HK1153820B - Spectacles-type image display device - Google Patents

Description

Glasses type image display device

Technical Field

The present invention relates to a glasses-type image display device.

Background

In general, as the glasses-type image display device, a device including, for example, an image output unit held on a temple (temple) side of glasses and an eyepiece optical unit held adjacent to a lens of the glasses is suggested. Such an eyeglass-type image display device is configured such that image light of an electronic image to be displayed, which is output from an image output unit, is incident on an eyeball of a viewer through an eyepiece optical unit, whereby the viewer can see the image. In such an eyeglass-type image display device, an electronic image and a background image transmitted through an eyeglass lens are generally superimposed and displayed on an eyeball, and therefore a viewer can see the electronic image (i.e., "see-through image") as a semi-transparent image in his/her field of view.

As a method of realizing a see-through image, there are known an apparatus using a half mirror (half mirror) and a lens or a concave mirror for an eyepiece optical unit, and an apparatus having a hologram optical element provided on a spectacle lens (see, for example, JP2006209144 (a)).

However, when an electronic image is displayed in a see-through manner, if the environment is too bright, the image light intensity of the background image may be too high, and the light intensity of the electronic image may be affected by it to make it difficult to view. Therefore, if the luminance of the electronic image is increased in order to improve visibility, luminance 10 times greater than normal luminance is required. More power is thus consumed, which is economically inefficient. Therefore, in such an environment, it is proposed to reduce the transmittance, in other words, the degree of perspective, of the background image superimposed on the electronic image to provide an image that is easy to see.

For example, there is proposed a glasses-type image display device having an electric switching device (see, for example, JP2830291 (B2)) that employs a liquid crystal shutter as a device for switching between perspective and non-perspective, or having a mechanical mechanism by which a light shielding member made of a material that is a mixture of a transparent material and a colored material can be mounted or dismounted in accordance with the ambient brightness, thereby adjusting the background light (see, for example, JP2001166703 (a)).

Disclosure of Invention

However, when a liquid crystal shutter is used as the electric switching device, the cost of the components required for the liquid crystal shutter is high. In addition, a control structure for controlling the switching is required, which increases the size of the apparatus. Further, with a mechanical mechanism device employing a light shielding member, a viewer needs to mount or dismount the device as the case may be. In addition, if the light shielding member is installed, the external view is blocked over a wide range.

In view of the above, an object of the present invention is to provide a glasses-type image display device capable of easily switching between see-through display and non-see-through display in accordance with ambient brightness without using an electrical mechanism or a mechanical mechanism.

A first aspect of the present invention to achieve the above object is a glasses-type image display device including:

an image output unit for outputting image light of an image to be displayed; and

a reflection unit disposed in a field of view of at least one eyeball of a viewer, the reflection unit adapted to reflect image light output from the image output unit toward the eyeball of the viewer so that the viewer can see a virtual image of the image, wherein a minimum value of a width of a projection section of the reflection unit in an output direction of the image light to the eyeball is smaller than a dark-adaptation (dark-adaptation) pupil diameter of a person and is larger than a light-adaptation (light-adaptation) pupil diameter of the person.

A second aspect of the present invention resides in the glasses-type image display device according to the first aspect, wherein a minimum value of a width of a projection section of the reflection unit in an output direction of the image light is not more than 3.8mm but not less than 1 mm.

A third aspect of the present invention resides in the glasses-type image display device according to the first aspect, wherein a width h of a projection section of the reflection unit in the output direction of the image light satisfies the following equation:

w·d/f+1≤h，

where w is a distance from a pupil position of the viewer to a center point of the reflection unit, f is a focal length of a projection lens provided to form a virtual image in an eyeball of the viewer, and d is a width of an image display element of the image output unit corresponding to a width direction of the projection section, where the units of the parameters h, w, f, d are all mm.

It should be noted that in this specification, "dark adaptation" is defined as a state in which the human eye adapts to darkness in a very dark environment, and "light adaptation" is defined as a state in which the human eye adapts to light in a very bright environment. The human dark-adapted pupil diameter is about 7mm, and the human light-adapted pupil diameter is about 1 mm. It should be noted that the pupil diameter of a human varies from 1mm to 7mm depending on the brightness of the environment, and the average pupil diameter is 4mm in a normal environment.

According to the present invention, the minimum value of the width of the projection section of the reflection unit in the output direction of the image light to the eyeball is smaller than the dark-adapted pupil diameter and larger than the bright-adapted pupil diameter, and therefore the see-through display and the non-see-through display can be easily switched according to the ambient brightness without using an electric mechanism or a mechanical mechanism.

Drawings

Fig. 1 is a partial configuration view schematically illustrating main components of a glasses-type image display device according to a first embodiment of the present invention;

fig. 2 is a diagram illustrating an example of a reflection unit for implementing the present invention;

fig. 3 is a front view of a right eye side of a viewer when the viewer wears the glasses type image display device of fig. 1;

fig. 4(a) is a schematic diagram illustrating switching between a see-through display and a non-see-through display according to a change in pupil diameter in a normal environment;

fig. 4(b) is a schematic diagram illustrating switching between a see-through display and a non-see-through display according to a change in pupil diameter in a very bright environment;

fig. 5(a) is a diagram illustrating a relationship between the size of a plane mirror (plane mirror) of the glasses-type image display device of fig. 1 and the size of a pupil diameter under dark adaptation;

fig. 5(b) is a diagram illustrating a relationship between the size of a plane mirror and the pupil diameter size under bright adaptation of the glasses-type image display device of fig. 1;

fig. 6(a) is a view showing a see-through display image of the glasses-type image display device of fig. 1;

fig. 6(b) is a view showing a non-see-through display image of the glasses-type image display device of fig. 1;

fig. 7 is a diagram illustrating a configuration and a use state of a glasses-type image display device according to a second embodiment of the present invention;

fig. 8 is a diagram illustrating an optical system of the glasses-type image display device of fig. 6;

fig. 9 is a diagram illustrating a configuration and a use state of a glasses-type image display device according to a third embodiment of the present invention;

fig. 10 is a diagram illustrating a viewing angle of a display screen of the portable digital device seen by a viewer;

fig. 11 is a diagram illustrating a viewing angle of a non-see-through area in a very bright environment;

fig. 12(a) is a diagram illustrating a relationship between the size of a plane mirror of a glasses-type image display device according to a fourth embodiment of the present invention and the size of a pupil diameter in a normal environment; and

fig. 12(b) is a diagram illustrating a relationship between the size of a plane mirror and the size of a pupil diameter under bright adaptation in the glasses-type image display device according to the fourth embodiment of the present invention.

Detailed Description

Embodiments of the present invention will be illustrated below with reference to the accompanying drawings.

(first embodiment)

Fig. 1 is a partial configuration view schematically illustrating main components of a glasses-type image display device according to a first embodiment of the present invention. In the figure, eyeballs 2 of his/her right eye when the viewer wears the glasses type image display device 1 are also shown. The glasses-type image display apparatus 1 has a configuration in which an image output unit 5 and a flat mirror 6 constituting a reflection unit are added to glasses mainly composed of a glasses lens 3 and a glasses frame 4.

The eyeglass frame 4 includes a banker (endpiece) 7, temples 9 and hinges 8, the banker 7 being fixed to the eyeglass lenses 3 or the frame of the eyeglass lenses 3 and located at both ends on the front surface of the eyeglasses, the temples 9 being foldably connected to the banker 7 by the hinges 8. The position of the eyeglass type image display device 1 can be fixed relative to the eyeball 2 of the observer by hanging the temple 9 on the ear of the observer and placing the nose pad 10 against the nose of the observer, the nose pad 10 being fixed to the eyeglass lens 3 or the frame thereof.

The image output unit 5 is supported by, for example, a temple 9 of the eyeglass frame 4, has a compact image display element such as a liquid crystal element or an organic EL element and a lens disposed in front of the image display element, and outputs image light of an electronic image to be displayed to the flat mirror 6 through a space between the eyeglass lens 3 and the temple 9.

The flat mirror 6 is held, for example, in the visual field of at least one eyeball (right eye in the drawing) and close to the eyeglass lens 3, and is held, for example, on the surface of the lens portion of the eyeglass lens 3. The angle of the reflecting surface of the flat mirror 6 is adjusted so that the image light output from the image output unit 5 is reflected toward the eyeball 2 of the viewer, and thereby the viewer can see an electronic image displayed as a virtual image. As the plane mirror 6, as shown in fig. 2, (a) a front surface mirror, (b) a rear surface mirror, (c) a mirror embedded in a spectacle lens, and the like can be used. As the front surface mirror and the rear surface mirror, mirrors whose front surface and rear surface are respectively treated with a typical mirror coating (for example, metal deposition or dielectric multilayer film) can be used. At this time, if an opaque mirror is used, a completely non-see-through display can be realized under bright adaptation, and if a transparent half mirror is used, background light can be partially transmitted even in a non-see-through state under bright adaptation. If a mirror embedded in the spectacle lens is used, the angle of inclination can be reduced by refraction between the spectacle lens and the air.

Fig. 3 is a front view of a right eye side of a viewer when the viewer wears the glasses-type image display device of fig. 1. The flat mirror 6 is disposed closer to the image output unit 5 when facing the pupil 11. In addition, the flat mirror 6 is in the shape of a vertically long rectangle, and the horizontal width of a projection cross section in the output direction of the image light to the eyeball is from 1mm to 7mm, preferably from 1mm to 3.8 mm.

Next, switching between the see-through display and the non-see-through display according to the surrounding environment is described. Fig. 4 is a schematic diagram illustrating switching between the see-through display and the non-see-through display according to a change in pupil diameter. Fig. 4 shows the pupil 11 and the optical system of the external light comprising the flat mirror 6 seen from above, the size of the pupil 11 being changed by the iris 12 within the eye. In this figure, the external light reaching the pupil 11 without being blocked by the plane mirror 6 is indicated by a broken-line arrow. Further, fig. 4(a) shows a state in a normal environment, and fig. 4(b) shows a state in a very bright environment and the pupil diameter is minimum.

In the case of the normal environment shown in fig. 4(a), the diameter of the pupil 11 is 4mm, and the distance between the pupil 11 and the flat mirror 6 is about 10 mm. If the horizontal width of the flat mirror 6 is 3.8mm or less as shown in fig. 4(a), light from an external visual field, which is a distance from the pupil 11 to where a person can comfortably see an object, can pass anywhere in the pupil, which is farther than the distance of discriminant vision (typically 250 mm). In this case, the viewer may see an external view (outlview field) and the electronic image as a perspective image within the perspective of the electronic image.

On the other hand, when the surrounding environment is bright and the pupil diameter is minimum, as shown in fig. 4(b), the pupil diameter is contracted to 1mm due to the bright adaptation. At this time, since the horizontal width of the flat mirror (i.e., the width of the projection cross section in the output direction of the image light to the eyeball) is larger than 1mm, there is a region in front of the flat mirror 6 in which light from the external field of view is blocked by the flat mirror 6 and does not reach the pupil 11 as seen by the viewer. Because of this, it is generated in the field of view of the viewer that the external light cannot pass through the non-see-through region 13 of the pupil 11. In the non-see-through region 13, only the electronic image can be seen, and excellent visibility can be obtained without being blocked by a bright external field of view.

Fig. 5 is a diagram illustrating a relationship between the size of a plane mirror and the pupil diameter size of the glasses-type image display device of fig. 1. Fig. 5(a) shows a state in dark adaptation (pupil diameter is maximum), and fig. 5(b) shows a state in bright adaptation (pupil diameter is minimum).

In very dark environments, the electronic image is preferably displayed in a perspective manner with an external field of view. In this case, since the dark-adapted pupil diameter is about 7mm, the pupil diameter is larger than the horizontal width of the flat mirror of 3.8mm, as shown in fig. 5(a), and thereby a see-through display is realized. It should be noted that in this case, if the horizontal width of the flat mirror 6 is less than 7mm (which is a dark adapted human pupil diameter 11), a see-through display can be realized.

On the other hand, in a very bright environment, when an electronic image is displayed in a see-through manner, the brightness of the electronic image is weaker than external light from an external field of view, which results in a very unclear display. Thus, it is preferable to block external light so that an image is displayed in a non-see-through manner. In this case, as shown in fig. 5(b), the diameter of the pupil of the human is about 1mm due to the bright adaptation. Therefore, by providing the horizontal width of the flat mirror 6 larger than 1mm, it is possible to realize a non-see-through display in a distance of a clear vision.

Fig. 6 is a view showing a display image of the glasses-type image display device of fig. 1. Fig. 6(a) shows a see-through display in a normal environment, and fig. 6(b) shows a non-see-through display in a very bright environment. As shown in fig. 6(a), in a normal environment, an electronic image 15 formed by image light output from the image output unit 5 is reflected by the flat mirror 6 and is incident on the eyeball, and this electronic image 15 is superimposed on the external visual field and is displayed in a see-through manner in the visual field of the viewer wearing the eyeglass type image display device 1. On the other hand, as shown in fig. 6(b), in a very bright environment, the pupil 11 becomes smaller due to the bright adaptation, and the background light from the external background is blocked by the flat mirror 6 and is not incident on the pupil. Therefore, only the electronic image 15 from the image output unit 5 is displayed in a non-perspective manner.

As described above, according to the present embodiment, with respect to the flat mirror 6, the projection cross section in the output direction of the image light to the eyeball 2 is in the shape of a vertically long rectangle, and the horizontal width of the projection cross section is in the range of 1mm to 7mm, so that it is possible to switch between the see-through display and the non-see-through display in accordance with a very dark environment (dark adaptation) and a very bright environment (bright adaptation). Further, if the horizontal width of the projection section is in the range of 1mm to 3.8mm, it is possible to display the electronic image in a see-through display manner in a normal environment and to display the electronic image in a non-see-through display manner in a very bright environment. In other words, clear display can be obtained by switching between the see-through display and the non-see-through display according to the ambient brightness.

It should be noted that although the glasses-type image display device 1 illustrated in the present embodiment is configured to display an electronic image for the right eye, it may be configured to display an electronic image for the left eye.

(second embodiment)

Fig. 7 is a diagram illustrating a configuration and a use state of a glasses-type image display device according to a second embodiment of the present invention. Fig. 7 shows the optical path of the image light output from the image output unit 5 and reaching the pupil 11 of the eyeball 2, in addition to the schematic configuration of the eyeglass type image display device 1.

As shown in fig. 7, the glasses-type image display device according to the present embodiment includes a deflection prism 21 connected to the temple 9 and a projection lens 22 connected to an output surface of the deflection prism 21, in addition to the configuration of the glasses-type image display device 1 of fig. 1. The deflection prism 21 and the projection lens 22 may be integrally molded. Further, the apparatus is configured such that the image light output from the image output unit 5 along the temple 9 is incident on the incident surface of the deflection prism 21, and deflected by about 60 degrees, output to the flat mirror 6 provided on the eyeglass lens 3 through the projection lens 22, and reflected by the flat mirror 6 toward the pupil 11.

Further, the image output unit 5 is connected so that its position can be adjusted in the front-rear direction of the eyeglasses along the temple 9, thereby being adjustable according to the diopter of the viewer wearing the device. It should be noted that the angle formed by connecting the central point of the flat mirror 6 and the central point of the pupil 11 is preferably from 60 degrees to 90 degrees.

Fig. 8 is a diagram illustrating an optical system of the glasses-type image display device of fig. 7. The image light output from the display element 23 provided at the image output unit 5 is diffused, is incident on the deflection prism 21 to be deflected, and is condensed by the projection lens 22 so that the width of the light flux of the image light is minimum at the flat mirror 6 and is reflected to the pupil 11. At this time, the flat mirror 6 functions as an aperture stop (aperture stop), and therefore even if it is smaller than the pupil 11, the display element 23, and the projection lens 22, the viewer can see the entire picture of the electronic image without losing a part thereof. Other configurations and functions are the same as those of the first embodiment, and thus, the same reference numerals are assigned to the same configuration elements, and descriptions thereof are omitted.

According to the present embodiment, in addition to the effects of the first embodiment, since the image output unit 5 is configured such that the position thereof can be adjusted along the temple 9, the image output unit 5 outputs image light along the temple 9, and the deflection prism 21 deflects the image light toward the plane mirror 6, it is possible to adjust diopter with respect to an electronic image to be displayed by adjusting the position of the image output unit 5.

(third embodiment)

Fig. 9 is a diagram illustrating a configuration and a use state of a glasses-type image display device according to a third embodiment of the present invention. In the present embodiment, image output units 5l and 5r, deflection prisms 21l and 21r, projection lenses 22l and 22r, and flat mirrors 6l and 6r are provided for the left eyeball 2l and the right eyeball 2r, respectively. Various configurations of the glasses-type image display device for the right eye of fig. 1 are provided for the left eye in addition to the flat mirrors 6l and 6r provided respectively just in front of each eyeball.

In this case, in a state where the viewer faces the front, the electronic image output from the image output unit 5l on the left side and the electronic image output from the image output unit 5r on the right side are superimposed and displayed in the visual field and in front of the viewer, and therefore, in addition to the effects of the second embodiment, it is also possible to display a three-dimensional image in the visual field of the viewer by displaying different images to the right eye and the left eye, for example.

(fourth embodiment)

In the fourth embodiment of the present invention, an image similar to the screen of a portable digital device (e.g., a cellular phone which is generally used) is displayed by a glasses type image display device, the image being set at a position 300mm from the eyeball. Fig. 10 is a diagram illustrating a viewing angle of the display screen 31 of the portable digital device seen by the viewer.

The display screen 31 of a portable digital device that is generally used is about 2.4 inches and in the shape of a vertically long rectangle, and if the distance from the eyeball is 300mm, the viewing angle is about 7 degrees for the short side of the vertically long rectangle and about 9.3 degrees for the long side of the vertically long rectangle.

Fig. 11 is a diagram illustrating the viewing angles of non-see-through regions in a very bright environment and under bright adaptation. In the figure, the pupil diameter is 1mm, and, in order to secure a non-see-through region covering a viewing angle of 7 degrees corresponding to the short side of the display screen of the above-described portable digital device, the minimum value of the width of the projection section of the flat mirror 6 in the output direction of the image light is determined by the following formula:

10mm×tan(3.5゜)×2+1mm=2.2mm

as has been described in the first embodiment, when the reflective flat mirror 6 is viewed in the output direction of the image light to the eyeball 2, if the width of the projection cross section in the horizontal direction (the short side of the flat mirror as a rectangle) is from 1mm to 3.8mm, it is possible to switch between the see-through display and the non-see-through display in accordance with the change between the normal environment and the very bright environment. Therefore, when the width of the short side of the display screen corresponding to the flat mirror 6 is set to be not more than 3.8mm but not less than 2.2mm, a display screen similar to the practically usable size of the portable digital terminal can be displayed in a see-through manner in a normal environment and displayed in a non-see-through manner in a very bright environment.

In other words, it is important to make settings such that the angle of view of the non-see-through region in bright adaptation is larger than the angle of view of the display screen 31 displayed by the glasses-type image display unit. The angle of view θ of the non-see-through region is represented by the formula shown below:

θ=2×arctan{(h-1)/2w}

where h (mm) is the minimum value of the width of the projection section of the reflection unit in the output direction of the image light to the eyeball, w (mm) is the distance from the pupil position to the center of the reflection unit, and the bright-adapted pupil diameter is 1 mm.

On the other hand, the viewing angle ω of the display screen for comparison is represented by the formula shown below:

ω=2×arctan（d/2f）

where d (mm) is the width of the display element in the direction corresponding to the direction of h shown above, and f (mm) is the focal length of the projection lens.

In order to make the angle of view theta of the non-see-through region larger than the angle of view omega, the relationship therebetween is expressed as

ω≤θ，

Thus, the formula shown below is obtained,

d/2f≤(h-1)/2w

w·d/f+1≤h

in addition, in order to realize perspective display in a normal environment, h should satisfy h ≦ 3.8 mm. Combining it with the above formula, the following formula is obtained:

w·d/f+1≤h≤3.8mm

by setting the width of the reflection unit so as to satisfy the above formula, it is possible to realize a see-through display in a normal environment and a non-see-through display covering a display screen area in a bright environment, and excellent visibility is ensured.

Fig. 12 illustrates the relationship between the size of the flat mirror 6 and the pupil diameter size of the present invention. Fig. 12(a) shows a state in a normal environment, and fig. 12(b) shows a state in bright adaptation. It is preferable that the blind area can be eliminated as much as possible in the normal environment by the perspective display. Thus, in fig. 12(a), if the size of the flat mirror 6 is 3.8mm or less, a see-through display can be realized in a range farther than the distance of the clear vision.

On the other hand, in a very bright environment, if the electronic image is displayed in a transparent manner, the brightness of the electronic image may be weaker than the external light from the external visual field, resulting in a very unclear display. Therefore, it is preferable to block external light to display in a non-see-through manner. If the width of the projection section of the flat mirror 6 in the output direction of the image light is 2.2mm or more, a see-through display in the range of a viewing angle of 7 degrees, which is an actual display size, can be realized.

In the present embodiment, the width of the projection cross section of the flat mirror 6 in the output direction of the image light is not more than 3.8mm but not less than 2.2mm, whereby it is possible to switch between the see-through display and the non-see-through display according to the surrounding environment as shown in fig. 6 of the first embodiment. At this time, it is possible to secure a display area equivalent to the portable digital device as a display screen in the field of view of the viewer.

It should be noted that the present invention is not limited to the above-described embodiments, and various modifications and changes can be made. For example, although the image output unit of the glasses type image display device is connected to the temple, it may be connected to the dealer head, for example.

In each of the embodiments, the plane mirror as the reflection unit has a vertically long rectangular shape. However, it may be a laterally long rectangle. In addition, the reflection unit is not limited to a plane mirror, and the optical system may be configured using a concave mirror. In this case, the lens of the image output unit may be omitted. Further, the shape of the two-dimensional image to be displayed is not limited to a vertically long rectangle, and it may be a laterally long shape irrespective of the shape of the reflection unit.

The present application claims priority from japanese patent application No.2009-209749, filed on 9/10 of 2009, the contents of which are incorporated herein by reference.

Claims (3)

1. An eyeglass-type image display device, comprising:

an image output unit for outputting image light of an image to be displayed; and

a reflection unit provided in a field of view of at least one eyeball of a viewer, the reflection unit being provided to reflect the image light output from the image output unit toward the eyeball of the viewer so that the viewer can see a virtual image of the image, wherein,

a minimum value of a width of a projection section of the reflection unit in an output direction of the image light to the eyeball is smaller than a dark-adapted pupil diameter of a person, which is 7mm, and larger than a bright-adapted pupil diameter of a person, which is 1 mm.

2. The glasses-type image display device according to claim 1, wherein a minimum value of a width of the projection section of the reflection unit in the output direction of the image light is not more than 3.8mm but not less than 1 mm.

3. The glasses-type image display device according to claim 1, wherein a width h of the projection section of the reflection unit in the output direction of the image light satisfies the following equation:

w·d/f+1≤h,

where w is a distance from a pupil position of the viewer to a center point of the reflection unit, f is a focal length of a projection lens provided to form the virtual image in the eyeball of the viewer, and d is a width of an image display element of the image output unit corresponding to a width direction of the projection section, where units of parameters h, w, f, d are all mm.