Patent Description:
Near-eye displays, such as those used in virtual reality (VR), augmented reality (AR), and mixed reality (MR) devices, have become more and more popular as the technology has advanced. A near-eye display may display virtual objects or combine images of real objects with virtual objects. For example, users may view blended images of virtual objects (e.g., computer-generated images (CGIs)) and the surrounding environment at the same time in an AR system, which can be widely used in various fields such as medical, education, logistics, e-Health, and manufacturing. However, when an image of a virtual object is to be transmitted to the user's field of vision (FoV), problems such as low coupling efficiency and insufficient field of view are often caused due to the different wavelengths of different colors. This may cause various undesirable conditions, such as an incomplete image display, an image displayed at the wrong scale, or a color shift. <CIT> describes a waveguide structure having waveguide combiners. <CIT> describes a grating couplers. <CIT> describes a grating couplers. <CIT> describes a diffractive grating having an intermediate expander.

In some embodiments of the present disclosure, the display device (e.g., AR, VE, or MR devices) includes a waveguide structure that includes waveguide combiners stacked one upon the other. At least one input coupler of the waveguide combiner has a gradually changing refractive index, which may effectively improve the coupling efficiency and the user's field of vision (FoV).

In accordance with the embodiments of the present disclosure, a waveguide structure is provided. The waveguide structure includes waveguide combiners stacked one upon the other. Each waveguide combiner includes a waveguide plate and an input coupler disposed on the waveguide plate. The input coupler of at least one waveguide combiner includes first grating pillars, and each first grating pillar has a gradually changing refractive index.

In some embodiments, there may be two or more waveguide combiners.

In some embodiments, each first grating pillar has stacked layers, and there are between three and thirty stacked layers according to the claimed invention.

In some embodiments, the thicknesses of the stacked layers may be different.

In some embodiments, the total height of the stacked layers may be in a range from <NUM> to <NUM>.

In some embodiments, the gradually changing refractive index may have has a maximum refractive index and a minimum refractive index, and the difference between the maximum refractive index and the minimum refractive index is greater than <NUM>, and less than or equal to <NUM>.

In some embodiments, the gradually changing refractive index may be in a range from <NUM> to <NUM>.

In some embodiments, the first grating pillars may be formed in a periodic arrangement, and the period of the periodic arrangement is in a range from <NUM> to <NUM>.

In some embodiments, from a cross-sectional view of the waveguide structure, the profile of each first grating pillar may have two parallel sides.

In some embodiments, the profile of each first grating pillar may be a trapezoid.

In some embodiments, the two parallel sides may be an upper base and a lower base, and
In some embodiments, the lower base may be closer to the waveguide plate than the upper base.

In some embodiments, the lower base may be longer than the upper base.

In some embodiments, the waveguide plate may have a constant refractive index in a range from <NUM> to <NUM>.

In some embodiments, each waveguide combiner may further include an expander disposed on the waveguide plate and adjacent to the input coupler.

In some embodiments, the expander may include second grating pillars, and the distance between two adjacent second grating pillars is constant.

In some embodiments, the second grating pillars may have different widths.

In some embodiments, the second grating pillars may have different thicknesses.

In some embodiments, each waveguide combiner may further include an output coupler disposed on the waveguide plate, wherein the expander may be disposed between the input coupler and the output coupler.

In some embodiments, the waveguide combiners may be used to couple different color lights.

In some embodiments, the different color lights may have wavelengths from <NUM> to <NUM>.

In accordance with some embodiments of the present disclosure, a display device is provided. The display device includes an image source and a waveguide structure configured to couple lights from the image source. The waveguide structure may include optional feature as mentioned above for the first aspect.

In some embodiments, the display device may further include a collimator disposed between the image source and the waveguide structure.

The disclosure can be more fully understood from the following detailed description when read with the accompanying figures. It is worth noting that, in accordance with standard practice in the industry, various features are not drawn to scale.

The following disclosure provides many different embodiments, or examples, for implementing different features of the subject matter provided. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, a first feature is formed on a second feature in the description that follows may include embodiments in which the first feature and second feature are formed in direct contact, and may also include embodiments in which additional features may be formed between the first feature and second feature, so that the first feature and second feature may not be in direct contact.

It should be understood that additional steps may be implemented before, during, or after the illustrated methods, and some steps might be replaced or omitted in other embodiments of the illustrated methods.

Furthermore, spatially relative terms, such as "beneath," "below," "lower," "on," "above," "upper" and the like, may be used herein for ease of description to describe one element or feature's relationship to other elements or features as illustrated in the figures.

In the present disclosure, the terms "about," "approximately" and "substantially" typically mean +/-<NUM>% of the stated value, more typically +/-<NUM>% of the stated value, more typically +/-<NUM>% of the stated value, more typically +/-<NUM>% of the stated value, more typically +/-<NUM>% of the stated value, more typically +/-<NUM>% of the stated value and even more typically +/-<NUM>% of the stated value. The stated value of the present disclosure is an approximate value. That is, when there is no specific description of the terms "about," "approximately" and "substantially", the stated value includes the meaning of "about," "approximately" or "substantially".

It should be understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined in the embodiments of the present disclosure.

The present disclosure may repeat reference numerals and/or letters in following embodiments.

<FIG> is a schematic diagram illustrating a display device <NUM> according to some embodiments of the present disclosure. It should be noted that some components are not presented in their actual structures in <FIG>, and some components of the display device <NUM> have been omitted for sake of brevity. Moreover, the display device <NUM> may be a near-eye display that may be applied in virtual reality (VR), augmented reality (AR), or mixed reality (MR), but the present disclosure is not limited thereto.

Referring to <FIG>, in some embodiments, the display device <NUM> includes an image source <NUM>. For example, the image source <NUM> may be used to display images of virtual objects. The image source <NUM> may be various light sources that may emit different color lights in the range of visible wavelengths (e.g., wavelengths from about <NUM> to about <NUM>), but the present disclosure is not limited thereto. The image source <NUM> may include a liquid-crystal display (LCD), a light-emitting diode (LED), an organic light-emitting diode (OLED), an active matrix organic light-emitting diode (AMOLED), a liquid-crystal on silicon (LCoS), a digital light processing (DLP), RGB laser, any other applicable device, or a combination thereof.

Referring to <FIG>, in some embodiments, the display device <NUM> includes a waveguide structure WS configured to couple lights (e.g., red light R, green light G, and/or blue light B) from the image source <NUM>. It should be noted that <FIG> shows a cross-sectional view of the waveguide structure WS. As shown in <FIG>, in some embodiments, the waveguide structure WS includes a waveguide combiner <NUM> and a waveguide combiner <NUM> that are stacked one upon the other. In particular, the waveguide combiner <NUM> is disposed on the waveguide combiner <NUM>.

As shown in <FIG>, in some embodiments, the waveguide combiner <NUM> includes a waveguide plate <NUM>. For example, the waveguide plate <NUM> may include transparent dielectric material (e.g., glass) that has a constant refractive index in a range from about <NUM> to about <NUM>, but the present disclosure is not limited thereto. Moreover, the waveguide plate <NUM> may be formed by a deposition process, such as a chemical vapor deposition (CVD) process, an atomic layer deposition (ALD) process, a spin coating process, any other applicable process, or a combination thereof, but the present disclosure is not limited thereto.

As shown in <FIG>, in some embodiments, the waveguide combiner <NUM> includes an input coupler <NUM> disposed on the waveguide plate <NUM>. As shown in <FIG>, in some embodiments, the input coupler <NUM> of the waveguide combiner <NUM> includes grating pillars <NUM>, and each grating pillar <NUM> has a gradually changing refractive index. In some embodiments, the gradually changing refractive index is in a range from about <NUM> to about <NUM>.

<FIG> is a partial cross-sectional view illustrating the waveguide plate <NUM> and the grating pillars <NUM> according to some embodiments of the present disclosure. In some embodiments, each grating pillar <NUM> has stacked layers S1 (see <FIG>), and there are between three and thirty stacked layers S1 according to the claimed invention. For example, as shown in <FIG>, each grating pillar <NUM> has stacked layers S1, and there are eleven stacked layers S1, but the present disclosure is not limited thereto. Moreover, the stacked layers S1 may be formed by a deposition process. Examples of the deposition process are described above, and will not be repeated here.

In some embodiments, the stacked layers S1 of the grating pillar <NUM> include different material or have different concentrations, so that the grating pillar <NUM> has a gradually changing refractive index. In some embodiments, the gradually changing refractive index of the grating pillar <NUM> has a maximum refractive index (e.g., the refractive index of the stacked layer S1B at the bottom of the grating pillar <NUM>) and a minimum refractive index (e.g., the refractive index of the stacked layer S1T at the top of the grating pillar <NUM>), and the difference between the maximum refractive index and the minimum refractive index is greater than <NUM>, and less than or equal to about <NUM>.

For example, the refractive index of the stacked layer S1T at the top of the grating pillar <NUM> may be about <NUM>, the refractive index of the stacked layer S1B at the bottom of the grating pillar <NUM> may be about <NUM>, and the difference between the refractive index of the stacked layer S1B and the refractive index of the stacked layer S1T is about <NUM>, but the present disclosure is not limited thereto.

Moreover, the refractive indices of the stacked layers between the stacked layer S1T and the stacked layer S1B are in a range from about <NUM> to about <NUM>. That is, the grating pillar <NUM> has a gradually increasing refractive index from top to bottom according to the claimed invention.

In the embodiment shown in <FIG>, each stacked layer S1 has the same thickness, but the present disclosure is not limited thereto. In some other embodiments, thicknesses of the stacked layers S1 are different. As shown in <FIG>, in some embodiments, the total height H331 of the stacked layers S1 is in a range from about <NUM> to about <NUM>.

As shown in <FIG> and <FIG>, in some embodiments, the grating pillars <NUM> are formed in a periodic arrangement, and the period P33 of the periodic arrangement is in a range from about <NUM> to about <NUM>, such as about <NUM>. In other words, the distance between two adjacent grating pillars <NUM> may be constant, but the present disclosure is not limited thereto.

<FIG> is an enlarged view illustrating the grating pillar <NUM> according to some embodiments of the present disclosure. As shown in <FIG> and <FIG>, from a cross-sectional view of the waveguide structure WS, the profile of each grating pillar <NUM> is a trapezoid. As shown in <FIG>, in some embodiments, the profile of each grating pillar <NUM> has two parallel sides, an upper base UB and a lower base LB, and the lower base LB is closer to the waveguide plate <NUM> than the upper base UB.

As shown in <FIG>, in some embodiments, the lower base LB is longer than the upper base UB. That is, the width WLB of the lower base LB may be greater than the width WUB of the upper base UB, but the present disclosure is not limited thereto. As shown in <FIG> and <FIG>, the lower base LB of the grating pillar <NUM> may be attached to the waveguide plate <NUM>, but the present disclosure is not limited thereto.

<FIG> are different enlarged views illustrating the grating pillar <NUM> according to some other embodiments of the present disclosure. In some embodiments, from a cross-sectional view of the waveguide structure WS, the profile of each grating pillar <NUM> has two parallel sides.

As shown in <FIG>, the profile of each grating pillar <NUM> is a rectangle, the two parallel sides are the upper side US and the lower side LS. As shown in <FIG>, the profile of each grating pillar <NUM> is a parallelogram, the two parallel sides are the upper side US and the lower side LS. As shown in <FIG>, the profile of each grating pillar <NUM> is an isosceles trapezoid, the two parallel sides are the upper base UB and the lower base LB. As shown in <FIG>, the profile of each grating pillar <NUM> is a square, the two parallel sides are the upper side US and the lower side LS. It should be noted that the profile of each grating pillar <NUM> is not limited to <FIG>, which may be changed as needed.

Referring to <FIG>, in some embodiments, the waveguide combiner <NUM> further includes an expander <NUM> disposed on the waveguide plate <NUM> and adjacent to the input coupler <NUM>. For example, the expander <NUM> may use a two-dimensional (2D) pupil expansion technique, which may include grating structures to release the display image, but the present disclosure is not limited thereto.

<FIG> is a partial cross-sectional view illustrating the expander <NUM> according to some embodiments of the present disclosure. Referring to <FIG>, in some embodiments, the expander <NUM> includes grating pillars <NUM>, and the distance between two adjacent grating pillars <NUM> is constant. In other words, in some embodiments, the grating pillars <NUM> are formed in a periodic arrangement, and the period P1 of the periodic arrangement is constant. It should be noted that the grating pillars <NUM> are disposed on the waveguide plate <NUM> in <FIG>, but the waveguide plate <NUM> may be another waveguide plate or a portion of the waveguide plate <NUM>, which may be adjusted as needed.

In some embodiments, the grating pillars <NUM> have different widths. For example, as shown in <FIG>, the width W1 of the grating pillar <NUM>-<NUM> is shorter than the width W2 of the adjacent grating pillar <NUM>-<NUM>, but the present disclosure is not limited thereto.

<FIG> is a partial cross-sectional view illustrating the expander <NUM> according to some other embodiments of the present disclosure. Referring to <FIG>, similarly, the expander <NUM> includes grating pillars <NUM>, and the distance between two adjacent grating pillars <NUM> is constant. In other words, in some embodiments, the grating pillars <NUM> are formed in a periodic arrangement, and the period P1 of the periodic arrangement is constant.

In some embodiments, the grating pillars <NUM> have different thicknesses. For example, as shown in <FIG>, the thickness T1 of the grating pillar <NUM>-<NUM> is less than the thickness T2 of the adjacent grating pillar <NUM>-<NUM>, but the present disclosure is not limited thereto.

As shown in <FIG>, in some embodiments, the waveguide combiner <NUM> includes an output coupler <NUM> disposed on the waveguide plate <NUM>. In more detail, the expander <NUM> is disposed between the input coupler <NUM> and the output coupler <NUM>.

Referring to <FIG>, the waveguide combiner <NUM> has a structure that is similar to the waveguide combiner <NUM>. As shown in <FIG>, in some embodiments, the waveguide combiner <NUM> includes a waveguide plate <NUM> and an input coupler <NUM> disposed on the waveguide plate <NUM>. As shown in <FIG>, in some embodiments, the input coupler <NUM> of the waveguide combiner <NUM> includes grating pillars <NUM>.

<FIG> is a partial cross-sectional view illustrating the waveguide plate <NUM> and the grating pillars <NUM> according to some embodiments of the present disclosure. In some embodiments, each grating pillar <NUM> has stacked layers S2 (see <FIG>), and there are between two and thirty stacked layers S2. For example, as shown in <FIG>, each grating pillar <NUM> has stacked layers S2, and there are eleven stacked layers S2, but the present disclosure is not limited thereto. In some other embodiments, the number of stacked layers S2 in the grating pillar <NUM> is different from the number of stacked layers S1 in the grating pillar <NUM>. Moreover, the stacked layers S2 may be formed by a deposition process. Examples of the deposition process are described above, and will not be repeated here.

In some embodiments, the stacked layers S2 of the grating pillar <NUM> include the same material or have the same concentration, so that the grating pillar <NUM> has a constant refractive index. For example, the refractive index of the stacked layer S2T at the top of the grating pillar <NUM> may be about <NUM>, the refractive index of the stacked layer S2B at the bottom of the grating pillar <NUM> may be about <NUM>, and the difference between the refractive index of the stacked layer S2B and the refractive index of the stacked layer S2T is about <NUM>, but the present disclosure is not limited thereto.

In some other embodiments, the stacked layers S2 of the grating pillar <NUM> are similar to the stacked layers S1 of the grating pillar <NUM>. That is, the stacked layers S2 of the grating pillar <NUM> include different material or have different concentrations, so that the grating pillar <NUM> has a gradually changing refractive index.

In the embodiment shown in <FIG>, each stacked layer S2 has the same thickness, but the present disclosure is not limited thereto. In some other embodiments, thicknesses of the stacked layers S2 are different. As shown in <FIG>, in some embodiments, the total height H431 of the stacked layers S2 is in a range from about <NUM> to about <NUM>.

As shown in <FIG> and <FIG>, in some embodiments, the grating pillars <NUM> are formed in a periodic arrangement, and the period P43 of the periodic arrangement is in a range from about <NUM> to about <NUM>, such as about <NUM>. In other words, the distance between two adjacent grating pillars <NUM> may be constant, but the present disclosure is not limited thereto. In this embodiment, the profile of the grating pillar <NUM> is the same as or similar to the profile of each grating pillar <NUM>, but the present disclosure is not limited thereto. In some other embodiments, the profile of the grating pillar <NUM> is different from the profile of each grating pillar <NUM>, which may be adjusted as needed.

As shown to <FIG>, in some embodiments, the waveguide combiner <NUM> further includes an expander <NUM> disposed on the waveguide plate <NUM> and adjacent to the input coupler <NUM>. Similarly, the expander <NUM> may use a two-dimensional (2D) pupil expansion technique, which may include grating structures to release the display image, but the present disclosure is not limited thereto. In this embodiment, the expander <NUM> has a structure that is similar to expander <NUM>, but the present disclosure is not limited thereto.

In some embodiments, the waveguide combiner <NUM> and the waveguide combiner <NUM> are used to couple different color lights, and the different color lights have wavelengths from about <NUM> to about <NUM> (e.g., visible lights). For example, as shown in <FIG>, the waveguide combiner <NUM> may be used to couple green light G and blue light B, and the waveguide combiner <NUM> may be used to couple red light R and green light G, but the present disclosure is not limited thereto.

As shown in <FIG>, in some embodiments, the display device <NUM> further includes a collimator <NUM> disposed between the image source <NUM> and the waveguide structure WS. The collimator <NUM> may change the diverging light or other radiation from the image source <NUM> into a parallel beam, so that lights form the image source <NUM> may enter the waveguide structure WS smoothly. As shown in <FIG>, the image (lights) from the image source <NUM> may enter the waveguide structure WS through the collimator <NUM>, and then be transmitted to and presented in the user's eyes E.

Compared with the traditional near-eye display, the display device <NUM> according to the embodiments of the present disclosure may effectively improve the coupling efficiency, for example, from about <NUM>% to about <NUM>% due to the waveguide structure WS. Furthermore, the user's field of vision (FoV) may also be improved, for example, from about <NUM>° to about <NUM>°, which is close to the inherent material limitations.

<FIG> is a schematic diagram illustrating a display device <NUM> according to some other embodiments of the present disclosure. Similarly, some components are not presented in their actual structures in <FIG>, and some components of the display device <NUM> have been omitted for sake of brevity.

Referring to <FIG>, the display device <NUM> has a structure that is similar to the display device <NUM>. In some embodiments, the waveguide structure WS of the display device <NUM> further includes a waveguide combiner <NUM> that is stacked on the waveguide combiner <NUM> and the waveguide combiner <NUM>. In more detail, the waveguide combiner <NUM> may be disposed between the waveguide combiner <NUM> and the waveguide combiner <NUM>, but the present disclosure is not limited thereto.

Referring to <FIG>, the waveguide combiner <NUM> has a structure that is similar to the waveguide combiner <NUM> or the waveguide combiner <NUM>. As shown in <FIG>, in some embodiments, the waveguide combiner <NUM> includes a waveguide plate <NUM> and an input coupler <NUM> disposed on the waveguide plate <NUM>. As shown in <FIG>, in some embodiments, the input coupler <NUM> of the waveguide combiner <NUM> includes grating pillars <NUM>.

As shown to <FIG>, in some embodiments, the waveguide combiner <NUM> further includes an expander <NUM> disposed on the waveguide plate <NUM> and adjacent to the input coupler <NUM>. Similarly, the expander <NUM> may use a two-dimensional (2D) pupil expansion technique, which may include grating structures to release the display image, but the present disclosure is not limited thereto. In this embodiment, the expander <NUM> has a structure that is similar to the expander <NUM> or the expander <NUM>, but the present disclosure is not limited thereto.

In some embodiments, the waveguide combiner <NUM>, the waveguide combiner <NUM>, and the waveguide combiner <NUM> are used to couple different color lights, and the different color lights have wavelengths from about <NUM> to about <NUM> (e.g., visible lights). For example, as shown in <FIG>, the waveguide combiner <NUM> may be used to couple blue light B, the waveguide combiner <NUM> may be used to couple green light G, and the waveguide combiner <NUM> may be used to couple red light R, but the present disclosure is not limited thereto.

It should be noted that the number of waveguide combiners is not limited to the embodiment shown in <FIG> (in which there are two waveguide combiners) or the embodiment shown in <FIG> (in which there are three waveguide combiners). In some embodiments, there are two or more waveguide combiners.

In summary, in some embodiments of the present disclosure, the display device (e.g., AR, VE, or MR devices) includes a waveguide structure that includes waveguide combiners stacked one upon the other. At least one input coupler of the waveguide combiner has a gradually changing refractive index, which may effectively improve the coupling efficiency and the user's field of vision (FoV).

The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the scope of the present disclosure. Therefore, the scope of protection should be determined through the claims. In addition, although some embodiments of the present disclosure are disclosed above, they are not intended to limit the scope of the present disclosure.

Claim 1:
A waveguide structure, comprising waveguide combiners (<NUM>, <NUM>, <NUM>) stacked one upon the other, wherein each of the waveguide combiners (<NUM>, <NUM>, <NUM>) comprises:
a waveguide plate (<NUM>, <NUM>, <NUM>); and
an input coupler (<NUM>, <NUM>, <NUM>) disposed on the waveguide plate (<NUM>, <NUM>, <NUM>); wherein the input coupler (<NUM>, <NUM>, <NUM>) of at least one of the waveguide combiners (<NUM>, <NUM>, <NUM>) comprises first grating pillars (<NUM>, <NUM>, <NUM>), and each of the first grating pillars (<NUM>, <NUM>, <NUM>) has a gradually changing refractive index,
characterized in that
each of the first grating pillars (<NUM>, <NUM>, <NUM>) has stacked layers (S1, S2), and the number of stacked layers (S1, S2) is greater than two, and less than or equal to thirty, and
the first grating pillars (<NUM>, <NUM>, <NUM>) have a gradually increasing refractive index from top to bottom.