D2. A flat portion 143 is also provided outside the effective diameter D1 of the first surface S1, and the flange is formed by the flat portions 132 and 143.
133 is formed integrally with the condenser lens 131.
The flange 133 is used to facilitate holding of the condenser lens 131, as described below in connection with Examples 2 and 3. d2 is the arc S from the center of the second surface S2
The distance to the center of i (back focus), WD is the distance from the flat surface 132 to the arc Si (working distance).
Reference numeral 2 denotes a collimated illumination light flux which is emitted from the center of the arc Si at the maximum converging angle θ and is collimated by the condenser lens 131.
The flat surfaces 132 and 143 do not have to be mirror surfaces in particular, and may be in the form of frosted glass or a state in which black paint is applied to the surfaces to prevent unnecessary light.

The first surface S1 is a convex aspherical surface, and the second surface S1.
2 is a concave aspherical surface with a strong peripheral portion. A lens having a convex peripheral portion may be considered, but a concave peripheral portion has a smaller incident angle of a light beam incident on the periphery of the S2 surface, and thus has a higher transmittance and thus higher efficiency. As shown concretely by a numerical example, the absolute value of the central radius of curvature of the second surface S2 is much larger than that of the first surface S1, so that the vicinity of the center looks like a plane.

The lens system of this embodiment has the above-mentioned specifications (a).
In order to achieve (c) to (c), the following conditional expressions are satisfied in the above double-sided aspherical single lens configuration. 0.42 <r1 / nf <0.45 (2) 18 <| r2 / nf | (3) -0.39 <K1 <-0.25 (4) 0.11 <△ 2 / f <0.14 (5) However, f: focal length of the entire lens system n: refractive index of the lens r1: central radius of curvature of the first surface S1 r2: central radius of curvature of the second surface S2 K1: conical constant of the first surface S1 Δ2: second surface S2 Is the difference in the optical axis direction between the aspherical surface and the reference spherical surface having the central radius of curvature r2 at the end of the effective diameter of, and the direction in which the peripheral portion of the second surface S2 bends to the smaller conjugate side is positive.

The meanings of the lower limit value and the upper limit value of the above conditional expression will be described below. First, in the formula (2) that defines the ratio of the central radius of curvature r1 of the first surface S1 to the value obtained by multiplying the refractive index n by the focal length f, if the lower limit value is exceeded, the refractive power is biased to the first surface S1. Working distance (WD) and back focus cannot be obtained. On the contrary, if the upper limit is exceeded, even if an attempt is made to correct a large spherical aberration generated on the second surface S2, if the spherical aberration in the vicinity of the axis is corrected, the zonal aberration becomes large, and an unacceptable under spherical aberration in the maximum zonal portion. Remains. If an attempt is made to correct the spherical aberration in this maximum annular zone, an unacceptable amount of spherical aberration will remain in the intermediate annular zone.

Equation (3) is obtained by using the center curvature radius r2 of the second surface S2.
Is a condition for determining the absolute value of the ratio of the value obtained by multiplying the refractive index n by the focal length f, and if the lower limit is exceeded, the third-order spherical aberration in the vicinity of the axis becomes under. According to the condition of the equation (3), the vicinity of the center of the second surface S2 has a shape close to a plane.

Equation (4) is a condition for satisfactorily correcting high-order spherical aberration, and when the lower limit value is exceeded, if spherical aberration near the axis is corrected, the magnitude is unacceptable near the maximum annular zone. Excessive spherical aberration occurs. On the contrary, if the upper limit of the expression (4) is exceeded, an unacceptable high-order spherical aberration near the maximum annular zone will occur if the spherical aberration near the axis is corrected.

Expression (5) is a condition that defines the ratio of the aspherical surface amount Δ2 and the focal length f at the end of the effective diameter of the second surface S2 (surface on the side of the discharge lamp). If the upper limit of expression (5) is exceeded, the desired NA cannot be obtained because the surface inclination of the effective diameter peripheral portion of the second surface S2 becomes too large in a concave shape. Further, it becomes impossible to secure a large working distance (WD). When the value goes below the lower limit of the expression (5), the converging angle can be increased conversely, but large high-order spherical aberration occurs in the ring zone, which makes correction thereof difficult.

Next, specific numerical examples of the first embodiment are shown in Tables 1 to 6. The symbols shown in Tables 1 to 6 have the following meanings. f: Focal length of the entire condenser lens system NA: Numerical aperture on the second surface S2 side (small conjugate side) β: Reference imaging magnification when light rays enter from the large conjugate side WD: Working distance (see FIG. 1) D1 : Effective diameter (diameter) of the first surface S1 D2: Effective diameter (diameter) of the second surface S2 n: Lens refractive index (n1) △ 2: Effective diameter of the second surface S2 Aspherical amount at the end m: Large Surface numbers sequentially counted from the conjugate side ri: Center curvature radius of the i-th lens surface counted from the large conjugate side di: Thickness and air gap of the i-th lens component counted from the large conjugate side ni: Large conjugate side The refractive index of the i-th lens component at the wavelength of 546.1 nm (e-line) counting from νi: Abbe number of the i-th lens component counting from the large conjugate side. Cartesian coordinate system with origin as the optical axis and Z-axis ( , Y, in Z), r
Is the central radius of curvature, K is the conic constant, A4, A6, A8, A
When 10 is a 4th-order, 6th-order, 8th-order, and 10th-order aspherical coefficient, it shall be represented by Formula (6).

[0051]

[Equation 1]

At this time, Δ2 is expressed by the following equation (7). Δ2 = Zas−Zsp (7) However, Zas and Zsp use the effective diameter D2 of the second surface S2,
They are given by the following equations (8) and (9), respectively.

[0053]

[Equation 2]

(Example 1) Table 1 shows numerical data in Example 1 of Example 1.

[0055]

[Table 1]

As a glass material, FD13 (Hoya Corporation)
Manufactured) was used. FIG. 3 is a spot diagram on the paraxial image plane on the small conjugate side at a wavelength of 546.1 nm (e line), and each X point corresponds to one light ray. 312 for calculation
I traced the rays of a book.

In Example 1, since the spherical aberration was sufficiently corrected, a spot diameter of about 0.5 mm was obtained despite the large aperture of NA = 0.917 (θ = 66.5 °).
Therefore, since an object (arc length) of about 1 to 5 mm can be sufficiently resolved, when a light ray is incident from the second surface S2 side,
A parallel illumination light flux 2 with low aberration close to the limit determined by the arc length can be obtained.

(Example 2) Table 2 shows numerical data in Example 2 of Example 1.

[0059]

[Table 2]

As the glass material, FD4 (manufactured by HOYA Co., Ltd.)
It was used. In Example 2, the luminous flux diameter (D1) is about the same as in Example 1, and a larger NA is obtained.

(Example 3) Table 3 shows numerical data in Example 3 of Example 1.

[0062]

[Table 3]

As a glass material, FD14 (HOYA Co., Ltd.)
Manufactured) was used. In Example 3, a larger NA is obtained than in Example 1.

Example 4 FIG. 2 shows a sectional view of Example 4 of Example 1. Table 4 shows numerical data in Example 4.

[0065]

[Table 4]

As the glass material, FD6 (manufactured by HOYA Co., Ltd.)
It was used. In Example 4, the luminous flux diameter (D1) is 1 mm as compared with Example 1.
Although small, the increase in NA is large.

(Example 5) Table 5 shows numerical data in Example 5 of Example 1.

[0068]

[Table 5]

As a glass material, FD6 (manufactured by HOYA Corporation)
It was used. In Example 5, the luminous flux diameter (D1) is 1 mm as compared with Example 1.
Although smaller, the NA is even larger than in Example 4.

(Example 6) Table 6 shows numerical data in Example 6 of Example 1.

[0071]

[Table 6]

As a glass material, NbFD13 (HOYA
(Manufactured by K.K.) was used. In Example 6, the luminous flux diameter (D
1) is as small as 1 mm, but the increase in NA is large.

FIG. 4, FIG. 5, FIG. 6, FIG. 7, FIG.
FIG. 9 is an aberration diagram in a paraxial image plane on the small conjugate side, which corresponds to Example 1, Example 2, Example 3, Example 4, Example 5, and Example 6 of Example 1, respectively. The spherical aberration diagram is (WL1 = 610 nm, WL2 = 546.1
nm, WL3 = 470 nm), and astigmatism is 546.1 nm (e line). The astigmatism was calculated assuming a maximum image height of 2.5 mm assuming a lamp with an arc length of 5 mm. The spherical aberration and astigmatism in each aberration chart are good values that are sufficiently practical.

Example 2. (Light Source Device) (Example 1) By using the large-diameter condenser lens in the first embodiment, a small and highly efficient light source device for illumination can be configured. FIG. 10 is a configuration diagram of the light source device in Example 1 of the second embodiment. 131 is a condenser lens, 143 is a first flat portion formed on the outer periphery of the effective diameter of the first surface S1 of the condenser lens 131, and 132 is Second surface S2 of condenser lens 131
Second flat portion formed on the outer periphery of the effective diameter of
The flange portion is sandwiched between the flat portion 143 and the second flat portion 132 and is formed integrally with the condenser lens 131.

Reference numeral 120 is a discharge lamp, and a metal halide lamp, a xenon lamp or the like is actually used. 121
Is an electrode of the lamp 120, and 122 is a shaft portion that seals the electrode 121 and is made of a glass material. Reference numeral 123 denotes a burner portion of the lamp 120, which is made of glass, a translucent ceramic material, or the like, and various kinds of gases and elements necessary for light emission are enclosed in an internal cavity, and a discharge gap 124 between a pair of electrodes 121 is provided. The desired emission spectrum is obtained by discharging at. Lamp 120
Is located on the side of the second surface S2 of the condenser lens 131, the discharge gap 124 corresponds to the image plane Si on the small conjugate side in Example 1 (FIGS. 1 and 2), and the shaft portion 122 is of the condenser lens 131. It is arranged so as to be orthogonal to the optical axis (chain line).

Reference numeral 130 is a reflecting mirror, and the surface 144 on the concave surface side is mirror-finished and has a reflecting coating. 13
Reference numeral 7 denotes a flange portion provided on the outer peripheral portion of the effective diameter of the reflecting mirror 130. The reflecting mirror 130 is typically arranged such that the center of curvature of the concave surface 144 is located at the center of the discharge gap 124 (light emission center). 134 is the first support plate and 138 is the second
Support plate, 135 is the first stop, 139 is the second stop,
136 is the first screw and 142 is the second screw.

Next, the operation of the first example will be described. The lamp 120 is driven by a circuit (not shown) that causes a discharge between a pair of electrodes 121 as is known, and the arc of the discharge heats the inside of the burner portion 123 to emit light. When the lamp 120 is driven by alternating current, an arc is generated linearly in the direction of the electrode 121 in the part of the discharge gap 124. The center of the discharge gap 124 is located at the focal position on the second surface S2 side of the condenser lens 131, and the light flux emitted from the center of the discharge gap 124 and directly incident on the condenser lens 131 passes through the condenser lens 131. It is converted into a parallel illumination light flux 2.

On the other hand, the light flux emitted from the central portion of the discharge gap 124 and incident on the reflecting mirror 130 has the center of curvature of the concave surface 144 aligned with the center of the discharge gap 124. The light travels in the same path in the reverse direction, is condensed again at the center of the discharge gap 124, and enters the condenser lens 131. The reflectance of the concave surface 144 is 10 in the desired wavelength range.
Condenser lens 131 by setting it near 0%
The output power from is about 2 compared to the case without the reflector 130.
Double. The concave surface is used to determine the effective diameter of the reflector 130.
If the effective reflection area of 144 is larger than the area where the maximum converging angle θ of the condenser lens 131 is possible, the maximum luminous flux can be converted into the illumination luminous flux 2.

The radius of curvature of the concave surface 144 of the reflecting mirror 130 is preferably small in terms of downsizing the light source device 1 as a whole, but as the radius is shortened, astigmatism increases with respect to imaging at the end of the arc length. In addition, it is not preferable from the viewpoint of securing the arrangement margin of the lamp 120 with respect to the shaft portion 122. The present inventor has analyzed the aberration characteristics of the entire light source device 1 by ray tracing, and as a result, when the radius of curvature of the concave surface 144 is combined with the condenser lens of Embodiment 1, the first surface S of the condenser lens 131 is used.
It has been found that it is suitable to make it 1/2 or more of the effective diameter D1 of 1.

The condenser lens 131 is fixed by a flange 133 which is integrally provided outside the effective diameter. Figure
In the example of 10, the flat surface 132 is pressed against the support plate 134 arranged on the second surface S2 side to position the stopper 135 on the flat surface.
The condenser lens 131 is held by pressing it against 143 and fixing it to the support plate 134 with screws 136. Reflector 13
0 means that the flange 137 integrally provided on the outer periphery is pressed against the support plate 138, and the stopper 139 is provided on the opposite side of the flange 137.
It is held by being fixed to the support plate 138 with the screw 142 while being pressed.

The first support plate 134 has a hole in its center so that the light beam emitted from the lamp 120 is incident on the second surface S2 of the condenser lens 131. In addition, the second support plate 138 also has a concave surface 14 for directing light rays emitted from the lamp 120.
There is a hole in the center to make it incident on 4.

The first and second surfaces S1, of the condenser lens 131
S2 contains an anti-reflective coating (eg 38
0 to 780 nm wavelength range), UV / infrared light reflective coating (eg 400 nm or less, 700 nm wavelength or more reflective), infrared light reflection coating (eg 700 nm wavelength band or more) Reflection) is applied. The type of these coatings and the surface to which the coating is applied are determined according to the use of lighting, but the coating may not be necessary depending on the use. As an example, coating used in the light source device 1 of the liquid crystal projection display device shown in FIG. 50 will be described below.

In the liquid crystal projection display device, the light source device 1 needs to emit white light over the entire visible light range. Also,
Since the liquid crystal panels 3R, 3G, 3B are deteriorated in characteristics due to infrared rays (heat rays) and ultraviolet rays, it is necessary to remove light rays other than visible light from the irradiation light as much as possible. If the surface of the condenser lens 131 is coated with an ultraviolet / infrared light reflection coating or an infrared light reflection coating, it is effective in reducing the heat rays contained in the illumination light flux 2. As is well known, it is necessary to form the above-mentioned coating by a multi-layer thin film, but the incident angle dependence of the transmission characteristics poses a problem. However, the second of the condenser lens 131
Since the periphery of the surface S2 is concave and the increase of the incident angle can be suppressed, the uniformity of the transmission characteristics can be improved as compared with the conventional flat incidence condenser lens (FIG. 50). To this end,
An infrared light reflecting coating or an infrared light reflecting coating is suitably applied to the second surface S2.

Further, since the incident angle of the peripheral portion of the first surface S1 tends to be large, the influence of the incident angle dependence of the spectral transmittance can be minimized by applying a single-layer antireflection coating. it can. The concave surface 144 is coated with a highly reflective metal thin film such as Al or Au, or a coating that transmits infrared / ultraviolet light or a coating that transmits infrared light is used to form an unnecessary light spectrum included in the illumination light flux 2. It can be reduced.

(Example 2) In Example 1, the focal point of the condenser lens 131 and the center of curvature of the concave surface 144 are arranged at the center of the discharge gap 124 so as to coincide with each other. However, when a xenon lamp that is lit by direct current is used as the lamp 120, the configuration described below is more preferable.
As is well known, the DC drive type xenon lamp has an asymmetrical electrode structure on the anode side and the cathode side, and is generally thin on the cathode side and thick on the anode side. It is known that the vicinity of the tip of the cathode emits a very small point light source. As an example, XBO250 from Osram (Germany)
The emission luminance distribution between 0W type electrodes is shown in FIG. In this example, it can be seen that most of the light energy is concentrated at the tip portion of the cathode 121C having a diameter of about 0.5 mm or less, although the electrode interval is about 6 mm.

As described above, in the DC-driven xenon lamp, the light emitting point is localized at the tip of the cathode. Therefore, by arranging this light emitting point along the optical axis of the light source device, the traveling direction of the emitted light is increased. Can be aligned with the optical axis. FIG. 11 shows the arrangement of the light source device in Example 2 of Example 2 in consideration of the above matters. In FIG. 11, 120 is a xenon lamp as a discharge lamp, 121A and 121C are xenon lamps 12 respectively.
0 anode and cathode. Figures for other components
Similar to 10.

In FIG. 11, the tip of the cathode 121C is arranged on the optical axis of the condenser lens 131 (shown by the chain line) and at the focal position. Further, the center of curvature of the concave surface 144 is also aligned with the tip of the cathode 121C. By arranging in this way, the traveling direction of the emitted illumination luminous flux 2 can be exactly aligned with the optical axis of the condenser lens 131, so that the present light source device is used as the light source device 1 of the liquid crystal projection display device of FIG. When applied to, the installation becomes easy. Figure 11
Is the same as the embodiment of FIG. 10 except that the discharge lamp is the xenon lamp 120 having the cathode 121C and the anode 121A, and therefore the description of the operation is omitted.

Example 3. (Projection Display Device) By replacing the light source device in the second embodiment with the light source device 1 of the conventional liquid crystal projection display device shown in FIG. 50, a high brightness liquid crystal projection display device can be realized. As described in connection with the first embodiment, the light flux emitted from the light source is NA ≧
The first reason is that a condenser lens with a large diameter of 0.9 can be used for efficient irradiation. The second reason is that since the aberration of the illumination light is extremely small, the luminous flux can be incident on the projection lens 4 with high efficiency.

Conventionally, since a non-telecentric lens having a small diameter is used as the projection lens 4, a liquid crystal panel is used.
Place a condenser lens (not shown) near 3R, 3G, 3B,
A method of improving the incidence efficiency of the light flux on the entrance pupil (not shown) of the projection lens 4 is also used. Even when the light source device of the second embodiment is applied to such a configuration of the projection display device in which the condenser lens is arranged near the liquid crystal panel, a high-luminance projection image can be obtained. This is because the aberration of the illumination light flux 2 is small and a very small light source image can be formed on the entrance pupil of the projection lens by the condenser lens, so that the transmission light flux of the projection lens 4 can be maximized.

The brightness uniformity of the projected image changes depending on the direction of the screen of the liquid crystal panel and the attitude of the lamp depending on the light distribution characteristics of the lamp 120. This will be described with reference to FIG. 13, and an optimal lamp arrangement method will be described with reference to FIG. Figure 13
(A) is a definition diagram of a rotation angle ψ of the lamp 120 around the electrode 121 and an inclination angle θ from the electrode direction. The light distribution characteristics of the lamp 120 with respect to these two types of angles θ and ψ are shown in FIG.
It changes as shown in FIG. 13 (c). That is, the luminous intensity is minimum in the electrode direction and maximum in the direction orthogonal to the electrode with respect to the angle change in the θ direction.

Further, basically, there is almost no change in luminous intensity with respect to the change in angle in the ψ direction. However, the burner part of the lamp 120
An exhaust portion 125 (which is a portion where the air inside the burner is exhausted and glass material is fused and is often located on the side surface of the burner) is formed in 123 in the manufacturing process. The luminous intensity tends to decrease in the direction corresponding to.

Considering the light distribution characteristics of the lamp 120 described above, the lamp arrangement in the case of applying the light source device of the second embodiment to the projection type display device shown in FIG. 50 makes the luminance distribution of the projected image uniform. Can be optimized from the viewpoint. The optimum lamp arrangement will be described below with reference to FIG.

Reference numeral 3 denotes a display screen of the liquid crystal panel of the projection type display device, and only one screen is shown for convenience of explanation. 3H and 3V indicate the long side and the short side of the rectangular screen 3, respectively. (X, Y, Z) is an orthogonal coordinate system, Z is oriented in the optical axis direction of the condenser lens 131, and X, Y are long sides 3
The direction of H and the short side is 3V. As shown, by directing the electrode 121 and the short side 3V in the same Y direction, the lamp 12
Direction in which illuminance unevenness occurs due to 0 light distribution characteristics (θ direction in Fig. 13)
Can be adjusted to the short side direction, and the direction of the long side direction 3H corresponds to the ψ direction in which the unevenness of light intensity is small, so that the uneven illuminance can be reduced. Therefore, the uneven brightness of the projected image can be reduced.

Contrary to this arrangement, if the direction of the electrode 121 is aligned with the direction of the long side 3H (X direction), the θ direction with a large change in luminous intensity corresponds to the long side 3H direction. The illuminance unevenness on the panel 3 and hence the brightness unevenness of the projected image becomes larger than the above-described optimum arrangement. Also, the lamp 12
By arranging the exhaust part 125 so as to be located in the X direction (or −X direction) by setting around the electrode 121 of 0, it is possible to minimize the influence of the decrease in the light intensity due to the exhaust part 125, and thus the projection is further performed. The uneven brightness of the image can be reduced.

In the above embodiments, the light source device according to the second embodiment is applied to the liquid crystal projection display device.
In addition to this, as a device that applies the light source device for lighting,
A slide projector, a microfilm reading device, a search light, an automobile headlight and the like are known. It goes without saying that the light source device according to the second embodiment can realize a device with high efficiency and low power even when applied to these devices.

Example 4. (Large-Aperture Condenser Lens) In Example 1, a large-aperture condenser lens with NA ≧ 0.9 using a glass material having a relatively high refractive index (n> 1.7) was disclosed. However, as a result of experiments, it was found that when a light source device is configured using a discharge lamp that consumes a large amount of power (> 200 W), the lens may break depending on the cooling conditions. Therefore, the lens was designed by using a glass material having excellent heat resistance (Corning Corporation 7740). Since this glass material has a low refractive index of 1.47 at the d-line, it is more difficult to realize NA ≧ 0.9 than in Example 1, but this time, the conditions under which the diameter can be increased have been found. Moreover, since the Abbe number is 1.6 to 2.6 times larger than that of the glass material of Example 1, the axial chromatic aberration is reduced in principle and the color unevenness of the illumination light can be reduced.

In the fourth embodiment, in addition to the specifications (a) to (d) considered in the first embodiment, the following specification (e) is also particularly considered. (E) The lens material has sufficient heat resistance so that the lens will not crack even if it is placed in the vicinity of a discharge lamp that becomes hot during light emission.

The condenser lens of the fourth embodiment is assumed to be the liquid crystal projection display device described in the prior art as an application example. In that case, numerical examples are shown in which the arc length of the discharge lamp is 1 to 5 mm and the irradiation light beam diameter is 91 to 94 mm (or 48 to 51 mm). Further, although the NA of the lens is 0.9 or more, it is possible to intentionally use a small NA easily by using a known diaphragm or the like.

The condenser lens of the present invention will be described below with reference to the drawings. Figure 15, Figure 17, Figure 19, Figure 21
[Fig. 8A] is a lens sectional view corresponding to Examples 1, 4, 6, and 7 of Example 4 described later. In FIG. 15, various symbols necessary for explaining the example are also shown. The various symbols in FIG. 15 are the same as those in FIG. 1 (Embodiment 1) except that WD is the distance (working distance) in the optical axis direction from the most protruding point on the small conjugate side of the second surface S2 to the arc Si. The same, and the numerical aperture (N
The definition of A) is the same as that of the first embodiment (equation (1)).

The first surface S1 is a convex aspherical surface, and the second surface S1.
2 is an aspherical surface with a concave peripheral portion. A lens with a convex peripheral portion is also conceivable, but a concave peripheral portion is S2.
Since the incident angle of the light ray incident on the periphery of the surface becomes small, the transmittance becomes large and the efficiency can be made higher. As shown concretely by numerical examples, the absolute value of the central radius of curvature of the second surface S2 must be equal to or less than the radius of curvature of the first surface S1 because the lens is made of a material having a relatively low refractive index. And, the central part has a convex shape.

The lens system of Example 4 has the above-mentioned specifications (a).
In order to achieve (c), the following conditional expressions are satisfied in the double-sided aspherical single lens configuration. 0.4 <r1 / nf <0.6 (10) -0.5 <r2 / nf <-0.3 (11) -0.6 <K1 <-0.2 (12) -0.1 <SG2 / f <0.1 (13 ) However, f: focal length of the entire lens system n: refractive index of the lens r1: central curvature radius of the first surface r2: central curvature radius of the second surface K1: conical constant of the first surface SG2: effective of the second surface The difference in the optical axis direction with respect to the surface center of the aspherical surface at the outermost periphery of the diameter is the positive direction in which the second surface peripheral portion bends to the smaller conjugate side.

The meanings of the lower limit value and the upper limit value of the above conditional expression will be described below. First, the meanings of the equations (10) and (12) are the same as those of the equations (2) and (4) of the first embodiment, and the description thereof will be omitted.

In the equation (11), if the upper limit is exceeded, the third-order spherical aberration near the axis becomes under. On the other hand, when the value goes below the lower limit, the third-order spherical aberration near the axis becomes excessive and cannot be controlled by the aspherical term.

Formula (13) is the second surface S2 (surface on the lamp side).
This is a condition that defines the ratio of the focal length f to the position SG2 in the optical axis direction with respect to the surface center of the aspherical surface at the end of the effective diameter. If the upper limit of expression (13) is exceeded, the surface inclination around the effective diameter of the second surface becomes too large in a concave shape, so the desired NA is obtained.
Can't get Further, it becomes impossible to secure a large working distance (WD). When the value goes below the lower limit of the expression (13), on the contrary, the converging angle can be increased, but a large high-order spherical aberration occurs in the ring zone, which makes correction thereof difficult.

Next, numerical examples of the fourth embodiment will be shown. Meanings of symbols described in Tables 7 to 15 showing numerical examples are as follows. WD: working distance (see FIG. 15) SG2: optical axis direction position with respect to the center of the aspherical surface at the effective diameter end of the second surface The meanings of the symbols other than the above are the same as in Example 1, and each surface The aspherical shape of is also expressed in the same manner as in Example 1 (see the equation (6)). Further, SG2 is expressed by the following equation (14). SG2 = Zas (14) However, Zas is expressed by the above equation (8).

Example 1 FIG. 15 is a sectional view of a condenser lens in Example 1 of Example 4. Table 7 shows the numerical data of Example 1. FIG. 16 is a spot diagram on the paraxial image plane on the small conjugate side at a wavelength of 546.1 nm (e line), and each X point corresponds to one light ray. About 30 for calculation
0 rays were traced. Since the spherical aberration is sufficiently corrected, the spot diameter is 0.5 mm or less despite the large aperture of NA = 0.917 (θ = 66.5 °).
Therefore, an object (arc length) of about 1 to 5 mm can be sufficiently resolved, and when a light ray is incident from the second surface S2 side, a parallel illumination light flux 2 with low aberration close to the limit determined by the arc length.
Is obtained.

[0107]

[Table 7]

(Example 2) Table 8 shows numerical data in Example 2 of Example 4. In Example 2, the NA is the same as in Example 1 and a slightly larger luminous flux diameter D1 is obtained.

[0109]

[Table 8]

(Example 3) Table 9 shows numerical data in Example 3 of Example 4.

[0111]

[Table 9]

Example 4 FIG. 17 is a sectional view of a condenser lens in Example 4 of Example 4. Table 10 shows the numerical data of Example 4. FIG. 18 is a spot diagram on the paraxial image plane on the small conjugate side at a wavelength of 546.1 nm (e line), and each x point corresponds to one light ray. About 30 for calculation
0 rays were traced. Since the spherical aberration is sufficiently corrected, the spot diameter is about 0.05 mm despite the large aperture of NA = 0.917 (θ = 66.5 °).
Therefore, an object (arc length) of about 1 to 5 mm can be sufficiently resolved, and when a light ray is incident from the second surface S2 side, a parallel illumination light flux 2 with low aberration close to the limit determined by the arc length can be obtained. This Example 4 has a shorter focal length than Examples 1 to 3,
Illumination beam diameter D1 is as small as 50 mm

[0113]

[Table 10]

(Example 5) Table 11 shows numerical data in Example 5 of Example 4. This example 5 has the same specifications as the example 4.

[0115]

[Table 11]

Example 6 FIG. 19 is a sectional view of a condenser lens in Example 6 of Example 4. Table 12 shows the numerical data of this Example 6. Figure 20 is a spot diagram on the paraxial image plane on the small conjugate side at a wavelength of 546.1 nm (e-line), where each x point corresponds to one ray. About 30 for calculation
0 rays were traced. Since the spherical aberration is sufficiently corrected, the spot diameter is about 0.4 mm despite the large aperture of NA = 0.908 (θ = 65.2 °).
Therefore, an object (arc length) of about 1 to 5 mm can be sufficiently resolved, and when a light ray is incident from the second surface S2 side, a parallel illumination light flux 2 with low aberration close to the limit determined by the arc length.
Is obtained.

[0117]

[Table 12]

Example 7 FIG. 21 is a sectional view of a condenser lens in Example 7 of Example 4. Table 13 shows the numerical data of Example 7. In Example 7, SG2 has a larger positive value than in Examples 1 to 6, and it can be seen from FIG. 21 that the peripheral portion of the second surface S2 protrudes toward the image plane side.

[0119]

[Table 13]

(Example 8) Table 14 shows numerical data in Example 8 of Example 4. Example 8 has almost the same specifications as Example 7.

[0121]

[Table 14]

(Example 9) Table 15 shows numerical data in Example 9 of Example 4. In this Example 9, the largest working distance WD can be secured as compared with Examples 4 to 8 of similar specifications.

[0123]

[Table 15]

22 to 30 are aberration diagrams on the paraxial image plane on the small conjugate side corresponding to Examples 1 to 9 of Example 4, respectively. The spherical aberration diagram is (WL1 = 610 nm, WL2 = 546.1
nm, WL3 = 470 nm), and astigmatism is 546.1 nm (e line). Also, astigmatism is 2.5mm maximum image height assuming a lamp with an arc length of 5mm.
Was calculated as The spherical aberration and astigmatism in each aberration chart are good values that are sufficiently practical. Note that Fig. 17, Fig. 19,
In FIG. 21, the flange portion 133 shown in FIG. 15 showing Example 1 is omitted, but it goes without saying that if the flange portion 133 is provided on the outer circumference of the lens as in FIG. 15, it can be used for mounting a lens.

Example 5. (Light Source Device) By using the large-diameter condenser lens of the fourth embodiment, a compact and highly efficient light source device for illumination can be configured. FIG. 31 is a configuration diagram of such a light source device of the fifth embodiment. 31, the same parts as those in FIG. 10 (Embodiment 2) are designated by the same reference numerals, and the description thereof will be omitted. In addition, also in Example 5,
Similar to the second embodiment, the condenser lens 131 and the reflecting mirror 13
Although 0 is fixed by pressing the flange portions 133 and 137 to an appropriate supporting plate, the detailed structure will be omitted.

The operation of the fifth embodiment is similar to the operation of the second embodiment described above, and the description thereof will be omitted.

Also in the fifth embodiment, as in the second embodiment, when the concave surface 144 is combined with the condenser lens of the fourth embodiment, the radius of curvature should be 1/2 or more of the effective diameter D1 of the first surface of the condenser lens 131. Is appropriate. Further, similarly to the second embodiment, the surfaces S1 and S2 of the condenser lens 131 may be coated with a non-reflection coating, an ultraviolet / infrared light reflection coating, or an infrared light reflection coating, if necessary. An example of coating when the light source device of the fifth embodiment is used as the light source device 1 of the liquid crystal projection display device of FIG. 50 is the same as that of the second embodiment.

Example 6. (Projection Display Device) If the light source device (FIG. 31) of the fifth embodiment is replaced with the light source device 1 of FIG. 50 showing a conventional liquid crystal projection display device, the third embodiment
Similarly, a high-brightness liquid crystal projection display device can be realized.
The reason why a high-brightness liquid crystal projection display device can be realized,
The principle and application example of the light source device are the same as those in the third embodiment, and thus the description thereof is omitted.

Example 7. (Projection Display Device) FIG. 32 is a diagram showing the configuration of the projection display device in the seventh embodiment. In the figure, the parts with the same numbers as in FIG. 50 indicate the same members. Lamp 120, reflector 130, condenser lens
The light source device 1 including 131 includes a condenser lens 13
When 1 is composed of a single lens, the parallelism of the illumination light flux 2 varies depending on the wavelength of light due to chromatic aberration as described above. When the condenser lens 131 is designed so that the parallelism is optimal for green light, which is the central wavelength region of visible light, blue light on the short wavelength side becomes focused light and red light on the long wavelength side becomes divergent light. The lighting conditions of the three liquid crystal light valves are different. In the seventh embodiment, in order to correct the parallelism, the dichroic mirrors 14B and 14R perform color separation into red, green, and blue light, and then a convex lens 16 is provided in the red optical path of the divergent light and a focused light B
A concave lens 17 is inserted in the light to correct the parallelism of each light. In order to reduce the chromatic aberration, a material having a small refractive index dispersion (large Abbe number) may be used as the material of the condenser lens 131. Generally, a material having a small refractive index dispersion has a small refractive index, so that the converging angle θ is small. It becomes difficult to design a lens having a large light collection efficiency. Conversely, if a material with a high refractive index is used, it is easy to design a lens with a large collection angle θ, but the refractive index dispersion is large (the Abbe number is small),
Correction lenses 16 and 17 with large chromatic aberration and strong power are required.

When the condenser lens described in Example 1 of Example 1 is applied to the light source device of this projection display device, the focal lengths of blue light and red light differ by about 1 mm. The blue light is a focused light that is condensed at about 1400 mm on the condenser lens transmission side, and the red light is a divergent light that has a condensing point at about 1400 mm on the lens entrance side. If a correction lens is provided at a position 100 mm after passing through the condenser lens 131, a concave lens 17 having a focal length of about 1300 mm may be used in the blue optical path, and a convex lens 16 having a focal length of about 1500 mm may be used in the red optical path.

Since the correction lens is applied to monochromatic light, the refractive index and the Abbe number of the material are not particularly problematic. If the glass material is BK7, the plastic material is polymethylmethacrylate (PMMA) or polycarbonate (PC). Low cost. Further, the lens is not limited to a spherical lens, and if a Fresnel lens is used, the optical system becomes compact.

Example 8. (Projection Display Device) In the projection display device of Example 7, the color separation means is configured by intersecting the two dichroic mirrors 14R and 14B, so that there is uneven brightness in the projected image due to the shadow of the intersection. There is a problem that occurs. In the eighth embodiment, the generation of shadows at the intersection can be reduced by using the linear emission lamp 120 and by setting the direction of the linear emission and the side direction of the intersection at a predetermined direction. The configuration will be described with reference to FIG. Reference numeral 120 denotes a linear light emitting lamp, which is a discharge lamp such as a metal halide lamp. Reference numeral 131 is a condenser lens for collimating the light emitted from the lamp 120, 14R and 14B are dichroic mirrors, and 3 is an image display device. Note that the figure shows the image display device 3 having only the optical path that transmits the dichroic mirrors 14B and 14R for simplification, and the image display device of other optical paths, the color synthesizing means, the projection lens and the like are omitted. Due to the electrode 121 set in the x direction, the line emission direction is also the x direction. By setting the intersections of the dichroic mirrors 14R and 14B in the y direction orthogonal to the electrodes, the shadow of the intersections can be reduced. The principle will be described with reference to FIG.

FIG. 34 (a) shows the electrode 12 in the x direction in FIG.
Set 1 to the intersection 14 of the dichroic mirrors 14R, 14B
C shows an xz sectional view in the case of being set in the y direction orthogonal to the direction of the electrode 121. The light emitted from the center A1 of the arc becomes a light flux A2 parallel to the z direction by the condenser lens 131, and a shadow A3 is generated by the joint portion. The light flux emitted from the electrode vicinity portion B1 becomes parallel light B2 which makes an angle with the z axis like B2, and a shadow like B3 is generated by the joint portion. Similarly, a light flux emitted from the vicinity C1 of the electrode produces a shadow like C3. However, since the respective illumination lights are superimposed on the respective shadows, the image display device 3 becomes a blurred shadow with low visibility.

FIG. 34B shows the electrode 12 in the y direction in FIG.
Xz when the direction of 1 is set and the intersection 14C of the dichroic mirrors 14R and 14B is in the same direction as the direction of the electrode 121.
FIG. In this cross-sectional view, the lamp 120 serves as a point-emission light emitting portion, and the light flux after passing through the condenser lens 131 is z.
Since only the component substantially parallel to the axis is included, the shadow of the intersection is clearly projected on the image display device 3. The uneven illumination on the image display device 3 appears as uneven brightness of the projected image.

Ninth Embodiment (Light Source Device) FIG. 35 is a diagram showing the structure of a light source device according to the ninth embodiment. The condenser lens 131 has a high temperature due to the radiant heat of the lamp 120. A glass material is generally used for the condenser lens 131. Condenser lens 13 because glass has low thermal conductivity
1 The entire surface does not have a uniform temperature, and the incident surface side has the highest temperature and the emission surface side has a lower temperature. Since the volume change due to thermal expansion differs between the incident surface side and the output surface side, the lens is distorted, and when the distortion limit is exceeded, the lens breaks and breaks. However, according to an experiment conducted by the present inventor, the condenser lens 131, which has been cracked once, absorbs the strain at the fracture surface, so that further cracking does not proceed. Therefore, the ninth embodiment is the condenser lens 13
By dividing 1 into two or more in advance, the splitting portion absorbs the strain caused by thermal expansion.

It is desirable that the division plane be parallel to the optical axis (one-dot chain line in FIG. 35). Since the light incident on the split surface is diffusely reflected, if the split surface is not parallel to the optical axis, the shadow thereof is likely to cause uneven illumination and uneven brightness on the projected image.

It is most effective to divide the lens at the thick portion of the lens where the difference in thermal expansion is the largest, that is, at the surface passing through the center of the lens. FIG. 35 shows an example of dividing into four, but any dividing line other than this, that is, dividing into two or three through the center may be used.

Embodiment 10. (Light Source Device) FIG. 36 is a diagram showing the structure of the light source device of Embodiment 10. Figure 36
In FIG. 10, the parts with the same numbers as in FIG. 10 indicate the same parts, and 131 is the condenser lens shown in the first or fourth embodiment. Reference numeral 145 is a filter for cutting the spectrum of unnecessary light in the luminous flux emitted from the lamp 120.

The operation of the tenth embodiment is similar to the operation of the above-described second embodiment, and the description thereof will be omitted.

In the tenth embodiment, as in the second embodiment, the surfaces S1 and S2 of the condenser lens 131 may be provided with a non-reflection coating, an ultraviolet / infrared light reflection coating, and an infrared light reflection coating, if necessary. In FIG. 36, a filter 145 made of an ultraviolet / infrared light reflecting coating or an infrared light reflecting coating is applied to the second surface S2 of the condenser lens 131 in FIG. Removing infrared rays (heat rays) from the surface of the condenser lens 131 on the light incident side is effective in preventing cracking of the condenser lens due to thermal influence. As described in the ninth embodiment, dividing the condenser lens 131 into a plurality of pieces is more effective in preventing cracking.

Example 11. (Polarizing Element) (Example 1) FIG. 37 is a configuration diagram of a polarizing element of Example 1 of Example 11. The polarizing element 62 has a shape in which columnar elements 162 each having a rhombic cross section are integrally connected at regular intervals, and the peaks (or valleys) of the incident side turn-back surface 63 and the peaks of the output side turn-back surface 64 (or The (valley) part is at the same position on the front and back. In addition,
The dashed-dotted line L in FIG. 37 (b) indicates the center line of the polarizing element 62, and N indicates the normal to the center line L. The inclination θi of the hypotenuse on the entrance surface 63 and the exit surface 64 of the polarizing element 62 forms an angle at which the P-polarized light is transmitted with low loss and a part of the S-polarized light is reflected. It should be noted that θ i is the angle in the direction normal to the plane of incidence / emission with respect to the normal N of the polarizing element 62. The exit surface has the same shape as the entrance surface, and when natural light 25 whose polarization direction is indefinite enters the polarizing element 62 in parallel with the normal line N, P-polarized light (FIG. 37) is generated.
In (b), most of the polarized light in the left-right direction on the paper surface is transmitted, but the S-polarized light (polarized light perpendicular to the paper surface) is partially reflected by the incident surface 63 and the exit surface 64. Therefore, the emitted light 26 becomes polarized light (partial polarized light) having a strong polarization component in the P direction.

The incident angle for transmitting 100% of P-polarized light is
As mentioned before, it is called Brewster's angle. Brewster angle θ at the interface between the air layer and the substrate layer having a refractive index n
B is calculated by the following equation (15). θi = θB = tan ^-1 n (15)

FIG. 38 shows the transmittance T and reflectance R of P-polarized light and S-polarized light with respect to the incident angle on the transparent substrate with n = 1.57.
When the incident angle θi is Brewster's angle θB = 57.51 °, P
About 100% of polarized light is transmitted, but about 18% of S-polarized light is reflected at the interface.

FIG. 39 is a diagram showing a light beam transmitted through a rhombus-shaped columnar element 162 which is a unit element of the polarizing element 62. To achieve Brewster's angle, the apex angle θP of the rhombus is set as in equation (16). θP = π-2θB (16) The luminous flux 25a incident on the diamond-shaped unit element 162 is the incident surface 63
After being refracted at the exit surface 64, it becomes an exit light beam 26a. The light beam 25b incident on the outer side of the light beam 25a passes through the unit element 162 like 26b and thus becomes unnecessary light 26b. The shaded area in the figure is an area ineffective as a polarizing element. If the rhombic unit elements 162 are connected and formed so that the shaded portions overlap each other, the optical loss due to the shaded portions can be eliminated.

Next, the optimum design of the cross-sectional shape of the polarizing element 62 shown in FIG. 37 (b) will be described. As shown in FIG. 40 (a), the maximum thickness from the center line L is a, the minimum thickness is b, the turn-around period of the incident surface is c, the refractive index of the material is n, and the Brewster angle obtained by the equation (15) is θB. Then, if there is a relation of the following expression (17), P-polarized light will pass through the element without loss. a: b: c = 1: 1 + 2 COS (2θB) :-( 4 / n) COS (2θB) (17) As an example when the above equation (17) is not satisfied, the thickness b is calculated from the equation (17). When it is small, a region that does not transmit light is generated as shown by the hatched portion in FIG. 40 (b), and a striped shadow is formed. Also, a light flux such as 25b becomes lost light.

In Example 1 above, the incident angle θi shown in FIG. 37 (b) was set so as to form the Brewster angle θB.
The larger i is a little larger than the Brewster angle, the larger the ratio of removing S-polarized light. FIG. 41 is a diagram showing the relationship of the transmission ratio (extinction ratio) of P-polarized light and S-polarized light with respect to the incident angle to the substrate of n = 1.57. For example, when the incident angle is 70 °, FIG.
As a result, the transmittance of P-polarized light is reduced by 4%, but the extinction ratio is improved by 15%. In this case, θP is the value 6 for Brewster's angle.
It will be changed from 4.98 ° to 40 °. Naturally, θP is 0
Since it is larger than °, θ in the range of 0 <θP ≤ π-2θB
Just set P.

The material of the polarizing element 62 may be any material that is transparent to the desired light wavelength. In the visible light region, there are glass materials and plastic materials. In terms of heat resistance, it is advantageous to mold or polish a glass material to prepare it. Plastic materials are advantageous in that complex shapes can be easily molded. Polymethyl methacrylate (PMMA), polystyrene (PS), polycarbonate (PC) and the like are plastic materials which are transparent in the visible light region and have a small absorption loss and excellent optical characteristics. If heat resistance is a problem when irradiating with a high brightness light source,
For example, the thermoplastic resin ARTON (manufactured by Japan Synthetic Rubber Co., Ltd.,
(Trade name), weighted deflection temperature 164 ° C.) and high heat resistant polycarbonate Apec HT (trade name, manufactured by Bayer, (trade name), weighted deflection temperature 141 to 215 ° C.).

The plastic material has a large absorption in the ultraviolet region, and when it is irradiated with high-intensity light containing a large amount of ultraviolet rays, it causes heat generation. Known ultraviolet / infrared cut filter is a polarizing element
By placing it on the lamp side of the incident surface 63 of 62, blocking the infrared light including the infrared light, and irradiating the polarizing element 62 with the natural light 25,
The temperature rise of the material can be reduced, and thermal deformation or modification of the polarizing element 62 can be prevented.

Further, the polarizing element may be forcibly cooled by air cooling or the like by using a known fan, and if the above-mentioned ultraviolet / infrared cut filter is used in combination, the cooling effect is further enhanced.

Example 2 FIG. 42 is a sectional view showing a polarizing element of Example 2 of Example 11. In the second example, three polarizing elements 62 shown in FIG. 37 (b) are laminated, and a ratio of removing an unnecessary polarized component (S polarized light) becomes large.

FIG. 43 shows P in the case where the natural light of Example 2 is incident.
It is the figure which represented the intensity ratio of polarization and S polarization by the extinction ratio and polarization degree. Since S-polarized light is removed from each of the incident surface and the output surface of one polarizing element 62, five elements (refractive index of substrate n = 1.57, incident angle θi = 57.51 °) shown in Example 1 should be laminated. For example, the intensity of S-polarized light is 15% or less of that of P-polarized light. The number of laminated layers may be appropriately set according to the application with reference to the extinction ratio in FIG.

When the thickness a of the optical element in Example 1 is set to 1 mm, the thickness b is 0.15 mm from the equation (17), and the layer thickness is 6.6 mm even if five elements are laminated. On the other hand, in FIG. 52 showing the conventional example, if the width of the liquid crystal light valve (or the width of the illumination light flux) is 40 mm, the depth D of the polarizing element 6 is 3
It is 0.8 mm or more, and it can be seen that the polarizing element of Example 2 can achieve a significant thinning. Moreover, the polarizing element of Example 2 does not change even if the width of the liquid crystal light valve (or the width of the illumination light flux) increases. On the other hand, in the conventional polarization element, the depth D of the polarization element increases in proportion to the width of the liquid crystal light valve (or the width of the illumination light beam).

Example 3 FIG. 44 is a sectional view showing Example 3 of Example 11, and FIG. 45 is a sectional view taken along line bb of FIG. Example 2
Similarly to the above, a plurality of polarizing elements 62 are laminated, but a spacer 65 is inserted at a position that does not obstruct the optical path to secure an air layer 66 between the polarizing elements 62. When the two polarizing elements 62 come close to each other, the separated S-polarized light undergoes multiple reflection between the polarizing elements 62 and becomes transmitted light again, so that the degree of polarization decreases. Furthermore, when the thickness of the air layer 66 reaches the wavelength order, it works as an interference film,
This causes a change in color of transmitted light and uneven color. As shown in FIG. 44, in order to prevent the S-polarized light 26s reflected on the incident surface 63b and separated from being reflected again on the output surface 64a, the polarizing element 62 of Example 2 is used.
If (design example of thickness a = 1 mm) is used, the gap d is 0.32
It suffices to insert the spacer 65 having a thickness of at least mm.

(Example 4) FIG. 46 is a sectional view showing Example 4 of Example 11, and FIG. 47 is a sectional view taken along line bb of FIG. Example 3
This is an example in which the spacer 65 is integrally molded with the polarizing element 62 by providing a protrusion 67 on a part of the polarizing element 62 instead of the spacer 65 used in. If a plastic material is used, it is relatively easy to integrally form the spacer.

In Examples 3 and 4, if the air layer 66 is used as an air passage to blow air by using a known fan or the like, there is also an effect that the polarizing element can be efficiently cooled.

Example 12 (Polarizing Element) FIG. 48 is a sectional view showing a polarizing element of Example 12. In the polarizing element 68, the peaks (or troughs) of the incident side turn-back surface 69 and the troughs (or peaks) of the exit side turn-back surface 70 are aligned on the front and back sides of the element. Therefore, the entire cross-sectional shape becomes a triangular wave shape, and the layer thickness is uniform, so that the structure has a strong mechanical strength. In order for the incident surface to form the Brewster angle θB, the turning angle θP between the incident surface 69 and the exit surface 70 is given by the following equation (18). θP = π-2θB (18)

The maximum thickness from the center is a, the minimum thickness is b,
When the folding period is c, when the following expression (19) is satisfied, P-polarized light passes through the polarizing element 68 without loss. a: b: c = 1: {2 + 3COS (2θB)} / {2 + COS (2θB)}:-{4COS (2θB)} / [n {2 + COS (2θB)}] ...... (19)

In addition, if the incident angle is set to be larger than Brewster's angle, the extinction ratio will be improved, and the material of the polarizing element 68 and examples of stacking it, spacers, etc.
This is similar to Examples 1, 2, 3, 4, and 11.

Example 13 (Projection Display Device) FIG. 49 is a diagram showing an optical system of a projection display device using the polarizing element in Example 13. If the polarizing elements 62 and 68 of the eleventh or twelfth exemplary embodiment or the polarizing element 16 in which a plurality of these are laminated are replaced by the polarizing element 6 of the conventional device (FIG. 51), the light source 120 is a liquid crystal light valve. Since the setting can be made close to, the device can be made compact, and the illuminance of the liquid crystal light valve can be increased, so that a high-luminance projection display device can be realized. 49 is different from FIG. 51 showing a conventional example only in that the polarization element 6 is changed, and other components and operations are the same, and therefore description thereof will be omitted. Further, the polarizing element 16 of FIG. 49 shows an example of a three-layer structure, but as the number of layers is increased, the extinction ratio (polarization degree) becomes better, and the incident side polarization plate 17r, of the liquid crystal light valves 3r, 3g, 3b. The heat generation of 17g and 17b can be reduced.

[0160]

As described in detail above, according to the first invention, a large-diameter condenser lens having the following excellent characteristics can be obtained. (A) It is possible to realize a highly efficient and low-aberration condenser lens having a large aperture of NA ≧ 0.9 and a small spherical aberration despite having a single lens configuration. (B) An irradiation light beam diameter larger than the focal length can be obtained. (C) A relatively long back focus can be secured on the second surface side compared to the focal length, and a sufficient working distance (WD) can be secured if the outside of the effective diameter of the second surface is a flat surface. Further, by making the outside of the effective diameter of the first surface a flat surface, a flange for holding the lens can be formed together with the flat surface on the second surface side.
Lens mounting becomes easy. (D) Since the peripheral portion of the second surface can be concave, the incident angle to the peripheral portion can be reduced and the transmittance can be improved. Further, when the surface of the light source side is coated with a multilayer film, the influence of the incident angle dependence of the transmission characteristics can be reduced. (E) Since it has a single lens structure, it is not necessary to consider decentering between lenses during mounting. Further, if the flange portion is integrally formed by a known glass molding method or the like, it can be mass-produced at low cost. (F) Since it has a single lens structure, the lens weight can be reduced,
Moreover, the absorption loss due to the lens material can be reduced. Further, the total lens length can be shortened as compared with the combined lens.

According to the second invention, the following effects can be obtained in addition to the effects (A) to (F) of the first invention described above. (G) Since a material having excellent heat resistance and a large Abbe number is used as the glass material, cracking can be prevented even when a high-power discharge lamp is used, and color unevenness of illumination light can be reduced.

According to the third invention, it is possible to realize a small and highly efficient light source device for illumination using the condenser lens of the first and second inventions. Moreover, since the condenser lens has a single lens structure, the light source device can be downsized, and the lens can be easily mounted by using the flange portion. Further, by setting the radius of curvature of the concave mirror constituting the light source device to be 1/2 or more of the effective diameter of the first surface of the condenser lens, the astigmatism of the illumination light can be reduced, and a sufficient margin for disposing the discharge lamp can be secured. . In addition, the first surface of the condenser lens is coated with a single layer of non-reflective coating, and the second surface is coated with infrared / ultraviolet reflective coating or infrared reflective coating, so that high transmittance can be achieved while removing unnecessary spectral components. Can be secured. Also, when using a DC driven xenon discharge lamp,
Since the focal point of the condenser lens and the center of curvature of the concave mirror are arranged at the cathode tip of the discharge lamp that serves as a point light source, the illumination light can be emitted parallel to the optical axis of the condenser lens.

Further, according to the fourth invention, since the light source device according to the third invention is applied to the liquid crystal projection display device, the liquid crystal panel can be illuminated with high illuminance and low aberration light. As a result,
A liquid crystal projection display device with high brightness and low power consumption can be realized. In addition, by aligning the electrode direction of the discharge lamp with the short side direction of the display screen of the liquid crystal panel and by setting the lamp posture around the electrodes so that the exhaust part of the burner faces the long side direction of the display screen, the brightness of the projected screen The unevenness can be reduced.

Further, according to the fifth aspect of the invention, a high-luminance projection display device excellent in color uniformity is realized by a light source device having a high utilization efficiency of a luminous flux emitted from a lamp by a single lens and a lens for correcting chromatic aberration. it can.

Further, according to the sixth invention, since the color separation means in which two dichroic mirrors are crossed is used,
Since the optical path length from the light source to the image display section is short, the projection display device has high brightness. By arranging the intersection of the linear light source and the dichroic mirror so as to be orthogonal to each other, the generation of shadows at the intersection is reduced, and a projection image with uniform brightness can be obtained.

Further, according to the seventh aspect of the invention, since the condenser lens is divided beforehand, the distortion of the lens due to the thermal expansion is absorbed by the dividing surface, so that cracking can be prevented.
Further, since the image is divided on a plane parallel to the optical axis, a shadow of the divided portion does not occur, and a projected image with uniform brightness can be obtained. further,
The effect is maximized by dividing along the line passing through the center of the lens where the difference in thermal expansion is the largest.

Further, according to the eighth aspect of the invention, since the incident surface side of the condenser lens is coated with a reflection of infrared light or infrared light and ultraviolet light, it is possible to remove the unnecessary light spectrum which causes heat. It is possible to reduce damage to the condenser lens due to thermal expansion. In addition, deterioration due to unnecessary spectrum of the liquid crystal panel can be minimized.

According to the ninth aspect of the invention, since the front surface and the back surface have a shape in which the P-polarized light is reflected back a plurality of times at an angle at which the P-polarized light is transmitted with low loss, the optical element for converting natural light into partially polarized light is thin. Furthermore, by setting the apex angle θP so that the incident angle and the outgoing angle of the polarizing element become Brewster's angle,
P-polarized light can be transmitted through the element interface without loss. Further, by designing the thickness of the element and the turn-back period to be optimum values by the equation (17), P-polarized light can be transmitted through the polarizing element without loss.
Further, by setting θP smaller than that of equation (16) in order to set the incident angle and the outgoing angle to the polarizing element to be larger than Brewster's angle, the extinction ratio can be improved although the transmittance of P-polarized light is slightly lowered. .

By using a plastic material as the material of the polarizing element, a complicated shape can be produced relatively easily and at a low cost as compared with a glass material or the like. When polarizing white light with high light intensity using a polarizing element made of a plastic material,
By using the infrared cut filter together, it is possible to reduce the deformation and modification of the polarizing element due to the temperature rise. Further, if forced cooling is performed by air cooling or the like, the effect of reducing the deformation or modification of the polarizing element is enhanced. In addition, since one polarizing element is thin, the polarizing element is thin even if a plurality of polarizing elements are laminated, and the extinction ratio can be improved as the number of layers is increased. Further, by inserting a spacer to secure an air layer between the elements, multiple reflection of S-polarized light between the elements can be removed, and the extinction ratio is improved. In addition, if the air layer is used as an air passage to cool by blowing air, thermal deformation of the polarizing element can be relaxed. Also, if the polarizing element and the spacer are integrally molded, the assembly process of the polarizing element can be reduced.

According to the tenth aspect of the invention, by making the cross section of the polarizing element into a triangular wave shape, the polarizing element has a uniform thickness and a strong mechanical strength. Further, by setting the incident angle and the outgoing angle of the polarizing element to Brewster's angle as in the ninth aspect, P-polarized light can be transmitted through the element interface without loss. Further, by designing the thickness of the element and the folding period to be optimum values, P-polarized light can be transmitted through the polarizing element without loss.

According to the eleventh invention, as an application example of the polarizing element of the ninth and tenth inventions, by applying it to a projection type display device using a liquid crystal light valve, a polarizing plate on the incident side of the liquid crystal light valve can be obtained. The heat generation is reduced, and the deterioration of the image quality due to the modification and deformation of the polarizing plate can be prevented. Further, since the polarizing element is thin, the light source can be installed close to the liquid crystal light valve, so that a projected image with high brightness can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of a condenser lens of the present invention.

FIG. 2 is a sectional view of a condenser lens of the present invention.

FIG. 3 is a spot diagram viewed from the small conjugate side of the condenser lens of the present invention.

FIG. 4 is an aberration diagram seen from the small conjugate side of the condenser lens of the present invention.

FIG. 5 is an aberration diagram of the condenser lens of the present invention viewed from the small conjugate side.

FIG. 6 is an aberration diagram seen from the small conjugate side of the condenser lens of the present invention.

FIG. 7 is an aberration diagram seen from the small conjugate side of the condenser lens of the present invention.

FIG. 8 is an aberration diagram of the condenser lens of the present invention as viewed on the small conjugate side.

FIG. 9 is an aberration diagram seen from the small conjugate side of the condenser lens of the present invention.

FIG. 10 is a diagram showing a configuration of a light source device of the present invention.

FIG. 11 is a diagram showing a configuration of a light source device of the present invention.

FIG. 12 is a diagram showing an example of a luminance distribution of a DC drive type xenon discharge lamp.

FIG. 13 is an explanatory diagram of light distribution characteristics of the discharge lamp.

FIG. 14 is a diagram showing an arrangement of a discharge lamp and a liquid crystal panel for reducing unevenness in brightness of a projected image.

FIG. 15 is a sectional view of a condenser lens of the present invention.

FIG. 16 is a spot diagram seen from the small conjugate side of the condenser lens of the present invention.

FIG. 17 is a sectional view of a condenser lens of the present invention.

FIG. 18 is a spot diagram seen from the small conjugate side of the condenser lens of the present invention.

FIG. 19 is a sectional view of a condenser lens of the present invention.

FIG. 20 is a spot diagram viewed from the small conjugate side of the condenser lens of the present invention.

FIG. 21 is a sectional view of the condenser lens of the present invention.

FIG. 22 is an aberration diagram seen from the smaller conjugate side of the condenser lens of the present invention.

FIG. 23 is an aberration diagram seen from the smaller conjugate side of the condenser lens of the present invention.

FIG. 24 is an aberration diagram seen from the smaller conjugate side of the condenser lens of the present invention.

FIG. 25 is an aberration diagram seen from the smaller conjugate side of the condenser lens of the present invention.

FIG. 26 is an aberration diagram seen from the smaller conjugate side of the condenser lens of the present invention.

FIG. 27 is an aberration diagram seen from the smaller conjugate side of the condenser lens of the present invention.

FIG. 28 is an aberration diagram seen from the smaller conjugate side of the condenser lens of the present invention.

FIG. 29 is an aberration diagram seen from the smaller conjugate side of the condenser lens of the present invention.

FIG. 30 is an aberration diagram seen from the smaller conjugate side of the condenser lens of the present invention.

FIG. 31 is a diagram showing a configuration of a light source device of the present invention.

FIG. 32 is a diagram showing a configuration of a projection display device of the present invention.

FIG. 33 is a diagram showing a configuration of a projection display device of the present invention.

FIG. 34 is a sectional view for explaining the projection display device of the present invention.

FIG. 35 is a diagram showing a configuration of a light source device of the present invention.

FIG. 36 is a diagram showing a configuration of a light source device of the present invention.

FIG. 37 is a diagram showing a configuration of a polarizing element of the present invention.

FIG. 38 is a graph showing a relationship between an incident angle on a transparent substrate, a transmittance and a reflectance.

FIG. 39 is an explanatory diagram of a light beam that passes through a columnar element that is a unit element of a polarizing element.

FIG. 40 is an explanatory diagram of a light flux that transmits a polarizing element.

FIG. 41 is a graph showing the relationship between the incident angle to the transparent substrate and the extinction ratio.

FIG. 42 is a cross-sectional view showing the structure of the polarizing element of the present invention.

FIG. 43 is a graph showing the relationship between the number of stacked polarizing elements and the degree of polarization.

FIG. 44 is a cross-sectional view showing the structure of the polarizing element of the present invention.

45 is a cross-sectional view taken along the line bb of FIG. 44.

FIG. 46 is a cross-sectional view showing the structure of the polarizing element of the present invention.

47 is a cross-sectional view taken along the line bb of FIG. 46.

FIG. 48 is a cross-sectional view showing the structure of the polarizing element of the present invention.

FIG. 49 is a diagram showing an optical system of the projection display apparatus of the present invention.

FIG. 50 is a diagram showing a configuration of a conventional projection display device.

FIG. 51 is a diagram showing the configuration of another conventional projection display device.

FIG. 52 is a diagram showing a conventional polarizing element.

[Explanation of symbols]

 1 Light source device 3 Image display device 4 Projection lens 14 Dichroic mirror 16 Convex lens 17 Concave lens 62 Polarizing element 65 Spacer 66 Air layer 67 Protrusion 68 Polarizing element 120 Discharge lamp 121 Electrode 123 Burner section 124 Discharge gap 130 Reflector 131 Condenser lens S1 No. 1st surface (large conjugate side surface) S2 2nd surface (small conjugate side surface)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (31) Priority claim number Japanese Patent Application No. 4-313261 (32) Priority date Hei 4 (1992) November 24 (33) Priority claim country Japan (JP)

Claims (33)

[Claims] 1. A double-sided aspherical single lens in which a first surface located on the large conjugate side is a convex surface and a peripheral portion of a second surface located on the small conjugate side is a concave surface, and the following conditions are satisfied: A condenser lens characterized by satisfying. 0.42 <r1 / nf <0.45 18 <| r2 / nf | -0.39 <K1 <-0.25 0.11 <△ 2 / f <0.14 where f: focal length of the entire lens system n: refractive index of lens r1: first surface Center curvature radius r2: Center curvature radius of the second surface K1: Conical constant of the first surface △ 2: Aspherical surface of the second surface in the periphery of the effective diameter and the reference spherical surface having the center curvature radius r2 in the optical axis direction Second by the difference
The direction in which the periphery of the surface bends to the smaller conjugate side is positive 2. A double-sided aspherical single lens having a convex first surface located on the large conjugate side and a concave peripheral surface on the second surface located on the small conjugate side. A condenser lens characterized by satisfying. 0.4 <r1 / nf <0.6 -0.5 <r2 / nf <-
0.3-0.6 <K1 <-0.2 -0.1 <SG2 / f <0.
1 However, f: focal length of the entire lens system n: refractive index of the lens r1: center radius of curvature of the first surface r2: center radius of curvature of the second surface K1: cone constant of the first surface SG2: effective of the second surface The difference in the optical axis direction with respect to the surface center of the aspherical surface at the outermost periphery of the diameter is the positive direction in which the second surface peripheral portion bends to the smaller conjugate side 3. A condenser lens according to claim 1, wherein the numerical aperture (NA) is 0.9 or more. 4. A flat surface orthogonal to the optical axis is formed in a portion having a diameter larger than the effective diameter of the second surface.
Alternatively, the condenser lens described in 2. 5. A flat surface orthogonal to the optical axis is formed on a portion having a diameter larger than the effective diameter of the first surface.
Alternatively, the condenser lens described in 2. 6. A discharge lamp, a spherical mirror, and the condenser lens according to claim 1 or 2, wherein a center of curvature of the spherical mirror and a focal point of the condenser lens on the second surface side are substantially common to each other. A light source device characterized in that the emission center of the discharge lamp is arranged at this common point. 7. The discharge lamp is a xenon discharge lamp having a pair of discharge electrodes composed of an anode and a cathode, and the discharge tip of the cathode of the xenon discharge lamp is arranged at the common point. The light source device according to claim 6. 8. The numerical aperture (NA) of the condenser lens
Is 0.9 or more, The claim 6 or 7 characterized by the above-mentioned.
The light source device described. 9. The first surface of the condenser lens is provided with a single-layer antireflection coating, and the second surface is provided with an infrared / ultraviolet reflection coating or an infrared reflection coating made of an optical multilayer film. The light source device according to claim 6, wherein: 10. The following relationship is satisfied when the radius of curvature of the spherical mirror is r and the diameter of the light beam emitted from the first surface of the condenser lens is D1. The light source device described. r ≧ D1 / 2 11. A pair of an image display device, a light source device for illuminating the image display device, and a projection lens for enlarging and projecting an image displayed on the image display device, wherein the light source device has a pair of discharge gaps. A discharge lamp having a discharge electrode and a burner enclosing the discharge gap, a spherical mirror, and the condenser lens according to claim 1 or 2, wherein the center of curvature of the spherical mirror and the focal point on the second surface side of the condenser lens. Is a common point, and the discharge gap of the discharge lamp is arranged at this common point. 12. The display screen of the image display device has a rectangular shape, and the discharge electrodes are arranged along the short side direction of the display screen.
The projection display device described. 13. A position around a discharge electrode of the discharge lamp is set so that an exhaust part provided in a part of a burner of the discharge lamp is aligned with a long side direction of a display screen of the image display device. 11. The method according to claim 11, wherein
The projection display device described. 14. A light source device composed of a lamp for emitting white light, a spherical mirror and a condenser lens, and a color separation means for separating white light emitted from the light source device into light of three primary colors of red, green and blue. And an image display device for forming images of the three primary colors of red, green, and blue, a color synthesizing unit for synthesizing images of the three primary colors of red, green, and blue, and a projection lens for enlarging and projecting the images. A projection display device characterized in that a concave lens or a convex lens is inserted in two optical paths of the primary color separated optical paths, and the intensity distribution of illumination light of the image display device is uniform. 15. A light source device composed of a line emission lamp for emitting white light, a spherical mirror and a condenser lens, and two dichroic mirrors intersecting each other,
A color separation unit that separates the white light into light of the three primary colors of red, green and blue, an image display device that forms an image of the three primary colors of red, green and blue, and an image of red, green and blue are synthesized. A projection display device comprising: a color synthesizing unit and a projection lens for enlarging and projecting an image, wherein a line emission direction of the lamp and a side direction of an intersection of the two filters are substantially orthogonal to each other. 16. A light source for emitting white light, a spherical mirror,
A light source device, comprising: a condenser lens, wherein the condenser lens is divided into two or more. 17. The light source device according to claim 16, wherein the condenser lens is divided in a cross section parallel to the optical axis. 18. The condenser lens is divided at a cross section passing through the center of the lens.
The light source device described. 19. A light source for emitting white light, a spherical mirror,
A light source device comprising a condenser lens, and an infrared light reflection coating or an infrared light / ultraviolet light reflection coating is applied to a light incident surface of the condenser lens. 20. A polarizing element for converting natural light whose polarization direction is indefinite into partial polarized light having a large polarization in only one direction,
The entrance surface and the exit surface are formed in a shape in which a plurality of diffraction elements are folded back at an angle such that P-polarized light is transmitted with low loss, and columnar unit elements having a rhomboidal cross section are connected at regular intervals. Characterizing polarizing element. 21. The incident angle and the outgoing angle θi are equal to each other to form the Brewster angle θB, and the pair of opposing apex angles θP of the diamond-shaped unit elements satisfy the following condition. The polarizing element described. θP = π-2θB where θB = tan ^-1 n n: refractive index of the polarizing element substrate 22. The polarizing element according to claim 20, wherein the relationship among the maximum thickness a from the center, the minimum thickness b, and the folding cycle c is set as follows. a: b: c = 1: 1 + 2 COS (2θB) :−( 4 / n) C
OS (2θB) 23. In order to set the incident angle and the outgoing angle θi to be greater than or equal to the Brewster angle θB, a pair of opposing apex angles θP of the diamond-shaped unit elements satisfy the following condition. The polarizing element described. 0 <θP ≤ π-2θB 24. In a polarizing element for converting natural light whose polarization direction is indefinite into partial polarization having large polarization in only one direction, a plurality of reflections are made at angles such that an incident surface and an outgoing surface transmit P polarized light with low loss. A polarizing element, characterized in that its cross section is formed in a triangular wave shape in which the positions of the peaks (valleys) of the incident surface and the troughs (peaks) of the outgoing surface coincide in the element plane. 25. The polarizing element according to claim 24, wherein the turning angle θ P satisfies the following condition. θP = π−2θB where θB = tan ⁻¹ n n: refractive index of the polarizing element substrate 26. The polarizing element according to claim 25, wherein the relationship among the maximum thickness a, the minimum thickness b, and the folding interval c from the center satisfies the following conditions. a: b: c = 1: {2 + 3COS (2θB)} / {2 + COS (2
θB)}:-{4COS (2θB)} / [n {2 + COS (2θ
B)}] 27. The polarizing element of claim 20, wherein the polarizing element is made of a plastic material.
The polarizing element described. 28. A polarized light source device comprising: the polarizing element according to claim 27; a light source that emits natural light; and an ultraviolet / infrared cut filter provided between the polarizing element and the light source. 29. A polarized light source device comprising: the polarizing element according to claim 27; a light source that emits natural light; and a fan that cools the polarizing element by blowing air. 30. The polarizing element according to claim 20, wherein a plurality of the polarizing elements are laminated. 31. The polarizing element according to claim 30, wherein a spacer is inserted between the polarizing elements laminated to form an air layer. 32. The projection structure serving as the spacer is integrally formed with the polarizing element.
1. The polarizing element according to 1. 33. In a projection display device for enlarging and projecting an image of a liquid crystal light valve illuminated by a light source on a screen by a projection lens, an incident surface and an emitting surface between the light source and the liquid crystal light valve transmit P-polarized light with low loss. A projection display device comprising a polarizing element having a shape in which a plurality of reflections are made at such angles.