WO2016098560A1

WO2016098560A1 - Wavelength conversion member and image formation device

Info

Publication number: WO2016098560A1
Application number: PCT/JP2015/083354
Authority: WO
Inventors: 三森　満; 昌宏今田
Original assignee: コニカミノルタ株式会社
Priority date: 2014-12-15
Filing date: 2015-11-27
Publication date: 2016-06-23

Abstract

Provided are: a wavelength conversion member with which it is possible to improve a light distribution characteristic for the purpose of producing a high quality image; and an image formation device using the same. By using optical elements 106h of a light deflection section 106e to divide a spotlight narrowed to a small diameter by a condenser lens 105, it is possible to condense the light into a relatively thin phosphor layer 106d while reducing each light intensity, and deterioration of the phosphor layer 106d can therefore be suppressed. Furthermore, fluorescence produced from the phosphor layer 106d becomes return light in a scattered state but is refracted by the optical elements 106h of the light deflection section 106e and emitted at an angle close to the incident angle of a light beam incident on the light deflection section 106e. It is therefore possible to restrict expansion of light distribution and emit a parallel light beam by using the low NA condenser lens 105.

Description

Wavelength conversion member and image forming apparatus

The present invention relates to a wavelength conversion member and an image forming apparatus, and more particularly to a wavelength conversion member suitably used for an image forming apparatus such as a small image projection apparatus and an image forming apparatus using the same.

In an image projection apparatus which is a kind of image forming apparatus, a projection image is formed using a liquid crystal panel, a mirror deflection type digital micromirror device (DMD), or the like. As a light source for projecting such an image, Conventionally, discharge lamps have been widely used. However, the discharge lamp has a problem that its life is short and its reliability is low, and there is also a demand for environmental protection.
On the other hand, in recent years, solid-state light sources such as semiconductor lasers and light emitting diodes have been developed, and have been used as light sources for image projection apparatuses.

Here, when forming a projected image, high intensity light of three colors of red, green, and blue is required as the three primary colors of light. For example, as a semiconductor laser, a red laser and a blue laser are high. There is a problem that a sufficiently high-brightness green laser has not yet been put into practical use, whereas a bright one has been put into practical use. Therefore, there is an attempt to create green high-intensity light by converting the wavelength of blue laser light. In addition, wavelength conversion of blue laser light has been performed to create red high-intensity light. For example, Patent Document 1 discloses a fluorescent wheel that excites red light by causing blue laser light to enter the red phosphor layer and excites green light by causing blue laser light to enter the green phosphor layer. ing.

On the other hand, in order to promote downsizing and energy saving of the image projection apparatus, there is a demand to increase the light use efficiency while minimizing the light source itself. In general, as a method of increasing the light use efficiency of the image projection apparatus, there is a method of reducing the Etendue, which is the product of the light emitting area of the light source and the solid angle of the light beam emitted from the light source.

In order to solve such a problem, Patent Document 2 has been devised to improve the light utilization efficiency by providing a fine uneven shape on the surface of the phosphor layer.

JP 2009-277516 A JP 2012-68465 A

Here, in Patent Document 2, a portion (uneven structure) having a hexagonal bottom surface is formed by cutting a part of a plurality of regular quadrangular pyramids or spherical bodies on the excitation light incident surface of the phosphor layer. Even if the irradiating structure is irradiated at the same angle, the refraction direction changes depending on the irradiation position, and the excitation light is diffused in various directions in the phosphor layer. Thereby, since the excitation light spreads over a wide range in the phosphor layer, the excitation light irradiated to the phosphor increases, and it is said that the utilization efficiency of the excitation light can be increased. However, in the technique shown in Patent Document 2, since the concavo-convex structure is formed on the surface of the phosphor layer, the light scattered in the particles included in the phosphor layer immediately after entering the concavo-convex structure is from the incident point. There is a problem that the Lambertian light emission occurs, the effect of providing the uneven structure is small, and the light of the optical system cannot be effectively used.

Specifically, the fluorescent light emitted from the back side of the phosphor upon receiving the excitation light entering from the concavo-convex structure is emitted in all directions, but the excitation light incident surface has various angles. The luminous flux once reflected on the incident surface and irradiated on the reflecting surface of the fluorescent plate is also more likely to be irradiated on the excitation light incident surface at a different angle when it is irradiated on the excitation light incident surface next time. It is supposed to be used effectively. However, in other words, there is a problem in that the light emitted from the excitation light incident surface is directed in a random direction, and the emission area of the phosphor is widened with the light distribution characteristic being Lambertian, resulting in deterioration of the etendue.

The present invention has been made in view of such problems, and an object thereof is to provide a wavelength conversion member capable of improving the light distribution characteristics of a light to form a high-quality image and an image forming apparatus using the wavelength conversion member. To do.

In order to achieve at least one of the objects described above, the wavelength conversion member reflecting one aspect of the present invention is:
A wavelength conversion member in which a reflection portion, a phosphor layer, and a light deflection portion are arranged in this order in order from at least a portion of the substrate,
The light deflection unit has a plurality of optical elements having a light collecting action, and the plurality of optical elements are arranged side by side,
The light having the first wavelength incident on the optical element of the light deflector is divided by the plurality of optical elements and incident on the phosphor layer, and the first wavelength differs from the first wavelength by the phosphor layer. 2 is converted into light having a wavelength of 2, and the light having the second wavelength is reflected from the phosphor layer directly or after being reflected by the reflecting portion and then refracted by the light deflecting portion. The light is emitted so as to narrow in the line direction.

In order to achieve at least one of the above objects, an image forming apparatus reflecting one aspect of the present invention includes a light source that emits light of a first wavelength and at least one lens having positive power. A condensing optical system including a mirror; the wavelength conversion member that receives the light of the first wavelength via the optical system; a light modulation element that forms an image; and An illumination unit that guides light, and a projection optical system that projects image light from the light modulation element.

According to the present invention, it is possible to provide a wavelength conversion member that can improve the light distribution characteristics of an image to form a high-quality image, and an image forming apparatus using the wavelength conversion member.

1 is a schematic configuration diagram of an image projection apparatus 100 as an image forming apparatus according to an embodiment. 3 is a perspective view of a phosphor wheel 106. FIG. 2 is a schematic cross-sectional view of a phosphor wheel 106. FIG. It is the figure which looked at the optical deflection | deviation part 106e from the side. It is the figure which looked at the optical deflection | deviation part 106e from the incident side. It is the figure which looked at the optical deflection | deviation part 106e concerning a modification from the incident side. It is the figure which simulated the relationship between energy amount and angle (theta). It is a perspective view of 1st Example. It is a perspective view of 2nd Example. It is a figure which shows the light distribution characteristic in an emitted light when the output surface normal line of a fluorescent substance layer is 0 degree. FIG. 10 is a simulation diagram showing an example of an optical path of an incident light beam and an outgoing light beam in a cross-sectional view in which one of the optical elements of the second embodiment is cut along the axis of a conical surface. It is a simulation figure showing an example of an optical path of an incident light beam and an outgoing light beam in a sectional view which cut one optical element of a modification by a plane containing an object axis. It is sectional drawing which changes and shows the condensing position of the incident light to a fluorescent substance layer. It is a figure which shows the light distribution characteristic in the emitted light when the output surface normal line of a fluorescent substance layer is set to 0 degree | times in Example 2A-2C. It is a figure which shows the result of having examined comparatively by changing the pitch of an optical element about Example 2A. It is a figure which shows the result of having examined comparatively by changing the pitch of an optical element about Example 2A.

Hereinafter, the present embodiment will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of an image projection apparatus 100 as an image forming apparatus according to the present embodiment. Here, a configuration example of an image projection apparatus using a reflective LCD light modulation element (LCOS: Liquid crystal on silicon) as a light modulation element is shown, but the present invention is not limited to this, and a mirror array (DMD: Digital Mirror Device) is shown. Alternatively, a light modulation element using transmissive liquid crystal may be employed. A plurality of light modulation elements may be used in combination.

The image projection apparatus 100 includes an illumination unit IL from the light source 101 to the front of the LCD light modulation element 113, and an optical engine unit OE from the LCD light modulation element 113 to the projection lens 114. The optical engine unit OE has a function of optically processing the light emitted from the illumination unit IL to generate image light and enlarging and projecting the image light on an external object plane. The object plane is a wall, a screen, a whiteboard, a three-dimensional object, or the like. The optical engine unit OE includes an LCD light modulation element 113, a polarization beam splitter 112 serving as a branching element for illumination light and projection light, and a projection lens 114 for enlarging and projecting an image generated by the LCD light modulation element 113. . The polarization beam splitter 112 is also used in the illumination unit IL described later.

The configuration of the optical engine unit OE may be any configuration that includes the above-described three elements as a minimum configuration and that includes a branching element in the optical path between the LCD light modulation element 113 and the projection lens 114. If necessary, other optical elements may be added on the optical path. Examples of such an optical element include a wave plate that changes the polarization state, a polarizing filter, and a filter that corrects the color.

The LCD light modulation element 113 changes the alignment of the liquid crystal molecules and changes the polarization state of the incident light in response to the signal decomposed into the R component, G component, and B component corresponding to the image from the control unit CONT. Is combined with the polarizing film of the polarizing beam splitter to generate a modulated image.

At that time, the LCD light modulation element 113 can generate an image by a so-called color field sequential method in which the R component, the G component, and the B component are respectively divided in time, and can project a full-color image. At this time, the arrangement (field) of the liquid crystal cells changed to form the R component, G component, and B component images of the LCD light modulation element 113, and R (red light) and G (green light) of the illumination unit IL. , B (blue light) emission timing is synchronized.

On the other hand, the illumination unit IL includes a first light source 101, a beam reduction optical system 102 including a positive lens and a negative lens, a bandpass polarization filter 103, a quarter wavelength plate 104, and at least one positive lens (or A condensing lens 105 which is a condensing optical system including a mirror), a phosphor wheel 106 which is a wavelength conversion member, a motor 107 as a rotation driving unit, a first relay optical system 108, a light pipe 109, The second relay optical system 110 and the polarization beam splitter 112 are included. The first light source 101 is driven to emit light in synchronization with the rotation of the motor 107 by the laser driver DR. The band-pass polarization filter 103 is inclined at an angle of 45 degrees with respect to the optical axis, transmits P-polarized light of ± 20 nm with respect to the first wavelength of 450 nm, and has S-polarized light and a long wavelength of 500 nm or more. It has the characteristic of reflecting the light. At this time, the condensing lens 105 only needs to be set so as to be focused on the phosphor wheel 106 with a light beam diameter of a predetermined size. good.

FIG. 2 is a perspective view of the phosphor wheel 106, and FIG. 3 is a schematic cross-sectional view of the phosphor wheel 106. In FIG. 2, the phosphor wheel 106 includes a first light conversion unit 106 b in the form of a band along the circumferential direction in the vicinity of the outer periphery of the upper surface of the substrate 106 a that is a transparent disk-shaped glass, and subsequently the second light. The conversion unit 106j is formed. However, the

light conversion portions

106b and 106j are formed only for 2/3 of the substrate 106a, and the rest is obtained by forming the reflection portion 106c on the substrate 106a. That is, the 1st light conversion part 106b is formed in 1/3 circumference of the board | substrate 106a, the 2nd light conversion part 106j is formed in another 1/3 circumference, and another 1/3 circumference is reflection of the board | substrate 106a. This is a non-conversion part 106k in which only the part 106c is formed. In the center of the substrate 106a, a hole 106p for connecting to the rotating shaft of the motor 107 is formed. The substrate 106a is not necessarily made of glass, and may be a material with low absorption or a material with good heat conduction. For example, a metal material such as copper or aluminum may be used as the material with good heat conduction.

In FIG. 3, the

light conversion units

106b and 106j have the same configuration except for the phosphor layer, and a reflection layer 106c, a phosphor layer 106d, and a light deflection unit 106e as a reflection unit are stacked from the substrate 106a side. Is formed. The reflective layer 106c is formed by evaporating silver or the like on the substrate 106a. As the phosphor layer 106d of the first light conversion unit 106b, cerium activated yttrium aluminum garnet (YAG: Ce) (a typical chemical structure of the crystal matrix of this phosphor is Y ₃ (Al, Ga) ₅ O ₁₂ ), Ce or cerium activated lutetium aluminum garnet (LuAG: Ce), or β sialon phosphor can be used, but when the light of the first wavelength is incident, as the light of the second wavelength Any phosphor capable of emitting fluorescence having a peak wavelength from 500 nm to 560 nm may be used. On the other hand, a Sr sialon phosphor (Sr ₂ Si ₇ Al ₃ ON ₁₃ : Eu) or the like can be used as the phosphor layer 106d of the second light conversion unit 106j. In some cases, any phosphor may be used as long as it emits fluorescent light having a peak wavelength from 600 nm to 650 nm as the second wavelength light. In the present embodiment, the thickness of the phosphor layer 106d is 45 μm. However, since the conjugate relationship between the green light and the red light is shifted, the thickness of the phosphor layer 106j is preferably different from the thickness of the phosphor layer 106d. . The phosphor layers 106d and 106j containing the inorganic phosphor include phosphor particles having a median diameter d50 of about 8 μm to 20 μm (here 10 μm) and a binder material for fixing the phosphor particles.

4 is a view of the light deflection unit 106e as viewed from the side, and FIG. 5 is a view of the light deflection unit 106e as viewed from the incident side. As shown in the figure, the light deflection unit 106e used in common by the

light conversion units

106b and 106j is an aggregate of a plurality of minute optical elements 106h having the same shape. More specifically, as shown in FIG. 4, each optical element 106h is composed of a base portion 106f having a base thickness in contact with the phosphor layer 106d and a conical surface 106g bonded thereon and in contact with air. Become. However, the optical element 106h is not limited to a conical surface as long as it has a condensing function, and may have an aspherical surface or a spherical surface that becomes a quadrangular pyramid or a convex lens.

The optical elements 106h are arranged in a matrix. As shown in FIG. 6 (a), “matrix shape” refers to a lattice shape in which the sides of one base 106h are abutted against the sides of three adjacent bases 106h as shown in FIG. It also includes a shape in which the side of one base portion 106h is arranged with only a side of one adjacent base portion 106h but without a gap. For example, the bottom surface of the base portion 106h can be hexagonal and can be arranged in a hexagonal close-packed, so-called honeycomb shape without gaps. The efficiency can be further improved. As shown in FIG. 6B, the gaps CL may be formed between the adjacent conical surfaces 106g by cutting the four corners of the bottom surface of the conical surface 106g with an arc. The base 106f is exposed from the gap CL.

Referring to FIG. 3, the angle α of the tip in the cross section passing through the axis of the conical surface 106g is 90 degrees (rise angle is 45 degrees). The height H1 of the conical surface 106g is 100 μm when the material has a refractive index of 1.59. The height H2 of the transparent base portion 106f that supports the conical surface 106g is 125 μm when the material has a refractive index of 1.67, and thus the overall height of the light deflection portion 106e is 225 μm. The pitch p of the conical surface 106g is 150 μm.

Adjacent bases 106f are joined together to form an integral plate. The tip of the conical surface 106g is preferably sharp, but it may be a curved surface or a flat surface (shown by a dotted line in FIG. 3) because it is relatively difficult to form a sharp tip. However, the area of the curved surface or plane is 1/25, preferably 1/50 or less of the area of the base 106f. In this case, it is assumed that the conical surface also includes a shape whose tip is a flat surface or a curved surface.

The light deflection unit 106e is formed by transfer of a mold from a resin or glass material (inorganic material) having a glass transition point (Tg) of 150 ° C. or higher, and particularly in the case of a resin, the heat resistance is 100 ° C. or higher and near 450 nm. A material with low absorption is preferable, and a COP material such as “ZEONEX” manufactured by Nippon Zeon Co., Ltd. can be used as the thermoplastic resin. Further, an acrylic photo-curing resin or a thermosetting resin may be used as long as the conditions are satisfied.

When light of the first wavelength is incident on the

optical element

106h, 30% or more of the light is divided by the fine optical element 106h arranged two-dimensionally and collected on the phosphor layer 106d. It has become so.

The first light source 101 includes a solid-state light emitting element 101a that emits light having a first wavelength and a collimating lens array 101b. The solid-state light emitting device 101a uses a blue semiconductor laser array that can emit a plurality of blue lights having a wavelength of 450 nm simultaneously in order to obtain a predetermined output by multiplexing. From the solid-state light emitting device 101a, a plurality of linearly polarized blue lights having the same polarization state are emitted. The first wavelength may be any wavelength that is shorter than the wavelength of the fluorescent light emitted from the phosphor layer (second wavelength) and can be recognized as blue, but is preferably 480 nm or less. .

The operation of this embodiment will be described. Here, the phosphor wheel 106 rotates in synchronization with the field of the LCD light modulation element 113, that is, each color field and segment (the first light conversion unit 106b which is a green light emitting region of the phosphor wheel 106, the red light emitting). The second light conversion unit 106j that is a region and the non-conversion unit 106k that is a blue reflection region are controlled to synchronize. Specifically, blue light is incident on the light modulation element 113 in the blue color field of the LCD light modulation element 113, green light is incident on the edge color field, and red light is incident on the red color field. It has become.

First, blue light of linearly polarized light (P-polarized light with respect to the bandpass polarization filter 103) emitted from the solid-state light emitting element 101a of the first light source 101 passes through the collimator lens array 101b to become a plurality of parallel light beams. The collimated light beam is narrowed down by the beam reduction optical system 102, passes through the band-pass polarizing filter 103, enters the quarter-wave plate 104, is converted into a circularly polarized state, and is collected by the condenser lens 105. The light is collected and condensed as spot light on the surface side of the substrate 106a of the phosphor wheel 106 (the side where the

light conversion units

106b and 106j are formed). The phosphor wheel 106 connected to the rotation shaft of the motor 107 is driven to rotate at a predetermined speed.

The spot light is incident on one of the first light conversion unit 106b, the second light conversion unit 106j, and the non-conversion unit 106k according to the rotational position of the phosphor wheel 106. Most of the spot light incident on the first light conversion unit 106b is divided by the light deflecting unit 106e and condensed on the phosphor layer 106d, and green phosphor is generated by exciting the phosphor. This fluorescence becomes scattered light (Lambertian light distribution). Since the phosphor is located on the light condensing surface of the light deflection unit 106e, the fluorescence excited by the phosphor is on the phosphor layer 106d side of the light deflection unit 106e. The light is refracted so as to be condensed at the flat portion and the surface 106g (toward the side closer to the normal line of the substrate), and the light distribution of fluorescence is narrowed in the normal direction of the substrate. As a result, the light beam is emitted at an angle close to the incident angle of the light beam incident on the light deflection unit 106e. Further, the fluorescence toward the back side of the phosphor layer 106d is reflected by the reflecting portion 106c and then passes through the phosphor layer 106d and is emitted from the light deflecting portion 106e. However, since the thickness of the phosphor layer 106d is relatively thin. Even in the majority of the reflected light, the light converging (deflecting) action of the light deflecting unit 106e is maintained. As a result, the return light from the phosphor wheel 106 approaches the parallel light flux when passing through the condenser lens 105, and it is possible to minimize the etendue deterioration.

Here, the operation of the condenser lens 105 and the operation of the light deflection unit 106e will be described. The light having the first wavelength incident on the condensing lens 105 is collected by the condensing lens 105 and is incident on the light deflecting unit 106e as spot light with a small diameter of about φ1 mm to φ3 mm, for example. However, if the spot light collected by the condenser lens 105 is directly incident on the phosphor layer 106d without passing through the light deflecting unit 106e, the following two problems may occur.
(1) When spot light is condensed at one point by the condensing lens 105, the energy density at the condensing position becomes too high, and the phosphor layer 106d may be deteriorated at an early stage.
(2) Since the phosphor layer 106d inherently has a scattering action, when the condensing lens 105 is at a distant position, fluorescent light emitted while being scattered from the phosphor layer 106d is not taken into the condensing lens 105, Loss of light utilization efficiency occurs.

As a measure for solving these two problems, for example, it is theoretically possible to dispose the condensing position and provide a condensing lens 105 having a large NA, but this is not preferable because the condensing lens is increased in size. This is because the NA of the condensing lens 105 required when the light of the first wavelength is laser light needs about NA 0.4 to condense the light of the first wavelength, This is because NA of 0.95 or more is required to collect the light of the second wavelength, that is, a condensing lens having a diameter of 2.5 times is required. Therefore, in the present embodiment, the spot light focused to a small diameter by the condensing lens 105 is divided and dispersed by the optical element 106h of the light deflection unit 106e, so that each light quantity is reduced and a relatively thin phosphor. Since the light can be condensed on the layer 106d, deterioration of the phosphor layer 106d can be suppressed. The fluorescence generated from the phosphor layer 106d becomes the return light of the Lambertian light distribution, but is refracted and collected by the flat surface and the surface 106g of the light deflector 106e, and is incident on the light deflector 106e. Since the light is emitted at an angle close to an angle, a parallel light beam can be emitted using the condenser lens 105 having an NA that is twice or less that of the incident light beam.

Similarly, most of the spot light incident on the second light conversion unit 106j is divided by the light deflecting unit 106e, and the divided light is condensed on the phosphor layer 106d, and the phosphor is excited to red. Fluorescence occurs. In addition, the small difference between the NA of the forward light flux that has passed through the condenser lens 105 and the NA of the return path before the return light from the phosphor wheel 106 enters the condenser lens 105 minimizes the deterioration of the etendue. This means that it can be limited to the limit. On the other hand, the spot light (blue light) incident on the non-converting portion 106k is directly reflected by the reflecting portion 106c and passes through the condenser lens 105 again to become a parallel light beam.

Of the parallel light flux that has passed through the condenser lens 105, blue light passes through the quarter-wave plate 104 and becomes S-polarized, and green light and red light are reflected by the bandpass polarization filter 103 regardless of polarization. The Illumination light in which blue light, green light, and red light sequentially reflected by the bandpass polarization filter 103 is incident on the light pipe 109 via the first relay optical system 108, and is then reflected by the second light. The light passes through the relay optical system 110, is reflected by the polarization beam splitter 112, and enters the LCD light modulation element 113. By passing through the light pipe 109 and the second relay optical system 110, the illumination light is guided to the LCD light modulation element 113 in a state in which the luminance unevenness due to the light source and the phosphor layer is alleviated. Yes. Although not shown, a so-called polarization conversion element that uniformly aligns the polarization state is inserted in the optical path from the bandpass polarization filter 103 to the polarization beam splitter 112 in order to reduce light loss due to polarization. May be.

Furthermore, the LCD light modulation element 113 becomes a blue color field when blue light is incident, a green color field when green light is incident, and a red color field when red light is incident. Divided images can be formed and projected through the projection lens 114 of the optical engine unit OE. A person who observes each projected image can visually recognize a full-color image obtained by adding the components by the afterimage effect of the eyes.

In the above embodiment, the example in which the two

light conversion units

106b and 106j are formed on the phosphor wheel 106 has been described. For example, the phosphor wheel 106 includes the first light that converts blue light into green light. Alternatively, the conversion unit 106b and the non-conversion unit 106k may be provided, and instead, the red light emitted from the red semiconductor light source may be guided to the LCD light modulation element 113 using a dichroic filter or the like.

Hereinafter, the examination results performed by the present inventors will be described with reference to the simulation results of FIGS. In FIG. 7, the horizontal axis indicates the angle (θ) with respect to the emission surface normal of the phosphor layer of 0 degree, and the vertical axis indicates a predetermined solid angle in which the angle of the horizontal axis is a half apex angle. This is the density of the light beam contained in (referred to as the amount of light energy). The solid angle at that time is represented by 2π (1-cos θ) using the angle θ on the horizontal axis. Here, a comparative example without an optical deflecting unit, a first example in which a regular quadrangular pyramid is formed as an optical element of the optical deflecting unit (see FIG. 8), and a second example in which a cone is formed as an optical element of the optical deflecting unit. (See FIG. 9).

According to the simulation result of FIG. 7, in the comparative example without the light deflecting portion, the amount of light energy increases rapidly in the range where the angle θ is about 60 degrees or more. This is the emission surface method of the phosphor layer. This means that the amount of light energy decreases in the vicinity of the line direction, that is, an illumination optical system with a high NA is required, and the amount of light that is effectively used as illumination light tends to decrease. On the other hand, in the first example in which a regular quadrangular pyramid is formed as an optical element of the light deflection unit, the amount of light energy is increased in the range where the angle θ is 60 degrees or less compared to the comparative example. Furthermore, in the second embodiment in which a cone is formed as the optical element of the light deflecting unit, the amount of light energy is increased in the range where the angle θ is 65 degrees or less compared to the comparative example, and the first embodiment is compared with the first embodiment. However, the amount of energy exceeds almost the entire area, indicating that there are many light beams that can be effectively used in the illumination optical system with a lower NA.

FIG. 10 is a diagram showing the light distribution characteristics of the emitted light when the emission surface normal of the phosphor layer is 0 degree. As shown in FIG. 10, in the comparative example having no light deflecting portion, the emitted light has a Lambertian emission distribution. On the other hand, in the first embodiment, the luminance in the direction of the emission angle of 0 degree is increased about twice, and the light use efficiency at a low NA can be improved. Furthermore, in the second embodiment in which a cone is formed as an optical element of the light deflector, the luminance in the direction of the emission angle of 0 degrees is more than doubled as compared with the first embodiment, and the light utilization efficiency is further improved. Can do.

FIG. 11 is a simulation view showing an example of the optical paths of the incident light beam and the outgoing light beam in a cross-sectional view of one of the optical elements of the second embodiment cut along the axis of the conical surface. The example which injected the parallel light beam is shown. Part of the light beam incident on the optical element is refracted by the conical surface 106g, exits from the base 106f, and then is condensed on a phosphor layer (not shown) on the inner side and scattered from the condensing point. It can be seen that the light enters the base portion 106f and is refracted and emitted from the conical surface 106g. The light incident on the conical surface 106g is refracted or reflected according to the incident angle. This reflected light returns to the phosphor layer again, is reflected by the reflection part on the back side, and is emitted from the phosphor layer again. By repeating the above, almost all light is emitted.

The optical element may be replaced with a conical surface to be an aspherical surface 106g 'targeted for the axis (third embodiment). FIG. 12 is a simulation diagram showing an example of an optical path of an incident light beam and an outgoing light beam in a cross-sectional view in which one of optical elements as the third embodiment is cut along a plane including a symmetry axis. It turns out that 3rd Example has a high condensing effect compared with 2nd Example. Therefore, it is assumed that a higher effect can be obtained.

Furthermore, the condensing position of incident light on the phosphor layer will be considered. FIG. 13A shows an embodiment 2A having an optical element of a light deflecting portion in which a cone is formed and having a condensing position as the center of the phosphor layer. FIG. 13B shows a second B embodiment in which a cone is similarly formed as an optical element of the light deflector, but the light condensing position is 0.1 mm before the phosphor layer 106d. FIG. 13C similarly shows a second C embodiment in which a cone is formed as an optical element of the light deflector, but the condensing position is 0.1 mm behind the phosphor layer 106d.

FIG. 14 is a diagram showing the light distribution characteristics of the emitted light when the emission surface normal of the phosphor layer is set to 0 degree in Examples 2A to 2C. As shown in FIG. 14, in the comparative example having no light deflection unit, it can be said that the emitted light becomes a light distribution of the Lambertian and the light use efficiency is low. On the other hand, in all of the second A to 2C embodiments, the amount of light in the direction of the emission angle of 0 degrees is increased, and the light use efficiency can be improved. However, the amount of light in the direction of the emission angle of 0 degree is the largest in the 2A example, that is, the light distribution characteristic of the emitted light is the best when the light is condensed on the phosphor layer 106d. However, since the condensing state varies depending on the position (distance from the optical axis, etc.) of the optical element 106h in the light deflecting unit 106e, the condensing position of all the optical elements 106h is within the phosphor layer 106d. Have difficulty. Therefore, if 30% or more of the light having the first wavelength incident on the light deflecting unit 106e is condensed in the phosphor layer 106d, the light distribution characteristic of the emitted light is that shown in the second embodiment. It is possible to secure high light use efficiency. In addition, even if the light having the first wavelength incident on the light deflecting unit 106e is not condensed in the phosphor layer 106d, the second B, if the condensing position is not separated from the phosphor layer 106d. Since the light distribution characteristics of the emitted light can be improved as shown in the 2C embodiment, there is an effect in increasing the light use efficiency.

Furthermore, the pitch p of the optical element will be considered. 15 and 16, in Example 2A, the pitch p (see FIG. 3) of the optical element is changed in accordance with a multiple of the average (median diameter) of the particle diameter of the phosphor layer (for example, 5 times if x5). It is a diagram showing a result of simulation compared with a comparative example without a light deflection unit. FIG. 15 shows the result of comparing the amount of energy (vertical axis) of the light emitted from the light deflecting unit with three types of angles θ = 30 degrees, 60 degrees, and 90 degrees, and FIG. In the case of θ = 90 degrees, the center luminance values (vertical axis) of the light emitted from the light deflecting unit are respectively shown in comparison. According to the examination results of FIGS. 15 and 16, an effect can be obtained to some extent even if the pitch p of the optical element is set to be not more than four times the average (median diameter) of the particle diameter of the phosphor layer. It can be seen that if the average particle diameter (median diameter) of the phosphor layer is 5 times or more, a sufficient amount of energy can be secured and illumination light with high luminance can be realized. However, if it is too large, the effect of division is reduced, so it is desirable that the average particle diameter (median diameter) of the phosphor layer be 20 times or less. Preferably, the pitch p of the optical element is 10 times or more the average (median diameter) of the particle diameter of the phosphor layer.

The present invention is not limited to the embodiments and examples described in the present specification, and includes other embodiments and examples, and includes the embodiments, examples, and technical ideas described in the present specification. To those skilled in the art. The description of the specification and the embodiments / examples are for illustrative purposes only, and the scope of the present invention is indicated by the claims to be described later.

DESCRIPTION OF SYMBOLS 100 Image projector 101 Light source 101a Solid light emitting element 101b Collimating lens array 102 Beam reduction optical system 103 Band pass polarizing filter 104 1/4 wavelength plate 105 Condensing lens 106 Phosphor wheel 106a Glass substrate 106b 1st light conversion part 106c Reflection Layer (reflection part)
106d phosphor layer 106e light deflector 106f base 106g conical surface 106g ′ aspherical surface 106h optical element 106j second light converter 106k nonconverter 106p hole 107 motor 108 first relay optical system 109 light pipe 110 second relay optical system 112 Polarizing beam splitter 113 LCD light modulation element 114 Projection lens CONT Control unit DR Laser driver IL Illumination unit OE Optical engine unit

Claims

A wavelength conversion member in which a reflection portion, a phosphor layer, and a light deflection portion are arranged in this order in order from at least a portion of the substrate,
The light deflection unit has a plurality of optical elements having a light collecting action, and the plurality of optical elements are arranged side by side,
The light having the first wavelength incident on the optical element of the light deflector is divided by the plurality of optical elements and incident on the phosphor layer, and the first wavelength differs from the first wavelength by the phosphor layer. 2 is converted into light having a wavelength of 2, and the light having the second wavelength is reflected from the phosphor layer directly or after being reflected by the reflecting portion and then refracted by the light deflecting portion. A wavelength conversion member configured to emit light so as to narrow in a line direction.
The wavelength conversion member according to claim 1, wherein a surface on which light of the first wavelength of the optical element of the light deflection unit is incident includes a spherical surface or an aspherical surface.
The wavelength conversion member according to claim 1, wherein a surface on which light of the first wavelength of the optical element of the light deflection unit is incident includes a conical surface.
The wavelength conversion member according to any one of claims 1 to 3, wherein the optical elements of the light deflector are arranged in a matrix as viewed from the light emission side of the second wavelength.
The wavelength conversion member according to any one of claims 1 to 4, wherein the light deflection section is made of a material having a glass transition point (Tg) of 150 ° C or higher.
The wavelength conversion member according to any one of claims 1 to 5, wherein the light deflection section is made of an inorganic material.
The wavelength conversion member according to any one of claims 1 to 6, wherein the phosphor layer is composed of a layer containing an inorganic phosphor.
The wavelength conversion member according to any one of claims 1 to 7, wherein the phosphor layer is mixed with a plurality of particles having a particle size having a median diameter d50 of 8 µm to 20 µm.
The wavelength conversion member according to claim 8, wherein the pitch of the optical elements of the light deflection unit is 5 to 20 times the average (median diameter) of the particle diameter of the phosphor layer.
The wavelength converting member according to any one of claims 1 to 9, wherein a wavelength having the highest light intensity among the second wavelengths is any of 500 nm to 560 nm.
The wavelength conversion member according to any one of claims 1 to 10, wherein the first wavelength is 480 nm or less.
The phosphor layer and the light deflection section are provided in a part of a circumferential direction of the wavelength conversion member, and the reflection section is provided over the entire circumference of the wavelength conversion member. The wavelength conversion member as described in 2.
A light source that emits light of a first wavelength, a condensing optical system that includes at least one lens or mirror having positive power, and light of the first wavelength is incident through the optical system. The wavelength conversion member according to any one of 1 to 12, a light modulation element that forms an image, an illumination unit that guides light from the wavelength conversion member to the light modulation element, and image light from the light modulation element An image forming apparatus having a projection optical system for projecting.
The image forming apparatus according to claim 13, wherein the light source is a semiconductor laser.
A rotation drive unit configured to rotate the wavelength conversion member; and the wavelength conversion member is condensed through the condensing optical system by rotating the wavelength conversion member by the rotation drive unit. The image forming apparatus according to claim 13, wherein a position where light having a wavelength of 1 is incident on the light deflection unit and a position other than the position are selectively taken.
Control for controlling the image signal to the light modulation element in synchronization with the time when the light of the first wavelength is incident on the light deflector and the time when the light is incident on the other position. The image forming apparatus according to claim 15, further comprising a portion.