JP5275902B2 - Wide angle lens for projection and projection display device - Google Patents

Abstract

The utility model discloses a wide-angle lens for projection, which is sequentially provided with a first lends group G1 with negative refraction, a second lens group G2 with positive refraction and a third lens group G3 with positive refraction from a magnification side. The first lens group G1 consists of three negative lenses (a first lens L1 to a third lens L3), and the second lens group G2 consists of an adhesive lens mutually adhered by a fourth lens L4 and a fifth lens L5 sequentially from the magnification side. In addition, the third lens group G3 consists of five single lenses (a ninth lens L9 to a thirteenth lens L13) respectively having positive refraction, negative refraction, positive refraction, negative refraction and positive refraction sequentially from the magnification side, and a grating position is arranged inside the third lens group G3. Accordingly, the wide-angle lens for projection combines wide-angle with miniaturization, and can maintain fine optical performance even under use environment when temperature close to the grating position is very high.

Description

  The present invention relates to a wide-angle lens for projection used as a projection lens for a projector apparatus or the like, and particularly for projection suitable for enlarging and projecting an original image formed by a light beam modulated by a micromirror device on a screen. The present invention relates to a wide-angle lens and a projection display device equipped with the same.

  In recent years, a so-called front projection type projector device that projects an image on a screen in front of the device has been widely used for school education, company training, presentation, and the like.

  The projection lens installed in such a projector apparatus has a narrow indoor space in order to prevent light from entering the eyes of an instructor or presenter standing near the screen or blocking the projection image by them. In order to enable a large screen, a wide angle of view is required while having a compact configuration.

  In addition, as a light modulation element (light valve) mounted on a projector device, a transmissive or reflective liquid crystal display element has been well known in the past. However, in recent years, it is advantageous for downsizing and high luminance. For these reasons, a micromirror device represented by a digital micromirror device (DMD) manufactured by Texas Instruments is often used as a light valve.

  A projector device using a micromirror device is generally a telecentric type using a TIR prism. However, the TIR prism is expensive, or the TIR prism reduces the amount of illumination light and the brightness of the image. In recent years, the non-telecentric type has been attracting attention for reasons such as the reduction of the level of noise.

  In this non-telecentric method, projection is performed with the micro mirror device side (reduction side) made non-telecentric in order to efficiently guide the necessary light from the micro mirror device to the projection lens and prevent unnecessary light from entering the projection lens. In addition to using a lens, a shift arrangement is adopted in which the center position of the micromirror device is shifted with respect to the optical axis of the projection lens.

  By adopting such a shift arrangement, the projection lens used in the non-telecentric system needs to make the image circle considerably larger than the size of the micromirror device. For this reason, the lens size on the reduction side, which is non-telecentric, can be reduced, but the lens size on the screen side tends to be large, and the angle of view is more than 85 degrees, preferably more than 100 degrees. It is difficult to achieve downsizing at the same time.

  Conventionally, as a projection lens used in a non-telecentric system, for example, a lens that achieves an angle of view of 94 degrees described in Patent Document 1 has been proposed.

JP 2006-215476 A

  When the projection lens used in the non-telecentric system is to have a wide angle, it is more difficult to suppress the curvature of field than in the telecentric system. In order to suppress the curvature of field, it is effective to use a cemented lens having a concave surface with a large curvature and reduce the Petzval sum while suppressing the influence on other aberrations. On the other hand, when the curvature of the cemented surface is increased, the lens diameter is also increased. Therefore, when downsizing is required, it is necessary to sufficiently consider the arrangement position of such a cemented lens.

  The projection lens described in the above-mentioned Patent Document 1 reduces the size of the projection lens by disposing a cemented lens in the vicinity of the stop position where the beam diameter is reduced in the lens system, and reduces the Petzval sum to reduce the curvature of field. While suppressing, other aberrations such as chromatic aberration are corrected.

  However, the diaphragm position is the position where the light source image of the illumination light is formed, and the energy density of the light is high and the temperature is high. Therefore, placing a cemented lens in the vicinity of the diaphragm position is the durability of the adhesive on the cemented surface. Considering that there is a risk of damaging the reliability of the projection lens and the reliability of maintaining the performance of the projection lens, this is not preferable.

  The present invention has been made in view of such circumstances, and can achieve both wide-angle and downsizing and maintain good optical performance even in a use environment in which the vicinity of the aperture position becomes extremely high temperature. An object of the present invention is to provide a projection wide-angle lens that can be used, and a projection display device equipped with such a projection wide-angle lens.

In order to achieve the above object, a wide-angle lens for projection according to the present invention has, in order from the magnification side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a positive refractive power. A wide-angle lens for projection, which is composed of a third lens group, projects a light beam modulated by a micromirror device arranged on the reduction side to the enlargement side, and the reduction side is non-telecentric,
The first lens group includes three negative lenses,
The second lens group includes a cemented lens in which a positive lens and a negative lens are cemented with each other in order from the magnification side,
The third lens group includes, in order from the magnification side, positive, negative, positive, Ri Do negative, five of the single lens having positive refractive power, respectively,
Located aperture in said third lens group is characterized that you have been set.

  Preferably, at least one of the three negative lenses in the first lens group is made of a resin aspheric lens.

  The three negative lenses of the first lens group are, in order from the magnification side, a first lens made of a resin aspheric lens and a second lens made of a negative meniscus lens having a convex surface facing the magnification side. And a third lens, and the first lens preferably has a smaller refractive power than the second lens and the third lens.

  Further, the second lens group includes, in order from the magnifying side, a first mode including a two-lens cemented lens in which a positive lens and a negative lens are cemented with each other and a positive lens, or sequentially from the magnifying side, a positive lens, A second mode including a three-piece cemented lens in which a negative lens and a positive lens are cemented with each other, or a first cemented lens, a negative lens, and a positive lens in which a positive lens and a negative lens are cemented with each other in order from the magnification side. It is preferable that the lens is configured in any one of the third aspects including the second cemented lens that is cemented with each other.

Further, when the Abbe numbers of the magnifying side lens and the reducing side lens cemented with each other on the cementing surface located on the most magnifying side of the second lens group are ν _L and ν _S respectively, the following conditional expression (1) is satisfied: It is preferable to satisfy.
| Ν _S −ν _L | <23.0 (1)

  A projection display device according to the present invention includes a light source, a micromirror device, an illumination optical unit that guides a light beam from the light source to the micromirror device, and the projection wide-angle lens according to the present invention. The light beam from the light source is optically modulated by the micromirror device and projected onto a screen by the wide-angle lens for projection.

  The “enlarged side” means the projected side (screen side), and the screen side is also referred to as the enlarged side for the sake of convenience when performing reduced projection. On the other hand, the “reduction side” means the original image display area side (light valve (micromirror device) side), and the light valve side is also referred to as the reduction side for the sake of convenience when performing reduced projection.

  The “aperture position” means a position where the principal rays intersect with each other (imaging position of the light source).

  The above-mentioned “micromirror device” means a light modulation element in which a large number of micromirrors capable of changing the tilt are arranged in parallel, for example, a digital micromirror device manufactured by Texas Instruments ( DMD) corresponds to this.

  In order to achieve the above object, the wide-angle lens for projection according to the present invention is configured so that the three lens groups have negative, positive, and positive refractive powers in order from the magnification side, and the reduction side is made non-telecentric. The first lens group is composed of three negative lenses, and the third lens group is composed of five single lenses each having positive, negative, positive, negative, and positive refractive power in order from the magnification side. Yes.

  With this configuration, it is possible to reduce the size while achieving a wide angle of view of 85 degrees or more, and maintain good optical performance even in a use environment where the vicinity of the aperture position becomes extremely high. A wide-angle lens for projection that can be used, and a projection display device equipped with the same can be obtained.

  In particular, the third lens group is composed of five single lenses each having positive, negative, positive, negative, and positive refractive power in order from the magnification side, so that spherical aberration, chromatic aberration, and field curvature can be reduced. It is possible to maintain good optical performance even in a use environment in which the vicinity of the aperture position becomes extremely high temperature while correcting well.

1 is a detailed configuration diagram of a wide-angle lens for projection according to Embodiment 1. FIG. FIG. 3 is a configuration diagram illustrating a ray trajectory of the wide-angle lens for projection according to the first embodiment. 6 is a detailed configuration diagram of a wide-angle lens for projection according to Embodiment 2. FIG. FIG. 6 is a configuration diagram illustrating a ray locus of a wide-angle lens for projection according to a second embodiment. 6 is a detailed configuration diagram of a wide-angle lens for projection according to Embodiment 3. FIG. FIG. 10 is a configuration diagram illustrating a light ray locus of a wide-angle lens for projection according to a third embodiment. 6 is a detailed configuration diagram of a wide-angle lens for projection according to Embodiment 4. FIG. FIG. 10 is a configuration diagram illustrating a light ray locus of a wide-angle lens for projection according to a fourth embodiment. FIG. 3 is a diagram illustrating various aberrations of the wide-angle lens for projection according to the first example. FIG. 6 is a diagram illustrating various aberrations of the wide-angle lens for projection according to Example 2. FIG. 6 is a diagram illustrating various aberrations of the wide-angle lens for projection according to Example 3. FIG. 10 is a diagram illustrating all aberrations of the wide-angle lens for projection according to Example 4; It is a schematic block diagram of the projection type display apparatus which concerns on one Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the above-mentioned drawings. Hereinafter, this lens will be described as a representative of the present embodiment with reference to FIG. 1 which is a lens configuration diagram of Example 1 described later. In the figure, Z represents the optical axis.

Projection wide-angle lens of the embodiment comprises, in order from the enlargement side (the screen side), a first lens group G ₁ having a negative refractive power, a second lens group G ₂ having a positive refractive power, positive refractive The first lens group G ₁ includes three negative lenses (first lens L ₁ to third lens L ₃ ), and the third lens group G _{3 includes a} third lens group G ₃ having power. G ₃ is composed of five single lenses (9th lens L ₉ to 13th lens L ₁₃ ) having positive, negative, positive, negative, and positive refractive power in order from the enlargement side.

  In the wide-angle lens for projection according to this embodiment, a light beam given image information on the image display surface 1 of the micromirror device arranged on the reduction side is incident from the reduction side (right side in the figure) through the cover glass 2. The projection wide-angle lens enlarges and projects on a screen arranged on the enlargement side (left side in the figure). The wide-angle lens for projection according to the present embodiment is non-telecentric on the reduction side so that it can be used in a non-telecentric system. In FIG. 1, the center position of the image display surface 1 of the micromirror device is drawn so as to coincide with the optical axis Z of the wide-angle lens for projection, but when actually used, the wide-angle lens for projection is drawn. The center position of the image display surface 1 of the micromirror device is arranged so as to shift in a predetermined direction (for example, downward in the figure) with respect to the optical axis Z (see FIG. 13).

In the projection wide-angle lens of the present embodiment, the second lens group G ₂ includes a positive lens from the enlargement side in order (fourth lens L ₄₎ and a negative lens (the fifth lens L ₅₎ are bonded to each other is configured to include a cemented lens, to the third in the lens group G _3, throttle position is set.

By thus configuring the second lens group G _2, (aperture) stop while reducing the influence of the aberrations affect the position, by the joint surfaces, appropriate differences in influence the axial and the screen around By using this, it is possible to satisfactorily correct the curvature of field. The diaphragm position (the principal rays intersect each other position), by setting the third in the lens group G _3, which is composed only a single lens, disposed cemented lens in the vicinity of the aperture position become hot during use In this case, there is no problem of the durability of the adhesive on the joint surface, which is a concern, so that good optical performance can be maintained.

In the wide-angle lens for projection according to the present embodiment, the three negative lenses of the first lens group G ₁ are arranged in order from the enlargement side to the first lens L ₁ made of a resin aspheric lens and to the enlargement side. The second lens L ₂ is composed of a negative meniscus lens having a convex surface and a third lens L _3. The first lens L ₁ is refracted more than the second lens L ₂ and the third lens L _3. The absolute value of the force (in the case of an aspheric lens, the refractive power in the paraxial region) is assumed to be small.

Thus, by constituting the first lens group G _1, despite the wide field angle, distortion, curvature of field, the aberration particularly affected by the angle of view of such astigmatism is favorably corrected Is possible.

Further, the projection angle lens of the present embodiment, the second lens group G ₂ includes, in order from the enlargement side, a positive lens (the fourth lens L ₄₎ and a negative lens (the fifth lens L ₅₎ are bonded to each other Two cemented lenses and a positive lens (in this embodiment, two positive lenses (the sixth lens L ₆ and the eighth lens L ₈ ), but can be one or more than three positive lenses) However, in place of such a first aspect, as shown in FIG. 5, a positive lens (fourth lens L ₄ ), a negative lens ( The fifth lens L ₅ ) and the positive lens (sixth lens L ₆ ) have a second aspect including a cemented three-lens, and as shown in FIG. positive lens (the fourth lens _{L 4)} and a negative lens (the fifth lens L ) Is a third embodiment comprising a second cemented lens in which the first cemented lens and a negative lens (the sixth lens L ₆₎ and a positive lens (seventh lens L ₇₎ are joined to one another which are joined to one another It is also possible.

Thus, the second lens group G _2, by configuring the first aspect to the third aspect described above, in addition to the effects described above, the bonding surface using a cemented triplet and two cemented lenses By increasing the number of, the effect on the on-axis and the periphery of the screen due to the joint surface is properly utilized while reducing the effect on the aberration affected by the (aperture) aperture position, and the image It is possible to further correct the surface curvature.

In the wide-angle lens for projection according to the present embodiment, the enlargement side lens (fourth lens L ₄ ) and the reduction side lens (fifth lens) which are cemented with each other on the cementing surface located closest to the magnification side of the second lens group G ₂ . When the Abbe numbers of the lens L ₅ ) are ν _L and ν _S , respectively, the following conditional expression (1) is satisfied. More preferably, the following conditional expression (1A) or the following conditional expression (1B) is satisfied.
| Ν _S −ν _L | <23.0 (1)
10 <| ν _S −ν _L | <23.0 (1A)
10 <ν _S −ν _L <23.0 (1B)

  With this configuration, various aberrations can be favorably corrected while avoiding an excessive influence on the chromatic aberration due to the joint surface.

  Next, an embodiment of a projection display apparatus according to the present invention will be described with reference to FIG. The projection display device shown in FIG. 13 includes an illumination system 20 and a micromirror device 11 as a light valve that optically modulates a light beam from the illumination system 20, and relates to the above-described embodiment as the projection wide-angle lens 10. A wide-angle lens for projection is used.

  The illumination system 20 includes an illumination lamp 21 having a white light source 21a and an ellipsoidal mirror 21b, a color wheel 22, a rod integrator 23, an illumination lens 24, and a reflection mirror 25. The light beam from 21 is selectively converted into each color light of the three primary colors (R, G, B) in time series by the color wheel 23, and the light quantity distribution in the cross section perpendicular to the optical axis of the light beam is made uniform by the rod integrator 23. After that, the minute mirror device 11 is irradiated through the illumination lens 24 and the reflection mirror 25.

  The light beam applied to the micromirror device 11 is incident on the projection wide-angle lens 10 after being optically modulated in accordance with image information in the micromirror device 11 and projected onto the screen 31 by the projection wide-angle lens 10. It has become.

In addition, the projection display apparatus of the present embodiment employs a non-telecentric method, and is arranged so that the center position of the micromirror device 11 is shifted downward in the drawing with respect to the optical axis of the wide-angle lens 10 for projection. ing. Due to such an arrangement, the projection wide-angle lens 10 requires an image circle 12 that is considerably larger than the size of the micromirror device 11. The light beam modulated by the micromirror device 11 is emitted obliquely upward and to the left in the figure through the projection wide-angle lens 10, and forms a projection screen at a position higher than the optical axis Z (upward position in the figure). The projection screen center position P ₀ , the projection screen upper end position P ₁ , and the projection screen lower end position P ₂ are shown on the screen 31, respectively. Note that a light beam Q indicated by a broken line in FIG. 13 is a light beam having an emission angle corresponding to the corner of the projection screen, and is illustrated for convenience in order to show a relative relationship with the optical axis Z.

  The projection display apparatus according to the present embodiment achieves an angle of view of 85 degrees or more (100 degrees or more in a preferred embodiment) while having a compact configuration by using the projection wide-angle lens according to the above-described embodiment. However, since stable optical performance can be maintained, the portability and usability of the apparatus can be improved.

  Specific examples of the wide-angle lens for projection according to the present invention will be described below. 3 to 8 showing the configurations of the embodiments 2 to 4, the members having the same functions and effects as those of the embodiment 1 are denoted by the same reference numerals as those used in FIGS.

<Example 1>
As shown in FIGS. 1 and 2, the projection lens according to Example 1, in order from the magnification side, a first lens group G ₁ having a negative refractive power, a second lens group having a positive refractive power G ₂ and a third lens group G ₃ having a positive refractive power, and the first lens group G ₁ is composed of three negative lenses (first lens L ₁ to third lens L ₃ ). configured, the third lens group G ₃ includes, in order from the magnification side, positive, negative, positive, negative, by five of the single lens having positive refractive power, respectively (ninth lens L _{9 ~} thirteenth lens L ₁₃₎ It is configured. Also, to allow use of a non-telecentric system, the reduction side are the non-telecentric, on the reduction side of the third lens group G _3, the image display surface 1 and the cover glass 2 of the micro-mirror device, reduction Arranged in this order from the side.

The first lens group G ₁ includes, in order from the magnification side, a first lens L ₁ made of a double-sided aspherical resin lens having a weak negative refractive power in the paraxial region, and a negative lens with a convex surface facing the magnification side. The second lens L ₂ is a meniscus lens, and the third lens L ₃ is a negative meniscus lens having a concave surface facing the enlargement side. The first lens L ₁ includes the second lens L ₂ and the second lens L ₂ . than third lens L ₃ are as power is small.

The second lens group G ₂ includes, in order from the magnification side, a cemented doublet lens fifth lens L _5, which is a fourth lens L ₄ and a biconcave lens of a biconvex lens are bonded to each other, a biconvex lens 6 a lens L _6, the seventh lens L ₇ formed of a negative meniscus lens having a concave surface facing the magnification side, and a eighth lens L ₈ Metropolitan formed of a biconvex lens.

The third lens group G ₃ includes, in order from the magnification side, a ninth lens L _{9 made} of a biconvex lens, a tenth lens L _{10 made} of a biconcave lens, an eleventh lens L _{11 made} of a biconvex lens, and a magnification side. a twelfth lens L ₁₂ convex of a negative meniscus lens with a, is composed of a thirteenth lens L ₁₃ Metropolitan a biconvex lens, the diaphragm position is set to ₃ the third lens group G.

The shape of each aspheric surface in the first lens L ₁ is defined by the following aspheric expression. In the first lens L ₁ , an aberration correction effect can be obtained even if any one of the surfaces is an aspherical surface, but a lens having both aspherical surfaces is more preferable ( also each aspherical shape of the first lens L ₁ of examples 2-4 of the same below).

The curvature radius R (mm) of each lens surface of the wide-angle lens for projection according to Example 1, the center thickness of each lens, and the air space between each lens (hereinafter referred to as “axial upper surface space”) D (mm), each lens Table 1 shows the effective diameter (mm), the refractive index N _d of each lens at the d-line, and the Abbe number ν _d of each lens at the d-line. In Table 1 and Tables 2 to 4 below, the numbers of the surface numbers represent the order from the enlargement side, and the surface marked with * on the right side of the surface number is an aspherical surface. In Example 1 and Examples 2 to 4 below, the curvature radius R of these aspheric surfaces is shown as the value of the curvature radius on the optical axis Z in each table. In order to make it easier to see, some leader lines are not necessarily drawn from the intersection with the optical axis Z.

In the lower part of Table 1, the values of the constants K, A _{3 to} A ₁₂ corresponding to the respective aspheric surfaces are shown.

As shown in Table 1, the difference [nu ₅ -v ₄ the Abbe number [nu ₅ Abbe number [nu ₄ and the fifth lens L ₅ of the fourth lens L ₄ of the projection lens according to Example 1 is 16.2 . ν ₄ and ν ₅ correspond to the above-described ν _L and ν _S , and the projection wide-angle lens according to Example 1 satisfies all of the conditional expressions (1), (1A), and (1B) described above. Yes.

  The ratio of the effective diameter (63.99mm) of the lens surface closest to the enlargement side to the effective diameter (13.98mm) of the lens surface closest to the reduction side is 4.577 (≒ 63.99 / 13.98), which is 5 times or less. As well as widening (angle of view 101.7 degrees), it has achieved miniaturization.

<Example 2>
As shown in FIGS. 3 and 4, the wide-angle lens for projection according to the second embodiment has the same configuration as the wide-angle lens for projection according to the first embodiment.

The curvature radius R (mm) of each lens surface of the projection wide-angle lens according to Example 2, the axial top surface distance D (mm), the effective diameter of each lens (mm), the refractive index N _d of each lens at the d-line, and each The value of the Abbe number ν _d at the d-line of the lens is shown in the upper part of Table 2.

In the lower part of Table 2, the values of the constants K, A _{3 to} A ₁₂ corresponding to the respective aspheric surfaces are shown.

As shown in Table 2, the difference [nu ₅ -v ₄ the Abbe number [nu ₅ Abbe number [nu ₄ and the fifth lens L ₅ of the fourth lens L ₄ of the projection lens according to Example 2 is 12.8 . ν ₄ and ν ₅ correspond to the above-described ν _L and ν _S , and the projection wide-angle lens according to Example 2 satisfies all the conditional expressions (1), (1A), and (1B). Yes.

  The ratio of the effective diameter (66.04mm) of the lens surface closest to the enlargement side to the effective diameter (14.64mm) of the lens surface closest to the reduction side is 4.511 (≒ 66.04 / 14.64), which is 5 times or less. As well as widening (angle of view 101.2 degrees), it has achieved miniaturization.

<Example 3>
As shown in FIGS. 5 and 6, the wide-angle lens for projection according to Example 3 has the same configuration as the wide-angle lens for projection according to Example 1. However, the second lens group G ₂ includes, in order from the enlargement side, the fourth lens L ₄ is a biconvex _lens, the sixth lens L ₆ made of the fifth lens L ₅ and a biconvex lens of a biconcave lens are bonded together 3 a single cemented lens, a seventh lens L ₇ formed of a negative meniscus lens having a concave surface facing the magnification side, is different in that it is composed of the eighth lens L ₈ Metropolitan formed of a biconvex lens.

The radius of curvature R (mm) of each lens surface of the wide-angle lens for projection according to Example 3, the axial distance D (mm), the effective diameter of each lens (mm), the refractive index N _d of each lens at the d-line, and each The value of the Abbe number ν _d at the d-line of the lens is shown in the upper part of Table 3.

In the lower part of Table 3, values of constants K, A _{3 to} A ₁₂ corresponding to the respective aspheric surfaces are shown.

As shown in Table 3, the difference [nu ₅ -v ₄ the Abbe number [nu ₅ the Abbe number [nu ₄ of the fourth lens L ₄ of the projection lens according to Example 3 the fifth lens L ₅ is 18.2 . ν ₄ and ν ₅ correspond to the above-described ν _L and ν _S , and the wide-angle lens for projection according to Example 3 satisfies all the conditional expressions (1), (1A), and (1B) described above. Yes.

  The ratio of the effective diameter (60.03mm) of the lens surface located closest to the enlargement side to the effective diameter (13.96mm) of the lens surface closest to the reduction side is 4.300 (≒ 60.03 / 13.96), which is 5 times or less. As well as widening (angle of view 102.0 degrees), it has achieved miniaturization.

<Example 4>
As shown in FIGS. 7 and 8, the wide-angle lens for projection according to the fourth embodiment has the same configuration as the wide-angle lens for projection according to the first embodiment. However, the second lens group G ₂ includes, in order from the enlargement side, a first cemented lens fifth lens L _5, which is a fourth lens L ₄ and a biconcave lens of a biconvex lens are joined together, a convex surface on the enlargement side a negative second cemented lens the sixth lens L ₆ and the seventh lens L ₇ made of a biconvex lens are bonded to each other consisting of a meniscus lens directing, the eighth lens L ₈ made of a biconcave lens, a biconvex lens It is different in that it is composed of 9 lens L ₉ Prefecture.

The third lens group G ₃ has been the same structure as a projection lens according to Example 1, since the second lens group G ₂ is composed of six lenses, third number of lenses constituting the lens group G ₃ is shifted by one. That is, the third lens group G ₃ of the projection lens according to Example 4 includes, in order from the magnification side, a tenth lens L ₁₀ made of a biconvex lens, an eleventh lens L ₁₁ of a biconcave lens, a biconvex lens a twelfth lens L ₁₂ becomes, a thirteenth lens L ₁₃ of a negative meniscus lens having a convex surface facing the magnification side, and a fourteenth lens L ₁₄ Metropolitan formed of a biconvex lens.

The curvature radius R (mm) of each lens surface of the projection wide-angle lens according to Example 4, the axial top surface distance D (mm), the effective diameter of each lens (mm), the refractive index N _d of each lens at the d-line, and each The value of the Abbe number ν _d at the d-line of the lens is shown in the upper part of Table 4.

The lower part of Table 4 shows values of constants K, A _{3 to} A ₁₂ corresponding to the respective aspheric surfaces.

As shown in Table 4, the difference [nu ₅ -v ₄ the Abbe number [nu ₅ Abbe number [nu ₄ and the fifth lens L ₅ of the fourth lens L ₄ of the projection lens according to Example 4 is 22.6 . ν ₄ and ν ₅ correspond to the above-described ν _L and ν _S , and the wide-angle lens for projection according to Example 4 satisfies all the conditional expressions (1), (1A), and (1B) described above. Yes.

  The ratio of the effective diameter (70.00mm) of the lens surface closest to the enlargement side to the effective diameter (14.01mm) of the lens surface closest to the reduction side is 5.96 (≒ 70.00 / 14.01), which is 5 times or less. As well as widening (angle of view 101.8 degrees), it has achieved miniaturization.

  9 to 12 are aberration diagrams showing various aberrations (spherical aberration, distortion, astigmatism, and lateral chromatic aberration) of the wide-angle lens for projection according to Examples 1 to 4. FIG. In these aberration diagrams, ω represents a half angle of view, the aberration diagram for spherical aberration represents the aberration curve for each wavelength of G (green), B (blue), and R (red), and the aberration diagram for magnification chromatic aberration. Shows aberration curves of B and R with respect to G. As shown in FIGS. 9 to 12, the wide-angle lens for projection according to Examples 1 to 4 is well corrected for each aberration including distortion and lateral chromatic aberration, and has an angle of view of 101.2 to 102.0 degrees, an F number of 2.5, and a wide angle. It is a bright projection lens.

  The wide-angle lens for projection according to the present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the radius of curvature R and the axial distance D between the lenses can be appropriately changed. Is possible.

  Further, the projection display device of the present invention is not limited to the above-described configuration, and various device configurations including the projection wide-angle lens of the present invention are possible.

1 image display surface 2 the cover glass 10 for projection angle lens 11 micro-mirror device 12 the image circle 20 illumination system 21 illuminating lamp 21a white light source 21b ellipsoidal mirror 22 color wheel 23 the rod integrator 24 illuminate the lens 25 a reflection mirror Z optical axis G ₁ ~ G ₃ lens group L _{1 to} L ₁₄ lenses R _{1 to} R ₂₈ Curvature radii such as lens surfaces D _{1 to} D ₂₈ axis upper surface spacing P ₀ projection screen center position P ₁ projection screen upper position P ₂ projection screen lower position Q (projection Rays (with exit angles corresponding to the corners of the screen)

Claims (6)

In order from the magnification side, the first lens group having negative refractive power, the second lens group having positive refractive power, and the third lens group having positive refractive power are arranged on the reduction side. A projection wide-angle lens that projects a light beam modulated by a micromirror device on the enlargement side, and the reduction side is non-telecentric,
The first lens group includes three negative lenses,
The second lens group includes, in order from the magnification side, a cemented lens in which a positive lens and a negative lens are cemented with each other.
The third lens group includes, in order from the magnification side, positive, negative, positive, Ri Do negative, five of the single lens having positive refractive power, respectively,
The third lens aperture located in the group is set, projection wide-angle lens, characterized in that. Wherein at least one of the three negative lenses of the first lens group, a projection wide-angle lens according to claim 1, characterized in that an aspherical lens made of resin. The three negative lenses of the first lens group are, in order from the magnification side, a first lens composed of an aspheric lens made of resin, and a second lens composed of a negative meniscus lens having a convex surface facing the magnification side, and a third lens, the first lens, projection wide-angle lens according to claim 1, wherein the absolute value of the refractive power than the second lens and third lens is small. The second lens group includes a first lens unit including a two-lens cemented lens in which a positive lens and a negative lens are cemented with each other in order from the magnification side, and a positive lens, or a positive lens, a negative lens, and a lens in order from the magnification side. In the second mode including the three-lens cemented lens in which the positive lenses are cemented with each other, or the first cemented lens in which the positive lens and the negative lens are cemented together, and the negative lens and the positive lens are cemented in order from the enlargement side. The wide-angle lens for projection according to any one of claims 1 to 3 , wherein the projection wide-angle lens is configured in any one of the third aspects including the second cemented lens. The following conditional expression (1) is satisfied, where ν _L and ν _S are the Abbe numbers of the magnifying side lens and the reducing side lens that are cemented with each other on the cementing surface located on the most magnifying side of the second lens group, respectively. The wide-angle lens for projection according to claim 4 .
| Ν _S −ν _L | <23.0 (1) A light source, a micromirror device, an illumination optical unit that guides a light flux from the light source to the micromirror device, and the projection wide-angle lens according to any one of claims 1 to 5 , A projection display device, wherein a light beam is optically modulated by the micromirror device and projected onto a screen by the wide-angle lens for projection.

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