Projection substrate and method for manufacturing projection substrate

Abstract

A projection substrate for transmitting at least a portion of light of a specific wavelength range incident from a first surface to a second surface on the opposite side of the first surface and projecting an image onto the second surface, the projection substrate comprising: a transparent glass plate provided on the first surface side; and a diffraction grating which is provided on the second surface side with respect to the glass plate and in which a plurality of grooves are formed by the resist so as to diffract and propagate light corresponding to the image, the thickness of the resist film between the bottom surface of the groove and the glass plate being determined on the basis of the wavelength of the light diffracted in the groove.

Description

Technical Field

[0001] The present invention relates to a projection substrate for projecting an image and a method for manufacturing the projection substrate. Background Art

[0002] In a head mounted display device, light output from an optical projector system propagates through a waveguide formed on a transparent substrate and is visually recognized by a user (for example, Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Publication No. 2021-509726 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In a head mounted display device, it is required to increase the viewing angle, which is a range in which the image can be viewed. In the display device described in Patent Document 1, there is a problem that uneven brightness occurs when the viewing angle is increased.

[0008] Therefore, the present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a projection substrate capable of suppressing the occurrence of uneven brightness in a head mounted display device.

[0009] Technical means of solving problems

[0010] A projection substrate according to a first embodiment of the present invention is used to transmit at least a portion of light in a specific wavelength range incident from a first surface to a second surface on the opposite side of the first surface, and to project an image onto the second surface. The projection substrate comprises: a glass plate, which is provided on the first surface side and is transparent; and a diffraction grating, which is provided on the second surface side relative to the glass plate and has a plurality of grooves formed by an anti-etching agent so that the light corresponding to the image is diffracted while propagating, and the thickness of the anti-etching agent film between the bottom surface of the groove and the glass plate is determined based on the wavelength of the light diffracted in the groove.

[0011] The thickness of the resist film between the bottom surface of the groove and the glass plate may be determined based on the depth of the groove and the pitch of the groove. The thickness of the resist film may be greater than 10 nanometers and less than 500 nanometers. The difference between the refractive index of the resist and the refractive index of the glass plate may be less than 0.4. The filling factor of the diffraction grating may be greater than 0.05 and less than 0.95.

[0012] It may also be a case where it has: a first diffraction grating that reflects the light incident from the first surface in a predetermined direction; a second diffraction grating that diffracts a portion of the light incident from the first diffraction grating; and a third diffraction grating that reflects at least a portion of the light incident from the second diffraction grating and projects the reflected light as image light, wherein the thickness of the resist film between the bottom surface of the groove of the second diffraction grating and the glass plate is determined based on the wavelength of the light diffracted in the groove.

[0013] The projection substrate may include a plurality of glass plates, the diffraction grating for diffracting the light in different wavelength ranges may be formed on each of the plurality of glass plates, and the thickness of each of the resist films corresponding to the plurality of glass plates may be determined based on the wavelength of the light diffracted by the diffraction grating formed on each of the glass plates. The diffraction grating corresponding to a first wavelength range may have a greater thickness of the resist film than the diffraction grating corresponding to a second wavelength range shorter than the first wavelength range.

[0014] The manufacturing method of the projection substrate of the second embodiment of the present invention is a manufacturing method of the projection substrate for projecting images, and the manufacturing method of the projection substrate has the following steps: coating a resist on a transparent glass plate; pressing a mold having a plurality of grooves formed therein onto the resist until a position determined based on the wavelength of light diffracted in the plurality of grooves; hardening the resist by ultraviolet rays or heat while the mold is pressed onto the resist; and removing the mold from the resist.

[0015] Effects of the Invention

[0016] According to the present invention, it is possible to suppress uneven brightness in a head mounted display device. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] [ Figure 1 ] represents a structural example of a glasses-type terminal according to this embodiment.

[0018] [ Figure 2 ] schematically shows the optical path of projection light in the glasses-type terminal of this embodiment.

[0019] [ Figure 3 ] schematically shows the optical path of the projection light in the projection substrate of this embodiment.

[0020] [ Figure 4 ] shows an example of projection light irradiated onto the projection substrate by the projection unit of the present embodiment and image light emitted by the projection substrate.

[0021] [ Figure 5] shows a structural example of a projection substrate according to this embodiment.

[0022] [ Figure 6 ] represents a structural example of the incident area 210 including a diffraction grating.

[0023] [ Figure 7 ] represents a structural example of the incident area 210 including a multi-order type diffraction grating.

[0024] [ Figure 8 ] represents a structural example of the incident area 210 including a tilted type diffraction grating.

[0025] [ Fig. 9 ] represents a structural example of the incident area 210 including a blazed type diffraction grating.

[0026] [ Fig.10 ] is a diagram for illustrating the thickness of the resist film.

[0027] [ Fig.11 ] is a diagram showing the simulation results of the brightness of the image formed by the pupil.

[0028] [ Fig.12 ] is a diagram showing the simulation results of the brightness of the image formed by the pupil.

[0029] [ Fig.13 ] is a diagram showing another example of the simulation result of the brightness of the image formed by the pupil.

[0030] [ Fig.14 ] represents a modified example of the glasses-type terminal of the present embodiment.

[0031] [ Fig.15 ] represents a method for manufacturing a projection substrate.

[0032] [ Fig.16 ] represents a method for manufacturing a projection substrate. DETAILED DESCRIPTION

[0033] <Configuration Example of Glasses-Type Terminal 10 >

[0034] Figure 1 The following is a structural example of the glasses-type terminal 10 of the present embodiment. In the present embodiment, three axes orthogonal to each other are set as the X-axis, the Y-axis, and the Z-axis. The glasses-type terminal 10 is a wearable device worn by a user. The glasses-type terminal 10 allows the user to view the scenery through the glasses, and projects image light corresponding to the image to a display area provided on the projection substrate 100. The glasses-type terminal 10 includes a projection substrate 100, a frame 110, and a projection unit 120.

[0035] The projection substrate 100 transmits at least a portion of light in a specific wavelength range incident from the first surface to the second surface, and projects an image onto the second surface. Here, the first surface of the projection substrate 100 is the surface facing the opposite side of the user when the user wears the glasses-type terminal 10. Moreover, the second surface of the projection substrate 100 is the surface facing the user when the user wears the glasses-type terminal 10. Figure 1 This shows an example in which the first surface and the second surface of the projection substrate 100 are arranged substantially parallel to the XY plane. The projection substrate 100 is, for example, a substrate in which a diffraction grating that functions as a waveguide is formed on a glass plate. The glass plate 112 is provided on the first surface side of the projection substrate. The diffraction grating is provided on the second surface side relative to the glass plate 112. In the diffraction grating, a plurality of grooves are formed by a resist. The grooves are formed so that light corresponding to an image is propagated while being diffracted. The projection substrate 100 will be described later.

[0036] The frame 110 fixes the projection substrate 100. The frame 110 is provided with the projection substrate 100 as at least one of a lens for the right eye and a lens for the left eye of the user. Figure 1 The example shown is that the frame 110 is provided with the projection substrate 100 a as a lens for the right eye of the user, and the projection substrate 100 b is provided as a lens for the left eye.

[0037] Alternatively, the frame 110 may be provided with a projection substrate 100 as a lens for the user's right eye or left eye. In addition, the frame 110 may be provided with a projection substrate 100 as a lens for both eyes of the user. In this case, the frame 110 may also have the shape of goggles. The frame 110 may have a temple, a strap, and the like so that the user can wear the glasses-type terminal 10.

[0038] The projection unit 120 is provided on the frame 110, and irradiates projection light for projecting image light onto the projection substrate 100 toward the projection substrate 100. The frame 110 is provided with one or more projection units 120. Figure 1 The example shown is that the frame 110 is provided with a projection unit 120 a for irradiating the projection substrate 100 a with the projection light L1 and a projection unit 120 b for irradiating the projection substrate 100 b with the projection light L2 .

[0039] The projection unit 120 may be provided at a portion of the frame 110 where the projection substrate 100 is fixed, or at a side support of the frame 110. Ideally, the projection unit 120 is provided in a manner that is integrated with the frame 110. The projection unit 120, for example, irradiates projection light having one wavelength onto the projection substrate 100 so that the user can view a monochrome image. Furthermore, the projection unit 120 may irradiate projection light having multiple wavelengths onto the projection substrate 100 so that the user can view an image having multiple colors.

[0040] Figure 2 The optical path of the projection light in the glasses-type terminal 10 of the present embodiment is schematically shown. The projection unit 120 irradiates the projection light to the incident area 210 provided on the projection substrate 100. The incident area 210 guides the projection light into the substrate of the projection substrate 100. And, the projection substrate 100 emits the projection light guided in the substrate from the emission area 230 as image light. In addition, the incident area 210 and the emission area 230 will be described later.

[0041] Figure 3 The schematic diagram of the optical path of the projection light in the projection substrate 100 of the present embodiment is shown. Although it will be described later, the projection substrate 100 has an incident area 210, a branch area 220, and an exit area 230. The projection light L is incident on the incident area 210, passes through the branch area 220, and is emitted from the exit area 230 as image light P. As the projection light L moves away from the incident area 210, the branch area 220 guides the projection light L to the exit area 230 part by part.

[0042] Similarly, as the projection light L moves away from the branching region 220 , the emission region 230 emits a portion of the projection light L as a portion of the image light P. Thus, the projection substrate 100 emits the projection light L incident on the incident region 210 as the image light P from the emission region 230 .

[0043] Here, consider the following example: the branch region 220 guides the projection light L to the emission region 230 at a certain ratio in the entire region of the branch region 220. At this time, as the projection light L moves away from the incident region 210, the light amount of the projection light L decreases, so the projection light L incident on the emission region 230 from the branch region 220 may have different intensities depending on the distance from the incident region 210.

[0044] Similarly, consider an example in which the emission area 230 emits the projection light L as the image light P at a certain ratio in the entire area of ​​the emission area 230. At this time, as the projection light L moves away from the branch area 220, the light amount of the projection light L decreases, so the image light P emitted from the emission area 230 sometimes has different intensities depending on the distance from the incident area 210 and the distance from the emission area 230. For example, sometimes the brightness of the upper left pixel of the image projected from the emission area 230 gradually decreases toward the lower right pixel. The projection substrate 100 of this embodiment reduces such brightness deviation.

[0045] <Example of projection light and image light>

[0046] Figure 4The figure shows an example of the projection light L irradiated to the projection substrate 100 by the projection unit 120 of the present embodiment and the image light P emitted by the projection substrate 100. The projection unit 120 irradiates the projection light L toward the second surface of the projection substrate 100 located in the +Z direction, for example. The projection light L corresponds to the image seen by the user. For example, when a screen is provided on a surface substantially parallel to the XY plane to project the projection light L, an image M1 for the user to watch is displayed on the screen. The image seen by the user is, for example, an augmented reality (AR) image or a virtual reality (VR) image produced by a processor of the projection unit 120. In this way, the projection unit 120 irradiates a plurality of light rays forming the image M1 on a surface substantially parallel to the XY plane as the projection light L.

[0047] In this embodiment, an example is described in which the projection unit 120 projects a substantially rectangular image M1 whose long side is in the X-axis direction onto a surface substantially parallel to the XY plane. Figure 4 , five of the multiple light rays irradiated by the projection unit 120 are represented as input light rays 20. For example, the light corresponding to the upper left pixel of the image is set as the first input light ray 20a, the light corresponding to the lower left pixel of the image is set as the second input light ray 20b, the light corresponding to the central pixel of the image is set as the third input light ray 20c, the light corresponding to the upper right pixel of the image is set as the fourth input light ray 20d, and the light corresponding to the lower right pixel of the image is set as the fifth input light ray 20e.

[0048] The projection unit 120 irradiates the projection light L to the incident area 210 of the projection substrate 100, for example, to form a positive virtual image at infinity or a predetermined position. The projection light incident on the incident area 210 is emitted from the emission area 230 as the image light P through the branch area 220. The image light P is emitted from the emission area 230 and is incident on the eye of the user separated from the projection substrate 100 by a distance d. And, the image light P is imaged as an image M2 on the retina of the eye of the user. In this way, the image light P includes a plurality of light beams imaged as the image M2.

[0049] Figure 4 , five of the plurality of light beams irradiated from the circular area C of the emission area 230 of the projection substrate 100 and imaged at a predetermined position are represented as output light beams 30. For example, the light beam imaged as the lower right pixel of the image is set as the first output light beam 30a, the light beam imaged as the upper right pixel of the image is set as the second output light beam 30b, the light beam imaged as the central pixel of the image is set as the third output light beam 30c, the light beam imaged as the lower left pixel of the image is set as the fourth output light beam 30d, and the light beam imaged as the upper left pixel of the image is set as the fifth output light beam 30e.

[0050] Each light beam corresponds to a plurality of input light beams 20 incident from the projection unit 120. For example, the first output light beam 30a corresponds to the first input light beam 20a, and the first input light beam 20a includes a plurality of light beams generated by multiple branches and multiple diffractions between the incident area 210 and the exit area 230 of the projection substrate 100. Similarly, the second output light beam 30b corresponds to the second input light beam 20b, the third output light beam 30c corresponds to the third input light beam 20c, the fourth output light beam 30d corresponds to the fourth input light beam 20d, and the fifth output light beam 30e corresponds to the fifth input light beam 20e.

[0051] In other words, the image M2 formed on the retina of the user's eye by the image light P emitted from the emission area 230 corresponds to the image M1 projected by the projection light L irradiated by the projection unit 120. Thus, the user wearing the eyeglass-type terminal 10 can feel that the image M2 is superimposed on the scenery seen through the projection substrate 100 and projected on the second surface of the projection substrate 100. In other words, the emission area 230 functions as a display area for displaying the image M2 corresponding to the image M1 projected by the projection light L.

[0052] Figure 4 , the image M2 observed by the user is an example of an image in which the image M1 projected by the projection light L is reversed vertically and horizontally. In addition, the image M1 projected by the projection light L may be a static image or a dynamic image instead. Next, the projection substrate 100 that emits the image light P corresponding to the incident projection light L as described above is described.

[0053] <Configuration Example of Projection Substrate 100>

[0054] Figure 5 A configuration example of the projection substrate 100 according to the present embodiment is shown. Figure 5 The first surface and the second surface of the projection substrate 100 are arranged substantially parallel to the XY plane. The projection substrate 100 is a substrate for transmitting at least a portion of the light incident from the first surface to the second surface on the opposite side of the first surface, and projecting image light onto the second surface. As an example, the projection substrate 100 is a glass plate. The projection substrate 100 includes an incident area 210, a branch area 220, and an emission area 230.

[0055] <Example of incident area 210>

[0056] The incident region 210 receives projection light for projecting image light, and guides the incident projection light toward the branch region 220 . Figure 5The incident region 210 is shown as an example having a circular shape on a surface substantially parallel to the XY plane, but the invention is not limited thereto. The incident region 210 may have an elliptical, polygonal, trapezoidal, or other shape as long as it can guide the projection light to the branching region 220 .

[0057] The incident region 210 has a diffraction grating having a plurality of first grooves 212 formed at a first period. In other words, the plurality of first grooves 212 are arranged on the upper surface of the projection substrate 100 in the same direction with a predetermined groove width and interval, thereby functioning as a diffraction grating. The incident region 210 has a reflective or transmissive diffraction grating. The diffraction grating (equivalent to the first diffraction grating) of the incident region 210 transmits or reflects the projection light incident from the first surface in a predetermined direction. For example, the diffraction grating of the incident region 210 guides the projection light in the direction of the branch region 220 by reflective diffraction or transmissive diffraction.

[0058] The first period of the plurality of first grooves 212 is, for example, in the range of about 10 nm to about 10 μm. The first period is preferably in the range of about 100 nm to about 1 μm. The first period is more preferably in the range of about 200 nm to about 800 nm. The depth of the plurality of first grooves 212 is in the range of about 1 nm to about 10 μm. The depth of the plurality of first grooves 212 is preferably in the range of about 50 nm to about 800 nm.

[0059] The filling factor of the plurality of first grooves 212 is preferably in the range of 0.05 or more and 0.95 or less. Here, the filling factor is the value obtained by dividing the distance between two adjacent first grooves 212 by the first period. In addition, sometimes the distance between two adjacent first grooves 212 is referred to as a line, the width of the first groove 212 is referred to as a space, and the first period is referred to as a pitch. In this case, the pitch is the sum of the line and the space, and the filling factor is the value obtained by dividing the line by the pitch.

[0060] The plurality of first grooves 212 are arranged, for example, in a direction from the incident region 210 toward the branch region 220. Here, the traveling direction of the projection light from the incident region 210 toward the branch region 220 is referred to as a first direction. Figure 5 The following example is shown, that is, the first direction is a direction substantially parallel to the X-axis direction, and the first grooves 212 extending in a direction substantially parallel to the Y-axis direction are arranged along the first direction. The projection light is converged and incident on the incident area 210, so the incident area 210 guides the projection light to the branch area 220 in a manner having a spread angle with the first direction as the center within the plane of the projection substrate 100.

[0061] <Example of branch area 220>

[0062] The branch region 220 guides a portion of the projection light incident from the incident region 210 toward the exit region 230. The branch region 220 is a region provided on a surface substantially parallel to the XY plane where the projection light passes. The branch region 220 has a reflective diffraction grating. The diffraction grating (equivalent to the second diffraction grating) of the branch region 220 diffracts a portion of the projection light incident from the diffraction grating of the incident region 210. The diffraction grating of the branch region 220 guides the projection light in the direction of the exit region 230 by reflective diffraction. The branch region 220 has, for example, a rectangular shape with the first direction being the long side direction.

[0063] In addition, since the projection light travels while expanding with the first direction as the center, the branch region 220 preferably has a shape that expands as it passes through the incident region 210 and moves away from the first direction, which is the direction in which the projection light travels, as it moves away from the incident region 210. For example, the branch region 220 has a shape such as a trapezoid or a fan on a surface that is substantially parallel to the XY plane. Figure 5 The example in which the branch region 220 has a trapezoidal shape is shown. The branch region 220 of such a shape can be formed corresponding to the region where the projection light travels while spreading on the XY plane, so that the projection light can be efficiently guided.

[0064] The branch region 220 has a diffraction grating having a plurality of second grooves 222 formed at a second period. In other words, the plurality of second grooves 222 are arranged in the same direction on the upper surface of the projection substrate 100 at a predetermined groove width and interval.

[0065] The second period of the plurality of second grooves 222 is a period different from the first period of the plurality of first grooves 212. Ideally, in order to guide the projection light to the emission area 230, the second period is selected to be an appropriate period. The second period is, for example, in the range of about 10 nm to about 10 μm. The second period is preferably in the range of about 50 nm to about 1 μm. The second period is more preferably in the range of about 100 nm to about 700 nm. The depth of the plurality of second grooves 222 is in the range of about 1 nm to about 10 μm. The depth of the plurality of second grooves 222 is preferably in the range of about 5 nm to about 800 nm.

[0066] The plurality of second grooves 222 are arranged, for example, along a predetermined direction. For example, the direction from the branch region 220 toward the emission region 230 is set as the second direction, and the angle formed by the first direction and the second direction is set as the first angle. In this case, the plurality of second grooves 222 are formed along a direction that is inclined toward the second direction at an angle of 1 / 2 of the first angle relative to the first direction. Figure 5The following example is shown, that is, the second direction is a direction substantially parallel to the Y-axis direction, the first angle is substantially 90 degrees, and the plurality of second grooves 222 are arranged in a direction inclined substantially 45 degrees toward the second direction relative to the first direction.

[0067] The branch region 220 has a plurality of first segmented regions 224 arranged along the traveling direction of the incident projection light. The depths of the second grooves 222 formed in the plurality of first segmented regions 224 are different. In other words, in the branch region 220, the second grooves 222 are formed in such a manner that the proportion of the light guided to the emission region 230 in the input projection light is different for each first segmented region 224.

[0068] It is desirable that the branch region 220 has three or more first division regions 224. The second periods of the plurality of second grooves 222 respectively formed in the plurality of first division regions 224 are all the same, for example. In this way, the branch region 220 is divided into the plurality of first division regions 224, and the light amount of the projection light guided to the exit region 230 is made different for each first division region 224, so that the projection light having different intensities depending on the distance from the incident region 210 is guided to the exit region 230, and the light amount distribution in the direction perpendicular to the traveling direction of the projection light is adjusted to be substantially constant.

[0069] For example, the second groove 222 is formed in such a manner that the depth of the second groove 222 provided in one first divided region 224 is greater than the depth of the second groove 222 provided in a first divided region 224 closer to the incident region 210 than the first divided region 224. In this case, the rate of change in the depth of the second groove 222 of two adjacent first divided regions 224 among the plurality of first divided regions 224 may be greater as the distance from the incident region 210 increases.

[0070] As an example, Figure 5 As shown in FIG. 1 , a branch region 220 having three first segmented regions 224 is considered. The diffraction grating of the branch region is arranged in the first segmented region 224a, the first segmented region 224b whose distance from the diffraction grating of the incident region 210 is larger than that of the first segmented region 224a, and the first segmented region 224c whose distance from the diffraction grating of the incident region 210 is larger than that of the first segmented region 224b. Here, the first segmented region 224a closest to the incident region 210 among the three first segmented regions 224 is set such that the depth of the second groove portion 222a is formed so that approximately 1 / 4 of the light amount of the incident projection light is guided to the exit region 230. At this time, the remaining approximately 3 / 4 of the light amount of the projection light incident on the first segmented region 224a closest to the incident region 210 is incident on the adjacent first segmented region 224b.

[0071] The first segmented region 224b is configured such that the depth of the second groove portion 222b is formed so as to guide approximately 1 / 3 of the light amount of the incident projection light to the exit region 230. In other words, the depth of the second groove portion 222b of the first segmented region 224b that is second closest to the incident region 210 is formed to be greater than the depth of the second groove portion 222a so as to guide 4 / 3 times the light amount of the first segmented region 224a that is closest to the incident region 210 to the exit region 230. Such first segmented region 224b guides approximately 1 / 4 of the light amount of the projection light incident on the first segmented region 224a that is closest to the incident region 210 to the exit region 230.

[0072] Furthermore, the remaining approximately 1 / 2 of the projection light incident on the first segmented area 224a closest to the incident area 210 is incident on the adjacent first segmented area 224c. The first segmented area 224c third closest to the incident area 210 is configured such that the depth of the second groove portion 222c is formed so as to guide approximately 1 / 2 of the incident projection light to the exit area 230. In other words, the depth of the second groove portion 222c of the first segmented area 224c third closest to the incident area 210 is formed to be greater than the depth of the second groove portion 222b so as to guide 3 / 2 times the light of the first segmented area 224b second closest to the incident area 210 to the exit area 230.

[0073] Furthermore, the rate of change of the depth of the second groove portion 222 of two adjacent first divided regions 224 among the three first divided regions 224 is formed so as to be larger as being farther from the incident region 210. Furthermore, the first divided region 224c, which is the third closest to the incident region 210, guides approximately 1 / 4 of the amount of the projection light incident on the first divided region 224a closest to the incident region 210 to the exit region 230. As can be seen from the above example, the branch region 220 sets the amount of the projection light guided to the exit region 230 to a predetermined value differently for each first divided region 224, thereby making it possible to set the amount of the projection light guided to the exit region 230 corresponding to each first divided region 224 to a substantially fixed distribution and guide the projection light to the exit region 230.

[0074] In addition, the branch region 220 may further include a first reflection region 226 as one of the first division regions 224 at a position farthest from the incident region 210 . Figure 5 The example in which the branch region 220 includes three first segmented regions 224 and a first reflection region 226 is shown. The first reflection region 226 reflects at least a portion of light that has passed through the plurality of first segmented regions 224 again toward the plurality of first segmented regions 224. The first reflection region 226 includes a second groove portion 222 having a depth greater than that of the second groove portion 222 of the adjacent first segmented region 224.

[0075] For example, it is desirable that the depth of the second groove 222 of the first reflection region 226 is approximately three times or more the maximum depth of the second grooves 222 of the plurality of first segmented regions 224. More preferably, the depth of the second groove 222 of the first reflection region 226 is approximately ten times or more the maximum depth of the second groove 222 of the plurality of first segmented regions 224. In addition, the second grooves 222 of the first reflection region 226 may also be arranged along the first direction.

[0076] Since the branch region 220 has such a first reflection region 226, the plurality of first division regions 224 guide at least a portion of the light reflected by the first reflection region 226 to the emission region 230. Thus, the branch region 220 can guide more projection light to the emission region 230. In addition, the depth of the second groove portion 222 of the plurality of first division regions 224 can also be determined so that each first division region 224 includes the reflected light formed by the first reflection region 226 and the light amount of the projection light guided to the emission region 230 is substantially constant.

[0077] <Example of a cross-sectional view of the incident region 210>

[0078] Figure 6 The structure example of the incident area 210 including the diffraction grating is shown. The incident area 210 includes a transparent substrate 214, a resin layer 216, and a reflective layer 218. The transparent substrate 214 is formed of a material that transmits the projection light L1. The transparent substrate 214 is formed of, for example, glass or plastic. The transparent substrate 214 of the present embodiment is formed of glass having a thickness of 0.4 mm. In addition, an anti-reflection coating may be provided on the surface of the transparent substrate 214 on the opposite side to the resin layer 216. The anti-reflection coating is formed of, for example, magnesium fluoride, sapphire or silicon dioxide. By doing so, the reflection on the surface of the transparent substrate 214 on the opposite side to the resin layer 216 can be reduced.

[0079] The resin layer 216 is formed of, for example, a resin or a resist. The resin layer 216 is formed, for example, in a range of 10 nm or more and less than 500 nm. The resin layer 216 is preferably in a range of 30 nm or more and less than 200 nm.

[0080] The resin layer 216 includes a plurality of first grooves 212 as concave-convex portions. The plurality of first grooves 212 are repeatedly formed at a first period in a direction of guiding the projection light L1 to the branch region 220. Figure 6As shown, the first groove portion 212 is a binary type diffraction grating including a concave portion 212a and a convex portion 212b. In other words, a plurality of first groove portions 212 are arranged on the upper surface of the projection substrate 100 in the same direction with a predetermined groove width and interval, thereby functioning as a diffraction grating. The diffraction grating of the incident area 210 is a reflective diffraction grating. The diffraction grating of the incident area 210 guides the projection light Lr to the direction of the branch area 220 by reflective diffraction.

[0081] The plurality of first grooves 212 may be configured in a step-like shape. In other words, the first grooves 212 formed in a step-like shape are a multi-step type diffraction grating. Figure 7 A structural example of the incident region 210 including a multi-order type diffraction grating is shown.

[0082] The plurality of first grooves 212 may be configured to be inclined in the direction of guiding the projection light L1 to the branch region 220. In other words, the first grooves 212 configured to be inclined in the direction of guiding the projection light L1 to the branch region 220 are inclined type diffraction gratings (also referred to as bracket type diffraction gratings). Figure 8 A configuration example of the incident region 210 including a tilt-type diffraction grating is shown.

[0083] The plurality of first grooves 212 may be configured in a sawtooth shape. In other words, the first grooves 212 configured in a sawtooth shape are blazed-type diffraction gratings (also referred to as ruled-line diffraction gratings). Fig. 9 A structural example of the incident region 210 including a blazed type diffraction grating is shown.

[0084] The reflective layer 218 reflects the projection light L1 that transmits the transparent substrate 214 and the resin layer 216. The reflective layer 218 is formed on the surface of the diffraction grating including the plurality of first grooves 212 on the opposite side of the transparent substrate 214. The reflective layer 218 is formed of, for example, a metal. Specifically, the reflective layer 218 is formed of at least one of aluminum, silver, tantalum oxide, or nickel oxide. The reflective layer 218 is formed of, for example, aluminum having a thickness of about 10 nm to about 200 nm. The reflective layer 218 is preferably formed in a range of about 50 nm to about 150 nm. The reflective layer 218 of this embodiment is formed of aluminum having a thickness of 100 nm.

[0085] The reflective layer 218 is formed to cover the surface of the resin layer 216 on the opposite side from the transparent substrate 214. Figure 6 As shown in the binary type diffraction grating, the thickness of the reflective layer 218 is formed to be constant. Figure 7 As in the multi-step type shown in FIG. 1 , the surface of the reflective layer 218 is formed to be flat.

[0086] <Example of resist film thickness>

[0087] Fig.10 2 is a diagram for explaining the thickness of the resist film. A plurality of second grooves 222 are formed on the glass plate 112. Line 240 is the width of the convex portion 223a of the second groove 222. Space 242 is the width of the first concave portion 223b of the second groove 222. Pitch 244 is the sum of line 240 and space 242, and is the length of the second period. The first fill factor is the value obtained by dividing line 240 by pitch 244.

[0088] As an example, the thickness 248 of the resist film between the bottom surface of the second groove portion 222 and the glass plate 112 is greater than or equal to 10 nanometers and less than 500 nanometers. The thickness 248 of the resist film is determined by the wavelength of the light diffracted in the second groove portion 222. More specifically, the thickness 248 of the resist film for diffracting green light (wavelength of 490 nanometers to 550 nanometers) is determined to be greater than the thickness 248 of the resist film for diffracting blue light (wavelength of 430 nanometers to 490 nanometers).

[0089] The thickness 248 of the resist film between the bottom surface of the second groove 222 and the glass plate 112 is determined based on the depth 222 of the second groove and the pitch 244 of the second groove 222. In the example of this specification, the thickness 248 of the resist film when the pitch is 260 nanometers is 30 nanometers or more and less than 200 nanometers. At this time, the thickness 248 of the resist film is preferably set to be 20 times or less than the depth 246 of the second groove 222.

[0090] Fig.11 as well as Fig.12 : is a diagram showing the simulation result of the brightness of the image formed by the pupil. Fig.11 The vertical axis and horizontal axis represent the X coordinate and Y coordinate of the pixel respectively. Fig.11 as well as Fig.12 The results of simulating the brightness of the image under multiple conditions with different thicknesses 248 of the resist film between the bottom surface of the groove and the glass plate 112 in the incident region 210 are shown. The brightness of the image was also simulated under the same conditions in the branch region 220 and the emission region 230, and the results showed the same results.

[0091] Fig.11 (a) shows the simulation result of the brightness of the image when the thickness 248 of the resist film is 50 nanometers. Fig.11 (b) shows the simulation result of the brightness of the image when the thickness 248 of the resist film is 100 nanometers. Fig.12 (a) shows the simulation result of the brightness of the image when the thickness 248 of the resist film is 150 nanometers. Fig.12(b) shows the simulation result of the brightness of the image when the thickness 248 of the resist film is 200 nanometers. The black area in the figure shows the range where the brightness unevenness occurs.

[0092] When the thickness of the resist film 248 is reduced from 50 nm ( Fig.11 (a)) increases to 100 nm ( Fig.11 (b)) Fig.11 The black area in the center of (a) indicating uneven brightness becomes smaller. When the thickness of the resist film 248 is reduced from 100 nm ( Fig.11 (b)) increases to 150 nm ( Fig.12 (a)) Fig.11 The black area indicating uneven brightness generated in the center of (b) becomes smaller. On the other hand, when the thickness of the resist film 248 is reduced from 150 nm ( Fig.12 (a)) increases to 200 nm ( Fig.12 (b)), the overall brightness of the image decreases. Fig.11 as well as Fig.12 The simulation results show that when the thickness 248 of the resist film in the projection substrate 100 is within an appropriate range, the brightness unevenness can be suppressed when the viewing angle of the glasses-type terminal 10 is relatively large.

[0093] Fig.13 FIG. 2 is a diagram showing another example of the simulation result of the brightness of the image formed by the pupil. Fig.13 The vertical axis and horizontal axis represent the X coordinate and Y coordinate of the pixel respectively. Fig.13 The results of simulating the brightness of the image under multiple conditions with different thicknesses 248 of the resist film between the bottom surface of the groove and the glass plate 112 in the incident region 210 are shown. The brightness of the image was also simulated under the same conditions in the branch region 220 and the emission region 230, and the results showed the same results.

[0094] Fig.13 (a) is a simulation result of the brightness of an image when the thickness 248 of the resist film is 100 nanometers. Fig.13 (b) is a simulation result of the brightness of an image when the thickness 248 of the resist film is 150 nanometers. Fig.13 (c) is a simulation result of the brightness of an image when the thickness 248 of the resist film is 200 nanometers.

[0095] Fig.13 The dark part of the image shows that the brightness is low. Fig.13 (a) shows an increase from 100 nm to 150 nm ( Fig.13 (b)) Fig.13The black area indicating uneven brightness in the lower right corner of (a) becomes smaller. Fig.13 (b) shows an increase from 150 nm to 200 nm ( Fig.13 (c)) Fig.13 The black areas indicating uneven brightness generated at the lower right and lower left of (b) become smaller. Fig.13 The simulation results show that the larger the thickness 248 of the resist film, the lower the brightness deviation of the entire image and the more constant the brightness. On the other hand, if the thickness 248 of the resist film is too large, the overall brightness becomes smaller or uneven brightness occurs. Therefore, in the projection substrate 100, by making the thickness 248 of the resist film a value within an appropriate range, uneven brightness can be suppressed when the viewing angle of the eyeglass-type terminal 10 is relatively large.

[0096] Furthermore, when the difference between the refractive index of the resist and the refractive index of the glass plate is small, it is easy to suppress uneven brightness. For example, the difference between the refractive index of the resist and the refractive index of the glass plate is preferably 0.4 or less. As an example, the refractive index of the glass plate is 2.1. The refractive index of the resist is 1.9.

[0097] <Example of emission region 230>

[0098] Figure 5 The emission region 230 guides at least a portion of the projection light incident from the branch region 220 and emits the projection light from the second surface of the projection substrate 100 as image light. Figure 5 The following example is shown, that is, the emission area 230 has a rectangular shape with the X-axis direction as the long side direction on a surface substantially parallel to the XY plane, but the present invention is not limited thereto. The emission area 230 can be any shape as long as it can guide the projection light and emit it as image light, for example, it can have a rectangular, square, trapezoidal, etc. with the Y-axis direction as the long side direction.

[0099] The exit region 230 has a diffraction grating having a plurality of third grooves 232 formed at a third period. In other words, the plurality of third grooves 232 are arranged on the upper surface of the projection substrate 100 in the same direction with a predetermined groove width and interval, thereby functioning as a diffraction grating. The exit region 230 has a reflective or transmissive diffraction grating. The diffraction grating (equivalent to the third diffraction grating) of the exit region 230 reflects or transmits at least a portion of the light incident from the diffraction grating of the branch region 220. The diffraction grating of the exit region 230 projects the reflected or transmitted light as image light. The diffraction grating of the exit region 230 guides the image light in the direction of the user's eyes by reflective diffraction or transmissive diffraction.

[0100] The third period of the plurality of third grooves 232 provided in the emission region 230 is a period different from the second period of the plurality of second grooves 222 in the branch region 220. The third period of the plurality of third grooves 232 in the emission region 230 may also be the same period as the first period of the plurality of first grooves 212 in the incident region 210. In this way, by making the periods of the diffraction gratings provided in the region where the projection light is incident and the region where the image light is emitted consistent, the deformation of the image viewed by the user can be reduced.

[0101] The third period is formed, for example, in a range of about 10 nm to about 10 μm. The third period is preferably formed in a range of about 100 nm to about 1 μm. The third period is more preferably formed in a range of about 200 nm to about 800 nm. The depth of the plurality of third grooves 232 is formed in a range of about 1 nm to about 10 μm. The depth of the plurality of third grooves 232 is preferably formed in a range of about 5 nm to about 800 nm.

[0102] The plurality of third grooves 232 are arranged, for example, along the second direction from the branch region 220 toward the emission region 230 . Figure 5 An example is shown in which the third groove portions 232 extending in the first direction are arranged in the second direction.

[0103] The emission region 230 has a plurality of second divided regions 234 arranged along the traveling direction of the projection light incident from the branch region 220, similarly to the branch region 220. The depths of the third grooves 232 formed in the plurality of second divided regions 234 are different. In other words, in the emission region 230, the third grooves 232 are formed so that the proportion of light emitted as image light in the input projection light is different for each second divided region 234.

[0104] It is desirable that the emission region 230 has two or more second divided regions 234. For example, the depth of the third groove 232 provided in one second divided region 234 is formed to be greater than the depth of the third groove 232 provided in the second divided region 234 closer to the branch region 220 than the one second divided region 234. Moreover, in the case where the emission region 230 has three or more second divided regions 234, the further away from the branch region 220, the greater the change rate of the depth of the third groove 232 of two adjacent second divided regions 234. In addition, the third periods of the third grooves 232 are all the same, for example.

[0105] As described above, the emission area 230 is divided into a plurality of second divided areas 234, so that the light amount of light emitted as image light is different for each second divided area 234. Thus, the emission area 230 can guide the projection light as image light, similarly to the plurality of first divided areas 224 of the branch area 220, and when the observer observes the image light as an image, the light amount distribution of the entire image can be adjusted to be approximately constant.

[0106] The emission region 230 may further include a second reflection region 236 as one of the second divided regions 224 at a position farthest from the branch region 220 . Figure 5 The example in which the emission region 230 includes two second divided regions 234 and a second reflection region 236 is shown. The second reflection region 236 reflects at least a portion of the light that has passed through the plurality of second divided regions 234 again toward the plurality of second divided regions 234. The second reflection region 236 includes a third groove portion 232 having a depth greater than that of the third groove portion 232 of the adjacent second divided region 234.

[0107] For example, it is desirable that the depth of the third groove 232 of the second reflection region 236 is approximately three times or more the maximum depth of the third grooves 232 of the plurality of second segmented regions 234. More preferably, the depth of the third groove 232 of the second reflection region 236 is approximately ten times or more the maximum depth of the third grooves 232 of the plurality of second segmented regions 234.

[0108] Since the emission region 230 has such a second reflection region 236, the plurality of second divided regions 234 emit at least a portion of the light reflected by the second reflection region 236 from the second surface of the projection substrate 100 as image light. Thus, the emission region 230 can emit more projection light as image light, similar to the branch region 220. In addition, the depth of the third groove portion 232 of the plurality of second divided regions 234 can also be determined so that each second divided region 234 includes the reflected light formed by the second reflection region 236 and the light amount of the light emitted as image light is substantially constant.

[0109] As described above, the projection substrate 100 of the present embodiment branches the projection light incident on the incident area 210 at different ratios corresponding to each of the plurality of first divided areas 224 of the branch area 220, and emits the projection light as image light from the emission area 230. Thus, the projection substrate 100 can reduce the deviation in the brightness of the projected image viewed by the user. Moreover, the projection substrate 100 also emits the image light at different ratios corresponding to each of the plurality of second divided areas 234 in the emission area 230, thereby further reducing the deviation in the brightness of the image.

[0110] Such a projection substrate 100 can be realized by forming a diffraction grating corresponding to the incident area 210, the branch area 220, and the exit area 230 on the first surface or the second surface of a glass substrate or the like. In addition, the groove portion forming the diffraction grating is, for example, a resist, a resin, etc. Therefore, the projection substrate 100 of this embodiment is a substrate as described below, that is, it is not necessary to install a complex optical system, and can be simply produced by forming a groove portion with a predetermined period and depth in each area.

[0111] The widths of the convex and concave portions of the plurality of second divided regions 234 are formed so that the second filling factor becomes a predetermined value. The second filling factor is the ratio of the width of the convex portion in the second direction to the third period of the third groove portion 232. The second filling factor is, for example, 0.05 or more and 0.95 or less.

[0112] <Another example of glasses-type terminal 10>

[0113] The example of the following glasses-type terminal 10 has been described, that is, the above-mentioned projection substrate 100 is set on the frame 110, and the projection unit 120 irradiates the projection light to the incident area 210 of the projection substrate 100, but it is not limited to this. For example, a plurality of projection substrates 100 may be fixed to the frame 110 of the glasses-type terminal 10. Next, this glasses-type terminal 10 is described.

[0114] Fig.14 FIG. 1 shows a modified example of the glasses-type terminal 10 of the present embodiment. In the glasses-type terminal 10 of the modified example, Figure 1 The same reference numerals are used for the operations that are substantially the same as the operations of the glasses-type terminal 10 of the present embodiment, and the description thereof is omitted. Figure 1 The glasses-type terminal 10 shown has an almost unchanged appearance.

[0115] A plurality of glass plates 112 are fixed to the frame 110 of the glasses-type terminal 10 of the modified example. The plurality of glass plates 112 are fixed to the frame 110 so that the emission regions 230 provided on the plurality of glass plates 112 at least partially overlap when viewed from above substantially parallel to the XY plane. Fig.14 The following example is shown, that is, three glass plates 112R, 112G, and 112B are fixed to the frame 110 of the glasses-type terminal 10, and the emission areas 230R, 230G, and 230B of the three projection substrates 100 overlap when viewed from above on the XY plane.

[0116] Diffraction gratings for diffracting light of different wavelength ranges are formed on each of the plurality of glass plates 112R, 112G, and 112B. The projection unit 120 irradiates projection lights of different wavelengths to the incident regions 210 provided on each of the plurality of glass plates 112. The emission regions 230 provided on the plurality of glass plates 112 emit image lights corresponding to the projection lights irradiated from the projection unit 120 to the plurality of incident regions 210 from the second surfaces of the plurality of projection substrates 100 to the eyes of the user.

[0117] A user wearing such a glasses-type terminal 10 can view an image in which image lights of different wavelengths overlap each other, and thus can view an image having mixed colors. Fig.14 The following example is shown, that is, the projection unit 120 irradiates three projection lights corresponding to the first wavelength range, the second wavelength range, and the third wavelength range that form an image to the incident area 210 of the three projection substrates 100 respectively. The first wavelength range corresponds to red light (580 nanometers to 700 nanometers), for example. The second wavelength range corresponds to green light (480 nanometers to 580 nanometers), for example. The third wavelength range corresponds to blue light (400 nanometers to 480 nanometers), for example. The three projection substrates 100 overlap a plurality of image lights corresponding to a plurality of colors and emit them to the user's eyes. Thus, the user can, for example, watch an image with a plurality of colors.

[0118] As described above, by setting the thickness of the resist film between the bottom surface of the groove portion of the diffraction grating and the glass plate to a value within an appropriate range, uneven brightness can be suppressed. Fig.14 In the example of , the thickness of the resist film corresponding to the plurality of glass plates 112 is determined based on the wavelength of light diffracted in the diffraction grating formed on each glass plate 112. For example, the thickness of the resist film of the diffraction grating that diffracts light corresponding to the first wavelength range is determined to be greater than the thickness of the resist film of the diffraction grating that diffracts light corresponding to the second wavelength range. The thickness of the resist film when diffracting light corresponding to the second wavelength range is determined to be greater than the thickness of the resist film when diffracting light corresponding to the third wavelength range.

[0119] [Method of Manufacturing Projection Substrate 100]

[0120] A method for manufacturing the projection substrate 100 of this embodiment will be described. Fig.15 (a) to Fig.15 (c) and Fig.16 (a) to Fig.16 (c) shows a method for manufacturing the projection substrate 100 . Fig.15 (a) shows an original mold 400 for manufacturing the projection substrate 100. Fig.15 (b) shows a state where the mold of the projection substrate 100 is hardened. Fig.15(c) shows a state where the mold of the projection substrate 100 is removed from the original 400 .

[0121] Fig.15 (a) shows a cross section of an original mold 400 for manufacturing the projection substrate 100. Fig.15 In (a), the concave portion formed on the cross section of the original 400 represents a groove. The original 400 is coated with a stamp material 500. Fig.15 As shown in (b), the stamp material 500 applied on the original 400 is hardened. The hardened stamp material 500 has a certain degree of elasticity and can be used as a mold for manufacturing the projection substrate 100. Fig.15 As shown by the dotted arrow in (c), the mold of the hardened impression material 500 is removed from the original 400. A plurality of grooves are formed in the mold.

[0122] Fig.16 (a) shows a state where the stamp material 500 is pressed onto the resist 600 . Fig.16 (b) shows the state where the resist 600 is cured. Fig.16 (c) shows the state where the stamp material 500 is removed from the hardened resist 600. Fig.16 Before the step (a), a resist 600 is pre-coated on the transparent glass plate 112. Fig.16 As shown by the dotted arrow in (a), the mold of the stamp material 500 is pressed onto the resist 600 to a predetermined position. The predetermined position is determined based on the wavelength of light diffracted by the plurality of grooves of the resist 600 formed by pressing the mold, for example.

[0123] like Fig.16 As shown in (b), the resist 600 is hardened by ultraviolet rays while the mold of the stamp material 500 is pressed onto the resist 600. The resist 600 may be hardened by heat instead of ultraviolet rays. Then, the mold of the stamp material 500 is removed from the resist 600. In this way, the hardened resist 600 can be used as the incident region 210, the branch region 220, or the exit region 230.

[0124] In this embodiment, an example is described in which the first filling factor of the second groove portion 222 or the second filling factor of the third groove portion 232 is a value greater than or equal to 0.05 and less than or equal to 0.95. Similar to the filling factors of the second groove portion 222 and the third groove portion 232, the filling factor of the first groove portion 212 may also be a value greater than or equal to 0.05 and less than or equal to 0.95.

[0125] In the present embodiment, an example is described in which the thickness 248 of the resist film between the bottom surface of the second groove portion 222 and the glass plate 112 is greater than or equal to 10 nanometers and less than 500 nanometers. Similar to the thickness 248 of the resist film of the second groove portion 222, the thickness of the resist film between the bottom surface of the first groove portion 212 and the glass plate 112 may also be greater than or equal to 10 nanometers and less than 500 nanometers. Similarly, the thickness of the resist film between the bottom surface of the third groove portion 232 and the glass plate 112 may also be greater than or equal to 10 nanometers and less than 500 nanometers.

[0126] The present invention has been described above using the embodiments, but the technical scope of the present invention is not limited to the scope described in the embodiments, and various deformations and changes can be made within the scope of its main purpose. For example, all or part of the device can be functionally or physically dispersed / integrated in any unit. Moreover, new embodiments generated by any combination of multiple embodiments are also included in the embodiments of the present invention. The effects of the new embodiments generated by the combination have the effects of the original embodiments.

[0127] Explanation of symbols

[0128] 10: Glasses-type terminal

[0129] 20: Input light

[0130] 20a: First input ray

[0131] 20b: Second input ray

[0132] 20c: Third input ray

[0133] 20d: Fourth input ray

[0134] 20e: Fifth input ray

[0135] 30: Output light beam

[0136] 30a: First output light beam

[0137] 30b: Second output light beam

[0138] 30c: Third output light beam

[0139] 30d: Fourth output light beam

[0140] 30e: Fifth output light beam

[0141] 100: Projection substrate

[0142] 100a: Projection substrate

[0143] 100b: Projection substrate

[0144] 110: Framework

[0145] 112: Glass Plate

[0146] 112B: Glass Plate

[0147] 112G: Glass Plate

[0148] 112R: Glass Plate

[0149] 120: Projection Department

[0150] 120a: Projection Department

[0151] 120b: Projection Department

[0152] 210: Incident area

[0153] 212: First groove

[0154] 220: Branch area

[0155] 222: Second groove

[0156] 222a: Second groove

[0157] 222b: Second groove

[0158] 222c: Second groove

[0159] 223a: convex part

[0160] 223b: First recess

[0161] 224: First segmentation area

[0162] 224a: First segmented area

[0163] 224b: First segmented area

[0164] 224c: First segmented area

[0165] 226: First reflection area

[0166] 230: Emission area

[0167] 230B: Exit area

[0168] 230G: Emission area

[0169] 230R: Exit area

[0170] 232: Third slot

[0171] 234: Second segment area

[0172] 236: Second reflection area

[0173] 240: Line

[0174] 242: Space

[0175] 244: Spacing

[0176] 400: Original

[0177] 500: Impression material

[0178] 600: Resist

Claims

1. A projection substrate for transmitting at least a portion of light in a specific wavelength range incident from a first surface to a second surface opposite to the first surface, and projecting an image onto the second surface, the projection substrate comprising: a glass plate, disposed on the first surface and transparent; and a diffraction grating provided on the second surface side relative to the glass plate and having a plurality of grooves formed by a resist so as to propagate the light corresponding to the image while diffracting it; The thickness of the resist film between the bottom surface of the groove and the glass plate is determined based on the wavelength of the light diffracted in the groove.

2. The projection substrate according to claim 1, wherein: The thickness of the resist film between the bottom surface of the groove and the glass plate is determined based on the depth of the groove and the pitch of the groove.

3. The projection substrate according to claim 1 or 2, wherein: The thickness of the resist film is not less than 10 nanometers and less than 500 nanometers.

4. The projection substrate according to claim 1 or 2, wherein: The difference between the refractive index of the resist and the refractive index of the glass plate is 0.4 or less.

5. The projection substrate according to claim 1 or 2, wherein: The diffraction grating has a filling factor of 0.05 or more and 0.95 or less.

6. The projection substrate according to claim 1 or 2, comprising: a first diffraction grating for reflecting the light incident from the first surface in a predetermined direction; a second diffraction grating that diffracts a portion of the light incident from the first diffraction grating; as well as a third diffraction grating that reflects at least a portion of the light incident from the second diffraction grating and projects the reflected light as image light, The thickness of the resist film between the bottom surface of the grooves of the second diffraction grating and the glass plate is determined based on the wavelength of light diffracted in the grooves.

7. The projection substrate according to claim 1 or 2, comprising a plurality of glass plates, The diffraction grating for diffracting the light in different wavelength ranges is formed on each of the plurality of glass plates. The thickness of each of the resist films corresponding to the plurality of glass plates is determined based on the wavelength of the light diffracted by the diffraction grating formed on each of the glass plates.

8. The projection substrate according to claim 7, wherein: The diffraction grating corresponding to a first wavelength range has a larger thickness of the resist film than the diffraction grating corresponding to a second wavelength range shorter than the first wavelength range.

9. A method for manufacturing a projection substrate, which is a method for manufacturing a projection substrate for projecting an image, and the method for manufacturing a projection substrate comprises the following steps: Coating the resist on a transparent glass plate; pressing a mold having a plurality of grooves formed therein onto the resist to a position determined based on the wavelength of light diffracted in the plurality of grooves; In a state where the mold is pressed onto the resist, hardening the resist by ultraviolet rays or heat; as well as The mold is removed from the resist.

Images