Projection lens and projection type display apparatus using the same

The present invention relates to a projection lens that magnifies and projects display information and the like from a light bulb such as a liquid crystal display element, and more particularly to a projection lens suitable for a front-type projection type display device and a projection type display device using the same.

In recent years, projection type display devices using light bulbs such as liquid crystal display elements and DMD display elements have become widespread. In particular, three light bulbs are used to correspond to the illumination light of the RGB3 primary colors, the light modulated by each light bulb is combined with a prism, etc., and the image is displayed on the screen via the projection lens. Is widely used.

As described above, the projection lens mounted on the projection type display device of the type in which each modulated light from the three light bulbs is combined by the color synthesis optical system and projected is a prism or the like that performs color synthesis. A large back focus is required to place the lens and to avoid thermal problems. Further, in the color synthesis optical system, the spectral characteristics change depending on the angle of the incident light, so that the projection lens needs to have the characteristic that the entrance pupils seen from the reduction side are located sufficiently far away, that is, telecentricity. In addition, it is necessary to have a bright lens and to correct aberrations commensurate with the resolution of the light bulb.

As examples of those that satisfy such a requirement to some extent, those described in Patent Documents 1 and 2 below are known, for example. In addition, the applicant of the present application has already disclosed such a projection lens to the JPO (see Patent Document 3 below).

All of the lenses described in these patent documents are wide-angle lenses having an angle of view of 100 degrees or more.

<patcit num="1"><text>Japanese Patent Application Laid-Open No. 2003-015033</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 2004-326079</text></patcit><patcit num="3"><text>Japanese Patent Application No. 2007-157248</text></patcit>

<p num="0007"> By the way, as the projection type display device, a front type device in which the projection lens is arranged on the same side as the viewer with respect to the screen and the light emitted from the projection lens is imaged on the reflection type screen, and the projection lens and A rear-type device is known in which viewers are arranged so as to sandwich the screen and the light emitted from the projection lens is imaged on a transmissive screen.</p><p num="0008"> Of these, in the rear-projection display device, for example, like a rear projection television, the light source to the screen are housed in the cabinet, and the image is projected from the projection lens arranged on the back side toward the screen arranged on the front side of the cabinet. A well-known configuration is to project light carrying information. The above-mentioned Patent Documents 1 to 3 are also assumed to be mounted on such a rear-type projection display device.</p><p num="0009"> However, in such a rear-type projection lens, a prism or a mirror for folding back the optical axis is arranged in the lens system for the purpose of reducing the thickness of the cabinet, and the total length of the lens along the optical axis becomes long. Therefore, the spatial size of the device itself becomes large. Therefore, when the projection lens described in the above publication is used in a front-type projection display device, there is a problem that the size of the device cannot be reduced.</p><p num="0010"> Further, in the front type projection type display system (including the display device and the screen), the size of the installation space of the system is often limited as compared with the rear type display device. There is a demand for shortening the working distance from the screen to the screen, and a wide angle of view of the projection lens is required.</p><p num="0011"> The present invention has been made in view of such circumstances, and has a telecentric configuration on the reduction side, a configuration having a back focus suitable for a recent projection lens, and a projection related to a front-type projection display device. An object of the present invention is to provide a high-performance projection lens capable of achieving a compact and wide angle of view as a whole lens system so that it can be applied to a lens, and a projection type display device using such a projection lens. To do.</p>

<p num="0012"> The projection lens according to the present invention is A projection lens in which a first lens group having a negative refractive power and a second lens group having a positive refractive power are arranged in order from the enlargement side, and the reduction side is substantially telecentric. The first lens group has a first lens composed of an aspherical lens arranged on the most magnified side. The second lens group includes a second lens composed of a positive lens having an aperture inside or in the vicinity on the most magnified side, and also includes an aspherical lens. Two or more negative lenses and two or more joint surfaces are arranged between the diaphragm and the aspherical lens in the second lens group. It is characterized by satisfying the following conditional equations (1) and (2). 0.10 &lt;f / f_2-1&lt;0.30 (1) N_2-1&gt; 1.75 (2) here, f: Focal length of the entire lens system f_2-1: Focal length of the second lens N_2-1: Refractive index of the second lens with respect to the d line</p><p num="0013"> Further, among the lenses in the second lens group, it is preferable that the lenses other than the second lens and the aspherical lens satisfy any of the following conditional expressions (3) and (4). N2p &lt;1.55 (3) N2n&gt; 1.73 (4) here, N2p: Refractive index of the positive lens in the second lens group with respect to the d line N2n: Refractive index of the negative lens in the second lens group with respect to the d line</p><p num="0014"> In addition, the Abbe number (ν) is included in the second lens group._d) Is preferably 75 or more, and preferably includes two or more positive lenses.</p><p num="0015"> In addition, the first lens group includes an aspherical lens made of plastic, two negative meniscus lenses having a convex surface facing the magnifying side, a negative lens having a concave surface facing the magnifying side, and a reducing side in order from the magnifying side. It is preferable to arrange a bonded lens made of a positive lens with a convex surface facing.</p><p num="0016"> Further, it is preferable to move the bonded lens in the first lens group in the optical axis direction to perform focusing.</p><p num="0017"> Further, it is preferable that the bonded lens in the first lens group satisfies the following conditional expression (5). | N_1p-N_1n| &lt;0.1 (5) here, N_1p: The refractive index of the positive lens constituting the junction lens in the first lens group with respect to the d line. N_1n: The refractive index of the negative lens constituting the junction lens in the first lens group with respect to the d line.</p><p num="0018"> Further, the second lens group includes a positive lens, a bonded lens composed of a negative meniscus lens and a biconvex lens having a convex surface facing the magnified side, and a bonded lens composed of a biconcave lens and a biconvex lens, in order from the magnifying side. It is preferable that a spherical lens, a junction lens composed of a biconcave lens and a biconvex lens, and a biconvex lens are arranged.</p><p num="0019"> Further, the projection type display device according to the present invention includes a light source, a light valve, an illumination optical unit that guides a light flux from the light source to the light valve, and the projection lens according to the present invention. The light source is light-modulated by the light valve and projected onto a screen by the projection lens.</p>

<p num="0020"> Since the projection lens of the present invention has the above configuration, it has a back focus suitable for recent projection lenses and can be applied to a projection lens related to a front-type projection display device. It can be a high-resolution projection lens that can achieve compactness and wide angle of view as a whole.</p><p num="0021"> In particular, by configuring the conditional equations (1) and (2) to be satisfied at the same time, various aberrations such as spherical aberration and curvature of field are made good while achieving compactness of the lens system. be able to.</p><p num="0022"> Further, by using the projection lens of the present invention, the projection type display device of the present invention can be made compact so that it can be applied to the front type projection type display device.</p>

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a projection lens according to the present embodiment, and is a lens configuration diagram of the first embodiment described later. This lens will be described below as a representative of the present embodiment. In the figure, Z represents the optical axis.

The projection lens of this embodiment is the first lens group G having a negative refractive power in order from the magnifying side.₁And the second lens group G with positive refractive power₂And are arranged, and the reduction side is almost telecentric.

In addition, the first lens group G₁Is the first lens (first lens L) consisting of an aspherical lens on the most magnified side.₁) Is arranged. In addition, the second lens group G₂Is the second lens (the sixth lens L in each embodiment) consisting of a positive lens on the most magnified side.₆), And the aperture S is arranged inside or near the positive lens. In addition, the second lens group G₂Is equipped with an aspherical lens.

Also, aperture S and second lens group G₂Two or more negative lenses and two or more joint surfaces are arranged between the aspherical lens inside (in the example below, two negative lenses except those in Example 6 are arranged. It has two joint surfaces, and the one in Example 6 has two negative lenses and three joint surfaces).

In addition, the above first lens group G₁More specifically, from the magnifying side, the first lens L made of an aspherical lens made of plastic₁And the second lens L consisting of a negative meniscus lens with a convex surface facing the magnifying side₂And the third lens L₃And the 4th lens L consisting of a negative lens with a concave surface facing the magnifying side₄And the fifth lens L consisting of a positive lens with a convex surface facing the reduction side₅, It is preferable that the bonded lens is arranged in an array.

In addition, the above first lens group G₁It is preferable to move the bonded lens inside in the Z direction of the optical axis for focusing.

On the other hand, the above second lens group G₂More specifically, the sixth lens L consisting of a positive lens in order from the magnifying side.₆And the 7th lens L consisting of a negative meniscus lens with a convex surface facing the magnifying side₇And the 8th lens L consisting of a biconvex lens₈And the 9th lens L consisting of both concave lenses₉And the 10th lens L consisting of a biconvex lens₁₀And the 11th lens L consisting of an aspherical lens₁₁And the 12th lens L consisting of both concave lenses₁₂And the 13th lens L consisting of a biconvex lens₁₃And the 14th lens L consisting of a biconvex lens₁₄And are preferably arranged. This second lens group G₂In the above, as shown in the following examples, a plurality of bonded lenses are provided, which can improve the correction of spherical aberration and chromatic aberration and improve the manufacturing efficiency of the lens. it can.

In addition, the above second lens group G₂Inside, Abbe number (ν_d) Includes two or more positive lenses with a value of 75 or more (in the example below, the 13th lens L₁₃And the 14th lens L₁₄2 positive lenses are applicable).

In the projection lens of FIG. 1, a luminous flux incident from the right side of the paper surface and given image information on the image display surface 1 of the light valve is incident on the projection lens via a color synthesis prism (including various filters) 2. , This projection lens is designed to magnify and project to the left side of the paper surface. In FIG. 1, only one image display surface 1 is shown for ease of viewing. However, in the projection type display device, the luminous flux from the light source is separated into three primary color lights by a color separation optical system, and each primary color is shown. It is possible to display a full-color image by arranging three light valves for light.

Further, the one of the present embodiment is configured to satisfy the following conditional equations (1) and (2). 0.10 &lt;f / f_2-1&lt;0.30 (1) N_2-1&gt; 1.75 (2) here, f: Focal length of the entire lens system f_2-1: 2nd lens (6th lens L in the example)₆) Focal length N_2-1: 2nd lens (6th lens L in the example)₆), Refractive index with respect to the d line

Further, among the lenses of the second lens group, the lens of the present embodiment is the second lens (the sixth lens L in the following embodiment).₆) And the aspherical lens (11th lens L in the example below)₁₁), It is preferable that all the lenses satisfy any of the following conditional expressions (3) and (4). N_2p&lt;1.55 (3) N_2n&gt; 1.73 (4) here, N_2p: 2nd lens group G₂Refractive index of the positive lens inside with respect to the d line N_2n: 2nd lens group G₂Refractive index of the negative lens inside with respect to the d line

In addition, the above first lens group G₁The bonded lens inside preferably satisfies the following conditional equation (5). | N_1p-N_1n| &lt;0.1 (5) here, N_1p: 1st lens group G₁Refractive index of the positive lens that constitutes the above-mentioned junction lens inside with respect to the d line N_1n: 1st lens group G₁Refractive index of the negative lens that constitutes the above-mentioned junction lens inside with respect to the d line

By satisfying at least (1) and (2) of the above conditional expressions, the above-mentioned effects of the present invention can be obtained.

Hereinafter, the significance of each of the above conditional expressions (1) to (5) will be described.

The conditional expression (1) is the second lens (the sixth lens L in the embodiment).₆) Indicates the range of values of the focal length f of the entire system with respect to the focal length. Below this lower limit, the entire lens system becomes larger, which is contrary to the demand for compactness, while above the upper limit makes it difficult to correct spherical aberration.

The effect of the conditional expression (1) can be further improved by configuring the conditional expression (1 ́) so as to satisfy the following conditional expression (1 ́) instead of the conditional expression (1). 0.15 &lt;f / f_2-1&lt;0.25 (1 ́)

The conditional expression (2) is based on the above-mentioned second lens (the sixth lens L in the embodiment).₆), Which defines the lower limit of the refractive index for the d-line. Below this lower limit, it becomes difficult to correct spherical aberration and curvature of field.

Next, the conditional expression (3) is the second lens group G.₂It defines the upper limit of the refractive index of the positive lens inside with respect to the d line, while the conditional expression (4) defines the second lens group G.₂It defines the lower limit of the refractive index of the negative lens inside with respect to the d line. If neither the conditional equation (3) nor the conditional equation (4) is satisfied, it becomes difficult to correct spherical aberration and axial / magnification chromatic aberration.

By replacing the above conditional equation (4) with a configuration that satisfies the following conditional equation (4 ́), the correction of spherical aberration and axial / magnification chromatic aberration should be improved. Can be done. N_2n&gt;1.75 (4 ́)

Conditional expression (5) is the first lens group G₁Refractive index N with respect to the d-line of the positive lens constituting the above-mentioned junction lens inside_1pAnd the first lens group G₁Refractive index N with respect to the d line of the negative lens constituting the above-mentioned junction lens inside_1nIt defines the range of the absolute value of the difference from. That is, the condition is that the difference in the refractive index of the materials forming the two lenses constituting this bonded lens is as small as less than 0.1. If it is out of this range, the fluctuation of the image plane at the time of focus adjustment becomes large.

In addition, the first lens group G₁And the second lens group G₂The shape of each aspherical surface included in is defined by the aspherical surface formula shown below. In these aspherical lenses, the effect can be obtained even when one of the surfaces is aspherical, but it is more preferable that both sides are aspherical.

<maths num="1"><img id="000002" he="55" wi="150" file="JP5259353B2_D0001.tif" img-format="tif" img-content="drawing" /></maths>

Next, an embodiment of the projection type display device according to the present invention will be described. FIG. 17 is a schematic view showing a projection type display device according to an embodiment of the present invention.

As shown in FIG. 17, the illumination optical system 10 includes transmissive liquid crystal panels 11a to 11c as light valves, dichroic mirrors 12 and 13 for color separation, a cross dichroic prism 14 for color synthesis, and a condenser. It is equipped with lenses 16a to 16c and total reflection mirrors 18a to 18c. Although not shown in the front stage of the dichroic mirror 12, a white light source is arranged, and the white light from this light source is divided into three color light beams (G light, B light, and R light) via the illumination optics section. They are incident on the corresponding liquid crystal panels 11a to 11c, light-modulated, and projected onto the screen 7 by the projection lens shown in FIG.

Hereinafter, specific examples of the projection lens according to the present invention will be described. In each of the embodiments, the members having the same configurations and the same effects are designated by the same reference numerals.

&lt;Example 1&gt; As shown in FIG. 1, the projection lens according to the first embodiment has a first lens group G having a negative refractive power in order from the magnifying side.₁And the second lens group G with positive refractive power₂And are arranged, and the reduction side is almost telecentric.

In addition, the first lens group G₁Is the first lens group G₁Is the first lens L made of an aspherical lens with a small refractive power in order from the magnifying side.₁And the second lens L consisting of a negative meniscus lens with a concave surface facing the reduction side₂And the third lens L₃And the 4th lens L consisting of both concave lenses₄And the fifth lens L consisting of a biconvex lens₅Two lenses are arranged.

On the other hand, the second lens group G₂Is a sixth lens L consisting of a plano-convex lens with a diaphragm 3 arranged inside and a convex surface facing the magnifying side.₆And the 7th lens L consisting of a negative meniscus lens with a concave surface facing the reduction side₇And the 8th lens L consisting of a biconvex lens₈And the 9th lens L consisting of both concave lenses₉And the 10th lens L consisting of a biconvex lens₁₀And the 11th lens L consisting of an aspherical lens with a small refractive power₁₁And the 12th lens L consisting of both concave lenses₁₂And the 13th lens L consisting of a biconvex lens₁₃And the 14th lens L₁₄Are arranged.

The second lens group G₂In, 7th lens L₇And the 8th lens L₈, And 9th lens L₉And the 10th lens L₁₀Are joined to each other to form a two-element bonded lens.

This projection lens is configured to be telecentric on the reduction side.

In addition, the first lens group G₁Inside, 4th lens L₄And the 5th lens L₅It is configured to perform focusing by moving the junction lens formed by joining the lenses in the Z direction of the optical axis.

The projection lens according to the first embodiment is configured to satisfy all of the above conditional expressions (1) to (5), (1 ́), and (4 ́).

Further, FIG. 1 shows an image display surface 1 of the light bulb and a color synthesis prism (including various filters) 2.

The numerical values of the focal length f (mm), back focus Bf (mm), F number Fno., And angle of view 2ω of the entire system in Example 1 are shown at the top of Table 1.

Further, the radius of curvature R (mm) of each lens surface of the projection lens according to the first embodiment, the center thickness of each lens, the air spacing between each lens (hereinafter referred to as "axis upper surface spacing") D (mm), and each lens. Refractive index N on the d line of_dAnd the Abbe number ν on the d-line of each lens_dThe values of are shown in the upper part of Table 1. In Table 1 and the following tables, the numbers of the surface numbers indicate the order from the enlarged side, and the surfaces marked with * on the left side of the surface numbers are aspherical surfaces. In Example 1 and Examples 2 to 8 below, the radius of curvature R of these aspherical surfaces is shown as the value of the radius of curvature R on the optical axis Z in each table, but in the corresponding lens configuration diagram, it is shown. In order to make the drawing easier to see, some leader lines are not always drawn from the intersection with the optical axis Z.

In addition, in the middle of Table 1, the surface spacing D when focusing at a predetermined projection distance (1.2 m, infinity)₁, D₂The numerical value of is shown. In the lower part of Table 1, each constant K, A corresponding to each aspherical surface is shown.₃~ A₁₂The value of is shown.

<tables num="1"><img id="000003" he="236" wi="150" file="JP5259353B2_D0001.tif" img-format="tif" img-content="drawing" /></tables>

The values corresponding to the conditional expressions (1) to (5), (1 ́), and (4 ́) in the first embodiment are as shown in Table 9 described later, and the conditional expressions (1) to (5) are shown. ), (1 ́), (4 ́) are all satisfied.

&lt;Example 2&gt; The configuration of the projection lens according to the second embodiment is as shown in FIG. 2, which is basically the same as the projection lens according to the first embodiment, but the aperture S is the sixth lens L.₆In that it is arranged on the reduction side more than the reduction side surface of the 6th lens L₆However, it differs from the projection lens according to the first embodiment in that it is a positive meniscus lens with a convex surface facing the magnifying side.

The numerical values of the focal length f (mm), back focus Bf (mm), F number Fno., And angle of view 2ω of the entire system in Example 2 are shown at the top of Table 2. Further, the radius of curvature R (mm) of each lens surface of the projection lens according to the second embodiment, the axis top surface distance D (mm), and the refractive index N in the d line of each lens._dAnd the Abbe number ν on the d-line of each lens_dThe values of are shown in the upper part of Table 2.

In the middle of Table 2, the surface spacing D when focusing at a predetermined projection distance (1.2 m, infinity)₁, D₂The numerical value of is shown. In the lower part of Table 2, each constant K, A corresponding to each aspherical surface is shown.₃~ A₁₂The value of is shown.

<tables num="2"><img id="000004" he="234" wi="150" file="JP5259353B2_D0001.tif" img-format="tif" img-content="drawing" /></tables>

The values corresponding to the conditional expressions (1) to (5), (1 ́), and (4 ́) in the second embodiment are as shown in Table 9 described later, and the conditional expressions (1) to (5) are shown. ), (1 ́), (4 ́) are all satisfied.

&lt;Example 3&gt; The configuration of the projection lens according to the third embodiment is as shown in FIG. 3, and is basically the same as the projection lens according to the first embodiment, but the sixth lens L₆Is different from the projection lens according to the first embodiment in that is a biconvex lens.

The numerical values of the focal length f (mm), back focus Bf (mm), F number Fno., And angle of view 2ω of the entire system in Example 3 are shown at the top of Table 3. Further, the radius of curvature R (mm) of each lens surface of the projection lens according to the third embodiment, the axial top surface distance D (mm), and the refractive index N in the d line of each lens._dAnd the Abbe number ν on the d-line of each lens_dThe values of are shown in the upper part of Table 3.

In the middle of Table 3, the surface spacing D when focusing at a predetermined projection distance (1.2 m, infinity)₁, D₂The numerical value of is shown. In the lower part of Table 3, each constant K, A corresponding to each aspherical surface is shown.₃~ A₁₆The value of is shown.

<tables num="3"><img id="000005" he="245" wi="148" file="JP5259353B2_D0001.tif" img-format="tif" img-content="drawing" /></tables>

The values corresponding to the conditional expressions (1) to (5), (1 ́), and (4 ́) in the third embodiment are as shown in Table 9 described later, and the conditional expressions (1) to (5) are shown. ), (1 ́), (4 ́) are all satisfied.

&lt;Example 4&gt; The configuration of the projection lens according to the fourth embodiment is as shown in FIG. 4, and is basically the same as the projection lens according to the first embodiment, but the sixth lens L₆Is a biconvex lens, and the 7th lens L₇Is a single lens and the 8th lens L₈, 9th lens L₉And the 10th lens L₁₀Is different from the projection lens according to the first embodiment in that the lenses are sequentially bonded to form a three-element bonded lens.

The numerical values of the focal length f (mm), back focus Bf (mm), F number Fno., And angle of view 2ω of the entire system in Example 4 are shown at the top of Table 4. Further, the radius of curvature R (mm) of each lens surface of the projection lens according to the fourth embodiment, the axial top surface distance D (mm), and the refractive index N in the d line of each lens._dAnd the Abbe number ν on the d-line of each lens_dThe values of are shown in the upper part of Table 4.

In addition, in the middle of Table 4, the surface spacing D when focusing at a predetermined projection distance (1.2 m, infinity)₁, D₂The numerical value of is shown. In the lower part of Table 4, each constant K, A corresponding to each aspherical surface is shown.₃~ A₁₆The value of is shown.

<tables num="4"><img id="000006" he="245" wi="148" file="JP5259353B2_D0001.tif" img-format="tif" img-content="drawing" /></tables>

The values corresponding to the conditional expressions (1) to (5), (1 ́), and (4 ́) in the fourth embodiment are as shown in Table 9 described later, and the conditional expressions (1) to (5) are shown. ), (1 ́), (4 ́) are all satisfied.

&lt;Example 5&gt; The configuration of the projection lens according to the fifth embodiment is as shown in FIG. 5, and is basically the same as the projection lens according to the first embodiment, but the sixth lens L₆Is a biconvex lens, and the 7th lens L₇, 8th lens L₈And 9th lens L₉Are sequentially joined to form a three-element joining lens, and the tenth lens L₁₀Is different from the projection lens according to the first embodiment in that is a single lens.

The numerical values of the focal length f (mm), back focus Bf (mm), F number Fno., And angle of view 2ω of the entire system in Example 5 are shown at the top of Table 5. Further, the radius of curvature R (mm) of each lens surface of the projection lens according to the fifth embodiment, the axial top surface distance D (mm), and the refractive index N in the d line of each lens._dAnd the Abbe number ν on the d-line of each lens_dThe values of are shown in the upper part of Table 5.

In the middle of Table 5, the surface spacing D when focusing at a predetermined projection distance (1.2 m, infinity)₁, D₂The numerical value of is shown. In the lower part of Table 5, each constant K, A corresponding to each aspherical surface is shown.₃~ A₁₆The value of is shown.

<tables num="5"><img id="000007" he="245" wi="148" file="JP5259353B2_D0001.tif" img-format="tif" img-content="drawing" /></tables>

The values corresponding to the conditional expressions (1) to (5), (1 ́), and (4 ́) in the fifth embodiment are as shown in Table 9 described later, and the conditional expressions (1) to (5) are shown. ), (1 ́), (4 ́) are all satisfied.

&lt;Example 6&gt; The configuration of the projection lens according to the sixth embodiment is as shown in FIG. 6, which is basically the same as the projection lens according to the first embodiment, but the sixth lens L.₆Is a biconvex lens, and the 7th lens L₇, 8th lens L₈, 9th lens L₉And the 10th lens L₁₀Is different from the projection lens according to the first embodiment in that the lenses are sequentially joined to form a four-element bonded lens.

The numerical values of the focal length f (mm), back focus Bf (mm), F number Fno., And angle of view 2ω of the entire system in Example 6 are shown at the top of Table 6. Further, the radius of curvature R (mm) of each lens surface of the projection lens according to the sixth embodiment, the axial top surface distance D (mm), and the refractive index N in the d line of each lens._dAnd the Abbe number ν on the d-line of each lens_dThe values of are shown in the upper part of Table 6.

In addition, in the middle of Table 6, the surface spacing D when focusing at a predetermined projection distance (1.2 m, infinity)₁, D₂The numerical value of is shown. In the lower part of Table 6, each constant K, A corresponding to each aspherical surface is shown.₃~ A₁₆The value of is shown.

<tables num="6"><img id="000008" he="245" wi="150" file="JP5259353B2_D0001.tif" img-format="tif" img-content="drawing" /></tables>

The values corresponding to the conditional expressions (1) to (5), (1 ́), and (4 ́) in the sixth embodiment are as shown in Table 9 described later, and the conditional expressions (1) to (5) are shown. ), (1 ́), (4 ́) are all satisfied.

&lt;Example 7&gt; The configuration of the projection lens according to the seventh embodiment is as shown in FIG. 7, and is basically the same as the projection lens according to the first embodiment, but the sixth lens L₆Is different from the projection lens according to the first embodiment in that is a biconvex lens.

The numerical values of the focal length f (mm), back focus Bf (mm), F number Fno., And angle of view 2ω of the entire system in Example 7 are shown at the top of Table 7. Further, the radius of curvature R (mm) of each lens surface of the projection lens according to the seventh embodiment, the axial top surface distance D (mm), and the refractive index N in the d line of each lens._dAnd the Abbe number ν on the d-line of each lens_dThe values of are shown in the upper part of Table 7.

In the middle of Table 7, the surface spacing D when focusing at a predetermined projection distance (1.2 m, infinity)₁, D₂The numerical value of is shown. In the lower part of Table 7, each constant K, A corresponding to each aspherical surface is shown.₃~ A₁₆The value of is shown.

<tables num="7"><img id="000009" he="245" wi="148" file="JP5259353B2_D0001.tif" img-format="tif" img-content="drawing" /></tables>

The values corresponding to the conditional expressions (1) to (5), (1 ́), and (4 ́) in the seventh embodiment are as shown in Table 9 described later, and the conditional expressions (1) to (5) are shown. ), (1 ́), (4 ́) are all satisfied.

&lt;Example 8&gt; The configuration of the projection lens according to the eighth embodiment is as shown in FIG. 8, which is basically the same as the projection lens according to the first embodiment, but the sixth lens L.₆Is different from the projection lens according to the first embodiment in that is a biconvex lens.

The numerical values of the focal length f (mm), back focus Bf (mm), F number Fno., And angle of view 2ω of the entire system in Example 8 are shown at the top of Table 8. Further, the radius of curvature R (mm) of each lens surface of the projection lens according to the eighth embodiment, the axial top surface distance D (mm), and the refractive index N in the d line of each lens._dAnd the Abbe number ν on the d-line of each lens_dThe values of are shown in the upper part of Table 8.

In addition, in the middle of Table 8, the surface spacing D when focusing at a predetermined projection distance (1.2 m, infinity)₁, D₂The numerical value of is shown. In the lower part of Table 8, each constant K, A corresponding to each aspherical surface is shown.₃~ A₁₆The value of is shown.

<tables num="8"><img id="000010" he="245" wi="148" file="JP5259353B2_D0001.tif" img-format="tif" img-content="drawing" /></tables>

The values corresponding to the conditional expressions (1) to (5), (1 ́), and (4 ́) in the eighth embodiment are as shown in Table 9 described later, and the conditional expressions (1) to (5) are shown. ), (1 ́), (4 ́) are all satisfied.

Further, FIGS. 9 to 16 are aberration diagrams showing various aberrations (spherical aberration, astigmatism, distortion and chromatic aberration of magnification) of the projection lens according to the first to eighth embodiments. In these aberration diagrams, ω indicates a half angle, the aberration diagram of spherical aberration shows the aberration curves for light with wavelengths of 550 nm, 460 nm and 620 nm, and the aberration diagram of chromatic aberration of magnification shows the aberration curve for light with wavelength of 550 nm. The aberration curves at 460 nm and 620 nm light are shown. As shown in FIGS. 9 to 16, in the projection lenses according to Examples 1 to 8, each aberration such as distortion and chromatic aberration of magnification is satisfactorily corrected, and the half angle of view is 50.7 degrees or more and the F number is 2.00 to 2.30, which is a wide angle. It is said to be a bright projection lens. It also has sufficient back focus (29.52 ~ 30.31). Furthermore, each conditional expression is satisfied, and it is considered as a compact and high-performance projection lens.

The projection lens of the present invention is not limited to that of the above embodiment, and various modes can be changed. For example, the radius of curvature R and the lens spacing (or lens thickness) D of each lens are appropriately changed. It is possible to do.

Further, the projection type display device of the present invention is not limited to the above configuration, and various device configurations including the projection lens of the present invention are possible. Examples of the light valve include a transmissive or reflective liquid crystal display element and a micromirror element in which a large number of micromirrors capable of changing the tilt are formed on a substantially flat surface (for example, manufactured by Texas Instruments). Digital micromirror device) can be used. Further, as the illumination optical system, an appropriate configuration corresponding to the type of the light bulb can be adopted.

<tables num="9"><img id="000011" he="58" wi="159" file="JP5259353B2_D0001.tif" img-format="tif" img-content="drawing" /></tables>

<figref num="1">The figure which shows the structure of the projection lens which concerns on Example 1 of this invention.</figref><figref num="2">The figure which shows the structure of the projection lens which concerns on Example 2 of this invention.</figref><figref num="3">The figure which shows the structure of the projection lens which concerns on Example 3 of this invention.</figref><figref num="4">The figure which shows the structure of the projection lens which concerns on Example 4 of this invention.</figref><figref num="5">The figure which shows the structure of the projection lens which concerns on Example 5 of this invention.</figref><figref num="6">The figure which shows the structure of the projection lens which concerns on Example 6 of this invention.</figref><figref num="7">The figure which shows the structure of the projection lens which concerns on Example 7 of this invention.</figref><figref num="8">The figure which shows the structure of the projection lens which concerns on Example 8 of this invention.</figref><figref num="9">Aberration diagram of the projection lens according to the first embodiment</figref><figref num="10">Aberration diagram of the projection lens according to the second embodiment</figref><figref num="11">Aberration diagram of the projection lens according to the third embodiment</figref><figref num="12">Aberration diagram of the projection lens according to the fourth embodiment</figref><figref num="13">Aberration diagram of the projection lens according to the fifth embodiment</figref><figref num="14">Aberration diagram of the projection lens according to the sixth embodiment</figref><figref num="15">Aberration diagram of the projection lens according to the seventh embodiment</figref><figref num="16">Aberration diagram of the projection lens according to the eighth embodiment</figref><figref num="17">The figure which shows the schematic structure of the projection type display device of this invention.</figref>

Code description

1 Image display surface Two-color composite prism 11a ~ 11c Transmissive LCD panel 12, 13 Dichroic mirror 14 Cross dichroic prism 16a ~ 16c condenser lens 18a ~ 18c Total reflection mirror G₁, G₂ Lens group L₁~ L₁₄ lens R₁~ R₂₇ Radius of curvature of the lens surface, etc. D₁~ D₂₆ Lens center thickness and air spacing between lenses (shaft top spacing) S aperture Z optical axis