Light guide device

Abstract

A light guide device according to an embodiment of the present invention comprises: a plate unit in which light is totally reflected; and a first diffraction unit and a second diffraction unit disposed on the plate unit, wherein the light that enters into the plate unit is refracted toward the second diffraction unit by the first diffraction unit, the light residually reflected in the plate unit is diffracted to the outside by the second diffraction unit, the first diffraction unit has a first length in a first direction and a second length in a second direction perpendicular to the first direction, the second diffraction unit has a third length in the first direction, and the first length and the third length are different from each other.

Description

Light guide device

[0001] The present invention relates to a light guide device.

[0002] The camera module can sense light reflected from an object and generate an image based on the sensed light.

[0003] However, since camera modules generate images using light incident on the image sensor, they generally sense the image in the direction they are facing. If the camera module cannot reach the desired shooting location, this can be overcome through various methods, such as using a drone, utilizing a separate support structure, or employing a miniature camera module.

[0004] Nevertheless, the use of a light guide device is being devised in which, for design or aesthetic reasons, the camera module is not exposed externally, and the incident light is diffracted and the diffracted light is totally reflected so that the position of incidence and the position where the light is sensed are different.

[0005] However, when using a light guide device, if the light incident from within the light guide device is totally reflected to the image sensor and the efficiency of the moving light is not high, the image resolution will decrease or double image phenomena such as overlapping or blurring will occur in the image, so it is necessary for the ratio of the input and output of the incident light to satisfy a certain level.

[0006] In addition, the light guide device positioned facing the instrument panel to photograph the occupant's condition is positioned such that the camera module is positioned differently from the incident position of the light to prevent the camera module from obscuring the instrument panel.

[0007] However, in a light guide device including a diffraction part, the diffraction part diffracts some wavelengths in the overlap area with the display viewed by the user, and when the user views it, a sense of incongruity may be formed with the image of the display in the overlap area.

[0008] Since this causes discomfort to users looking at the display, a means to resolve this is necessary.

[0009] Since light loss occurs during the diffraction process of light incident on the light guide device, it is necessary to resolve the issue of light efficiency; furthermore, because this causes discomfort to the user viewing the display, a means to resolve this is required.

[0010] The present invention is an invention devised to solve the problems of the aforementioned prior art, and aims to improve the light efficiency of a waveguide.

[0011] In addition, the objective is to prevent the sense of strangeness caused by the diffraction of some wavelengths during the process in which light from the display enters the user's eyes.

[0012] The problems that the present invention aims to solve are not limited to those mentioned above, and other problems not mentioned herein will be clearly understood by those skilled in the art from the description below.

[0013] A light guide device according to an embodiment of the present invention for achieving the above-described purpose comprises a plate portion in which light is totally reflected internally, and a first diffraction portion and a second diffraction portion disposed on the plate portion, wherein the first diffraction portion diffracts the light incident into the interior of the plate toward the second diffraction portion, and the second diffraction portion diffracts the light totally reflected inside the plate toward the outside, wherein the second diffraction portion has a first length in a first direction and a second length in a second direction perpendicular to the first direction, and the first diffraction portion has a third length in the first direction, and the first length and the third length are different.

[0014] According to an embodiment of the present invention, the first length may be greater than the third length.

[0015] According to an embodiment of the present invention, the first length may be 2 to 14 times the third length.

[0016] According to an embodiment of the present invention, at least one of the first diffraction part and the second diffraction part may be a reflection-type diffraction element.

[0017] According to an embodiment of the present invention, the first diffraction part is a reflection-type diffraction element, and the amount of light diffracted by the first diffraction part may be 5% to 35% of the amount of light incident on the first diffraction part.

[0018] According to an embodiment of the present invention, the first diffraction part is a reflection-type diffraction element, and the amount of light diffracted by the first diffraction part may be 90% or more of the amount of light incident on the first diffraction part.

[0019] According to an embodiment of the present invention, the first angle corresponding to half the angle of view in the first diffraction section and the second angle corresponding to half the angle of view in the second diffraction section may correspond to the following [Equation 1].

[0020] [Mathematical Formula 1]

[0021]

[0022]

[0023] According to an embodiment of the present invention, the center of the first diffraction section and the center of the second diffraction section are spaced apart by the fourth length in the first direction, and the second length may correspond to the following [Equation 2].

[0024] [Mathematical Formula 2]

[0025]

[0026] In addition, a light guide device according to an embodiment of the present invention is a light guide device disposed between a display and an object, comprising a plate portion disposed facing the display, a first diffraction portion and a second diffraction portion disposed on the plate portion, and a control portion for adjusting the wavelength of the display, wherein the second diffraction portion diffracts light incident on the plate portion to the first diffraction portion, the first diffraction portion diffracts light reflected from within the plate portion to an external image sensor, the second diffraction portion diffracts at least a portion of the light directed from the display to the object, and the control portion adjusts the wavelength of the display differently in a first direction from the second diffraction portion toward the first diffraction portion.

[0027] According to an embodiment of the present invention, the display has a first diffraction section and an overlap area in the direction from the object toward the display, and the control section can adjust the wavelength within the overlap area differently.

[0028] According to an embodiment of the present invention, when the overlap area is divided into an upper part and a lower part based on any point of the overlap area in the first direction, the control unit can control the upper part of the overlap area to have a higher light intensity of a longer wavelength than the lower part of the overlap area.

[0029] According to an embodiment of the present invention, the control unit can control the wavelength of the overlap region along the first direction so that the light intensity of the long wavelength increases.

[0030] According to an embodiment of the present invention, the control unit can control the wavelengths of the center and the periphery of the overlap area differently in a second direction perpendicular to the first direction.

[0031] According to an embodiment of the present invention, the control unit can control the light intensity of the short wavelength at the center of the overlap region in the second direction to be higher than the wavelength of the region adjacent to the periphery of the overlap region in the second direction.

[0032] According to an embodiment of the present invention, the control unit can control the light intensity of a relatively short wavelength to be high in the lower region in the first direction and in the region adjacent to the center of the overlap region in the second direction perpendicular to the first direction, based on any point on the overlap region.

[0033] According to an embodiment of the present invention, the length of the display in the first direction may be longer than the length of the first diffraction part in the first direction.

[0034] According to an embodiment of the present invention, the length of the display in the first direction may be shorter than the length of the first diffraction part in the first direction.

[0035] According to an embodiment of the present invention, the control unit includes a sensing unit that detects the position of the object, and can adjust the wavelength of the display according to the position of the object detected by the sensing unit.

[0036] According to an embodiment of the present invention, the sensing unit can detect the position of the person's eyes when the object is a person.

[0037] The light guide device according to an embodiment of the present invention for solving the above problem may have the effect of improving the light efficiency of the wave guide.

[0038] In addition, it may have the effect of preventing the sense of strangeness caused by the diffraction of some wavelengths as light from the display enters the user's eyes.

[0039] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description in the claims.

[0040] The summary described above, as well as the detailed description of the preferred embodiments of the present application described below, will be better understood when read in conjunction with the accompanying drawings.

[0041] Preferred embodiments are illustrated in the drawings for the purpose of illustrating the present invention.

[0042] However, it should be understood that the present application is not limited to the exact arrangement and means depicted.

[0043] FIG. 1 is a drawing illustrated for the overall explanation of a light guide device according to an embodiment of the present invention;

[0044] FIG. 2 is a drawing showing the view of a light guide device according to an embodiment of the present invention as seen from V1 with reference to FIG. 1;

[0045] FIG. 3 is a drawing showing the view of a light guide device according to an embodiment of the present invention as seen from V2 with reference to FIG. 1;

[0046] FIG. 4 is a drawing illustrating the diffraction efficiency of the first diffraction section of a light guide device according to an embodiment of the present invention;

[0047] FIG. 5 is a drawing illustrating the diffraction efficiency according to the lengths of the first and second diffraction sections of a light guide device according to an embodiment of the present invention;

[0048] FIG. 6 is a diagram illustrating experimental results for deriving the efficiency of FIG. 5 of a light guide device according to an embodiment of the present invention;

[0049] FIG. 7 is a drawing illustrating an example of a double image of a light guide device according to an embodiment of the present invention;

[0050] FIG. 8 is a drawing illustrating the overall description of a light guide device disposed together with a display according to an embodiment of the present invention;

[0051] FIG. 9 is a drawing illustrating the control unit's adjustment of the display wavelength according to the first angle and the second angle of the light guide device disposed together with the display according to an embodiment of the present invention;

[0052] FIG. 10 is a drawing illustrating an overlap area generated according to the length of a first diffraction section of a light guide device disposed together with a display according to an embodiment of the present invention;

[0053] FIG. 11 is a drawing showing the diffraction efficiency according to the angle of incidence of light in a first diffraction section of a light guide device disposed together with a display according to an embodiment of the present invention;

[0054] FIG. 12 is a drawing illustrating the overlap area in FIG. 9 of a light guide device disposed together with a display according to an embodiment of the present invention;

[0055] FIG. 13 is a drawing illustrating the overlap area in FIG. 10 of a light guide device disposed together with a display according to an embodiment of the present invention; and

[0056] FIG. 14 is a drawing illustrating the positional arrangement of the first diffraction part and the second diffraction part in FIG. 8 of a light guide device arranged together with a display according to an embodiment of the present invention.

[0057] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the present invention to specific embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the present invention. In describing the present invention, detailed descriptions of related prior art are omitted if it is determined that such detailed descriptions may obscure the essence of the present invention.

[0058] Terms such as "first," "second," etc., may be used to describe various components, but said components should not be limited by said terms. These terms are used solely for the purpose of distinguishing one component from another.

[0059] The terms used in this application are used merely to describe specific embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, terms such as "comprising" or "having" are intended to indicate the presence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0060] Furthermore, throughout the specification, when the term "connected" is used, it does not mean only that two or more components are directly connected, but may also mean that two or more components are indirectly connected through other components, that they are connected not only physically but also electrically, or that they are a single unit although referred to by different names depending on their location or function.

[0061] Furthermore, when described as being formed or placed on the “top or bottom” of each component, “top or bottom” includes not only cases where two components are in direct contact with each other, but also cases where one or more other components are formed or placed between the two components. Additionally, when expressed as “top or bottom,” it may include the meaning of a downward direction as well as an upward direction relative to a single component.

[0062] Furthermore, when describing objects as "identical" or "similar" based on numerically or geometrically comparable properties such as length, inner diameter, diameter, or area, this may imply that there is a margin of error. For example, if it is stated that the lengths of components A and B are identical, it may be advisable to interpret this to mean that the length of B falls within the margin of error of the length of A. This takes into account the margin of error that occurs during the injection molding and manufacturing processes; since this is a matter that can occur physically and is self-evident, it is advisable to understand the description as "identical" or "similar" by considering the margin of error as described above. In this case, the margin of error may be within the range of -5% to +5% of the mentioned numerical value or shape, but this is merely an example of the margin of error and may not necessarily be limited to the stated range.

[0063] A preferred embodiment of the present invention, in which the objective of the present invention can be specifically realized, will be described below with reference to the attached FIGS. 1 to 7.

[0064] Specifically, FIG. 1 is a drawing illustrating an overall description of a light guide device according to an embodiment of the present invention; FIG. 2 is a drawing illustrating the view of the light guide device according to an embodiment of the present invention as seen from V1 based on FIG. 1; FIG. 3 is a drawing illustrating the view of the light guide device according to an embodiment of the present invention as seen from V2 based on FIG. 1; FIG. 4 is a drawing illustrating the diffraction efficiency of the first diffraction section of the light guide device according to an embodiment of the present invention; FIG. 5 is a drawing illustrating the diffraction efficiency according to the lengths of the first and second diffraction sections of the light guide device according to an embodiment of the present invention; FIG. 6 is a drawing illustrating experimental results for deriving the efficiency of FIG. 5 of the light guide device according to an embodiment of the present invention; and FIG. 7 is a drawing illustrating an example of a double image of the light guide device according to an embodiment of the present invention.

[0065] First, as shown in FIGS. 1 to 3, the light guide device according to an embodiment of the present invention includes a plate portion (100) in which light is totally reflected internally, a first diffraction portion (200) and a second diffraction portion (300) disposed on the plate portion (100). Here, the first diffraction portion (200) diffracts light incident into the interior of the plate portion (100) toward the second diffraction portion (300), and the second diffraction portion (300) diffracts light totally reflected internally within the plate portion (100) to the outside. At this time, the second diffraction portion (300) is an area where light totally reflected internally within the plate portion (100) moves to the outside, and the first diffraction portion (200) may be an area where light is incident from the outside.

[0066] Additionally, the second diffraction section (300) has a first length (L1) in the first direction and a second length (L2) in the second direction perpendicular to the first direction, the first diffraction section (200) has a third length (L3) in the first direction, and the second diffraction section (300) and the first diffraction section (200) may be spaced apart by a fourth length (L4) in the first direction.

[0067] At this time, the first direction may include both directions, such as the direction from the first diffraction section (200) toward the second diffraction section (300) and the direction from the second diffraction section (300) toward the first diffraction section (200). The first direction may include both directions, such as the direction from the upper side toward the lower side and the direction from the lower side toward the upper side, based on FIG. 1. The second direction may include both directions, such as the direction from one end toward the other end and the direction from the other end toward the first end, which are perpendicular to the first direction and perpendicular to the first direction with respect to the first diffraction section (200). The second direction may also mean the direction from left to right and from right to left with respect to FIG. 1. Additionally, the third direction may include both directions, such as the direction from left to right and from right to left, which are perpendicular to the first and second directions with respect to FIG. 2.

[0068] Meanwhile, half of the angle of view of the light incident on the second diffraction section (300) corresponds to the second angle (A2) as shown in FIG. 1, and half of the angle of view of the light incident on the first diffraction section (200) may correspond to the first angle (A1) as shown in FIG. 3. Additionally, the plate section (100) may have a thickness (T) in the third direction, and an internal space may be formed in which one surface and the other surface are separated by the thickness (T). Here, the angle of view of the first diffraction section (200) and the angle of view of the second diffraction section (300) described in the detailed description of the present invention can be understood as being determined based on the maximum angle of the light incident on the first diffraction section (200) and the second diffraction section (300), respectively. In addition, the incident light can be twice the maximum angle of the incident light, including both directions such as left and right or upper and lower, and the first angle (A1) can be the maximum angle of the light incident on the first diffraction section (200), and the second angle (A2) can be the maximum angle of the light incident on the second diffraction section (300).

[0069] To explain more simply, the angle of view at the first diffraction section (200) is the angle of view of light incident on the first diffraction section (200) from the outside, and the angle of view at the second diffraction section (300) may be the angle of view of light incident from the first diffraction section (200) to the second diffraction section (300). That is, although the target may be the same light, as the first diffraction section (200) and the second diffraction section (300) are separated, the angle at which the light diffracted from the first diffraction section (200) is incident on the second diffraction section (300) is limited, and the angle of view of the light incident on the second diffraction section (300), which is to be explained in the detailed description of the present invention, may be different from the angle of view of the light incident on the first diffraction section (200).

[0070] Alternatively, the angle of view of light incident on the first diffraction section (200) refers to the angle of view of light incident from the outside toward the first diffraction section (200), and the angle of view of light in the second diffraction section (300) is the angle of view of light diffracted from the first diffraction section (200) incident on the second diffraction section (300), so the angle of view in the second diffraction section (300) and the angle of view in the first diffraction section (200) may be different from each other.

[0071] To explain it more simply, based on the first diffraction section (200), the angle of view of the first diffraction section (200) can refer to the general angle of view of light incident on the first diffraction section (200), which can correspond to the angle of view of the camera module (C), and the second diffraction section (300) can have a relatively lower angle of view than the first diffraction section (200) when based only on the angle of view of the incident light. That is, as light is diffracted and incident from the first diffraction section (200) toward the second diffraction section (300), the light is relatively concentrated toward the second diffraction section (300), so they can have different angles of view.

[0072] Based on this, to describe the light guide device according to an embodiment of the present invention, as shown in FIG. 2, when light is incident on the first diffraction section (200), the first diffraction section (200) diffracts the light toward the interior of the plate section (100), more precisely, toward the second diffraction section (300), and since the angle of the light incident on the first diffraction section (200) is different for each light, the angle of diffraction may also be different from each other.

[0073] Accordingly, in the case of a light guide device according to the prior art, even though the first length (L1) and the third length (L3) of the second diffraction section (300) and the first diffraction section (200) are the same, there may be a problem in that the length of the second diffraction section (300) is relatively smaller than the area utilized, or the light does not meet the intended number of reflections and is incident on the camera module (C), forming a double image.

[0074] At this time, the double image refers to a phenomenon in which light with different reflection times inside the plate portion (100) is incident on the image sensor (C2), causing gaps between images to be formed or afterimages of images that did not previously exist to remain. When a double image is formed in this way, there may be a problem in that the resolution of the image is reduced and the image is difficult to utilize.

[0075] Unlike the light guide device according to the embodiment of the present invention, the lengths of the second diffraction section (300) and the first diffraction section (200) in the first direction are designed to be different from each other, and the number of reflections is satisfied, and the formation of a double image on the image sensor (C2) can be effectively blocked.

[0076] Referring to FIGS. 1 to 3, the second diffraction section (300) has a third length (L3) in the first direction, and the first diffraction section (200) has a first length (L1) in the first direction and a second length (L2) in the second direction. At this time, the first length (L1) is different from the second length (L2), and preferably, the first length (L1) may be larger than the second length (L2). More preferably, the first length (L1) may be 2 to 14 times the second length (L2).

[0077] Specifically, the first length (L1) is larger than the second length (L2), and the light diffracted from the first diffraction section (200) toward the second diffraction section (300) is reflected at different angles and incident on the second diffraction section (300), and the second diffraction section (300) may have a relatively smaller length because it diffracts the light to fit the area of ​​the image sensor (C2).

[0078] However, in addition to the design intent described above, the number of reflections is determined according to the ratio of the first length (L1) and the third length (L3). Since the diffraction efficiency is determined according to the first length (L1), it may be desirable to set the ratio of the first length (L1) and the third length (L3) to 2 to 14 times as described above in order to match the pre-set diffraction efficiency.

[0079] Referring to FIG. 4, when light incident on the first diffraction section (200) in the third direction is defined as the first light (D1), the first light (D1) that passes through the plate section (100) may be partially diffracted and partially transmitted at the incident plane of the first diffraction section (200). At this time, if the transmitted light is defined as the second light (D2) and the diffracted light as the third light (D3), the ratio of the second light (D2) and the third light (D3) of the first light (D1) may vary depending on the diffraction efficiency of the first diffraction section (200).

[0080] For example, when the first light (D1) is completely diffracted into the third light (D3) without the second light (D2) in the first diffraction section (200), the diffraction efficiency is 100%, and when the first light (D1) is transmitted to the second light (D2) by 50% of the amount of light and diffracted to the third light (D3) by 50% in the first diffraction section (200), the diffraction efficiency is 50%, and when the first light (D1) is diffracted to the third light (D3) by 10% and transmitted to the second light (D2) by 90% in the first diffraction section (200), the diffraction efficiency can be 10%.

[0081] At this time, the reflected third light (D3) is reflected from the plate portion (100) and incident again on the first diffraction portion (200), and the third light (D3) is dispersed again into the second light (D2) and the third light (D3), so that the amount of light gradually decreases compared to the incident first light (D1). That is, if the diffraction efficiency is high, the amount of light of the first light (D1) can be maintained while being incident on the second diffraction portion (300), but if the diffraction efficiency is low, the third light (D3) reaching the second diffraction portion (300) will inevitably have a relatively low amount of light.

[0082] To explain this differently, when the first light (D1) is incident, transmitted into the second light (D2) at the first diffraction section (200), and diffracted into the third light (D3), the point where the third light (D3) is reflected on the inner surface of the plate section (100) is defined as the first point (P1); another point where the third light (D3) is transmitted and diffracted again into the second light (D2) and the third light (D3) at the first diffraction section (200) and reflected on the inner surface of the plate section (100) is defined as the second point (P2); and another point where the third light (D3) reflected at the second point (P2) is transmitted and diffracted again into the second light (D2) and the third light (D3) at the first diffraction section (200) and reflected on the inner surface of the plate section (100) is defined as the third point at the first point (P1). The amount of light (D3) is higher than the amount of light of the third light (D3) at the second point (P2) and the third point (P3), and the amount of light of the third light (D3) at the second point (P2) is smaller than the amount of light of the third light (D3) at the first point (P1) and larger than the amount of light of the third light (D3) at the third point (P3), and the amount of light of the third light (D3) at the third point (P3) may be smaller than the amount of light of the third light (D3) at the first point (P1) and the second point (P2).

[0083] However, when the first diffraction part (200) is a reflection-type diffraction element, the light incident on the first diffraction part (200) is not reflected through only one path as shown in FIG. 4. Therefore, another first light (D1) is incident at the position where the third light (D3) reflected from the first point (P1) is incident on the second diffraction part (300), so the second light (D2) is transmitted and the third light (D3) is diffracted. Thus, the amount of light of the third light (D3) at the second point (P2) can maintain a relatively similar amount of light as the first light (D1). Additionally, the third light (D3) reflected from the second point (P2) is incident on the first diffraction section (200) along with another first light (D1). Since the incident first light (D1) transmits the second light (D2) and diffracts the third light (D3), the amount of light from the third light (D3) at the third point (P3) can have a relatively similar amount of light to that of the first light (D1).

[0084] Consequently, the third light (D3) may be moved to the second diffraction section (300) without substantial loss of light quantity according to the incident first light (D1), but in order to satisfy this precondition, the first length (L1) of the first diffraction section (200) must be sufficiently large so that the loss of light quantity of the first light (D1) can be minimized, and thus it may correspond to the length of the first diffraction section (200).

[0085] However, if the first length (L1) of the first diffraction section (200) becomes excessively large, the fourth length (L4) between the first diffraction section (200) and the second diffraction section (300) is reduced, and the position of the light incident on the camera module (C) becomes similar to the position of the light incident on the camera module (C), so there may be a problem in that the same effect as a general camera is obtained.

[0086] Additionally, the light guide device is generally formed such that the plate portion (100) is made of a transparent material so that one side and the other side can be seen through each other. However, in order to solve this problem, if the diffraction efficiency is increased to an extreme degree, there may be a problem in that there is no light passing through the first diffraction portion (200), so the light from the first diffraction portion (200) cannot be seen from the opposite side.

[0087] That is, it is desirable that the diffraction efficiency of the first diffraction section (200) be relatively low so that it can be transmitted to the opposite side without being extremely high, and the amount of light of the third light (D3) diffracted by the first diffraction section (200) may be 3% to 50% of the amount of light incident on the first diffraction section (200). Preferably, the amount of light of the third light (D3) diffracted by the first diffraction section (200) may be 4% to 40% of the amount of light incident on the first diffraction section (200), and more preferably 5% to 35%.

[0088] Alternatively, as illustrated in FIG. 5, if the first length (L1) increases to an extreme degree according to the ratio of the first length (L1) and the third length (L3), the diffraction efficiency may be 1, that is, close to 100%. However, if the first length (L1) increases to an extreme degree, the second diffraction section (300) increases in proportion to the incident area of ​​the first diffraction section (200), so there may be a problem in that the self-area of ​​the second diffraction section (300) and the first diffraction section (200) correspond to each other.

[0089] Therefore, it may be desirable to adjust the diffraction efficiency of the second diffraction section (300) and the first diffraction section (200) to an appropriate level, design the ratio of the first length (L1) and the third length (L3) to be 2:1 to 14:1, and set the diffraction efficiency to 5% to 35%.

[0090] In addition, as previously described, when the diffraction efficiency is extremely high, the user cannot see the opposite side of the plate portion (100) through the first diffraction portion (200). Therefore, it is desirable to maintain the diffraction efficiency of the first diffraction portion (200) within a range that does not feel unnatural. This can be achieved by considering various design conditions, such as the number of reflections, diffraction efficiency, the fourth length (L4), the angle of view in the second diffraction portion (300), and the angle of view in the first diffraction portion (200), through the ratio of the first length (L1) and the third length (L3) of the second diffraction portion (300) and the first diffraction portion (200), thereby forming design conditions as shown in FIG. 5.

[0091] For example, it is possible to increase the light efficiency under conditions where there is no sense of disparity by securing low diffraction efficiency rather than high diffraction efficiency, but increasing the first length (L1), or it is possible to secure a region where the first length (L1) of the first diffraction section (200) is excessively long by adjusting the length ratio of the second diffraction section (300) and the first diffraction section (200) to a certain level while maintaining a somewhat high diffraction efficiency, and this may not necessarily be limited. However, as described above, since the first length (L1) becomes excessively long in the section where the diffraction efficiency is low rather than in the condition where the diffraction efficiency is high, it may be desirable to set the first length (L1) within the diffraction efficiency range of 5% to 35% as described above.

[0092] Here, if the first length (L1) is less than twice the third length (L3), the diffraction efficiency is 35% or more, and due to the relatively high diffraction efficiency, a user looking at the plate portion (100) may form a sense of strangeness regarding the first diffraction portion (200). Also, because the fourth distance (L4) between the second diffraction portion (300) and the first diffraction portion (200) becomes excessively close due to problems such as the third length (L3) increasing in proportion to the first length (L1) or the first length (L1) decreasing in proportion to the third length (L3), it may be desirable for the first length (L1) to be at least twice the third length (L3).

[0093] In addition, if the first length (L1) is 14 times or more than the third length (L3), the diffraction efficiency is 5% or less, and due to the relatively low diffraction efficiency, there may be an advantage that a user looking at the plate portion (100) does not feel the strangeness of the first diffraction portion (200). However, since the first length (L1) is 14 times or more than the third length (L3), there is a disadvantage that the overall volume of the product increases or the fourth length (L4) becomes excessively short, and if the third length (L3) is reduced to match the first length (L1), a problem may arise that the design according to the light incident area of ​​the camera module (C) is not satisfied, so it may be desirable for the first length (L1) to be at most 14 times or less than the third length (L3).

[0094] In addition, since the third length (L3) is designed considering external factors such as the size of the image sensor (C2) and the size of the camera module (C), the third length (L3) is fixed in the design conditions, and it may be desirable to set the length considering the diffraction efficiency by matching the first length (L1) to the third length (L3).

[0095] However, depending on the design conditions, there are cases where high diffraction efficiency is required, and in such cases, conditions satisfying a diffraction efficiency of 90% or more may be required.

[0096] In addition, as shown in FIG. 1 and FIG. 3, since the second angle (A2) corresponding to half of the angle of view in the second diffraction section (300) changes according to the fourth length (L4) and the second length (L2), it may be desirable to design the second length (L2) to correspond to the fourth length (L4).

[0097] Specifically, the first length (L1) may be 2 to 14 times the third length (L3), and the second length (L2) corresponds to the second length (L2) of the first diffraction part (200) when using trigonometric functions based on the second angle (A2), by multiplying tan(second angle (A2)) by the fourth length (L4) and doubling it, and the second angle (A2) can be calculated through arcsin. More specifically, the second angle (A2) may correspond to [Equation 1] below.

[0098] [Mathematical Formula 1]

[0099]

[0100]

[0101] At this time, as described above, since the second length (L2) can be calculated using tan(second angle (A2)) based on the second angle (A2), the second length (L2) can correspond to [Equation 2] below.

[0102] [Mathematical Formula 2]

[0103]

[0104] That is, the second length (L2) corresponds to the fourth length (L4) and the second angle (A2), and since the second angle (A2) is half the angle of view at the second diffraction section (300), the second length (L2) can correspond to the fourth length (L4) and the angle of view of the second diffraction section (300).

[0105] To explain this more specifically, refer to Fig. 6.

[0106] In FIG. 6, relative efficiency refers to the efficiency of the amount of light directed from the first diffraction section (200) to the second diffraction section (300) relative to the amount of incident light. When classified according to the efficiency of the first diffraction section (200), if the diffraction efficiency of the first diffraction section (200) is 5%, the user looking at the plate section (100) does not feel any strangeness as described above. However, as the amount of light directed to the second diffraction section (300) gradually increases, it shows very low efficiency when the first length (L1) is twice the third length (L3), but it can be confirmed that the relative efficiency is high when the first length (L1) is 14 times the third length (L3). In addition, when the diffraction efficiency of the first diffraction section (200) is 5%, it can be seen that the relative efficiency increases according to the ratio of the first length (L1) and the third length (L3), but with a relatively gentle slope, and this may have the advantage of making it easy to adjust the relative efficiency through the ratio of the first length (L1) and the third length (L3) as described above.

[0107] Meanwhile, when the diffraction efficiency of the first diffraction section (200) is 10%, it can be confirmed that when the first length (L1) is twice the third length (L3), a relatively higher amount of light is transmitted to the second diffraction section (300) than when the diffraction efficiency of the first diffraction section (200) is 5%. In addition, compared to the case where the diffraction efficiency of the first diffraction section (200) is 5%, it has a relatively high relative efficiency in the ratio of the first length (L1) to the third length (L3), but since it has a relatively gentle slope similar to when the diffraction efficiency of the first diffraction section (200) is 5%, there may be an advantage in that the ratio of the first length (L1) to the third length (L3) can be adjusted more easily.

[0108] Meanwhile, when the diffraction efficiency of the first diffraction section (200) is 20%, it has a relatively high relative efficiency in relation to the first length (L1) and the third length (L3) compared to the case where the diffraction efficiency of the first diffraction section (200) is 10%. However, since it has a relatively gentle slope similar to when the diffraction efficiency of the first diffraction section (200) is 10%, there may be an advantage in that the ratio of the first length (L1) and the third length (L3) can be adjusted more easily. Additionally, when the diffraction efficiency of the first diffraction section (200) is 20%, the overall diffraction efficiency is relatively low, so the user may feel a somewhat strange sensation. However, there may be an advantage in that it can have high efficiency while feeling relatively less strange sensation from the first diffraction section (200) formed on the plate section (100).

[0109] In addition, to explain the case where the diffraction efficiency of the first diffraction section (200) is 30% and the case where the diffraction efficiency is 40%, it can be seen that the relative efficiency increases rapidly according to the ratio of the first length (L1) and the third length (L3) when the diffraction efficiency of the first diffraction section (200) is 30%. Since the ratio of the first length (L1) and the third length (L3) must be precisely set to match the relative efficiency, there may be a disadvantage that it requires high technical skill and precision compared to when the diffraction efficiency of the first diffraction section (200) is relatively low. However, when the diffraction efficiency of the first diffraction section (200) is 30%, the relative efficiency does not reach 100% when the first length (L1) is 14 times the third length (L3), so it is possible to identify an object behind by penetrating the first diffraction section (200) and the plate section (100), but when the diffraction efficiency of the first diffraction section (200) is 40%, the relative efficiency approaches 100% when the first length (L1) is 8 times the third length (L3), so it may be difficult to adjust the first length (L1) of the first diffraction section (200) to match the ratio with the third length (L3).

[0110] For example, if the first length (L1) of the first diffraction section (200) must be relatively large due to design conditions, as described above, the third length (L3) must be increased in proportion to the first length (L1) as the first diffraction section (200) has higher efficiency, or the first length (L1) must be reduced, so there may be problems where the product becomes larger overall or deviates from the design intent. Alternatively, for example, the first diffraction section (200) is positioned to be exposed to the outside because it receives external light and diffracts the light toward the second diffraction section (300), but the second diffraction section (300) can be positioned so as not to be exposed to the outside because it diffracts the incident light toward the camera module (C). In such a case, the first diffraction section (200) occupies a relatively large area of ​​the plate section (100), so that the exposed plate section (100) appears to have the same shape as the first diffraction section (200), and there is a design intention to identify an object behind the plate section (100) that has passed through it. In this case, the first length (L1) must be long, and since the object cannot be identified if the relative efficiency is excessively high, the third length (L3) increases together with the first length (L1), and the area of ​​the plate section (100) that is not exposed increases in proportion to this, which may result in a problem of deviating from the design intention.

[0111] Therefore, it is preferable that the diffraction efficiency of the first diffraction unit (200) be 5% to 35% or less. Since there is a disadvantage that the amount of light directed toward the camera module (C) becomes excessively low due to the excessively low relative efficiency when the diffraction efficiency of the first diffraction unit (200) is 5% or less, as described above, it may be preferable that the diffraction efficiency of the first diffraction unit (200) be at least 5% and at most 35% or less.

[0112] Consequently, satisfying the condition that the diffraction efficiency of the first diffraction section (200) is 5% to 35% or less corresponds to the most desirable range in terms of the design intent of the product and the smoothness of the overall design of the product. If it deviates from this range, as described above, it may cause problems such as the size of the product, the amount of light transmitted to the camera module (C), and the increased precision of the design. Therefore, the first diffraction section (200) of the light guide device according to the embodiment of the present invention can be designed to have a diffraction efficiency of 5% to 35% or less as described above to prevent the problems described above.

[0113] Meanwhile, as illustrated in FIG. 7, if the ratio of the first length (L1) and the third length (L3) of FIG. 5 is not matched, generally the light reflected N times is incident on the second diffraction section (300), and the light reflected N times forms an image on the image sensor (C2) by the lens section (C1). However, if the light reflected N times is diffracted at a different time than N times, for example, the N+2 times, the light reflected at the first diffraction section (200) is refracted by the lens section (C1) into a different light path than the designed light path, and a disparity may be formed on the image sensor (C2).

[0114] Specifically, in the case of an image photograph formed through an image sensor (C2), the first section (S1) and the third section (S3) of the image photograph are images formed on the image sensor (C2) by light reflected N times being refracted by the lens part (C1), but even though the light reflected N+2 times should form an image in the second section, it is refracted toward the first section (S1) or the third section (S3) to form a black area in the third section (S3), and blurring such as a shadow may be formed in the first section (S1) and the third section (S3) due to the formation of the black area.

[0115] That is, if the ratio of the first length (L1), the third length (L3), and the second length (L2) described above is clear and the diffraction efficiency is not maintained, some of the light incident on the second diffraction section (300) is reflected N+2 times and incident, as illustrated, and this forms a black area such as the third section (S3) in the image, and forms a shadow image or blurring in the first section (S1) and the third section (S3), which may cause a problem of degrading the overall resolution and quality of the image.

[0116] Accordingly, the first diffraction section (200) of the light guide device according to an embodiment of the present invention has a diffraction efficiency of 5% to 35%, the first length (L1) is 2 to 14 times the third length (L3), and if the second length (L2) is designed through the above-described [Equation 1] and [Equation 2], there may be an advantage of effectively maintaining the diffraction efficiency while preventing the above-described double image problem.

[0117] Meanwhile, to explain the light guide device facing the display according to an embodiment of the present invention, reference may be made to FIGS. 8 to 14.

[0118] Specifically, FIG. 8 is a drawing illustrating an overall description of a light guide device arranged with a display according to an embodiment of the present invention; FIG. 9 is a drawing illustrating the control unit's control of the display wavelength according to the first angle and the second angle of the light guide device arranged with a display according to an embodiment of the present invention; FIG. 10 is a drawing illustrating an overlap area generated according to the length of the first diffraction section of the light guide device arranged with a display according to an embodiment of the present invention; FIG. 11 is a drawing illustrating the diffraction efficiency according to the angle of incidence of light on the first diffraction section of the light guide device arranged with a display according to an embodiment of the present invention; FIG. 12 is a drawing illustrating the overlap area in FIG. 9 of the light guide device arranged with a display according to an embodiment of the present invention; FIG. 13 is a drawing illustrating the overlap area in FIG. 10 of the light guide device arranged with a display according to an embodiment of the present invention; and FIG. 14 is a drawing illustrating the positional arrangement of the first diffraction section and the second diffraction section in FIG. 8 of the light guide device arranged with a display according to an embodiment of the present invention.

[0119] First, the light guide device according to an embodiment of the present invention is positioned between a display (D) and an object as shown in FIG. 8 and includes a plate portion (100) positioned facing the display (D), a first diffraction portion (200) and a second diffraction portion (300) positioned on the plate portion (100), and a control portion for controlling the wavelength of the display (D). Here, the first diffraction portion (200) diffracts light incident on the plate portion (100) to the second diffraction portion (300), and the second diffraction portion (300) diffracts light reflected from inside the plate portion (100) to an external image sensor.

[0120] Here, each of the first diffraction section (200) and the second diffraction section (300) may include a grating pattern having an inclination on the incident plane where light is incident. Additionally, the first diffraction section (200) may be of the transmission type, and the second diffraction section (300) may be of the reflection type. That is, light incident on the inside of the plate section (100) may be diffracted at the incident plane of the first diffraction section (200) and totally reflected inside the plate section (100), and light incident on the incident plane of the second diffraction section (300) may be diffracted toward the outside of the plate section (100), preferably toward the image sensor of the camera module (400).

[0121] In addition, the display (D) may be a vehicle instrument panel. In the detailed description of the present invention, to facilitate a smooth understanding of the light guide device according to an embodiment of the present invention, the display (D) is assumed to be an instrument panel. However, this is merely an example to aid in understanding the light guide device according to an embodiment of the present invention and is not necessarily limited thereto.

[0122] In addition, generally, light incident on the first diffraction section (200) is reflected at the same angle as the light diffracted in the second diffraction section (300), and the angle at which the camera module (400) is tilted relative to the plate section (100) may vary depending on the angle of light incident on the first diffraction section (200).

[0123] That is, when the area is divided into a region facing the second diffraction section (300) and a region opposite to the direction facing the second diffraction section (300) based on an incident virtual line perpendicular to the incident plane of the first diffraction section (200), in order for the light incident from the first diffraction section (200) to be diffracted at the second diffraction section (300) and directed toward the camera module (400), the light in the region facing the second diffraction section (300) is not diffracted, and only the light incident from the region opposite to the direction facing the second diffraction section (300) can be diffracted toward the second diffraction section (300).

[0124] Specifically, a plurality of incident virtual lines perpendicular to the incident plane of the first diffraction section (200) may be formed along the longitudinal direction of the first diffraction section (200), that is, in the direction from the first diffraction section (200) toward the second diffraction section (300), and based on each incident virtual line, the area toward the second diffraction section (300) described above and the area opposite to the direction toward the second diffraction section (300) may be divided.

[0125] At this time, the light incident on the first diffraction section (200) is diffracted from the first diffraction section (200) to the second diffraction section (300) only in the region opposite to the direction toward the second diffraction section (300) centered on the incident imaginary line perpendicular to the incident plane of the first diffraction section (200), and the light diffracted from the second diffraction section (300) and incident on the camera module (400) can also be incident only in the region opposite to the direction toward the second diffraction section (300) centered on the incident imaginary line perpendicular to the incident plane of the first diffraction section (200).

[0126] That is, if the angle in the direction toward the second diffraction section (300) relative to the incident imaginary line is defined as a negative angle and the angle in the opposite direction toward the second diffraction section (300) is defined as a positive angle, then only light having a positive angle of incidence relative to the incident imaginary line can be incident on the first diffraction section (200), or alternatively, light diffracted from the second diffraction section (300) and incident on the camera module (400), and light having a zero or negative angle of incidence relative to the incident imaginary line can not be incident on the camera module (400).

[0127] Meanwhile, the first diffraction unit (200) diffracts the incident light, and since the first diffraction unit (200) diffracts only some wavelengths depending on the angle at which the light is incident on the first diffraction unit (200), the light incident on the user's field of vision via the first diffraction unit (200) in the display (D) may have some wavelengths of light diffracted by the first diffraction unit (200), thereby creating a sense of incongruity with respect to the overall display (D) image.

[0128] To explain in detail, the first diffraction unit (200) diffracts at least a portion of the light directed from the display (D) toward the object, and the light diffracted by the first diffraction unit (200) is incident on the object at a lower angle depending on the angle of incidence of the first diffraction unit (200), so that it may have a color different from the original image.

[0129] In order to solve such problems, the light guide device according to the embodiment of the present invention can prevent a sense of unfamiliarity by adjusting the wavelength of the display (D) differently through the control unit so that even if the light of the image displayed on the display (D) is transmitted to the user via the first diffraction unit (200), the original image shape can be seen.

[0130] To explain this in detail, as illustrated in FIG. 8, assuming that the display (D) is, for example, an instrument panel, the display (D) is always positioned relatively lower than the user's field of vision, and at least some of the light from the display (D) can pass through the first diffraction unit (200) and be incident on the user's field of vision. Accordingly, the first diffraction unit (200) can diffract the wavelength of light according to the angle from any point on the display (D) toward the user's field of vision.

[0131] More specifically, the display (D) has a first diffraction section (200) and an overlap area (O) in the direction from the object toward the display (D), and the control unit can adjust the wavelength within the overlap area (O) differently. Here, the overlap area (O) varies depending on the user, i.e., the object's field of view and the area of ​​the first diffraction section (200) and the display (D). First, to explain the case where the area of ​​the first diffraction section (200) is larger than the area of ​​the display (D), refer to FIG. 9.

[0132] Specifically, as illustrated in FIG. 9, the fifth length (L5) of the display (D) in the first direction, which is the direction from the first diffraction section (200) toward the second diffraction section (300) and from the second diffraction section (300) toward the first diffraction section (200), is smaller than the sixth length (L6) in the first direction of the first diffraction section (200), and the third angle (A3) between any point in the upper region of the display (D) and the user's field of vision may be larger than the fourth angle (A4) between any point in the lower region of the display (D) and the user's field of vision. That is, because the third angle (A3) and the fourth angle (A4) are different from each other, the wavelength diffracted from the first diffraction section (200) is different, and the image of the display (D) may be transmitted distorted in the user's field of vision.

[0133] Accordingly, the user may feel a sense of strangeness regarding the image transmitted by the display (D), and if the display (D) is a dashboard as described above, an accident may occur due to this sense of strangeness; therefore, the control unit can adjust the wavelength of the display (D) differently by compensating for the wavelength diffracted from the first diffraction unit (200) according to the third angle (A3) and the fourth angle (A4).

[0134] As will be explained in more detail through the drawings to be described later, when the first wavelength is diffracted by the first diffraction unit (200) in the upper region of the display (D) having a third angle (A3) and the first wavelength becomes relatively lower, the control unit can control the first wavelength to be strongly output in the upper region of the display (D) having a third angle (A3), and when the second wavelength is diffracted by the first diffraction unit (200) in the lower region of the display (D) having a fourth angle (A4) and the second wavelength becomes relatively lower, the control unit can control the second wavelength to be strongly output in the lower region of the display (D) having a fourth angle (A4).

[0135] To express this differently, the third angle (A3) is the angle between the display (D) and the virtual line from any point to the user's field of view, and thus differs from the angle of incidence of the first diffraction unit (200). When explained based on the angle of incidence to the first diffraction unit (200), the angle of incidence to the first diffraction unit (200) may be smaller at an arbitrary point having the fourth angle (A4) than at an arbitrary point having the third angle (A3).

[0136] At this time, the reference for the angle of incidence incident on the first diffraction unit (200) from the display (D) described in the detailed description of the present invention is the angle between the first diffraction unit (200) and a virtual line directed toward the user's field of view from any point on the display (D). More specifically, among the angle directed toward the second diffraction unit (300) and the angle directed toward the opposite direction of the second diffraction unit (300) based on the virtual line, it may be preferable to consider the angle directed toward the opposite direction of the second diffraction unit (300) as the angle of incidence. The explanation regarding the angle of incidence to be described later will be explained based on this.

[0137] Meanwhile, referring to FIG. 10, when the sixth length (L6) in the first direction of the first diffraction part (200) is smaller than the fifth length (L5) in the first direction of the display (D), the display (D) forms an overlap area (O) that is smaller than the display (D), and the seventh length (L7) in the first direction of the overlap area (O) may be smaller than the fifth length (L5) and the sixth length (L6).

[0138] Here, the fifth angle (A5) between any point in the upper region of the overlap area (O) and the display (D) and the sixth angle (A6) between any point in the lower region of the overlap area (O) and the display (D) are different from each other, and the fifth angle (A5) is larger than the sixth angle (A6). This means that, from the perspective of the first diffraction unit (200), the angle of incidence of light directed toward the user's field of vision from any point having the fifth angle (A5) is smaller than the angle of incidence of light directed toward the user's field of vision from any point having the sixth angle (A6). Accordingly, the control unit can prevent a sense of strangeness by adjusting the wavelength within the overlap area (O) differently.

[0139] In addition, in FIG. 9, when the fifth length (L5) is smaller than the sixth length (L6), the entire display (D) becomes an overlap area (O), and the entire display (D) can be controlled to minimize the sense of disparity. However, when the fifth length (L5) is larger than the sixth length (L6), the overlap area (O) is formed in a part of the display (D), so the control unit needs to more finely control the light of the display (D) image transmitted without passing through the first diffraction unit (200) and the light of the display (D) image transmitted through the first diffraction unit (200).

[0140] For a more detailed explanation of this, refer to FIG. 11. FIG. 11 illustrates the diffraction efficiency of the first diffraction unit (200) according to the angle of incidence on the first diffraction unit (200). To explain this, when incident on the first diffraction unit (200) at a relatively small angle of incidence, the diffraction efficiency of the long wavelength is high and the diffraction efficiency of the short wavelength is low, so the long wavelength is diffracted; and when incident on the first diffraction unit (200) at a relatively large angle of incidence, the diffraction efficiency of the short wavelength is high and the diffraction efficiency of the long wavelength is low, so the short wavelength can be diffracted.

[0141] That is, as shown in FIG. 11, depending on the angle of incidence on the first diffraction section (200), some wavelengths may have their intensity reduced during the process of moving to the user, and some wavelengths may not be transmitted at all and may be diffracted at the first diffraction section (200). That is, depending on the angle from the display (D) toward the user's field of vision, some areas may have insufficient long wavelengths transmitted, and some areas may have insufficient short wavelengths transmitted.

[0142] For example, based on FIG. 11, when incident on the first diffraction section (200) at a relatively small angle, the short wavelength is not diffracted due to low diffraction efficiency and is transmitted to the user, but the long wavelength is diffracted due to high diffraction efficiency and is not properly transmitted to the user, and when incident on the first diffraction section (200) at a relatively large angle, the long wavelength is not diffracted due to low diffraction efficiency and is effectively transmitted to the user, but the short wavelength may not be properly transmitted to the user due to high diffraction efficiency.

[0143] In other words, when incident at a relatively small angle on the first diffraction section (200), short wavelengths are transmitted with high efficiency, but long wavelengths are partially lost and transmitted with low efficiency, and when incident at a relatively large angle on the first diffraction section (200), long wavelengths are transmitted with high efficiency, but short wavelengths are partially lost and transmitted with low efficiency.

[0144] Based on this, to reiterate FIGS. 9 and FIGS. 10, in FIGS. 9, the fifth length (L5) of the display (D) is smaller than the sixth length (L6) of the first diffraction section (200), so the entire display (D) forms an overlap area (O). Since light incident on the user with a third angle (A3) with the display (D) is incident at a relatively small angle from the first diffraction section (200), short wavelengths can be properly transmitted to the user, but long wavelengths may not be properly transmitted due to high diffraction efficiency. Additionally, since light incident on the user with a fourth angle (A4) with the display (D) is incident at a relatively large angle from the first diffraction section (200), long wavelengths can be properly transmitted to the user, but short wavelengths may not be properly transmitted due to high diffraction efficiency.

[0145] In other words, in such a situation, the control unit can increase the intensity of long wavelengths in the upper region because long wavelengths are not properly transmitted there, and increase the intensity of short wavelengths in the lower region because short wavelengths are not properly transmitted there.

[0146] Meanwhile, in FIG. 10, since the fifth length (L5) of the display (D) is greater than the sixth length (L6) of the first diffraction section (200), an overlap area (O) is formed in part of the display (D). Since light incident on the user with a fifth angle (A5) with the display (D) is incident at a relatively small angle from the first diffraction section (200), short wavelengths can be properly transmitted to the user, but long wavelengths may not be properly transmitted due to high diffraction efficiency. Additionally, since light incident on the user with a sixth angle (A6) with the display (D) is incident at a relatively large angle from the first diffraction section (200), long wavelengths can be properly transmitted to the user, but short wavelengths may not be properly transmitted due to high diffraction efficiency.

[0147] In other words, in such a situation, the control unit can increase the intensity of long wavelengths in the upper region because long wavelengths are not properly transmitted there, and increase the intensity of short wavelengths in the lower region because short wavelengths are not properly transmitted there.

[0148] To explain this in more detail, refer to Figs. 12 and 13.

[0149] First, referring to FIG. 13 illustrated with respect to FIG. 9, since the fifth length (L5) of the display (D) is smaller than the sixth length (L6) of the first diffraction section (200), an overlap area (O) is formed within the first diffraction section (200) as shown in FIG. 13, and all light transmitted to the user from the display (D) may have some wavelengths diffracted depending on the angle of incidence on the first diffraction section (200).

[0150] Based on this, if we explain based on a random point (LP) within the overlap area, the lower area relative to the random point (LP) may not properly transmit short wavelengths, and the upper area may not properly transmit long wavelengths. Accordingly, when the control unit adjusts the wavelength of the display (D) differently, regardless of where the random point (LP) is located within the overlap area (O), the intensity of long wavelengths in the upper area relative to the random point (LP) may be stronger than in the lower area, and the intensity of short wavelengths in the lower area may be stronger than in the upper area.

[0151] To explain this simply, the intensity of the long wavelength gradually increases in the direction toward the upper region in the first direction relative to the first center (C-1) of the overlap region (O) when the fifth length (L5) is smaller than the sixth length (L6), and the intensity of the short wavelength gradually increases in the direction toward the lower region in the first direction.

[0152] At this time, considering the second direction perpendicular to the first direction, the angle of incidence into the user's field of vision from a point farther away from the first center (C-1) in the second direction is a relatively small angle, while the angle of incidence into the user's field of vision from the first center (C-1) is a relatively large angle. Based on this, the control unit can control the intensity of the long wavelength more strongly as it moves further away from the first center (C-1) in the second direction. Additionally, when the fifth length (L5) is smaller than the sixth length (L6), the area of ​​the overlap area (O) and the area of ​​the display (D) are equal, so it may be easy to control the wavelength for the entire overlap area (O).

[0153] If, as shown in FIG. 13, the fifth length (L5) is greater than the sixth length (L6), an overlap area (O) is formed only in a part of the display (D), and when a random point (LP) is designated within the overlap area (O), as shown in FIG. 12, the upper area in the first direction relative to the random point (LP) may have a strong long wavelength intensity, and the lower area in the first direction may have a strong short wavelength intensity. Additionally, as described above, in the second direction relative to the random point (LP), the side facing the periphery of the overlap area (O) may have a strong long wavelength intensity, and the side facing the center of the overlap area (O) may have a strong short wavelength intensity.

[0154] To explain based on the second center (C-2) of the overlap area (O) in Fig. 13, the intensity of the long wavelength gradually increases in the direction toward the upper region in the first direction, and the intensity of the short wavelength gradually increases in the direction toward the lower region in the first direction.

[0155] At this time, considering the second direction perpendicular to the first direction, the angle of incidence into the user's field of vision from a point farther away from the second center (C-2) in the second direction is a relatively small angle, while the angle of incidence into the user's field of vision from the first center (C-1) may be a relatively large angle. Based on this, the control unit can control the intensity of the long wavelength more strongly as it moves further away from the second center (C-2) in the second direction. However, since the fifth length (L5) is larger than the sixth length (L6), the area of ​​the overlap region (O) is smaller than the area of ​​the display (D), and more precise control may be required to avoid creating a sense of disparity regarding the boundary line between the display (D) and the overlap region (O).

[0156] To summarize the above description and explain the control unit, the control unit controls the wavelength of the display (D) differently for each region, and controls the intensity of the long wavelength to gradually increase from the lowest part of the overlap region (O) toward the upper part of the first direction. Accordingly, the upper part of the first direction can be controlled so that the intensity of the long wavelength is the strongest among the regions of the first direction, and the lower part of the first direction can be controlled so that the intensity of the short wavelength is the strongest among the regions of the first direction.

[0157] Additionally, the control unit controls the intensity of the long wavelength to be stronger as it moves further away from the center of the overlap area (O) in the second direction, and the outermost part of the overlap area (O) in the second direction, that is, the area furthest from the center, has the strongest intensity of the long wavelength among the areas in the second direction, while the center has the strongest intensity of the short wavelength among the areas in the second direction.

[0158] In this way, by adjusting the wavelength intensity of the overlap area (O) differently for each area, the sense of unfamiliarity felt by the user can be prevented.

[0159] Meanwhile, although the first diffraction section (200) in FIG. 8 is depicted as being of the transmission type and the second diffraction section (300) as being of the reflection type, as shown in FIG. 14, the first diffraction section (200) may be of the reflection type and the second diffraction section (300) may be of the transmission type, and although not depicted, both the first diffraction section (200) and the second diffraction section (300) may be of the reflection type, or both the first diffraction section (200) and the second diffraction section (300) may be of the transmission type. That is, the types of the first diffraction section (200) and the second diffraction section (300) in FIG. 8 and FIG. 14 should not be interpreted as being limited only to what has been mentioned and depicted.

[0160] We have examined preferred embodiments according to the invention, and it is obvious to those skilled in the art that, in addition to the embodiments described above, the invention may be embodied in other specific forms without departing from the spirit or scope thereof.

[0161] Therefore, the embodiments described above should be regarded as exemplary rather than limiting, and accordingly, the present invention is not limited to the description above but may be modified within the scope of the appended claims and their equivalents.

Claims

A plate portion in which light is totally reflected from the inside; and It includes a first diffraction part and a second diffraction part disposed on the above plate part, and The above first diffraction section is, The light incident into the interior of the plate portion is diffracted toward the second diffraction portion, and The above second diffraction section is, The light reflected from within the above plate portion is diffracted to the outside, The first diffraction section has a first length in a first direction and a second length in a second direction perpendicular to the first direction, and The second diffraction section has a third length in the first direction, and The above first length and the above third length are different light guide devices. In paragraph 1, A light guide device in which the first length is greater than the third length. In paragraph 2, An optical guide device in which the first length is 2 to 14 times the third length. In paragraph 1, A light guide device in which at least one of the first diffraction part and the second diffraction part is a reflection-type diffraction element. In paragraph 4, The above-mentioned first diffraction part is a reflection-type diffraction element, and A light guide device in which the amount of light diffracted at the first diffraction section is 5% to 35% of the amount of light incident on the first diffraction section. In paragraph 4, The above-mentioned first diffraction part is a reflection-type diffraction element, and A light guide device in which the amount of light diffracted at the first diffraction section is 90% or more of the amount of light incident at the first diffraction section. In paragraph 6, A light guide device in which the first angle corresponding to half the angle of view in the first diffraction section and the second angle corresponding to half the angle of view in the second diffraction section correspond to the following [Equation 1]. [Mathematical Formula 1] In Paragraph 7, In the first direction, the center of the first diffraction section and the center of the second diffraction section are separated by a fourth length, and The above second length is a light guide device corresponding to the following [Equation 2]. [Mathematical Formula 2] As a light guide device placed between a display and an object, A plate portion positioned to face the above-mentioned display; A first diffraction section and a second diffraction section disposed on the above plate section; and It includes a control unit for adjusting the wavelength of the above display, and The first diffraction unit diffracts light incident on the plate unit to the second diffraction unit, and The second diffraction unit diffracts light reflected from within the plate unit to an external image sensor, and The first diffraction unit diffracts at least a portion of the light directed from the display toward the object, and The above control unit is a light guide device that differently adjusts the wavelength of the display in a first direction from the first diffraction unit toward the second diffraction unit. In paragraph 1, The above display has the first diffraction part and an overlap area in the direction from the object toward the display, and The above control unit is a light guide device that adjusts the wavelength within the overlap area differently.

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