KR20190108420A - Module of diffractive light guide plate - Google Patents

Abstract

Embodiments of the present invention provide a diffraction light guide plate, including: a diffraction light guide plate providing a light guide portion for guiding light, and a plurality of diffraction optical elements disposed on a surface of the light guide portion; and a reduction layer disposed on one aspect side of the light guide portion corresponding to an area in which at least one diffraction optical element among the plurality of diffraction optical elements is located, to reduce the ratio of reaching to a reference position spaced apart from one surface of the light guide portion toward the other surface side through the light guide portion.

Description

Diffraction Light Guide Plate Module {MODULE OF DIFFRACTIVE LIGHT GUIDE PLATE}

The present invention relates to a diffractive light guide plate module.

Recently, with the growing interest in display units that implement Augmented Reality (AR), Mixed Reality (MR), or Virtual Reality (VR), research on display units that implement them has been actively conducted. There is a trend. Display units that implement augmented reality, mixed reality, or virtual reality include a diffractive light guide plate module that uses diffraction based on wave nature of light.

The diffraction light guide plate module may include a light guide part and a diffraction light guide plate provided on one side or the other side of the light guide part and having a plurality of diffraction optical elements having a plurality of grating lines patterns. The diffractive light guide plate may be provided in plural according to the wavelength of the split light to be separated from the light incident through the light source.

1 is a schematic diagram of a diffraction light guide plate.

The diffraction light guide plate 10 is input through the input diffraction optical element 12 and the light guide part 11 to guide the light output through the micro light source output element L to be guided on the light guide part 11. Optically coupled with the diffractive optical element 12, the intermediate to allow a one-dimensional extension of the light received from the input diffractive optical element 12 in the first direction (y-axis direction in Fig. 1) by diffraction. Optically coupled with the intermediate diffraction optical element 13 through the diffraction optical element 13 and the light guide portion 11 and receiving light received from the intermediate diffraction optical element 13 by diffraction in a second direction (see FIG. 1). The output diffraction optical element 14 may be provided to be outputted from the light guide unit 11 and directed toward the user's pupil while the one-dimensional extension to the x-axis direction is made.

Figure 2 is a vertical direction perpendicular to the diffracted light guide plate showing the degree of the third diffractive optical emission angle (θ _e) that the device is emitted in a placement area according to the angle of incidence (θ _i) of the external light (O) other than the micro light source output device is varied It is a cross section.

3 is a graph showing the relationship between the diffraction angle θ _d and the emission angle θ _e in the region where the third diffractive optical element is disposed according to the incident angle θ _i of the external light O.

2 and 3 show that the refractive index of the diffractive light guide plate is 1.7, the period of the grating pattern of the third diffractive optical element is 400 nm, and the wavelength of incident external light O is 530 nm.

2 and 3, the external light O incident at the incident angle θ _i of −24 ° or less with respect to the surface of the light guide part 11 is not diffracted by the third diffractive optical element 14. (see (a) in Fig. 3), - the angle of incidence of external light (O) incident on the (θ _i) between 18 to 24˚ ˚ is diffracted and proceeds total reflection within the light guide portion 11 (FIG. 2 ( I a) and (a) and 3 (b) reference), ultraviolet light (O) incident on the incident angle (θ _i) between 18 ˚ to 90 ˚ is diffracted light guide portion 11 and then changes the traveling direction Is emitted through the light guide unit 11 without being totally reflected (see FIGS. 2B to 2G and FIGS. 3A and 3B).

On the other hand, the light emitted through the light guide portion 11 in the region where the third diffractive optical element 14 is disposed is less likely to reach the user's pupil as the emission angle θ _e is closer to 90 °, and 0 The closer to ˚, the higher the probability of reaching the user's pupil. When the external light (O) incident on the diffraction light guide plate 10 is emitted to reach the user's pupil, an image of a rainbow pattern is formed instead of a normal image by causing interference to image light that is input and expanded by a micro light source output element. There is a problem that can cause distortion.

The background art described above is technical information possessed by the inventors for the derivation of the embodiments of the present invention or acquired in the derivation process, and may be referred to as a publicly known technology disclosed to the general public before the application of the embodiments of the present invention. none.

KR 2016/0091402 A

The present invention is to provide a diffraction light guide plate module that can prevent the external light incident on the diffraction light guide plate from being unintentionally emitted to reach the pupil of the user.

Embodiments of the present invention include: a diffraction light guide plate including a light guide portion for guiding light and a plurality of diffractive optical elements disposed on a surface of the light guide portion; And external light of a reference wavelength band disposed in a region on one side of the light guide portion corresponding to a region where at least one diffractive optical element is located among the plurality of diffractive optical elements and incident at an angle of a predetermined reference range. And it provides a diffraction light guide plate module including a reduction layer for reducing the ratio of reaching to a reference position spaced apart from one surface of the light guide portion toward the other surface side through the light guide portion.

In the present embodiment, the plurality of diffractive optical elements include an input diffraction optical element for receiving light from a light source and diffracting the received light so that the received light can be guided on the light guide portion, and the input diffraction optical element An intermediate diffraction optical element configured to receive light diffracted therefrom and to be able to be expanded in one dimension by diffraction, and to receive light extended from the intermediate diffraction optical element and to receive the light by diffraction An output diffraction optical element configured to be output from an optical guide, wherein the reduction layer may be disposed on at least an output diffraction optical element side of the input diffraction optical element, the intermediate diffraction optical element, and the output diffraction optical element.

In the present embodiment, the diffractive optical element in which the reduction layer is disposed is disposed on one surface of the light guide portion with a grating line pattern having a period d, and the reference position of the diffraction optical element in which the reduction layer is disposed. Spaced apart from the lower side of the diffractive optical element by a length B in a first direction from a lower side to an upper side, and spaced apart from the one side by a length R in a second direction perpendicular to the first direction from the one side of the optical guide and toward the other side. The reduced layer preferably reduces the rate at which the external light incident to the reference position reaches the reference position at an angle equal to or greater than the reference incident angle determined by the following [Condition 1]:

[Condition 1]

Where θ Is the reference incidence angle, λ is the minimum wavelength of the reference wavelength band, is the period of the grating pattern of the diffractive optical element on which the reduction layer is disposed, and B is between the lower side of the diffractive optical element on which the reduction layer is disposed and the reference position. The first reference shortest distance, R is the second reference shortest distance between one surface of the light guide portion and the reference position.

In the present embodiment, the reference wavelength band may be 400 nm to 700 nm.

In the present embodiment, the diffraction light guide module includes a first diffractive optical element for separating light of wavelengths of 550 nm or more and 700 nm or less, a second diffractive optical element for separating light of wavelengths of 400 nm or more and 550 nm or less and 450 nm or more A plurality of diffraction light guide plates including at least one of the third diffractive optical elements that separate light having a wavelength of 650 nm or less are stacked, and the reference incident angle is an output diffraction including the d in [Condition 1] in the plurality of diffraction light guide plates. It may be determined based on the case where the longest period among the grid pattern periods of the optical elements is selected.

In the present embodiment, the reducing layer is a film that is formed to be elongated along a direction parallel to the first direction, and includes a light transmitting part and a light blocking part that are arranged to cross each other along a direction parallel to the first direction. Louver film.

In this embodiment, the micro louver film, the thickness and the length of the light transmitting portion preferably satisfy the following [Condition Formula 2]:

[Condition Formula 2]

Here, a is the thickness of the micro louver film, b is the length of the light transmitting portion.

In this embodiment, the reduction layer is a first linear polarizer; And first and second non-linear spray-oriented liquid crystal films sequentially formed on the first linear polarizer.

In this embodiment, the tilt factor of the first or second non-linear spray oriented liquid crystal film may be less than 0.95 or greater than 1.05.

In the present embodiment, the optical film may further include a second linear polarizer disposed adjacent to the second non-linear spray-oriented liquid crystal film.

In this embodiment, the reduction layer is a first linear polarizer; And an optical film including first and second liquid crystal films sequentially formed on the first linear polarizer and including a linear spray-oriented liquid crystal compound.

In the present embodiment, the optical film may further include a second linear polarizer disposed adjacent to the second liquid crystal film.

A diffraction light guide plate module according to an embodiment of the present invention is disposed in a region on one surface of an optical guide part corresponding to a region in which at least one diffractive optical element is located among a plurality of diffractive optical elements and incident at a predetermined reference range angle. Is provided with a reduction layer for reducing the rate at which the external light reaches the reference position spaced apart from one surface of the light guide portion toward the other surface side through the diffraction optical element and the optical guide portion, so that unintentional external light is incident on the extended image light. By interfering and emitting together, distortion of the extended video light such as a rainbow pattern can be prevented.

1 is a schematic diagram of a diffraction light guide plate.
FIG. 2 is a vertical cross-sectional view of a diffraction light guide plate showing a degree of change in an exit angle emitted from a region in which a third diffractive optical element is disposed according to an incident angle of external light other than the micro light source output element.
3 is a graph showing a relationship between a diffraction angle and an emission angle in a region in which a third diffractive optical element is disposed according to an incident angle of external light.
4 is a view schematically showing a part of a diffraction guide plate module according to an aspect of the present invention.
5 is a vertical cross-sectional side view of the diffractive optical element and the light guide portion in which a reduction layer is disposed for explaining a method of calculating an incident condition of external light that may reach a reference position.
FIG. 6 is a schematic diagram of one embodiment of a reduction layer in which a micro louver film is disposed on the diffractive optical element side.
7 is a schematic view of an optical film including a liquid crystal film as another embodiment of the reduction layer.
It is a schematic diagram for demonstrating spray orientation.

The invention will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the present embodiments are intended to complete the disclosure of the present invention, and the general knowledge in the art to which the present invention pertains. It is provided to fully convey the scope of the invention to those skilled in the art, and the present invention is defined only by the scope of the claims. Meanwhile, the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In this specification, the singular also includes the plural unless specifically stated otherwise in the phrase. As used herein, “comprises” and / or “comprising” refers to the presence of one or more other components, steps, operations and / or elements. Or does not exclude additions. Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are only used to distinguish one component from another.

In the present specification, the term "light guide part" may be defined as a structure for guiding light from the inside using total internal reflection. The condition for total internal reflection requires that the refractive index of the light guide portion is greater than that of the peripheral medium adjacent the surface of the light guide portion. The light guide portion may be formed including glass and / or plastic material, and may be transparent or translucent. The light guide part may be formed in various layouts in the plate type. Here, the term "plate" means a three-dimensional structure having a predetermined thickness between one surface and the other surface thereof, and one surface and the other surface may be a substantially flat plane, but at least one of the one surface and the other surface may be It may be formed to be curved in one or two dimensions. For example, the plate-type light guide portion may be curved in one dimension so that one surface and / or the other surface thereof has a shape corresponding to a part of the side surface of the cylinder. However, the curvature formed by the curvature preferably has a radius of curvature sufficiently large to facilitate total internal reflection to guide the light on the light guide portion.

In the present specification, the term "diffraction optical element" may be defined as a structure for changing the optical path by diffracting light on the light guide portion. Here, the "diffraction optical element" may mean a portion in which a plurality of grid lines oriented in one direction on the optical guide part are arranged in a predetermined direction to form a predetermined area while having a pattern.

In the present specification, the term “lattice line” is a projection shape (ie an embossed pattern) having a predetermined height on the light guide portion surface and / or a groove shape (ie an intaglio pattern having a predetermined depth on the light guide portion surface). May mean. Here, the alignment direction of the grating lines may be freely designed so that the optical path may be changed in the intended direction through diffraction by the diffractive optical element.

4 is a view schematically showing a part of a diffraction guide plate module according to an aspect of the present invention.

Referring to FIG. 4, the diffraction guide plate module 1000 may include a diffraction light guide plate 100 and a reduction layer 200. Although the reduction layer 200 is disposed adjacent to the diffraction light guide plate 100, it is illustrated in FIG. 4 in a form separated from the diffraction light guide plate 100 for convenience of description.

The diffractive light guide module includes a first diffractive optical element for separating and diffracting light having a wavelength of 550 nm or more and 700 nm or less, a second diffractive optical element for separating and diffracting light having a wavelength of 400 nm or more and 550 nm or less and a wavelength of 450 nm or more and 650 nm or less It may have a structure in which a plurality of diffraction light guide plates including at least one of the third diffractive optical elements that separate and diffract light having a wavelength are stacked. The diffractive light guide module is preferably a structure that can include all of the first diffraction optical element, the second diffraction optical element, and the third diffraction optical element by combining a plurality of diffraction light guide plates. For example, the diffraction light guide module may include a first diffraction light guide plate having a first diffraction optical element on one surface of the first optical guide part, and a second diffraction light guide plate having a second diffraction optical element on any one surface of the second optical guide part. And a third diffractive light guide plate including a third diffractive optical element on one surface of the third optical guide part. In another example, the diffraction light guide module includes a first diffraction light guide plate including a first diffraction optical element on one surface of the first optical guide part, and a second diffraction optical element on the other surface of the first optical guide part, and a second diffraction light guide plate. The second diffractive light guide plate including the third diffractive optical element may be stacked on one surface of the optical guide part. Hereinafter, the diffraction light guide module includes, for convenience of description, a first diffraction light guide plate having a first diffraction optical element, a second diffraction light guide plate having a second diffraction optical element, and a third diffraction light guide plate having a third diffraction optical element. It will be described based on the structure that is stacked on each other.

4 shows a diffraction light guide plate located farthest from the pupil side of the user in the diffraction light guide module, and the remaining diffraction light guide plates are not shown.

The diffraction light guide plate 100 may include an optical guide unit 110 and a plurality of diffractive optical elements 120, 130, and 140 disposed on the surface of the optical guide unit 110.

The light guide unit 110 may guide light from the inside by using total internal reflection.

The input diffraction optical element 120 may receive the light L1 from the light source S and diffract the received light so that the received light may be guided on the light guide unit 110.

The intermediate diffraction optical element 130 may be configured to receive light L2 diffracted from the input diffraction optical element 120 and to allow the received light to be expanded one-dimensionally by diffraction. The diffracted light received from the input diffraction optical element 120 passes through the intermediate diffraction optical element 130, and part of the diffraction light is diffracted to change the light path, and the rest of the diffracted light may be totally reflected by the existing optical path. Since the first received light can be divided into a plurality of beams L3 while the diffraction is made a plurality of times at a point spaced in a specific direction, a one-dimensional extension can be achieved.

The output diffraction optical element 140 may be configured to receive the light L3 extended from the intermediate diffraction optical element 130 and to receive the received light from the light guide unit 110 by diffraction. On the other hand, the output diffraction optical element 140 may also expand light received from the intermediate diffraction optical element 130 one-dimensionally by diffraction. In this case, the direction in which the plurality of beams L3 formed by the light extended by the intermediate diffraction optical element 130 are separated from the light receiving side 140a of the output diffraction optical element 140, and the single beam L3 is spaced apart from each other. Since the directions in which the plurality of beams L4 extended by the reference output diffractive optical element 140 are spaced apart from each other (for example, orthogonal to each other) cross each other, the input diffraction optical element 120 from the light source S eventually becomes Two-dimensional extension is made to the light reference.

The reduction layer 200 is disposed in a region corresponding to a region where at least one diffractive optical element of the plurality of diffractive optical elements 120, 130, and 140 is located on one surface 110a side of the light guide unit 110 in advance. Outside light O incident at a reference wavelength range at a predetermined reference range is spaced apart from one surface 110a of the optical guide unit 110 toward the other surface 110b through the diffractive optical element and the optical guide unit 110. The ratio reached to the reference position P can be reduced. The reduction layer 200 is preferably disposed on at least the output diffraction optical element 140 of the input diffraction optical element 120, the intermediate diffraction optical element 130, and the output diffraction optical element 140. Image light output from the light source (S) is diffracted by the plurality of diffractive optical elements (120, 130, 140) is guided through the light guide unit 110, and finally extended image light is output from the light guide unit 110 The output diffraction optical element 140 is an area where the output diffraction optical element 140 is located, and when an unintended external light is incident through the light guide unit 110 in addition to the extended image light, it causes interference to the extended image light, thereby causing a rainbow pattern. This can be caused.

5 is a vertical cross-sectional side view of the diffractive optical element and the light guide portion in which a reduction layer is disposed for explaining a method of calculating an incident condition of external light O that may reach the reference position P. FIG.

5A illustrates a critical angle θ of the horizontal line H of the optical path that can reach the reference position P through the region of the light guide part 110 occupied by the diffractive optical element 140 when there is no reduction layer. _e ) is a diagram showing.

Here, the diffractive optical element 140 may be disposed on one surface 110a of the light guide part 110 having a grid line pattern having a period d.

Here, the reference position P is spaced apart from the lower side 140b of the diffractive optical element 140 by the length B in the first direction D1 toward the upper side 140c from the lower side 140b of the diffractive optical element 140. The light guide part 110 may be positioned to be spaced apart from the one surface 110a by the length R in one surface 110a in a second direction perpendicular to the first direction D1 and toward the other surface 110b. The reference position P may be determined as a position corresponding to a point where the user's pupil may be positioned when manufacturing the display device including the diffractive light guide module.

Meanwhile, referring to FIG. 5, in the absence of the reducing layer, the reference angle H of the horizontal line H of the optical path that may reach the reference position P through the area of the light guide part 110 occupied by the diffractive optical element 140 ( θ _e ) may be defined by Equation 1 below.

[Equation 1]

Where θ _e Is the reference critical angle θ _e of the horizontal line H of the optical path that can reach the reference position P, B is the first reference reference shortest distance between the reference position and the lower side of the diffractive optical element on which the reducing layer is disposed, R May be defined as the shortest reference distance in the second direction between one surface of the light guide portion and the reference position. Here, it is assumed that the thickness t of the light guide part 110 is considerably thinner than R.

5 (b) shows that when there is no reduction layer, external light O is incident and diffracted by the diffractive optical element 130 and then emitted through the light guide part 110 to reach the reference position P. It is a figure which shows an example of an optical path.

Exit angle (θ _o) in a condition of the diffracted light diffracted by the diffractive optical element 130 can reach to a reference position (P) are shown in the condition of A.

Conditional Expression A

That is, the emission angle (θ _o) to less than the horizontal line (H) based on the critical angle (θ _e) of the optical path to reach the reference position (P), the diffracted light diffracted by the diffractive optical element 130 This reference position P is reached.

On the other hand, light having a wavelength of λ is incident on the diffraction optical element 140 having a refractive index of n and a period of the grating pattern is d at the incident angle θ on the horizontal line H, and is diffracted in the light guide part 110. the diffracted light and the diffraction horizon (H) is the angle (θ _d) is in the following equation (2) relationship.

[Equation 2]

In addition, the exit angle θ _o emitted through the light guide unit 110 outside the conditions that can be totally reflected in the light guide unit 110 is related to the diffraction angle θ _d , and Snell's law. It can be defined by the following equation (3).

[Equation 3]

Therefore, the incident angle θ Can be defined by the following equation (4) by a combination of equations (2) and (3).

[Equation 4]

On the other hand, by combining Equation 4 and condition A, the following condition B can be derived.

Conditional Expression B

클 때일 수 있다.That is, light having a wavelength λ is incident on the diffraction optical element 140 having a refractive index of n and a period of the grating pattern is d at the incident angle θ on the horizontal line H, and is emitted through the diffraction and light guide unit 110. The angle of incidence θ relative to the horizontal line (H) this

It can be big.

Therefore, it is preferable that the reduction layer 200 reduces the rate at which the external light incident to the reference position reaches the reference position at an angle equal to or greater than the reference incident angle determined by the following [Condition 1]. Here, the term “reduce” may mean lowering the transmittance of light incident at an angle greater than or equal to the reference incident angle compared to the transmittance of light incident at an angle smaller than the reference incident angle.

[Condition 1]

Where θ Is the reference incident angle, λ is the minimum wavelength in the reference wavelength band, is the period of the grating pattern of the diffractive optical element on which the reducing layer is disposed, B is the first direction reference between the lower side and the reference position of the diffractive optical element on which the reducing layer is disposed. The shortest distance, R, may be defined as the shortest reference distance in the second direction between one surface of the light guide portion and the reference position.

The reference wavelength band may be 400 nm to 700 nm, which is a wavelength band of the visible light region. In addition, the reference incident angle θ is preferably determined based on a case in which d in [Condition 1] is selected as the longest period among the lattice pattern periods of the output diffractive optical elements included in the plurality of diffractive light guide plates. When d in [Condition 1] is not selected as the longest period among the lattice pattern periods of the output diffraction optical elements included in the plurality of diffraction light guide plates, the reduction layer 200 is applied to a reference wavelength band that is incident at an angle equal to or greater than the reference incident angle. Although the transmittance of external light is designed to be below a predetermined reference, in the diffraction light guide plate on which the output diffraction optical element having the longest period lattice pattern is disposed, the transmittance of external light in the reference wavelength band incident at an angle equal to or greater than the reference incident angle is less than or equal to the predetermined reference. Because it may not be. That is, the external light transmittance of the reference wavelength band incident at an angle equal to or greater than the reference incident angle may not be lower than the predetermined criterion as the entire reference of the diffraction LGP module.

For example, the first wavelength between the reference position and the lower side of the diffraction optical element having the minimum wavelength lambda λ of 400 nm, the period of the lattice pattern of the diffraction optical element on which the reduction layer is disposed, and the period of the grating line pattern is set to 408 nm. When the reference reference shortest distance B is 10 mm and the second reference reference shortest distance R between one surface of the light guide portion and the reference position is 30 mm, the reference incident angle θ is substituted. Can be derived to about 41.6 degrees, and thus the reduction layer needs to reduce the transmittance of external light incident at an angle of 41.6 degrees or more.

6 is a schematic view of a micro louver film as an example of a reduction layer.

An embodiment of the reduction layer is a film that is elongated along a direction parallel to the first direction D1, and the light-transmitting portion 210a intersects with each other along a direction parallel to the first direction D1. It may include a micro louver film (200a) having a light portion (220a).

The light transmitting portion 210a has a length b in the first direction D1 longer than the length c of the light blocking portion 210b, so that the overall light transmittance of the micro louver film 200a is not significantly reduced. The length b of the light transmitting portion 210a is preferably 50 to 500 µm, more preferably 70 to 200 µm. The length c of the light shielding part 220a is 1-100 micrometers, Preferably it is 10-50 micrometers. The angle of the light shielding portion 220a is approximately 40 ° to 90 °. The angle of the light blocking portion 210b means an angle between the surface of the micro louver film 200a and the length direction of the light blocking portion 220a. In the present exemplary embodiment, the angle of the light blocking part 210b is 90 °.

The light transmitting portion 210a may preferably be made of a polymer having a high light transmittance. As such a polymer, a thermoplastic resin, a thermosetting resin, a resin curable with actinic rays such as UV rays, or the like may be used. Examples of such resins include cellulose resins (eg, cellulose acetate butyrate, triacetylcellulose, etc.), polyolefin resins (eg, polyethylene, polypropylene, etc.), polyester resins (eg, polyethylene terephthalate, etc.), polystyrene, polyurethane, Polyvinyl chloride, acrylic resins, polycarbonate resins, and the like.

The light blocking portion 220a may be formed through a light shielding material that absorbs or reflects light. Examples of such materials include (1) dark pigments or dyes, such as black or gray pigments or dyes, (2) metals such as aluminum, silver, (3) dark metal oxides, and (4) dark pigments Or the aforementioned polymers containing dyes.

The micro louver film 200a preferably has a thickness a and a length of the light transmitting part 210a satisfying the following [Condition 2].

[Condition Formula 2]

Here, a means the thickness of the micro louver film, and b means the length of the light transmitting part.

Hereinafter will be described the process in which [Condition 2] is derived.

The region through which the light is transmitted through the structure in which the micro louver film shown in FIG. 6 is disposed on the side of the diffractive optical element is a region where the light transmitting portion 210a is positioned, and the critical angle of incidence through which the light transmitting portion 210a is transmitted is possible. (θ _i ) is shown in Equation 3 below.

[Equation 3]

On the other hand, as described above, since the reduction layer 200 preferably reduces the rate at which the external light entering the reference wavelength band at an angle equal to or greater than the reference incidence angle determined by [Condition 1] reaches the reference position, ] And [Equation 3] in combination with the thickness (a) of the micro louver film 200a and the length (b) of the light-transmitting portion 210a may be derived as shown in [Condition 2].

In addition, the reference incident angle θ derived as an example The condition of the length b of the light transmitting portion 210a to the thickness a of the micro louver film 200a for reducing the transmittance of external light incident at an angle of about 41.6 ° or more is such that b / a is 0.66 or less. This is preferred.

7 is a schematic view of an optical film including a liquid crystal film as another embodiment of the reduction layer.

Another embodiment of the reduction layer includes a first linear polarizer 210b, a second linear polarizer 220b, and a liquid crystal film 230b disposed between the first linear polarizer 210b and the second linear polarizer 220b. It may be an optical film 200b.

As used herein, the term “polarizer” refers to a functional layer that exhibits selective transmission and blocking properties, such as reflection or absorption properties, for incident light. For example, the polarizer may have a function of transmitting light vibrating in one direction from incident light vibrating in various directions and blocking light vibrating in the other direction. As used herein, the term "linear polarizer" refers to a case where linearly polarized light that selectively transmits light vibrates in one direction and linearly polarized light that vibrates in a direction perpendicular to the vibration direction of the linearly polarized light. The kind of the linear polarizer is not particularly limited and, for example, as a reflective polarizer, for example, a dual brightness enhancement film (DBEF), a lyotropic liquid crystal (LLC layer) or a wire grid polarizer Or the like, and as an absorption type polarizer, for example, an anisotropic polarizer in which a polymer stretched film such as a PVA stretched film or the like is used as a host or a liquid crystal polymerized in an oriented state, and arranged according to the alignment of the liquid crystal. Guest-host type polarizers using dye as guest may be used, but are not limited thereto.

The absorption axes of the first linear polarizer 210b and the second linear polarizer 220b may be parallel to each other.

The liquid crystal film 230b may have a structure in which a difference in phase retardation occurs depending on an angle of propagation of light with respect to a surface thereof. As a result, the light incident through the second linear polarizer 220b passes through the liquid crystal film 230b in a linearly polarized state. The degree of phase retardation also varies according to the incident angle of the light, and the linearly polarized state of the transmitted light (specifically, Since the vibration direction of the linearly polarized light is also different, the transmittance may vary according to the vibration direction of the linearly polarized light reaching the first linearly polarized light 210b, so that transmission control according to the incident angle of the light incident through the second polarizer 220b becomes possible. .

One example of the liquid crystal film 230b may be the first and second non-linear spray-oriented liquid crystal films 231b and 232b sequentially formed on the first linear polarizer 210b.

Another example of the liquid crystal film 230b may include first and second liquid crystal films 233b and 234b sequentially formed on the first linear polarizer 210b and each including a linear spray-oriented liquid crystal compound. .

As used herein, the term “spray orientation” refers to an orientation state in which the tilt angle of the liquid crystal compound present in the liquid crystal film is gradually changed according to the thickness direction of the liquid crystal film. As used herein, the term “tilt angle” means the minimum angle formed between the optical axis of the liquid crystal compound and the surface of the liquid crystal film. As used herein, the term "average tilt angle" means a tilt angle when the average value of the tilt angles of the entire liquid crystal compounds or the arrangement of the entire liquid crystal compounds is converted into an average value. As used herein, the term “optical axis” refers to an axis in the direction of a long axis in the shape of a rod when the liquid crystal compound is in the shape of a rod, and an axis in the normal direction of the disc plane when the liquid crystal compound is in the shape of a disc. Therefore, in the present specification, "the liquid crystal film includes a liquid crystal compound spray-oriented" means that when the liquid crystal compound has a rod shape, the major axis direction gradually changes depending on the thickness direction of the liquid crystal film, or the liquid crystal compound is the original In the case of the shape, it means that the normal direction of the original plane is gradually changed according to the thickness direction of the liquid crystal film.

In one example, the spray orientation is, for example, in the range that the minimum tilt angle of the liquid crystal compound in the liquid crystal film is about 0 to 20 degrees, and the maximum tilt angle is about 70 to 90 degrees, the tilt angle is It may mean an alignment state that gradually changes depending on the thickness direction of the liquid crystal film.

Spray orientation can be divided into linear spray orientation and non-linear spray orientation. As used herein, the term “linear spray orientation” refers to an alignment state in which a graph shown with a linear graph is represented by a thickness of the liquid crystal film as an x axis and a local tilt angle corresponding to the thickness as a y axis. That is, it means an alignment state whose slope is constant. In one example, the linear spray orientation is based on the x-axis (i.e. x = 0 to 1.0) of the ratio z / d of the thickness z to the total thickness d of the liquid crystal film, corresponding to the thickness. The tilt angle of the graph shown on the x-axis is set so that the local tilt angle is the y-axis, and the interval (b) between the minimum and maximum tilt angles on the y-axis is equal to the interval (a) within the range of x = 0 to 1.0. Can therefore mean a constant orientation state, for example an orientation state in which the average tilt factor is in the range of about 0.95 to 1.05 (see graph A in FIG. 8).

In contrast, the term “non-linear spray orientation” herein refers to an alignment state in which the graph shown with the thickness of the liquid crystal film as the x axis and the local tilt angle corresponding to the thickness as the y axis shows the nonlinear graph. That is, it means an orientation state in which the slope thereof changes depending on the thickness of the liquid crystal film. In one example, the nonlinear spray orientation may refer to an alignment state in which the tilt angle of the tilt angle with respect to the thickness of the liquid crystal film is gradually increased or gradually decreased. In one example, the non-linear spray orientation is the x-axis (i.e. x = 0 to 1.0) of the corresponding thickness z to the total thickness d of the liquid crystal film, i. The tilt angle of the graph shown on the x-axis is set so that the local tilt angle is the y-axis, and the interval (b) between the minimum and maximum tilt angles on the y-axis is equal to the interval (a) within the range of x = 0 to 1.0. Gradually decrease along with an average tilt factor of less than about 0.95 (see graph B in FIG. 8) or gradually increasing along the x-axis, but with an average tilt factor of greater than about 1.05. (See graph C in FIG. 8).

In one specific example, the non-linear spray orientation gradually decreases along the x-axis in terms of effectively implementing selective transmission and blocking characteristics according to the viewing angle as described below, while the average tilt factor is Or less than about 0.95, for example, about 0.9 or less, about 0.8 or less, about 0.7 or less. In this case, the lower limit of the average slope may be about 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more or 0.6 or more.

As long as there is no particular mention of the tilt factor in the present specification, it may mean a tilt factor value derived by measuring the phase difference of the film for each angle using Axoscan (Axometrix Co., Ltd.). The tilt factor of the spray oriented liquid crystal film may be adjusted by adjusting the process temperature at the time of manufacturing the spray oriented liquid crystal film. In one example, the spray oriented liquid crystal film may be prepared by curing a layer of a known spray oriented liquid crystal composition. In the above curing may be carried out by irradiating the layer of the spray-aligned liquid crystal composition with ultraviolet rays, it is possible to adjust the tilt factor of the spray-oriented liquid crystal film by adjusting the temperature at the time of irradiation of the ultraviolet rays. For example, the tilt factor tends to increase as the temperature at the time of ultraviolet irradiation increases.

In the optical film, when the first and second liquid crystal films are nonlinear spray-oriented liquid crystal films, the optical film is advantageous in exhibiting selective transmission and blocking characteristics different in viewing angle. In this case, the average tilt angle of the first and / or second liquid crystal film may be, for example, within a range of 45 degrees to 55 degrees. When the first and second liquid crystal films each implement a non-linear spray orientation at the front surface, the first and second liquid crystal films may function as linear twisted nematic films at an inclination angle, which is advantageous in showing selective transmission characteristics according to the viewing angle. Therefore, when the average tilt angle of the first and / or second liquid crystal film is within the above range, it is advantageous to exhibit selective transmission characteristics according to the viewing angle.

Meanwhile, the first and second liquid crystal films 231b, 232b, 233b, and 234b are adjacent to the interface with the first linear polarizer 210b and / or the second linear polarizer 220b based on the condition 1 above. Tilt angle in the zone (the reference left and right of FIG. 7B) is 0 to 30 degrees, and the tilt in the zone (the center of reference of FIG. 7B) adjacent to the interface with both liquid crystal films 231b, 232b, 233b, and 234b. The angle is 60 to 90 degrees, the tilt factor is 0.7 to 1.3, the thickness of the liquid crystal film may be selectively determined and designed between 0.5 to 5 ㎛. As a result, the blocking layer 200b may be disposed on the diffractive optical element 140 side to reduce the rate at which external light reaches the reference position in the reference wavelength band incident at an angle equal to or greater than the reference incidence angle determined by [Condition 1].

The diffractive light guide plate module 1000 according to the exemplary embodiment of the present invention includes a light guide unit 110 corresponding to a region in which at least one diffractive optical element 140 is positioned among the plurality of diffractive optical elements 120, 130, and 140. Outside light of a reference wavelength band disposed in an area on one surface 110a and incident at an angle of a predetermined reference range is received from one surface 110a of the optical guide unit 110 through the diffractive optical element 140 and the optical guide unit 110. Since the reduction layer 200 for reducing the rate of reaching the reference position (P) spaced toward the other surface 110b side is provided, unintentional external light is incident and interferes with the extended image light and is emitted together, resulting in a rainbow. There is an advantage that can prevent distortion of the extended image light, such as pattern.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, it is possible to make various modifications or variations without departing from the spirit and scope of the invention. Accordingly, the appended claims will include such modifications and variations as long as they fall within the spirit of the invention.

100: diffraction light guide plate
110: light guide part
120: input diffraction optical element
131: main intermediate diffractive optical element
132: auxiliary intermediate diffractive optical element
140: output diffraction optical element
200: reduction layer

Claims (12)

A diffraction light guide plate including a light guide part for guiding light and a plurality of diffractive optical elements disposed on a surface of the light guide part; And
The diffraction optical element includes external light of a reference wavelength band disposed in a region on one side of the light guide portion corresponding to a region in which at least one diffraction optical element is located and incident at an angle of a predetermined reference range. And a reduction layer for reducing a rate of reaching the reference position spaced apart from one surface of the light guide portion toward the other surface side through the light guide portion. The method of claim 1,
The plurality of diffractive optical elements may include an input diffraction optical element that receives light from a light source and diffracts the received light so that the received light may be guided on the light guide portion, and receives the light diffracted from the input diffraction optical element. And an intermediate diffraction optical element configured to receive the received light one-dimensionally by diffraction, and to receive the light extended from the intermediate diffraction optical element, and to receive the received light from the optical guide by diffraction. An output diffraction optical element,
And the reduction layer is disposed on at least an output diffraction optical element side of the input diffraction optical element, the intermediate diffraction optical element, and the output diffraction optical element. The method according to claim 1 or 2,
The diffractive optical element in which the reduction layer is disposed has a lattice pattern having a period d and is disposed on one surface of the light guide portion.
The reference position is spaced apart from the bottom side of the diffraction optical element by a length B in a first direction from the bottom side of the diffraction optical element on which the reduction layer is disposed, by the length B, and is perpendicular to the first direction from one surface of the light guide portion and the other surface side. Is a position spaced apart by the length R from the one surface in a second direction toward the,
The reduction layer is a diffraction light guide plate module for reducing the rate at which the external light incident to the reference position in the reference wavelength band incident at an angle equal to or greater than the reference incident angle determined by the following [Condition 1]:
[Condition 1]

Where θ Is the reference incidence angle, λ is the minimum wavelength of the reference wavelength band, is the period of the grating pattern of the diffractive optical element on which the reduction layer is disposed, and B is between the lower side of the diffractive optical element on which the reduction layer is disposed and the reference position. The first reference shortest distance, R is the second reference shortest distance between one surface of the light guide portion and the reference position. The method of claim 3,
The reference wavelength band is 400 nm to 700 nm, diffraction light guide module. The method of claim 3,
The diffraction light guide module includes a first diffractive optical element for separating light having a wavelength of 550 nm or more and 700 nm or less, a second diffractive optical element for separating light having a wavelength of 400 nm or more and 550 nm or less and a light having a wavelength of 450 nm or more and 650 nm or less A plurality of diffraction light guide plates including at least one of the third diffractive optical elements separating the
The reference angle of incidence is determined based on a case in which d in [Condition 1] is selected as the longest period among the lattice pattern periods of the output diffraction optical elements included in the plurality of diffraction light guide plates. The method of claim 3,
The reduction layer,
A film formed elongated in a direction parallel to said first direction, comprising a micro louver film having a light transmitting portion and a light shielding portion arranged to cross each other in a direction parallel to said first direction. The method of claim 6,
The micro louver film, the thickness and the length of the light transmitting portion satisfies the following [Condition Formula 2], diffraction light guide plate module:
[Condition Formula 2]

Here, a is the thickness of the micro louver film, b is the length of the light transmitting portion. The method of claim 1,
The reduction layer includes a first linear polarizer; And an optical film comprising first and second non-linear spray-oriented liquid crystal films sequentially formed on the first linear polarizer. The method of claim 8,
The tilt factor of the first or second non-linear spray oriented liquid crystal film is less than 0.95 or greater than 1.05, the diffraction light guide plate module. The method of claim 8,
And the optical film further comprises a second linear polarizer disposed adjacent to the second non-linear spray oriented liquid crystal film. The method of claim 1,
The reduction layer includes a first linear polarizer; And an optical film including first and second liquid crystal films sequentially formed on top of the first linear polarizer and each including a linear spray oriented liquid crystal compound. The method of claim 11,
The optical film further comprises a second linear polarizer disposed adjacent to the second liquid crystal film, diffraction light guide plate module.

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