Observation apparatus comprising eyepiece optical systems

The present invention provides a head-mount image display apparatus which is maximumly reduced in size so as to arrange eyepiece optical systems in limited spaces such that the eyepiece optical systems do not touch the user's nose. The head-mount image display apparatus comprises LCD for displaying images for left and right eyes, eyepiece optical systems for guiding the images for left and right eyes displayed on the LCD to left and right eyeballs, body of the display apparatus for supporting the LCDs and the eyepiece optical systems for the left and right eyes such that the LCD and the eyepiece optical system for the right eyepiece is arranged at a predetermined distance from the LCD and the eyepiece optical system for the left eye, wherein corners of the eyepiece optical systems, at least which face a user's nose, are each provided with a chamfered portion planed off so as not to touch the user's nose.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a head-mount image display apparatus which a user 
wears on the head to see images. 
2. Description of the Related Art 
The head-mount image display apparatus used for watching images generally 
comprises a left image display element for displaying an image to be 
guided to a left eye, a left eyepiece optical system for guiding the left 
image to the left eye of the user, a right image display element for 
displaying an image to be guided to a right eye, and a right eyepiece 
optical system for guiding the right image to the right eye of the user. 
Various head-mount image display apparatuses are known, among which are: 
an apparatus having a pupil distance adjusting system and a diopter 
adjusting system (Jpn. Pat. Appln. KOKAI Publications 5-196898 and 
6-123852), an apparatus having a see-through system (Jpn. Pat. Appln. 
KOKAI Publication 5-268547), an apparatus for improving the image display 
(Jpn. Pat. Appln. KOKAI Publication 6-133253), and an apparatus reduced in 
size (Jpn. Pat. Appln. KOKAI Publication 6-334942). 
To decrease the size of a head-mount image display apparatus, the optical 
guide path for image viewing may be shortened. If the optical guide path 
is shortened, however, some of the image display elements are located near 
to the user's nose when the user wears the head-mount apparatus. Suppose 
either eyepiece optical system has at least three optical faces, e.g. a 
first face facing the eyeball and having a transmission effect, a second 
face having a reflection effect and having a rear reflecting mirror, and a 
third face facing an image display element and having the transmission 
effect. Then, one corner of the eyepiece optical system is so near to the 
user's nose as to touch the nose in some mounting conditions. As a result, 
the user feels uncomfortable while wearing the apparatus. 
With the conventional method, in order to solve this problem, the eyepiece 
optical system may be arranged such that the components of the apparatus 
do not touch the nose of the people whose pupil distance and positional 
relationship of eyes and nose fall within a predetermined range of normal 
distribution. If the eyepiece optical system is so designed, however, the 
head-mount image display apparatus cannot be maximumly reduced in size and 
thus cannot be compact. Therefore, the conventional apparatus wherein the 
eyepiece optical system has a part located too near the user's nose when 
the user wears the apparatus cannot have its size decreased and give the 
user a comfortable feeling. 
In the case where the eyepiece optical system comprises two prisms joined 
together, the prisms cannot easily be situated with desired precision 
(.+-.0.1 mm, for example) after the eyepiece optical system is assembled, 
unless the strict size management is achieved when the prisms are joined. 
In order to accomplish the size management of the prisms, it is necessary 
to provide to at least two planes as reference planes of the size 
management for each prism. However, when the eyepiece optical system 
comprises two prisms, reference plane of the size management is not 
provided to the prisms in the conventional head-mount image display 
apparatus. Therefore, the two joined prisms may shift along the joining 
face, and the eyepiece optical system cannot attain a predetermined 
precision. The image guided through such an eyepiece optical system may be 
deformed and difficult to see. 
SUMMARY OF THE INVENTION 
The object of the present invention is to provide a head-mount image 
display apparatus which is maximumly reduced in size so as to arrange 
eyepiece optical systems in limited spaces such that the eyepiece optical 
systems do not touch the user's nose. 
The head-mount image display apparatus of the present invention comprises 
image display elements for displaying images for left and right eyes; 
eyepiece optical systems for guiding the images for left and right eyes 
which are displayed on the image display elements, to left and right 
eyeballs; and positioning means for supporting the image display elements 
and the eyepiece optical systems for the left and right eyes such that the 
image display element and the eyepiece optical system for the right eye is 
set at a predetermined distance from the image display element and the 
eyepiece optical system for the left eye, wherein corners of the eyepiece 
optical systems, at least which face a user's nose, are each provided with 
a chamfered portion planed off in a predetermined manner so as not to 
touch the user's nose. 
Additional objects and advantages of the invention will be set forth in the 
description which follows, and in part will be obvious from the 
description, or may be learned by practice of the invention. The objects 
and advantages of the invention may be realized and obtained by means of 
the instrumentalities and combinations particularly pointed out in the 
appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
This invention can be more fully understood from the following detailed 
description of the head-mount image display apparatus according to a first 
embodiment of the present invention when taken in conjunction with the 
accompanying drawings. 
FIG. 1 shows that the image display apparatus comprising a display 
apparatus body 10 is attached to the head of a user. 
As shown in FIG. 1, the body 10 is connected to one end of side head frames 
11 each extending from the portion near the upper portion of each of the 
right and left ears of the user to the parietal portion of the user, and a 
parietal frame 12 extending on the parietal portion is connected between 
another end of the side head frames 11. 
The portions near the joint portions of the side head frames 11 and the 
body 10 are provided with metal plate springs 13 connected thereto at one 
end. Another end of the metal plate springs 13 is connected to left and 
right rear frames 14. 
Each of the left and right rear frames 14 are located in a portion 
positioned at the back of the ears and extending from the back of the head 
to the bottom of the neck of the user. The rear frames 14 are fixed 
together with the side frames 11 and the parietal frame 12 such that the 
body 10 is settled on the face of the user. The inner periphery of the 
parietal frame 12 is provided with a parietal pad 15 to be put on the 
parietal portion of the user. 
A headphone 16 is provided to portions of the body 10 near the ears of the 
user. There is also provided a cable 17 for transmitting an audio signal 
to the headphone 16 and transmitting a signal such as a video signal to 
the body 10. 
One end of the cable 17 is connected to a terminal (not shown) in the 
parietal frame 12 through the rear frame 14, plate spring 13, and the side 
head frame 11. The terminal, headphone 16, and body 10 are electrically 
connected by cables not shown. The other end of the cable 17 is connected 
to a video cassette reproduction apparatus 18 provided with sound 
controlling means 19 for controlling sound volume or the like. 
In the above-mentioned apparatus, a predetermined connecter may be provided 
to the end of the cable 17 on the side of the video cassette reproduction 
apparatus 18 such that the apparatus can be connected to the other known 
video cassette player. The cable 17 may be connected to a tuner for 
receiving the television broadcasting wave to receive the television 
broadcast or may be connected to an apparatus such as a personal computer 
so as to display computer graphic image, multimedia image, virtual reality 
image, and so on. The cable 17 may be replaced with a device such as an 
antenna to receive the images and audio signals from the outside which are 
carried by waves. 
FIG. 2 shows the structure of the optical system provided in the body 10. 
FIG. 2 is the drawing showing the eyepiece optical system 20 shown in FIG. 
3A, from an arrow A. The eyepiece optical system 20 is provided on the 
both sides of the left eyeball 21L and the right eyeball 21R of the user, 
to be arranged symmetrically and have the same structure. Accordingly, the 
description of the structure is provided only for the eyepiece optical 
system 20 on the side of the left eyeball 21L, and the description for the 
eyepiece optical system 20 on the side of the right eyeball 21R is 
omitted. 
As shown in FIG. 2, the eyepiece optical system 20 is located in front of 
the left eyeball 21L of the user. 
The eyepiece optical system 20 comprises first prism 22, second prism 23, 
and half mirror 24 inserted to the joining face of the first and second 
prisms 22 and 23 at the angle of 45.degree. with respect to the optical 
axis. The first prism 22, half mirror 24, and second prism 23 are joined 
together by a bonding method and the like. According to the bonding method 
employed here, the prisms and half mirror are bonded with a transparent 
sheet-like double-sided adhesive tape. 
The first prism 22 includes a first face 22a facing the left eyeball 21L 
and having a light-transmission effect, and a second face 22b having a 
reflection effect and having a rear reflection mirror. 
The second prism 23 has a third face 23a facing an image display element 25 
(more specifically, Liquid Crystal Display element, therefore, hereinafter 
referred to as LCD) and having a light-transmission effect. The LCD 25 is 
provided on the rear face with a backlight not shown. 
In the eyepiece optical system 20 having the above structure, the light 
beams of the image displayed in the LCD 25 is transmitted through the 
third face 23a at first, and then enter into the half mirror 24. The light 
beam transmitted through the half mirror 24 is reflected by the second 
face 22b, then enters into the half mirror 24 again. While, the light beam 
reflected by the half mirror 24 is transmitted through the first face 22a, 
then is guided to the user's eyeball. 
The head-mount image display apparatus according to this embodiment is 
provided with a pupil distance adjusting system 50 (shown in FIGS. 5A to 
5C) supporting the LCD 25 and eyepiece optical system 20 on the side of 
the left eyeball 21L and the LCD 25 and eyepiece optical system 20 on the 
side of the right eyeball 21R such that the LCD 25 and the eyepiece 
optical system 20 for the right eyeball 21R is arranged at a predetermined 
distance from that of the left eyeball 21L. 
As shown in FIG. 3A, the eyepiece optical system 20 is substantially formed 
in a rectangular parallelepiped. On at least one (shaded in FIGS. 3A and 
3B) of four corners of the eyepiece optical system 20, a chamfered portion 
26 is formed. The corner on which the chamfered portion 26 is formed faces 
the user's nose when the user wears the apparatus. The positional 
relationship of LCD 25 and the eyepiece optical system 20 when the user 
wears the apparatus is shown in FIG. 4. 
The chamfered portion 26 is preferable to be formed as small as possible so 
as not to decrease the image display area, more specifically, is 
preferable to be formed below the visual line E (shown in FIG. 2) of the 
user and in the region of one third of an entire area of the eyepiece 
optical system 20 from the bottom line. 
By providing the chamfered portion 26 in this manner, the eyepiece optical 
system 20 does not touch the user's nose even if the apparatus is reduced 
in size by shortening the optical guide path of the image observing 
optical system as shown in FIG. 4. Accordingly, even if the eyepiece 
optical system 20 may be arranged such that the components of the 
apparatus do not touch the nose of people whose pupil distance and 
positional relationship of eyes and nose fall within a predetermined range 
of normal distribution, the head-mount image display apparatus can be 
maximumly reduced in size and thus can be compact. 
In the above-mentioned example, as shown in FIG. 5A, the chamfered portion 
26 is provided only to the corner facing the user's nose. As shown in FIG. 
5B, the chamfered portion 26 may be provided to the lower two corners of 
the eyepiece optical system 20 so as to form the eyepiece optical system 
20 symmetrically in order to decrease the manufacturing cost. As shown in 
FIG. 5C, the chamfered portion 26 may be provided to all the corners of 
the eyepiece optical system 20 such that the eyepiece optical system 20 is 
formed to balance the upper portion with the lower portion of the eyepiece 
optical system 20 and the user does not feel discomfort. 
When the user observes the image, the backlight may shine through the 
periphery of the LCD and may enter the field of the user's vision to 
adversely affect the observing of the image. In order to solve this 
problem, it is preferable to provide between the LCD 25 and the eyepiece 
optical system 20 visual field limiting means (a visual field frame, for 
example) for limiting the visual field of the user. In this case, the 
corners of the visual field limiting means are preferable to be chamfered 
so as to correspond to the shapes of the eyepiece optical system 20 shown 
in FIGS. 5A to 5C, respectively. By providing the visual field limiting 
means in this manner, the image light beams can be prevented from being 
eclipsed. 
FIG. 6 shows a plan view of the eyepiece optical system 20 shown from the 
side of the second face 22b of the first prism 22. 
As shown in FIG. 6, the chamfered portion 26 is formed on each of the 
corners of the eyepiece optical portion 20. In order to prevent the image 
light beams from being eclipsed by the chamfered portions 26, the rear 
reflection mirror needs to be provided in the region enclosed by the 
broken line. When the rear reflection mirror is limited in the region 
enclosed by the broken line, the rear reflection mirror cannot be formed 
maximumly. 
In order to obtain the possibly large area of the rear reflection mirror, 
each of the corners of the second face 22b of the first prism 22 of this 
embodiment is provided with a chamfered portion 27 having the same shape 
(it is more preferable to round the corners) as that of the chamfered 
portion 26, and the entire face other than the chamfered portions 27 is 
coated with the rear reflection mirror. 
By forming the eyepiece optical system 20 in this manner, the effective 
area of the rear reflection mirror can be increased and the field angle of 
the prism can be increased when the size of the first prism 22 is 
determined in advance, in comparing with the case where the rear 
reflection mirror is formed in the region enclosed by the broken line. 
FIG. 7 shows the side view showing the eyepiece optical system 20 shown in 
FIG. 3A, from the arrow A. The second prism 23 of the eyepiece optical 
system 20 is provided with two planes 23b and 23c as the reference plains 
of the size management. 
By providing two planes 23b and 23c to the second prism 23 of the eyepiece 
optical system 20, the first and second prisms 22 and 23 can be joined 
together simultaneously with the measurement of the thickness D1 and 
height D2 of the eyepiece optical system 20, as mentioned later. As the 
result, the joining precision can be improved. 
The third face 23a facing the LCD 25 and having a light-transmission effect 
is formed so as to have a spherical central portion, and the face 23b is 
the tangential plain contacting the periphery of the third face 23a. The 
two planes 23b and 23c are provided to a portion through which the image 
light beam passing through the second prism 23 does not pass. Therefore, 
even if any damage of the plains such as a flaw is generated, the damage 
does not adversely affect the transmission of the image light beam. The 
use of the two planes 23b and 23c thus permits the size measurement with 
high precision. 
FIG. 8 shows the eyepiece optical system 20 contained in a joining jig 28. 
The joining jig 28 is formed such that the thickness D1 of the eyepiece 
optical system 20 is set at a desired value with an error of .+-.0.1 mm, 
for example, when the eyepiece optical system 20 is contained therein such 
that the inner periphery of the joining jig 28 contacts the first face 22a 
of the first prism 22 and the two planes 23b and 23c of the second prism 
23. 
The joining jig 28 is formed to have an open portion in a vertical 
direction with regard to the face of FIG. 8, and does not manage the size 
in a vertical direction with regard to the face of FIG. 8. Therefore, when 
the first and second prisms 22 and 23 are contained in the joining jig 28, 
it needs to be checked that ear portions 29-1 and 29-2 respectively 
provided to the ends of the first and second prisms 22 and 23 contact each 
other and do not form a step in a vertical direction with regard to the 
face of FIG. 8. By checking in this manner, the shift of the first and 
second prisms 22 and 23 in the vertical direction can be prevented. 
FIG. 9A shows the eyepiece optical system 20 contained in the joining jig 
30. FIG. 9B is the side view of the eyepiece optical system 20 shown in 
FIG. 9A without the joining jig 30. 
The joining jig 30 is formed such that the thickness D2 of the eyepiece 
optical system 20 is set at a desired value with an error of .+-.0.1 mm, 
for example, when the eyepiece optical system 20 is contained therein such 
that the inner periphery thereof contacts a maximum point P1 of the second 
face 22b of the first prism 22 and the two planes 23b and 23c of the 
second prism 23. 
The joining jig 30 is formed to have an open portion in a vertical 
direction with regard to the surface of FIG. 9, and does not manage the 
size in a vertical direction with regard to the face of FIG. 9. 
The process of assembling (joining) of the first and second prisms 22 and 
23 by use of the joining jigs 28 and 30 will be described below. 
At first, the first and second prisms 22 and 23 are contained in the 
joining jig 28, for example, then it is checked whether or not the 
thickness D1 is set at the desired value. 
Subsequently, the dimension between the plane 23c and the right end of the 
ear portion 29-2, between the right end of the ear portion 29-2 and the 
left end of the ear portion 29-1, and between the left end of the ear 
portion 29-1 and the first face 22a are measured respectively. 
After checking whether or not the measured distances are set at desired 
values, the joining is performed. 
The first and second prisms 22 and 23 are contained in the joining jig 30 
thereafter, and then it is checked whether or not the thickness D2 is set 
at the desired value. 
Subsequently, the dimension between the plane 23b and the upper end of the 
ear portion 29-2, between the upper end of the ear portion 29-2 and the 
lower end of the ear portion 29-1, and between the lower end of the ear 
portion 29-1 and the maximum point P1 of the second face 22b are measured 
respectively, and after checking whether or not the measured distances are 
set at desired values, the joining is performed. 
It goes without saying that the joining process is done over again when the 
measured dimensions are not set at desired values in the above process. 
In the assembling (joining) process as mentioned above, the planes 23b and 
23c shown in FIG. 9A are used as reference planes of the size management, 
and the upper, lower, left, and right ends of the ear portions 29-1 and 
29-2 shown in FIG. 9B are employed as reference planes of the size 
management. By using these planes to measure the thickness D1 and height 
D2 of the eyepiece optical system 20, D1 and D2 can be set at desired 
values (.+-.0.1 mm, for example). Especially, the distance between the 
second face (rear reflection mirror) 22b producing the main refraction 
power of the eyepiece optical system 20 and the LCD 25 can be precisely 
measured, resulting that the assembling (joining) process can be performed 
easily and the assembling precision can be improved. Accordingly, the 
image with high quality can be attained by use of the head-mount image 
display apparatus according to the present embodiment using the eyepiece 
optical system 20 satisfying the desired precision as mentioned above. 
FIGS. 10A and 10B respectively show the eyepiece optical system 20 provided 
with a joining plane 23d. 
The joining plane 23d is provided to the face of the second prism 23 on the 
side of the user's eyeball to be parallel with the plane 23c as the 
reference plane for the size management. 
When the first and second prisms 22 and 23 are joined each other by use of 
the joining plane 23d, a plane member 31 is provided to contact with the 
planes 23d and 22a, as shown in FIG. 10A. When the planes 23d and 22a are 
located on the same plain in this time, the planes 23d and 22a are 
parallel to each other and the prisms are joined as desired, and the 
joining step can be performed easily. 
In the above-mentioned first embodiment, the frames such as the mirror 
frame containing the components such as the eye optical system 20 and LCD 
25, and the visual field frame are used. It is more preferable to paint 
the frames in black or to perform reflection reducing coating on the 
frames for helping the observing the image. 
It is also preferable to employ the spring member (not shown) for fixing 
the eyepiece optical system 20 only by clipping therewith. 
The head-mount image display apparatus according to a second embodiment of 
the present invention will be described below in conjunction with FIGS. 11 
and 12. 
FIGS. 11 and 12 show the structure of an eyepiece optical system 40 
arranged in the body 10 (shown in FIG. 1) of the image display apparatus. 
FIG. 11 shows the eyepiece optical system 40 shown in FIG. 12 from an 
arrow D. The eyepiece optical system 40 is provided on the both sides of 
the left eyeball 21L and the right eyeball 21R of the user, to be arranged 
symmetrically and have the same structure. Accordingly, the description of 
the structure is provided only for the eyepiece optical system 40 on the 
side of the left eyeball 21L, and the description for the eyepiece optical 
system 40 on the side of the right eyeball 21R is omitted. 
As shown in FIG. 11, the eyepiece optical system 40 is located in front of 
the left eyeball 21L of the user. 
The eyepiece optical system 40 comprises a first face 40a facing the left 
eyeball 21L and having a light-transmission effect, a second face 40b 
having a reflection effect and comprising a rear reflection mirror, and a 
third face 40c facing the LCD 25 and having a light-transmission effect. 
The second face 40b is arranged to gradually extend the distance from the 
user's eyeball in a direction from the visual axis the E toward the image 
display element 25. The LCD 25 is provided with a backlight not shown on 
the rear face. 
In the eyepiece optical system 40 having the above structure, the light 
beams of the image displayed in the LCD 25 are transmitted the third face 
40c at first, and enter into the first face 40a. The light beam 
total-reflected by the first face 40a is reflected by the second face 40b, 
then enters into the first face 40a again. The light beam transmitted 
through the first face 40a is guided to the user's eyeball. The head-mount 
image display apparatus according to this embodiment is provided with a 
pupil distance adjusting system 52 (shown in FIGS. 13A and 13B) supporting 
the LCD 25 and eyepiece optical system 40 on the side of the left eyeball 
21L and the LCD 25 and eyepiece optical system 40 on the side of the right 
eyeball 21R such that the LCD 25 and the eyepiece optical system 40 for 
the left eyeball 21L is set at a predetermined distance from that of the 
right eyeball 21R. 
The eyepiece optical system 40 employed in the present embodiment can carry 
more light amount than that of the eyepiece optical system 20 employed in 
the first embodiment in which the light beam from the LCD 25 passes 
through half mirror 24 twice till the light beam reaches the eyeballs 21L 
and 21R of the user and the light amount is decreased thereby, and can be 
formed with a smaller thickness. 
As shown in FIG. 12, the eyepiece optical system 40 has a chamfered portion 
41 on at least one (shaded in FIGS. 11 and 12) of lower right and left 
corners of the eyepiece optical system 40. The corner on which the 
chamfered portion 41 is formed faces the user's nose when the user wears 
the apparatus. 
The chamfered portion 41 is preferable to be formed as small as possible so 
as not to decrease the area of the LCD 25. More specifically, the 
chamfered portion 41 is preferable to be formed below the visual axis E 
(shown in FIG. 12) of the user and in the region of one third of the 
entire area of the eyepiece optical system 40 from the bottom line. 
By providing the chamfered portion 41 in this manner, the eyepiece optical 
system 40 does not touch the user's nose even if the apparatus is reduced 
in size by shortening the optical guide path of the image observing 
optical system as shown in FIGS. 11 and 12. Accordingly, even if the 
eyepiece optical system 40 may be arranged such that the components of the 
apparatus do not touch the nose of people whose pupil distance and 
positional relationship of eyes and nose fall within a predetermined range 
of normal distribution, the head-mount image display apparatus can be 
maximumly reduced in size and thus can be compact. 
In the above-mentioned example, as shown in FIG. 13A, the chamfered portion 
41 is provided only to the corner facing the user's nose. As shown in FIG. 
13B, the chamfered portion 41 may be provided to the lower two corners of 
the eyepiece optical system 20 to form the eyepiece optical system 40 
symmetrically in order to decrease the manufacturing cost. 
When the user observes the image, the backlight may shine through the 
periphery of the LCD and may enter the field of the user's vision to 
adversely affect the observing of the image. In order to solve this 
problem, it is preferable to provide between the LCD 25 and the eyepiece 
optical system 40 visual field limiting means (a visual field frame, for 
example) for limiting the visual field of the user. In this case, the 
corners of the visual field limiting means are preferable to be chamfered 
so as to correspond to the shapes of the eyepiece optical system 40 shown 
in FIGS. 13A and 13B, respectively. By providing the visual field limiting 
means in this manner, the image light beams can be prevented from being 
eclipsed. 
In the above-mentioned second embodiment, the frames such as the mirror 
frame containing the components such as the eye optical system 40 and LCD 
25, and the visual field frame are used. It is more preferable to paint 
the frames in black or to perform reflection reducing coating on the 
frames for helping the observing the image. 
FIGS. 14A and 14B respectively show the other structure of the eyepiece 
optical system 40 of the head-mount image display apparatus according to 
the is second embodiment. The first face 40a of the eyepiece optical 
system 40 shown in FIGS. 11 and 2 is formed of one plane, while the first 
face 40a of the eyepiece optical system 40 shown in FIGS. 14A and 14B is 
provided with a draft portion 42 in which a wedge-shaped draft is formed. 
By forming the draft portion 42 in this manner, the eyepiece optical system 
40 can be easily cast off when the eyepiece optical system 40 is 
monolithically molded of plastic material, resulting in the improvement of 
the manufacturing efficiency. The eyepiece optical system 40 is 
monolithically molded of acrylic resin (PPMA, for example), so that the 
eyepiece optical system 40 is solid, and hard to be deformed. While, the 
eyepiece optical system 40 is monolithically molded of non-crystalline 
polyolefin, so that the eyepiece optical system 40 is formed so stable for 
humidity. 
The eyepiece optical system 40 also has a protruded portion 43 formed on at 
least one of left and right nooks of the third face 40c. With this 
structure, the eyepiece optical system 40 can be easily protruded from 
cast formed in a predetermined shape by contacting a pin not shown to the 
rear face of the protruding portion 43, i.e., the rear face of the 
eyepiece optical system 40 which is parallel to the first face 40a, to 
urge the face. In this time, the urging force of the pin is applied to the 
portion in the third face 40c of the eyepiece optical system 40 through 
which the image light beam is not transmitted (i.e., the nooks of the 
third face 40c), and thus the third face 40c is not deformed and the image 
is not also deformed. 
FIGS. 15A and 15B respectively show the still other structure of the 
eyepiece optical system 40 of the head-mount image display apparatus 
according to the second embodiment. 
As shown in FIGS. 15A and 15B, the eyepiece optical system 40 is provided 
with projected ear portions 44 on the left and right sides, respectively. 
The ear portions 44 are substantially formed in a square. Among the four 
faces of one ear portion, faces 44a and 44b are arranged so as to be in 
parallel to the first face 40a. 
The ear portions 44 are arranged on the left and right sides of the 
eyepiece optical system 40, through which the image light beam is not 
transmitted. The ear portions 44 are arranged on the faces through which 
the image light beam is transmitted, so that the faces on which the ear 
portions 44 are arranged is deformed thereby and the image is also 
deformed. 
With this structure, the eyepiece optical system 40 can be easily cast by 
contacting a pin 54 to the face 44b to urge the face 44b. The left and 
right ear portions 44 can be used to support or position the eyepiece 
optical system 40. 
Additional advantages and modifications will readily occur to those skilled 
in the art. Therefore, the invention in its broader aspects is not limited 
to the specific details, and representative devices shown and described 
herein. Accordingly, various modifications may be made without departing 
from the spirit or scope of the general inventive concept as defined by 
the appended claims and their equivalents.