CN115327779A - Display device - Google Patents

Abstract

The invention discloses a display device which comprises an image generation unit and a transparent substrate, wherein the image generation unit is positioned outside the transparent substrate, the transparent substrate comprises a first interface and a second interface, the image generation unit is used for generating incident rays, the transparent substrate is used for receiving the incident rays and generating refracted rays and reflected rays, a film layer used for selectively transmitting the incident rays, the refracted rays and the reflected rays is arranged on the transparent substrate, and the film layer is arranged on the first interface or the second interface. The invention provides a display device, which can eliminate double images by adopting three different modes, and the double images are eliminated by selecting the wavelength and selecting the functional film, so that most of image light comes from one glass-air interface of a front windshield, the double images are eliminated, the image display effect is better, the experience of a driver is improved, and the driving safety is improved.

Description

Display device

Technical Field

The invention relates to the HUD field, in particular to a display device with an optical structure.

Background

With the continuous development of society, automobiles become indispensable transportation means in daily life of people. However, as the number of automobiles increases, the frequency of occurrence of traffic accidents is also increasing. In order to improve driving safety, the HUD system can assist the vehicle in driving. The vehicle-mounted head-up display (HUD) can prevent a driver from interrupting or losing the grasp of state consciousness due to attention, and the driving safety is improved.

Currently, the head-up HUD system 10 mainly has three modes, namely, direct projection type (Entry HUD), indirect integration type (Combiner HUD), and front windshield integration type (Windows-Shield HUD, also called W-HUD). Wherein the W-HUD takes a front windshield as one element of an optical system and forms a suspended virtual image just ahead of the driver by more than two meters. Thereby can project some important information that driver needs when driving on the windscreen before the car, show that the virtual image fuses with the outdoor scene around the car, the light that fuses the outdoor scene passes through the reflection and intakes driver's eyes, makes the driver see the virtual image that fuses with the outdoor scene to the instrument need not look over by the low head to the driver, the place ahead road surface is watched all the time to eyes, has improved because of the influence of low head to safe driving. However, since the front windshield of the automobile has a certain thickness (as shown in fig. 1), the reflected images of the front and rear faces thereof are misaligned to cause image ghosting. Further, the automotive front windshield is not an ideal flat glass, which is approximated to a spherical surface with a certain radius of curvature in both the horizontal direction and the vertical direction, which further aggravates the above-described ghost image effect.

Ordinary car front windshield generally comprises two-layer approximate flat glass that the middle plastic layer of uniform thickness bonds, and middle plastic layer generally is thermoplastic plastics, and its effect is when the car takes place the striking accident, and even the front windshield is collided garrulous, garrulous glass also can mostly bond on this middle plastic layer, and be unlikely to most to form the garrulous glass that flies to penetrate everywhere to play the effect of protection driver and passenger. The refractive index of the intermediate plastic layer is typically selected to be the same as or close to that of the two glass layers, so that it is believed that no light reflection occurs at the plastic and glass interface or the reflectivity is so low that it is not noticeable. It is believed that when light strikes such an almost transparent automotive front windshield, most of the light will penetrate the front windshield, and only a small portion of the light will be partially reflected at the inner and outer glass-air interfaces of the front windshield. For normal natural light with disordered polarization, the reflectance of the two glass-air interfaces is combined to be around 15%. For reasons of reducing wind resistance or aesthetics, it is common for automotive front windshields to be curved glass, which typically has a radius of curvature of several meters in the lateral and longitudinal directions.

HUD systems based on front windshield reflection are finding increasing use in more and more vehicles because they can provide safer driving environments and better driving experiences. However, with the conventional front windshield described above, since it has two glass-air interfaces that are spatially offset, in the case where the HUD system image display distance is relatively short, the reflection images of the two glass-air reflection interfaces do not coincide, as shown in fig. 1, thereby causing a ghost image of the display image, which affects the driver's view. The image ghost that two reflection interface spatial dislocation brought of this kind can be through increasing HUD system image display distance part solution, however, because two glass-air interface all are similar to the curved surface that has certain curvature radius, same image information light is by these two interfaces reflection back, and the reflection light of two interfaces also can have certain contained angle, and this contained angle also can cause the ghost of display image, and this kind of ghost can't be through HUD system image display distance solution.

As shown in fig. 2, the prior closest patent realizes image ghost elimination by adding a wedge-shaped interlayer in the front windshield so that images reflected by two surfaces of the front windshield are overlapped with each other. According to the scheme, the wedge angle of the wedge-shaped interlayer needs to be accurately controlled, the implementation cost is high, the wedge angle needs to correspond to the virtual image distance of the image generated by the image generation unit, the double image problem of the specific virtual image distance can be solved by the specific wedge angle, and the wedge angle is not universal.

Therefore, a display device is desired to solve the above problems to achieve the elimination of image ghosting.

Disclosure of Invention

In view of the above, the present invention is directed to the defects in the prior art, and a main object of the present invention is to provide a display device, which uses a guiding wavelength selection and a functional film layer to make image light mainly come from an interface of a front windshield, thereby eliminating the ghost image problem of an automobile.

In order to achieve the purpose, the invention adopts the following technical scheme:

the utility model provides a display device, includes image generation unit and transparent substrate, the image generation unit is located outside the transparent substrate, the transparent substrate includes first interface and second interface, the image generation unit is used for generating incident ray, the transparent substrate is used for receiving incident ray and generates refraction light and reflection light, is provided with the rete that is used for carrying out the selectivity to above-mentioned incident ray, refraction light and reflection light on this transparent substrate and sees through, the rete is installed at first interface or second interface.

Preferably, the image generating unit is configured to generate incident light with a first spectral characteristic and carrying image information, a first interface of the transparent substrate is provided with a first film layer, the first film layer has a high reflectivity for the incident light with the first spectral characteristic and a high transmittance for light in a wavelength band other than the first spectral characteristic, and the first spectral characteristic is monochromatic spectrum broadening; the transparent substrate is used for receiving incident light and forming first reflected light, and the first reflected light is finally observed image light.

Preferably, the first film layer is a monochromatic narrow-band reflective filter or a plurality of colors of narrow-band filters.

Preferably, the first spectral characteristic is a spectral broadening of a single color or a spectral broadening of a plurality of single colors.

Preferably, the reflectance of the first film layer with respect to the incident light having the first spectral characteristic is close to 1, and the reflectance with respect to light in a visible light band other than the first spectral characteristic is close to 0.

Preferably, the image generation unit further includes a polarizing element including a linear polarizer or a circular polarizer or a birefringent element.

Preferably, a second film layer is disposed on a second interface of the transparent substrate, the image generating unit is configured to generate incident light, the transparent substrate is configured to receive the incident light and generate a first reflected light and a first refracted light that is emitted to the second interface, the second film layer is configured to weaken the second reflected light generated by the first refracted light at the interface and enhance the second refracted light, so that the first refracted light is converted into the second refracted light through the second interface, the first reflected light is finally observed image light, and the second film layer is an antireflection film or an antireflection film.

Preferably, the first interface of the transparent substrate is provided with a third film layer, the image generating unit is configured to generate incident light, the third film layer is configured to weaken reflected light generated by the incident light at the interface and enhance refracted light, the transparent substrate is configured to generate reflected light at the second interface from the refracted light, the reflected light is finally observed image light, and the third film layer is an antireflection film or an antireflection film.

Preferably, the transparent substrate is a front windshield of a vehicle.

Preferably, the image generating unit includes an optical waveguide unit, the optical waveguide unit includes at least one set of input element, a waveguide substrate and an output element, the input element is used for coupling and inputting image light into the waveguide substrate, the waveguide substrate is used for converting received image light into guided light which propagates in a total internal reflection manner and outputting the guided light to the output element, and the output unit is used for expanding and coupling out the received guided light to form incident light.

The invention solves the technical problem that because the automobile front windshield has a certain thickness, the reflected images of the front face and the rear face of the automobile front windshield have certain dislocation, so that image double images are caused. Further, the automotive front windshield is not an ideal flat glass, which is approximated to a spherical surface with a certain radius of curvature in both the horizontal direction and the vertical direction, which further aggravates the above-described ghost image effect. The most recent patent of current is through adding the wedge intermediate layer in preceding windshield for the images that two surfaces of preceding windshield reflect coincide each other, thereby realize that the image ghost eliminates, and this scheme needs the wedge angle of accurate control wedge intermediate layer, realizes that the cost is higher, and this wedge angle needs to be corresponding with the virtual image distance of the image that the image generation unit generated, and specific wedge angle can only solve the ghost image problem of specific virtual image distance, does not possess the universality. The invention provides a display device, which can eliminate double images by three different modes, and the double images are eliminated by selecting wavelengths and selecting functional films, so that most of image light comes from one glass-air interface of a front windshield, the double images are eliminated, the image display effect is better, the experience of a driver is improved, and the driving safety is improved.

To more clearly illustrate the structural features and effects of the present invention, the following detailed description is given with reference to the accompanying drawings and specific embodiments.

Drawings

Wherein:

FIG. 1 is a schematic diagram of the ghost phenomenon principle;

FIG. 2 is a schematic diagram of a prior art HUD;

FIG. 3 is a diagram of the spectrum of a single color laser source;

FIG. 4 is a reflection curvature line of a reflection filter constructed for the spectral shape of the single color laser light source in FIG. 3;

FIG. 5 is a spectrum of a multi-color laser light source;

FIG. 6 is a reflection curvature line of a reflection filter constructed for the spectral shape of the multi-color laser light source of FIG. 5;

FIG. 7 is a schematic view of a conventional diffractive optical waveguide according to the present invention;

FIG. 8 is a HUD system of the present invention including the diffractive optical waveguide of FIG. 7;

FIG. 9 is a schematic view of the first film layer of the present invention;

FIG. 10 is a schematic view of the second film layer of the present invention during operation;

FIG. 11 is a schematic view of the third film layer according to the present invention.

The attached drawings indicate the following:

10. a HUD system; 11. an image generation unit; 111. a light source; 112. an imaging lens group; 12. image information light; 13. a wave guide plate; 14. a first virtual image; 15. a second virtual image; 20. a transparent substrate; 21. a first glass layer; 22. a plastic layer; 23. a second glass layer; 24. a first interface; 25. a second interface; 26. a first film layer; 27. a second film layer; 28. a third film layer; 30. incident light; 31. a first incident ray; 311. a first light wave; 312. a second light wave; 313. a third light wave; 314. a first curve; 315. a second curve; 316. a third curve; 317. reflecting the curvature line; 32. a second incident ray; 40. refracting the light; 41. a first refracted ray; 42. a second refracted ray; 50. reflecting the light; 51. a first reflected light ray; 60. an eye; 70. a diffractive optical waveguide; 71. a waveguide substrate; 72. a diffractive entrance pupil element; 73. a diffractive pupil expanding element; 74. a diffractive exit pupil element.

Detailed Description

The technical solutions in the embodiments of the present application will be described clearly and completely with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only some embodiments of the present application, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

With the continuous development of society, automobiles become indispensable transportation means in people's daily life, and in order to improve driving safety, the HUD (head up display) system 10 is used for assisting the automobiles in driving, so that the HUD system 10 can prevent drivers from interrupting or losing the understanding of state consciousness due to attention, and driving safety is improved. The head-up HUD system 10 mainly has three modes of a direct projection type (Entry HUD), an indirect integrated type (Combiner HUD), and a front windshield integrated type (Windows-Shield HUD, also called W-HUD), wherein the W-HUD uses the front windshield as one of the elements of the optical system, forms a suspended virtual image beyond two meters in front of the driver, projects some important information onto the front windshield of the automobile, and avoids the driver from looking at the instrument by lowering the head. Because the front windshield has certain thickness and bending degree, the inner surface and the outer surface of the front windshield can be reflected to generate two misaligned virtual images, and the ghost phenomenon is generated.

In order to solve the above-mentioned double image problem caused by the spatial dislocation and bending of the two interfaces of the front windshield, the prior solution is to process the equal-thickness middle plastic layer of the bonded flat glass into a shape with a certain wedge angle and a thick upper part and a thin lower part, so as to adjust the mutual included angle of the two glass air interfaces of the front windshield, so as to realize the superposition of the reflection images of the two interfaces, as shown in fig. 2, and thus eliminate the double image problem of the display image. However, the solution requires precise control of the wedge angle of the intermediate plastic layer, which undoubtedly increases the overall processing cost of the front windshield, and the front windshield with a certain wedge angle can only eliminate images with a certain display distance, but cannot eliminate the ghost images of images with other display distances, and thus has no universality. According to the invention, a functional film, such as an antireflection film or an antireflection film, or a wavelength selective reflection filter is constructed on one glass-air interface of the front windshield, so that the display image information light finally presented to a driver is reflected only from one glass-air interface of the front windshield, and thus, image double images caused by the misalignment of the reflection images of the two glass-air interfaces of the front windshield are eliminated.

In summary, in the prior art, a wedge-shaped interlayer is added in a front windshield, so that two virtual images generated by the front windshield are recombined into one virtual image, thereby eliminating image ghosting, achieving the problem of ghosting which is high in cost and can only meet the specific virtual image distance, and having no universality. The invention provides a display device, which eliminates the reflected light generated on one surface of a front windshield and only keeps the reflected light on the other surface of the front windshield, thereby solving the problem of double images.

As shown in fig. 3 to 11, the image generating device includes an image generating unit 11 and a transparent substrate 20, the image generating unit 11 is located outside the transparent substrate 20, the transparent substrate 20 includes a first interface 24 and a second interface 25, the image generating unit 11 is configured to generate incident light, the transparent substrate 20 is configured to receive the incident light and generate refracted light and reflected light, a film layer is disposed on the transparent substrate 20 and is used for selectively transmitting the incident light, the refracted light and the reflected light, the film layer is mounted on the first interface 24 or the second interface 25, and the transparent substrate 20 is a front windshield of an automobile.

A display device comprises an image generating unit 11 and a transparent substrate 20, wherein the transparent substrate 20 is a front windshield of a vehicle, the image generating unit 11 comprises a light source 111 and an imaging lens group 112, the transparent substrate 20 comprises a first glass layer 21, a plastic layer 22, a second glass layer 23, a first interface 24 and a second interface 25, the plastic layer 22 is sandwiched between the first glass layer 21 and the second glass layer 23, and the first interface 24 and the second interface 25 respectively refer to a first glass layer-air interface and a second glass layer-air interface.

The transparent substrate further comprises an optical waveguide unit, the optical waveguide unit comprises at least one waveguide substrate 71, the optical waveguide unit further comprises at least one input element, the input element is used for optically coupling and inputting the image into the waveguide substrate 71 and forming the guided light which propagates in the waveguide substrate 71 in a total internal reflection mode, the optical waveguide unit further comprises at least one output element, the guided light which propagates in the waveguide substrate 71 is expanded and coupled out, and the incident light 30 is formed. The image generation unit 11 further comprises a polarizing element comprising a linear polarizer or a circular polarizer or a birefringent element.

The transparent substrate comprises a first interface 24 and a second interface 25, the image generating unit 11 is configured to generate incident light 30 with a first spectral characteristic, which carries image information, the first interface 24 of the transparent substrate 20 is provided with a first film 26, the first film 26 has a high reflectivity for the incident light 30 with the first spectral characteristic, and at the same time has a high transmissivity for light in a non-first spectral characteristic band, as shown in fig. 3, the first spectral characteristic may be monochromatic light with a single peak, the first film matched with the first spectral characteristic may be a characteristic that the single peak spectrum in fig. 3 has a reflectivity close to 1, as shown in fig. 4, and the reflection curvature line 317 approaches to 1; the first spectral characteristic may also be a polychromatic spectral characteristic having three peaks of the first light wave 311, the second light wave 312 and the third light wave 313 as shown in fig. 5, and the corresponding first film layer has a first curve 314, a second curve 315 and a third curve 316 corresponding to the first film layer having a reflectivity close to 1 as shown in fig. 6, corresponding to the spectrum of the multi-color laser light source of fig. 5, and the first spectral characteristic is a monochromatic spectral broadening; the transparent substrate 20 is configured to receive an incident light and form a first reflected light 51, where the first reflected light 51 is an image light to be finally observed. The first film layer 26 is a single-color narrow-band reflective filter or a narrow-band filter with multiple colors; the first spectral characteristic is a spectral broadening of a plurality of individual colors. The reflection of the incident light having the first spectral characteristic by the first film layer 26 is close to 1, and the reflectance of the light in the visible light band other than the first spectral characteristic is close to 0.

In particular, the spectral broadening of the image light of the image generation system may be chosen, using a system of light sources 111 with a very narrow spectral broadening, which is the difference between two wavelengths corresponding to half the maximum intensity of the spectral curve, defined as the width of the spectral line of the spectrum, also called half-width. The half width of the emission spectrum is used as a measure of the width of the latent spectral line of the emitted light. Line broadening measurement experiments measure the full width at half maximum of a line. Therefore, the spectral line type is analyzed, the spectral line type is judged to be a Voigt line type, then the line type is used for fitting the experimental image, and finally the spectral line width is calculated. For example, a monochromatic image source with a full width at half maximum of less than 10nm, and the spectrum of the reflected light from the wavelength selective narrow band reflective filter constructed at the first front windshield interface 24 may correspond to the spectrum of the image, so that the image light is reflected with a very high (close to 1) reflectivity when it strikes the front windshield surface, and only a very small portion of the image light is transmitted through the first interface 24 to the second interface 25 to be partially reflected, thereby ensuring that the first interface 24 is approximately a single image information light source. Meanwhile, the reflectivity of the front windshield to the image light can be greatly improved, so that the brightness of the displayed image can be improved, and the power consumption of the whole HUD system 10 is reduced. On the other hand, the narrow-band reflective filter plate has high reflection only in a narrow filtering range corresponding to the spectrum of the image, and the reflectivity can be very low or almost no reflection in other wave bands, so that the front windshield with the narrow-band reflective filter plate still has high transmittance on the image in a natural scene, and an observer cannot observe the natural scene outside the front windshield.

The light wave that can be perceived by human eyes is in the 400-700nm band, and objects in the nature are perceived as different colors by human eyes, which reflect light with different wavelengths in the visible light band, for example, most leaves that we see are green, because most leaves reflect light with a certain spectral width that can be perceived as green by human eyes. Generally, a light ray having a certain spectral width reflected by an object in the natural world has a spectral width ranging from several tens of nanometers to hundreds of nanometers.

Conventional projectors achieve picture presentation similar to color images in the real world by rapid switching and superimposition of three color images. The three initial colors are typically red (R), green (G), and blue (B), referred to as the three primary colors. An illumination system can be constructed by the three-color LED and matched with an image modulator, such as a liquid crystal display or a Digital Micromirror Device (DMD), so as to realize image display; the self-luminous display screen, such as a micro LED display screen, can also be directly constructed by adopting micron-sized LEDs. Generally, the spectral width of light emitted from an LED of a certain color is on the order of tens of nanometers, and when a laser is used as the illumination light source 111, such as an LD laser, the spectral width of a single-color LD laser is generally within 10nm, and image light formed by illumination of the laser light source can be accurately extracted by a narrow-band filter based on wavelength selection. Referring to fig. 3, which shows the spectral shape of a monochromatic laser source 111, a reflective filter for the spectrum can be constructed, as shown in fig. 4, so that the spectral shape has high reflectivity in the wavelength band of the laser spectrum, the curvature line 317 of reflection approaches 1, and the reflectivity outside the wavelength band is substantially 0, i.e. transparent to other wavelength bands, which can be regarded as having no influence on the propagation of light in other wavelength bands. For the RGB light sources 111 of the three colors required for forming a color image, three laser light sources 111 of red, green and blue colors, respectively, may be selected, and the spectral shapes thereof are shown in fig. 5. Similarly, a corresponding multi-wavelength narrow-band filter can be constructed for the spectral shape shown in fig. 5, with a reflectivity close to 1 in the corresponding band range and substantially 0 for the other bands, as shown in fig. 6, so that a targeted extraction of color image light is possible.

The laser light source 111 can be selected as the light source 111 of the image generation unit 11 in the HUD system 10 proposed in the present invention, the incident light from the light source 111 can be reflected and extracted by the narrow band filter film layer constructed on the first interface 24 of the front windshield, and due to the high reflectivity of the second film layer 27, almost all the image can be reflected from the first interface 24, so as to eliminate the image ghost caused by the reflection of the two glass-air interfaces. Further, the second film layer 27 receives an incident light reflectance of approximately 100% compared to the total 15% image light reflectance of a conventional front windshield, which greatly increases the image brightness or reduces the power consumption of the HUD system 10. On the other hand, the film layer of the narrow-band filter has high reflectivity only in a narrow band range, and does not reflect other bands basically, so that the external object images are observed through the front windshield under different influences.

A display device, as shown in FIG. 10, comprises an image generating unit 11 and a transparent substrate 20, wherein the transparent substrate 20 comprises a first interface 24 and a second interface 25, the second interface 25 of the transparent substrate 20 is mostly provided with a second film layer 27, the second film layer 27 is an antireflection film or an antireflection film, the image generating unit is used for generating incident light, the transparent substrate 20 is used for receiving the incident light and generating a first reflected light 51 and a first refracted light 41 which is emitted to the second interface 25, the second film layer 27 is used for weakening the reflected light generated by the first refracted light 41 at the interface and enhancing the second refracted light 42, the first refracted light 41 is mostly converted into a second refracted light 42 by the second interface 25, and the first reflected light 51 is finally observed image light.

Specifically, an antireflection film or an antireflection film may be configured on the second interface 25 of the front windshield, the image light incident on the front windshield is partially reflected at the first interface 24 to form the finally observed image information light, while the second incident light 32 that is not reflected by the first interface 24 of the front windshield is transmitted to the second interface 25 of the front windshield, and since the second interface 25 is configured with the antireflection film or the antireflection film, the interface hardly reflects light, thereby ensuring that the first reflected light 51 generated by the first interface 24 becomes a single image information light source.

The laser light source 111 can be selected as the light source 111 of the image generation unit 11 in the HUD system 10 proposed in the present invention, the incident light emitted from the light source 111 can be extracted by the targeted reflection through the narrow-band filter film layer constructed on the first interface 24 of the front windshield, and due to the high reflectivity of the second film layer 27, almost all the images can be reflected from the first interface 24, so as to eliminate the image ghost caused by the reflection of two glass-air interfaces. Further, the second film layer 27 receives an incident light reflectance of approximately 100% compared to the total 15% image light reflectance of a conventional front windshield, which greatly increases the image brightness or reduces the power consumption of the HUD system 10. On the other hand, the film layer of the narrow-band filter has high reflectivity only in a narrow band range, and does not reflect other bands basically, so that the external object images are observed through the front windshield under different influences.

The HUD system 10 based on the diffraction light waveguide technology will gradually become a product due to its advantages in volume and display effect, and the solution of the present invention can also be applied to the waveguide type HUD system 10.

A display device, as shown in fig. 11, comprising an image generating unit 11 and a transparent substrate 20, wherein the transparent substrate 20 includes a first interface 24 and a second interface 25, and is characterized in that a third film layer 28 is disposed on the first interface 24 of the transparent substrate 20, the third film layer 28 is an antireflection film or an antireflection film, the image generating unit 11 is configured to generate an incident light ray 30, the third film layer 28 is configured to enhance the transmittance of the incident light ray 30 at the first interface 24 or attenuate a reflected light ray, the transparent substrate 20 is configured to make the refracted light ray 40 generate a reflected light ray 50 at the second interface 25, and the reflected light ray 50 is an image light to be finally observed.

Specifically, an antireflection film or an antireflection film may be configured on the first interface 24 of the front windshield so that the incident light 30 incident on the front windshield is hardly reflected at the first interface 24, and when the incident light 30 reaches the second interface 25 of the front windshield, at least partial reflection occurs, and the reflected image light forms the finally observed image light, thereby ensuring that the reflected light 50 generated by the second interface 25 becomes a single image information light source.

Fig. 7 shows a form of a conventional diffractive optical waveguide, which includes a waveguide substrate 71, a diffractive entrance pupil element 72 for forming first transmitted light that is transmitted by total internal reflection within the waveguide substrate 71 by diffracting image light generated by the image generating unit 11, a diffractive pupil element 73 for forming second transmitted light by diffracting the first transmitted light and effecting beam expansion in a first direction, and a diffractive exit pupil element 74 for forming output light by diffracting the second transmitted light and effecting beam expansion in a second direction different from the first direction. Fig. 8 shows a HUD system 10 including the diffractive optical waveguide shown in fig. 6, the HUD system 10 further includes an image generating unit 11 for forming image information rays, the image generating unit 11 includes a light source 111 and an imaging lens group 112, the image information rays 12 produced enter the diffractive pupil expanding element 73 through the diffractive entrance pupil element 72 of the diffractive optical waveguide 70, are expanded and transmitted by the diffractive optical waveguide, are coupled out by the diffractive exit pupil element 74 and are incident on a front windshield, and further, the reflected rays 50 are reflected by the front windshield and enter the eye 60 of the observer.

The principle and the flow of the device are as follows: under the condition of basically not influencing the transmittance of the front windshield, a functional film layer, such as an antireflection film or a wavelength selection type reflection filter, is constructed on the front windshield, so that the reflection of image information light rays on the front windshield of an automobile only occurs on a certain single surface or mostly occurs on a certain single surface, and image double images caused by simultaneous reflection of two surfaces of the front windshield are eliminated.

The invention solves the technical problem that because the automobile front windshield has a certain thickness, the reflected images of the front face and the rear face of the automobile front windshield have certain dislocation, so that image double images are caused. Further, the automotive front windshield is not an ideal flat glass, which approximates a spherical surface with a certain radius of curvature in both the horizontal direction and the vertical direction, which further aggravates the above-described ghost image effect. In the existing closest patent, a wedge-shaped interlayer is added in a front windshield, so that images reflected by two surfaces of the front windshield are superposed with each other, and thus image ghost elimination is realized. According to the scheme, the wedge angle of the wedge interlayer needs to be accurately controlled, the implementation cost is high, the wedge angle needs to correspond to the virtual image distance of the image generated by the image generation unit 11, the double image problem of the specific virtual image distance can be solved by the specific wedge angle, and the wedge angle is not universal. The invention provides a display device, which can eliminate double images by adopting three different modes, and the double images are eliminated by selecting the wavelength and selecting the functional film, so that most of image light comes from one glass-air interface of a front windshield, the double images are eliminated, the image display effect is better, the experience of a driver is improved, and the driving safety is improved.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the technical scope of the present invention, so that any minor modifications, equivalent changes and modifications made to the above embodiments according to the technical spirit of the present invention are within the technical scope of the present invention.

Claims (10)

1. The display device is characterized by comprising an image generation unit and a transparent substrate, wherein the image generation unit is positioned outside the transparent substrate, the transparent substrate comprises a first interface and a second interface, the image generation unit is used for generating incident rays, the transparent substrate is used for receiving the incident rays and generating refracted rays and reflected rays, a film layer used for selectively transmitting the incident rays, the refracted rays and the reflected rays is arranged on the transparent substrate, and the film layer is arranged on the first interface or the second interface.

2. The display device according to claim 1, wherein the image generating unit is configured to generate incident light with a first spectral characteristic for carrying image information, the first interface of the transparent substrate is provided with a first film layer, the first film layer has high reflectivity for the incident light with the first spectral characteristic and high transmittance for light in a wavelength band other than the first spectral characteristic, and the first spectral characteristic is monochromatic spectral broadening; the transparent substrate is used for receiving incident light and forming first reflected light, and the first reflected light is finally observed image light.

3. A display device as claimed in claim 2, characterized in that the first film layer is a monochrome narrow-band reflective filter or a multi-colour narrow-band filter.

4. A display device according to claim 2, wherein the first spectral characteristic is the spectral broadening of a single colour or a plurality of single colours.

5. The display device according to claim 2, wherein the first film layer has a reflectivity of 1 for the incident light having the first spectral characteristic and a reflectivity of 0 for light in a visible light band other than the first spectral characteristic.

6. A display device as claimed in claim 2, characterized in that the image-generating unit further comprises a polarizing element comprising a linear polarizer or a circular polarizer or a birefringent element.

7. The display device according to claim 1, wherein the second interface of the transparent substrate is provided with a second film layer, the image generating unit is configured to generate incident light, the transparent substrate is configured to receive the incident light and generate a first reflected light and a first refracted light toward the second interface, the second film layer is configured to attenuate the second reflected light generated at the interface by the first refracted light and enhance the second refracted light, so that the first refracted light is converted into the second refracted light through the second interface, the first reflected light is finally observed image light, and the second film layer is an antireflection film or an antireflection film.

8. The display device according to claim 1, wherein a third film layer is disposed on the first interface of the transparent substrate, the image generating unit is configured to generate incident light, the third film layer is configured to attenuate a reflected light generated at the interface by the incident light to enhance a refracted light, the transparent substrate is configured to generate a reflected light at the second interface by the refracted light, the reflected light is an image light to be finally observed, and the third film layer is an antireflection film or an antireflection film.

9. A display device according to claim 1, wherein the transparent substrate is a front windshield of a vehicle.

10. A display device according to claim 1, wherein the image generating unit comprises a light guiding unit, the light guiding unit comprising at least one set of input elements for optically coupling in an image into the waveguide substrate, a waveguide substrate for converting received image light into guided light propagating by total internal reflection and outputting to output elements, and output elements for expanding and coupling out the received guided light into incident light.

Images