Display device

Abstract

There is provided a display device including: a display unit including a first surface on which an image is displayed and a second surface opposite to the first surface; a geometric phase lens; a polarized light changing element located between the first surface of the display unit and the geometric phase lens; and a lens portion between the polarized light changing element and the geometric phase lens, and including a half mirror, a lens, and a reflector.

Description

Technical Field

[0001] The present disclosure generally relates to display devices, optical systems, and head-mounted display devices. Background Art

[0002] Recently, as interest in information displays has increased, research and development of display devices have been ongoing. Summary of the Invention

[0003] The embodiments provide a display device and a head-mounted display device, which can reduce or minimize the volume of a focus-adjustable optical system and can reduce the weight of the focus-adjustable optical system, thereby reducing or minimizing user fatigue.

[0004] According to aspects of the present disclosure, a display device is provided, comprising: a display unit including a first surface on which an image is displayed and a second surface opposite to the first surface; a geometric phase lens; a polarization light changing element located between the first surface of the display unit and the geometric phase lens; and a lens portion located between the polarization light changing element and the geometric phase lens and including a half-mirror, a lens, and a reflector.

[0005] The half mirror, the lens, and the reflector may be arranged sequentially.

[0006] The polarization light changing element may include a linear polarizer, a first half-wave plate, and a first quarter-wave plate.

[0007] The first half-wave plate may be located between the linear polarizer and the first quarter-wave plate.

[0008] The reflector may include a linear polarization dependent reflector.

[0009] The lens portion may further include a second quarter wave plate located between the lens and the linear polarization dependent reflector.

[0010] The display device may further include a third quarter-wave plate located between the linear polarization dependent reflector and the geometric phase lens.

[0011] The reflector may comprise a circular polarization dependent reflector.

[0012] The display device may further include a second half-wave plate located between the lens portion and the geometric phase lens.

[0013] According to another aspect of the present disclosure, an optical system is provided, comprising: a linear polarizer; a geometric phase lens; a first half-wave plate located between the linear polarizer and the geometric phase lens; a first quarter-wave plate located between the first half-wave plate and the geometric phase lens; a half-reflective mirror located between the first quarter-wave plate and the geometric phase lens; a lens located between the half-reflective mirror and the geometric phase lens; a reflector located between the lens and the geometric phase lens; and a second half-wave plate located between the reflector and the geometric phase lens.

[0014] The reflector may comprise a circular polarization dependent reflector.

[0015] The reflector may include a linear polarization dependent reflector.

[0016] The optical system may further include a second quarter wave plate located between the lens and the linear polarization dependent reflector.

[0017] The optical system may further include a third quarter wave plate located between the second half wave plate and the geometric phase lens.

[0018] The first half-wave plate and the second half-wave plate may include a first substrate, a second substrate, and liquid crystal located between the first substrate and the second substrate.

[0019] According to another aspect of the present disclosure, a head-mounted display device is provided, which includes: a display unit; a geometric phase lens configured to be located between the display unit and a pupil of a user; a linear polarizer located between the display unit and the geometric phase lens; a first half-wave plate located between the linear polarizer and the geometric phase lens; a first quarter-wave plate located between the first half-wave plate and the geometric phase lens; and a lens portion located between the first quarter-wave plate and the geometric phase lens and including a half-mirror, a lens, and a reflector.

[0020] The reflector may include a linear polarization dependent reflector.

[0021] The lens portion may further include a second quarter wave plate located between the lens and the linear polarization dependent reflector.

[0022] The head-mounted display device may further include a third quarter-wave plate located between the linear polarization-dependent reflector and the geometric phase lens.

[0023] The reflector may comprise a circular polarization dependent reflector. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Embodiments will now be described more fully hereinafter with reference to the accompanying drawings. Although the embodiments may be embodied in different forms, they should not be construed as limited to the descriptions set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the example embodiments to those skilled in the art.

[0025] In the accompanying drawings, dimensions may be exaggerated for clarity of illustration. It will be understood that when an element is referred to as being "between" two elements, it can be the only element between the two elements, or one or more intervening elements may be present. Like reference numerals refer to like elements throughout.

[0026] Figure 1 is a perspective view schematically illustrating a display device according to one or more embodiments of the present disclosure.

[0027] Figure 2 is an exploded perspective view schematically illustrating a display device according to one or more embodiments of the present disclosure.

[0028] Figure 3 is a view schematically illustrating a display unit and an optical system according to one or more embodiments of the present disclosure.

[0029] Figure 4 、 Figure 5 、 Figure 6 and Figure 7 is a diagram illustrating incident light and output light polarization degrees and a light advancing path according to operation of a polarization light changing element in an optical system according to one or more embodiments of the present disclosure.

[0030] Figure 8 is a view schematically illustrating a display unit and an optical system according to one or more embodiments of the present disclosure.

[0031] Figure 9 、 Figure 10 、 Figure 11 and Figure 12 is a diagram illustrating incident light and output light polarization degrees and a light advancing path according to operation of a polarization light changing element in an optical system according to one or more embodiments of the present disclosure. DETAILED DESCRIPTION

[0032] By referring to the detailed description and drawings of the embodiments, it is easier to understand the aspects of some embodiments of the present disclosure and the methods for implementing them. The described embodiments are provided as examples so that the present disclosure will be thorough and complete and will fully convey the aspects of the present disclosure to those skilled in the art. Therefore, processes, elements and techniques that are redundant, irrelevant or unrelated to the description of the embodiments, or are not necessary for those of ordinary skill in the art to fully understand the aspects of the present disclosure may be omitted. Unless otherwise stated, throughout the drawings and written descriptions, the same reference numerals, symbols or combinations thereof represent the same elements, and therefore, their repeated descriptions may be omitted.

[0033] The described embodiments may have various modifications and may be implemented in different forms and should not be construed as limited to the embodiments shown herein. When describing embodiments, the use of "may," "could," or "may not" corresponds to one or more embodiments of the present disclosure.

[0034] It will be understood by those skilled in the art that, unless otherwise stated or implied, in view of the overall disclosure, the present disclosure covers all modifications, equivalents and substitutes within the conceptual and technical scope of the present disclosure, each of the features of the embodiments of the present disclosure may be combined with each other in part or in whole, and various interlocking and operations are technically feasible, and each embodiment may be implemented independently of each other, or may be implemented together in association.

[0035] In the accompanying drawings, the relative sizes of elements, layers, and regions may be exaggerated for clarity and / or descriptive purposes. In other words, because the sizes and thicknesses of the elements in the drawings are arbitrarily shown for ease of description, the disclosure is not limited thereto. In addition, the use of cross-hatching and / or shading is generally provided in the drawings to make the boundaries between adjacent elements clear. As such, unless otherwise indicated, the presence or absence of cross-hatching or shading does not convey or indicate any preference or requirement for the specific materials, material properties, dimensions, proportions, commonalities between the illustrated elements, and / or any other characteristics, attributes, properties, etc. of the elements.

[0036] It will be understood that when an element, layer, region, or component is referred to as being “formed on,” “on,” “connected to,” or “(operably or communicatively) coupled to” another element, layer, region, or component, the element, layer, region, or component may be directly formed on, directly on, directly connected to, or directly coupled to the other element, layer, region, or component, or indirectly formed on, indirectly on, indirectly connected to, or indirectly coupled to the other element, layer, region, or component, such that one or more intervening elements, layers, regions, or components may be present. Additionally, this may be collectively referred to as being directly or indirectly coupled or connected, and integrally or non-integrally coupled or connected. For example, when a layer, region, or component is referred to as being "electrically connected" or "electrically coupled" to another layer, region, or component, it may be directly electrically connected or coupled to the other layer, region, and / or component, or one or more intervening layers, regions, or components may be present. The one or more intervening components may include switches, resistors, and / or capacitors, etc. In describing embodiments, unless explicitly described as being directly connected, statements about connection refer to electrical connection, and "directly connected / directly coupled" or "directly on" means that one component is directly connected or coupled to another component or is directly on another component without intervening components.

[0037] In addition, in this specification, when a part of a layer, film, region, plate, etc. is formed on another part, the formation direction is not limited to the upward direction, but includes forming the part on the side surface or in the downward direction. On the contrary, when a part of a layer, film, region, plate, etc. is formed "under" another part, this includes not only the case where the part is "directly under" the other part, but also the case where there is another part between the part and the other part. On the other hand, other expressions describing the relationship between components, such as "between...", "immediately between..." or "adjacent to..." and "directly adjacent to..." can be interpreted similarly. It will be understood that when an element or layer is referred to as "between" two elements or layers, it can be the only element or layer between the two elements or layers, or one or more intervening elements or layers may also be present.

[0038] For purposes of this disclosure, expressions such as “at least one of” or “any of” or “one or more of” when following a list of elements modify the entire list of elements and do not modify the individual elements of the list. For example, “at least one of X, Y, and Z” and “at least one selected from the group consisting of X, Y, and Z” may be interpreted as X only, Y only, Z only, or any combination of two or more of X, Y, and Z (such as, for example, XYZ, XYY, YZ, and ZZ, or any variations thereof). Similarly, the expression “at least one of A and B” may include A, B, or A and B. As used herein, “or” generally means “and / or,” and the term “and / or” includes any and all combinations of one or more of the associated listed items. For example, the expression “A and / or B” may include A, B, or A and B. Similarly, expressions such as “at least one of,” “a plurality of,” “one of,” and other prepositional phrases when preceding (preceding) a list of elements modify the entire list and do not modify the individual elements of the list. When “C to D” is stated, this means C or greater and D or less, unless otherwise specified.

[0039] It will be understood that although the terms "first," "second," "third," etc. may be used herein to describe various elements, components, regions, layers, and / or parts, these elements, components, regions, layers, and / or parts should not be limited by these terms. These terms do not correspond to a specific order, position, or priority, and are merely used to distinguish one element, component, component, region, area, layer, part, or component from another element, component, component, region, area, layer, part, or component. Therefore, without departing from the spirit and scope of this disclosure, the first element, first component, first region, first layer, or first part described below may be referred to as the second element, second component, second region, second layer, or second part. Describing an element as "first" may not require or imply the presence of a second or other element. The terms "first," "second," etc. may also be used herein to distinguish elements of different categories or groups. For the sake of brevity, the terms "first," "second," etc. may respectively refer to "first category (or first group)," "second category (or second group)," etc.

[0040] The terms used herein are only used for the purpose of describing the embodiments and are not intended to limit the present disclosure. As used herein, unless the context clearly indicates otherwise, the singular forms "a" and "an" are also intended to include the plural forms, and the plural forms are also intended to include the singular forms. It will also be understood that when the terms "comprises," "having," "comprising," and variations thereof are used in this specification, it indicates the presence of the stated features, wholes, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or groups thereof.

[0041] As used herein, the terms “substantially,” “approximately,” “approximately,” and similar terms are used as approximate terms rather than as terms of degree, and are intended to account for inherent deviations in measured or calculated values ​​that one of ordinary skill in the art would recognize. For example, “substantially” may include a range of + / - 5% of the corresponding value. As used herein, “approximately” or “approximately” include the stated value and mean: within an acceptable range of deviations of the particular value as determined by one of ordinary skill in the art, taking into account the measurement in question and the errors associated with the measurement of the particular quantity (i.e., the limitations of the measurement system). For example, “approximately” may mean within one or more standard deviations, or within ±30%, ±20%, ±10%, ±5% of the stated value. In addition, the use of “may” when describing embodiments of the present disclosure refers to “one or more embodiments of the present disclosure.”

[0042] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure belongs. It will also be understood that terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and / or in this specification, and should not be interpreted in an idealized or overly formal sense unless so explicitly defined herein.

[0043] Figure 1 is a perspective view schematically illustrating a display device according to one or more embodiments of the present disclosure. Figure 2 is an exploded perspective view schematically illustrating a display device according to one or more embodiments of the present disclosure.

[0044] Reference Figure 1 and Figure 2 , the display device 1 may include a head-mounted display device that is mounted on the user's head to provide the user with a screen on which pictures or images are displayed.

[0045] The display device 1 may include a see-through type that can provide augmented reality based on actual external objects and / or a see-closed type that provides virtual reality to the user using a screen independent of external objects. Hereinafter, a see-closed type head-mounted display device will be described as an example, but the present disclosure is not limited thereto.

[0046] Reference Figure 1 and Figure 2 The display device 1 may include a display unit 10 , an optical system 20 , a housing portion 30 , a fixing portion 40 , and a buffer portion 50 .

[0047] In one or more embodiments, the display unit 10 may display or provide an image.The display unit 10 may emit light to display or provide a picture or image.

[0048] The display unit 10 can be housed in the housing portion 30. The display unit 10 can be configured to be opaque, transparent, or translucent, depending on the type of display device 1. The display unit 10 may include a display panel for displaying pictures or images. The display unit 10 may include a light-emitting display panel including light-emitting elements. For example, the display unit 10 may include an organic light-emitting display panel using organic light-emitting diodes including an organic light-emitting layer, a micro light-emitting diode display panel using micro light-emitting diodes (LEDs), a quantum dot light-emitting display panel using quantum dot LEDs including a quantum dot light-emitting layer, or an inorganic light-emitting display panel using inorganic light-emitting elements including inorganic semiconductors.

[0049] In one or more embodiments, the display unit 10 may include a first display unit 10a and a second display unit 10b. The first display unit 10a may correspond to the user's left eye, and the second display unit 10b may correspond to the user's right eye.

[0050] In one or more embodiments, the display unit 10 may include a first surface (or front surface) on which an image is displayed and a second surface (or rear surface) opposite to the first surface.

[0051] In one or more embodiments, the optical system 20 may allow light emitted from the display unit 10 to pass therethrough. The optical system 20 may refract and / or reflect the light emitted from the display unit 10. The optical system 20 may face the display unit 10. When a user wears the display device 1, the optical system 20 may be located between the user and the display unit 10. Therefore, the user can recognize light emitted from the display unit 10 and refracted and / or reflected by the optical system 20.

[0052] In one or more embodiments, the optical system 20 may include a first optical system 20a and a second optical system 20b. The first optical system 20a may correspond to the user's left eye and may overlap with the first display unit 10a. The second optical system 20b may correspond to the user's right eye and may overlap with the second display unit 10b.

[0053] In one or more embodiments, the housing portion 30 may house the display unit 10 and the optical system 20 therein. The housing portion 30 may have a space therein, and the display unit 10 and the optical system 20 may be located in the space. The housing portion 30 may protect the display unit 10 and the optical system 20 from external impact.

[0054] In one or more embodiments, the housing portion 30 may include a cover portion 31 and a main body portion 33. The housing portion 30 may be separated into the cover portion 31 and the main body portion 33. However, the present disclosure is not limited thereto, and the cover portion 31 and the main body portion 33 may be integrally formed. In one or more embodiments, the cover portion 31 may be located on the rear surface of the display unit 10, and the main body portion 33 may be located on the front surface of the display unit 10.

[0055] The fixing portion 40 can fix or mount the housing portion 30 on the user's head. The length of the fixing portion 40 can be adjusted according to the circumference of the user's head. The fixing portion 40 can include a structure (such as a strap or band) connected to the housing portion 30. The fixing portion 40 can be detachable from the housing portion 30.

[0056] In one or more embodiments, the cushioning portion 50 can improve the wearing comfort of the user. When the user wears the display device 1, the cushioning portion 50 can be located between the user and the housing portion 30. For example, the cushioning portion 50 can be attached to the housing portion 30. For example, the cushioning portion 50 can be detachable from the housing portion 30 and can be omitted from the display device 1.

[0057] In one or more embodiments, the display device 1 may further include a control unit. The control unit may perform operations such as calculating the user's pupil position, calculating the user's gaze direction, image processing (or image mapping) based on the calculated user's pupil position (or calculated user's gaze direction), and displaying the processed image on the display unit 10. The control unit may be implemented as a dedicated processor including an embedded processor and / or a general-purpose processor including a central processing unit, an application processor, etc. However, the present disclosure is not limited thereto.

[0058] Figure 3 is a view schematically illustrating a display unit and an optical system according to one or more embodiments of the present disclosure.

[0059] Reference Figure 1 、 Figure 2 and Figure 3 , the optical system 20 may be located between the display unit 10 and the user's pupil EYE. For example, the optical system 20 may be located between the first surface of the display unit 10 on which the image is displayed and the user's pupil EYE.

[0060] The optical system 20 may include polarization light changing elements LP, HWP1, and QWP, lens portions HM, LS, and CPR, and a geometric phase lens GPL.

[0061] Polarization light changing elements LP, HWP1, and QWP may be located on a first surface of the display unit 10. The polarization light changing elements LP, HWP1, and QWP may include a linear polarizer LP, a first half-wave plate HWP1, and / or a quarter-wave plate QWP.

[0062] The linear polarizer LP may be positioned on the first surface of the display unit 10. The linear polarizer LP may be directly positioned on the first surface of the display unit 10. The linear polarizer LP may polarize light emitted from the display unit 10 in a non-polarized light state in a corresponding direction.

[0063] The first half-wave plate HWP1 may be located on the linear polarizer LP. The first half-wave plate HWP1 may be located directly on the linear polarizer LP. The first half-wave plate HWP1 may be located between the linear polarizer LP and the quarter-wave plate QWP.

[0064] The first half-wave plate HWP1 is a component that adjusts the polarization direction of light and can delay the phase of transmitted light by λ / 2. In one or more embodiments, the first half-wave plate HWP1 can be an electrically switchable liquid crystal element. For example, the first half-wave plate HWP1 can include a first substrate, a second substrate, and liquid crystal positioned between the first and second substrates. The direction of polarized light can be changed by electrodes applied to both ends of the first and second substrates. Therefore, the first half-wave plate HWP1 can be implemented as a selective switching module capable of changing the polarization characteristics of transmitted light. Due to the feasibility of high-speed electrical drive, the step-by-step zoom distance can be reduced, and it can be used to design optical systems that take into account the user's visual characteristics.

[0065] The quarter-wave plate QWP may be located on the first half-wave plate HWP1. The quarter-wave plate QWP may be located directly on the first half-wave plate HWP1. The quarter-wave plate QWP may delay the phase of the transmitted light by λ / 4. For example, the quarter-wave plate QWP is a component that changes linearly polarized light into circularly polarized light and changes circularly polarized light into linearly polarized light. Depending on the properties of the incident linearly polarized light, the incident linearly polarized light may be polarized into left-handed circularly polarized light LCP that travels while rotating to the left relative to the traveling direction (see Figure 4 ) and right-handed circularly polarized light RCP that travels while rotating to the right relative to the forward direction (see Figure 4 ).

[0066] The lens portions HM, LS, and CPR may be pancake lenses. The lens portions HM, LS, and CPR may be positioned above the polarization-shifting elements LP, HWP1, and QWP. The lens portions HM, LS, and CPR may be positioned directly above the polarization-shifting elements LP, HWP1, and QWP. The lens portions HM, LS, and CPR may be positioned between the polarization-shifting elements LP, HWP1, and QWP and the geometric phase lens GPL. For example, the lens portions HM, LS, and CPR may be positioned between the quarter-wave plate QWP and the geometric phase lens GPL.

[0067] The lens sections HM, LS, and CPR may include a half-mirror HM, a lens LS, and / or a reflector CPR. Since the reflector CPR is disposed in the lens sections HM, LS, and CPR, it is possible to form focal planes at different distances using the lens sections HM, LS, and CPR depending on the polarization state of light incident on the lens sections HM, LS, and CPR. The reflector CPR may be a circularly polarized reflector CPR. The half-mirror HM, the lens LS, and / or the circularly polarized reflector CPR may be sequentially disposed on the first surface of the display unit 10.

[0068] The half-mirror HM may be located on the quarter-wave plate QWP. The half-mirror HM may be located directly on the quarter-wave plate QWP. The half-mirror HM may partially reflect incident light. For example, only approximately half of the light incident on the half-mirror HM may pass through the half-mirror HM. The half-mirror HM may include a semi-transmissive material. The half-mirror HM may include a metal such as magnesium (Mg), silver (Ag), and / or aluminum (Al), but the present disclosure is not necessarily limited thereto. In one or more embodiments, the half-mirror HM may have a curvature, but the present disclosure is not necessarily limited thereto.

[0069] The lens LS may be located on the half mirror HM. The lens LS may be located directly on the half mirror HM. The lens LS may be located between the half mirror HM and the circular polarization dependent reflector CPR. The circular polarization dependent reflector CPR may be located on the lens LS.

[0070] The geometric phase lens GPL may be located on the lens portions HM, LS, and CPR. The geometric phase lens GPL may be located between the lens portions HM, LS, and CPR and the user's pupil EYE. For example, the geometric phase lens GPL may be located between the circular polarization dependent reflector CPR and the user's pupil EYE.

[0071] Because the geometric phase lens (GPL) changes the circular polarization state of incident light, it is possible to form focal planes at different distances using a single geometric phase lens. Furthermore, using the geometric phase lens (GPL) can reduce the thickness of a thick lens based on general refraction to approximately several microns, thereby reducing or minimizing the volume of the optical system 20 and reducing its weight.

[0072] In one or more embodiments, the optical system 20 may further include a second half-wave plate HWP2. The second half-wave plate HWP2 may be located on lens portions HM, LS, and CPR. For example, the second half-wave plate HWP2 may be located on the circular polarization dependent reflector CPR. The second half-wave plate HWP2 may be located between lens portions HM, LS, and CPR and the geometric phase lens GPL. For example, the second half-wave plate HWP2 may be located between the circular polarization dependent reflector CPR and the geometric phase lens GPL. The second half-wave plate HWP2 may be located directly on the circular polarization dependent reflector CPR, and the geometric phase lens GPL may be located directly on the second half-wave plate HWP2.

[0073] The second half-wave plate HWP2 is a component that adjusts the polarization direction of light and can delay the phase of transmitted light by λ / 2. In one or more embodiments, the second half-wave plate HWP2 can be an electrically switchable liquid crystal element. For example, the second half-wave plate HWP2 can include a first substrate, a second substrate, and liquid crystal located between the first and second substrates, and the direction of polarized light can be changed by electrodes applied to the respective ends of the first and second substrates. Therefore, the second half-wave plate HWP2 can be implemented as a selective switching module capable of changing the polarization characteristics of transmitted light. Due to the feasibility of high-speed electrical drive, the step-by-step zoom distance can be reduced, and it can be used to design optical systems by considering the user's visual characteristics.

[0074] Figure 4 、 Figure 5 、 Figure 6 and Figure 7 is a diagram illustrating incident light and output light polarization degrees and a light advancing path according to operation of a polarization light changing element in an optical system according to one or more embodiments of the present disclosure.

[0075] Figure 4 It shows the polarization degrees of incident light and output light and the light advancing path of each element if the first half-wave plate HWP1 does not operate and the second half-wave plate HWP2 does not operate.

[0076] Reference Figure 4, the light output from the display unit 10 in a non-polarized light state can be changed into a linear polarization component of 45 degrees while passing through the linear polarizer LP rotated at 45 degrees. Because the 45-degree linear polarization is maintained due to the non-operation of the first half-wave plate HWP1, the light can be changed into left-handed circularly polarized light LCP when incident on the 90-degree quarter-wave plate QWP. After the light passes through the half-mirror HM, the polarization state of the light can be maintained in a left-handed circularly polarized light state while the light passes through the half-mirror HM and then passes through the circular polarization-dependent reflector CPR. Since the second half-wave plate HWP2 is non-operational, the light can be changed into right-handed circularly polarized light RCP while incident on the geometric phase lens GPL in a left-handed circularly polarized light state. Because the circular polarization state of the light incident on the geometric phase lens GPL is a left-handed circularly polarized light state, the corresponding lens can operate as a convex lens.

[0077] Figure 5 It shows the polarization degrees of incident light and output light and the light advancing path of each element if the first half-wave plate HWP1 does not operate and the second half-wave plate HWP2 operates.

[0078] Reference Figure 5 , the light output from the display unit 10 in a non-polarized light state can be changed to a 45-degree linear polarization component while passing through the linear polarizer LP rotated at 45 degrees. Because the 45-degree linear polarization is maintained due to the non-operation of the first half-wave plate HWP1, the light can be changed to left-handed circularly polarized light LCP when incident on the 90-degree quarter-wave plate QWP. After the light passes through the half-mirror HM, the polarization state of the light can be maintained in a left-handed circularly polarized light state while the light passes through the half-mirror HM and then passes through the circular polarization-dependent reflector CPR. Since the second half-wave plate HWP2 is operating, the polarization state of the light can be changed from a left-handed circularly polarized light state to a right-handed circularly polarized light state, and the light can be changed to a left-handed circularly polarized light LCP while incident on the geometric phase lens GPL in a right-handed circularly polarized light state. Because the circular polarization state of the light incident on the geometric phase lens GPL is a right-handed circularly polarized light state, the corresponding lens can operate as a concave lens.

[0079] Figure 6 Shown are the polarization degrees of incident light and output light and the light advancing path of each element if the first half-wave plate HWP1 operates and the second half-wave plate HWP2 does not operate.

[0080] Reference Figure 6, light output from the display unit 10 in a non-polarized light state can be changed into a 45-degree linear polarization component while passing through the linear polarizer LP rotated at 45 degrees. After the 45-degree linear polarization light is changed into -45-degree linear polarization light due to the operation of the first half-wave plate HWP1, the light can be changed into right-handed circularly polarized light RCP when incident on the 90-degree quarter-wave plate QWP. After the light passes through the half-mirror HM, when reflecting light in a right-handed circularly polarized light state, the light can be reflected by the circular polarization-dependent reflector CPR to be reflected again by the half-mirror HM. The light can be reflected by the half-mirror HM to pass through the circular polarization-dependent reflector CPR while being changed into left-handed circularly polarized light LCP. Since the second half-wave plate HWP2 is not working, the light can be incident on the geometric phase lens GPL in a left-handed circularly polarized light state and changed into right-handed circularly polarized light RCP. The circular polarization light state of the light incident on the geometric phase lens GPL is a left-handed circularly polarized light state, and the corresponding lens can operate as a convex lens.

[0081] Figure 7 Shown are the polarization degrees of incident light and output light and the light advancing paths of each element if the first half-wave plate HWP1 operates and the second half-wave plate HWP2 operates.

[0082] Reference Figure 7 , light output from the display unit 10 in a non-polarized light state can be changed into a linear polarization component of 45 degrees while passing through the linear polarizer LP rotated at 45 degrees. After the 45-degree linear polarization light is changed into -45-degree linear polarization light due to the operation of the first half-wave plate HWP1, the light can be changed into right-handed circularly polarized light RCP when incident on the 90-degree quarter-wave plate QWP. After the light passes through the half-mirror HM, when reflecting the light in the right-handed circularly polarized light state, the light can be reflected by the circular polarization-dependent reflector CPR to be reflected again by the half-mirror HM. The light can be reflected by the half-mirror HM to pass through the circular polarization-dependent reflector CPR while being changed into left-handed circularly polarized light LCP. When the second half-wave plate HWP2 is operating, the polarization state of the light can be changed from the left-handed circularly polarized light state to the right-handed circularly polarized light state, and the light can be incident on the geometric phase lens GPL in the right-handed circularly polarized light state to be changed into left-handed circularly polarized light LCP. Since the circularly polarized light state of the light incident on the geometric phase lens GPL is right-handed circularly polarized light state, the corresponding lens can work as a concave lens.

[0083] The optical system 20 can generate two focal lengths in the lens parts HM, LS and CPR itself by controlling the polarized light incident on the circular polarization dependent reflector CPR according to the above method, and can adjust the 2 focal lengths according to the number n of geometric phase lenses GPL. n+1The optical system is configured with a polarization-modulating element, a pancake lens, and a geometric phase lens, which reduces or minimizes the number of components within the optical system, thereby reducing the volume and weight of the optical system. Consequently, user fatigue can be reduced or minimized.

[0084] Hereinafter, one or more other embodiments will be described. Components identical to those already described are denoted by the same reference numerals, and repeated descriptions will be omitted or simplified.

[0085] Figure 8 is a view schematically illustrating a display unit and an optical system according to one or more embodiments of the present disclosure.

[0086] Reference Figure 8 , the optical system 20 ′ may be located between the display unit 10 and the user's pupil EYE. For example, the optical system 20 ′ may be located between the first surface of the display unit 10 on which the image is displayed and the user's pupil EYE.

[0087] The optical system 20 ′ may include polarization light changing elements LP, HWP1 , and QWP1 , lens portions HM, LS, QWP2 , and LPR, and a geometric phase lens GPL.

[0088] The polarization light changing elements LP, HWP1, and QWP1 may be located on the first surface of the display unit 10. The polarization light changing elements LP, HWP1, and QWP1 may include a linear polarizer LP, a first half-wave plate HWP1, and / or a first quarter-wave plate QWP1. Figure 3 The linear polarizer LP, the first half-wave plate HWP1 , and / or the first quarter-wave plate QWP1 are described in detail, and thus, descriptions of repeated portions will be omitted.

[0089] The lens portions HM, LS, QWP2, and LPR may be positioned above the polarization-shifting elements LP, HWP1, and QWP1. The lens portions HM, LS, QWP2, and LPR may be pancake lenses. The lens portions HM, LS, QWP2, and LPR may be positioned between the polarization-shifting elements LP, HWP1, and QWP1 and the geometric phase lens GPL. For example, the lens portions HM, LS, QWP2, and LPR may be positioned between the first quarter-wave plate QWP1 and the geometric phase lens GPL.

[0090] The lens portions HM, LS, QWP2, and LPR may include a half mirror HM, a lens LS, a second quarter wave plate QWP2, and / or a reflector LPR. The reflector LPR may be a linear polarization-dependent reflector LPR. The half mirror HM, the lens LS, the second quarter wave plate QWP2, and / or the linear polarization-dependent reflector LPR may be sequentially positioned on the first surface of the display unit 10.

[0091] The second quarter-wave plate QWP2 may be directly located on the lens LS, and the linear polarization-dependent reflector LPR may be directly located on the second quarter-wave plate QWP2. The second quarter-wave plate QWP2 may delay the phase of the transmitted light by λ / 4. For example, the second quarter-wave plate QWP2 is a component that changes linearly polarized light into circularly polarized light and changes circularly polarized light into linearly polarized light. Depending on the properties of the incident linearly polarized light, the incident linearly polarized light may be polarized into left-handed circularly polarized light LCP that travels while rotating to the left relative to the traveling direction (see Figure 9 ) and right-handed circularly polarized light RCP that travels while rotating to the right relative to the forward direction (see Figure 9 ).

[0092] The geometric phase lens GPL may be located on the lens portions HM, LS, QWP2, and LPR. The geometric phase lens GPL may be located between the lens portions HM, LS, QWP2, and LPR and the user's pupil EYE. For example, the geometric phase lens GPL may be located between the linear polarization dependent reflector LPR and the user's pupil EYE.

[0093] In one or more embodiments, the optical system 20' may further include a second half-wave plate HWP2. The second half-wave plate HWP2 may be located on the lens portions HM, LS, QWP2, and LPR. For example, the second half-wave plate HWP2 may be located on the linear polarization-dependent reflector LPR. The second half-wave plate HWP2 may be located between the lens portions HM, LS, QWP2, and LPR and the geometric phase lens GPL. For example, the second half-wave plate HWP2 may be located between the linear polarization-dependent reflector LPR and the geometric phase lens GPL.

[0094] In one or more embodiments, the optical system 20' may further include a third quarter wave plate QWP3. The third quarter wave plate QWP3 may be located between the second half wave plate HWP2 and the geometric phase lens GPL. The third quarter wave plate QWP3 may be located directly on the second half wave plate HWP2, and the geometric phase lens GPL may be located directly on the third quarter wave plate QWP3.

[0095] The third quarter-wave plate QWP3 can delay the phase of the transmitted light by λ / 4. For example, the third quarter-wave plate QWP3 is a component that changes linear polarized light into circular polarized light and changes circular polarized light into linear polarized light. According to the properties of the incident linear polarized light, the incident linear polarized light can be polarized into left-handed circularly polarized light LCP that advances while rotating to the left relative to the advancing direction (see Figure 9 ) and right-handed circularly polarized light RCP that travels while rotating to the right relative to the forward direction (see Figure 9 ).

[0096] Figure 9 、 Figure 10 、 Figure 11 and Figure 12 is a diagram illustrating incident light and output light polarization degrees and a light advancing path according to operation of a polarization light changing element in an optical system according to one or more embodiments of the present disclosure.

[0097] Figure 9 It shows the polarization degrees of incident light and output light and the light advancing path of each element if the first half-wave plate HWP1 does not operate and the second half-wave plate HWP2 does not operate.

[0098] Reference Figure 9 , light output from the display unit 10 in an unpolarized state can be changed to a 45-degree linear polarization component while passing through the linear polarizer LP rotated at 45 degrees. Because the 45-degree linear polarization is maintained due to the non-operation of the first half-wave plate HWP1, the light can be changed to left-handed circularly polarized light LCP while incident on the first quarter-wave plate QWP1 at 90 degrees. After the light passes through the half mirror HM, the polarization state of the light can be changed to a 45-degree linear polarization state while incident on the second quarter-wave plate QWP2 at 0 degrees. Thereafter, the polarization state of the light can be maintained in a 45-degree linear polarization state while passing through the linear polarization-dependent reflector LPR, which allows light in a 45-degree linear polarization state to be transmitted therethrough and allows light in a -45-degree linear polarization state to be reflected therefrom. Since the second half-wave plate HWP2 is not operating, light can be converted from 45-degree linearly polarized light to left-handed circularly polarized light (LCP) upon entering the 90-degree third quarter-wave plate QWP3. Then, it can be converted from 45-degree linearly polarized light to right-handed circularly polarized light (RCP) upon entering the geometric phase lens GPL. Because the circular polarization state of the light entering the geometric phase lens GPL is left-handed circularly polarized light, the corresponding lens can operate as a convex lens.

[0099] Figure 10 It shows the polarization degrees of incident light and output light and the light advancing path of each element if the first half-wave plate HWP1 does not operate and the second half-wave plate HWP2 operates.

[0100] Reference Figure 10 , light output from the display unit 10 in an unpolarized state can be changed to a 45-degree linear polarization component while passing through the linear polarizer LP rotated at 45 degrees. Because the 45-degree linear polarization is maintained due to the non-operation of the first half-wave plate HWP1, the light can be changed to left-handed circularly polarized light LCP while incident on the first quarter-wave plate QWP1 at 90 degrees. After the light passes through the half mirror HM, the polarization state of the light can be changed to a 45-degree linear polarization state while incident on the second quarter-wave plate QWP2 at 0 degrees. Thereafter, the polarization state of the light can be maintained in a 45-degree linear polarization state while passing through the linear polarization-dependent reflector LPR, which allows light in a 45-degree linear polarization state to be transmitted therethrough and allows light in a -45-degree linear polarization state to be reflected therefrom. Due to the operation of the second half-wave plate HWP2, light can be converted from -45-degree linearly polarized light to right-handed circularly polarized light (RCP) when incident on the third quarter-wave plate QWP3 (90-degree). Then, when incident on the geometric phase lens GPL, it is converted to left-handed circularly polarized light (LCP). Because the circular polarization state of the light incident on the geometric phase lens GPL is right-handed circularly polarized light, the corresponding lens can operate as a concave lens.

[0101] Figure 11 Shown are the polarization degrees of incident light and output light and the light advancing path of each element if the first half-wave plate HWP1 operates and the second half-wave plate HWP2 does not operate.

[0102] Reference Figure 11Light output from the display unit 10 in an unpolarized state can be changed to a 45-degree linear polarization component while passing through the linear polarizer LP, which is rotated at 45 degrees. Because the light is changed to -45-degree linear polarization by the operation of the first half-wave plate HWP1, the light can be changed to right-handed circularly polarized light (RCP) while incident on the first quarter-wave plate QWP1 at 90 degrees. After passing through the half mirror HM, the light's polarization state can be changed to a -45-degree linear polarization state while incident on the second quarter-wave plate QWP2 at 0 degrees. Thereafter, the light can be reflected by the linear polarization-dependent reflector LPR (which allows light in a 45-degree linear polarization state to transmit therethrough and allows light in a -45-degree linear polarization state to reflect therefrom), causing the -45-degree linear polarization component to be changed to right-handed circularly polarized light (RCP) while incident on the second quarter-wave plate QWP2 at 0 degrees. It can then be reflected by the half mirror HM to be changed to left-handed circularly polarized light (LCP). After that, the light can be incident on the second quarter-wave plate QWP2 at 0 degrees and converted to a 45-degree linearly polarized light component, thereby passing through the linear polarization-dependent reflector LPR. Since the second half-wave plate HWP2 is not in operation, the light can be incident on the third quarter-wave plate QWP3 at 90 degrees while in a 45-degree linear polarization state and converted to left-handed circularly polarized light LCP. Then, it can be incident on the geometric phase lens GPL and converted to right-handed circularly polarized light RCP. Because the circular polarization state of the light incident on the geometric phase lens GPL is left-handed circularly polarized, the corresponding lens can operate as a convex lens.

[0103] Figure 12 Shown are the polarization degrees of incident light and output light and the light advancing paths of each element if the first half-wave plate HWP1 operates and the second half-wave plate HWP2 operates.

[0104] Reference Figure 12Light output from the display unit 10 in an unpolarized state can be changed to a 45-degree linear polarization component while passing through the linear polarizer LP, which is rotated at 45 degrees. Because the light is changed to -45-degree linear polarization by the operation of the first half-wave plate HWP1, the light can be changed to right-handed circularly polarized light (RCP) while incident on the first quarter-wave plate QWP1 at 90 degrees. After passing through the half mirror HM, the light's polarization state can be changed to a -45-degree linear polarization state while incident on the second quarter-wave plate QWP2 at 0 degrees. Thereafter, the light can be reflected by the linear polarization-dependent reflector LPR (which allows light in a 45-degree linear polarization state to transmit therethrough and allows light in a -45-degree linear polarization state to reflect therefrom), causing the -45-degree linear polarization component to be changed to right-handed circularly polarized light (RCP) while incident on the second quarter-wave plate QWP2 at 0 degrees. It can then be reflected by the half mirror HM to be changed to left-handed circularly polarized light (LCP). After that, the light can be incident on the second quarter-wave plate QWP2 at 0 degrees and converted to a 45-degree linearly polarized light component, thereby passing through the linear polarization-dependent reflector LPR. Due to the operation of the second half-wave plate HWP2, the light can be converted to right-handed circularly polarized light RCP while incident on the third quarter-wave plate QWP3 at 90 degrees in a linearly polarized state of -45 degrees, and then converted to left-handed circularly polarized light LCP while incident on the geometric phase lens GPL. Because the circular polarization state of the light incident on the geometric phase lens GPL is right-handed circularly polarized, the corresponding lens can operate as a concave lens.

[0105] The optical system 20' can generate two focal lengths in the lens parts HM, LS, QWP2 and LPR itself by controlling the polarized light incident on the linear polarization dependent reflector LPR according to the above method, and can adjust 2 according to the number n of geometric phase lenses GPL. n+1 The distances between different focal planes are also reduced. Furthermore, the optical system is configured with a polarization-modulating element, a pancake lens, and a geometric phase lens, making it possible to reduce or minimize the number of components within the optical system, thereby reducing the volume and weight of the optical system. Consequently, the corresponding fatigue of the user can be reduced or minimized, similar to the above description.

[0106] According to the present disclosure, the polarization state of the optical system is controlled to adjust the n+1 (n is the number of geometric phase lenses) distances between different focal planes. Furthermore, the optical system, configured with a polarization-altering element, a pancake lens, and a geometric phase lens, reduces or minimizes the number of components within the optical system, thereby reducing the volume and weight of the optical system. Consequently, user fatigue can be reduced or minimized.

[0107] Embodiments have been disclosed herein, and although specific terms are employed, they are used and to be interpreted in a generic and descriptive sense only and not for purposes of limitation. In some cases, as will be apparent to one of ordinary skill in the art at the time of filing this application, features, characteristics, and / or elements described in connection with any particular embodiment may be used alone or in combination with features, characteristics, and / or elements described in connection with other embodiments, unless otherwise specifically indicated. Accordingly, those skilled in the art will understand that various changes in form and details may be made without departing from the spirit and scope of the present disclosure as set forth in the claims (functional equivalents thereof being included therein).

Claims

1. A display device, comprising: a display unit including a first surface on which an image is displayed and a second surface opposite to the first surface; Geometric phase lens; a polarization changing element, located between the first surface of the display unit and the geometric phase lens; as well as The lens portion is located between the polarization changing element and the geometric phase lens and includes a half mirror, a lens, and a reflector.

2. The display device according to claim 1, wherein The half mirror, the lens, and the reflector are sequentially arranged.

3. The display device according to claim 1, wherein The polarization light changing element includes a linear polarizer, a first half-wave plate, and a first quarter-wave plate.

4. The display device according to claim 3, wherein The first half-wave plate is located between the linear polarizer and the first quarter-wave plate.

5. The display device according to claim 3, wherein The reflector comprises a linear polarization dependent reflector. The display device according to claim 5 , wherein: The lens portion also includes a second quarter-wave plate positioned between the lens and the linear polarization dependent reflector. 7 . The display device according to claim 5 , further comprising a third quarter-wave plate located between the linear polarization-dependent reflector and the geometric phase lens.

8. The display device according to claim 3, wherein: The reflector comprises a circular polarization dependent reflector. 9 . The display device according to claim 1 , further comprising a second half-wave plate located between the lens portion and the geometric phase lens.

Images