JP2017037106A - Optical member, light source device and image display device having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical member capable of increasing use efficiency of light of a light source with a compact configuration, and an image display device having the optical member.SOLUTION: The optical member includes a substrate 1 and a phosphor part 2 disposed on the substrate and emitting fluorescent light by irradiation with excitation light. The phosphor part has a rugged surface comprising a plurality of convex portions and a plurality of concave portions reflecting the excitation light. The profile of the rugged surface satisfies a conditional formulae of 0.5≤√(S/N)<2.5 [μm] and 0.5≤<H>≤5.0 [μm], where S represents a measurement area where the profile of the rugged surface is measured, N represents the number of convex portions in the measurement area, and <H> represents an average height of the convex portions.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a light source, and more particularly to a light source of an image display device.

  In recent years, a light source device combining a laser and a phosphor is known as a light source of an image display device that projects a high-luminance image.

  For example, in Patent Document 1, light from a laser light source is guided by a dichroic mirror to a phosphor on a color wheel or a diffuser for blue light, and the image display element is irradiated with diffused light of emission and excitation light from the phosphor. A light source device is disclosed. Here, in patent document 1, since the diffused light of the blue laser light scattered by the phosphor reduces the color purity of the image due to the fluorescence emitted from the phosphor, a light shielding wheel for cutting blue is prepared. And the structure which improves a color purity by controlling rotation of a fluorescent wheel and a light-shielding wheel is proposed.

  Patent Document 2 discloses a method of forming an uneven shape having a structural period of 10 μm to 100 μm on the phosphor surface in order to improve the light utilization efficiency of the phosphor.

JP 2011-128522 A JP 2012-68465 A

  In Patent Document 1, a region where blue laser light is diffusely reflected on a color wheel and used as blue light and a light emitting region of a phosphor are arranged separately. However, if the area of the color wheel is made only of the phosphor and the diffused light of the excitation light by the phosphor is used as the light source, the light use efficiency is increased. In particular, the above configuration is advantageous in the case of a three-plate projection type image display apparatus using red, green, and blue as the image display elements. In that case, if the diffusion level of the phosphor surface or the internally scattered light is low, the amount of light is insufficient when the diffused light from the phosphor is used.

  Further, Patent Document 2 uses a surface uneven structure on the phosphor surface, but does not mention the scattered light of the laser light source incident on the phosphor. Therefore, it is difficult to secure sufficient luminance for each color while maintaining the dimensions of the optical system.

  The present invention provides an optical member, a light source device, and an image display device using the optical member that can increase the light use efficiency of the light source with a compact configuration.

  An optical member according to one aspect of the present invention includes a substrate and a phosphor portion that is provided on the substrate and emits fluorescence when irradiated with excitation light. The phosphor portion has an uneven surface composed of a plurality of convex portions and a plurality of concave portions that reflect the excitation light. The shape of the concavo-convex surface is 0.5 when the measurement area for measuring the shape of the concavo-convex surface is S, the number of convex portions in the measurement area is N, and the average height of the convex portions is <H>. ≦ √ (S / N) <2.5 [μm] and 0.5 ≦ <H> ≦ 5.0 [μm] are satisfied.

  A light source device according to another aspect of the present invention includes a substrate, an optical member that is provided on the substrate and emits fluorescence when irradiated with excitation light, and excitation that irradiates the phosphor with excitation light. A light source. The phosphor portion has an uneven surface composed of a plurality of convex portions and a plurality of concave portions that reflect the excitation light. The shape of the concavo-convex surface is 0.5 when the measurement area for measuring the shape of the concavo-convex surface is S, the number of convex portions in the measurement area is N, and the average height of the convex portions is <H>. ≦ √ (S / N) <2.5 [μm] and 0.5 ≦ <H> ≦ 5.0 [μm] are satisfied.

  ADVANTAGE OF THE INVENTION According to this invention, the light utilization efficiency of a light source can be improved with a compact structure.

1 is a schematic configuration diagram of a light source device in an embodiment of the present invention. It is a figure which shows the structure of the phosphor member in embodiment of this invention. It is sectional drawing of the surface layer in embodiment of this invention. It is a figure which shows the characteristic of the amount of reflective diffusion and scattering angles in embodiment of this invention. It is a figure which shows the average height and average period of uneven | corrugated shape in embodiment of this invention. It is a figure which shows the structural example of the phosphor member in Example 1 and Example 2 of this invention. It is sectional drawing of the surface layer of Example 1 and a comparative example. It is a figure which shows the characteristic of the amount of reflection diffusion of Example 1 and a comparative example, and a scattering angle. FIG. 5 is a schematic configuration diagram of a projection type image display device according to a second embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each figure, the same members are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a schematic diagram showing a simple configuration of a light source device 100 of the present invention. The light source device 100 includes a laser light source 10, an optical system 12, a dichroic mirror 13, a condensing optical system 15, and a phosphor member 16 (optical member).

  First, the excitation light 11 emitted from the laser light source 10 becomes substantially parallel light by the optical system 12 and enters the dichroic mirror 13. The dichroic mirror 13 includes a first region 14a and a second region 14b, and the first region 14a has a characteristic of transmitting light having a wavelength of a laser light source. Therefore, the excitation light 11 passes through the dichroic mirror 13.

  The excitation light 11 that has passed through the dichroic mirror 13 is condensed by the condensing optical system 15 and applied to the phosphor member 16. The phosphor layer 2 of the phosphor member 16 absorbs part of the excitation light 11 and emits light (fluorescence) having a wavelength longer than that of the excitation light 11. The excitation light 11 that is not absorbed by the phosphor layer 2 is diffusely reflected as diffused light by the surface reflection / diffusion and internal scattering of the phosphor member 16.

  In FIG. 1, the diffuse reflected light of the excitation light 11 is shown as 17 La, 17 Lb, and 17 Lc, and the diffused light emission (fluorescence) of the phosphor layer 2 is shown as a dotted line by 17 Pa, 17 Pb, and 17 Pc. Hereinafter, unless otherwise specified, the diffuse reflection light of the excitation light 11 and the diffuse light emission of the phosphor layer 2 are collectively referred to as diffuse light. Here, the difference between the subscripts a, b, and c represents the difference in diffusion angle. 17Pb and 17Lb correspond to components at a low angle with respect to the surface normal, and 17Lc, 17Pc, 17La and 17Pa correspond to components at a high angle with respect to the surface normal.

  Each diffused light from the phosphor member 16 reenters the dichroic mirror 13 by the condensing optical system 15. Here, both the first region 14 a and the second region 14 b of the dichroic mirror 13 have reflection characteristics with respect to the fluorescence wavelength of the phosphor layer 2. Therefore, the diffused lights 17Pa, 17Pb, and 17Pc are reflected by the dichroic mirror 13 and are emitted from the emission unit 18 to the outside.

  On the other hand, for the wavelength of the excitation light 11, the second region 14b has reflection characteristics, but the first region 14a has transmission characteristics. Therefore, the components 17La and 17Lc diffused at a high angle are reflected by the second region 14b and emitted from the emitting portion 18 similarly to the diffused light of the phosphor layer 2, but the component 17Lb diffused at a low angle is The light passes through the first region 14a and returns to the laser light source 10 side.

  The amount of the diffused light 17Lb of the excitation light 11 returning to the laser light source 10 side depends on the diffusion angle, the shape of the first region 14a and the second region 14b, and the area ratio. For the above reasons, it is desirable to make the area of the first region 14a as small as possible and the area of the second region 14b as large as possible, but in actuality, it is realized with the configuration of the laser light source 10 and the size that the light source device 100 can take. It is difficult to do. Therefore, also from the relationship with the condensing optical system 15, most of the components that diffuse at a low angle of about 10 deg to 20 deg return to the laser light source 10 side.

  That is, when used in the configuration of FIG. 1, 17 Lb is lost among components that are specularly reflected on the surface of the phosphor layer or the like, or surface scattered light or reflected diffused light, so that the light use efficiency of the light source device 100 is increased. Therefore, it is necessary to reduce the low angle component of the light from the phosphor member 16. Therefore, in the light source device 100 of the present invention, the angular characteristic of the diffuse reflection of the excitation light 11 is controlled by making the surface of the phosphor member 16 have an uneven shape (uneven surface).

FIG. 2 is a schematic view showing an example of the surface shape of the phosphor member 16. Here, a structure in which the phosphor layer 2 and the surface layer 3 are sequentially formed on the substrate 1 as the phosphor member 16 is shown. In the present embodiment, the surface layer 3 is formed with a concavo-convex shape having a minute hemispherical shape, and excitation light is diffused and reflected at a high angle by the surface layer 3. Moreover, the refractive index difference at the interface between the surface layer 3 and the phosphor layer 2 is small, and light reflection and scattering at the surface of the phosphor layer 2 are suppressed. At this time, the light emission component from the fluorescence is also scattered by the surface layer 3, but the light emission from the fluorescence originally diffuses isotropically with respect to the angle, so that the influence of the scattering by the surface layer 3 is small. Here, when the number of convex portions in a region within a certain area S (measurement area) is N and the average height of the convex portions is <H>, the surface layer 3 is as follows. Satisfies the conditional expression.
0.5 ≦ √ (S / N) <2.5 [μm] (1)
0.5 ≦ <H> ≦ 5.0 [μm] (2)
√ (S / N) is an approximate amount of the period of the concavo-convex shape in the area S in the xy plane, and the conditional expression (1) falls within the range of the average period of the concavo-convex shape from about 0.5 μm to 2.5 μm. Indicates that it is necessary. Conditional expression (2) indicates that the average height <H> of the concavo-convex shape is 0.5 μm or more and 5.0 μm or less. Here, when the area S is too small, the influence of variation is large in the measurement of the period of the concavo-convex shape.

  FIG. 3A to FIG. 3D show an example of a cross-sectional shape at a certain height of the surface layer 3 shown in FIG. FIGS. 3 (a) to 3 (d) each represent a 40-um square region, and show the case where the average particle diameter <φ> of the hemisphere is 1 um, 2 um, 4 um, and 6 um. Also, each white sphere shows a cross section of the hemisphere in FIG. 2, but the size and position of each sphere have some variation. Table 1 shows the average particle diameter N and the values of the conditional expressions (1) and (2). FIG. 4 shows the result of plotting the reflection intensity of the light incident on each structure at this time against the diffusion angle. The vertical axis in FIG. 4 indicates the amount of reflected diffusion, and the horizontal axis indicates the scattering angle [deg]. In FIG. 4, the solid line corresponds to FIG. 3D, the dotted line corresponds to FIG. 3C, the broken line corresponds to FIG. 3B, and the double line corresponds to FIG. The double lines and broken lines corresponding to FIGS. 3A and 3B that satisfy the conditional expressions (1) and (2) are shown in FIGS. 3C and 3D when the scattering angle is high. ) Shows a higher reflection diffusion amount than the dotted and solid lines.

  Specifically, Table 2 shows the total reflection diffusion amount in a certain angle range in each structure of FIG. i represents a reflection diffusion amount in a range from 0 deg to 15 deg, and ii represents a reflection diffusion amount from 15 deg to 60 deg. 60 deg is used as a guide for the angle that can be captured by the condensing optical system 15. iii represents the sum of reflection diffusion amounts in the range of 0 deg to 80 deg, and ii / iii represents the ratio of ii to the total reflection amount iii. The intensity expected to be taken in as 17La or 17Lc is 25.5% in the case where the average period is 5 μm, but increases to 67.5% in the case where the average period is 1 μm. Actually, it contributes not only to the surface reflection but also to the diffusion component inside the phosphor, but the structure shown in FIGS. 3 (a) and 3 (b) improves the diffusion characteristics and causes a loss of the diffusion component of the excitation light. Can be suppressed.

  From the above results, it can be seen that the uneven particle size is a parameter that greatly affects the diffusion characteristics of FIG. More specifically, the diffusion characteristics are influenced by the period of the irregular particle arrangement and the height of the irregular shape, and are influenced by diffraction derived from the periodic structure and scattering (Mie scattering) characteristics derived from minute irregularities. Is done. By making the concavo-convex shape within the range of the conditional expression (1), the generation order of diffraction due to the regular periodic structure can be suppressed to a low order (first to second order), and along with this, the light wave toward the concavo-convex shape slope direction Therefore, the high angle scattering component increases. Furthermore, since the light diffusion amount becomes broad with respect to the angle due to the random arrangement of irregularities, local concentration of luminance can be suppressed and an angular distribution as shown in FIG. 4 can be obtained. As a result, low-angle scattering components are reduced, and the amount of light of 17 Lb in FIG.

  As a method for obtaining a detailed average period for the concavo-convex shape in FIG. 3, for example, in a cross section X in FIG. 5A, the closest distance between the central positions of the concavo-convex portions as shown in FIG. There is a method of obtaining P1, P2,..., Pi and obtaining an average distance (average period) <ri>. Alternatively, a method of obtaining the radial distribution function D (r) as the particle density with respect to the distance r from the center coordinate of each sphere on the three-dimensional distribution may be used. Although a value obtained from these values may be used as the average period, obtaining <ri> and D (r) is not easy because it includes evaluation of the center coordinates of the concavo-convex shape and statistical processing. As a method for more simply obtaining the average period of the concavo-convex shape, when the area of the region of FIG. 3 is S, the area S is divided by the number of concavo-convex shapes in the area S (here, the number of hemispherical particles) N, The average period can be estimated by taking the square root.

As a method for calculating N, there is a method in which a three-dimensional surface shape is measured and acquired (a method will be described later), and then the uneven shape is counted visually. In addition, a cross-sectional image is acquired at the position of the average height of the surface shape obtained by measurement, or (maximum height-minimum height) / 2, and binarized into the uneven shape region and the other region To do. For example, when the uneven material region is black and the other region is white, it can be obtained by counting the number of regions occupied by black. Furthermore, N may be calculated by counting the number of microspheres when the shape of each black area of the image is approximated by microspheres. Such a measurement method is averaged and accuracy increases as the area of the area S to be measured is wider. For this reason, the size of the area S is assumed to be at least a side of 10 μm or more, that is, a region of 100 μm ² or more. In the present invention, this √ (S / N) is regarded as an apparent average period, and a desired diffusion characteristic is obtained by configuring the average period to be 0.5 μm or more and 2.5 μm or less. When the average period exceeds 2.5 μm, higher-order diffraction increases, and as shown in FIG. 4, the intensity of low-order light increases, so that the amount of light returning to the light source increases and the amount of light in the desired angular region is increased. Decrease. The region below 0.5 μm is not desirable because not only the structure period becomes finer and the manufacturing difficulty increases, but also approaches the diffraction limit at the excitation light source wavelength of the phosphor. Therefore, √ (S / N) is desirably 0.5 μm or more and 2.5 μm or less.

  Further, the height of the concavo-convex shape is not desirable because the height of the concavo-convex shape is close to the reflection characteristic from a planar shape having no structure. The average height <H> of the concavo-convex shape is such that when the heights H1, H2,..., Hi of each structure are defined as shown in FIG. It is desirable to be within the range of 5.0 μm. As a specific calculation method, the maximum value of the convex and concave portions extracted at the time of counting the average period may be measured and averaged to obtain the average height <H>. However, when there is a residual in the low part of the concavo-convex shape, it is necessary to measure and average the height of the minimum value of the concave part. For example, the height (vertex position) of the peak portion of the convex-shaped portion of the concave-convex shape extracted from the binary image used in the average period count, and the concave-convex concave shape in the vicinity of the vertex portion (within one to two cycles) The height (bottom surface position) of the bottom part of each part is measured and averaged, and the difference is defined as the average height <H>. Here, the height is a position in the normal direction from the substrate 1 toward the phosphor layer 2.

  At this time, if <H> exceeds 5.0 μm, the aspect ratio of the structure increases, adverse effects such as a decrease in the strength of the concavo-convex shape increase, and the manufacturing difficulty increases, which is not desirable. On the other hand, when the thickness is less than 0.5 μm, the effect of the present invention is lowered because the characteristics of the flat surface are approached.

  Furthermore, in a periodic structure several times the wavelength, in addition to the wave optical effect, the reflection effect by the uneven surface is superimposed. Therefore, when the average period is √ (S / N) and the average height is <H>, √ (S / N) / <H> corresponding to the aspect ratio of the structure is 0.5 or more and 2 or less. Is desirable. In the case of 0.5 or less, the reflection angle of the light beam becomes too high. On the other hand, at 2.0 or more, the component of multiple reflection and the component transmitted to the inside increase. However, as can be seen from FIG. 3 and FIG. 4, if only the geometrical action is considered, there is no difference between FIG. 3 (a) and FIG. 3 (d). The condition regarding √ (S / N) / <H> is a condition for further strengthening light waves in a desired angle region after satisfying the expressions (1) and (2).

  Various methods can be arbitrarily selected as the method for measuring the surface shape. If a method using AFM or an interference measurement method, a 3D measurement device using a laser microscope, or the like is used, the surface shape can be measured without being destroyed. Further, a method such as a cross-sectional SEM may be used. The obtained surface shape is subjected to frequency filtering to some extent according to the measurement magnification, scan range, and resolution. In addition, an error may occur due to element deflection or undulation during measurement. Since these values are irrelevant to the conditional expression of the present invention, they are eliminated by performing a predetermined process.

  In general, not only the uneven shape of the surface layer 3 but also various surface states including large and small undulations affect the size and shape that can be identified as the uneven shape within the area S. In the present invention, an in-plane dimension having a structural period of 100 nm to 10 μm and a structural height in the range of 0.1 μm to 10.0 μm sufficiently including the conditional expression (1) that defines the effect of the invention is an uneven shape. Define.

  For a period finer than the above range, it is desirable to perform a flattening process by averaging or the like. In a period of 10 μm or more, it is desirable to obtain <H> and √ (S / N) after correcting the height of the waviness. When the uneven density density locally exists on a scale of 100 um or more, it is desirable to use the average value of <H> and √ (S / N) in different regions of about 3 to 5 regions.

  Moreover, since the average height <H> is an amount corresponding to the average height: Rc of the roughness curve element of JIS standard, the value of Rc may be used in the measurement. Since √ (S / N) is an amount corresponding to the average length Rsm of the JIS standard surface roughness curve element, the value of Rsm may be used in the measurement. In that case, 10 or more line roughness measurements are performed in two orthogonal directions within the area S, and the average value is calculated. Furthermore, the surface shape can be decomposed into frequency components by subjecting the acquired two-dimensional height image of the surface shape (for example, a bmp image obtained by dividing the height component to 255 values).

  By cutting off frequency components of 100 nm or less or 10 μm or more and then obtaining the average value from the signal intensity and the frequency component, the average period can be obtained with higher accuracy. These data are more preferably obtained more accurately than the method used in the description of the above formulas (1) and (2), but the effects of the present invention can be achieved even with the above method.

  In the following description, the size of the uneven shape (average structure width) is <φ>, and the average period of the uneven shape is <P>. When the irregular shape is perfectly ordered, <φ> and <P> match. In that case, the reflected diffused light is concentrated at a specific angle determined by diffraction. Even in such a case, if the diffraction angle does not reflect and diffuse in the range of the first region of the dichroic mirror, a decrease in utilization efficiency can be suppressed. However, the diffracted light from a highly uniform periodic structure has a narrow angular distribution, and when used for illumination of a liquid crystal projector or the like, there may be luminance unevenness or color unevenness in the screen. Therefore, it is desirable that the concavo-convex arrangement of the surface layer 3 is not a complete periodic structure but has randomness. If the arrangement is disturbed due to random arrangement or the like, the number of the concavo-convex structures in the area S increases and decreases, so generally <P> and <φ> are different. The difference between the average period <P> and the average structure width <φ> is used as an evaluation measure of randomness, and the difference | <P> in a region of 10 <P> ^ 2 or less where the area S is 10 times the period. It is desirable to have a structure in which − <φ> |

  Various methods can be applied as a method for manufacturing the structure of the present invention. First, regarding the shape of the concavo-convex structure, not only a hemisphere but also a sphere, an ellipse (hemisphere), a columnar shape, a polygonal shape, a weight shape, a cone shape, a trapezoid shape, or a combination thereof can be used according to the manufacturing method. For example, in the case where an uneven shape is formed on the surface of the phosphor layer, a method using phosphor fine particles can be considered. The particle size distribution of the polygonal phosphor fine particles is previously set in a range of 0.5 μm to 2 μm, and is fixed by sintering or a binder. At that time, the upper half of the phosphor fine particles on the outermost surface is exposed, or coating or film formation is performed with a thin binder so that the particle shape remains on the surface. By this method, the surface shape can be obtained according to the structure of the phosphor fine particles as shown in the figure, and the conditional expressions (1) and (2) can be satisfied by controlling the particle size of the phosphor fine particles. However, the particle size of the phosphor fine particles may depend on the emission efficiency of the fluorescence, etc. If the particle size is reduced, the efficiency may decrease due to an increase in the ratio of surface defects.

  As another method, there is a method in which fine particles (silica fine particles, etc.) having a particle size of about 0.5 μm to 2.0 μm are coated on the surface. In addition to the application, for example, the surface layer 3 may be formed on the phosphor layer 2 by molding.

  As the uneven material of the surface layer 3, a binder for fixing the phosphor fine particles to the phosphor layer 2, a UV curable resin, a thermosetting resin, and other inorganic sol-gel materials may be used. Further, the surface layer 3 is not necessarily formed on the surface of the phosphor layer 2 and may be formed integrally with the phosphor layer 2 as a phosphor portion.

  Furthermore, an uneven shape may be produced on another substrate instead of the surface layer 3, and the uneven shape of the substrate may be arranged near the surface of the phosphor layer. In this case, the same effect can be expected. However, as the uneven surface is further away from the surface of the phosphor layer 2, the area on which the excitation light on the surface of the phosphor layer 2 is collected increases due to diffusion, and the illumination efficiency may decrease.

  Further, the magnitude of the surface reflectance depends on the refractive index of the material of the surface layer 3, but can be controlled to some extent by coating. For example, the surface reflection component can be increased by attaching a film having a refractive index higher than that of the surface layer 3 to the upper surface of the surface layer 3 manufactured by the above-described method with an optical film thickness of λ / 4. . Thus, the ratio between the surface diffuse reflection component of the excitation light that reaches the phosphor layer 2 and the transmission component that reaches the phosphor layer 2 and is used for light emission is the color gamut necessary for the light source device. It can be optimized as appropriate according to the application such as balance and brightness. The above-described manufacturing method is merely an example and does not limit the effect of the present invention, and an optimal manufacturing method and configuration may be selected according to the application.

  Below, the light source device 100 of Example 1 of this invention is demonstrated. FIG. 1 shows a schematic configuration diagram of a light source device 100 of the present embodiment. The element arrangement of the light source device 100 is as described above, and a description thereof is omitted.

  In the light source device 100 of the present embodiment, a high-luminance light source is realized by exciting a plurality of blue laser diodes having a wavelength of 450 nm as excitation light sources. Moreover, the phosphor layer 2 of the present embodiment absorbs light having a wavelength of 450 nm and uniformly diffuses red and green light mainly in the vicinity of the wavelength of 500 to 650 nm as fluorescence. At this time, it has an uneven shape for diffusing the excitation light 11 at the same time, and the excitation light is also reflected and diffused at the same time, so that it is substantially reflected as white light including blue, green and red. Here, the phosphor member 16 including the phosphor layer 2 is formed as shown in FIG. Since the phosphor layer 2 collects and receives strong light from the laser light source, it tends to become high temperature. Therefore, in this embodiment, in order to suppress the temperature rise by shifting the position of the excited phosphor layer 2 in time, the phosphor member 16 can be rotated in the circumferential direction in a wheel shape (disc shape). Form. At this time, the diffused light of the fluorescence and the excitation light is always emitted by forming the phosphor layer 2 in a circular shape around the rotation axis of the wheel, so that the luminance is stably high without any temporal change in luminance. The resulting light source device 100 is provided. The phosphor layer 2 may be formed in an arc shape instead of a circular shape around the rotation axis of the wheel.

  On the surface of the phosphor layer 2, a surface layer 3 is formed as shown in FIG. The surface layer 3 has a substantially hemispherical random uneven shape formed on the surface of the phosphor layer 2. The phosphor layer 2 is composed of phosphor fine particles and a binder. For example, the phosphor layer 2 is formed by applying a material containing phosphor fine particles and a silicone-based resin binder on the metal substrate 1 by a bar coating method or the like and drying and solidifying the material. In this embodiment, the surface layer 3 is obtained by transferring a hemispherical structure having a variation with a standard deviation of 100 nm in the in-plane direction and a particle size of ± 100 nm from a state in which a hemispherical shape having an average diameter of 1 um is arranged in the closest packing. is there. This structure can be manufactured by using photolithography, an electron beam drawing apparatus, or the like. Further, the material of the surface layer 3 is the same as that of the phosphor binder, but is a sol-gel material containing an inorganic material such as silica, or a material such as a thermoplastic resin or an ultraviolet curable resin used in the nanoimprint process. Also good.

  FIG. 7A shows a cross-sectional view in the direction perpendicular to the surface normal with respect to a region having an area S of 10 μm square at a certain height of the surface layer 3 obtained by such a method. Among them, a cross-sectional view along a straight line L is shown in FIG. FIG. 7A corresponds to the cross section at the height average position s in FIG.

  As a comparative example, FIGS. 7 (c) and 7 (d) show a structure obtained by transferring a hemispherical structure with an average diameter of 5 μm, a directional position of 1500 nm, and a standard deviation of a particle diameter of ± 1500 nm as a mold.

  FIGS. 7 (a) to 7 (d) show the three-dimensional shape of the surface layer 3 in a vertical and horizontal range of 40 μm and a height range of ± 2.0 μm using a laser microscope 3D measuring device having a wavelength of 405 nm. The result of having acquired the horizontal cross section in the position s = 500 nm is shown.

  FIG. 8 shows a graph of the reflection diffusion amount and the angular distribution of the present example by a solid line, and shows a similar graph in the structure of the comparative example by a dotted line. Table 3 shows the relationship with the conditional expressions (1) and (2) for the present example and the comparative example, and Table 4 shows the result of comparing the angle distribution of the reflection diffusion amount similar to Table 2. From Table 3, it can be seen that this example satisfies the conditional expressions (1) and (2). Further, from FIG. 8 and Table 4, in particular, the reflection diffusion amount from 15 deg to 60 deg increases from 0.207 to 0.656. Thereby, it turns out that the fluorescent member 16 of a present Example can utilize efficiently the blue light of the diffused light of excitation light.

  Next, a projection type image display apparatus 200 according to the second embodiment of the present invention will be described. FIG. 9 shows a schematic configuration diagram of the projection type image display apparatus 200 of the present embodiment. A description of portions common to the first embodiment will be omitted.

  In the projection type image display apparatus 200, first, the white illumination light 102 composed of the red illumination light 102r, the green illumination light 102g, and the blue illumination light 102b (solid line + dotted line) emitted from the light source device 100 of the first embodiment is converted into the polarization conversion element 103. Pass through. A solid line and a dotted line indicate the optical path of the illumination light. In FIG. 9, for convenience, the illumination light is spatially separated for each color, but in reality, the three lights are not spatially separated at this stage.

  When passing through the polarization conversion element 103, the white illumination light 102 is converted into red illumination light 104r, green illumination light 104g, and blue illumination light 104b aligned in a uniform polarization (solid line). Thereafter, the green illumination light 104 g is then separated from the blue light and the red light by the dichroic mirror 105. The green illumination light 104g passes through the polarization separation element (hereinafter referred to as PBS) 108 and the phase compensation plate 112g and is illuminated on the image display element 111g. That is, the polarization conversion element 103, the dichroic mirror 105, the PBS 108, and the phase compensation plate 112g function as an illumination optical system that guides the green illumination light 104g to the image display element 111g.

  The color-separated red illumination light 104r and blue illumination light 104b pass through the polarizing plate 106 and then enter the color selective phase plate 107. The color selective phase plate 107 has a characteristic that the polarization direction of only the blue light 104b is converted by 90 °. Therefore, while maintaining the polarization state of the red illumination light 104r, the polarization direction of the blue illumination light 104b can be incident on the PBS 109 while being rotated by 90 °. Thereafter, the red illumination light 104r is transmitted through the PBS, and the blue illumination light 104b is reflected by the PBS and transmitted through the phase compensation plates 112r and 112b, respectively, and then is illuminated on the image display elements 111r and 111b. That is, the polarization conversion element 103, the dichroic mirror 105, the PBS 109, the phase compensation plate 112r, or the phase compensation plate 112b function as an illumination optical system that guides the red illumination light 104r and the blue illumination light 104b to the image display elements 111r and 111b, respectively.

  The image display elements 111g, 111b, and 111r each modulate incident light to generate image light. Therefore, the illumination lights 104g, 104b, and 104r of each color are converted into image lights 115g, 115b, and 115r by the image display elements 111g, 111b, and 111r. The image lights 115g, 115b, and 115r are combined by the PBSs 108 and 109 and the combining prism 118, and then projected onto the screen by the projection lens 120 (projection optical system) to form an image.

  Here, the projection type image display apparatus 200 of the present embodiment can achieve both color characteristics and light utilization efficiency by using the light source device 100 of the first embodiment as the light source device.

  As a method of using the light from the laser light source as the diffused light source, various methods other than the method of the present invention are conceivable, for example, the arrangement of the light source for exciting the phosphor and the light source used as the blue light is separated. However, when a light source and a diffusing member are separately arranged, the optical system becomes large and the overall size of the light source device also becomes large. In this case, there is a concern such as an increase in the number of parts. Moreover, since the scattered light on the phosphor surface is lost, it is considered that the light utilization efficiency is reduced accordingly. The configuration of the present invention can provide a projection-type image display device having a high light utilization efficiency while being a compact optical system.

  Although there are various methods other than FIG. 9 as the projection type image display, it is desirable that the light source device 100 has a configuration in which fluorescent light of different wavelengths and diffused light of excitation light can be used simultaneously as illumination light. An image display apparatus having a plurality of image display elements corresponding to display of images of each color is more desirable. In FIG. 9, three reflection type image display elements are used. However, a transmission type image display element may be used.

  As described above, the preferred embodiments of the present invention have been described, but the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the gist thereof.

1 Substrate 2 Phosphor layer 3 Surface layer

Claims (13)

A substrate,
A phosphor portion that is provided on the substrate and emits fluorescence when irradiated with excitation light;
The phosphor portion has an uneven surface composed of a plurality of convex portions and a plurality of concave portions that reflect the excitation light,
As for the shape of the concavo-convex surface, S is a measurement area for measuring the shape of the concavo-convex surface, N is the number of the convex shapes in the measurement area, and <H> is the average height of the convex portions. When
0.5 ≦ √ (S / N) <2.5 [μm]
0.5 ≦ <H> ≦ 5.0 [μm]
An optical member satisfying the following conditional expression:   2. The optical member according to claim 1, wherein the average height of the convex portions is a difference between an average of vertex positions of the plurality of convex portions and an average of bottom positions of the plurality of concave portions. .   The optical member according to claim 1, wherein the plurality of convex-shaped portions are formed of a phosphor that emits fluorescence. The phosphor portion includes a phosphor layer that emits the fluorescence, and fine particles constituting the plurality of convex-shaped portions,
4. The optical member according to claim 1, wherein the fine particles are formed of a material different from that of the phosphor layer and are provided on the phosphor layer. 5.   5. The optical member according to claim 1, wherein an average diameter of the plurality of convex portions is not less than 0.5 μm and not more than 2.5 μm.   The optical member according to claim 1, wherein the plurality of convex portions are formed by molding.   The optical member according to any one of claims 1 to 6, wherein the plurality of convex-shaped portions are formed at random positions on the uneven surface.   The plurality of convex-shaped portions have at least one of a spherical shape, a hemispherical shape, a columnar shape, and a cone shape, according to any one of claims 1 to 7. Optical member. The substrate has a disk shape and is configured to be rotatable in a circumferential direction of the disk shape;
The optical member according to any one of claims 1 to 8, wherein the phosphor portion is formed in a circular shape or an arc shape around a rotation axis of the substrate. An optical member including a substrate and a phosphor portion that emits fluorescence when irradiated with excitation light provided on the substrate;
An excitation light source for irradiating the phosphor part with the excitation light,
The phosphor portion has an uneven surface composed of a plurality of convex portions and a plurality of concave portions that reflect the excitation light,
As for the shape of the concavo-convex surface, S is a measurement area for measuring the shape of the concavo-convex surface, N is the number of the convex shapes in the measurement area, and <H> is the average height of the convex portions. When
0.5 ≦ √ (S / N) <2.5 [μm]
0.5 ≦ <H> ≦ 5.0 [μm]
A light source device satisfying the following conditional expression: The optical path of the excitation light from the excitation light source to the optical member further includes a dichroic mirror disposed obliquely with respect to the optical path,
The light source device according to claim 10, wherein the dichroic mirror guides the excitation light from the excitation light source to the phosphor part and emits the light from the phosphor part to the outside. The dichroic mirror is
A first region that transmits light of the wavelength of the excitation light and reflects light of the wavelength of fluorescence from the phosphor portion;
The light source device according to claim 11, further comprising: a second region that reflects both the light having the wavelength of the excitation light and the light having the wavelength of the fluorescence from the phosphor portion. An image display element that generates an image by modulating incident light; and
The light source device according to any one of claims 10 to 12,
An illumination optical system for illuminating the image display element with light from the light source device;
An image display apparatus comprising: a projection optical system that projects light from the image display element.