JPH04366803A - Projection lens and projection type display device using the same - Google Patents

Abstract

PURPOSE:To provide the wide-angle projection lens of simple lens constitution which has a short projection distance and secures the sufficient quantity of marginal light even when not only a normal projection tube, but also a projection tube having a directional brightness distribution are used. CONSTITUTION:The lens system consists of a 3rd lens group 3 consisting of a spherical lens which has >=70% of the power of the whole lens system and 1st, 2nd, 4th, and 5th lens groups 1, 2, 4, & 5 consisting of small-power aspherical lenses. The respective lens shapes of the 1st, 2nd, 4th, and 5th lens groups 1, 2, 4, and 5 are so determined that the luminous flux emitted from the object point of the most peripheral part of the screen of a cathode-ray tube panel 6 passes a place on the incidence surface of the 3rd lens group 3 at a distance from the optical axis.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable not only to ordinary projection tubes in which the luminance distribution on the fluorescent surface is Lambertian distribution, but also in particular to the use of interference filters formed on the inner wall surface of the projection tube glass panel. A wide-angle projection lens with a short projection distance that efficiently captures the light emitted from the fluorescent surface and provides a bright projected image to the periphery even when combined with a projection tube that has directivity. The present invention relates to a projection display device using.

0002

2. Description of the Related Art With the diversification of video sources, large-screen display devices are becoming widespread. In such large-screen display devices, the projection type is more advantageous than the direct view type in terms of weight, depth, and cost, but it is disadvantageous in terms of screen brightness. In order to compensate for the darkness of the screen, which was a drawback of these projection display devices, and to ensure brightness comparable to that of a direct view type, attempts have been made to reduce the F value of the projection lens, and currently it is down to around F1.0. As apertures have become larger, designs are reaching their limits even with the use of aspherical lenses.

[0003] Also, in projection tubes, there is a limit to the increase in the amount of light that can be emitted due to the lifespan of the high current density cathode and phosphor, the strength limit of the glass bulb, etc. For this reason, it was thought that the improvement in the brightness (luminance) of the screen of a projection display device was reaching its limit using the conventional method.

[0004] Under such circumstances, Japanese Patent Application Laid-open No. 10034/1983
As described in Japanese Patent Application No. 7, a projection tube has been proposed in which the fluorescent surface of the projection tube is optically modified to give directionality to the luminance distribution from the fluorescent surface. This projection tube has a basic configuration with an interference filter between the phosphor and the panel glass, so the amount of transmitted light that enters from the phosphor at a small angle of incidence with respect to the normal to the inner surface of the panel glass is large. When the incident angle becomes large, the amount of transmitted light decreases rapidly. As a result, the panel glass has a directional brightness distribution in which the brightness in the normal direction is higher than usual, and the brightness decreases rapidly as it deviates from the normal direction.

On the other hand, when the light beam emitted from the projection tube is taken in by the projection lens, the light beam emitted from the periphery of the screen of the projection tube is inevitably only at a large angle with respect to the normal direction of the panel glass. I can't take it in. Therefore, when using a projection tube with the above-mentioned directional luminance distribution as a projection tube, only the luminous flux whose luminance has weakened due to the directivity of the projection tube can be captured from the luminous flux emitted from the periphery of the screen of the projection tube. First, the amount of peripheral light decreases significantly, so the characteristics that the projection lens should have include not only increasing the aperture, but also ensuring a sufficient amount of light emitted from the peripheral area of the projection tube screen. .

Incidentally, in recent years, in order to make projection display devices more compact, a projection lens with a short projection distance has been developed. 25091
There is a configuration disclosed in Publication No. 6.

In this projection lens, in order to shorten the projection distance and realize a wide-angle (large angle of view) lens with a large aperture of f/1.0, a single double-convex glass lens with a large condensing power is used. , sandwiching the biconvex glass lens between them, two aspherical plastic lenses with small power are placed on the projection tube side and one on the screen side, and the biconvex glass lens is placed as close to the fluorescent surface of the projection tube as possible. arranged to form a lens system. Furthermore, the shape of the two aspherical plastic lenses arranged between the two aspherical plastic lenses is controlled so that the light beam incident from the peripheral part of the screen of the projection tube passes through approximately the center of the biconvex glass lens. By adopting such a configuration, despite the large aperture and short projection distance, it is possible to satisfactorily correct aberrations of the light beam incident from the peripheral portion of the screen.

[0008]

[Problems to be Solved by the Invention] However, in the conventional projection lens described above, when capturing the luminous flux emitted from the peripheral part of the screen of the projection tube, it is difficult to compare the normal projection lens with respect to the normal direction of the panel glass. As a result, a light beam having an even larger angle is taken in. For this reason, when using a projection tube with a directional brightness distribution as described above, the luminous flux emitted from the periphery of the screen of the projection tube will receive a luminous flux whose luminance is further weakened. However, there was a problem in that the amount of peripheral light further decreased.

The present invention solves the problems of the prior art and ensures a sufficient amount of peripheral light even when using not only a normal projection tube but also a projection tube with directional brightness distribution. Furthermore, it is an object of the present invention to provide a wide-angle projection lens with a short projection distance and a simple lens configuration.

0010

[Means for Solving the Problems] In order to achieve the above object, in a lens system composed of a glass lens having a large positive power and a plastic aspherical lens having a small power, a lens that is taken into the lens system from the periphery of the screen is provided. The configuration is such that the light beam passes through the peripheral area of the glass power lens, which does not include the optical axis. Furthermore, aberrations such as astigmatism and distortion, which especially increase due to this, are effectively corrected by the aspherical lens arranged on the screen side.

[0011]

[Operation] The entire lens system is composed of five groups arranged in order from the screen side. The fifth lens group, which is closest to the projection tube, is a concave lens for field curvature correction, and has an aperture of
Set the curvature to a large value. The fourth lens group has weak positive power in the center and curves the peripheral part toward the screen.
The light rays incident from the periphery of the screen are moved in the optical axis direction, and the aperture of the powerful third lens group is made as small as possible. The third lens group has about 70% or more of the total power. All light rays from the peripheral area are set so as not to pass through the optical axis of the entrance surface of the third lens group. The second lens group has positive power and has a meniscus shape with an apex on the screen side to correct low-order spherical aberration. The first lens group has a convex meniscus shape with the apex at the center facing the projection tube, so that astigmatism occurring at the exit surface of the third lens group can be avoided.
Corrects distortion aberration and higher-order spherical aberration. By adopting such a configuration, it is possible to secure the amount of peripheral light corresponding to the directional projection tube and to project a high-resolution image at a short projection distance.

0012

[Embodiment] The first embodiment of the present invention will be described below with reference to FIGS.
This will be explained with reference to FIG. 3, FIG. 4, FIG. 5, Table 1, and Table 2. FIG. 1 is a sectional view showing the configuration of a projection lens as a first embodiment of the present invention. In Figure 1, starting from the screen side,
A first lens group 1 consisting of a first lens, a second lens group 2 consisting of a second lens, and a third lens group 3 consisting of a third lens
, a fourth lens group 4 consisting of a fourth lens, and a fifth lens 5'
and a fifth lens group 5 consisting of a transparent medium 5''.

Tables 1 and 2 show specific data for each element of these lens groups, of which Table 1 shows the spherical system and Table 2 shows the aspheric system. Note that the spherical system represents a lens region near the optical axis, and the aspherical system represents a lens region on its outer periphery.

First, the spherical system will be explained. In Table 1, since the screen is flat, the radius of curvature is ∞, and the distance on the optical axis from the screen to the surface S1 of the first lens (
The surface spacing) is 769 mm. Further, the radius of curvature of the surface S1 of the first lens is -56.697 mm, the distance between the surfaces S1 and S2 of the first lens is 10 mm, and the refractive index therebetween is 1.49345. still,
For terms with a blank refractive index, the medium between the surfaces is air (refractive index 1
．． 0).

Similarly, the last step is to remove the cathode ray tube panel 6.
The radius of curvature of the fluorescent surface P1 is -350 mm, the thickness on the optical axis (interface spacing) is 14.6 mm, and the refractive index is 1.56245. Note that the refractive index referred to here is at wavelength 545.
It is the refractive index for light rays of nm.

Next, the aspherical system will be explained. Surfaces S1 and S2 of the first lens, surfaces S3 and S4 of the second lens, and the fourth
Lens surfaces S7 and S8, and surfaces S9 and S1 of the fifth lens 5'
0 is an aspherical surface, and Table 2 shows data of their aspherical coefficients.

[0017] The aspherical coefficient here refers to the surface shape.

[Number 1
] These are the coefficients CC, AE, AF, AG, and AH when expressed as .

However, in Equation 1, Z is the amount of displacement of the lens surface in the Z-axis direction (r of function), where r is the radial distance and Rd is the paraxial radius of curvature. Therefore, once the CC, AE, AF, AG, and AH coefficients are determined, the height of the lens surface, that is, the surface shape, is determined by the above equation.

In the projection lens of this embodiment, the first lens forming the first lens group 1 has an aspherical convex meniscus shape with its apex directed toward the projection tube (cathode ray tube).
Conversely, the second lens forming the lens group 2 has an aspherical convex meniscus shape with its apex facing toward the screen, and the third lens forming the third lens group 3 has a
The fourth lens forming the fourth lens group 4 has an aspherical shape with a biconvex center and a meniscus at the periphery. The fifth lens 5' forming the projection tube has a large negative power when combined with the cooling liquid 5'' provided between the projection tube and the projection tube.

[0020] Then, the relative power of each group is f0/f1~ with reference to the power 1/f0 of the entire lens system.
f0/f5 are: First lens group 1; f0/f1=0.145 Second lens group 2; f0/f2=0.080 Third lens group 3; f0/f3=0.821 Fourth lens group 4; f0/f4=0.276 Fifth lens group 5; f0/f5=-0.525 is set.

In the projection lens of this embodiment, the third lens group 3 having the largest positive power is largely involved in image formation.
The other lens groups are aspheric lens groups for aberration correction. Of these aspherical lens groups, all except the fifth lens group 5 give positive power to the center. The reason for this is to disperse the positive power of the third lens group 3 to other groups to efficiently correct spherical aberration. In addition, at all angles of view, the light flux before passing through the third lens group 3 is thin, and the light flux after passing through it is thick, so the third lens group 3
The first and second lens groups 1 are located closer to the screen than the
2 uses an aspheric surface to delicately control and correct the aberration of the luminous flux at each angle of view, whereas the fourth and fifth lens groups 4 and 5 correct the aberration of the luminous flux to the first and second lens groups 1 and 2. The incident conditions of the lens are controlled to facilitate aberration correction by the first and second lens groups 1 and 2.

The functions of each lens group will be described below in order from the projection tube side, which is the incident side. The fifth lens group 5 is a lens group for correcting field curvature using a fifth lens 5' and a cooling liquid 5''.This lens group 5 is the lens group through which the light beam emitted from the peripheral part of the fluorescent surface of the projection tube first passes. Therefore, the lower limit of negative power and aperture are determined in order to take in as much of the lower limit rays as possible, taking into account the directivity of the projection tube brightness distribution.In addition, the projection tube fluorescent surface is curved. This makes it advantageous to correct the curvature of field and secure the amount of peripheral light.The fifth lens 5' is a concave lens whose exit surface toward the screen is aspherical, and the image point at each angle of view is Flare in the sagittal direction is corrected. Furthermore, the heat of the projection tube is radiated by the cooling liquid 5''.

The fourth lens group 4 consists of a fourth lens which is an aspherical lens. The fourth lens has a biconvex shape at the center to correct spherical aberration. However, in the periphery,
In order to secure the amount of peripheral light, it is necessary to introduce light rays as close as possible to the normal to the phosphor surface into the lens system. If the peripheral part is also made into a biconvex shape, the peripheral rays will be bent in the optical axis direction, making it easier for more rays to enter, but since the third lens group 3 has a large positive power, the peripheral part luminous flux will be It tends to become thinner, making it difficult to correct aberrations by the first and second lens groups 1 and 2. Therefore, the local shape required for the periphery of the fourth lens is:
It has a shape that bends the light rays at the periphery toward the optical axis and thickens the luminous flux at the periphery, and as shown in Figure 1, at least the periphery of the screen-side surface is greatly curved toward the screen. be.

The third lens group 3 is a spherical lens.
Consists of lenses. The third lens is the glass lens with the largest power as described above. In order to suppress low-order spherical aberration to some extent, the radius of curvature of the surface on the screen side is set smaller than that on the projection tube side.

The second lens group includes a second lens which is an aspherical lens.
Consists of lenses. The second lens has a convex meniscus shape with an apex on the screen side, and lower-order spherical aberration and coma aberration that cannot be corrected due to bending of the central part of the fourth lens group 4 and the glass lens of the third lens group 3. is being corrected.

The first lens group 1 is an aspherical lens.
It consists of a lens 1. The first lens has a central portion with an apex on the projection tube side. The reason why the central part of the first lens is curved toward the projection tube is due to astigmatism, which occurs because the light beam incident from the peripheral part is largely bent by the exit surface of the third lens group 3, which has a particularly large curvature. This is to correct the distortion by passing through a curved surface in contrast to this surface. Further, a diaphragm is inserted between the first lens group 1 and the second lens group 2 to block unnecessary light rays at an intermediate angle of view and guide useful light rays at a peripheral angle of view to the first lens. Therefore, at the periphery of the first lens, it is possible to independently correct the upper end of the luminous flux at each angle of view, and as a result, the periphery of the first lens has a shape that is curved in the opposite direction to the central part. becomes.

Next, the MTF by the projection lens of this embodiment
(Modulation Transfer Func
tion (modulation transfer function) performance is shown in FIG. In FIG. 3, the dashed line is meridional.
The solid line indicates the characteristic in the sagittal direction, and the solid line indicates the characteristic in the sagittal direction. Note that these characteristics are for a horizontal resolution of 300 TV lines. As is clear from Fig. 3, the above lens configuration allows aberrations to be well corrected at each angle of view.
The performance is sufficient for a C-type projection television.

FIG. 4 shows the results of calculating and evaluating changes in the light quantity ratio in the projection lens of this embodiment for the normal projection tube and the directional projection tube. In FIG. 4, the broken line shows the characteristics for a normal projection tube, and the solid line shows the characteristics for a directional projection tube. Note that the gain of the directional projection tube uses data 1.4 times that of the normal projection tube. As is clear from Fig. 4, at a relative angle of view of 1.0, in the case of a normal projection tube, 2
7.3%, and 28.2% in the case of the directional projection tube, which is a practically acceptable marginal illumination ratio regardless of which type of projection tube is used.

FIG. 5 shows changes in distortion in the projection lens of this embodiment. As is clear from Fig. 5, the relative angle of view 1
．． 0, it is 7.9%, which is a considerably larger value than that of a normal projection lens. This is because the fluorescent surface of the projection tube is curved and the angle of view is extremely large at 76° despite the fact that the entrance pupil is far away. However, due to recent high-precision convergence functions, this is not a problem. In this example, the power of the third lens group 3 is set to 0.8
Although it is set to 2, this power may be larger or smaller.

Embodiments of the present invention in which the power of the third lens group 3 is reduced will be described below as second and third embodiments. Tables 3 and 4 respectively show specific data for each element of the lens group in the second example of the invention.

In the second embodiment, the relative powers f0/f1 to f0/f5 of each group based on the power 1/f0 of the entire lens system are as follows: First lens group 1; f0/f1= 0.147 2nd lens group 2; f0/f2= 0.098 3rd lens group 3; f0/f3= 0.782 4th lens group 4; f0/f4= 0.307 5th lens group 5; f0/ It is set as f5=-0.538.

Tables 5 and 6 each show specific data for each element of the lens group in the third embodiment of the present invention. In the third embodiment, the relative powers f0/f1 to f0/f5 of each group based on the power 1/f0 of the entire lens system are as follows: first lens group 1; f0/f1=0.088 2nd lens group 2; f0/f2 = 0.085 3rd lens group 3; f0/f3 = 0.778 4th lens group 4; f0/f4 = 0.371 5th lens group 5; f0/f5 = - It is set to 0.558.

In both embodiments, the power of the third lens group 3 is reduced and the power of the fourth lens group 4 is increased, but in the second embodiment, the power of the first lens group 1 is reduced. is kept almost equivalent to the first example, while the third example
In the embodiment, the power of the first lens group 1 is further transferred to the fourth lens group 4, and the two are different in this point.

On the other hand, an embodiment of the present invention in which the power of the third lens group 3 is increased will be described below as a fourth embodiment. Tables 7 and 8 each show specific data for each element of the lens group in the fourth example of the present invention.

In the fourth embodiment, the relative powers f0/f1 to f0/f5 of each group based on the power 1/f0 of the entire lens system are as follows: First lens group 1; f0/f1= 0.167 2nd lens group 2; f0/f2= 0.036 3rd lens group 3; f0/f3= 0.867 4th lens group 4; f0/f4= 0.252 5th lens group 5; f0/ It is set as f5=-0.498. By increasing the power of the third lens group 3,
The power of the second lens group 2 is reduced.

In the above embodiments, the lens length from the fluorescent surface of the projection tube to the exit surface of the first lens group 1 is relatively long, about 190 mm or more, but an embodiment of the present invention in which the total length is further shortened is shown. will be described below as a fifth example. Table 9
Table 10 and Table 10 respectively show specific data for each element of the lens group in the fifth example of the present invention.

In the fifth embodiment, the relative powers f0/f1 to f0/f5 of each group based on the power 1/f0 of the entire lens system are as follows: First lens group 1; f0/f1= 0.151 2nd lens group 2; f0/f2= 0.084 3rd lens group 3; f0/f3= 0.827 4th lens group 4; f0/f4= 0.276 5th lens group 5; f0/ It is set as f5=-0.533. This power distribution is similar to the first embodiment, but the total lens length is shortened by about 10 mm.

Furthermore, the first lens group 1, the second lens group 2,
The powers of the fourth lens group 4 can be transferred to each other to a certain extent. Therefore, such embodiments of the present invention will be described in the sixth, seventh, and third embodiments.
An eighth example will be described below. Table 11 and Table 12
1 and 2 respectively show specific data of each element of the lens group in the sixth embodiment of the present invention.

In the sixth embodiment, the relative powers f0/f1 to f0/f5 of each group based on the power 1/f0 of the entire lens system are as follows: First lens group 1; f0/f1= 0.107 2nd lens group 2; f0/f2= 0.104 3rd lens group 3; f0/f3= 0.828 4th lens group 4; f0/f4= 0.258 5th lens group 5; f0/ It is set as f5=-0.375.

Further, Tables 13 and 14 respectively show specific data for each element of the lens group in the seventh embodiment of the present invention. In the seventh embodiment, the relative powers f0/f1 to f0/f5 of each group based on the power 1/f0 of the entire lens system are as follows: first lens group 1; f0/f1=0.161 2nd lens group 2; f0/f2 = 0.069 3rd lens group 3; f0/f3 = 0.823 4th lens group 4; f0/f4 = 0.260 5th lens group 5; f0/f5 = - It is set to 0.531.

Tables 15 and 16 each show specific data for each element of the lens group in the eighth embodiment of the present invention. In the eighth embodiment, the relative powers f0/f1 to f0/f5 of each group based on the power 1/f0 of the entire lens system are as follows: first lens group 1; f0/f1=0.148 2nd lens group 2; f0/f2 = 0.105 3rd lens group 3; f0/f3 = 0.815 4th lens group 4; f0/f4 = 0.183 5th lens group 5; f0/f5 = - It is set to 0.426.

In these three embodiments, the power distribution of the seventh embodiment is close to that of the first embodiment, whereas in the sixth embodiment, the power of the first lens group 1 is distributed to the second lens. This is an example in which the power of the fourth lens group 4 is transferred to the second lens group 2, and the eighth example is an example in which the power of the fourth lens group 4 is transferred to the second lens group 2.

The above are examples of the present invention. In these examples, the angle that the lower limit ray from the periphery of the phosphor surface makes with the normal to the phosphor surface is 10°, and the angle of the upper limit ray is 10°. 23°
As the entire luminous flux passes through the part of the incident surface of the third lens group 3, which has the strongest power, that does not include the optical axis, it is possible to obtain sufficient peripheral light even when using not only a directional projection tube but also a normal projection tube. You can get the amount of light.

Furthermore, in the interference film projection tube, the red spurious component emitted by the green phosphor can be cut by setting, so the lens does not need to perform chromatic aberration correction and can obtain sufficiently good MTF performance. .

[0045]

[Table 1]

[0046]

[Table 2]

[0047]

[Table 3]

[0048]

[Table 4]

[0049]

[Table 5]

[0050]

[Table 6]

[0051]

[Table 7]

[0052]

[Table 8]

[0053]

[Table 9]

[0054]

[Table 10]

[0055]

[Table 11]

[0056]

[Table 12]

[0057]

[Table 13]

[0058]

[Table 14]

[0059]

[Table 15]

[0060]

[Table 16]

[0061]

According to the present invention, a sufficient amount of peripheral light can be secured not only when a normal projection tube is used but also when a projection tube with a directional brightness distribution is used as the projection tube. Moreover, a wide-angle projection lens with a short projection distance can be realized with a simple lens configuration.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the configuration of a projection lens as a first embodiment of the present invention.

FIG. 2 is an explanatory diagram for explaining Z in Equation 1.

[Fig. 3] MTF for relative angle of view in the first embodiment
FIG.

FIG. 4 is a characteristic diagram showing the characteristics of the light quantity ratio with respect to the relative angle of view in the first embodiment.

FIG. 5 is a characteristic diagram showing the distortion characteristics with respect to the relative angle of view in the first embodiment.

[Explanation of symbols]

1... First lens group, 2... Second lens group, 3... Third lens group, 4... Fourth lens group, 5... Fifth lens group, 6... Cathode ray tube panel.

Claims (15)

[Claims] Claim 1: A projection lens that is placed in front of an image display device and that enlarges and projects the image displayed on the image display device onto a screen, which has a power ratio of 70% or more relative to the power of the entire lens system. The first lens group (
3), a plurality of aspheric lens groups (1, 2, 4, 5),
The light flux emitted from the object point at the most peripheral part of the screen of the image display device (6) is transmitted to the first lens group (
3) A projection lens characterized in that the shape of each lens of the aspherical lens group is configured such that the incident surface of the first lens group (3) passes through a portion other than the optical axis of the first lens group (3). 2. The projection lens according to claim 1, wherein the first lens group (3) has a radius of curvature of a lens surface on the screen side that is smaller than a radius of curvature of a lens surface on the image display device side. Characteristic projection lens. 3. In the projection lens according to claim 1 or 2, when the power of the entire lens system is 1/f0 and the power of the first lens group (3) is 1/f, the power of the first lens group (3) is 1/f. A projection lens characterized in that the ratio f0/f of the power of the lens group (3) to the power of the entire lens system is within the range of 0.77≦f0/f≦0.87. 4. In the projection lens according to claim 1, the second lens group (1) disposed closest to the screen among the plurality of aspheric lens groups has at least a central portion thereof. 1. A projection lens characterized in that the projection lens has a meniscus shape with an apex on the side of an image display device. 5. The projection lens according to claim 1, 2, 3, or 4, of the plurality of aspheric lens groups,
The second lens group (1) disposed closest to the screen is a projection lens characterized in that its peripheral portion is curved in the opposite direction to its central portion. 6. In the projection lens according to claim 4, when the power of the entire lens system is 1/f0, and the power of the central portion of the second lens group (1) is 1/f', The ratio f0/f' of the power at the center of the second lens group (1) to the power of the entire lens system is 0.
A projection lens characterized in that it is within the range of 1≦f0/f'≦0.17. 7. The projection lens according to claim 4, 5 or 6, wherein among the plurality of aspherical lens groups, the first lens group (3) and the second lens group (1) A projection lens characterized in that the third lens group (2) disposed therebetween has positive power. 8. The projection lens according to claim 1, 2, 3, 4, 5, 6, or 7, wherein the fourth lens group is located closest to the image display device among the plurality of aspheric lens groups. (5) A projection lens characterized by having negative power. 9. The projection lens according to claim 8, wherein the projection lens is arranged between the first lens group (3) and the fourth lens group (5) among the plurality of aspheric lens groups. The fifth lens group (4) is a projection lens characterized in that at least its central portion has a biconvex shape. 10. The projection lens according to claim 1, wherein the plurality of aspherical lens groups include a second lens group (1 ), a third lens group (2) having a relatively weak positive power, a fourth lens group (5) having a negative power, and a fifth lens having a biconvex shape at least in its center. group (4), and these plural aspheric lens groups and the first lens group (3).
is the second one from the screen side to the image display device side.
lens group (1), third lens group (2), first lens group (3), fifth lens group (4), fourth lens group (
5) A projection lens characterized in that the lenses are arranged in the following order. 11. The projection lens according to claim 10, wherein the power of the entire lens system is 1/f0, the power of the center portion of the first lens group (3) is 1/fA, and the power of the second lens group (3) is 1/fA. The power at the center in (1) is 1/fB
, the power at the center of the third lens group (2) is 1/fC, the power at the center of the fourth lens group (5) is 1/fD, and the power at the center of the fifth lens group (4) is 1/fC. When the power at the center is 1/fE, the ratio f0/fA of the power at the center of the first lens group (3) to the power of the entire lens system is 0.77≦f0/fA≦0.87. The power at the center of the second lens group (1) is
The ratio f0/fB to the power of the entire lens system is 0.1
≦f0/fB≦ 0.17 Third lens group (2)
The ratio f0/fC of the power at the center to the power of the entire lens system is 0.03≦f0/fC≦0.11 The power at the center in the fourth lens group (5),
The ratio f0/fD to the power of the entire lens system is -0.56
≦f0/fD≦-0.37 The power at the center of the fifth lens group (4) is
The ratio f0/fE to the power of the entire lens system is 0.18≦
A projection lens characterized in that f0/fE≦0.38. 12. The projection lens according to claim 7, 10 or 11, wherein the third lens group (2) has a meniscus shape with an apex on the screen side. 13. The projection lens according to claim 9, 10 or 11, wherein the fifth lens group (4) has a meniscus shape with a peripheral portion thereof curved toward the screen. . [Claim 14] Claims 1, 2, 3, 4, 5, 6, 7
, 8, 9, 10, 11, 12 or 13, wherein the image display device is a projection tube having a fluorescent surface curved in the shape of an arc with its center on the screen side. projection lens. 15. An image display device comprising: an image display device that displays an image; and a projection lens disposed in front of the image display device that enlarges and projects the image displayed on the image display device onto a screen. In the projection display device according to any one of claims 1, 2, 3, 4, 5, 6, 7, 8, wherein a projection tube having a directional light emission luminance distribution is used as the image display device, and the projection lens is used as the projection tube. 9, 10, 11
, 12 or 13. A projection display device characterized by using the projection lens described in .