JPH11211979A - Projection image correcting lens, projection lens device, and projection type display device - Google Patents

Abstract

(57) Abstract: Provided is an aspect ratio correction device for reducing a pixel shift of a projected image when stack projection is performed using a plurality of projection display devices. SOLUTION: The projection image correction lens includes a first lens 23 of a plano-concave cylindrical lens and a second lens 24 of a plano-convex cylindrical lens in order from the screen side. By changing the air gap between the two cylindrical lenses 23 and 24 and the inclination angle of at least one of the cylindrical lenses, the aspect ratio and trapezoidal distortion of the projected image can be changed. If a plurality of projection display devices are arranged in parallel and a projection image correction lens is arranged on the emission side of each projection lens, it is possible to reduce the pixel shift between the two projection images.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type display apparatus which obtains a bright projection image by superposing respective projection images on a screen by using a plurality of projection type display apparatuses. The present invention relates to a projection image correction lens and a projection lens device for reducing a pixel shift of a plurality of projection images.

[0002]

2. Description of the Related Art In order to obtain a large-screen image, a method of forming an optical image corresponding to an image signal on a light valve, irradiating the optical image with light, and enlarging and projecting the image on a screen by a projection lens is well known. Have been. Recently, a projection display device using a liquid crystal panel as a light valve has been commercialized (for example, Japanese Patent Application Laid-Open No. 62-133424). The LCD panel is used to obtain high quality projected images.
It is becoming mainstream to use twisted nematic (TN) liquid crystal as a liquid crystal material, use an active matrix type in which a TFT is provided for each pixel as a switching element, and use three liquid crystal panels for red, green, and blue. .
Recently, the light output of the projection display device has been greatly improved as compared with the past, due to the improvement of the aperture ratio of the liquid crystal panel, the development of a small lamp with high brightness, and the like.

[0003] In order to further brighten a projected image, a method of stacking each projected image on a screen using a plurality of projection display devices (stack projection) has been conventionally known.

[0004] Fig. 16 shows an example of stack projection using two projection display devices. The two projection display devices 1 and 2 are arranged vertically, and the lower projection display device 1 uses liquid crystal so that the optical axis 4 of the projection lens 3 passes through the lower end 7 of the projection image 6 on the screen. The optical axis 4 of the projection lens 3 is shifted upward with respect to the screen center 9 of the panel 8. The upper projection display device 2 also shifts the optical axis 13 of the projection lens 12 upward with respect to the screen center 11 of the liquid crystal panel
The two projected images are overlapped. Projected image 6
In order not to be blocked by the projection display devices 1 and 2, the two projection display devices 1 and 2 are lower than the screen center 14 of the projection image 6. Since the projected images are superimposed using two projection display devices, the projected image is twice as bright as when only one projector is used.

[0005]

In the configuration shown in FIG. 16, when the distortion of the projection lens is large, two projected images cannot be completely overlapped. In particular, when the projection lens is a zoom lens, on the wide side, the projected image is distorted in a pincushion shape as shown by the solid line in FIG. 17A, and on the tele side, the projected image is barrel-shaped as shown by the solid line in FIG. 17B. Tend to be distorted. The broken lines in both figures are projection images when the projection lens has no distortion. Since the amount of axis shift of the projection lens (the distance from the center of the screen of the liquid crystal panel to the optical axis of the projection lens) differs between the two projection display devices, the pixel shift of the projected image at the wide end and the tele end is considerably large. There's a problem.

It is conceivable that the display image of the liquid crystal panel is distorted in advance by devising a drive circuit of the liquid crystal panel or introducing a signal processing circuit for deforming the image. However, since the liquid crystal panel has a pixel structure, the display image cannot be displayed in advance. Distortion causes a problem that fine characters and thin lines are not displayed correctly.

The present invention is directed to a projection image correction lens for reducing a pixel shift of a projection image when stack projection is performed using a plurality of projection display devices, a projection lens device using the projection image correction lens, and a projection display. It is intended to provide a device.

[0008]

In order to solve this problem, a projection image correction lens according to the present invention comprises a first lens disposed on an emission side of a projection lens of a projection display device, and
And a second lens disposed between the projection lens and the projection lens, a predetermined optical axis is az axis, a screen horizontal direction is an x axis,
Assuming that the vertical direction of the screen is the y-axis, the two lenses have different focal lengths in the xz plane and the yz plane, and the xz in the case of combining the two lenses is different.
The combined focal length in the plane and the combined focal length in the yz plane are longer than the optical path length from the projection lens to the screen,
The air gap between the two lenses is variable, and at least one of the lenses is configured so that the angle between its central axis and the z-axis is variable.

One of the two lenses is a plano-convex cylindrical lens, and the other is a plano-concave cylindrical lens. The convex bus line of the plano-convex cylindrical lens and the concave bus line of the plano-concave cylindrical lens are the same. Should be substantially parallel. The two lenses preferably have a convex cylindrical surface and a concave cylindrical surface facing each other, and the first lens is preferably a plano-convex cylindrical lens. It is desirable that both generatrixes of the cylindrical surfaces of the two lenses be substantially parallel to the y-axis.

When the focal length in a plane perpendicular to the generatrix of the plano-concave cylindrical lens is f _1x , and the focal length in a plane perpendicular to the generatrix of the plano-convex cylindrical lens is f _2x ,

[0011]

(Equation 2)

It is desirable that In the projection image correction lens of the present invention, both the first lens and the second lens are combined with a plano-concave cylindrical surface lens and a plano-convex cylindrical surface lens with the cylindrical surfaces facing each other and the generatrix substantially parallel to each other. In the first lens, the refractive index of the plano-concave cylindrical lens is higher than the refractive index of the plano-convex cylindrical lens, and in the second lens, the refractive index of the plano-concave cylindrical lens is lower than the refractive index of the plano-convex cylindrical lens.
You may comprise so that the generatrix of four cylindrical surfaces may become mutually substantially parallel. The generatrix of the four cylindrical surfaces may be substantially parallel to the y-axis.

At least one of the first lens and the second lens has a curvature radius of the concave cylindrical surface of the plano-concave cylindrical lens equal to a curvature radius of the convex cylindrical surface of the plano-convex cylindrical lens.
The concave cylindrical surface and the convex cylindrical surface may be joined.

In the projection image correcting lens according to the present invention, the first lens is fixed to the first frame, the second lens is fixed to the second frame, and the first frame and the second frame are fixed. A spring means is interposed between the first frame and the second frame.
It is preferable that the air gap between the first lens and the second lens can be partially changed by fixing with three screw bodies and independently rotating the three screw bodies. The three screw members may be driven by a motor.

A projection lens device according to the present invention includes a projection lens, and a projection image correction lens disposed on an emission side of the projection lens, and uses the above-described projection image correction lens as the projection image correction lens. is there. The projection image correction lens may be rotatable about an axis parallel to the optical axis of the projection lens. Further, when the focus of the projection lens is adjusted, it is preferable that the projection image correction lens does not move. The projection image correction lens may be detachable from the projection lens.

A projection display apparatus according to the present invention includes a light source, a light valve that receives light emitted from the light source and forms an optical image as a change in optical characteristics, and a light valve that receives light emitted from the light valve. A projection lens for projecting an image on a screen, and a projection image correction lens disposed on the emission side of the projection lens, wherein the projection image correction lens is used as the projection image correction lens. It is preferable that the projection image correction lens is configured to be rotatable around an axis parallel to the optical axis of the projection lens.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

(Embodiment 1) FIG. 1 shows a lens configuration of a projection image correction lens according to Embodiment 1 of the present invention. In FIG. 1, reference numeral 21 denotes a projection lens, 22 denotes a projection image, and 23 denotes a projection image. The first lens 24 is a second lens.

The projection image correction lens comprises a first lens 23 and a second lens 24 in order from the projection image 22 side, and is arranged on the emission side of the projection lens 21. The first lens 23 is a plano-concave cylindrical lens having a flat screen side surface 25 and a concave cylindrical surface on the projection lens 21 side surface. The second lens 24 has a convex cylindrical surface on the screen side surface 27 and the projection lens 2.
One side surface 28 is a flat plano-convex cylindrical lens. An xyz orthogonal coordinate system is defined in which a predetermined optical axis is the z-axis, the screen horizontal direction is the x-axis, and the screen vertical direction is the y-axis.

Table 1 shows specific numerical examples of the projection image correction lens in a standard state. r _ix and r _iy are the radius of curvature (mm) in the xz plane of the i-th surface from the projection image side, and y
The radius of curvature (mm) in the z plane, d _i is (i)
The distance (mm) to the +1) plane, n _j and v _j are the refractive index at the e-line of the j-th lens from the projection image side, e
Abbe number in the line. f _1x and f _2x are the focal length (mm) of the first lens 23 and the second lens 24 in the xz plane, respectively, and f _1y and f _2y are the first lens 2 respectively.
3. The focal length (mm) of the second lens 24 in the yz plane.

[0021]

[Table 1]

In the standard state, the generatrix of the concave cylindrical surface 26 and the generatrix of the convex cylindrical surface 27 are both parallel to the y-axis, and the two planes 25 and 28 are both perpendicular to the z-axis.

The air gap between the concave cylindrical surface 26 and the convex cylindrical surface 27 is variable between 0.1 mm and 5 mm. Both the first lens 23 and the second lens 24 have outer dimensions of 80
mm × 80 mm. Each of the two lenses 23 and 24 has an antireflection film deposited on an effective area on both surfaces.

FIGS. 2 and 3 show the overall configuration of the projection image correction lens. FIG. 2 is a cross-sectional view taken along the vertical direction of the screen, and FIG. 3 is a view taken obliquely from the screen side. The first lens 23 is fixed to the frame 31, and the second lens 24 is fixed to the frame 32. The frame 31 is provided with through holes 33 at three locations, and the frame 32 is provided with three screw holes 34 at positions corresponding to the through holes 33.
Three adjusting screws 35a, 35b, and 35c pass through the through hole 33 and the coil spring 36, and are attached to the screw holes 34. The two adjustment screws 35a and 35b are symmetric about the main plane 37 of the first lens 23, and the remaining adjustment screws 35c are located on the main plane 37. By rotating the three adjusting screws 35a, 35b, 35c, the three adjusting screws 35a, 3 of the two frame bodies 31, 32 are rotated.
The intervals around 5b and 35c can be changed.

As shown in FIG. 2, the frame 32 is attached to a cylindrical body 38 having a circular window, and is rotatable with respect to the cylindrical body 38. The cylindrical body 38 is attached to the exit side end of the lens barrel of the projection lens.

The operation of the projection image correction lens of the present invention will be described below. First, the basic concept of the present invention will be described.

A theoretical analysis of the configuration of the stack projection shown in FIG. 16 shows that when the distortion of the projection lenses 3 and 12 is large, the aspect ratio of each projected image (the ratio of the vertical width to the horizontal width). Was slightly different from the aspect ratio of the image displayed on the liquid crystal panel, and the trapezoidal distortion rates of the two projected images were slightly different. Therefore, in the present invention, by arranging a projection image correction lens having an operation of slightly changing the aspect ratio of the projection image and an operation of slightly changing the vertical trapezoidal distortion on the emission side of the projection lens, a plurality of projection images can be obtained. The pixel shift between them is reduced.

Here, it is assumed that there is a rectangular projection image (ideal projection image) without graphic distortion on the screen, and light is emitted from this projection image and enters the projection image correction lens, and the projection image correction lens Form a virtual image corresponding to the ideal projection image. Since the virtual image corresponds to the projection image formed only by the projection lens, if the projection image only by the projection lens matches the virtual image,
When the projection image correction lens is arranged on the emission side of the projection lens and projected, the image is a rectangular image with no graphic distortion.

The operation of the aspect ratio correction of the projection image correction lens will be described. As shown in FIG. 1, consider an xyz orthogonal coordinate system in which the optical axis of the projection lens combined with the projection image correction lens is the z axis, the screen vertical direction is the x axis, and the screen horizontal direction is the y axis. The first lens 23 is a thin cylindrical lens with negative power, the second lens 24 is a thin cylindrical lens with positive power, and each generatrix is parallel to the y-axis. First lens 23
The focal length in the xz plane is f _1x , the focal length in the yz plane is f _1y = ∞, the focal length of the second lens 24 in the xz plane is f _2x , the focal length in the yz plane is f _2y = ∞, The air gap between the first lens 23 and the second lens 24 is d, and the distance from the ideal projection image 41 to the first lens 23 is s.

FIG. 4 shows an optical path diagram in the yz plane. Since both the first lens 23 and the second lens 24 have a focal length of ∞ in the yz plane and a center thickness of 0, the ideal projection image 41
The light beam emitted in an arbitrary direction from an arbitrary object point 42 travels straight through the first lens 23 and the second lens 24 to form a virtual image 43
Is formed at exactly the same position as the ideal projected image 41. Accordingly, the distance from the second lens 24 to the Gaussian image plane in the yz plane of the virtual image image s _y 'When, s _y'
= −s−d. Further, even if the air interval d is changed, the size of the virtual image 43 is the same as the size of the ideal projection image 41.

FIG. 5 shows an optical path diagram of an axial ray in the xz plane. The distance from the second lens 24 to the virtual image in the xz plane is s _x ′.

By paraxial tracking, s _x 'can be expressed as follows.

[0033]

(Equation 3)

[0034] In this case, xz of f _x is the projected image correction lens
This is the composite focal length in a plane, and can be expressed as follows.

[0035]

(Equation 4)

If the position of the virtual image in the xz plane is far from the position of the virtual image in the yz plane, astigmatism will also exist on the optical axis 44. This astigmatic difference does not need to be exactly 0, but needs to be reduced to such an extent that there is no practical problem. To do so, the xz
The distance to the virtual image in the plane needs to be s _x '≒ -s-d.

From _equation (3), the condition for s _x '≒ -s-d is as follows.

[0038]

(Equation 5)

[0039]

(Equation 6)

[0040]

(Equation 7)

From _equation (5), it is ideal to make the combined focal length fx in the xz plane sufficiently longer than the projection distance s in order to reduce the astigmatic difference of the projected image. actually,
At least, it is necessary to be longer than the combined focal length f _x the projection distance s in the xz plane.

In order to satisfy the condition of (Equation 5), f _x =
Considering the case of ∞, from (Equation 4),

[0043]

(Equation 8)

Is derived. When (Equation 8) is combined with (Equation 6) and (Equation 7),

[0045]

(Equation 9)

Is derived. Next, an off-axis principal ray in the xz plane will be discussed. Here, it is assumed that the position of the virtual image image 43 is the same as the position of the ideal projection image 41, and the optical axis 4 of the object point 42 on the ideal projection image 41 as shown in FIG.
The distance from 4 h _0, the distance t from the first lens 23 to the pupil center 46 of the projection lens, the virtual image picture on the xz plane 43
The distance from the optical axis 44 of the image point 47 of the upper and h _3.

By paraxial tracking, h ₃ / h ₀ can be expressed as follows.

[0048]

(Equation 10)

(Equation 8) is f _x ≫t, so that the second
Since the term is negligible and d≪s, d of s + d in the third term on the right-hand side can be ignored, and can be approximated as follows.

[0050]

[Equation 11]

F _1x <0, f _2x > 0, f _1x ≒ −f _2x , t
Considering that <s, the second right-hand side of (Equation 11)
Since the term is positive, from (Equation 11), d in the xz plane
It can be seen that as the _{value of} h increases, h ₃ / h ₀ decreases.
As described above, when d is changed in the xz plane, the size of the virtual image changes. On the other hand, as described above, the size of the virtual image does not change even if d is changed in the yz plane. Therefore,
By changing d, the aspect ratio of the virtual image 43 can be changed. Since the aspect ratio only needs to be changed slightly, the change in the air gap d is small.

Since the virtual image 43 corresponds to the projected image when the projection is performed using only the projection lens, if the horizontal width of the virtual image 43 becomes shorter than the ideal projected image 41 when the air interval d is increased, the projected image 43 When the correction lens is disposed on the emission side of the projection lens to increase the air gap d, the horizontal width of the projection image increases.

By arranging the projection image correction lens on the exit side of the projection lens in this way, the horizontal width of the screen can be slightly increased without substantially changing the vertical width of the projection image. That is, the aspect ratio of the projected image can be adjusted. However, it should be noted that if d becomes too large, the conditions of (Equation 6) and (Equation 7) do not hold, and the astigmatic difference increases, so that the resolution of the projected image decreases.

Next, the operation of the trapezoidal distortion correction of the projection image correction lens will be described. Here, the correction of the vertical trapezoidal distortion will be described. As shown in FIG. 7, the first lens 2
3 is slightly rotated about an axis parallel to the x-axis.

In the configuration shown in FIG. 7, the ideal projected image 41
The air distance d is longer for the light beam emitted from the upper object point 48 toward the pupil center 46, and the light beam emitted from the lower object point 49 toward the pupil center 46 of the ideal projected image 41 is air The interval d is short. As described above, the projection image correction lens increases the ideal air gap 41 by increasing the air distance d.
Has the effect that the vertical width of the screen of the virtual image corresponding to the image does not change and the horizontal width of the screen becomes shorter.
As shown in FIG. 8, the upper side 51 becomes shorter and the lower side 52 becomes
Becomes longer. Since the first lens 23 and the second lens 24 are symmetric with respect to the yz plane, the virtual image 43 is also symmetric with respect to the yz plane. Therefore, by disposing the projection image correction lens on the emission side of the projection lens and rotating the first lens 23 about an axis parallel to the x-axis, vertical trapezoidal distortion of the projection image can be corrected.

The second lens 24 may be rotated about an axis parallel to the x-axis, or the first lens 23 and the second lens 24 may be rotated about an axis parallel to the x-axis. The vertical trapezoidal distortion of the projected image can be corrected.

When the projection image correction lens 23 is rotated about the z-axis from the configuration shown in FIG. 7, the virtual image corresponding to the ideal projection image 41, which is a rectangle, becomes a parallelogram as shown in FIG. . This can be understood by considering that the projection image correction lens does not change the dimension in the generatrix direction of the cylindrical lens, but changes the dimension in the direction perpendicular to the generatrix. By utilizing this effect, when a parallelogram distortion exists in the projection image, the parallelogram distortion can be reduced by rotating the projection image correction lens about the z-axis.

The correction of the parallelogram distortion is performed by the second lens 24.
Is rotated about the z-axis or the first lens 2
It is also possible to rotate the third and second lenses 24 about the z-axis. When adjusting the parallelogram distortion, the first lens,
The second lens or two lenses may be rotated around an axis parallel to the z-axis.

When stack projection is performed with the configuration shown in FIG. 1, the liquid crystal panel, the projection lens, the projection image correction lens, and the screen are arranged symmetrically with respect to the yz plane. Although no distortion should occur, the symmetry with respect to the yz plane may slightly deviate due to an assembly error. In this case, a slight parallelogram distortion occurs.

In the projection image correction lens shown in FIGS. 2 and 3, three adjustment screws 35a, 35b, 35c are turned by turning three adjustment screws 35a, 35b, 35c, respectively.
Since the distance around c can be changed, the aspect ratio of the projected image can be corrected by turning the three adjustment screws 35a, 35b, and 35c equally, and the first lens 23 can be rotated by turning only the adjustment screw 35c. When the frame rotates with respect to the cylindrical body 38, the parallelogram distortion can be corrected. It is necessary to slightly change the size of the projected image, but if the projection lens is a zoom lens, it may be adjusted by rotating the zoom ring.If the projection lens is a fixed focus lens, the resolution may be slightly Although it is lowered, it is enough to turn the focus ring slightly.

In the configuration shown in FIGS. 1 and 2, each of the two cylindrical lenses 22 and 23 has a flat surface opposite to the cylindrical surface, for the following reason. A lens having both cylindrical surfaces requires the generatrix of the two cylindrical surfaces to be parallel to each other, but such a lens cannot be easily processed. If the parallelism between the two generatrixes is not good, the aberrations resulting therefrom degrade the resolution of the projected image. Therefore, if one of the surfaces is a flat surface, it is not necessary to consider the direction of the generatrix, so that the problem of resolution degradation is avoided.

The reason why the concave cylindrical surface and the convex cylindrical surface are opposed to each other as shown in FIGS. 1 and 2 is as follows.

A cylindrical lens having a convex surface is polished by attaching a lens material to the side surface of a cylinder, arranging a polishing dish around the lens material, and reciprocating along a central axis while rotating the cylinder. In addition, a cylindrical lens having a concave surface is polished by replacing a lens material with a polishing plate in the same manner. The radius of curvature of the cylindrical surface is approximately equal to the radius of the cylinder. When the diameter of the cylinder becomes large, it becomes difficult to secure the surface accuracy of the cylindrical surface, and in order to increase the size of the device,
Processing costs increase. Therefore, there is a limit in increasing the radius of curvature of the cylindrical surface, and it is difficult to produce a cylindrical lens having a long focal length.

The focal length f _x of the first lens in the xz plane and the focal length f _y of the second lens in the xz plane can be expressed by the following equations.

[0065]

(Equation 12)

[0066]

(Equation 13)

Since the radius of curvature of the cylindrical surface cannot be increased,
The focal length f _x of the first lens and the focal length f _{y of} the second lens
Can not be too long. Considering this situation, it is necessary to make d very small to satisfy the conditions of (Equation 6) and (Equation 7).

In the description of the operation of the projection image correction lens, the first lens 23 and the second lens 24 are thin cylindrical lenses. However, the center thickness of an actual cylindrical lens is not zero. However, assuming that the air interval d is the interval between the opposite principal points, the conclusion derived as a thin lens can be used as it is.

The center thickness of the first lens 23 is d₁ , The refractive index
n₁ Then, as shown in FIG. 10A, the plane-side principal point
H₁ Is d from the plane 25₁/ N₁ Only advanced point
And the cylindrical surface side principal point H₁′ Is located at the vertex of concave cylindrical surface 26
I do. The center thickness of the second lens 24 is d_Two , The refractive index n_Two When
Then, as shown in FIG. 10 (b), the cylindrical surface side principal point H _Two
Is located at the vertex of the convex cylindrical surface 27, and the plane-side principal point H_Two′ Is flat
D from the surface 28_Two/ N_Two Located just advanced point.

There are eight possible arrangements of the first lens 23 and the second lens 24 as shown in FIG. Of the eight types, when the air gap between the two lenses is minimized, the principal point interval can be minimized when the concave cylindrical surface and the convex cylindrical surface are opposed to each other. Since the interval between the concave cylinder and the convex cylindrical surface can be made substantially zero, the principal point interval can be made substantially zero. When the two cylindrical surfaces are not opposed to each other, the principal point interval is longer than the air interval, so that the principal point interval cannot be made substantially zero.

The concave cylindrical surface and the convex cylindrical surface of the projection image correction lens preferably have an incident angle at which an off-axis chief ray passes as small as possible in order to reduce off-axis aberrations. For this purpose, the concave cylindrical surface of the first lens 23 may be directed toward the projection lens, and the convex cylindrical surface of the second lens 24 may be directed toward the screen.

For this reason, the projection image correction lens has the plano-concave cylindrical surface 26 and the plano-convex cylindrical surface 27 facing each other,
The lens 23 faces the screen toward the screen, and the second lens 2
4 preferably has the convex cylindrical surface facing the screen.

[0073] The focal length f ₁ of the first lens 23, a description will be given of the relationship between the focal length f ₂ of the second lens 24.

In order to reduce the astigmatic difference of the virtual image with respect to the ideal projected image, as described above, (Equation 5) to (Equation 7)
Needs to be satisfied. (Equation 6) and (Equation 7) make the air distance d as short as possible, and set the focal length of the first lens 23 to |
f ₁ | and indicates that it is necessary to increase as much as possible and the focal length f ₂ of the second lens 24. Also, (Equation 5)
(8) needs to be almost satisfied to satisfy
(Equation 9) needs to be satisfied.

To correct vertical trapezoidal distortion of the projected image,
In consideration of inclining at least one lens, it is necessary to slightly separate the two lenses, and the air gap d needs to be 0 or more. Considering d ≧ 0 and (Equation 8), f ₂ ≧ | f ₁ | must be satisfied.

Considering the above, the first lens 2
The focal length f ₁ of 3, while changing the relationship between the focal length f ₂ of the second lens 24 and a simulation of astigmatism, it has been found that the following procedures may be used.

[0077]

[Equation 14]

If the condition of (Equation 14) is not satisfied, the astigmatic difference becomes large, causing a problem that the resolution of the projected image is reduced by the projected image correcting lens.

As described above, the projection image correction lens shown in FIG. 1 can correct the aspect ratio and the trapezoidal distortion of the projected image, and can also correct the parallelogram distortion. Therefore, when stack projection is performed by arranging two projection type display devices one above the other, the projection image correction lenses shown in FIG. 1 are respectively arranged on the emission sides of the two projection lenses, and the light of the projection image correction lens is If the adjustment is performed by the rotation around the axis and the rotation of the three adjustment screws, the above operation can reduce the pixel shift between the two projected images.

(Embodiment 2) FIG. 12 shows a stack type projection display apparatus according to Embodiment 2 of the present invention. In FIG. 12, reference numerals 61 and 62 denote projection display apparatuses, and 67 and 68. Is a projection lens, and 71 and 72 are projection image correction lenses.

Two projection display devices 61 and 62 are placed on a lower plate 64 and an upper plate 65 of a gantry 63, respectively. The gantry 63 has a lower plate 64 and an upper plate 65 parallel to each other attached to a frame 66 made of an iron pipe. 2
The projection type display devices 61 and 62 are placed on the lower plate 63 and the upper plate 64, respectively, so that the two projection lenses 67 and 68 are parallel to each other for adjusting the elevation angle of the projection type display devices 61 and 62. Adjust the height of the legs 69, 70. In the two projection display devices 61 and 62, each of the projection lenses 67 and 68 is movable in the vertical direction of the screen, and as shown in FIG. 16, the light of the projection lens 67 of the lower projection display device 61 is reduced. The axis can pass through the center of the lower end of the projected image.

The superposition of two projected images is performed as follows. A cross hatch video signal is input to the two projection display devices 61 and 62, the focus of the projection lens 67 of the lower projection display device 61 is adjusted, and the projection lens 67 is moved in the vertical direction of the screen and zoomed. The adjustment is performed so that the projected image fits within the frame of the screen. The focus of the projection lens 68 of the upper projection image display device 62 is adjusted, and the projection lens 68 is further moved in the screen vertical direction,
The zoom adjustment and fine movement of the projection display device 62 itself on the upper plate 65 change the projection image to the lower projection display device 6.
1 so as to substantially overlap the projected image.

Next, the projection image correction lenses 71 and 72 are attached to the two projection lenses 67 and 68, respectively, and the three adjustment screws 7 of the projection image correction lenses 71 and 72 are respectively used.
With the rotation of 3, 74 and the rotation of the entire projection image correction lenses 71, 72, the shift of the cross hatch between the two projection images is reduced while changing the aspect ratio, vertical trapezoidal distortion, and parallelogram distortion of the two projection images. Adjust so that

As described above, the projection image correction lens can change the aspect ratio, trapezoidal distortion, and parallelogram distortion. Therefore, by using the projection image correction lens, the pixel shift between the two projection images can be reduced. can do.

In the case where the above adjustments are made, if two cross hatches are of the same color, it is difficult to distinguish which projection type display device each cross hatch is.
It is preferable to change the color of the cross hatch projected by the two projection display devices. For example, adjustment is easy if the lower projection display device projects a green cross hatch and the upper projection display device projects a red cross hatch.

FIG. 12 shows two projection lenses 67 and 68.
Although the configuration in which the projection image correction lenses 71 and 72 are respectively arranged on the emission side of the above is shown, pixel displacement between the two projection images may be reduced even if one of the projection image correction lenses is omitted. Further, when only one projection display device is used, the projection image correction lens is unnecessary, and therefore, it is preferable that the projection image correction lens be detachable from the projection lens.

FIG. 13 shows a configuration of a projection type display device used in the stack type projection type display device shown in FIG. FIG.
3 is a plan view, in which the horizontal direction of the screen of the projection image is parallel to the paper surface. The projection display device shown in FIG. 13 has the projection image correction lens shown in FIGS. 1 to 3 arranged on the emission side of the projection lens of the projection display device.

Lamp 81, concave mirror 82, filter 83
Thus, the light source 84 is configured. The lamp 81 is a metal halide lamp. The concave mirror 82 is an elliptical mirror, and is formed by depositing an optical multilayer film that reflects visible light and transmits infrared light on the inner surface of a glass substrate. Filter 83
An optical multilayer film that transmits visible light and reflects infrared light and ultraviolet light is deposited on one surface of a glass substrate, and an antireflection film is deposited on the other surface. The lamp 81 is arranged such that the center of the light emitter is located at the first focal point 85 of the elliptical mirror 82, and a filter 83 is arranged on the emission side of the concave mirror 82. Light emitted from the lamp 81 is reflected by the reflecting surface of the concave mirror 82, and an image of the luminous body is formed at the second focal point. The light emitted from the concave mirror 82 passes through the filter 83 to remove infrared light and ultraviolet light.

The light emitted from the light source 84 is
After that, the light is incident on a color separation optical system including a blue transmission dichroic mirror 87, a green reflection dichroic mirror 88, and a plane mirror 89, and is decomposed into red, green, and blue primary color lights. The red primary color light is incident on a relay optical system including a first relay lens 90, a second relay lens 91, and two plane mirrors 92 and 93. The blue and green primary color lights emitted from the color separation optical system and the red primary color light emitted from the relay optical system are respectively divided into field lenses 94, 95,
96, after passing through the incident side polarizing plates 97, 98, 99, the light enters the liquid crystal panels 100, 101, 102. Concave mirror 8
The second focal point 2 is located near the liquid crystal panels 100 and 101. Each of the liquid crystal panels 100, 101,
Although the light path length up to 102 is longer than the other light paths by the red light path, the two relay lenses 90 and 91 converge the light that is about to diverge to the inside, so that even if the light path length is long, the light is red. It is efficiently transmitted to 102.

Each of the liquid crystal panels 100, 101, and 102 is a TN liquid crystal panel, and forms an optical image as a change in polarization state according to a video signal. Liquid crystal panel 100,
The outgoing light from 101 and 102 passes through the outgoing-side polarizing plates 103, 104 and 105, respectively, and then enters the color combining prism 106. The color combining prism 106 is formed by joining four triangular prisms, and a red reflecting dichroic multilayer film and a blue reflecting dichroic multilayer film are vapor-deposited so as to intersect in an X-shape on the slope of the triangular prism forming the joining surface. Things. Each primary color light that has entered the color combining prism 106 is combined into one light by the color combining prism 106, and then enters the projection lens 107.

The projection lens 107 is a zoom lens having good telecentricity, and can move in parallel in the vertical direction of the screen. Since the projection lens 107 can be moved up and down, the projection display device can be arranged below or above the center of the screen of the projection image so that the projection display device does not block the projection image. It is easy to adjust the projected image to fit in the maximum size.

At the screen side end of the projection lens 107,
A projection image correction lens 108 is mounted. The projection image correction lens 108 is the same as that shown in FIGS. 1 to 3. A plano-concave cylindrical lens 109 is arranged on the screen side, and a plano-convex cylindrical lens 110 is arranged on the projection lens side. , 112 are facing each other. LCD panel 10
The optical images formed at 0, 101, and 102 are enlarged and projected on a screen by a projection lens 107 and a projection image correction lens.

In the above description, the projection type display using the liquid crystal panel as the light valve has been described.
Instead of the liquid crystal panels 100, 101, and 102, any light valve having a pixel structure and forming an optical image as a change in optical characteristics can be used. The number of light valves may be one.

(Embodiment 3) FIG. 14 shows a projection lens apparatus according to Embodiment 3 of the present invention. In FIG. 14, reference numeral 121 denotes a projection lens, and 122 denotes a projection image correction lens.

The projection lens device shown in FIG. 14 is a combination of a projection lens 121 and a projection image correction lens 123 on the exit side.

The projection lens 121 is a zoom lens, and includes a focus lens 123, a variator 124, a compensator 125, and a master lens 126. The focus state of the projected image can be adjusted by moving the focus lens 123 along the optical axis 127, and the screen size of the projected image can be adjusted by moving the variator 124 and the compensator 125 along the optical axis 127 according to a predetermined rule. Can be changed. Focus lens 123,
Even if the variator 124 and the compensator 125 are moved, the projection image correction lens 122 does not rotate.

The projection image correction lens 122 is the same as that shown in FIGS. 1 to 3, and can rotate about the optical axis 127. When the three adjustment screws 35a, 35b, 35c of the projection image correction lens 122 are rotated,
The aspect ratio and trapezoidal distortion of the projected image can be changed.

The three adjusting screws 35a, 35b, 35c may be independently rotated by three motors for adjustment. Further, the adjustment may be performed by rotating the entire projection image correction lens 122 by a motor. In this case, for example, when the projection display device is arranged at a high position,
This is convenient when the projection display device is installed in a place that cannot be easily accessed by a person who adjusts the projection display device.

(Embodiment 4) Table 2 shows specific numerical examples of the lens configuration of the projection image correction lens according to Embodiment 4 of the present invention. r _ix and r _iy are the radius of curvature (mm) of the ith plane in the xz plane and the radius of curvature (m) in the yz plane, respectively.
m), d _i is the interval from the i-th surface to the (i + 1) th surface (m
m), n _j and v _j are the refractive index and Abbe number of the j-th lens at e-line, respectively. f _1x and f _2x are the focal lengths (mm) of the first lens L ₁ and the second lens L _{2 in} the xz plane, respectively, and f _1y and f _2y are the first lens L ₁ and the second lens L ₂ , respectively. Focal length in yz plane (mm)
It is.

[0100]

[Table 2]

The projection image correction lens shown in Table 2 has the same configuration as the projection image correction lens shown in FIG.
The curvature radius of the convex cylindrical surface of the second lens is changed to 300 mm. That is, the curvature radii of the cylindrical surfaces of the two cylindrical lenses are the same.

The projection image correction lens shown in Table 2 is equivalent to a glass plate having two parallel surfaces when the air gap is set to 0, and its thickness is very short compared to the projection distance. The ratio can be considered as unchanged at all. If the air gap is in the range of 0 to 4 mm, the astigmatic difference of the projection image correction lens is at a level that does not cause any practical problem.

In this case as well, the aspect ratio, trapezoidal distortion, and parallelogram distortion of the projected image can be adjusted as in the case of the projected image correcting lens in the first embodiment.

(Embodiment 5) FIG. 15 shows the configuration of a projection image correction lens according to Embodiment 5 of the present invention. In FIG. 15, reference numeral 131 denotes a first lens, and 132 denotes a second lens. .

The projection image correction lens shown in FIG. 17 includes a first lens 131 and a second lens 1 in order from the screen side.
32.

The first lens 131 is formed by joining a plano-concave cylindrical lens 133 having a flat surface toward the screen and a plano-convex cylindrical lens 134 having a convex cylindrical surface facing the screen. The second lens 132 is formed by joining a plano-concave cylindrical lens 135 having a flat surface toward the screen and a plano-convex cylindrical lens 136 having a convex cylindrical surface facing the screen.

Table 3 shows specific numerical examples. r _ix , r _iy
Are the radii of curvature (mm) in the xz plane of the i-th surface, and y
The radius of curvature (mm) in the z plane, d _i is (i)
+1) spacing to the plane (mm), n _j and v _j are j-th
The refractive index and Abbe number at the e-line of the second lens.
f _1x and f _2x are respectively the focal length (mm) of the first lens 131 and the second lens 132 in the xz plane, f _1y , f
_2y is a first lens 131 and a second lens 132, respectively.
Is the focal length (mm) in the yz plane.

[0108]

[Table 3]

Four cylindrical surfaces 137, 138, 139, 1
The curvature radii of all 40 are 150 mm. The first lens 131 sets the refractive index of the plano-concave cylindrical lens 133 higher than the refractive index of the plano-convex cylindrical lens 134, and the second lens 132 sets the refractive index of the plano-concave cylindrical lens 135 to the plano-convex cylindrical lens 1
The refractive index is lower than 36. Therefore, the power of the first lens 131 is negative and the power of the second lens 132 is positive.

Next, the cemented cylindrical lens will be described. The focal length of a plano-convex cylindrical lens having a cylindrical surface with a radius of curvature of r and a refractive index of n can be expressed by the following equation.

[0111]

(Equation 15)

Next, in a lens in which a plano-concave cylindrical lens and a plano-convex cylindrical lens having the same radius of curvature of the cylindrical surface are joined with their cylindrical surfaces facing each other, the refractive index of the plano-concave cylindrical lens is n ₁ ,
Assuming that the refractive index of the plano-convex cylindrical lens is n ₂ and the radius of curvature of the two cylindrical surfaces is r, the composite focal length f can be expressed as follows.

[0113]

(Equation 16)

By comparing (Equation 15) and (Equation 16),
It can be seen that, even if the radius of curvature of the cylindrical surface is short, if the difference between the refractive indices of the two cylindrical lenses is small, the combined focal length can be very long.

As described above, if the first lens 131 and the second lens 132 are cemented cylindrical lenses, even if the radius of curvature of the cylindrical surface is short, the composite focal point can be obtained by utilizing a slight difference in the refractive index. The distance can be very long.
In addition, if the radius of curvature of the cylindrical surface is short, it is easy to ensure the surface accuracy of the cylindrical surface.

The radius of curvature of the plano-concave cylindrical lens of the first lens 131 and the radius of curvature of the plano-concave cylindrical lens of the second lens 132 are matched, and the radius of curvature of the plano-convex cylindrical lens of the first lens 131 is And the radius of curvature of the plano-convex cylindrical lens of the second lens 132 may be matched. Then, since the apparatus and jig for processing the cylindrical surface are common, the processing cost is reduced accordingly.

Note that, in the configuration shown in FIG.
For one of the lens 131 and the second lens 132,
The two cylindrical lenses may be separated.

The projection image correction lens shown in FIG. 15 can also slightly change the aspect ratio and vertical trapezoid distortion of the projection image.

[0119]

As described above, according to the present invention, a bright projection image can be obtained by using a plurality of projection display devices, and the aspect ratio and trapezoid of the projection image can be obtained by introducing a projection image correction lens. Since distortion can be adjusted, a projected image with less pixel shift can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a lens configuration of a projection image correction lens according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating an overall configuration of a projection image correction lens according to Embodiment 1 of the present invention.

FIG. 3 is a perspective view showing a configuration of a projection image correction lens according to Embodiment 1 of the present invention.

FIG. 4 is a diagram for explaining the operation of the projection image correction lens in the yz plane.

FIG. 5 is a diagram for explaining the effect of a projection image correction lens on an axial ray in the xz plane.

FIG. 6 is a diagram for explaining the effect of the projection image correction lens on an off-axis principal ray in the xz plane.

FIG. 7 is a diagram for explaining the operation when the first lens of the projection image correction lens is rotated in the yz plane.

FIG. 8 is a diagram for explaining a state of a virtual image when the first lens of the projection image correction lens is rotated in the yz plane.

FIG. 9 is a diagram for explaining the operation when the first lens of the projection image correction lens is rotated about the z axis.

FIG. 10 is a diagram for explaining positions of principal points of a first lens and a second lens.

FIG. 11 is a diagram for explaining eight configurations regarding the arrangement of a first lens and a second lens.

FIG. 12 shows a projection display apparatus according to a second embodiment of the present invention.
Schematic configuration diagram showing the configuration of a projection display device arranged above and below a table

13 is a schematic configuration diagram showing the configuration of one projection display device shown in FIG.

FIG. 14 is a schematic configuration diagram illustrating a configuration of a projection lens device according to a third embodiment of the present invention;

FIG. 15 is a schematic configuration diagram showing a configuration of a projection image correction lens according to a fifth embodiment of the present invention.

FIG. 16 is a schematic configuration diagram showing a configuration when stack projection is performed using two projection display devices.

FIG. 17 is a diagram showing an example of figure distortion due to distortion of a projection lens used in a projection display device.

[Explanation of symbols]

 21 Projection lens 23, 109, 131 First lens 24, 110, 132 Second lens 26 Concave cylindrical surface 27 Convex cylindrical surface 31, 32 Frame 61, 62 Projection display device 63 Mount 67, 68, 107, 121 Projection lens 72, 73, 122 Projected image correction lens 81 Lamp 82 Concave mirror 87, 88 Dichroic mirror 90, 91 Relay lens 94, 95, 96 Field lens 97, 98, 99 Incident side polarizing plate 100, 101, 102 Liquid crystal panel 103, 104, 105 Emission-side polarizing plate 106 Color synthesis prism

Claims (20)

[Claims] A first lens disposed on an emission side of a projection lens of a projection display apparatus; and a second lens disposed between the first lens and the projection lens. When the optical axis is the z-axis, the screen horizontal direction is the x-axis, and the screen vertical direction is the y-axis, each of the two lenses has a different focal length in the xz plane and a different focal length in the yz plane. The combined focal length in the xz plane and the combined focal length in the yz plane when the lenses are combined is longer than the optical path length from the projection lens to the screen, and the air gap between the two lenses is variable. One lens is a projection image correction lens in which the angle between the center axis and the z axis is variable. 2. The two lenses, one of which is a plano-convex cylindrical lens, the other of which is a plano-concave cylindrical lens, wherein the generatrix of the convex surface of the plano-convex cylindrical lens and the concave surface of the plano-concave cylindrical lens are 2. The projection image correction lens according to claim 1, wherein the generatrix is substantially parallel to the generatrix. 3. The first lens is a plano-concave cylindrical lens,
3. The projection image correction lens according to claim 2, wherein the second lens is a plano-convex cylindrical lens. 4. The projection image correction lens according to claim 2, wherein the cylindrical surface of the first lens and the cylindrical surface of the second lens face each other. 5. The generatrix of each of the cylindrical surfaces of the two lenses is y.
The projection image correction lens according to claim 2, wherein the projection image correction lens is substantially parallel to the axis. 6. When the focal length in a plane perpendicular to the generating line of the plano-concave cylindrical lens is f _1x , and the focal length in a plane perpendicular to the generating line of the plano-convex cylindrical lens is f _2x , The projection image correction lens according to any one of claims 2 to 5, wherein 7. The projection image correction lens according to claim 1, wherein one of the two lenses is rotatable with respect to the other about an axis parallel to the z-axis. 8. The first lens and the second lens are each a combination of a plano-concave cylindrical lens and a plano-convex cylindrical lens with their cylindrical surfaces facing each other and the generatrix substantially parallel to each other. In the first lens, the refractive index of the plano-concave cylindrical lens is higher than the refractive index of the plano-convex cylindrical lens, and in the second lens, the refractive index of the plano-concave cylindrical lens is lower than the refractive index of the plano-convex cylindrical lens. 2. The generatrix of four cylindrical surfaces being substantially parallel to each other.
The projection image correction lens described in the above. 9. The projection image correcting lens according to claim 8, wherein all generatrixes of the four cylindrical surfaces are substantially parallel to the y-axis. 10. A lens having at least one of a first lens and a second lens, wherein a radius of curvature of a concave cylindrical surface of a plano-concave cylindrical lens is equal to a radius of curvature of a convex cylindrical surface of a plano-convex cylindrical lens.
The projection image correction lens according to claim 8, wherein the concave cylindrical surface and the convex cylindrical surface are joined. 11. A first lens is fixed to a first frame, a second lens is fixed to a second frame, and a spring is provided between the first frame and the second frame. With the means interposed therebetween, the first frame and the second frame are fixed with three screws, and the first and second lenses are independently rotated by rotating the three screws independently. 9. The projection image correction lens according to claim 1, wherein an air space between the two lenses is partially variable. 12. The projection image correction lens according to claim 11, wherein said three screw members are driven by a motor. 13. A projection image correction lens according to claim 1, further comprising a projection lens, and a projection image correction lens disposed on an emission side of said projection lens. Projection lens device. 14. The projection lens device according to claim 13, wherein the projection image correction lens is rotatable around an axis parallel to an optical axis of the projection lens. 15. The projection lens device according to claim 13, wherein the projection image correction lens is not moved when the focus of the projection lens is adjusted. 16. The projection lens device according to claim 13, wherein the projection image correction lens is detachable from the projection lens. 17. A light source, a light valve that receives light emitted from the light source and forms an optical image as a change in optical characteristics, and light emitted from the light valve enters to project the optical image on a screen. A projection lens, and a projection image correction lens disposed on the emission side of the projection lens,
A projection display device, wherein the projection image correction lens is the projection image correction lens according to any one of claims 1 to 12. 18. The projection display device according to claim 17, wherein the projection image correction lens is rotatable about an axis parallel to an optical axis of the projection lens. 19. A plurality of projection type display devices are arranged in a parallel movement relationship, and at least one of the projection type display devices is provided with a projection image correction lens on an emission side of a projection lens. A projection display device, wherein the projection image correction lens is the projection image correction lens according to any one of claims 1 to 12. 20. Two projection display devices are vertically arranged so as to have a parallel movement relationship, a projection image correction lens is fixed to a corresponding projection lens, and each projection lens is translated in a vertical direction of the screen. 20. The projection display device according to claim 19, wherein: