Display device

Abstract

The present invention provides a display device, which includes a light source, a compensation diffractive optical element that reflects light incident from the light source, and an off-axis reflecting diffractive optical element that reflects the light reflected from the compensation diffractive optical element to the outside, wherein the compensation diffractive optical element adjusts the reflection angle of the light incident from the light source and reflects it to the off-axis reflecting diffractive optical element so that a reflection angle distortion of the light reflected from the off-axis reflecting diffractive optical element is compensated for.

Description

Technical Field

[0001] The present invention claims the benefit of the filing date of Korean Patent Application No. 10-2021-0131868, filed with the Korean Intellectual Property Office on October 5, 2021, and all of its contents are incorporated herein by reference.

[0002] The present invention relates to a display device. Specifically, the present invention relates to a display device configured to include an off-axis reflection diffraction optical element and a compensation diffraction optical element, capable of compensating for chromatic dispersion and reflection angle distortion.

Background Art

[0003] FIG. 1 shows an example of an off-axis reflection diffraction optical element (DOE) used for extended reality video display. FIG. 1(a) is a diagram for explaining chromatic dispersion generated by the off-axis reflection diffraction optical element, and FIG. 1(b) is a diagram for explaining the reflection angle distortion phenomenon generated by the off-axis reflection diffraction optical element.

[0004] As shown in FIG. 1(a), when incident light incident from a light source (e.g., a display panel) is reflected from the off-axis reflection diffraction optical element, the refractive index and transmittance vary depending on the wavelength of the incident light, so chromatic dispersion (dotted arrows, dashed-dotted arrows, and double-dashed-dotted arrows) may occur.

[0005] Also, as shown in FIG. 1(b), when incident light is reflected from the off-axis reflection diffraction optical element, a reflection angle distortion phenomenon may occur in which the angle difference of the incident light (5-degree difference) and the angle difference of the reflected light (3-degree difference) are different from each other.

[0006] When a display panel with a wide wavelength linewidth, such as an LCD (liquid crystal display) panel or an OLED (organic light emitting diodes) panel, is used as a light source, the sharpness of the video may be reduced due to chromatic dispersion and reflection angle distortion.

[0007] To solve the color dispersion problem, a strategy of using an expensive monochromatic light source such as a laser beam scanner (LBS) can be considered. However, LBS has the disadvantage that the eye box, where the image can be seen, is very narrow.

Summary of the Invention

Problems to be Solved by the Invention

[0008] The technical problem to be solved by the present invention is to provide a display device that can solve the reflection angle distortion and color dispersion problems of an off-axis reflective diffractive optical element.

[0009] However, the problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

Means for Solving the Problems

[0010] According to one aspect of the present invention, there is provided a display device including a light source, a compensation diffractive optical element that reflects light incident from the light source, and an off-axis reflective diffractive optical element that reflects the light reflected from the compensation diffractive optical element to the outside, wherein the light reflected from the off-axis reflective diffractive optical element travels in a direction parallel to the traveling direction of the light incident from the light source.

Effects of the Invention

[0011] The display device according to an embodiment of the present invention corrects or compensates for reflection angle distortion and color dispersion, thereby improving the sharpness of the image.

[0012] In addition, since the display device according to an embodiment of the present invention compensates for reflection angle distortion and color dispersion, it is possible to use a display panel such as an LCD panel or an OLED panel having a generally used wide wavelength line width and a wide viewing angle as a light source, and to realize wide versatility and a wide eye box.

[0013] The effects of the present invention are not limited to the effects described above, and the effects not mentioned will be clearly understood by those skilled in the art from the specification of this application and the attached drawings.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0015] In this specification, when a certain part "includes" a certain component, this means that, unless otherwise stated to the contrary, it does not exclude other components, but rather can further include other components.

[0016] Throughout this specification, when a certain member is said to be "on" another member, this includes not only the case where a certain member is in contact with another member, but also the case where there is still another member between the two members.

[0017] Throughout this specification, "A and / or B" means "A and B, or A or B".

[0018] The display device 200 of the present invention is configured to include a compensation diffractive optical element 220, and thus corresponds to a device that can compensate for the reflection angle distortion of light and the chromatic dispersion of light.

[0019] The compensation diffractive optical element 220 reflects the light incident from the light source 210 to the off-axis reflective diffractive optical element 230, and the off-axis reflective diffractive optical element 230 reflects the light reflected from the compensation diffractive optical element 220 back to the outside again.

[0020] The compensation diffractive optical element 220 reflects the light so that the traveling direction of the light reflected from the off-axis reflective diffractive optical element 230 is parallel to the traveling direction of the light incident from the light source. By such a function of the compensation diffractive optical element 220, the reflection angle distortion of the light and the chromatic dispersion of the light can be compensated.

[0021] Hereinafter, the configuration of the display device 200 will be described more specifically.

[0022] FIG. 2 is a diagram for explaining an example of the display device 200 of the present invention that compensates for reflection angle distortion. As shown in FIG. 2, the display device 200 includes a light source 210, a compensation diffractive optical element 220, and an off-axis reflective diffractive optical element 230.

[0023] The light source 210 can irradiate the compensation diffractive optical element 220 with light. Hereinafter, the light irradiated (incident) from the light source 210 to the compensation diffractive optical element 220 is referred to as "incident light".

[0024] The light source 210 can be realized by a display panel having a generally used wide wavelength line width and a wide angular range, such as an LCD (liquid crystal display) panel or an OLED (organic light emitting diodes) panel. In this case, the display device 200 can realize wide versatility and a wide eye box.

[0025] The compensation diffractive optical element 220 can reflect the incident light in the direction of the off-axis reflective diffractive optical element 230. Hereinafter, the light incident from the compensation diffractive optical element 220 to the off-axis reflective diffractive optical element 230 is referred to as "first light".

[0026] The off-axis reflective diffractive optical element 230 can reflect the light (i.e., the first light) that is reflected from and incident on the compensating diffractive optical element 220 to the outside. Hereinafter, the light that is reflected from the off-axis reflective diffractive optical element 230 and travels toward the outside is referred to as "second light". The direction in which the second light travels, i.e., the direction of the light traveling toward the outside, may be the direction toward the observer's pupil.

[0027] The compensating diffractive optical element 220 can adjust the reflection angle of the first light. The adjustment of the reflection angle by the compensating diffractive optical element 220 is for compensating for the reflection angle distortion generated in the off-axis reflective diffractive optical element 230.

[0028] In the example of FIG. 2, incident light having an angular difference of 3 degrees (0 degree to 3 degrees) is reflected as first light having a reflection angle difference of 5 degrees (60 degrees to 65 degrees) by the adjustment of the reflection angle of the compensating diffractive optical element 220, and then is reflected as second light having a reflection angle difference of 3 degrees (0 degree to 3 degrees) again by the reflection of the off-axis reflective diffractive optical element 230.

[0029] Ultimately, since the adjustment of the reflection angle of the compensating diffractive optical element 220 makes the angular difference of the incident light and the angular difference of the second light the same, the reflection angle distortion that occurs when only the off-axis reflective diffractive optical element 230 is used is compensated or corrected.

[0030] FIG. 3 is a diagram for explaining an example related to the display device 200 of the present invention that compensates for chromatic dispersion. As shown in FIG. 3, the display device 200 includes a light source 210, a compensating diffractive optical element 220, and an off-axis reflective diffractive optical element 230.

[0031] The light source 210 can irradiate the compensating diffractive optical element 220 with light (incident light). The light source 210 can be realized by a display panel such as an LCD panel or an OLED panel. In this case, the display device 200 can achieve wide versatility and a wide eye box.

[0032] The compensation diffractive optical element 220 can reflect incident light and make the first light incident in the direction of the off-axis reflective diffractive optical element 230. The off-axis reflective diffractive optical element 230 can reflect the first light and make it travel outside as the second light. The direction in which the second light travels, that is, the direction of the light going outside, may be the direction toward the observer's pupil.

[0033] The compensation diffractive optical element 220 can adjust the chromatic dispersion of the first light. The adjustment of the chromatic dispersion by the compensation diffractive optical element 220 is for compensating the chromatic dispersion generated in the off-axis reflective diffractive optical element 230.

[0034] In the example of FIG. 3, due to the adjustment of the chromatic dispersion of the compensation diffractive optical element 220, lights of different wavelengths (for example, red, green, and blue) are emitted at different angles from each other and reflected as the first light. Thereafter, due to the reflection (chromatic dispersion) from the off-axis reflective diffractive optical element 230, lights of different wavelengths are emitted at the same angle (parallel) from each other and reflected as the second light.

[0035] Ultimately, due to the adjustment of the chromatic dispersion of the compensation diffractive optical element 220, the second light propagates in parallel, and the dispersion-corrected light is incident on the observer's pupil, so the chromatic dispersion that occurs when only the off-axis reflective diffractive optical element 230 is used is compensated or corrected.

[0036] As described above, the embodiments in which the display device 200 compensates for the chromatic dispersion of light and the embodiments in which the display device 200 compensates for the reflection angle distortion of light have been described separately. However, the display device 200 is configured to realize the two embodiments simultaneously. That is, by including the compensation diffractive optical element 220, the display device 200 can not only compensate for the reflection angle distortion of light but also compensate for the chromatic dispersion of light.

[0037] FIG. 4 is a diagram for explaining a comparative experimental example regarding the effect that the display device 200 improves the sharpness of an image.

[0038] (a) and (b) of FIG. 4 show the sharpness of an image by a conventional display device that does not include a compensation diffractive optical element (including only an off-axis reflective diffractive optical element), and (c) and (d) of FIG. 4 show the sharpness of an image by the display device 200 of the present invention that includes a compensation diffractive optical element.

[0039] Referring to FIGS. 4(a) and 4(b), it can be seen that in the conventional display device, since the reflection angle distortion and chromatic dispersion of light generated by the off-axis reflective diffractive optical element are not compensated, the sharpness of the image is relatively reduced.

[0040] Referring to FIGS. 4(c) and 4(d), it can be seen that in the display device 200 of the present invention, since one or more of the reflection angle distortion and chromatic dispersion of light generated by the off-axis reflective diffractive optical element are compensated, the sharpness of the image is relatively increased.

[0041] As described above, the present invention has been described in detail with various examples. However, the examples according to the present invention can be deformed into various different forms. That is, the examples in this specification are provided to more completely explain the present invention to those with average knowledge in the technical field to which the present invention belongs.

[0042] The present invention is not limited to the examples described in this specification, and it goes without saying that various modifications and deformations can be made within the equivalent scope of the technical idea of the present invention and the scope of the claims described below by those with ordinary knowledge in the technical field to which the present invention belongs.

Explanation of Reference Numerals

[0043] 200: Display device 220: Compensation diffractive optical element 230: Off-axis reflective diffractive optical element

Claims

1. A light source that provides diverging light of a single wavelength or multiple wavelengths, a compensation diffractive optical element that reflects light incident from the light source at a plurality of incident angles, and an off-axis reflective diffractive optical element that reflects the light reflected from the compensation diffractive optical element to the outside, the light reflected from the off-axis reflective diffractive optical element travels in a direction parallel to the traveling direction of the light incident from the light source, the light source is an LCD (liquid crystal display) panel or an OLED (organic light emitting diodes) panel, the angular difference of the light incident on the off-axis reflective diffractive optical element is different from the angular difference of the light reflected from the off-axis reflective diffractive optical element, the compensation diffractive optical element compensates so that the angular difference of the light reflected from the off-axis reflective diffractive optical element is the same as the angular difference of the light incident on the compensation diffractive optical element, A display device, characterized in that the light reflected to the outside by the off-axis reflective diffractive optical element is formed larger than the width of the light incident from the light source.

2. the light reflected from the off-axis reflective diffractive optical element is in the same direction as the traveling direction of the light incident from the light source, according to the display device described in Claim 1.

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