Diffusion plate, lighting device, and image display device

Abstract

To provide a novel, improved optical body capable of providing more uniform light distribution, an illumination device, and an image display device.SOLUTION: According to an aspect of the present invention, an optical body is provided to clear the above challenge, the optical body having a composite structure comprising principal structures continuously spreading in a base material plane. A phase distribution of each principal structure in the base material plane corresponds to an amplitude distribution obtained by Fourier transforming a pupil function of a two-dimensional optical aperture, and a peak ratio is 2.5 or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to Diffuser The present invention relates to a lighting device and an image display device. [Background technology]

[0002] In order to change the diffusion characteristics of light, a diffuser plate that diffuses the incident light in a desired direction is often used. Such a diffuser plate has an optical body on its surface to realize a desired diffusion state, and one type of such optical body has a microlens structure in which multiple microlenses with a size of about several tens of μm are arranged.

[0003] For example, Patent Document 1 below discloses an optical film having a microlens array in which a plurality of microlenses are irregularly arranged, and the vertex positions and vertex intervals of the microlenses formed in the microarray satisfy certain conditions. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2003-4907 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, there is a strong demand for a diffuser plate to have a uniform light distribution property, that is, to distribute light as uniformly as possible. However, the reality is that no diffuser plate with a sufficiently uniform light distribution property has yet been proposed.

[0006] Therefore, the present invention has been made in consideration of the above problems, and an object of the present invention is to provide a new and improved light distribution device capable of improving uniform light distribution. Diffuser The present invention aims to provide a lighting device and an image display device. [Means for solving the problem]

[0007] In order to solve the above problems, according to one aspect of the present invention, A diffusion plate in which a composite structure having a shape formed by combining a plurality of main structures is continuously developed within the surface of a base material, a phase distribution in a plane of the base material of the primary structure corresponds to an amplitude distribution obtained by Fourier transforming a pupil function of a two-dimensional optical aperture, the pupil function is a pupil function whose light intensity distribution indicates a Gaussian distribution, a central point of each of the plurality of primary structures is disposed at an arbitrary position on an x2y2 plane of the base material based on a preset in-plane existence probability P of the primary structures; each of the plurality of primary structures has a plurality of convex portions and a plurality of concave portions arranged concentrically, and a cross-sectional shape of the primary structures is such that the height of the primary structures changes periodically such that the height of the convex portions and the depth of the concave portions decrease as the distance from a center point increases; a shape of each of the plurality of primary structures is randomly determined for each of the primary structures based on a preset amplitude A, a period Λ, an existence region T, and a periodic perturbation δ of the primary structures; the shape of the composite structure is a shape formed on the x2y2 plane by combining the multiple primary structures by simply adding up heights z2 of the multiple primary structures arranged on the x2y2 plane of the base material, The diffusion plate is characterized in that the in-plane existence probability P, the existence region T, the period Λ, and the periodic perturbation δ satisfy at least one of the following conditions 1 to 3. Condition 1 Λ≧5μm Condition 2 P≧0.3% and Λ≧3μm Condition 3 P≧0.2%, Λ≧3μm, T≧10Λ, and δ≧30% (Condition 3-1) Or P ≧ 0.2%, Λ ≧ 4 μm, T > 10Λ, and δ ≧ 0% (condition 3-2) is satisfied.

[0008] Here, the two-dimensional optical aperture may have a circular, rectangular, polygonal or free-form shape.

[0010] Also, The aboveThe phase distribution of the composite structure is Multiple Main structure The above It may be a simple sum of phase distributions.

[0014] According to another aspect of the present invention, there is provided an illumination device comprising the above optical body disposed on a surface of a light source.

[0015] According to another aspect of the present invention, there is provided an image display device, characterized in that the above optical body is disposed between a light source and a display unit. Effect of the Invention

[0016] As described above, according to the present invention, it is possible to improve the uniform light distribution of the optical body. [Brief description of the drawings]

[0017] [Figure 1] FIG. 2 is a perspective view showing a structure of an optical body according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a plan view showing the structure of a primary structure according to the embodiment. [Diagram 3] FIG. 2 is a cross-sectional view showing the structure of a main structure. [Figure 4] 1 is a graph showing an example of a pupil function. [Diagram 5] FIG. 4 is an explanatory diagram showing a procedure for creating a pattern image. [Figure 6] FIG. 4 is an explanatory diagram showing a procedure for creating a pattern image. [Figure 7] 1 is a flowchart showing a procedure for producing an optical body. [Figure 8] 11 is a bitmap image showing an example of a pattern image according to an embodiment. [Figure 9] 1 is a graph showing an example of light distribution characteristics of an optical body according to an example. [Figure 10] 1 is a confocal microscope image showing the structure of the composite structure. [Figure 11] FIG. 2 is a cross-sectional view showing the structure of a composite structure. [Figure 12]11 is a simulation image showing the light distribution characteristic of the optical body according to the example. [Figure 13] 11 is a simulation image showing the light distribution characteristic of the optical body according to the example. [Figure 14] 11 is a bitmap image showing an example of a pattern image according to an embodiment. [Figure 15] 1 is a graph showing an example of light distribution characteristics of an optical body according to an example. [Figure 16] 1 is a confocal microscope image showing the structure of the composite structure. [Figure 17] 11 is a simulation image showing the light distribution characteristic of the optical body according to the example. [Figure 18] 11 is a simulation image showing the light distribution characteristic of the optical body according to the example. [Figure 19] 11 is a bitmap image showing an example of a pattern image according to an embodiment. [Figure 20] 11 is a simulation image showing the light distribution characteristic of the optical body according to the example. [Figure 21] 11 is a simulation image showing the light distribution characteristic of the optical body according to the example. [Figure 22] 1 is a graph showing an example of light distribution characteristics of an optical body according to an example. [Diagram 23] 1 is a confocal microscope image showing the structure of the composite structure. [Figure 24] 4 is a laser projection image showing the light distribution characteristic of the optical body according to the example. [Diagram 25] 11 is a simulation image showing the light distribution characteristic of the optical body according to the example. [Figure 26] 1 is a graph showing an example of light distribution characteristics of an optical body according to an example. [Figure 27] 1 is a confocal microscope image showing the structure of the composite structure. [Figure 28] 4 is a laser projection image showing the light distribution characteristic of the optical body according to the example. [Figure 29] 11 is a simulation image showing the light distribution characteristic of the optical body according to the example. [Diagram 30] 1 is a bitmap image of a microlens array. [Diagram 31] 13 is a simulation image showing the light distribution characteristic of an optical body according to a comparative example. [Diagram 32] 11 is a luminance profile showing an example of a peak ratio value. [Diagram 33] 11 is a luminance profile showing an example of a peak ratio value. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same functional configurations are designated by the same reference numerals, and duplicated explanations will be omitted.

[0019] <1. Overall configuration of the optical body> First, the overall configuration of an optical body 1 according to this embodiment will be described with reference to Figures 1 and 2. The optical body 1 is used, for example, as a light diffusion plate, and includes a substrate 10 and a synthetic structure layer 15 formed on the surface of the substrate 10.

[0020] The substrate 10 is a substrate made of a material that can be considered transparent in the wavelength band of light incident on the optical body 1 according to this embodiment. The substrate 10 may be in the form of a film or a plate. The material of the substrate is not particularly limited, and for example, known resins such as polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polycarbonate (PC), cycloolefin copolymer (COC), cycloolefin polymer (COP), triacetylcellulose (TAC), etc. can be used as the substrate 10, or known optical glass such as quartz glass, borosilicate glass, white plate glass, etc. can be used. In Figure 1, the base material 10 is illustrated as being rectangular, but the shape of the base material 10 is not limited to a rectangle, and may have any shape (e.g., circular, etc.) depending on the shape of an illumination device, image display device, etc. in which the optical body 1 is to be mounted.

[0021] The synthetic structure layer 15 has a synthetic structure 20 formed therein. The synthetic structure 20 has a shape in which a large number of primary structures 30 are combined, and is continuously formed within the surface of the substrate 10. Detailed configurations of the synthetic structure 20 and the primary structures 30 will be described later. The synthetic structure layer 15 is composed of, for example, a cured product of a curable resin. The curable resin is composed of a resin that can be considered transparent in the wavelength band of light incident on the optical body 1 according to this embodiment. Examples of such resins include ultraviolet-curable acrylic resin and ultraviolet-curable epoxy resin.

[0022] <2. Detailed configuration of composite structure 20 and primary structure 30> Next, detailed configurations of the composite structure 20 and the primary structure 30 will be described with reference to Fig. 2 to Fig. 6. As described above, the composite structure 20 has a shape in which a large number of primary structures 30 are combined.

[0023] 2 and 3 show a structural example of the primary structure 30. In FIG. 2, the primary structure 30 is drawn on an x2y2 plane 100. The x2y2 plane 100 is a plane on which a pattern image corresponding to a design drawing of the composite structure 20 is drawn. The pattern image is created, for example, by using a computer. The composite structure 20 drawn in the pattern image is formed in the surface of the base material 10. Therefore, the x2y2 plane 100 is a plane for defining the surface shape of the base material 10. A method for generating the pattern image will be described later. FIG. 3 is an AA cross-sectional view of FIG. 2.

[0024] The phase distribution of the primary structure 30 in the plane of the base material 10 (in other words, in the x2y2 plane 100) corresponds to an amplitude distribution obtained by Fourier transforming the pupil function of the two-dimensional optical aperture. This amplitude distribution indicates the amplitude distribution (so-called point spread function) on the image plane of the two-dimensional optical aperture. Here, the pupil function is not particularly limited as long as it roughly corresponds to the set light intensity distribution (light intensity distribution of the assumed light source), but it is preferable that the pupil function is a pupil function that shows a Gaussian distribution of light intensity, and more preferable that the pupil function is a uniform light intensity distribution (hereinafter also referred to as a "homogeneous pupil function"). In this case, the homogeneous light distribution of the optical body 1 can be further improved. In the following embodiment, the pupil function is described on the premise that the pupil function is a homogeneous pupil function.

[0025] Graph L1 in Fig. 4 shows an example of a homogeneous pupil function. The x1y1 plane in Fig. 4 is a plane on which the optical aperture is drawn, and the z1 axis indicates light intensity. In this example, the optical aperture is circular, and the light intensity within the optical aperture is uniform (i.e., light intensity = constant value a), and the light intensity in other regions is zero. Note that the optical aperture is not necessarily limited to a circular shape, and may be rectangular, polygonal, or free-form.

[0026] The amplitude distribution obtained by Fourier transforming such a homogeneous pupil function over the entire aperture surface is represented by, for example, a Sinc function. For this reason, in this embodiment, the phase distribution (i.e., vibration waveform) of the primary structure 30 is represented by a Sinc function as shown in Figs. 2 and 3. More specifically, the center point 31 of the primary structure 30 is the point of zero phase, and the height z2 of the primary structure 30 at a distance r from the center point 31 is represented by the following formulas (1) and (2). In formulas (1) and (2), A represents the amplitude (μm) of the primary structure 30, and Λ represents the period (μm) of the primary structure 30.

[0027]

number

[0028] As shown in Figures 2 and 3, the primary structure 30 has a large number of protrusions 32 and recesses 33, and the amount of variation in height z2 (i.e., the height of the protrusions 32 and the depth of the recesses 33) decreases as the distance r from the center point 31 increases.

[0029] The reason why the primary structure 30 has such a phase distribution is as follows. That is, when the amplitude distribution obtained by Fourier transforming the homogeneous pupil function is further Fourier transformed (so-called inverse Fourier transform), the original homogeneous pupil function is obtained. For example, when the amplitude distribution is represented by a Sinc function, its Fourier transform image becomes the homogeneous pupil function.

[0030] On the other hand, if the surface structure of the optical body 1 is considered as a pupil function, the amplitude distribution of the light transmitted through (or reflected from) the optical body 1 is considered to be equivalent to the Fourier transform of the vibration waveform of the surface structure of the optical body 1. Therefore, if the surface structure of the optical body 1 is a composite structure 20 obtained by combining the above-mentioned primary structures 30, it is considered that the (light beam of) light transmitted through the optical body 1 has an amplitude distribution equivalent to the above-mentioned homogeneous pupil function. For this reason, the primary structure 30 has a phase distribution equivalent to the amplitude distribution obtained by Fourier transforming the homogeneous pupil function. As a result, in this embodiment, it is possible to improve the homogeneous light distribution of the light transmitted through (or reflected from) the optical body 1.

[0031] As shown in Fig. 3, the height z2 of the primary structure 30 is maximum at the convex portion 32 at the center point 31 and is minimum at the concave portion 33 closest to the center point 31. It is preferable that the optical path difference between the light passing through the center point 31 and the light passing through the concave portion 33 closest to the center point 31 is one wavelength of light. Specifically, when the wavelength of the light incident on the optical body 1 is λ s ~λ e When the amplitude A varies within a range of m (μm), it is preferable that the amplitude A of the m-th primary structure 30 arranged on the x2y2 plane 100 satisfies the following formula (3). Note that the m-th primary structure 30 refers to the primary structure 30 whose central point 31 is determined as the mth in the process of determining the position of the central point 31, which will be described later.

[0032]

number

[0033] In formula (3), n is the relative refractive index of the composite structure layer 15, and R m is a random number (real number) between 0 and 1. When the amplitude A is expressed by formula (3), the wavelength λ s ~λ e It is possible to diffuse light with high uniformity for any incident light with a diameter of 1 / 4 (μm).

[0034] The composite structure 20 has a shape in which a large number of primary structures 30 are combined. First, a method for combining the primary structures 30 (a method for fabricating the composite structure 20) will be described with reference to FIGS. 5 to 6. The composite structure 20 is fabricated by a computer. First, as shown in FIG. 5, an x2y2 plane 100 is set in a virtual space. The x2y2 plane 100 is a collection of a plurality of pixels. The shape and size of the x2y2 plane 100, and the size in real space corresponding to one pixel (so-called resolution) may be set according to the shape and size of the optical body 1 to be actually fabricated. The resolution depends on the function of the exposure device, but is preferably set to about 0.2 to 0.8 μm / px in order to improve the accuracy of the composite structure 20. The size of the x2y2 plane 100 is specified by the number of pixels constituting the x2y2 plane 100. For example, when the x2y2 plane 100 is a rectangle, the size of the x2y2 plane 100 is defined by the number of pixels on the long side multiplied by the number of pixels on the short side. The size of the x2y2 plane 100 multiplied by the resolution is the size of the optical body 1 in real space, specifically, the size of the surface of the base material 10.

[0035] Next, the x2y2 plane 100 is scanned pixel by pixel in the x2 direction (direction of arrow P). Then, for each pixel, it is determined whether or not to place the center point 31 of the primary structure 30 based on the in-plane presence probability P (%). The in-plane presence probability P is set by an operator (an operator who fabricates the optical body 1). After scanning for the same y2 coordinate is completed, the scanning position is shifted by one pixel in the y2 direction, and the same process is repeated until scanning of the entire x2y2 plane 100 is completed. As a result, the center point 31 is placed at an arbitrary position on the x2y2 plane 100.

[0036] Next, as shown in Fig. 6, the primary structures 30 are placed at each center point 31 according to the amplitude A, period Λ, existence region T, and periodic perturbation δ of the primary structures 30 that have been set in advance by the worker. Here, the existence region T corresponds to the radius of the primary structures 30 in the x2y2 plane 100, and is an integer multiple of the period Λ (=αΛ, where α is an integer and indicates the number of repetitions of the period Λ). The periodic perturbation δ (%) is the variation in the period Λ, and a specific value of the period Λ is randomly determined within the range of the periodic perturbation for each primary structure 30. When the periodic perturbation is β%, the period Λ of each primary structure 30 is the period Λ±(period Λ×β%).

[0037] Next, the primary structures 30 are synthesized. Specifically, the heights z2 of the primary structures 30 are simply summed for each pixel on the x2y2 plane 100. As a result, the synthesized structure 20 is formed on the x2y2 plane 100. In other words, the height z2 of the synthesized structure 20 at each pixel on the x2y2 plane 100 is a simple sum of the heights z2 of the primary structures 30 randomly arranged on the x2y2 plane 100. Note that the synthesis method is not limited to the simple sum, and other synthesis methods may be used.

[0038] This produces a pattern image. The height z2 of the composite structure 20 in the pattern image is expressed, for example, by the gradation of the color of the pixel. Therefore, the pattern image is a so-called bitmap image. The height z2 of each part of the composite structure 20 in real space is defined as follows. That is, the z2 axis is defined in the height (thickness) direction of the base material 10, and the direction away from the base material 10 is defined as the positive direction. The origin of z2=0 (the point where the phase of the Sinc function is zero) is defined on the z2 axis. The height z2 of each part of the composite structure 20 is defined as the coordinate value of the z2 axis defined in this way. It is preferable that the difference δZ between the maximum value and the minimum value of the height z2 in the entire region of the composite structure 20 is 4.5 or more. In this case, it is expected that the uniform light distribution of the light will be improved.

[0039] Then, a master (having an inverted shape of the composite structure 20 formed on its surface) is produced based on this pattern image, and the optical body 1 is produced using this master as a transfer mold. The composite structure 20 designed by the pattern image is formed in the optical body 1. Light transmitted through or reflected by such an optical body 1 has a high uniform light distribution. Specifically, the peak ratio value is 2.5 or less. The peak ratio value is defined as the ratio between the peak level and the base level of the luminance profile of the light. The luminance profile indicates the luminance at each position on the screen onto which the diffused light is irradiated.

[0040] Here, examples of peak ratio values ​​will be described with reference to Figs. 32 and 33. Graph L10 shown in Fig. 32 is an example of a luminance profile in which the peak ratio value is 2.5 or less (i.e., one type of example of this embodiment), and graph L20 shown in Fig. 33 is an example in which the peak ratio value is greater than 2.5 (i.e., one type of comparative example of this embodiment). The horizontal axis of Figs. 32 and 33 indicates the position on the screen, and the vertical axis indicates the luminance. The peak level LP is defined as the maximum value of the luminance profile. On the other hand, the base level BL is defined as the average (arithmetic mean) luminance level of the area with a high amplitude frequency. In a luminance profile in which the peak ratio value is 2.5 or less, the luminance is homogeneous on the screen. In contrast, in a luminance profile in which the peak ratio value is greater than 2.5, the peak P0 of the 0th order light or the peak P1 of the 1st order light is extremely large, and the homogeneous light distribution of the light is impaired.

[0041] In order for the peak ratio value of the optical body 1 to be 2.5 or less, the in-plane existence probability P, existence region T, period Λ, and periodic perturbation δ of the primary structures 30 must satisfy at least one of the following conditions 1 to 3. Condition 1 Λ≧5μm Condition 2 P≧0.3% and Λ≧3μm Condition 3 P≧0.2%, Λ≧3μm, T≧10Λ, and δ≧30% (Condition 3-1) Or P ≧ 0.2%, Λ ≧ 4 μm, T > 10Λ, and δ ≧ 0% (condition 3-2) Meet the following.

[0042] Here, when the diffused light from the diffusion plate is irradiated onto a screen, a macroscopic mottled pattern (so-called macroscopic mottled pattern) may be observed within the irradiated area of ​​the screen. Such mottled pattern is also one of the causes of impairing the uniform light distribution. As verified in the examples described later, the optical body 1 according to this embodiment can also suppress the occurrence of such mottled patterns.

[0043] As described above, according to this embodiment, the composite structure 20 of the optical body 1 has a shape obtained by combining the primary structures 30. The phase distribution of the primary structure 30 corresponds to an amplitude distribution obtained by Fourier transforming the pupil function (i.e., homogeneous pupil function) of a two-dimensional optical aperture having a uniform light intensity distribution. This allows the optical body 1 to emit diffused light with high efficiency and high homogeneous light distribution (with less macroscopic spots) for various incident lights (for example, collimated light or other types of light). The pupil function is not necessarily limited to a homogeneous pupil function, and is not particularly limited as long as it roughly corresponds to the set light intensity distribution (light intensity distribution of the assumed light source). For example, the pupil function may be a pupil function whose light intensity distribution indicates a Gaussian distribution, and it is considered that the same effect as described above can be obtained in this case as well.

[0044] The diffused light emitted from such an optical body 1 has very little macroscopic spots, good visibility, and high homogeneity. Therefore, the optical body 1 efficiently contributes to the actions of reflection, transmission, interference, absorption, waveguiding, and the like of incident light. That is, in this embodiment, the light distribution component of the reflected light with respect to the incident light entering the composite structure 20 of the optical body 1 is controlled, or the light distribution component of the transmitted light beam is controlled, thereby realizing diffusion with a homogeneous energy distribution and little macroscopic spots.

[0045] The sheet film body or various devices to which the optical body 1 is applied have excellent functions of uniformly diffusing light and enlarging the optical aperture due to the high homogeneity of the diffused light. Therefore, by applying the optical body 1 of this embodiment to backlights, general or special lighting devices, or image display devices that display high-quality images with high brightness and high gradation (e.g., 8 bit, 16 bit, 24 bit, etc.), the accuracy and reliability of these devices can be dramatically improved. The optical body 1 can also be applied to various devices including the above, such as lighting devices, image display devices, optical measurement devices, measurement medical devices, and ultraviolet light application devices.

[0046] <3. Manufacturing method of optical body> Next, a method for manufacturing the optical body 1 will be described with reference to the flowchart shown in FIG. 7. In step S100, a pattern image is created. To create a pattern image, first, a computer capable of creating a pattern image is prepared. The computer includes, as hardware components, a CPU (Central Processing Unit, i.e., a processor), a RAM (Random Access Memory), a ROM (Read Only Memory), a hard disk, various input operation devices (keyboard, mouse, etc.), a display, a communication device, etc. The ROM stores information necessary for processing by the computer, particularly programs necessary for creating the pattern image, etc. The CPU reads out and executes the programs stored in the ROM.

[0047] The operator first inputs the shape, size, and resolution of the pattern image, the in-plane existence probability P of the primary structure 30, the amplitude A, the period Λ, the existence region T, and the periodic perturbation δ into the electronic computer. For the existence region T, the number of repetitions α may be input. Also, the concaves and convexes of the primary structure 30 may be reversed. In this case, the operator inputs information to the effect that the concaves and convexes of the primary structure 30 are to be reversed into the electronic computer.

[0048] Next, the electronic computer creates a pattern image based on the information given by the operator. First, the electronic computer sets an x2y2 plane 100 in a virtual space as shown in FIG. 5. The shape and size of the x2y2 plane 100 are set based on the shape and size of the input pattern image. Next, the electronic computer scans the x2y2 plane 100 pixel by pixel in the x2 direction (arrow P direction). Then, for each pixel, it is determined whether or not to place the center point 31 of the primary structure 30 based on the in-plane existence probability P (%). After the scan for the same y2 coordinate is completed, the scan position is shifted by one pixel in the y2 direction, and the same process is repeated until the scan of the entire area of ​​the x2y2 plane 100 is completed. As a result, the center point 31 is placed at an arbitrary position on the x2y2 plane 100.

[0049] Next, as shown in FIG. 6, the electronic computer places the primary structure 30 at each center point 31 in accordance with the amplitude A, period Λ, existence region T, and periodic perturbation δ of the primary structure 30 that have been set in advance by the operator.

[0050] Next, the electronic computer synthesizes the primary structures 30. Specifically, the heights z2 of the primary structures 30 are simply summed for each pixel on the x2y2 plane 100. As a result, the composite structure 20 is formed on the x2y2 plane 100. That is, a pattern image is created. Note that the synthesis method is not limited to the simple sum, and other synthesis methods may be used. Note that the process of step S100 may be performed at any timing before the process of step S105 is performed.

[0051] Next, in step S101, an operator cleans a substrate. The substrate may be, for example, a roll-shaped substrate such as a glass roll, or a flat substrate such as a glass wafer. The substrate may also be a silicon wafer.

[0052] In step S103, the worker forms a resist on the surface of the substrate after cleaning. Here, examples of the resist include resists using metal oxides and resists using organic substances. The resist may be a positive or negative photoreactive resist. Specific examples include PMER-LA900 manufactured by Tokyo Ohka Kogyo Co., Ltd. and AZ4620 manufactured by AZ Electronic Materials Co., Ltd. A coupling agent may be added to the resist. The resist may have a thickness of, for example, about 2 to 15 μm. The resist formation process is realized by coating or dipping for roll-shaped substrates, and by various coating processes for flat substrates.

[0053] Next, in step S105, an exposure process is performed on the substrate on which the resist has been formed. This exposure process can be performed by appropriately applying various known exposure methods, such as exposure using a grayscale mask or the like (including multiple exposure by overlapping multiple grayscale masks), grayscale exposure on a flat plate or roll plate, and laser exposure using a picosecond pulse laser, femtosecond pulse laser, or the like. An operator inputs the above-mentioned pattern image into an apparatus that performs the exposure process. The apparatus performs exposure based on the pattern image. The wavelength of the laser may be appropriately selected, and examples include 405 nm, 436 nm, and the like. These apparatuses expose the resist based on the pattern image. Exposure is performed for each pixel according to the resolution.

[0054] In step S107, the operator performs alkaline development on the exposed substrate. Examples of the developer include NMD-3, NMD-7, PMER P-7G (all manufactured by Tokyo Ohka Kogyo Co., Ltd., with equivalent components), TMAH (tetramethylammonium hydroxide), etc.

[0055] In step S111, the worker prepares a master. For example, the worker may prepare a master (glass master, etc.) by etching (for example, glass etching using CF4 gas, Ar gas, etc.) the base after alkali development. The worker may also perform Ni sputtering (for example, equivalent to 20 to 60 nm) or electroforming pretreatment on the base after alkali development, and then perform Ni electroforming to peel off the coating from the base. This coating may then be used as the master (metal master). The electroforming pretreatment is performed by immersing the developed base in a Ni bath such as a Ni sulfamate bath. The thickness of the coating may be selected appropriately. On the surface of the master, irregularities having the same shape as the synthetic structure 20 are formed.

[0056] In step S113, the worker uses the completed master disk to create a mold such as a soft mold. For example, an uncured curable resin is applied onto a substrate, and the unevenness of the master disk is pressed against the uncured curable resin layer. The curable resin is cured in this state. The soft mold is produced by the above steps. The materials of the substrate and the curable resin may be the same as those of the optical body 1. The unevenness that is the inverted shape of the composite structure 20 is formed on the surface of the soft mold.

[0057] In step S115, the worker performs a transfer process on the substrate 10. For example, the worker applies an uncured curable resin onto the substrate 10, and presses the unevenness of the mold onto the uncured curable resin layer. The curable resin is cured in this state. This produces the optical body 1. In step S117, the worker forms a protective film or the like on the surface of the optical body 1 as necessary. The optical body 1 is produced by the above steps. Note that the soft mold production step may be omitted, and the optical body 1 may be produced directly from the master master. In this case, unevenness that is the inverted shape of the composite structure 20 is formed on the surface of the master master.

[0058] It should be noted that the flow of the manufacturing method shown in FIG. 7 is merely an example, and the manufacturing method of the optical body 1 according to this embodiment is not limited to the example shown in FIG.

[0059] <4. Application examples of optical bodies> The application examples of the optical body are not particularly limited, and may be applied to any field in which uniform light distribution of diffused light is required. The optical body 1 may be applied to, for example, a lighting device, an image display device, an optical measurement device, a measurement medical device, and an ultraviolet light application device. When the optical body 1 is applied to a lighting device, the optical body 1 may be disposed on the surface of a light source. When the optical body 1 is applied to an image display device, the optical body 1 may be disposed between a light source and a display unit. In either case, the type of the light source is not particularly limited. The light source may be one that emits collimated light or telecentric light including parallel principal rays, or may be another type of light source. EXAMPLES

[0060] <1. Examples A to E> In Examples A to E, the optical body 1 was actually produced and its light distribution characteristics were evaluated. Additionally, the light distribution characteristics of Examples A to E were also evaluated by simulation.

[0061] (1-1. Example A) In Example A, the optical body 1 was produced according to the above-mentioned manufacturing method. Schematically, the substrate after alkali development was subjected to electroforming pretreatment, and then Ni electroforming was performed to peel off the coating from the substrate. This coating was then used as a master master (metal master). The shape of the pattern image was rectangular, the size was 200×200px (rectangle), the resolution was 0.8 μm / px, the in-plane existence probability P was 0.1%, the amplitude A was a value satisfying the above-mentioned mathematical formula (3) (the wavelength of light was 532 nm), the period Λ was 5 μm, the existence region T was 50Λ, and the periodic perturbation δ was 10%. In addition, the refractive index of the substrate 10 and the composite structure layer 15 was 1.5, and the thickness of the substrate 10 was 100 μm.

[0062] FIG. 8 shows a pattern image. In this pattern image, the height z2 of the composite structure 20 is drawn in eight gradations. As is clear from FIG. 8, it can be seen that the concaves and convexes of the composite structure 20 are randomly distributed in the pattern image. For comparison, the inventors created a pattern image of a microlens array shown in FIG. 30. In this example, the diameter of the microlens in plan view is set to 15 μm, and the diameter is varied by 5% perturbation for each microlens. Furthermore, the radius of curvature of each microlens is set to 8 μm, and the radius of curvature is varied by 5% perturbation for each microlens. Note that the pattern image in FIG. 30 is obtained by tiling the same pattern image in a 2×2 array. As is clear from this example, regions A in which the shapes of the concaves and convexes are similar are scattered. Such regions A can be a cause of macroscopic spots. In Example A, which does not have such regions A, the occurrence of macroscopic spots is suppressed.

[0063] Next, the light distribution characteristics of this optical body 1 were evaluated. A Mini-Diff manufactured by Cybernet Systems was used as the measuring device. Collimated light with a wavelength of 650 nm was incident on optical body 1 from the substrate side, and the luminance distribution of the diffused light was measured within a 20 mm opening. The average value was measured for each angle of incidence of the diffused light into the opening, and this was taken as the luminance value. The results are shown in Figure 9. The horizontal axis indicates the angle of incidence of the diffused light, and the vertical axis indicates the luminance. As is clear from this example, a distribution with high uniform light distribution can be obtained.

[0064] Fig. 10 shows a confocal microscope image of the composite structure 20 of the optical body 1. Fig. 11 shows the cross-sectional shape of the composite structure 20 along the line L2, specifically, the cross-sectional profile of a confocal microscope image of the surface structure of Fig. 10. The vertical axis indicates the height from the surface of the base material 10, and the horizontal axis indicates the position on the line L2. As is clear from Figs. 10 and 11, it can be seen that the composite structure 20 is formed on the surface of the optical body 1. In addition, since the composite structure 20 is formed by combining primary structures 30 arranged randomly within the plane of the base material 10, the height z2 varies randomly.

[0065] The inventor evaluated the light distribution characteristics of the optical body 1 by simulation. Virtual-Lab by Siemens was used as the simulation software. The simulation conditions were as follows. That is, a collimated light source with a diameter of 0.8 mm was used as the light source, and the wavelength was 532 nm (and additional wavelengths of 473 nm and 635 nm). The shape of the optical body 1 was a circle with a diameter of 0.8 mm, and the thickness of the substrate 10 was 100 μm. Furthermore, the refractive index of the substrate and the composite structure layer 15 was 1.5. Then, collimated light was incident from the substrate side, and diffused light was irradiated onto a virtual screen surface 100 mm away from the optical body 1. The results are shown in Figs. 12 and 13. Fig. 12 shows a projected image projected on a screen when light with a wavelength of 532 nm was incident on the optical body 1, and Fig. 13 shows a projected image projected on a screen when composite light with wavelengths of 473 nm, 532 nm, and 635 nm was incident on the optical body 1. The peak ratio value is calculated based on the luminance distribution of this projected image. It can be seen that in all the examples, the diffused light has high uniformity.

[0066] (1-2. Example B) In Example B, the optical body 1 was produced under the same conditions as in Example A except that the periodic perturbation was set to 10%, and the light distribution characteristics were evaluated in the same manner as in Example A. FIG. 14 shows a pattern image. In this pattern image, the height z2 of the composite structure 20 is depicted in eight gradations. As is clear from FIG. 14, it can be seen that the concaves and convexes of the composite structure 20 are randomly distributed within the pattern image.

[0067] Fig. 15 shows the light distribution characteristics measured using Mini-Diff. A highly uniform light distribution is also obtained in Example B. Fig. 16 shows a confocal microscope image of the composite structure 20 of the optical body 1. As is clear from Fig. 16, it can be seen that the composite structure 20 is formed on the surface of the optical body 1.

[0068] Figures 17 and 18 show the results of the simulation. Figure 15 shows an image projected on a screen when light with a wavelength of 532 nm is incident on the optical body 1, and Figure 16 shows an image projected on a screen when composite light with wavelengths of 473 nm, 532 nm, and 635 nm is incident on the optical body 1. It can be seen that in both examples, the diffused light has high homogeneity.

[0069] (1-3. Example C) In Example C, the optical body 1 was produced under the same conditions as in Example A except that the periodic perturbation was set to 0%, and the light distribution characteristics were evaluated in the same manner as in Example A. Fig. 19 shows a pattern image. In this pattern image, the height z2 of the composite structure 20 is depicted in eight gradations. As is clear from Fig. 19, it can be seen that the concaves and convexes of the composite structure 20 are randomly distributed within the pattern image.

[0070] Figures 20 and 21 show the results of the simulation. Figure 20 shows an image projected onto a screen when light with a wavelength of 532 nm is incident on the optical body 1, and Figure 21 shows an image projected onto a screen when composite light with wavelengths of 473 nm, 532 nm, and 635 nm is incident on the optical body 1. It can be seen that in both examples, the diffused light has high homogeneity.

[0071] (1-4. Example D) In Example D, the optical body 1 was produced under the same conditions as Example A, except that the in-plane existence probability P was 0.6% and the period Λ was 4 μm, and the light distribution characteristics were evaluated in the same manner as Example A. FIG. 22 shows the light distribution characteristics measured using Mini-Diff. A distribution with high uniform light distribution is also obtained in Example D. FIG. 23 shows a confocal microscope image of the composite structure 20 of the optical body 1. As is clear from FIG. 23, it can be seen that the composite structure 20 is formed on the surface of the optical body 1. FIG. 24 shows a projected image obtained when the diffused light obtained under the same conditions as FIG. 22 is irradiated onto a screen. The distance from the optical body 1 to the screen was set to 100 mm. FIG. 25 shows the results of a simulation. FIG. 25 shows a projected image projected onto a screen when light with a wavelength of 532 nm is incident on the optical body 1. As is clear from FIG. 24 and FIG. 25, it can be seen that the diffused light has high uniformity.

[0072] (1-5. Example E) In Example E, the optical body 1 was produced under the same conditions as in Example A except that the in-plane existence probability P was set to 0.5%, and the light distribution characteristics were evaluated in the same manner as in Example A. FIG. 26 shows the light distribution characteristics measured using Mini-Diff. A distribution with high uniform light distribution is also obtained in Example E. FIG. 27 shows a confocal microscope image of the composite structure 20 of the optical body 1. As is clear from FIG. 27, it can be seen that the composite structure 20 is formed on the surface of the optical body 1. FIG. 28 shows a projected image obtained when the diffused light obtained under the same conditions as in FIG. 26 is irradiated onto a screen. The distance from the optical body 1 to the screen was set to 100 mm. FIG. 29 shows the results of a simulation. FIG. 29 shows a projected image projected onto a screen when light with a wavelength of 532 nm is incident on the optical body 1. As is clear from FIG. 28 and FIG. 29, it can be seen that the diffused light has high uniformity.

[0073] <2. Examples 1 to 34 and Comparative Examples 1 to 9> In Examples 1 to 34 and Comparative Examples 1 to 9, in order to investigate the influence of the in-plane existence probability P, the period Λ, the existence region T, and the period perturbation δ on the light distribution characteristics, the light distribution characteristics of the optical body 1 in which these parameters were varied were evaluated by simulation. The specific method of the simulation was the same as in Example A. The parameters and results of each Example and Comparative Example are shown in Tables 1 to 8. In the observations of Tables 1 to 8, "Good light distribution" indicates a state in which ring light, spotted patterns, etc. are not observed (high homogeneity of diffused light). In other words, it indicates that diffused light similar to that in FIG. 12, etc. was observed. "Very thin ring light" indicates that an extremely thin ring light was observed, but the peak ratio value was 2.5 or less. "Ring light" indicates that the ring light was clearly observed, and the peak ratio value was greater than 2.5. An example of ring light is shown in FIG. 31. The "judgment" is "Good" if the peak ratio value is 2.5 or less, and "NG" if the peak ratio value is greater than 2.5.

[0074] [Table 1]

[0075] The periodic dependency of light distribution characteristics was evaluated in Examples 1 to 6 and Comparative Examples 1 and 2. As is clear from Examples 1 to 6 and Comparative Examples 1 and 2, it can be seen that good light distribution characteristics can be obtained if Λ≧5 μm (i.e., if Condition 1 is satisfied).

[0076] [Table 2] [Table 3]

[0077] In Examples 7 to 15 and Comparative Examples 3 to 5, the optical characteristics were evaluated by varying the in-plane existence probability while fixing the period Λ of the primary structures 30 at 3 or 4 μm. As is clear from Examples 7 to 15 and Comparative Examples 3 to 5, good light distribution characteristics can be obtained if P≧0.3% and Λ≧3 μm (i.e., if condition 2 is satisfied).

[0078] [Table 4] [Table 5] [Table 6] [Table 7] [Table 8]

[0079] In Examples 16 to 34 and Comparative Examples 6 to 16, the optical characteristics were evaluated by varying the presence region T and period perturbation δ while fixing the in-plane presence probability P of primary structures 30 and the period Λ to certain values. As is clear from Examples 16 to 34 and Comparative Examples 6 to 16, it can be seen that good light distribution characteristics can be obtained if P≧0.2%, Λ≧3 μm, T≧10Λ, and δ≧30% (Condition 3-1) or P≧0.2%, Λ≧4 μm, T>10Λ, and δ≧0% (Condition 3-2) (i.e., if Condition 3 is satisfied).

[0080] Although the preferred embodiment of the present invention has been described in detail above with reference to the accompanying drawings, the present invention is not limited to such an example. It is clear that a person having ordinary knowledge in the technical field to which the present invention pertains can conceive of various modified or altered examples within the scope of the technical ideas described in the claims, and it is understood that these also naturally belong to the technical scope of the present invention.

[0081] For example, in the above embodiment, the phase distribution of the primary structure 30 is represented by a Sinc function, but the present invention is not limited to this example. In other words, the phase distribution of the primary structure 30 may be any distribution that corresponds to an amplitude distribution obtained by performing a Fourier transform on a homogeneous pupil function. [Explanation of symbols]

[0082] 1 optical body 10 Base material 15 Composite structure layer 20 Composite structures 30 Main structure 31 center point 32 Convex 33 Recess

Claims

1. A diffusion plate in which a composite structure having a shape formed by combining a plurality of main structures is continuously developed within the surface of a base material, a phase distribution in a plane of the base material of the primary structure corresponds to an amplitude distribution obtained by Fourier transforming a pupil function of a two-dimensional optical aperture, the pupil function is a pupil function whose light intensity distribution indicates a Gaussian distribution, The center point of each of the plurality of primary structures is determined based on a preset in-plane existence probability P of the primary structures by calculating the x ２ y ２ It is placed at any position on the plane, each of the plurality of primary structures has a plurality of convex portions and a plurality of concave portions arranged concentrically, and a cross-sectional shape of the primary structures is such that the height of the primary structures changes periodically such that the height of the convex portions and the depth of the concave portions decrease as the distance from a center point increases; a shape of each of the plurality of primary structures is randomly determined for each of the primary structures based on a preset amplitude A, a period Λ, an existence region T, and a periodic perturbation δ of the primary structures; The shape of the composite structure is the x ２ y ２ The height z of the plurality of primary structures arranged on a plane ２ The x ２ y ２ A shape formed on a plane, The in-plane existence probability P, the existence region T, the period Λ, and the periodic perturbation δ satisfy at least one of the following conditions 1 to 3. Condition 1 Λ≧5μm Condition 2 P≧0.3% and Λ≧3 μm Condition 3: P≧0.2%, Λ≧3 μm, T≧10Λ, and δ≧30% (Condition 3-1) Or P≧0.2%, Λ≧4 μm, T>10Λ, and δ≧0% (Condition 3-2) is satisfied.

2. The diffuser of claim 1 , wherein the two-dimensional optical aperture has a circular, rectangular, polygonal, or free-form shape.

3. 3. The diffusion plate according to claim 1, wherein the phase distribution of the composite structure is a simple sum of the phase distributions of the plurality of primary structures.

4. 4. A lighting device comprising the diffusion plate according to claim 1 disposed on a surface of a light source.

5. 4. An image display device, comprising: a diffusion plate according to claim 1 disposed between a light source and a display unit.

Images