Projection type image display device maintaining resolution of an image unaffected by parallax

An image display device is arranged to have a liquid crystal light valve, a liquid crystal display panel, a backlighting unit, and a rod lens array. The liquid crystal light valve serves to form an image from the light applied thereto. The liquid crystal display panel serves to form a light pattern to be written to the liquid crystal light valve. The backlighting unit serves to apply light to the panel. The rod lens array is located between the liquid crystal panel and the liquid crystal light valve so that each of the light acceptance angle .theta. (half angle) and the degree of parallelization .alpha. (half angle) of light are not less than tan.sup.-1 {P/(3.sup.1/2.multidot.L)} (P is a pitch and L is a distance between the incident end of light and the pixel of the matrix type liquid crystal display panel) and at least one of the light acceptance angle .theta. (half angle) and the degree of parallelization a of light is 20.degree. or less.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a projection type image display device, in 
particular, the projection type image display device which operates to 
magnify an image appearing on a liquid crystal display and project the 
magnified image onto the screen. 
2. Description of the Related Art 
FIG. 10 shows an optical arrangement of a projection type image display 
device according to a first related art of the invention. The projection 
type image display device is arranged to have a reflective type liquid 
crystal light valve provided with a photoconductive layer. As shown, this 
type display device includes a CRT 112 for displaying an original image, a 
reflective type light valve 103 for forming and holding an image for the 
displayed image, a lens 113 located between the CRT 112 and the light 
valve 103, a light source 104 for applying a ray, a polarizing beam 
splitter 106 for applying the light from the light source 104 and passing 
specific polarized components of the light (reflected light) from the 
light valve, a lens 105 located between the light source 104 and the 
polarizing beam splitter 106, a projecting lens 107 for receiving the 
light passed through the polarizing beam splitter 106 and magnifying the 
image formed of the light, and a screen 108 on which the projected image 
is formed. 
When the image is displayed on the projection type image display device, 
the image displayed on the CRT 112 is applied to the reflective type 
liquid crystal light valve 103 through the lens 113 and the light source 
applies light of the liquid crystal light valve 103. 
FIG. 11 is a section showing an arrangement of the reflective type liquid 
crystal light valve 103. As shown, the light valve 103 is composed of a 
pair of glass substrates 115a, 115b, transparent electrodes 116a, 116b, 
and a photoconductive layer 117. The transparent electrodes 116a and 116b 
are formed of transparent conductive films (ITO) on the glass substrates 
115a and 115b, respectively. Then, amorphous silicon hydride (a-Si:H) is 
formed on the transparent electrode 116a and is served as the 
photoconductive layer 117. The amorphous silicon hydride (a-Si:H) is 
formed as the photoconductive layer 117 on the transparent electrode 116a. 
The amorphous silicon hydride is formed of silane gas and hydrogen gas by 
means of a plasma CVD method. A multilayered film of TiO.sub.2 and 
SiO.sub.2 is formed on the photoconductive layer 117 by means of the 
sputtering method. On the multilayered film, the polyimide films are 
spin-coated as orientation films 119a and 119b. Then, the molecular 
orientating treatment is done on the orientation films 119a and 119b by 
means of the rubbing technique. The resulting glass substrates 115a and 
115b are pasted with a spacer 120 laid therebetween. 
Mixing nematic liquid crystal having a chiral material added thereto is 
injected and sealed between the glass substrates 115a and 115b. This 
serves as a liquid crystal layer 121. The resulting composition is a 
hybrid field-effect mode reflective type liquid crystal light valve 103. 
The light valve 103 uses as an operating mode a vertical ECB mode or a 
guest host (GH) mode. 
Between the transparent electrodes 116a and 116b included in the light 
valve 103 arranged as above, there is applied a voltage from an A.C. power 
source 122. When the image from the CRT 112 enters from the glass 
substrate 115a, the impedance of the photoconductive layer 117 changes 
depending on the quality of incident light. With this change, the voltage 
applied to the liquid crystal layer 121 is changed, thereby changing the 
orientation of the liquid crystal, so that the image corresponding to the 
image from the CRT 121 may be formed on the liquid crystal layer 121. 
The light from the light source 104 enters into the reflective type liquid 
crystal light valve 103 on which an image is formed through the lens 105 
and the polarizing beam splitter 106, the incident light is reflected on a 
dielectric mirror 118 composing the light valve 113. Since the reflected 
light is passed through the portion of the liquid crystal layer 102 whose 
orientation, the reflected light changes its polarizing direction through 
the electro-optical effect. Hence, the selected reflected portion is 
allowed to be passed through the polarizing beam splitter 106. 
This reflected light is magnified through the effect of the projective lens 
107. The image formed on the light valve 103 is projected onto the screen 
108. In turn, the description will be oriented to an optical arrangement 
of a projection type image display device according to the second related 
art of the invention with reference to FIG. 12. This second related art is 
analogous to the first related art. Hence, the corresponding components 
have the same reference numbers. As disclosed in Japanese Patent Lying 
Open No. Hei 4-181226 or Hei 4-204919, the second related art is arranged 
so that a light source 123 may apply light to a transmittance display 
panel 125 and the light L1 passed through the panel 125 may form an image 
on the reflective type liquid crystal light valve 108. 
The use of the transmittance type display panel makes it possible to reduce 
the image display device in size. Recently, a high-resolution 
transmittance type display panel is now developed. The transmittance type 
display panel 125 used in the second related art does not operate to be 
luminous but the transmittance of the display panel 125 is changed on the 
driving signal so that the display panel 125 may modulate the intensity of 
the light from the light source provided in another light source for 
displaying an image or character. In this related art, several displays 
having light-passivation ceramics have been proposed such as a liquid 
crystal display panel, an electrochromic display, or a PLZT. In 
particular, the liquid crystal display panel is widely used for a 
pocket-sized TV (Television), a wordprocessor, or a projector. It is 
substantially completed. 
FIG. 13 shows an active-matrix liquid crystal panel as an example of a 
transmittance display panel 125. The liquid crystal panel is composed of a 
pair of opposite substrates 128a and 128b, a spacer 128 for keeping an 
interval between these opposite substrates, a liquid crystal layer 127 
sealed between the opposite substrates 126a and 126b, a switching element 
129, a pixel area 130, both of which are formed on the opposite substrate 
(TFT substrate) 126b, and a light cut-off layer 110 formed on the opposite 
substrate 126a and having an opening for the pixel area. 
In the foregoing arrangements, when an image displayed on the transmittance 
display panel is written in the photoconductive layer 117 of the 
reflective type liquid crystal light valve 103, the thickness of the glass 
substrate brings about a parallax, thereby making the image vague and 
lowering resolution. To cope with these shortcomings, it is necessary to 
form the overall display screen onto the photoconductive layer through the 
effect of just one lens. However, this arrangement makes the writing 
optical system larger in size. 
To keep the image clear, the overall image of the transmittance display 
panel is focussed on the photoconductive layer through the effect of one 
lens. This method enlarges the writing optical system. 
Further, the Japanese Patent Lying Open No. Hei 2-149823 discloses a 
technique in which fiber plates are used in place of the glass substrates 
for making the optical system compact. However, the fiber plate is so 
expensive that the overall image display device may be very costly. 
To solve the above shortcomings, the Japanese Patent Lying Open No. Hei 
2-55386 has disclosed a technique of providing means for forming an 
erected image with the same magnification, for example, a rod lens array 
between the CRT and the reflective type liquid crystal light valve. With 
this forming means, the image of the CRT is formed on the photoconductive 
layer. The thickness of the glass substrate does not bring about a 
parallax and the optical system is made compact. 
This technique, however, does not disclose a concrete acceptance angle of a 
rod lens array, a size of the image display means, a pitch of display 
pixels, or degree of parallel light. Further, at the filing time (August, 
1988) of the patent, no liquid crystal panel which has a higher resolution 
and is smaller than the CRT had been developed. Hence, the technique 
provides no concept of using a liquid crystal panel in place of the CRT. 
The U.S. Pat. No. 5,083,854 discloses a technique of locating a rod lens 
array between the liquid crystal panel and the reflective type liquid 
crystal light valve, magnifying a pixel opening of the liquid crystal 
display panel, and forming the magnified pixel portion onto the 
photoconductive layer. Moreover, the Japanese Lying Open No. Hei 2-149823 
discloses a technique of locating the fiber plate on the glass substrate 
located on the writing light source side of the reflective type liquid 
crystal light valve. 
However, the prior art disclosed in the Japanese Patent Lying Open No. Hei 
2-55386 uses the CRT. The reduced CRT offers a lower resolution because of 
the smaller diameter of an electron beam forming the image and the 
bleeding of a fluorescent material. Hence, the critical size of the CRT 
suitable to the HDTB is 5 inches. It means that the reduction of the 
optical system is limited. Further, since the CRT is effected by the 
geomagnetism, the image may be distorted or a conversion shift may take 
place in the three plate type projection using the reflective type liquid 
crystal light valve for each of the RGB colors. 
The prior art disclosed in the U.S. Pat. No. 5,083,854 is required to 
correspond the rod lens array to the liquid crystal display panel in 
one-to-one manner on the principle of the operation. Both of the pitches 
have to coincide with each other. In recent days, however, the liquid 
crystal panel is developed to have a pixel pitch of 100 .mu.m or less. The 
high-definition liquid crystal panel corresponding to the HDTV is recently 
developed to have a pitch of 30 .mu.m or less (SID '93 digest pp. 888 to 
886), while the now commercially available rod lens array is manufactured 
to have a pitch of 1 mm or less (Selfoc Lens produced by Japan Sheet Glass 
Company, Limited, for example). It is quite difficult to technically make 
both of them coincide with each other. If this difficult is overcome, one 
rod lens serves to prevent double image Formation of pixels adjacent to 
each other and thereby restrict the degree of parallel light. Hence, the 
writing light is made quite dark. If the pixel is shifted out of the rod 
lens, a moire pattern may take place. Hence, both of them are required to 
be accurately positioned. The positioning is quite troublesome. 
The technique of locating the fiber plate on the glass substrate on the 
writing light source of the reflective type liquid crystal light valve, as 
disclosed in the Japanese Patent Lying Open No. Hei 2-149828, enhances the 
cost of the image display device because the fiber plate itself is quite 
costly. 
SUMMARY OF THE INVENTION 
It is a first object of the present invention to provide an image display 
device which is arranged to output an image having a lower resolution 
resulting from a parallax if the glass substrate is used. 
It is a second object of the present invention to provide an image display 
device which provides a compact optical system and outputs a high 
resolution image. 
In carrying out the first object, according to a first aspect of the 
present invention, a projection type image display device includes: an 
optically writing type liquid crystal light valve; a matrix type liquid 
crystal display panel for forming a light pattern to be rewritten to the 
liquid crystal light valve; and means for forming an erected image with 
the same magnification, the means being located between the matrix type 
liquid crystal display panel and the liquid crystal light valve. 
The means for forming an erected image with the same magnification operates 
to form each pixel area on the photoconductive layer of the light valve. 
This makes it possible to realize an image whose resolution is not lowered 
by the parallax. 
As a preferable example of the means for forming an erected image with the 
same magnification, a refractive factor distribution type rod lens array 
may be referred as shown in FIG. 4. 
The refractive factor distribution type rod lens, as shown in FIG. 5, is a 
rod-like lens whose refractive factor is diminished from the center axis 
to the peripheral portion. The conventional lens operates to refract light 
on a curved I/O end surface and form an image from the refracted light, 
while the refractive factor distribution type rod lens operates to 
continuously refract the light according to the refractive factor 
distribution formed inside of the rod and to form the image from the 
refracted light. Hence, if both of the ends are planar, the rod lens 
serves as a lens effect. 
The refractive factor distribution type rod lens makes it possible to 
restrict the acceptance angle. If the backlighting unit is used for the 
light source, no lower contrast is brought about on the vision 
characteristic of the matrix type liquid crystal display panel for forming 
an image to be written. 
Though the image-forming range covered by each refractive factor 
distribution type rod lens is narrow, by locating the refractive factor 
distribution type rod lenses like an array matrix and slightly overlapping 
the adjacent rod lenses with each other, the overall screen is allowed to 
be completely covered by the rod lenses. It is therefore unnecessary to 
align the refractive factor distribution type rod lenses to the liquid 
crystal display panel. 
In carrying out the second object, according to a second aspect of the 
invention, a projection type image display device includes: an optical 
writing type liquid crystal light valve for forming an image from light 
applied thereto; a matrix type liquid crystal display panel for forming a 
light pattern to be written to the light valve; lighting means for 
applying light to the matrix type liquid crystal display panel; means for 
forming an erected image with the same magnification, for receiving light 
output from the matrix type liquid crystal display panel, the means being 
located between the matrix type liquid crystal panel and the liquid 
crystal light valve; and the means for forming an erected image with the 
same magnification having each of a light acceptance angle .theta. (half 
angle) and a degree of parallelization .alpha. (half angle) of the light 
output from the lighting means being not less than 
EQU tan.sup.-1 {P/(3.sup.1/2 .multidot.L)} 
and at least one of the light acceptance angle .theta. (half angle) and the 
degree of parallelization .alpha. (half angle) being not greater than 
20.degree., wherein P is a pitch of the means for forming an erected image 
with the same magnification and L denotes a distance between the 
light-incident end of the means for forming an erected image with the same 
magnification and the pixel of the matrix type liquid crystal display 
panel. 
According to a third aspect of the invention, a projection type image 
display device is characterized in that the matrix type liquid crystal 
display panel has a diagonal length of 76 mm (three inches size) or less. 
According to a fourth aspect of the invention, a projection type image 
display device is characterized in that the pitch of the pixels composing 
the matrix type liquid crystal display panel is 100 .mu.m or less. 
According to a fifth aspect of the invention, a projection type image 
display device is characterized in that the main light from the lighting 
means is applied to a vertical of the matrix type liquid crystal display 
panel in a manner to be inclined toward the viewing angle of the matrix 
type liquid crystal display panel. 
In operation, the projection type image display device according to the 
second aspect of the invention keeps the light acceptance angle .theta. 
(half angle) and a degree of parallelization .alpha. (half angle) of the 
light output from the lighting means not less than 
EQU tan.sup.-1 {(P/(3.sup.1/2 .multidot.L)} 
in which P denotes a pitch of the means for forming an erected image with 
the same magnification, L denotes a distance between the light-incident 
end and the pixel of the matrix type liquid crystal display panel means) 
and at least one of the acceptance angle .theta. (half angle) and the 
degree of parallelization .alpha. (half angle) equal to or lower than 
20.degree.. Hence, the image display device keeps the resolution proper 
against the parallax and outputs a high-contrast image. 
The projection type image display device according to the third aspect of 
the invention has a diagonal length of 76 mm (three inches size) or less 
in the matrix type liquid crystal display panel. Hence, the optical system 
of the display device is made compact. 
The projection type image display device according to the fourth aspect of 
the invention provides a pixel pitch of 100 .mu.m or less in the matrix 
type liquid crystal display panel. Hence, the optical system of the image 
display is made more compact. 
The projection type image display device according to the fifth aspect of 
the invention operates to apply the main light of the light output from 
the fiber light source through the collimate lens to a vertical of the 
matrix type liquid crystal display panel means, as being inclined to the 
vision direction of the matrix type liquid crystal display panel means. 
Hence, the light is applied to the most approximate vision direction of 
the liquid crystal display panel in order to obtain an image with a higher 
contrast. 
Further objects and advantages of the present invention will be apparent 
from the following description of the preferred embodiments of the 
invention as illustrated in the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In turn, the description will be oriented to a projection type image 
display device arranged to use a Selfoc Lens manufactured by the Japan 
Sheet Glass Company, Limited, according to a first embodiment of the 
invention. 
FIG. 1 is a model view showing the projection type image display device 
according to this embodiment. As shown in FIG. 1, a numeral 1 denotes an 
active-matrix liquid crystal display panel, in which a pixel pitch 
consists of 120.times.120 .mu.m in the horizontal and vertical and an 
opening consists of 60.times.60 .mu.m in the horizontal and vertical. The 
arrangement of the display panel is the same as that shown in FIG. 13. 
The liquid crystal display panel 1 operates to selectively transmit or cut 
off the writing light so that the writing light corresponding to the image 
to be displayed may be entered into a photoconductive layer 11 of a 
reflective type liquid crystal light valve 3. 
The light valve 3 has the same composition as that shown in FIG. 11. As 
shown, the liquid crystal display panel 1, the Selfoc Lens 2 and the light 
valve 3 are integrally composed with one another for forming a single 
liquid crystal shutter. 
To project the image displayed on the reflective type liquid crystal light 
valve 3 onto a screen 8, the light from a light source 4 is condensed 
through a condensing lens 5 and the condensed light is polarized into a 
linear beam through the effect of a polarizing beam splitter 6. The linear 
beam enters the reflective type liquid crystal light valve 3. The entered 
beam is reflected by a dielectric mirror 118, one of the components of the 
light valve 3 and again enters the polarizing beam splitter 6. If the beam 
impinging on the dielectric mirror 118 is passed through the 
image-displayed portion of the liquid crystal layer, that is, the portion 
of the liquid crystal to which an electric field is applied as result of 
the beam impinging onto the photoconductive layer 11, the passed beam 
changes its direction of polarization through the electro-optical effect 
of the liquid crystal. Hence, the passed beam is allowed to pass through 
the polarizing beam splitter 6. The passed light is projected on the 
screen 8 through the projecting lens 7. In addition, a numeral 9 denotes a 
backlighting unit for writing an image. 
FIG. 2 shows a fundamental composition of the Selfoc Lens. The Selfoc Lens 
2 has a diameter of 1.2 mm o and a distance of 720 .mu.m between an object 
and a lens or a lens and an image (which corresponds to 1.1 mm on the 
glass substrate having a refractive factor of 1.52) and serves to form an 
erected image with the same magnification. Plural rod lenses are arranged 
like an array. The glass substrate of the reflective type liquid crystal 
light valve 3 has a thickness of 1.1 mm. As a result, the image of the 
pixel opening is formed on the photoconductive layer through the effect of 
the Selfoc Lens 2 and the obtained image keeps the same resolution against 
the parallax. 
In this embodiment, as the refractive factor distribution type rod lens, 
the Selfoc Lens manufactured by the Japan Sheet Glass Company, Limited is 
used. In place, any lens may be used if it has a function of forming an 
erected image with the same magnification such as "SMILE lenses" 
manufactured by the Corning Inc. 
In turn, the description will be oriented to a projection type image 
display device according to a second embodiment of the present invention 
with reference to FIG. 3. 
The projection type image display device according to the second embodiment 
of the invention has the substantially same arrangement as that according 
to the first embodiment. Hence, the same components as those of the first 
embodiment have the same reference numbers. As shown, the display device 
is arranged to have a backlighting unit 9 serve as means for applying 
light. A liquid crystal display panel having a diagonal length of 76 mm 
(three inches size) 1 serves as the matrix type liquid crystal display 
panel for forming a light pattern. A rod lens array 12 serves to form a 
light pattern formed on the panel 1 as means for forming an erected image 
with the same magnification. A reflective type liquid crystal light valve 
3 forms an image for the light from the rod lens array 12. A reading light 
source 4 delivers light to a condensing lens 5 converts the light from the 
reading light source 4 into parallel rays. The parallel rays enter a 
polarizing beam splitter 6 which reflects the light in the predetermined 
polarizing direction. A projective lens 7 magnifies the reflected light 
passed through the splitter 6, and projects the magnified image onto a 
screen 8. The composition of the light valve 3 is the same as that shown 
in FIG. 13. Hence, it is not described. Like the first embodiment, the 
pixel pitch of the panel 1 consists of 40.times.40 .mu.m in the vertical 
and the horizontal and the opening consists of 20.times.20 .mu.m in the 
vertical and the horizontal. The liquid crystal display panel 1 uses an 
active-matrix system. 
The rod lens array 12, as shown in FIG. 4, includes plural rod lenses 12a 
laminated like a staggered matrix. The rod lens 12a is formed to diminish 
the refractive factor from the central axis to the peripheral portion. The 
conventional lens serves to refract the light on the curved end at which 
light is input or output for forming an image from the refracted light, 
while the rod lens, as shown in FIG. 5, serves to continuously refract the 
light on the refractive factor distribution formed inside of the rod lens 
for forming the image. Hence, if both of the ends are planar, the rod lens 
serves as a lens. As shown in FIG. 6a and FIG. 6b, the rod lens enables to 
restrict an acceptance angle .theta. by itself. As shown in FIG. 6a, if 
the acceptance angle .theta. is too small, the image-forming range for 
which each rod lens takes responsibility is so narrow that the 
image-forming ranges of the rod lenses are not overlapped with each other 
even if the rod lenses are located in an array manner. Thus, lots of voids 
appear on the image on the screen. 
To overcome this disadvantageous state, it is necessary to set the 
acceptance angle to be a following value or higher. The rod lens array 12 
is arranged so that the rod lenses are piled as shown in FIG. 7. To 
overlap the image-forming ranges of the rod lenses 12a with each other 
without any void on the image, assuming that a pitch of the rod lens 12a 
is P, a distance between the incident end of light and the pixel of the 
matrix type liquid crystal display panel is L, and the acceptance angle is 
.theta. (half angle), the image-forming range is required to be not less 
than the range covered by a dotted line of FIG. 7. For example, the radius 
of the image-forming range is required to be longer than the segment AB. 
Hence, it is necessary to set the acceptance angle .theta. to meet with 
the condition of: 
EQU tan.sup.-1 {P/(3.sup.1/2 .multidot.L)).ltoreq..theta. 
wherein A denotes a center of the rod lens 12a and B denotes a center of a 
regular triangle connecting three rod lenses. 
If, however, the acceptance angle is set to be too large, as shown in FIG. 
6b, the image contrast is made lower on the dependency of a view angle of 
the liquid crystal display panel. This invention, therefore, selects a 
minimum acceptance angle required to allow the image-forming ranges to be 
overlapped as a lower limit or such an acceptance angle as obtaining a 
higher contrast than a practical contrast, for example, 100 or more as an 
upper limit, for regulating the acceptance angle of the rod lens. 
Though the acceptance angle of the rod lens is restricted, the degree of 
parallelization of light applied to the liquid crystal display panel 1 is 
regulated as the acceptance angle of the rod lens. This regulation makes 
it possible to offer the same effect. 
The high-contrast optimal angle of view of the liquid crystal display panel 
depends on the rubbing direction. It is inclined by several angles against 
the vertical of the liquid crystal panel. Hence, it is more effective to 
restrict the acceptance angle and the degree of parallelization of light 
by inclining the light or the liquid crystal display panel in a manner to 
allow the light to enter into the display panel in the optimal direction 
of an angle of view. According to the present invention, it is not 
necessary to align the rod lens with the liquid crystal display panel. 
Next, the operation of the second embodiment will be described below. 
The light applied from the backlighting source 9 is selectively passed or 
cut off by the liquid crystal display panel 1. The passed light reaches 
the photoconductive layer 11 of the reflective type liquid crystal light 
valve 3 through the rod lens array 12. 
The light from the reading light source 4 is condensed by the condensing 
lens 5 and is polarized into a linear beam by the polarizing beam splitter 
6. Then, the linear beam is entered into the reflective type liquid 
crystal light valve 3. The light entered into the light valve 3 is 
reflected on the dielectric mirror 118 (see FIG. 11) and again enters into 
the polarizing beam splitter 8 (see FIG. 3). If the light reflected on the 
dielectric mirror 118 is passed through the portion of the liquid crystal 
layer on which the image is displayed or the portion of the liquid crystal 
to which an electric field is applied by entering the light to the 
photoconductive layer 11, the passed light changes the polarizing 
direction through the electro-optical effect of the liquid crystal so that 
the passed light may pass through the beam splitter 6. The passed light is 
magnified by the projecting lens 7 so that the image formed on the light 
valve 3 may be projected onto the screen 8. 
For example, the Selfoc Lens (trademark) manufactured by the Japan Sheet 
Glass Company, Limited is used as the rod lens array 12. In this 
embodiment, as shown in FIG. 2, each rod lens has a diameter of 1.2 mm o 
and a distance of 8 mm between an object and a lens or a lens and an image 
and serves to form an erected image with the same magnification. The rod 
lens are piled at a pitch of 1.3 mm like a two-dimensional array. The 
acceptance angle .theta. (half angle) is 
EQU tan.sup.-1 {1.3/(3.sup.1/2 
.multidot.8)}=5.3.degree..ltoreq..theta..ltoreq.20.degree. 
Hence, .theta.=10.degree. is established. 
Under the above condition, the image displayed on the liquid crystal 
display panel 1 is formed on the photoconductive layer 11 by the rod lens 
array 12. Hence, the image display device disables to lower the resolution 
in spite of the parallax and enables to offer an image of 100 or more 
contrast. 
The foregoing embodiment has been described by using the Selfoc Lens 
manufactured by the Japan Sheet Glass Company, Limited. Any lens may be 
used if it provides a function of forming an erected image with the same 
magnification such as "SMILE lenses" manufactured by the Corning Inc. 
Next, the description will be oriented to a projection type image display 
device according to a third embodiment of the present invention with 
reference to FIG. 9. The same components as those of the second embodiment 
shown in FIG. 3 have the same reference numbers and thus are not 
described. 
The projection type image display device provides a fiber light 14 served 
as a light source and a collimating lens 13 having a focal distance of 60 
mm. The fiber light has an outgoing end of 21 mm o. The collimating lens 
13 serves to regulate the degree of parallelization of the light. The rod 
lens has the same diameter, pitch, and distance between an object and a 
lens or a lens and an image as those of the second embodiment. By using 
25.degree. as the acceptance angle, the degree of parallelization .alpha. 
is allowed to be set by the following formula. 
##EQU1## 
Hence, like the first embodiment, it is possible to obtain a 
high-resolution and high-contrast image. 
Further, by shifting the outgoing end of the fiber light source 14 out of 
the optical axis, the light angle distribution is inclined toward the 
optimal angle of view of the liquid crystal display panel as shown in FIG. 
8 by about 4.degree. for obtaining a higher contrast of the resulting 
image. 
Many widely different embodiments of the present invention may be 
constructed without departing from the spirit and scope of the present 
invention. It should be understood that the present invention is not 
limited to the specific embodiments described in the specification, except 
as defined in the appended claims.