JP5006113B2 - Wide angle zoom lens for projection and projection display device - Google Patents

Description

  The present invention relates to a zoom lens used as a projection lens for a projector apparatus or the like, and particularly enlarges and projects an original image formed by a light valve such as a liquid crystal display element or a DMD (digital micromirror device) on a screen. The present invention relates to a projection wide-angle zoom lens suitable for use in a projector, 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 mounted on such a front projection type projector device has a zooming function or a compact size considering the portability of the device and the compatibility with installation conditions. It is required to have a wide angle of view while having a simple structure.
Conventionally, as projection zoom lenses that meet such demands, for example, those described in Patent Documents 1 and 2 below have been proposed.

JP 2003-15038 A JP 2005-292260 A

  In the above-mentioned Patent Documents 1 and 2, the half angle of view at the wide-angle end is less than 45 degrees, but in recent years, the half angle of view at the wide-angle end is 45 degrees while maintaining good optical performance ( There is a demand for a wide-angle zoom lens for projection that is preferably at least 50 degrees.

  In a fixed-magnification projection lens mounted on a rear projection apparatus or the like, there is known a projection lens having a half angle of view of 45 degrees or more. However, in the case of a zoom lens, when trying to achieve a half field angle of 45 degrees or more, It is difficult to maintain good optical performance from the wide-angle end to the telephoto end. In particular, axial aberrations such as spherical aberration common to the angle of view (image height) and distortion (distortion aberration) and images that change according to the angle of view. While balancing with off-axis aberrations such as surface curvature, it is difficult to correct both of them well. Further, there has been a problem that the lens system of the lens group arranged on the magnifying side becomes large and it is difficult to make it compact, and this has not been realized.

  The present invention has been made in view of such circumstances, and achieves a half angle of view of 45 degrees or more at the wide-angle end while maintaining good optical performance, and can achieve a compact wide angle for projection. An object of the present invention is to provide a zoom lens and a projection display device equipped with the zoom lens.

  In order to achieve the above object, in the wide-angle zoom lens for projection according to the present invention, in the focusing lens group arranged on the magnifying side, at least four negative lenses are continuously arranged from the magnifying side, and the largest magnification among them. An aspheric lens is provided on the side and the most reduction side.

  That is, the wide-angle zoom lens for projection according to the present invention, in order from the magnifying side, is a focusing lens group that is fixed at the time of zooming and has a negative refractive power, and moves independently from each other at the time of zooming. A wide-angle zoom lens for projection in which a plurality of zooming moving lens groups and a pupil position fixing lens group having a positive refractive power that is fixed at the time of zooming are arranged, and the focusing lens group includes: It comprises at least four negative lenses arranged continuously from the most magnified side, and among the at least four negative lenses, the most magnified negative lens and the most demagnified negative lens are each magnified side At least one of the reduction-side lens surfaces is aspherical.

In the wide angle zoom lens for projection according to the present invention, when the focal length of the entire system at the wide angle end is Fw, the back focus is Bf, and the focal length of the focusing lens group is Ff, the following conditional expression (1 ) And (2) are preferably satisfied.
2.5 <Bf / Fw (1)
1.5 <| Ff | / Fw <2.0 (2)

  The projection display device according to the present invention includes a light source, a light valve, an illumination optical unit that guides a light beam from the light source to the light valve, the wide-angle zoom lens for projection, and the reduction side is telecentric. And a projection wide-angle zoom lens. The light beam from the light source is modulated by the light valve and projected onto a screen by the projection wide-angle zoom lens.

  The “negative lens” means a lens having negative refractive power at least in the paraxial region.

  According to the wide-angle zoom lens for projection according to the present invention, since it has the above-described configuration, in particular, in the focusing lens group arranged on the enlargement side, at least four negative lenses are continuous from the most enlargement side. With this configuration, it is possible to suppress the enlargement of the focusing lens group while achieving a wide angle of 45 degrees or more at the wide angle end, and it is also possible to achieve a compact overall size. It becomes.

  Further, by disposing at least four negative lenses in succession, on the tele side, the light beam diameter toward each image point is narrower among the at least four negative lenses in the most negative lens, Since the lens on the most reduction side can be made thicker, the most negative lens on the most enlargement side and the negative lens on the most reduction side are aspherical lenses, so that among the at least four negative lenses, The most magnified aspheric lens performs aberration correction according to the angle of view so as to deal with off-axis aberrations such as distortion, and the most aspherical lens accommodates axial aberrations such as spherical aberration. Thus, it becomes possible to perform aberration correction common to the angle of view, and it is possible to correct various aberrations in a balanced and efficient manner.

  In addition, according to the projection display device of the present invention, by mounting the projection wide-angle zoom lens according to the present invention, the half angle of view at the wide-angle end becomes a wide angle of 45 degrees or more while having a zoom function, and Since it is possible to reduce the size of the device, it is possible to significantly improve the portability and usability of the device.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a wide-angle zoom lens for projection according to the present invention, and is a lens configuration diagram of Example 1 to be described later. This lens will be described below as a representative of this embodiment. In the figure, X represents the optical axis.

Wide-angle zoom lens for projection according to the present embodiment, in order from the magnification side, a focusing lens group G ₁ having a negative refractive power fixed during zooming, moves each during zooming are independently of each other A plurality of (three) zoom lens groups G _{2 to} G ₄ for zooming, and a lens position fixing lens group G ₅ having a positive refractive power that is fixed at the time of zooming (the position of the exit pupil of the entire system during zooming is The reduction side is telecentric. An aperture stop 3 (including a virtual one) is arranged so as to be independently movable during zooming.

  In the wide-angle zoom lens for projection according to the present embodiment shown in FIG. 1, a light beam incident from the right side of the paper and provided with image information on the image display surface 1 of the light valve passes through the glass block 2 and this wide-angle zoom for projection. The light is incident on the lens and is enlarged and projected in the left direction of the paper by the wide-angle zoom lens for projection. In FIG. 1, only the image display surface 1 of one light valve is shown for ease of viewing. However, in a projection display device, a light beam from a light source is separated into three primary color lights by a color separation optical system. In some cases, three light valves are provided for each primary color light so that a full color image can be displayed (see FIG. 5). By arranging color synthesizing means such as a cross dichroic prism at the position of the glass block 2, the three primary color lights can be synthesized.

The focusing lens group G ₁ is constituted by the enlargement four arranged in succession from the side of the negative lens (the first lens L _{1 ~} fourth lens L _4), the entire optical axis direction X by changing by moving, or the first lens L ₁ and the distance between the second lens L ₂ (floating), and performs focus adjustment. Further, in the group of focusing lenses G _1, most side of enlarged side of the first sheet of the negative lens is a negative lens (first lens L _1), and a negative lens on the most reduction side 4th negative lens The reduction side surface of the (fourth lens L ₄ ) is an aspherical surface.

Thus, in the focusing lens group G _1, by the most from the enlargement side are continuously arranged four negative lenses (first lens L _{1 ~} fourth lens L ₄₎ has a half view angle while more than 45 degrees and wide angle, it is possible to suppress the increase in diameter of the focusing lens group G _1, it is also possible to achieve a compact as a whole.

In the focusing lens group G ₁ , the first negative lens (first lens L ₁ ) and the fourth negative lens (fourth lens L ₄ ) from the enlargement side are aspherical lenses. by, i.e., in the focusing lens group G ₁ is greater angle changes and the optical path change due to zooming, by sandwiching the two negative lens (second lens L _2, a third lens L _3), spaced apart in the longitudinal Since an aspherical surface is disposed, it is possible to satisfactorily correct aberrations from the wide-angle end to the telephoto end.

The aspherical surface of the first negative lens is suitable for correcting aberration according to the angle of view so as to correspond to off-axis aberrations such as distortion and curvature of field, and the aspherical surface of the fourth negative lens. Is suitable for correcting aberrations common to the angle of view so as to correspond to axial aberrations such as spherical aberration. This is the focusing lens group G _1, by which arranged the negative lens of the four sequentially from the most magnification side, the telephoto side, the beam diameter toward the respective image point, a negative first sheet from the enlargement side This is because the lens can be made thin and the fourth lens can be made thick.

In the group of focusing lenses G _1, it is possible to arrange in succession 5 or more negative lenses from the most magnification side. However, Example 2 focusing lens group G ₁ Oite (see FIG. 2) described later, the fifth lens L ₅ which is arranged from the most magnification side to the 5th, is joined to the sixth lens L ₆ and color The first lens L ₁ to the fourth lens L ₄ that bear the function of erasing and conceptually differ from the first lens L ₁ to the fourth lens L ₄ . That is, a negative lens which is one element of the cemented lens as in the fifth lens L ₅ of the second embodiment, at least four negative arranged continuously from that has been "the most magnification side according to a first aspect of the present invention It is not included in "Lens".

  In the case of a wide-angle lens for projection with a fixed focal point (fixed magnification), it is preferable to arrange the first aspherical surface on the enlargement side and the second aspherical surface in the vicinity of the aperture stop or on the reduction side. Although it is possible to obtain aberration correction performance, in the case of a zoom lens, most of the change in the angle of view and the change in the optical path occur in the lens unit on the enlargement side, so the aberration correction effect of the second aspheric surface is reduced. End up. In addition, when an aspherical surface is disposed in the vicinity of the aperture stop or on the reduction side, there is a problem that the demand for the shape accuracy is extremely high and the manufacture becomes difficult. According to the wide-angle zoom lens for projection according to the present embodiment, it is possible to solve such a problem.

Further, the wide-angle zoom lens for projection according to the present embodiment is configured to satisfy the conditional expressions (1) and (2) (repeated below) described in the section for solving the problems.
2.5 <Bf / Fw (1)
1.5 <| Ff | / Fw <2.0 (2)
Here, Fw and Bf denotes the focal length and back focal length of the entire system at the wide angle end, Ff denotes a focal length of the focusing lens group G _1.

  Conditional expression (1) defines the ratio of the back focus Bf to the focal length Fw of the entire system at the wide angle end, and by satisfying this, the image display surface 1 of the projection wide angle zoom lens and the light valve It is possible to secure a sufficient installation space between them, and a color separation prism, a TIR prism, and the like can be installed in this space. On the other hand, if the lower limit value of conditional expression (1) is not reached, the back focus Bf becomes short, and it becomes difficult to secure an installation space for a color separation prism, a TIR prism, etc. between the image display surface 1 and the like.

Condition (2) is obtained by defining the ratio of the absolute value of the focal length Ff of the focusing lens group G ₁ to the focal length Fw of the whole system at the wide angle end, below this lower limit, sufficient angle It becomes difficult to ensure. Further, when the value exceeds the upper limit, compact becomes difficult if the entire system focusing lens group G ₁ is increased in size.

  Next, an example of a projection display device equipped with the projection zoom lens described above will be described with reference to FIG. The projection display device shown in FIG. 5 includes transmissive liquid crystal panels 11 a to 11 c as light valves, and uses the projection wide-angle zoom lens according to the above-described embodiment as the projection wide-angle zoom lens 10. Although not shown between the light source 20 and the dichroic mirror 12, white light from the light source 20 corresponds to each of three color light beams (G light, B light, and R light) via the illumination optical unit. Are incident on the transmissive liquid crystal panels 11a to 11c to be modulated, color-combined by the cross dichroic prism 14, and projected onto a screen (not shown) by the projection zoom lens 10. This apparatus includes dichroic mirrors 12 and 13 for color separation, a cross dichroic prism 14 for color composition, condenser lenses 16a to 16c, and total reflection mirrors 18a to 18c. The projection display apparatus according to the present embodiment uses the wide-angle zoom lens for projection according to the present embodiment, so that the half field angle at the wide-angle end is widened to 45 degrees or more while having a zoom function, and Since downsizing can be achieved, the portability and usability of the apparatus can be significantly improved.

  The projection wide-angle zoom lens according to the present invention is not limited to a use mode as a projection wide-angle zoom lens of a projection display device using a transmissive liquid crystal display panel. It can also be used as a wide-angle zoom lens for projection of an apparatus using other light modulation means.

  Specific examples of the wide-angle zoom lens for projection according to the present invention will be described below. In FIG. 2 showing the configuration of the second embodiment, members having the same effects as those of the first embodiment are denoted by the same reference numerals as those used in FIG.

<Example 1>
As shown in FIG. 1, the wide-angle zoom lens for projection according to Example 1 includes a focusing lens group G ₁ that has a fixed negative refractive power at the time of zooming, in order from the magnification side in the arrangement at the wide-angle end. Moving lens groups G ₂ and G ₃ during zooming, an aperture stop 3 movable independently during zooming, and a moving lens group G ₄ during zooming, and a pupil position that has a fixed positive refractive power during zooming it is arranged and fixed lens group G ₅ is, reduction side is telecentric. Further, the reduction side of the pupil position fixed lens group G _5, the image display surface 1 and a glass block 2 of the light valve are arranged from the reduction side in this order. The three zooming moving lens groups G _{2 to} G ₄ are configured to move independently from each other during zooming.

The focusing lens group G _1, as described above, is constituted by the enlargement four arranged in succession from the side of the negative lens (the first lens L _{1 ~} fourth lens L _4). The first lens L ₁ is made of bi-aspherical plastic lens having a negative refractive power in a paraxial region, the second lens L ₂ is made of a negative meniscus lens having a convex surface facing the magnification side, the first third lens L ₃ is composed of a biconcave negative lens having a surface with a stronger curvature directed onto the reduction side than the magnification side. Also, the fourth lens L ₄ is made from the reduction side of the lens base L _4G which is formed in the glass material, formed by joining the non-spherical portion L _4P thin formed of a plastic material composite aspherical lens . Incidentally, the fourth lens L _4, it is also possible to constitute a glass lens or a mold lens.

The zooming when moving lens group G ₂ is composed of a seventh lens L ₇ and the eighth lens L ₈ are both biconvex lens.
The zooming when moving lens group G ₃ includes a eighth lens L ₈ is a biconcave lens, has a ninth lens L ₉ Metropolitan a biconvex lens.

The zooming when moving lens group G ₄ includes a ninth lens L ₉ is a negative meniscus lens having a convex surface facing the magnification side, a tenth lens L ₁₀ is a biconvex lens, an eleventh lens L ₁₁ is a biconvex lens , a twelfth lens _{L 12} is a biconcave lens, has a thirteenth lens _{L 13} Metropolitan a biconvex lens. Incidentally, eleventh lens _{L 11} and the twelfth lens _{L 12} are cemented together.

The pupil position fixation lens group G ₅ is for the position of the exit pupil of the whole system during zooming arranged so as not to be changed, a fourteenth lens L ₁₄ is a negative meniscus lens having a convex surface on the magnification side It has become fifteenth lens _{L 15} Metropolitan a biconvex lens. Incidentally, fourteenth lens _{L 14} and the fifteenth lens _{L 15} are cemented together.

The shape of each aspheric surface in the first lens L ₁ and the fourth lens L ₄ is defined by the following aspheric expression. In the first lens L ₁ in which both surfaces are aspherical, an aberration correction effect can be obtained even if either one of the surfaces is aspherical, but a lens in which both surfaces are aspherical. It is more preferable that

The curvature radius R of each lens surface of the wide-angle zoom lens for projection according to Example 1 (normalized by setting the focal length of the entire system at the wide-angle end to 1: the same in the following examples), the center thickness of each lens, and each Air spacing between lenses (hereinafter referred to as “shaft upper surface spacing”) D (normalized by setting the focal length of the entire system at the wide-angle end as 1; the same in the following embodiments), the refractive index N of each lens at the d-line the value of the Abbe number [nu _d in d line _d of each lens, shown in the upper part of Table 1. In Table 1 and the following table, the surface number numbers indicate the order from the enlargement side, and the surface marked with * on the right side of the surface number is an aspheric surface. In Example 1 and Example 2 below, the radius of curvature R of these aspheric surfaces is shown as the value of the radius of curvature on the optical axis X in each table, but it is easy to see the drawing in the corresponding lens configuration diagram. Therefore, some lead lines are not necessarily drawn from the intersection with the optical axis X.

Further, the middle part of Table 1 shows values of constants K, A ₄ , A ₆ , A ₈ , A ₁₀ , A ₁₂ corresponding to each aspheric surface.
As described above, in the wide-angle zoom lens for projection according to the first embodiment, the zooming moving lens groups G _{2 to} G ₄ and the aperture stop 3 move in the optical axis X direction independently of each other during zooming. The lower part of Table 1 shows variable intervals (D ₉ , D ₁₃ , D ₁₇ , D ₁₈ , D ₂₇ ) at the wide-angle end (WIDE) and the telephoto end (TELE) and their intermediate position (MEDIAUM). Values are shown.

In Example 1, as shown in Table 1, the focal length Fw of the entire system at the wide angle end is 1.0 (the focal length Ft of the entire system at the telephoto end is 1.25), and the back focus Bf is 2.59. There, the focal length Ff of the focusing lens group _{G 1} has a -1.57. Therefore, the value corresponding to conditional expression (1) is 1.57, which satisfies conditional expression (1). The value corresponding to conditional expression (2) is 2.59, which satisfies conditional expression (2).

<Example 2>
As shown in FIG. 2, the wide-angle zoom lens for projection according to Example 2 includes a focusing lens group G ₁ having a negative refractive power that is fixed at the time of zooming in order from the magnification side in the arrangement at the wide-angle end. Moving lens groups G ₂ and G ₃ during zooming, an aperture stop 3 that can be moved independently during zooming, and moving lens groups G ₄ and G ₅ during zooming, and a fixed positive refractive power during zooming it is arranged and a pupil position fixation lens group G ₆ having a reduction side is telecentric. Further, the reduction side of the pupil position fixed lens group G _6, the image display surface 1 and a glass block 2 of the light valve are arranged from the reduction side in this order. The four zooming moving lens groups G _{2 to} G ₅ are configured to move independently from each other during zooming.

The focusing lens group G ₁ includes four negative lenses (first lens L ₁ to fourth lens L ₄ ) arranged continuously from the enlargement side and one negative lens (fifth lens L _5). ) And a cemented lens including one positive lens (sixth lens L ₆ ). The first lens L ₁ is a double-sided aspheric plastic lens having negative refractive power in the paraxial region, and the second lens L ₂ and the third lens L ₃ are negative with the convex surface facing the enlargement side. It consists of a meniscus lens. Also, the fourth lens L ₄ is made from the magnification side of the lens base L _4G which is formed in the glass material, formed by joining the non-spherical portion L _4P thin formed of a plastic material composite aspherical lens . Incidentally, the fourth lens L _4, it is also possible to constitute a glass lens or a mold lens. The fifth lens L ₅ is made of a biconcave lens, the sixth lens L ₆ is composed of a biconvex lens.

The zooming when moving lens group G ₂ is composed of a seventh lens L ₇ is a negative meniscus lens having a convex surface facing the magnification side.
The zooming when moving lens group G ₃ includes a eighth lens L ₈ is a biconvex lens, has a ninth lens L ₉ Metropolitan is a negative meniscus lens having a convex surface directed toward the reduction side. Incidentally, the eighth lens _{L 8} and the ninth lens _{L 9} are joined together.
The zooming when moving lens group G ₄ includes a tenth lens L ₁₀ is a negative meniscus lens having a convex surface facing the magnification side, consists eleventh lens L ₁₁ Metropolitan a biconvex lens. Incidentally, a tenth lens _{L 10} and the eleventh lens _{L 11} are cemented together.

The zooming when moving lens group G ₅ includes a twelfth lens L ₁₂ is a biconcave lens, a thirteenth lens L ₁₃ is a biconvex lens, a fourteenth lens L ₁₄ and a negative meniscus lens having a convex surface on the magnification side a fifteenth lens _{L 15,} formed of a sixteenth lens _{L 16} Metropolitan a biconvex lens. Incidentally, twelfth lens _{L 12} and the thirteenth lens _{L 13,} and 14 lens _{L 14} and the fifteenth lens _{L 15} are respectively joined together.
The pupil position fixation lens group G ₆ is for the position of the exit pupil of the entire system was arranged so as not to be changed during zooming, consists seventeenth lens L ₁₇ is a biconvex lens.

The shape of each aspheric surface in the first lens L ₁ and the fourth lens L ₄ is defined by the above-mentioned aspheric expression. In the first lens L ₁ in which both surfaces are aspherical, an aberration correction effect can be obtained even if either one of the surfaces is aspherical, but a lens in which both surfaces are aspherical. It is more preferable that

The curvature radius R of each lens surface of the wide-angle zoom lens for projection according to Example 2, the center thickness of each lens and the axial top surface distance D between each lens, the refractive index N _d of each lens at the d line, and the d line of each lens. the value of the Abbe number [nu _d in, shown in the upper part of Table 2.

The middle part of Table 2 shows values of constants K, A ₄ , A ₆ , A ₈ , A ₁₀ , A ₁₂ corresponding to each aspheric surface.
Further, as described above, in the wide-angle zoom lens for projection according to Example 2, the zooming moving lens groups G _{2 to} G ₅ and the aperture stop 3 move in the optical axis X direction independently of each other during zooming. The lower part of Table 2 shows variable intervals (D ₁₂ , D ₁₄ , D ₁₇ , D ₁₈ , D ₂₁ , D) at the wide-angle end (WIDE) and the telephoto end (TELE) and their intermediate position (MEDIAUM). The value of D ₂₉ ) is shown.

In Example 2, as shown in Table 2, the focal length Fw of the entire system at the wide-angle end is 1.0 (the focal length Ft of the entire system at the telephoto end is 1.33), and the back focus Bf is 2.75. There, the focal length Ff of the focusing lens group _{G 1} has a -1.90. Therefore, the value corresponding to conditional expression (1) is 1.90, which satisfies conditional expression (1). The value corresponding to conditional expression (2) is 2.75, which satisfies conditional expression (2).

  3 and 4 show various aberrations (spherical aberration, distortion, astigmatism, and lateral chromatic aberration) at the wide-angle end (WIDE) and the telephoto end (TELE) of the wide-angle zoom lens for projection according to Examples 1 and 2. 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. 3 and 4, the projection wide-angle zoom lenses according to Examples 1 and 2 are well corrected for each aberration including distortion and lateral chromatic aberration, and have a half field angle of 51.1 to 52.7 at the wide-angle end. The projection lens has an F number of 1.8 and a wide-angle and bright projection lens.

  The wide-angle zoom lens for projection according to the present invention is not limited to the above-described embodiment, and various modifications can be made. For example, the curvature radius R and the axial top surface distance D of each lens are appropriately changed. It 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 wide-angle zoom lens for projection of the present invention are possible. As the light valve, for example, a transmissive or reflective liquid crystal display element, or a micro mirror element in which a large number of micro mirrors capable of changing the inclination are formed on a substantially flat surface (for example, manufactured by Texas Instruments). Digital micromirror device) can be used. Also, as the illumination optical system, an appropriate configuration corresponding to the type of light valve can be adopted.

Configuration of a wide-angle zoom lens for projection according to Embodiment 1 Configuration of a wide-angle zoom lens for projection according to Example 2 Various aberration diagrams of the wide-angle zoom lens for projection according to Example 1 Various aberration diagrams of the wide-angle zoom lens for projection according to Example 2 1 is a schematic configuration diagram of a projection display device according to an embodiment.

Explanation of symbols

1 image display surface 2 glass block 3 aperture 10 wide-angle zoom lens for projection 11a~11c transmissive liquid crystal panel 12, 13 dichroic mirror 14 cross dichroic prism 16a~16c condenser lens 18a~18c total reflection mirror 20 light source G ₁ ~G ₆ lens group L ₁ ~L ₁₇ lens R ₁ to R of curvature such as ₃₃ lens surface radius D ₁ to D ₃₃ axial distance X optical axis

Claims (2)

In order from the enlargement side, a focusing lens group that has a fixed negative refractive power at the time of zooming, a plurality of zooming moving lens groups that move independently from each other at the time of zooming, and a zooming lens group A wide-angle zoom lens for projection in which a lens group for fixing the pupil position and a positive refractive power is disposed,
The focusing lens group includes a lens portion including only four negative lenses arranged continuously from the most magnified side,
Of the four negative lenses, only the most negative lens and the most negative lens are aspherical lenses,
When the focal length of the entire system at the wide angle end is Fw, the back focus is Bf, and the focal length of the focusing lens group is Ff, the following conditional expressions (1) and (2) are satisfied. Wide-angle zoom lens for projection.
2.5 <Bf / Fw (1)
1.5 <| Ff | / Fw <2.0 (2) Light source, light valve and an illumination optical unit for a light beam guided to the light valve from the light source, a claim 1 Symbol mounting wide-angle zoom lens for projection, and projection angle zoom reduction side is formed by a telecentric A projection display device comprising: a lens; wherein the light beam from the light source is light-modulated by the light valve and projected onto a screen by the wide-angle zoom lens for projection.

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