Optical body, illumination 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 an optical body, an illumination device, and an image display device. [Background technology]

[0002] To change the diffusion characteristics of light, diffusers that diffuse incident light in a desired direction are often used. Such diffusers have an optical element on their surface that realizes the desired diffusion state, and one type of such optical element has a microlens structure in which multiple microlenses, each about several tens of micrometers in size, are arranged.

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

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-4907 Summary of the Invention [Problem to be solved by the invention]

[0005] However, there is a strong demand for a diffuser plate that can distribute light as uniformly as possible, but the reality is that no diffuser plate with a sufficiently uniform light distribution 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 optical body, lighting device, and image display device that are capable of improving uniform light distribution. [Means for solving the problem]

[0007] In order to solve the above problem, according to one aspect of the present invention, there is provided an optical body in which a composite structure of a primary structure is continuously developed within the plane of a substrate, wherein the phase distribution of the primary structure within the plane of the substrate corresponds to an amplitude distribution obtained by Fourier transforming the pupil function of a two-dimensional optical aperture, and the peak ratio value is 2.5 or less.

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

[0009] The phase distribution may also be expressed by a Sinc function.

[0010] The phase distribution of the composite structure may be a simple sum of the phase distributions of the primary structures.

[0011] Furthermore, the period Λ of the phase distribution of the primary structure may satisfy the following condition 1. Condition 1 Λ≧5μm

[0012] Furthermore, the in-plane existence probability P and the period Λ of the primary structures may satisfy the following condition 2. Condition 2 P≧0.3% and Λ≧3μm

[0013] Furthermore, the in-plane existence probability P of the primary structure, the existence region T, the period Λ, and the periodic perturbation δ may satisfy the following condition 3. 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.

[0014] According to another aspect of the present invention, there is provided an illumination device, characterized in that the optical body described above is disposed on the 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. [Effects 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 explanation of the drawings]

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

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

[0019] <1. Overall structure 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 composite structure layer 15 formed on the surface of the substrate 10.

[0020] The substrate 10 is 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 examples of the substrate include known resins such as polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polycarbonate (PC), cycloolefin copolymer (COC), cycloolefin polymer (COP), and triacetylcellulose (TAC). Alternatively, known optical glasses such as quartz glass, borosilicate glass, and white plate glass may 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 rectangular, and may have any shape (e.g., circular) depending on the shape of an illumination device, image display device, etc. in which the optical body 1 is mounted.

[0021] The composite structure layer 15 has a composite structure 20 formed thereon. The composite structure 20 has a shape formed by combining a large number of primary structures 30, and is continuously formed within the surface of the substrate 10. The detailed configurations of the composite structure 20 and the primary structures 30 will be described later. The composite structure layer 15 is made of, for example, a cured product of a curable resin. The curable resin is made 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, the detailed configurations of the composite structure 20 and the primary structure 30 will be described with reference to Figures 2 to 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 an example of the structure 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 using, for example, a computer. The composite structure 20 drawn in the pattern image is formed within the surface of the substrate 10. Therefore, the x2y2 plane 100 is a plane for defining the surface shape of the substrate 10. A method for generating the pattern image will be described later. FIG. 3 is a cross-sectional view taken along the line AA of FIG. 2.

[0024] The phase distribution of the primary structure 30 within the plane of the substrate 10 (in other words, within 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 represents 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 (the light intensity distribution of the assumed light source). However, it is preferable that the light intensity distribution is a pupil function that represents a Gaussian distribution, and it is more preferable that the light intensity distribution is a pupil function that represents 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 embodiments, the explanation will be given on the assumption that the pupil function is a homogeneous pupil function.

[0025] Graph L1 in Figure 4 shows an example of a homogeneous pupil function. The x1y1 plane in Figure 4 is the plane on which the optical aperture is drawn, and the z1 axis represents 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), while the light intensity in other areas is zero. Note that the optical aperture is not necessarily limited to a circle, 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 plane is represented by, for example, a Sinc function. Therefore, in this embodiment, the phase distribution (i.e., vibration waveform) of the primary structure 30 is represented by a Sinc function as shown in Figures 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 mathematical formulas (1) and (2). In mathematical 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 to be a pupil function, the amplitude distribution of light transmitted through (or reflected from) the optical body 1 can be considered to correspond 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 formed by combining the above-mentioned primary structures 30, it can be considered that the light (beam of light) transmitted through the optical body 1 has an amplitude distribution corresponding to the above-mentioned homogeneous pupil function. For this reason, the primary structure 30 has a phase distribution corresponding 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 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 light incident on the optical body 1 is λ s ~λ e When the amplitude A fluctuates within a range of μm (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 means the primary structure 30 at the center point 31 determined m-th in the process of determining the position of the center point 31, which will be described later.

[0032]

number

[0033] In equation (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 equation (3), the wavelength is λ s ~λ e It is possible to diffuse light with high uniformity for any incident light with a diameter of (μm).

[0034] The composite structure 20 has a shape formed by combining a large number of primary structures 30. First, a method for synthesizing the primary structures 30 (a method for fabricating the composite structure 20) will be described with reference to FIGS. 5 and 6. The composite structure 20 is fabricated using 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 multiple pixels. The shape, size, and real-space size corresponding to one pixel (the so-called resolution) of the x2y2 plane 100 may be set according to the shape, size, etc. of the optical body 1 to be actually fabricated. While the resolution depends on the capabilities of the exposure device, it is preferably set to approximately 0.2 to 0.8 μm / px to improve the accuracy of the composite structure 20. The size of the x2y2 plane 100 is determined by the number of pixels constituting the x2y2 plane 100. For example, if the x2y2 plane 100 is rectangular, the size of the x2y2 plane 100 is determined by multiplying the number of pixels on the long side 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 existence probability P (%). The in-plane existence probability P is set by the operator (the 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 any position on the x2y2 plane 100.

[0036] Next, as shown in Figure 6, the primary structures 30 are placed at each center point 31 according to the amplitude A, period Λ, existence area T, and periodic perturbation δ of the primary structures 30, which have been set in advance by the worker. Here, the existence area 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 the specific value of the period Λ for each primary structure 30 is randomly determined within the range of the periodic perturbation. When the periodic perturbation is β%, the period Λ of each primary structure 30 is 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 the 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 creates a pattern image. The height z2 of the composite structure 20 in the pattern image is expressed, for example, by the gradation of pixel colors. 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: The z2 axis is defined in the height (thickness) direction of the substrate 10, and the direction away from the substrate 10 is 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 and minimum values ​​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 will be further improved.

[0039] Then, a master (having the 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 on the optical body 1. Light transmitted through or reflected by such an optical body 1 has a highly 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 a screen onto which 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., a 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., a type of comparative example of this embodiment). The horizontal axis in FIGS. 32 and 33 indicates position on the screen, and the vertical axis indicates 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 an area with high amplitude frequency. In a luminance profile in which the peak ratio value is 2.5 or less, the luminance is uniform 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 zeroth-order light or the peak P1 of the first-order light is extremely large, impairing the uniform light distribution.

[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] When diffused light from a diffuser is irradiated onto a screen, macroscopic mottled patterns (so-called macroscopic mottling) may be observed within the irradiated area of ​​the screen. Such mottled patterns are one of the causes of impairing the uniform light distribution. As verified in the examples described below, 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 of a two-dimensional optical aperture with a uniform light intensity distribution (i.e., a homogeneous pupil function). This allows the optical body 1 to emit diffused light with high efficiency and high uniform light distribution (with little macroscopic spotting) for various incident light beams (e.g., collimated light or other types of light). Note that 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 (the 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 believed that the same effect as described above can be obtained in this case as well.

[0044] The diffused light emitted from such optical body 1 has very little macroscopic spots, good visibility, and high uniformity. Therefore, 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, by controlling the light distribution component of reflected light with respect to incident light that enters composite structure 20 of optical body 1, or by controlling the light distribution component of the transmitted light beam, diffusion with a uniform energy distribution and little macroscopic spots is realized.

[0045] Sheet film bodies or various devices to which the optical body 1 is applied have excellent functions of uniformly diffusing light and expanding optical apertures due to the high uniformity of 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, medical measurement 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 the pattern image, first, an electronic computer capable of creating the pattern image is prepared. The electronic computer has, as its hardware configuration, a CPU (Central Processing Unit, i.e., processor), RAM (Random Access Memory), 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 electronic computer, in particular programs necessary for creating the pattern image, etc. The CPU reads 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. The concave and convex portions of the primary structure 30 may also be reversed. In this case, the operator inputs information indicating that the concave and convex portions of the primary structure 30 are to be reversed into the electronic computer.

[0048] Next, the computer creates a pattern image based on the information provided by the operator. First, the computer sets an x2y2 plane 100 in virtual space, as shown in Figure 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 computer scans the x2y2 plane 100 pixel by pixel in the x2 direction (direction of arrow P). Then, for each pixel, it determines whether or not to place the center point 31 of the primary structure 30 based on the in-plane existence probability P (%). 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 the entire x2y2 plane 100 is scanned. 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 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 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. In other words, a pattern image is created. Note that the synthesis method is not limited to simple summation, and other synthesis methods may also be used. Note that the processing of step S100 may be performed at any timing before the processing of step S105 is performed.

[0051] Next, in step S101, the worker cleans the 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 cleaned substrate. Examples of 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 thickness may be, for example, approximately 2 to 15 μm. The resist formation process is achieved 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 using various known exposure methods, such as exposure using a grayscale mask or the like (including multiple exposures using multiple grayscale masks superimposed on each other), 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 exposure device. The device performs exposure based on the pattern image. The laser wavelength may be selected as appropriate, and examples include 405 nm, 436 nm, and the like. These devices expose the resist based on the pattern image. Exposure is performed pixel by pixel according to the resolution.

[0054] In step S107, the operator develops the exposed substrate with an alkali. Examples of developers 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 matrix. For example, the worker may prepare a master matrix (glass master, etc.) by etching the substrate after alkaline development (for example, glass etching using CF4 gas, Ar gas, etc.). Alternatively, the worker may perform Ni sputtering (for example, equivalent to 20 to 60 nm) or electroforming pretreatment on the substrate after alkaline development, and then perform Ni electroforming to peel off the coating from the substrate. This coating may then be used as the master matrix (metal master). The electroforming pretreatment is performed by immersing the developed substrate in a Ni bath such as a Ni sulfamate bath. The thickness of the coating may be selected as appropriate. On the surface of the master matrix, irregularities having the same shape as the synthetic structure 20 are formed.

[0056] In step S113, the worker uses the completed master matrix to create a mold such as a soft mold. For example, an uncured curable resin is applied to a substrate, and the unevenness of the master matrix is ​​pressed against the uncured curable resin layer. In this state, the curable resin is cured. The soft mold is created 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 surface of the soft mold is formed with unevenness that is the inverted shape of the composite structure 20.

[0057] In step S115, the worker performs a transfer process on the substrate 10. For example, the worker applies uncured curable resin to the substrate 10 and presses the irregularities of the mold onto the uncured curable resin layer. In this state, the curable resin is cured. 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 needed. The optical body 1 is produced by the above steps. It is also possible to omit the soft mold production step and produce the optical body 1 directly from the master master. In this case, irregularities that are the inverted shape of the composite structure 20 are 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 the optical body 1 may be applied to any field that requires uniform light distribution of diffused light. The optical body 1 may be applied to, for example, lighting devices, image display devices, optical measurement devices, medical measurement devices, and ultraviolet light application devices. 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 light source is not particularly limited. The light source may be one that emits collimated light or telecentric light including parallel chief rays, or may be another type of light source. [Example]

[0060] <1. Examples A to E> In Examples A to E, optical bodies 1 were actually produced and their 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, an optical body 1 was fabricated according to the manufacturing method described above. Briefly, the substrate after alkali development was subjected to electroforming pretreatment, followed by Ni electroforming, and the coated body was peeled off from the substrate. This coated body was then used as a master (metal master). The pattern image had a rectangular shape, a size of 200 × 200 px (rectangle), a resolution of 0.8 μm / px, an in-plane existence probability P of 0.1%, an amplitude A of a value satisfying the above-mentioned formula (3) (the wavelength of light was 532 nm), a period Λ of 5 μm, an existence region T of 50 Λ, and a periodic perturbation δ of 10%. The refractive indexes of the substrate 10 and the composite structure layer 15 were 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 depicted in eight gradations. As is clear from FIG. 8, the concave and convex portions of the composite structure 20 are randomly distributed within 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 microlenses in a planar view was set to 15 μm, and the diameter was varied by 5% perturbation for each microlens. Furthermore, the radius of curvature of each microlens was set to 8 μm, and the radius of curvature was varied by 5% perturbation for each microlens. Note that the pattern image in FIG. 30 is a tiled version of the same pattern image in a 2 × 2 array. As is clear from this example, regions A with similar concave and convex shapes are scattered throughout. Such regions A can cause 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 Co., Ltd. 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 within a 20 mm aperture was measured. The average value was measured for each angle of incidence of the diffused light into the aperture, and this was taken as the luminance value. The results are shown in Figure 9. The horizontal axis represents the angle of incidence of the diffused light, and the vertical axis represents luminance. As is clear from this example, a distribution with high uniformity of light distribution was 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 substrate 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. Furthermore, since the composite structure 20 is formed by combining primary structures 30 that are randomly arranged within the plane of the substrate 10, the height z2 varies randomly.

[0065] The inventor evaluated the light distribution characteristics of the optical body 1 through simulation. Siemens Virtual-Lab software was used for the simulation. The simulation conditions were as follows: a collimated light source with a diameter of 0.8 mm was used as the light source, and the wavelength was 532 nm (plus 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 composite structure layer 15 was 1.5. 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 onto 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 onto 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 was calculated based on the luminance distribution of this projected image. It can be seen that in all examples the diffused light has high uniformity.

[0066] (1-2. Example B) In Example B, an 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, the unevenness of the composite structure 20 is randomly distributed within the pattern image.

[0067] Fig. 15 shows the light distribution characteristics measured using Mini-Diff. Example B also provides a highly uniform light distribution. Fig. 16 shows a confocal microscope image of the composite structure 20 of the optical body 1. As is clear from Fig. 16, 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 the image projected onto the screen when light with a wavelength of 532 nm is incident on optical body 1, and Figure 16 shows the image projected onto the screen when combined light with wavelengths of 473 nm, 532 nm, and 635 nm is incident on optical body 1. In both examples, it can be seen that the diffused light has high homogeneity.

[0069] (1-3. Example C) In Example C, an 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, the unevenness of the composite structure 20 is randomly distributed within the pattern image.

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

[0071] (1-4. Example D) In Example D, optical body 1 was fabricated under the same conditions as Example A, except that the in-plane existence probability P was set to 0.6% and the period Λ was set to 4 μm. The light distribution characteristics were evaluated using the same method as Example A. FIG. 22 shows the light distribution characteristics measured using Mini-Diff. Example D also achieved a highly uniform light distribution. FIG. 23 shows a confocal microscope image of composite structure 20 of optical body 1. As is clear from FIG. 23, composite structure 20 is formed on the surface of optical body 1. FIG. 24 shows a projected image obtained when diffused light obtained under the same conditions as FIG. 22 was irradiated onto a screen. The distance from 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 was incident on optical body 1. As is clear from FIGS. 24 and 25, the diffused light exhibits high uniformity.

[0072] (1-5. Example E) In Example E, optical body 1 was fabricated under the same conditions as Example A, except that the in-plane existence probability P was set to 0.5%, and the light distribution characteristics were evaluated using the same method as Example A. FIG. 26 shows the light distribution characteristics measured using Mini-Diff. Example E also achieved a highly uniform light distribution. FIG. 27 shows a confocal microscope image of composite structure 20 of optical body 1. As is clear from FIG. 27, composite structure 20 is formed on the surface of optical body 1. FIG. 28 shows a projected image obtained when diffused light obtained under the same conditions as FIG. 26 was irradiated onto a screen. The distance from optical body 1 to the screen was 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 was incident on optical body 1. As is clear from FIGS. 28 and 29, the diffused light exhibits 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, the light distribution characteristics of optical body 1 were evaluated by simulation, varying the in-plane existence probability P, period Λ, existence region T, and period perturbation δ, to investigate the effects of these parameters on the light distribution characteristics. The specific simulation method was the same as in Example A. The parameters and results for each Example and Comparative Example are shown in Tables 1 to 8. In Tables 1 to 8, "Good Light Distribution" indicates a state in which no ring light or mottled pattern was observed (high homogeneity of the diffused light). In other words, it indicates that diffused light similar to that shown in Figure 12 was observed. "Very Faint Ring Light" indicates that an extremely faint ring light was observed, but the peak ratio value was 2.5 or less. "Ring Light" indicates that a ring light was clearly observed, and the peak ratio value was greater than 2.5. An example of ring light is shown in Figure 31. The "Judgment" was "Good" if the peak ratio value was 2.5 or less, and "NG" if the peak ratio value was 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, 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 at certain values. As is clear from Examples 16 to 34 and Comparative Examples 6 to 16, 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 embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that a person skilled in the art to which the present invention pertains can conceive of various modifications and alterations within the scope of the technical ideas set forth in the claims, and it is understood that these also naturally fall within 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 Fourier transforming 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 part 33 Recess

Claims

1. An optical body in which a composite structure having a shape formed by combining a plurality of main structures is continuously developed within the plane of a base material, The phase distribution in the 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, and is represented by a Sinc function, An optical body, wherein the pupil function is a pupil function whose light intensity distribution indicates a Gaussian distribution.

2. 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, 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 The optical body according to claim 1 , characterized in that it has a shape formed on a flat surface.

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

4. 4. The optical body 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.

5. The optical body according to any one of claims 1 to 4, characterized in that the period Λ of the phase distribution of the primary structure satisfies the following condition 1. Condition 1 Λ≧5μm

6. 5. The optical body according to claim 1, wherein an in-plane existence probability P and a period Λ of the primary structures satisfy the following condition 2. Condition 2 P≧0.3% and Λ≧3 μm

7. 5. The optical body according to claim 1, wherein an in-plane existence probability P, an existence region T, a period Λ, and a periodic perturbation δ of the primary structures satisfy the following condition 3. 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.

8. 8. An illumination device comprising the optical body according to claim 1 disposed on a surface of a light source.

9. 8. An image display device, comprising: an optical body according to claim 1 disposed between a light source and a display unit.

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