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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a projector such as a video projector, a liquid
crystal projector or the like, and particularly to a projector for
projecting images of image forming means, which correspond to the colors
of, for example, B (blue), G (green) and R (red), onto a screen in an
overlapping fashion to form a composite multicolor image.
2. Description of the Prior Art
FIG. 71 shows the optical system of a conventional projector.
The projector in FIG. 71 has image forming means 1, 2, 3 such as a liquid
crystal display (hereinafter referred to as the "LCD") or as a CRT. charts
form pictures, and projecting lenses 4, 5 and 6 having optical axes Ax1,
Ax2, Ax3 are perpendicular to each image forming means. The chart 1 and
the lens 4 comprise a projecting optical system A. The chart 2 and the
lens 5, the chart 3 and the lens 6 comprise projecting optical systems B,
C. In FIG. 71, principal rays emitting from three points of each image
forming means are shown.
The optical axis Ax2 of the central projecting lens 5 is perpendicular to a
screen 7 onto which images are projected, while the optical axes Ax1, Ax3
of the projecting lenses 4, 6 intersect with the optical axis Ax2 of the
projecting lens 5 on the screen and are not perpendicular to the screen 7.
It is defined here that the optical axis Ax2 is the x-axis, the crossline
between a plane including three optical axes and the screen is the y-axis,
and the direction perpendicular to the y-axis on the screen is the z-axis.
FIG. 72 shows an optical path of the projecting optical system C of FIG.
71. The luminous flux as shown in this Figure is converged most in the
projecting lens 6.
However, the above-mentioned conventional projector has problems since
images formed by the projecting optical systems A, C are angled with
respect to the screen. As a result, distortion is generated and a focus
error of an image is generated in the peripheral portion in the y-axis
direction.
Next, the degree of focus error in the above-mentioned construction, will
be described concretely by applying concrete numerical figures.
The image forming means is an LCD of three inches size. The display area is
about 46 mm.times.61 mm. The LCD is provided on the periphery of the
display area with a lead frame or a substrate for mounting a drive IC. In
this example, the substrate measures 160 mm in the width direction. When,
therefore, the LCDs are arranged side by side as shown in FIG. 71, the
distance between the centers of the adjacent LCDs is a minimum of 160 mm.
Also, it is arranged such that the focal lengths of the projecting lenses
4, 5, 6 are 75 mm, the magnification is -15.5 times, the distances from
the image forming means to the corresponding projecting lenses are 79.8
mm, the distances from the projecting lenses to the screen are 1237.5 mm,
and the distances from the central projecting lens 5 to the peripheral
projecting lenses 4, 6 are 160 mm, respectively. According to this
arrangement, the angle formed between the optical axis Ax2 of the central
projecting lens 5 and the optical axes Ax1, Ax3 of the projecting lenses
4, 6 is 7.4.degree..
FIG. 73 shows a distortion and spot diagram of the image when lattice
charts are projected to the screen by the projecting optical systems B, C.
Since the spot diagram appears symmetrically with reference to y-axis,
only one side is shown in the Figure.
A lattice indicated by broken lines in the Figure is a image projected by
the system C, while the lattice indicated by a solid line is an image
projected by the system B. Since the projecting optical system C has such
distortion, a point expressed by the coordinate (y, z)=(30.5, 22.9) on the
LCD 12 is imaged at a point of (y, z)=(-454.0, -337.7) on the screen,
while a point expressed by the coordinate (y, z)=(-30.5, 22.9) on the LCD
12 is imaged at a point (y, z)=(501.1, -372.7) on the screen. If there
were no distortion of the image, the point of the LCDs should be imaged at
points (y, z)=(.+-.472.4, -354.3) on the screen.
The dots in the Figure show dispersion of luminous flux on each point. If
the image plane coincides with the screen, that is, if there is no focus
error at any points, luminous flux is focused into one point. The size of
the dot corresponds to the focus error of the image at the relevant
points. FIG. 73 shows the dispersion of the luminous flux enlarged by 20
times.
A projection image projected by the other peripheral projecting optical
system A generates a focus error and a line distortion symmetric with the
image formed by the projecting optical system C reference to the z-axis.
In order to reduce the focus error of an image, there has also been
proposed a projector shown in the type of FIG. 74.
The luminous flux having the components R, G and B and coming from the
charts 1, 2 are 3 are overlapped by a dichroic prism 8 and projected to
the screen 7 by the projecting lens 9. In order to overlap the luminous
flux, a dichroic mirror is also used besides the dichroic prism 8.
According to this method, since the luminous flux from each chart is
projected onto the screen 7 by a single projecting lens, no focus error
and distortion are generated.
However, in the construction shown in FIG. 74, the parallel luminous flux
is made incident to the dichroic prism, and the prism is required to be
the same size as the chart. If, therefore, the size of the chart is made
large in order to improve the resolution of the image the prism and the
projecting lens must also be large and high cost results.
The same problem is present when a dichroic mirror is used.
SUMMARY OF THE INVENTION
This invention has been developed to solve the above-mentioned problems. It
is therefore a general object of the invention to provide a projector
which is capable of preventing the focus error of each image on the screen
and avoiding the cost increase of the apparatus by not requiring the
diameter of the projecting lens to be made large.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view of a projector of Embodiment 1 according to the
present invention,
FIG. 2 is an enlarged view showing one of the peripheral projecting optical
systems in FIG. 1,
FIG. 3 is a schematic view showing the distortion of a projection pattern
formed by the optical system of FIG. 2,
FIG. 4 is a schematic view of a projector of Embodiment 2 according to the
present invention,
FIG. 5 is an enlarged view showing one of the peripheral projecting optical
systems in FIG. 4,
FIG. 6 is a schematic view of a projector of Embodiment 3 according to the
present invention,
FIG. 7 is an enlarged view showing one of the peripheral projecting optical
systems in FIG. 6,
FIG. 8 is a schematic view showing the distortion of a projection pattern
formed by the optical system of FIG. 7,
FIG. 9 is a schematic view of a projector of Embodiment 4 according to the
present invention,
FIG. 10 is an enlarged view showing one of the peripheral projecting
optical systems in FIG. 9,
FIG. 11 is a schematic view showing the distortion of a projection pattern
formed by the optical system of FIG. 10,
FIG. 12 is a schematic view of a projector of Embodiment 5 according to the
present invention,
FIG. 13 is an enlarged view showing one of the peripheral projecting
optical systems in FIG. 12,
FIG. 14 is a schematic view of a projector of Embodiment 6 according to the
present invention,
FIG. 15 is an enlarged view showing one of the peripheral projecting
optical systems in FIG. 14,
FIG. 16 is a schematic view of a projector of Embodiment 7 according to the
present invention,
FIG. 17 is an enlarged view of the light path overlapping portion in FIG.
16,
FIG. 18 is a schematic view showing the position of the luminous flux
transmitted by the projecting lens in FIG. 16,
FIG. 19 is a schematic view showing another embodiment of the position of
luminous flux transmitted by the projecting lens,
FIG. 20 is a schematic view of a projector of Embodiment 8 according to the
present invention,
FIG. 21 is an enlarged view of the light path overlapping portion in FIG.
20,
FIG. 22 is a schematic view of a projector of Embodiment 9 according to the
present invention,
FIG. 23 is an enlarged view of the light path overlapping portion in FIG.
22,
FIG. 24 is a schematic view showing the position of luminous flux
transmitted the projecting lens in FIG. 22,
FIG. 25 is a schematic view of a projector of Embodiment 10 according to
the present invention,
FIG. 26 is an enlarged view of the light path overlapping portion in FIG.
24,
FIG. 27 is a schematic view of a projector of Embodiment 11 according to
the present invention,
FIG. 28 is an enlarged view of the light path overlapping portion in FIG.
27,
FIG. 29 is a schematic view of a projector of embodiment 12 according to
the present invention,
FIG. 30 is an enlarged view of the light path overlapping portion in FIG.
29,
FIG. 31 is a schematic view of a projector of Embodiment 13 according to
the present invention,
FIG. 32 is an enlarged view of the light path overlapping portion in FIG.
31,
FIG. 33 is a schematic view of a projector of Embodiment 14 according to
the present invention,
FIG. 34 is an enlarged view of the light path overlapping portion in FIG.
33,
FIG. 35 is a schematic view of a projector of Embodiment 15 according to
the present invention,
FIG. 36 is an enlarged view of the light path overlapping portion in FIG.
35,
FIG. 37 is a schematic view of a projector of Embodiment 16 according to
the present invention,
FIG. 38 is an enlarged view of the light path overlapping portion in FIG.
37,
FIG. 39 is a schematic view of a projector of Embodiment 17 according to
the present invention,
FIG. 40 is an enlarged view of the light path overlapping portion in FIG.
39,
FIG. 41 is a schematic view of a projector of Embodiment 18 according to
the present invention,
FIG. 42 is an enlarged view of the light path overlapping portion in FIG.
41,
FIG. 43 is a schematic view of a projector of Embodiment 19 according to
the present invention,
FIG. 44 is an enlarged view of the light path overlapping portion in FIG.
43,
FIG. 45 is a schematic view of a projector of Embodiment 20 according to
the present invention,
FIG. 46 is an enlarged view of the light path overlapping portion in FIG.
45,
FIG. 47 is a schematic view of a projector of Embodiment 21 according to
the present invention,
FIG. 48 is an enlarged view of the light path overlapping portion in FIG.
47,
FIG. 49 is a schematic view of a projector of Embodiment 22 according to
the present invention,
FIG. 50 is an enlarged view of the light path overlapping portion in FIG.
49,
FIG. 51 is a schematic view of a projector of Embodiment 23 according to
the present invention,
FIG. 52 is an enlarged view of the light path overlapping portion in FIG.
51,
FIG. 53 is a schematic view of a projector of Embodiment 24 according to
the present invention,
FIG. 54 is an enlarged view of the light path overlapping portion in FIG.
53,
FIG. 55 is a schematic view of a projector of Embodiment 25 according to
the present invention,
FIG. 56 is an enlarged view of the light path overlapping portion in FIG.
55,
FIG. 57 is a schematic view of a projector of Embodiment 26 according to
the present invention,
FIG. 58 is an enlarged view of the light path overlapping portion in FIG.
57,
FIG. 59 is a schematic view of a projector of Embodiment 27 according to
the present invention,
FIG. 60 is an enlarged view of the light path overlapping portion in FIG.
59,
FIG. 61 is a schematic view of a projector of Embodiment 28 according to
the present invention,
FIG. 62 is an enlarged view of the light path overlapping portion in FIG.
61,
FIG. 63 is a schematic view of a projector of Embodiment 29 according to
the present invention,
FIG. 64 is an enlarged view of the light path overlapping portion in FIG.
63,
FIG. 65 is a schematic view of a projector of Embodiment 30 according to
the present invention,
FIG. 66 is an enlarged view of the light path overlapping portion in FIG.
65,
FIG. 67 is a schematic view of a projector of Embodiment 31 according to
the present invention,
FIG. 68 is an enlarged view of the light path overlapping portion in FIG.
67,
FIG. 69 is a schematic view of a projector of Embodiment 32 according to
the present invention,
FIG. 70 is an enlarged view of the light path overlapping portion in FIG.
69,
FIG. 71 is a view showing an optical system of a conventional projector,
FIG. 72 is an enlarged view of the light path overlapping portion in FIG.
71,
FIG. 73 is a schematic view showing the distortion of a projection pattern
formed by the optical system of FIG. 71, and
FIG. 74 is a schematic view of another type of a conventional projector.
DETAILED DESCRIPTION OF THE EMBODIMENTS
The present invention will now be described with reference to the
accompanying drawings.
Embodiment 1
FIGS. 1 to 3 shows the projector of Embodiment 1.
The projector, as shown in FIG. 1, is a color projector having three
projecting optical systems A, B and C and comprises three LCDs 10, 11 and
12 providing charts for forming images corresponding to colors RGB, and
three projecting lenses 30, 31 and 32 disposed corresponding to the LCDs
and adapted to project images onto a screen 20.
Disposed behind the LCDs are light sources (not shown) for the colors RGB.
By luminous flux corresponding to the colors transmitted through the LCDs,
images are formed onto the screen in an overlapping fashion through the
corresponding projecting lenses.
In the description of the embodiment, one must keep in mind that the
projecting lenses are ideal lenses in which the distance between two
principal points is 0 and which have no aberration, and the three lenses
mentioned are mutually compatible with one another. In FIG. 1, three
principal rays are shown for each LCD.
The optical axis Ax2 of the central projecting lens 31 is vertical or
perpendicular to the screen 20, while the optical axes Ax1, Ax3 of the
projecting lenses 30, 32 intersect with the optical axis Ax2 of the
projecting lens 31 at one point on the screen 20.
The LCD 11 of the central projecting optical system B is disposed so that
it is vertical or perpendicular to the optical axis Ax2 of the projecting
lens 31, while perpendicular lines of the LCDs 10, 12 of the peripheral
projecting optical systems A, C are tilted with respect to the optical
axes Ax1, Ax3 so that the image surfaces coincide with the screen 20 in
accordance with the Scheimpflug rule.
The screen 20 is of a known structure provided with a Fresnel lens on its
projecting lens side and with a lenticular pattern on its side that is
visible to the naked eye. The directions of rays of light coming from the
charts are orderly arranged with the Fresnel surface and the angle image
forming means of view field being adjusted by the lenticular pattern.
It is defined here, as in the case of the prior art description, that the
optical axis Ax1 is x-axis, the crossline between a plane including three
optical axes and the screen is the y-axis, and the direction perpendicular
to the y-axis on the screen is the z-axis.
Concrete numerical examples will now be described.
In the embodiments which will be described hereinafter, the image forming
means is an LCD of three inches size, the LCD of which a display area of
which is about 46 mm.times.61 mm, and a substrate of which is 160 mm in
the width direction.
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focal length of the projecting lenses
75 mm
magnification -15.5 times
distance from the chart to the lens
79.8 mm
distance from the lenses to the screen
1237.5 mm
distances between the central projecting
160 mm
lens 31 and the peripheral projecting
lenses 30, 32
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The perpendicular lines of the LCDs 10, 12 form an angle of 0.5.degree.
with the optical axes Ax1, Ax3 of the projecting lenses 30, 32, and the
angle formed between the optical axis Ax2 of the central projecting lens
31 and the optical axes Ax1, Ax3 of the peripheral projecting lenses 30,
32 is 7.4.degree..
FIG. 2 is a view showing one of the optical systems of FIG. 1, i.e., the
peripheral projecting optical system C in its enlarged scale together with
the luminous flux emitted thereby.
FIG. 3 is a view showing the distortion of an image which is formed when
lattice charts are projected onto the screen by the peripheral projecting
optical systems B, C.
One pattern, indicated by broken lines in the Figure, is a projected image
by the system B, while the other pattern, indicated by a solid line, is
the same image by the system C. Since the projecting optical system C has
the distortion, the coordinate (y, z)=(30.5, 22.9) on the LCD 12 is imaged
at a point of (y, z)=(-452.6, -336.6) on the screen, while the coordinate
(y, z)=(-30.5, 22.9) on the LCD 12 is imaged at a point (y, z)=(502.8,
-374.0) on the screen. If the projecting optical system C has no
distortion, these points should be imaged at points (y, z)=(.+-.472.4,
-354.3)on the screen.
In the construction of this embodiment, since the image surface coincides
with the screen and the luminous flux from one point on the LCD 12 is
imaged at one point on the screen, the irregularity of the spots shown by
dots in FIG. 73 is not detected.
An image formed by the central projecting optical system B is projected
onto the screen as a regular image without focus error and distortion,
while an image formed by the other peripheral projecting optical system A
is projected onto the screen with a distortion symmetric with the image
formed by the peripheral projecting optical system C.
Embodiment 2
FIGS. 4 and 5 show Embodiment 2 of the projector according to the present
invention. Identical materials to those of Embodiment 1 are denoted by
identical reference numerals in the embodiments as will be described
hereinafter and duplicate description will be omitted.
In Embodiment 1, the projector has an inconvenience that a trapezoidal
distortion of an image cannot be eliminated, although the focus error can
successfully be eliminated. There thus shown a construction in Embodiment
2 wherein both the focus error and trapezoidal distortion can be reduced.
As is shown in FIG. 4, all of the optical axes Ax1, Ax2, Ax3 of the
projecting lenses 30, 31, 32 are perpendicular to the screen 20. Also,
each of the LCDs 10, 11, 12 is disposed so that it is perpendicular to the
optical axis of the corresponding projecting lens. In the central
projecting optical system B, the LCD 11 is symmetrically arranged with
reference to the optical axis Ax2, while in the peripheral projecting
optical systems A, C, the LCDs 10, 12 are disposed such that they are
shifted in the y-axis direction relative to the optical axes Ax1, Ax3 of
the corresponding projecting lenses.
The numerical examples of Embodiment 2 will be described.
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focal length of the projecting lenses
75 mm
magnification -15.5 times
distances between the central projecting
160 mm
lens 31 and the peripheral projecting
lenses 30, 32
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FIG. 5 is a view showing the peripheral projecting optical system C in its
enlarged state together with the luminous flux. The shift amount of the
LCD 12 relative to the optical axis Ax3 is 10.3 mm.
The coordinate expressed by (y, z)=(.+-.30.5, 22.9) on each LCDs 10, 12 are
imaged at points expressed by (y, z)=(.+-.472.4, -354.3) on the screen.
This coordinate is the same to the projecting point by the projecting
optical system B.
According to Embodiment 2, both the focus error and trapezoidal distortion
are obviated.
In the construction of Embodiment 2, since the luminous flux from the LCDs
10, 12 of the peripheral projecting optical systems A, C is made incident
to the projecting lenses 30, 32 at angles, the projecting lenses 30, 32 of
the peripheral projecting optical systems A, C are required to have larger
image circles than the projecting lens 31 of the central projecting
optical system B. Therefore, if the projecting lenses are not made all the
same, in other words, if a lens of a small image circle is used as the
projecting lens 31 and lenses of a large image circle are used as the
projecting lenses 30, 32, amount of cost of the lenses can be reduced.
Quality of the image is deteriorated first from the peripheral portion due
to decrease of light quantity. The expression "image circle" refers to a
circle which serves as a border line between a portion where the quantity
of an image is sufficiently clear for use in a projector and another
portion where the quality of an image is not clear enough to satisfy the
requirements for use in a projector.
Embodiment 3
FIGS. 6 to 8 show Embodiment 3 of the projector according to the present
invention.
In the methods of Embodiment 1 and Embodiment 2, when the width of the LCD,
in particular, becomes large, the distance between the adjacent displays
must be set large. Accordingly, the angle between a ray projected towards
the screen from the center of a peripheral chart (i.e., 10 or 12) and the
x-axis (Ax2) becomes large, and the distance between the projecting lenses
becomes large.
Accordingly, the angles of rays of light are different for the colors RGB
when the rays of light are projected from the screen due to difference of
the angle of incidence of the rays of light relative to the screen. This
means that color of the screen looks different depending on the direction
from which the screen is seen, for example, in one case the image looks
somewhat red when viewed from one direction, while it looks somewhat blue
when viewed from the other direction.
Also, in the method of Embodiment 2, the shift amount of the LCD of the
peripheral projecting optical system becomes large, and a projecting lens
having a large image circle becomes necessary.
In Embodiment 3 since the mirror is used, the difference of the angle of
incidence is reduced to be small even in case where the width of the LCD
is large.
This projector, as shown in FIG. 6, includes the central projecting optical
system B, which has a projecting lens 31 of which the optical axis is
perpendicular to the screen 20, and the peripheral projecting optical
systems A, C which are disposed at both sides in symmetrical relation with
the central projecting optical system B placed therebetween. The
projecting optical systems A, C have mirrors 40, 41 for deflecting the
optical path towards for the screen 20. If the mirrors 40, 41 are not
disposed, the optical axes Ax1, Ax2, Ax3 of the projecting lens 30, 31, 32
would intersect at a point near the projecting lens 31. Moreover, it is
acceptable that the optical axes do not intersect at one point but they
come close to one another.
The projector shown in FIG. 6 is appropriate to add the mirrors into the
construction of FIG. 71, the optical axis Ax2 and the optical axes Ax1,
Ax3 deflected by the mirrors are intersected at one point on the screen
20. Each LCD is perpendicular to each optical axis of the projecting lens.
The projector of FIG. 6 is equivalent to the construction of the prior art
shown in FIG. 71 with a mirror added. Deflected optical axes are
intersected at one point on the screen 20 and the LCDs thereof are
perpendicular to the respective optical axes.
The numerical example of Embodiment 3 will now be described.
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focal lengths of the projecting lenses
75 mm
magnification -15.5 times
distances from the image forming means
79.8 mm
to the lenses
distances from the mirrors to the lenses
25 mm
distances from the mirrors to the screen
1212.5 mm
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Where the optical axes Ax1, Ax3 of the projecting lenses 30, 32 are
extended from the screen 20 side disregarding the mirror, the lengths of
the perpendicular lines drawn from the center of the central projecting
lens 31 toward the extended optical axes are 80 mm. The angle formed
between the optical axis Ax2 of the central projecting lens 11 and the
optical axes Ax1, Ax3 of the deflected peripheral projecting lenses 10, 12
is 3.7.degree..
FIG. 7 is a view showing one of the optical systems of FIG. 6, i.e., the
peripheral projecting optical system C in its enlarged scale together with
a luminous flux. FIG. 8 is a view showing the distortion and spot
diaphragm of the image when the lattice charts are projected onto the
screen by the projecting optical system B, C.
One pattern, indicated by broken lines in the Figure, is a projected image
by the system B, while the other pattern, indicated by a solid line, is
the same by the system C. Since the projecting optical system C has the
distortion, the coordinate (y, z)=(30.5,22.9) on the LCD 12 is imaged at a
point of (y, z)=(-452.0,-345.8) on the screen, while the coordinate (y,
z)=(-30.5,22.9) on the LCD 12 is image at a point (y, z)=(485.4,-363.3) on
the screen. If the projecting optical system C has no distortion, these
points should be imaged at points (y, z)=(.+-.472.4,-354.3) on the screen.
The dots in the Figure show dispersion of luminous flux on each point. FIG.
8 shows the dispersion of the spots in an enlarged state by twenty times.
The prior art shown in FIG. 71 and Embodiment 6 are different only in
difference of angle of the optical axes of the respective projecting lens.
Comparison between FIG. 73 and FIG. 8 reveals the fact that reduction of
the difference in angle reduces both the distortion and focus error of the
image.
An image formed by the central projecting optical system B is projected on
to the screen as a regular image which has no focus error and no
distortion, while an image formed by the other peripheral projecting
optical system A is projected onto the screen with a distortion symmetric
with the image formed by the peripheral projecting optical system C.
According to the construction of Embodiment 3, the optical axes of the
projecting lenses directed toward the screen can be mutually approached
irrespective of the size of the LCD, and the difference in incident angle
of the luminous flux of the projecting optical systems is reduced small
relative to the screen. As a result, the color shift caused by the visual
recognizing direction of the screen is reduced. Moreover, the focus error
and trapezoidal distortion become small.
If the mirrors 40, 41 are pivotable, even when the screen is moved and the
relative position of the image is changed on the screen, the image formed
by the peripheral projecting optical systems can be made coincident with
the image formed by the central projecting optical system. The mirrors 40,
41 may be pivoted independently. If there is a synchronizing mechanism for
causing two mirrors to pivot by the same angle, easier adjustment can be
obtained.
Embodiment 4
FIGS. 9 to 11 show the projector of Embodiment 4.
This projector has three projecting optical systems A, B, C as in
Embodiment 3, and the mirrors 40, 41 are provided to the peripheral
projecting optical systems A, C.
The projector of FIG. 9 is equivalent to the construction of Embodiment 1
shown in FIG. 1 with mirrors. Deflected optical axes are intersected at
one point on the screen 20 and the LCDs thereof are image forming means to
the optical axis Ax2, while the LCDs 10, 12 are inclined relative to the
optical axes Ax1, Ax3.
The numerical example for Embodiment 4 will now be described.
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focal lengths of the projecting lenses
75 mm
magnification -15.5 times
distances from the image forming means
79.8 mm
to the lenses
distances from the mirrors to the lenses
25 mm
distances from the mirrors to the screen
1212.5 mm
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In the case where the optical axes Ax1, Ax3 of the peripheral lenses 30, 32
are extended from the screen 20 side disregarding the mirrors, the lengths
of the perpendicular lines drawn from the center of the central projecting
lens 31 toward the extended optical axes are 80 mm.
Also, the LCDs 10, 12 of the peripheral projecting optical systems A, C are
disposed so that perpendicular lines of the LCDs is inclined by
0.24.degree. relative to the optical axes Ax1, Ax3, and the angle formed
between the optical axis Ax2 of the central projecting lens 11 and the
optical axes Ax1, Ax3 of the peripheral projecting lenses 10, 12 becomes
3.7.degree..
The angle of the mirrors 40, 41 relative to the optical axis is
46.7.degree..
FIG. 10 is a view showing one of the optical systems of FIG. 9, i.e., the
peripheral projecting optical system C in its enlarged scale together with
a luminous flux.
FIG. 11 is a view showing the distortion of an image which is formed when
lattice charts are projected onto the screen by this peripheral projecting
optical system B, C.
One pattern, indicated by broken lines in the Figure, is a projected image
by the system B, while the other pattern, indicated by a solid line, is
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