JPH10206785A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ear-worn type display device which minimizes a range shielding a visual field or does not shield the visual field at all. SOLUTION: A display part consisting of a liquid crystal display device, an ocular, and a reflecting mirror is put in a housing 11, and a half-mirror 24 is provided on the housing 11. An ear hook part 12 is fitted to the housing 11 through a support part 13 and when this display device is put on, the housing 11 is positioned before the face so that only the half-mirror 24 is put in the visual field. The liquid crystal display device displays a laterally long image, whose video light is bent by the reflecting mirror in the longitudinal direction of the image and made incident on the ocular; and the lens transmitted light is bent by the half-mirror 24 again in the longitudinal direction of the image and guided to the eye. The half-mirror 24 transmits light from an outside field and a virtual image of the display image is observed while superposed on a background.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device used by being worn on a head, and more particularly, to a small display device used by being worn on an ear.

[0002]

2. Description of the Related Art A head mounted display (HMD) which is used by being mounted on a head and displays an image such as a moving image in front of an observer's eyes.
Is used in various fields including virtual reality. The HMD is formed in goggles or large spectacles so as to observe only a display image while blocking external light,
Usually, images are presented to both eyes. When the HMD is used, an image can be observed in any direction, but the outside world cannot be observed.

In recent years, there has been proposed a small-sized display device which displays an image in a part of a field of view and enables image observation while observing the outside world. This display device is not only for image observation, but mainly for assisting everyday life,
Unlike the conventional HMD, the displayed image is not a video of the object but information such as characters and numbers. Therefore, it is not necessary to give the image a three-dimensional effect, and the image is presented to only one of the left and right eyes.

For example, Japanese Patent Laid-Open Publication No. Hei 7-20960
No. 0 proposes a display device in which a liquid crystal display (LCD), a reflection mirror, an eyepiece, and the like are housed in one housing, and the housing is mounted on a frame of glasses or sunglasses. The housing is attached to the front upper part of one of the left and right lenses of the eyeglasses, and an image displayed on the LCD is given to one eye of the observer obliquely from above via a reflection mirror, an eyepiece, and a lens of the eyeglasses.

[0005]

However, in the display device of the above publication, the eyepiece and the reflection mirror for guiding the light from the LCD to the eyepiece are arranged in the field of view, so that the field of view of the observer is blocked by the reflection mirror. Will be done. If the field of vision is lacking, people will have difficulty in seeing and will also have difficulty observing the outside world. Actually, the housing that houses the eyepiece and the reflection mirror is also located in the field of view,
The range in which the field of view of the observer is obstructed is large, and the above-mentioned inconvenience becomes significant. In addition, since the display device is disposed only in front of one eye, the left and right visual field ranges are significantly unbalanced, thereby increasing annoyance and easily causing fatigue.

[0006] Further, since the display device is configured to be attached to eyeglasses or sunglasses, it cannot be used when a person who does not use eyeglasses or wears no sunglasses. Therefore, a person who does not use glasses in daily life needs to wear sunglasses or the like in order to use the display device, which is extremely inconvenient.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a display device that can be formed in a small size while minimizing the range of obstructing the visual field or not obstructing the visual field at all. It is an object of the present invention to provide a display device that can be used regardless of the above.

[0008]

In order to achieve the above object, the present invention has a display element and an eyepiece optical system, which is mounted on the observer's head and displayed on the display element by the eyepiece optical system. A display device that gives a virtual image of the image to the observer's eyes, in which a first optical path from the display element to the eyepiece optical system is bent.
And a second mirror that bends the optical path from the eyepiece optical system to the observer's eye.

Since the optical path from the eyepiece optical system to the observer's eye is bent by the second mirror, the eyepiece optical system is located at a position off the line of sight. Further, since the optical path from the display element to the eyepiece optical system is bent by the first mirror, the display element is arranged at a position off the optical axis of the eyepiece optical system. That is, even if the eyepiece optical system, the first mirror, and the display element are not present in the field of view, the observer can observe the image. In order to enable image observation via the eyepiece optical system, it is necessary to have an optical path length according to the focal length before and after the eyepiece optical system, but it is easy to secure it by bending the optical path become.

In the above display device, the second mirror is
The optical path from the eyepiece optical system may be bent and guided to the observer's eye, and a half mirror that transmits external light may be used. External light transmitted through the second mirror and reflected light from the eyepiece optical system enter the observer's eye, and a real image of the outside world and a virtual image of the display element are superimposed on each other, and the visual field is blocked by the display device. I can't.

Further, the display element displays an image whose length in the horizontal direction is twice or more the length in the vertical direction. The first mirror and the second mirror are arranged in parallel to the horizontal direction of the image. Deploy. The first and second mirrors arranged in parallel to the horizontal direction of the image bend the optical path in the vertical direction of the image, with the horizontal direction orthogonal to the optical path and the vertical direction oblique to the optical path. Since the displayed image has a length in the vertical direction that is equal to or less than half the length in the horizontal direction, the image is bent in a short vertical direction. Therefore, the width required for bending the optical path of the first and second mirrors may be short.

If the optical path is not bent in the horizontal direction of the image, the length direction of the display element substantially coincides with the left-right direction of the observer, and the length directions of the first and second mirrors are also the same. In the left-right direction. That is, a display element,
The first and second mirrors do not become long in the front-back direction or the up-down direction of the observer.

Preferably, a plurality of first mirrors are provided. When the optical path length from the display element to the eyepiece optical system is constant, the first
The greater the number of mirrors, that is, the greater the number of times the optical path is bent, the shorter the linear distance between the display element and the eyepiece optical system. The optical paths may intersect by bending a plurality of times, in which case the linear distance between the display element and the eyepiece optical system can be further reduced.

Specifically, the optical path from the display element to the eyepiece optical system is crossed at least twice. As the number of optical path crossings increases, the linear distance between the display element, the eyepiece optical system, and the first mirror can be reduced, and the space occupied by these elements can be reduced. As aforementioned,
The width of the first mirror required for bending the optical path is short, and it is not possible to arrange a plurality of first mirrors close to each other or to arrange the first mirror close to a display element or an eyepiece optical system. Because of its simplicity, it is possible to cross the optical path many times, thereby making the occupied space smaller.

The first mirror bends the optical path by 90 ° or more. The larger the bending angle, the closer the light path on the incident side and the light path on the reflection side, and the shorter the linear distance between the display element and the eyepiece optical system. Further, as the bending angle increases, the width of the mirror required for bending the optical path becomes shorter, and the first mirror can be made smaller.

The first mirror may have a curvature in the direction in which the optical path is bent. When the optical path is bent by the mirror, the vertical length of the image changes.
That is, the image is enlarged or reduced in the vertical direction, and the function of the eyepiece optical system is partially performed by the first mirror.

In order to achieve the above object, the present invention also provides a display device comprising: a display unit comprising an image display system and an observation optical system; and a half mirror attached to the display unit and guiding light from the display unit to an eye. , An ear-hook type including an ear-hook portion, a support portion for connecting the display portion and the ear-hook portion and positioning the half mirror near the eye. This display device is configured to be used by putting it on an ear, and a half mirror is positioned near the front of the eyes when used. The half mirror provides light to the observer without blocking light from the outside world and guides light from the display unit to the eye. Therefore, the image of the display unit is observed in the same field of view as the state where the display device is not used.

It is preferable to provide a position adjusting mechanism for adjusting the relative position between the ear hook and the display unit, and a direction adjusting mechanism for adjusting the direction of the half mirror. The position of the display unit and the position and orientation of the half mirror can be adjusted, and the position of the image in the field of view and the direction of the image with respect to the line of sight can be adjusted.

Only one set of the display unit and the half mirror may be provided for monocular viewing. It becomes a simple display device.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a display device according to the present invention will be described with reference to the drawings. FIG. 1 shows the appearance of a display device according to an embodiment of the present invention. The display device 1 displays information in characters and numerals and presents the display in front of the observer, and is configured to be used by the observer hanging on one ear. Hereinafter, this display device is referred to as an EMCD (Ea
r Mounted Character Display.

The EMCD 1 has a housing 11, an ear hook 12, and a support 13 for connecting the housing 11 to the ear hook 12. The housing 11 houses a display unit including a display element, an eyepiece optical system, and a reflection mirror, and has a half mirror 24 mounted thereon for guiding light of the display element to the eyes.

The ear hook portion 12 is formed in a shape along the rear part of the human earlobe, and is connected to the support portion 13 at the lower end. By hanging the ear hook 12 on the upper part of the earlobe from behind, the support 13 protrudes forward from under the earlobe, and the housing 11 is held at a position in front of the face below one eye. At this time, the half mirror 24 enters the visual field. By locating the support 13 below the earlobe, the EMCD 1 can be easily used even while wearing spectacles or the like.

A rotation mechanism 13a is provided at a connection portion between the support portion 13 and the ear hook portion 12, and the support portion 13 is rotatable in a vertical direction. By moving the support 13 up and down, the vertical position of the housing 11 can be adjusted.
The support portion 13 is formed by covering a metal bar with a resin, and can be bent freely. The vertical position of the housing 11 can be adjusted by bending the support portion 13, and the horizontal position and the front-back position of the housing 11 can also be adjusted.

A rotation mechanism 13b is provided at a joint between the housing 11 and the support portion 13, and the housing 11 is rotatable in a vertical direction. By rotating the housing 11,
The direction of the image to be observed can be adjusted by changing the vertical direction of the housing 11 and the half mirror 24 with respect to the eyes.

The two ends of the half mirror 24 are supported by the columns 14. The joint between the support 14 and the housing 11 and the joint between the support 14 and the half mirror 24 are screwed so as to be rotatable. When the EMCD 1 is not used, the half mirror 24 is folded and the housing 11 is folded.
Can be brought into close contact with the upper surface of the substrate. Further, the relative orientation of the housing 11 and the half mirror 24 can be changed, and the direction of the image to be observed can be adjusted by changing the angle of the half mirror 24 with respect to the housing 11. A window 11a is formed on the upper surface of the housing 11, and light from the display unit in the housing 11 reaches the half mirror 24 through the window 11a.

FIG. 2 shows a modified example of the appearance of the EMCD 1. The support part 13 is similar to ordinary glasses,
And is directed obliquely downward and forward from above the earlobe.

FIG. 3 schematically shows the optical configuration of the EMCD 1. The EMCD 1 includes an LCD 21 as a display element, a lens 22 forming an eyepiece optical system, and a reflection mirror 23 disposed on an optical path from the LCD 21 to the lens 22 to bend the optical path. These constitute a display unit and are housed in the housing 11. The light of the LCD 21 enters the observer's eye via the reflection lens 23, the eyepiece optical system 22, and the half mirror 24. The observer uses the half mirror 24 and the eyepiece optical system 2
Through 2, a virtual image of the image displayed on the LCD 21 is observed.

The LCD 21 displays character information using characters such as kanji, hiragana, katakana, alphabets, arithmetic numerals and symbols that can be treated as characters. The display surface of the LCD 21 is set so that the length in the horizontal direction is twice or more the length in the vertical direction, specifically, the size of 7 mm in length and 18.4 mm in width, and one to several lines in the horizontal direction. Is displayed. In order to reduce the size of the housing 11, the LCD 21
The drive section including the drive circuit and the battery for power supply is formed separately from the housing 11, and is configured to be attached to the ear hook section 12 (not shown).

As the lens 22, a diffractive optical element having a positive power is used. The diffractive optical element is manufactured, for example, by forming a diffraction grating on a transparent resin plate, and has a feature of being thin and lightweight. A Fresnel lens may be used instead of the diffractive optical element. Lens 22
Is f '= 31.5 mm, fNo. = 7.8 (pupil diameter φ = 4
mm), β = 0.0105, and L
The display surface of the CD 21 is observed as a virtual image located 70 m in length and 184 cm in width located 3 m in front.

FIG. 4 shows a cross section and set dimensions (unit: mm) of the optical system of the EMCD 1. Lens 22, reflection mirror 2
The half mirror 24 and the half mirror 24 are formed in a horizontally long rectangle corresponding to the display surface of the LCD 21, and are arranged such that long sides thereof are parallel to the horizontal direction of the display surface of the LCD 21. The lens 22 is disposed substantially horizontally, and its optical axis AX passes through the center of the reflection mirror 23. The reflection mirror 23 is inclined by 45 ° with respect to the optical axis AX.
Is bent at right angles by the reflection mirror 23 and the LCD 2
1 passes through the center of the display surface. The LCD 21 is arranged so that the vertical direction of the display surface is parallel to the optical axis AX of the lens 22, and therefore, the horizontal direction of the display surface is substantially horizontal.

In the above arrangement, the light from the LCD 21 is bent by the reflecting mirror 23 in the vertical direction of the image,
After passing through the lens 22, the image is again bent in the vertical direction of the image by the half mirror 24. Therefore, the optical path is not bent in the lateral direction of the image, that is, in the length direction.

The half mirror 24 is variable in angle as described above, but is normally used in a state of being inclined by 45 ° with respect to the optical axis AX. The half mirror 24 reflects the light from the LCD 21 transmitted through the lens 22 to guide the light to the observer's eyes, and transmits the light from the outside world without blocking.
Therefore, a virtual image of the image displayed on the LCD 21 is reflected on the observer's eyes so as to overlap the background. 5 and 6 show the positional relationship between the visual field and the virtual image. Virtual image M is field of view FV
Observed to the right or left at the bottom of the.

These figures show the image positions in a standard use state.
By changing the position and orientation of the first and half mirrors 24, the image position in the field of view can be adjusted.
In the illustrated standard position, only the half mirror 24 attached to the upper part of the housing 11 is in the field of view, and the housing 11 itself is out of the field of view. Therefore, the field of view of the observer is not blocked by the housing 11.

FIG. 7 shows an optical configuration of another embodiment of the present invention.
FIG. 8 schematically shows this. Also in these configurations, the LCD 21 has a horizontally long display surface, and the reflection mirror and the half mirror are arranged so that the optical path is bent in the vertical direction of the image and not in the horizontal direction.

In the configuration shown in FIG. 7A, the LCD 21 is moved closer to the lens 22 as compared with FIG.
The angle of the reflection mirror 23 with respect to the optical axis AX of the lens 22 is close to 90 °. The light path on the incident side and the light path on the reflection side of the reflection mirror 23 are close to each other, and the space occupied by the LCD 21, the lens 22, and the reflection mirror 23 is reduced as a whole.

In the configuration shown in FIGS. 7B to 7D, two reflection mirrors 23a and 23b are arranged,
The optical path from to the lens 22 is bent twice. In (c) and (d), the optical paths intersect once. (E)
And (f) have three reflecting mirrors 23a, 23b,
The optical path from the LCD 21 to the lens 22 is bent three times and crosses twice or three times.

As described above, as the number of reflecting mirrors is increased and the number of times of bending of the optical path is increased, the lens 21 is moved from the LCD 21 to the lens
2 and the space required for the optical configuration can be reduced. Further, as the number of crossings of the optical path increases, the LCD 21, the lens 22, and the reflection mirror can be arranged closer to each other, and each component can be arranged in a smaller space. The number of reflection mirrors may be increased to further increase the number of crossings of the optical path.

Since the reflecting mirrors 23a to 23c bend the optical path in the longitudinal direction of the image, that is, in the short direction, the width required for bending the optical path is much shorter than in the case of bending in the horizontal direction. Moreover, the reflection mirrors 23a to 23c
Are arranged so as to bend the optical path by 90 ° or more, and the optical axis on the incident side and the optical axis on the reflection side form a right angle or an acute angle. For this reason, the width of each reflection mirror is 1.4 times (square root 2) times or less the optical path width corresponding to the vertical direction of the image. Therefore, each of the reflection mirrors 23a to 23c is formed to be thin, and it is possible to shorten the center-to-center distance between the reflection mirrors 23a to 23c without making them touch the LCD 21 or the lens 22.

The configuration shown in FIG. 7 (g) includes two reflection mirrors 23d and 23e having curvatures in the optical path bending direction instead of the plane reflection mirrors 23a and 23b of FIG. 7 (c). The reflection mirrors 23d and 23e have no curvature in the direction perpendicular to the optical path bending direction, and reduce the image in the vertical direction without changing the length in the horizontal direction. Therefore,
The aspect ratio of the virtual image observed by the observer is smaller than the aspect ratio of the image displayed on the LCD 21.

Depending on the setting of the curvature of the reflection mirrors 23d and 23e, the reduction ratio can be adjusted, and conversely, the image can be enlarged in the vertical direction. A reflective mirror having a curvature not only in the direction of bending the optical path but also in the direction perpendicular thereto may be used to enlarge or reduce the image in the horizontal direction. As described above, when the reflecting mirror having the curvature is used, the function of the lens 22 as the eyepiece optical system is partially substituted by the reflecting mirror, and the characteristics required for the lens 22 can be reduced. Here, the same mirrors 23d and 23e are used to minimize the types of components.

FIG. 8 shows a configuration in which a reflecting prism is used together with a reflecting mirror to bend the optical path from the LCD 21 to the lens 22. The configuration (a) includes a prism 25 having a reflection surface 25a, a １ ／ λ wavelength plate 26, and a reflection mirror 23. The polarized light from the LCD 21 is transmitted through the prism 25 and the ４λ wavelength plate 26, is reflected by the reflection mirror 23, and is again 再度 λ.
The light passes through the wave plate 26 and enters the prism 25. Light is 1 /
The light passes through the 4λ wavelength plate 26 twice, is shifted by a half wavelength, is reflected by the reflection surface 25 a, and is guided to the lens 22.

The light travels back and forth between the reflection surface 25a and the reflection mirror 23, and the optical path is twice as long as the distance between the prism 25 and the reflection mirror 23. By using the reflecting prism in this way, it is possible to lengthen the optical path while keeping the space occupied by the entire optical configuration small.

The arrangements of (b) and (c)
One or two reflecting mirrors are added between the prism 25 and the prism 25. The configuration (d) uses a prism 27 having a reflective surface 27a having a curvature in the optical path bending direction instead of the prism 25 having the flat reflective surface 25a shown in (a). This reflective surface
Similar to the reflection mirrors 23d and 23e in FIG. 7G, the function partially substitutes for the function of the lens 22 as the eyepiece optical system.

As described above, the display device of the present invention can display a horizontally long image and bend the optical path in the vertical direction, thereby making it possible to reduce the size of the entire device. By arranging it in the field of view, it is possible to present an image without interrupting the field of view at all.

In place of the half mirror, the optical path from the eyepiece optical system to the eye can be bent by a total reflection mirror. In that case, a part of the field of view is obstructed, but the obstruction that obstructs the view is only the mirror, not the housing that houses the optical system, and the mirror has a small shape that is long and narrow horizontally. As compared with the conventional apparatus, the range in which the visual field is blocked is significantly reduced.

In the present invention, since the display device is of the ear-hung type, it can be worn regardless of whether or not glasses are worn, and anyone can use it anywhere. Moreover, since the position and angle of the display device with respect to the observer's eyes can be adjusted, anyone can easily observe a clear image, and in combination with the fact that the field of view is not obstructed, It is possible to reduce eye fatigue.

Although an example in which an LCD is used as a display element has been described here, characters and numerals may be displayed using light emitting diodes (LEDs) that perform segment display. -Anything can be used as long as it displays a light and horizontally long image. Also, a pair of a display element, an eyepiece optical system, and a set of optical elements for bending the optical path are provided, and not a device for monocular vision,
It may be a device for binocular use.

[0048]

According to the display device of the first aspect, the optical path length required for image observation while shortening the linear distance between the display element, the eyepiece optical system, and the observer's eye by bending the optical path. Can be secured. Therefore, the display device can be formed in a small size, which is suitable for a use mode in which the display device is mounted on the head. Further, it is possible to arrange the display element and the eyepiece optical system outside the field of view of the observer,
The range in which the visual field is blocked by the display device can be reduced.

In the display device according to the second aspect, since the second mirror is a half mirror and transmits external light, the field of view is not obstructed by the second mirror. Therefore,
The observer can observe the same visual field range as when the user does not wear the display device, and is free from the troublesomeness of missing a part of the visual field.

Since the display device according to the third aspect displays a horizontally long image, it is suitable for displaying not only Japanese but also foreign characters and arithmetic numerals which are usually written horizontally. In addition, since the vertical and horizontal relationship of the display image matches a human visual field that is wider in the left-right direction than in the vertical direction, image observation is easy. In addition, since the first and second mirrors bend the optical path not in the horizontal direction but in the short vertical direction of the image, the mirror width in the bending direction is reduced, and each mirror and the eyepiece optical system and the display element are arranged in close proximity. It is possible to Therefore, the display device can be formed small.

Further, it is also possible to adopt a configuration in which the optical path is not bent in the horizontal direction of the image. Can be. In this case, the lower limit of the length of the display device in the front-rear direction is not restricted by the lengths of the display element and the first and second mirrors, and the device can be formed thin. That is, the display device can be kept thin even when an image having a large ratio of the length in the horizontal direction to the vertical direction is displayed.

In the display device according to the fourth aspect, since the number of bending of the optical path is increased by providing a plurality of first mirrors, the display device is downsized while securing a necessary optical path length in front of the eyepiece optical system. Can be done easily.

In the display device according to the fifth aspect, the display element, the eyepiece optical system and the first mirror can be arranged close to each other by intersecting the optical path from the display element to the eyepiece optical system at least twice. The size of the display device can be reduced more easily. Further, the degree of freedom of the arrangement position of the display element increases, and the optical design becomes easy.

In the display device according to the sixth aspect, since the light path on the incident side and the light path on the reflection side are made closer by increasing the bending angle of the light path, the display element and the eyepiece optical system can be brought closer. Further, since the width of the mirror required for bending the optical path becomes shorter, the first mirror can be made smaller. With these effects, the size of the display device can be further reduced.

In the display device according to the seventh aspect, the first mirror performs a part of the function of the eyepiece optical system, and the eyepiece optical system can be simplified. Further, even when the same display element or eyepiece optical system is used, it is possible to change the aspect ratio of the observed virtual image depending on the curvature of the mirror.

According to the display device of the eighth aspect, since the image is presented by the half mirror, the visual field is not obstructed. In addition, since it is configured to be worn on the ear, it can be used with eyeglasses or alone, and anyone can use it. It is very easy to mount and hassle-free when attaching and detaching.

In the display device according to the ninth aspect, since the relative position between the ear hanging portion and the display portion can be adjusted, the observer can arbitrarily set the upper, lower, left, and right positions of the display portion as desired. In addition, the display device can be reliably positioned outside the field of view. Further, since the distance from the eye to the observation optical system can be made constant by adjusting the front and rear positions of the display unit, anyone can easily observe a clear image.

In the display device according to the tenth aspect, the direction of the image with respect to the eye can be adjusted by adjusting the direction of the half mirror. Therefore, regardless of the position of the display unit, it is possible to make the image substantially perpendicular to the line of sight when the observer points his or her line of sight to the image, and image observation is easy.

The display device for monocular vision according to the eleventh aspect can be formed in a small size, is convenient to use, and is easy to carry.

[Brief description of the drawings]

FIG. 1 is a view showing the appearance of a display device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a modified example of the appearance of a display device.

FIG. 3 is a diagram schematically showing an optical configuration of the display device.

FIG. 4 is a diagram showing a cross section and set dimensions of an optical system of the display device.

FIG. 5 is a diagram showing a vertical positional relationship between a visual field and a virtual image in the display device.

FIG. 6 is a diagram showing a position of a virtual image in a field of view of the display device.

FIG. 7 is a diagram schematically showing an optical configuration of another embodiment of the present invention.

FIG. 8 is a diagram schematically showing an optical configuration using a reflection prism according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 EMCD (ear-hanging type character display device) 11 Housing 12 Ear-hook part 13 Support part 21 LCD (display element) 22 Lens (eyepiece optical system) 23, 23a-23e Reflection mirror (first mirror) 24 Half mirror (first mirror) 2 mirror) 25, 27 reflective prism

Claims (11)

[Claims] 1. A display device comprising a display element and an eyepiece optical system, which is mounted on a head of an observer and gives a virtual image of an image displayed on the display element by the eyepiece optical system to an eye of the observer. A display device comprising: a first mirror that bends an optical path from the display element to the eyepiece optical system; and a second mirror that bends an optical path from the eyepiece optical system to an observer's eye. 2. The second mirror according to claim 1, wherein the second mirror is a half mirror that bends an optical path from the eyepiece optical system to guide the light to an observer's eye and transmits external light. Display device. 3. The display device displays an image whose horizontal length is twice or more the vertical length, and wherein the first mirror and the second mirror are parallel to the horizontal direction of the image. The display device according to claim 1, wherein the display device is disposed on a display device. 4. The display device according to claim 3, wherein a plurality of said first mirrors are provided. 5. The display device according to claim 4, wherein an optical path from the display element to the eyepiece optical system intersects at least twice. 6. The display device according to claim 3, wherein the first mirror bends an optical path by 90 ° or more. 7. The display device according to claim 3, wherein the first mirror has a curvature in a direction in which an optical path is bent. 8. A display unit comprising an image display system and an observation optical system, a half mirror attached to the display unit and guiding light from the display unit to the eye, an ear hook, the display unit and the ear hook And a supporter for connecting the half mirror to a position near the front of the eye. 9. The display device according to claim 8, further comprising a position adjusting mechanism for adjusting a relative position between the ear hook portion and the display portion. 10. The display device according to claim 8, further comprising a direction adjusting mechanism for adjusting a direction of the half mirror. 11. The display device according to claim 8, wherein only one set of the display unit and the half mirror is provided for monocular viewing.