WO2015154643A1

WO2015154643A1 - Transmissive glasses display

Info

Publication number: WO2015154643A1
Application number: PCT/CN2015/075865
Authority: WO
Inventors: 肖雪; 谭小地; 林枭
Original assignee: 北京理工大学
Priority date: 2014-04-09
Filing date: 2015-04-03
Publication date: 2015-10-15
Also published as: CN103941398B; CN103941398A

Abstract

The present invention relates to a display device, and specifically provided is a transmissive glasses display. Aiming at the defects that the existing transmissive glasses display of a reflection waveguide device has low efficiency of light energy utilization and is uncomfortable to wear because of overlarge waveguide thickness, a structure comprising a light guide plate, and an incident reflection device (3) and at least one display reflection device (4, 5, 6) which are arranged in the light guide plate is formed by taking some reflection films having very high reflectivity at the light wave band in which an incident image is located and very low reflectivity at other light wave bands as reflection devices, and is used for conducting total reflection propagation on the incident image between two parallel surfaces (1, 2) inside the light guide plate after the incident image is reflected by the incident reflection device and conducting emergent display on same after the incident image is reflected at the at least one display reflection device. The efficiency of light energy utilization of a glasses display can be improved, the optical performance is stable, and the structure is made compact at the same time, thereby reducing the overall weight of a system.

Description

Transmissive glasses display

Technical field

The present invention relates to display devices, and in particular to a transmissive glasses display.

Background technique

A head mounted display is an image display device that is worn on the head and is typically placed on the user's head with a cap, helmet or spectacle frame as a support. It mainly consists of four parts: image information display source, circuit control system, optical imaging system, and fixed support structure. It uses an optical system to project an image from a microdisplay into the person's eyes as an enlarged virtual image. The head-mounted display is a new product in modern portable mobile display devices, and has wide applications in augmented reality, virtual reality image display, and stereoscopic display.

As the most lightweight wearable display device in the head-mounted display, the glasses display can be applied not only in the military, but also in the industrial, medical and daily life, expanding the application field of the traditional head-mounted display. . The glasses display can be roughly divided into two types: a transmissive type and a direct view type. The transmissive glasses display can be used as an enhanced display device, and can not only image an image generated by a small two-dimensional display through an optical system but also image. In front of the eye, it is also possible to superimpose virtual objects or information on real scenes, which is safer and more widely used than direct-view glasses displays.

The reflective waveguide is guided by a light guiding substrate embedded in the reflective optics, which is a technical means that has a prominent advantage in the transmissive glasses display. Compared with off-axis curved mirrors, holographic waveguides, diffractive waveguides or polarized waveguides, there is no problem of color unevenness, and it can use a plastic substrate, which can greatly reduce the quality of the device while reducing the cost. In addition, there is no special requirement for the projection device (such as a polarized waveguide, it is necessary to use a polarized microdisplay as a micro projector).

However, in the prior art, a transmissive spectacle display using a reflective waveguide device generally employs a conventional transflective film embedded waveguide. Such a structure is on the one hand due to the transflective film The use of light energy utilization is low, and on the other hand, the size of the reflective device is proportional to the field of view and the moving frame of the eye, which forces the thickness of the waveguide to increase, so that the mass and volume of the entire device are increased, and the wearing is uncomfortable.

Summary of the invention

The invention provides a transmissive glasses display, which can improve the light energy utilization rate and optical performance stability of the glasses display, make the structure compact, and reduce the overall quality of the system.

In one aspect, the present invention provides a transmissive glasses display comprising:

Light guide plate;

An incident reflective device disposed in the light guide plate;

At least one display reflective device disposed in the light guide plate;

The transmissive spectacle display is configured to cause an incident image to be reflected by the incident reflective device, totally reflected between two parallel faces on the inner side of the light guide plate, and reflected at the at least one display reflective device to be emitted and displayed;

The reflecting surface of the incident reflecting device and the at least one display reflecting device is a plane or a curved surface, and a partial reflection film is disposed thereon;

In the visible light band, the reflectance of the partially reflective film is not less than 0.2 in a plurality of wavelength bands in which the incident image is not more than 100 nm, and the reflection of the partially reflective film in other wavelength bands in the visible light band The rate is not more than 0.4.

Optionally, the light guide plate is made of a transparent material.

Optionally, the partially reflective film on the incident reflective device is a negative filter, and the reflectance of the negative filter is not less than 0.8 in a plurality of wavelength bands where the incident image is not more than 100 nm.

Optionally, along the incident image propagation direction, a partial reflection film on the at least one display reflective device sequentially increases in reflectance in a plurality of wavelength bands in which the incident image is not larger than 100 nm.

Optionally, the at least one display reflective device is specifically three. According to the incident image propagation direction, the reflectances of the three display reflective devices in a plurality of wavelength bands of the incident image where the width is not more than 100 nm are 0.2-0.4, 0.4-0.6 and 0.8-1.0.

Alternatively, the partially reflective film is made of an inorganic material.

Optionally, the reflective surfaces of the at least one display reflective device are parallel to each other.

Optionally, the reflective surface of the incident reflective device is symmetrical with respect to a normal of the light guide plate of the reflective surface of any one of the display reflective devices.

Optionally, the acute angle θ between the reflective surface of the display reflective device and the light guide plate, the refraction angle α when the incident image is incident on the light guide plate, and the refractive index n of the light guide plate satisfy:

Where n ₀ is the vacuum refractive index.

Optionally, the acute angle θ between the reflective surface of the display reflective device and the light guide plate is between 20° and 45°.

The present invention provides a transmissive glasses display that uses a partially reflective film having a high reflectance in a narrow band in which an incident image is located, and a high transmittance in the remaining bands (of course, in the visible light range) The incident image can be specifically reflected on the reflective surface provided with the partial reflection film, so that the incident image propagates between the light guide plate and the reflective device, and finally reflects on the reflective surface of each display reflection device and is refracted into the human eye. That is to say, only the light in the narrower band where the incident image is located can be totally reflected and propagated through the incident reflection device into the light guide plate, and then imaged; while the other wavelengths of light are mostly transmitted on the reflective surface of these reflective devices. Therefore, the light of the external scene can be transmitted, thereby achieving a transmissive display.

Compared with the background art, the reflectance on a specific wavelength band of these partial reflection films can reach a very high (close to 100%) level, so the light intensity loss during the imaging process is small, and the light energy utilization of the display can be improved. rate. Moreover, such a partially reflective film reflecting device can perform the function of its eyeglass display in a very compact structure with few reflecting devices, greatly reducing the thickness of the entire light guiding plate while reducing the overall quality of the system.

Of course, implementing any of the products or methods of the present invention does not necessarily require all of the advantages described above to be achieved at the same time.

DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the description of the prior art will be briefly described below. Obviously, the drawings in the following description are Some embodiments of the present invention may also be used to obtain other drawings based on these drawings without departing from the art.

1 is a schematic structural view of a transmissive glasses display according to an embodiment of the present invention;

2 is a simplified schematic diagram of an RGB image incident from a micro projector to a light guide plate in one embodiment of the present invention;

3 is a schematic view showing an optical path of external light passing through a light guide plate according to an embodiment of the present invention;

Figure 4 is a side elevational view of a waveguide in a preferred embodiment of the invention.

detailed description

The technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. It is a partial embodiment of the invention, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

Embodiments of the present invention provide a transmissive glasses display, see FIG. 1, including:

a light guide plate (including an upper surface 1 and a lower surface 2);

An incident reflective device (3) disposed in the light guide plate;

At least one display reflecting device (4, 5, 6 disposed in the light guide plate, only three of which are exemplified in the figure);

The transmissive spectacle display is configured to totally reflect the incident image through the incident reflection device (3), and then totally reflect between the two parallel faces (1, 2) inside the light guide plate, and at least one display reflective device (4, 5, 6) After the reflection, the exit display;

The reflecting surface of the incident reflecting device (3) and the at least one display reflecting device (4, 5, 6) may be a plane or a curved surface, and a partial reflection film is disposed thereon;

In the visible light band, the reflectance of the partially reflective film is not less than 0.2 in a plurality of wavelength bands in which the incident image is not more than 100 nm, and is in other wavelength bands in the visible light band. The partial reflection film has a reflectance of not more than 0.4.

Wherein, the incident angle of the incident image and the tilt angle of each of the reflective devices are such that the total reflection condition is satisfied when the light propagates in the light guide plate.

It can be seen that the light guide plate having such a structure is used as a lens of the left and right eyes of the eyeglass display, and a binocular dual source display method is used, thereby forming a glasses display having two image sources and two sets of optical systems. Of course, it is also possible to use a lens, a display source, a single-eye display method, or a two-lens lens to share a display source, etc., based on the same inventive concept, which obviously does not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Taking a common RGB display as an example, referring to Figure 2, the image light (three monochromatic lights of red, blue, and green) is emitted from the microdisplay (7), passes through the aperture stop (8), and passes through the collimating lens ( 9) After convergence, after incident on the lower surface (2) of the light guide plate, refraction occurs first, and then reaches the reflection surface of the incident reflector (3). Because the reflective surface of each reflector is provided with a partial reflection film with high reflectivity of light in the wavelength band (red, blue, green) of the incident image and high transmittance to other wavelengths, the red, blue and green in the incident light The three-color light is reflected here to the lower surface (2) of the light guide plate, and is reflected up and down in the form of total reflection. The incident light of other wavelength bands will directly pass through the reflective surface of the incident reflector without entering the total reflection optical path of the light guide plate.

Moreover, since at least one display reflection device is employed in the scheme, the field of view of the glasses display can be adjusted by changing the number of display reflection devices. Regardless of the display effect difference caused by the display of the spacing between the reflective devices, a larger number of display reflective devices can bring a larger field of view range, and the intensity of the light emitted from each of the partial reflection surfaces will be different. Conversely, a smaller number of display reflective devices can make the intensity of the outgoing light on each of the partially reflective surfaces high, but the field of view is limited.

Based on the beneficial effects, such a transmissive glasses display can improve the light energy utilization rate of the glasses display, make the structure compact, and reduce the overall quality of the system.

Preferably, the light guide plate is made of a transparent material. Referring to Fig. 3, the external light can be directly transmitted through the light guide plate without greatly affecting the external image seen by the human eye through the glasses.

Preferably, the partially reflective film on the incident reflective device is a negative filter, and the reflectance of the negative filter is not less than 0.8 in a plurality of wavelength bands in which the incident image is not more than 100 nm. A negative filter is an interference film system that removes (reflects) a certain wavelength band from the spectral range and connects two high transmission bands on both sides of the reflection band. Its characteristics include very small transmittance, a wavelength corresponding to a minimum value of transmittance, and a half width of a reflection band region. The narrow-band high-reflection film is a negative filter in which the half-width of the reflection band region is extremely narrow and the minimum transmittance is close to 100%. Such an arrangement can greatly reduce the light intensity loss of the image from the incident to the exit, and further improve the utilization of light energy.

Preferably, along the incident image propagation direction, the partial reflection film on the at least one display reflection device sequentially increases in reflectance in a plurality of wavelength bands in which the incident image is not larger than 100 nm. With such a setting, the incident image can be partially reflected on the plurality of display reflection devices, so that the reflectances from small to large can be designed such that the parallel light incident to the human eye is the intensity of each segment. Evenly, the display is better. For example, more preferably, when the display reflective device is specifically three, the reflectance can be set to about 33%, about 50%, and about 100%, respectively (specifically, 0.2-0.4, 0.4-0.6, and 0.8-1.0). ), so that each reflection can reflect about 1/3 of the light intensity, so that the emitted parallel light intensity is evenly distributed. Experiments have shown that when the display reflective device is set to three, the display effect is better than one or more.

Preferably, the partially reflective film is made of an inorganic material, and the partially reflective film made of an inorganic material has better optical stability, and is more suitable for the eyeglass display provided by the embodiment of the present invention.

In order to more clearly illustrate the technical solution of the present invention, a more detailed and specific preferred embodiment is proposed on the basis of any of the above-mentioned transmissive glasses displays.

Referring to FIG. 4, a partially reflective film is embedded in the light guide plate as a reflection device, and the light interference principle is used to achieve higher reflectance of one or several bands of light, and other rays have higher transmittance. In this configuration, the light incident on the image and the upper and lower surfaces (1, 2) of the light guide plate are at an acute angle θ, and the angle of reflection on the lower surface (2) of the light guide plate is α, which is partially reflected at the incident reflection device. The incident angle on the film (3) is (θ - α). The partial reflection surfaces (4, 5, 6, similarly, the number of examples) of the display device are shown and displayed, and the acute angle between the upper and lower surfaces (1, 2) of the light guide plate is also θ.

That is, the reflecting surfaces of the at least one display reflecting device are parallel to each other, and the reflecting surface of the incident reflecting device is symmetrical with respect to a normal line of the light guide plate with respect to the reflecting surface of any one of the display reflecting devices.

Overall, the transmissive glasses display works as follows: the light of the image (three monochromatic lights of red, blue, and green) is emitted from the microdisplay (7), passes through the aperture stop (8), and is aligned. After the straight lens (9) is concentrated, it is incident on the lower surface (2) of the light guide plate, and then refracts, and then reaches the reflecting surface of the incident reflector (3). After reflection through the narrow-band high-reflex surface (3), most of the light is reflected, and a small portion of the light is transmitted. The reflected light reaches the lower surface (2) of the light guide plate, and is totally reflected forwardly between the upper and lower surfaces (1, 2); after the surface (4, 5, 6) of the partially reflective film, part of the light is transmitted, and some light is reflected. The reflected light is refracted by the light guide plate and then emerges to reach the human eye. The external light directly enters the light guide plate. After passing through the surface of the partially reflective film (4, 5, 6), most of the light is transmitted, and a small portion of the light is reflected, and the transmitted light enters the human eye.

In order to satisfy the total reflection condition, it is necessary to make the acute angle θ between the reflective surface of the display reflection device and the light guide plate, the refraction angle α when the incident image is incident on the light guide plate, and the refractive index n of the light guide plate satisfy:

Where n ₀ is the vacuum refractive index.

Preferably, the vicinity of θ=20° to 45° is selected, which has a good experimental effect.

Moreover, such a parallel reflection surface at a certain interval of the same inclination angle can increase the width of the outgoing beam, thereby increasing the range of eye observation for use by human eyes of different interpupillary distances. Among them, the distance between the partial reflection films (4, 5, 6) can be set according to the inclination angle of the desired partial reflection film. Since the spacing of the exiting parallel beams is determined by this distance, the distance of the outgoing beams can be adjusted by adjusting this distance. Similarly, a larger field of view can also be obtained by providing a plurality of display reflective devices.

The preferred solution is mainly to set the reflecting surface of the reflective device to be a series of planes parallel to each other. In addition to the beneficial effects described above, such a structure can greatly reduce the thickness of the entire light guiding plate and reduce the overall system. The quality, in the case of the same thickness, increases the range of motion of the field of view and the eye. Moreover, the symmetrical design of the incident and exit structures can eliminate the aberration caused by chromatic aberration, color shift and temperature deformation, and improve the image quality. The reflective film is made of an inorganic material to improve the optical stability of the material.

In summary, the present invention proposes a lightweight, compact, and highly reliable transmission spectacles The display, which can perform the function of its glasses display in a very compact structure with few reflective devices, greatly reduces the thickness of the entire light guide plate while reducing the overall quality of the system.

The above technical solution can be implemented in the display field, and can provide a light-weight, compact and reliable transmissive glasses display, and can complete the glasses display in a very compact structure with few reflective devices. The function makes the thickness of the entire light guide plate greatly reduced, and at the same time reduces the overall quality of the system, and has industrial applicability.

In the description of the present invention, the orientation or positional relationship of the terms "upper", "lower" and the like is based on the orientation or positional relationship shown in the drawings, and is merely for convenience of description of the present invention and simplified description. It is not intended or implied that the device or component that is referred to has a particular orientation, is constructed and operated in a particular orientation, and thus is not to be construed as limiting the invention. Unless specifically stated and limited, the terms "mounted," "connected," and "connected" are used in a broad sense, and may be, for example, a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection, It can also be an electrical connection; it can be directly connected, or it can be connected indirectly through an intermediate medium, which can be the internal connection of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood on a case-by-case basis.

It should also be noted that, in this context, relational terms such as first and second, etc. are used merely to distinguish one entity or operation from another entity or operation, without necessarily requiring or implying such entities or operations. There is any such actual relationship or order between them. Furthermore, the term "comprises" or "comprises" or "comprises" or any other variations thereof is intended to encompass a non-exclusive inclusion, such that a process, method, article, or device that comprises a plurality of elements includes not only those elements but also Other elements, or elements that are inherent to such a process, method, item, or device. An element that is defined by the phrase "comprising a ..." does not exclude the presence of additional equivalent elements in the process, method, item, or device that comprises the element.

The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to be limiting; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that The technical solutions are described as being modified, or equivalent to some of the technical features, and the modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

A transmissive glasses display, comprising:

Light guide plate;

An incident reflective device disposed in the light guide plate;

At least one display reflective device disposed in the light guide plate;

The transmissive spectacle display is configured to cause an incident image to be reflected by the incident reflective device, totally reflected between two parallel faces on the inner side of the light guide plate, and reflected at the at least one display reflective device to be emitted and displayed;

The reflecting surface of the incident reflecting device and the at least one display reflecting device is a plane or a curved surface, and a partial reflection film is disposed thereon;

In the visible light band, the reflectance of the partially reflective film is not less than 0.2 in a plurality of wavelength bands in which the incident image is not more than 100 nm, and the reflection of the partially reflective film in other wavelength bands in the visible light band The rate is not more than 0.4.
The transmissive eyeglass display according to claim 1, wherein the light guide plate is made of a transparent material.
The transmissive spectacle display according to claim 1, wherein the partial reflection film on the incident reflection device is a negative filter, and the reflectance of the negative filter is at a plurality of widths of the incident image. Not less than 0.8 in the band of not more than 100 nm.
The transmissive spectacle display according to claim 1, wherein a portion of the reflective film on the at least one display reflecting device is at a width of not more than 100 nm at a position of the incident image along the incident direction of the incident image. The reflectance in the band increases in turn.
The transmissive spectacle display according to claim 4, wherein the at least one display reflecting device is specifically three, and in the direction of propagation of the incident image, three display reflecting devices are located at the incident image The reflectances in the bands having a width of not more than 100 nm are sequentially 0.2-0.4, 0.4-0.6, and 0.8-1.0.
The transmissive spectacle display according to any one of claims 1 to 5, wherein the partially reflective film is made of an inorganic material.
The transmissive spectacle display according to any one of claims 1 to 5, wherein the reflecting surfaces of the at least one display reflecting device are parallel to each other.
The transmissive spectacle display according to claim 7, wherein the reflecting surface of the incident reflecting means is symmetrical with respect to a normal of the light guiding plate of the reflecting surface of any one of the display reflecting means.
The transmissive spectacle display according to claim 7, wherein the display reflection device has an acute angle θ between the reflection surface and the light guide plate, a refraction angle α when the incident image is incident on the light guide plate, and a refractive index of the light guide plate. n meets:

Where n 0 is the vacuum refractive index.
The transmissive spectacle display according to claim 9, wherein an acute angle θ between the reflecting surface of the display reflecting device and the light guide plate is between 20° and 45°.