JP2013105627A - Light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light source device that emits linearly-polarized light, wherein: the quantity of light emitted is increased; and a structure of the light source device is simplified.SOLUTION: A light source device 1 includes: a light source 2 having a light-emitting diode (LED) element 21; a reflecting member 4 having a reflecting surface 4a that surrounds the light source 2; and a reflective linear polarizer 5 provided on a light-emitting side of the reflecting member 4 without a retardation plate.

Description

  The present invention relates to a light source device, and more particularly to a light source device that emits linearly polarized light.

  Conventionally, linearly polarized light has been used in liquid crystal projectors using transmissive and reflective liquid crystal panels. As a method for obtaining linearly polarized light, for example, a method is known in which non-polarized light emitted from a light source is transmitted through a linear polarizer. However, according to such a method, only about 1/2 of the amount of light emitted from the light source can be used, and the light use efficiency is not necessarily excellent.

  A method of converting non-polarized light into linearly polarized light by combining a prism and a half-wave plate is also known. Although the conversion efficiency from non-polarized light to linearly polarized light is as high as about 80%, there are problems that the member is expensive and the light source is enlarged. Further, for the purpose of making the illuminance uniform, a combination with a fly-eye lens has been proposed, but there are problems of higher cost and a larger light source.

  As a light source device with improved light utilization efficiency, a reflector is provided so as to surround the light source, and only a linearly polarized light component in a predetermined direction is transmitted through the opening of the reflector so that the remaining polarized light component is reflected. It is known that a polarizer is provided and birefringence means such as a retardation plate is provided on the light incident side of the reflective linear polarizer. According to such a light source device, the polarized light component that does not pass through the linear polarizer is reflected and passed back and forth through the birefringence means, thereby changing the polarization state to include the linearly polarized light component in a predetermined direction. It can be taken out efficiently (for example, see Patent Document 1).

JP 2007-114375 A

  However, the light source device that emits linearly polarized light is required to increase the amount of emitted light and to simplify the structure. Furthermore, the above-mentioned light source device does not mention uniformity of illuminance.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a light source device that emits linearly polarized light and that can achieve an increase in the amount of emitted light and simplification of the structure. It is another object of the present invention to provide a light source device that can achieve uniform illumination.

  The light source device of the present invention includes a light source having a light emitting diode element, a reflecting member having a reflecting surface surrounding the light source, and reflective linearly polarized light provided on the light emitting side of the reflecting member without a retardation plate. It has a child. Further, in order to make the illuminance uniform, a light amount adjusting film that absorbs or reflects a part of incident or emitted light is provided on the central portion on either main surface side of the linear polarizer.

  According to the light source device of the present invention, a light source having at least a light emitting diode element is used as a light source, a reflection member having a reflection surface surrounding the light source is provided, and a phase difference plate is not provided on the light emission side of the reflection member. By providing a reflective type linear polarizer, it is possible to increase the amount of emitted light and simplify the structure. Thereby, it can contribute to the cost reduction and size reduction of a light source.

  Furthermore, by providing a light amount adjusting film that absorbs or reflects a part of incident or emitted light on the central portion on either main surface side of the linear polarizer, uniform illumination can be achieved. Thereby, it can contribute to the further cost reduction and size reduction of a light source.

Sectional drawing which shows 1st Embodiment of a light source device. The partial top view which shows 1st Embodiment of a light source device. Sectional drawing which shows the modification of the light source device of 1st Embodiment. Sectional drawing which shows typically the light ray locus | trajectory in the light source device of 1st Embodiment. The top view which shows typically the light ray locus | trajectory in the light source device of 1st Embodiment. Sectional drawing which shows 2nd Embodiment of a light source device. Sectional drawing which shows the modification of the light source device of 2nd Embodiment. The figure which shows the result of the illumination intensity position dependence of the light source device of Example 1. The figure which shows the result of the luminous intensity angle dependence of the light source device of Example 1. The figure which shows the result of the illumination intensity position dependence of the light source device of Example 2. The figure which shows the result of the luminous intensity angle dependence of the light source device of Example 2. The figure which shows the result of the illumination intensity position dependency of the light source device of Example 3. The figure which shows the result of the luminous intensity angle dependence of the light source device of Example 3. Sectional drawing which shows the inner surface shape of a reflection member typically.

Hereinafter, the light source device of the present invention will be described.
FIG. 1 is a cross-sectional view showing a first embodiment of a light source device. FIG. 2 is a partial plan view of the light source device shown in FIG.

  The light source device 1 includes, for example, a substrate 3 on which a light source 2 is provided, a reflecting member 4 provided so as to surround the light source 2 on a main surface side on which the light source 2 of the substrate 3 is provided, and light emission of the reflecting member 4. And a reflective linear polarizer 5 provided on the side.

  The substrate 3 is, for example, a substantially plate shape having a recess at the center, and the light source 2 is provided in the recess. Here, the abbreviation refers to a state that looks like that when observed with the naked eye or a state close to such a concept. The light source 2 includes, for example, a light emitting diode element 21 disposed on the bottom surface of the recess and a phosphor layer 22 provided so as to cover the light emitting diode element 21 and emits white light. Hereinafter, the light emitting diode element 21 is referred to as an LED element 21. On the light emitting side of the light source 2, for example, a substantially hemispherical potting portion 6 made of a translucent material for increasing the amount of light taken out is provided so as to cover the entire light source 2.

  In addition, the light source 2 is not necessarily limited to what emits the white light which consists of the LED element 21 and the fluorescent substance layer 22, and may emit monochromatic light which consists only of the light emitting diode element 21. FIG. Moreover, the board | substrate 3 does not necessarily need to have a recessed part in the center part, and the light source 2 may be provided on the surface of the flat board | substrate 3 which does not have a recessed part. Furthermore, the potting unit 6 is not necessarily an essential configuration, and a configuration in which the potting unit 6 is not provided as shown in a modified example in FIG.

  The reflecting member 4 is a cylindrical body, for example, and is provided on the substrate 3 so as to surround the light source 2. When the reflecting member 4 is a cylindrical body, the inner surface is the reflecting surface 4a. The reflecting surface 4a is a parabolic surface that is a curved surface obtained by rotating a parabola with the optical axis passing through the light source 2 as a symmetric axis around the symmetric axis, and focuses on the position of the light source 2. . In other words, the reflecting member 4 is a parabolic mirror whose focal point is the position of the light source 2, for example. In that case, the light emitted from the light source 2 is reflected by the reflecting surface 4a as substantially parallel light with respect to the optical axis.

  The reflecting member 4 has an opening on the light incident side that is the light source 2 side, and an opening on the light emitting side that is the opposite side. A linear polarizer 5 is provided on the light emitting side of the reflecting member 4 so as to cover the entire opening on the light emitting side. The linear polarizer 5 is provided on the light exit side of the reflecting member 4 without using a retardation plate used in a conventional light source device, for example, a quarter wavelength plate.

  According to such a light source device 1, the light source 2 has at least the LED element 21, and this LED element 21 is a surface light source that emits surface light although it is small unlike a point light source. Therefore, the light emitted from the surface light source becomes light emitted at an angle slightly deviated from the optical axis by the reflecting surface 4a. The emitted light is transmitted by the linear polarizer 5 while light having a predetermined linear polarization component is transmitted and light having an orthogonal polarization component is reflected. However, deviation from regular reflection occurs, and deviation occurs in the reflection position and polarization direction. That is, for example, as shown in FIG. 4, the non-polarized light emitted from the light source 2 is reflected by the reflecting surface 4a of the reflecting member 4 and reaches the linear polarizer 5, and the transmitted light component which is a predetermined linearly polarized component. Passes through the linear polarizer 5 and the other polarization components are reflected. The reflected light does not return to the focal position of the reflecting surface 4a, but returns to a position slightly deviated from the focal position. The reflected light that has returned to a position slightly deviated from the focal position is re-emitted as shown in FIG. 5, for example, and is repeatedly reflected in all directions by the reflecting surface 4a.

  Polarization conversion is gradually performed by such re-emission and repeated reflection, and a transmitted light component which is a predetermined linearly polarized light component is included. This transmitted light component is gradually transmitted through the linear polarizer 5 in the process of re-emission and repeated reflection. As a result, according to the light source device 1, it is possible to efficiently emit linearly polarized light having a uniform polarization direction. Moreover, according to the light source device 1, since the polarization conversion is performed by re-emission or repetitive reflection, a retardation plate provided on the light incident side of the linear polarizer separately from the linear polarizer in the conventional light source device, for example, 1 / 4 wavelength plate can be omitted. By omitting the retardation plate, the amount of emitted light can be increased and the structure can be simplified. Further, the cost can be reduced.

  The constituent material of the substrate 3 in the light source device 1 is not particularly limited, and for example, a metal material such as aluminum, a ceramic material such as silicon nitride or aluminum nitride, a glass ceramic material, or a resin material can be used. Here, the glass ceramic material is a fired product of a glass ceramic composition containing glass powder and a ceramic filler. Hereinafter, the glass ceramic material will be described.

Glass powder in the glass ceramic composition, for example, by mol% based on oxides, the _{SiO 2 57~65%, B 2 O} 3 and 13 to 18%, the CaO 9 to 23%, the _Al 2 _{O 3} 3 to 8%, at least one selected from K ₂ O and Na ₂ O is contained in a total amount of 0.5 to 6%.
Hereinafter, the reason why the components of the glass powder are limited will be described with mol% simply being%.

SiO ₂ becomes a glass network former. By setting the content of SiO ₂ to 57% or more, the glass can be stabilized and chemical durability can be ensured. On the other hand, by setting the content of SiO ₂ to 65% or less, an excessive increase in the glass transition point represented by the glass melting temperature or Tg can be suppressed. The content of SiO ₂ is preferably 58% or more, more preferably 59% or more, and particularly preferably 60% or more. Further, the content of SiO ₂ is preferably 64% or less, more preferably 63% or less. In the present specification, the glass transition point is hereinafter referred to as Tg.

B ₂ O ₃ is a glass network former. By setting the content of B ₂ O ₃ to 13% or more, an excessive increase in the glass melting temperature or Tg can be suppressed. On the other hand, by setting the content of B ₂ O ₃ to 18% or less, the glass can be stabilized and chemical durability can be ensured. The content of B ₂ O ₃ is preferably 14% or more, more preferably 15% or more. Further, the content of B ₂ O ₃ is preferably 17% or less, more preferably 16% or less.

Al ₂ O ₃ improves the stability, chemical durability, and strength of the glass. By setting the content of Al ₂ O ₃ to 3% or more, the glass can be stabilized. On the other hand, by setting the content of Al ₂ O ₃ to 8% or less, an excessive increase in the glass melting temperature and Tg can be suppressed. The content of Al ₂ O ₃ is preferably 4% or more, more preferably 5% or more. Further, the content of Al ₂ O ₃ is preferably 7% or less, more preferably 6% or less.

  CaO increases glass stability and crystal precipitation, and lowers the glass melting temperature and Tg. By making the content of CaO 9% or more, an excessive increase in the glass melting temperature can be suppressed. On the other hand, glass can be stabilized by content of CaO being 23% or less. The content of CaO is preferably 12% or more, more preferably 13% or more, and particularly preferably 14% or more. Further, the content of CaO is preferably 22% or less, more preferably 21% or less, and particularly preferably 20% or less.

K ₂ O and Na ₂ O lower Tg. By making the total content of K ₂ O and Na ₂ O 0.5% or more, it is possible to suppress an excessive increase in the glass melting temperature or Tg. On the other hand, when the total content of K ₂ O and Na ₂ O is 6% or less, chemical durability, particularly acid resistance can be secured, and electrical insulation can be secured. The total content of K ₂ O and Na ₂ O is preferably 0.8% or more and 5% or less.

  The ceramic filler improves the reflectance of the glass ceramic. Examples of the ceramic filler include ceramic fillers conventionally used in the production of glass ceramics, and include alumina filler, zirconia filler, stabilized zirconia filler, titania filler, and a mixture of two or more selected from these.

  For example, the glass powder and the ceramic filler preferably contain 25 to 55% of glass powder and 45 to 75% of ceramic filler in terms of mass percentage. If the content of the glass powder is less than 25%, it may be difficult to obtain a dense fired product by firing, preferably 35% or more. Moreover, there exists a possibility that intensity | strength may be insufficient when content of the powder of glass exceeds 55%, Preferably it is 50% or less, More preferably, it is 45% or less.

  The ceramic filler is a component that increases the strength of the substrate. The content is more preferably 50% or more, particularly preferably 55% or more. If the content of the ceramic filler is more than 75%, it may be difficult to obtain a dense fired product by firing, or the smoothness of the substrate surface may be impaired, and it is preferably 65% or less.

  The glass powder and the ceramic filler can contain an inorganic powder, such as a heat-resistant pigment, as other components within a range not impairing the object of the present invention. In that case, the content of the other components is typically 5% or less in total.

  As the ceramic filler, a flat (that is, flake-shaped) ceramic filler having an average aspect ratio of 25 or more may be used. The upper limit of the average aspect ratio of the flat ceramic filler is preferably 200 or less, and more preferably 100 or less. If the average aspect ratio is too large, the thickness of the flat filler becomes thin, and therefore, there is a risk of being crushed by the ceramic balls in the ball mill mixing operation at the time of slurry preparation. On the other hand, if the aspect ratio is too large, the ratio of the flat surface where the surface area is increased and the interaction between particles is likely to increase increases, making it difficult to uniformly disperse the filler during slurry preparation. As a result, the composition of the green sheet may be offset, it may be difficult to make the film thickness uniform, or the subsequent manufacturing process of the glass ceramic composition may be hindered.

  The aspect ratio means a value obtained by dividing the long diameter of the flat filler particle (the flat plane is the xy plane, for example, the diameter in the x-axis direction) by the thickness (the length in the z-axis direction perpendicular to the flat plane). To do. It is also possible to use a mixture of multiple types of flat ceramic fillers, in which case the value obtained from the sum of the values obtained by multiplying the aspect ratio of each ceramic filler and its presence ratio, Average aspect ratio. By including the flat ceramic filler in a state of being oriented in parallel to the surface direction of the substrate, the reflectance of light in the visible light region of the substrate 3 can be increased.

  In the light source device 1, since the reflected light from the linear polarizer 5 is repeatedly reflected, the substrate 3 preferably has high light reflectivity, for example, is preferably made of a metal material such as aluminum having high light reflectivity. . Further, when a resin material, a ceramic material, or a glass ceramic material is provided, it is preferable to provide a highly reflective film made of a highly reflective metal material such as silver, aluminum, chromium, magnesium, platinum on the surface thereof, In particular, it is preferable to provide a highly reflective film made of silver or aluminum. Examples of the method for forming the highly reflective film include vapor deposition methods such as PVD or CVD, sputtering methods, ion plating methods, and plating methods.

  Examples of the LED element 21 include an LED element that emits blue light. The size of the LED element 21 is not necessarily limited, but a square shape or a rectangular shape having a side length of 0.5 to 10 mm is preferable from the standard LED element size. Moreover, although it does not necessarily limit about thickness, 0.05-0.5 mm is preferable.

  Examples of the phosphor layer 22 include a material in which a yellow phosphor that is excited by blue light and emits yellow light is dispersed in a resin material such as silicone resin. In addition, in order to improve color reproducibility, red phosphors and green phosphors are dispersed. Although the magnitude | size of the fluorescent substance layer 22 is not necessarily limited, The square shape whose one side length is 0.5-15 mm, a rectangular shape, or circular shape is preferable.

  Examples of the constituent material of the reflecting member 4 include metal materials such as aluminum, ceramic materials such as silicon nitride and aluminum nitride, glass ceramic materials, and resin materials. As a glass ceramic material, since the glass ceramic material which comprises the board | substrate 3 is a highly reflective glass ceramic member, it can be used as the reflection member 4. FIG.

  The reflecting member 4 is preferably made of a metal material such as aluminum having high light reflectivity because the reflecting member 4 repeatedly reflects the reflected light reflected by the linear polarizer 5. Further, when a resin material, a ceramic material, or a glass ceramic material is used, a highly reflective film made of a metal material having a high light reflectivity such as silver, aluminum, chromium, magnesium, or platinum is provided on the surface, particularly the reflective surface 4a. In particular, it is preferable to provide a highly reflective film made of silver or aluminum. Examples of the method for forming the highly reflective film include vapor deposition methods such as PVD or CVD, sputtering methods, ion plating methods, and plating methods. The reflective surface 4a is preferably specularly reflected, and is preferably in a mirror state.

The inner surface shape of the reflecting member 4 is as follows. From the parabolic equation (1), r ² = 4az (1)
r: radius from the central axis of the paraboloid a: focal position z: central axis (exit side is positive)
And is represented as shown in FIG. Here, when the opening shape is square or rectangular, the inner surface shape may be defined by replacing the radius r with the respective plane coordinates x and y.

Since the incident side end face position of the reflecting member 4 is substantially a focal point, the length L of the reflecting member 4 is expressed by the following equation (2).
z = a + L (2)
L: Length of the reflecting member

Furthermore, the area S ₂ of the surface area S ₁ and the exit side of the entrance side are expressed as follows.
S ₁ = π (2a) ² (3)
S ₂ = π (4az) ² = π (4a (a + L)) ² (4)

Therefore, the area ratio S ₂ / S ₁ is expressed as follows.
S ₂ / S ₁ = 4 (a + L) ² (5)

According to the radiation law, the product of the area through which light is transmitted and the solid angle is constant, so the incident / exit area and the light distribution angle are in an inversely proportional relationship. Therefore, in order to emit substantially parallel light on the emission side, the area of the emission surface needs to be set larger than that of the incident surface.
When the commercially available LED light has a Lambert light distribution with a full angle of 120 degrees and the projection angle of the projector is about 36 degrees or less, the range of the area ratio S ₂ / S ₁ is set to the following equation (6).
S ₂ / S ₁ ≧ 10 (6)

From equations (2) and (5), the inequality of equation (6) is converted to equation (7).
z ≧ 1.6 (7)

Here, when the relationship between the diameter or the length of one side of the LED element and the phosphor layer described above and the diameter or the length of one side 2a × 2 of the reflecting member is expressed by Equation (8).
0.5 ≦ 2a × 2 ≦ 15 (8)

Therefore, the range of the focal point a is as follows.
0.125 ≦ a ≦ 3.75 (9)

From Expression (7), the length L of the reflecting member is as follows.
L ≧ 1.475 (10)

Further, from the expressions (3), (6), (9), and (10), the areas of S ₁ and S ₂ are as follows.
π (2 × 0.125) ² ≦ S ₁ ≦ π (2 × 3.75) ² (11)
S ₂ ≧ 10 × π (2 × 0.125) ² (12)

  In consideration of mounting the light source device 1 of the present invention on a projector device, the diameter of the opening on the light emission side or the length of one side is preferably 1.4 to 100 mm due to the size restriction. Accordingly, the length of the reflecting member 4, that is, the length L from the light incident side opening to the light emitting side opening is preferably 1.475 to 163 mm from the equations (1) and (2). The shape of the opening on the light incident / exit side of the reflecting member 4 is preferably square, rectangular, or circular depending on the shape of the light source 2 and the required shape of the emitted light. For example, when used as a light source for a liquid crystal panel, the shape of the opening on the exit side is preferably rectangular, and when used as a light source such as a spotlight, the shape of the opening on the exit side is preferably circular.

  The linear polarizer 5 is not particularly limited as long as it is a reflective linear polarizer, and may be any one that transmits a linearly polarized light component in a predetermined direction and reflects the remaining polarized light component. By providing the linear polarizer 5, it is possible to reflect polarization components other than the linear polarization component in a predetermined direction, and it is possible to reuse polarization components other than the linear polarization component in the predetermined direction. As the linear polarizer 5, one using a difference in reflectance of a polarization component depending on the Brewster angle, one made of a laminate of a cholesteric liquid crystal and a quarter wave plate, one having a thin metal wire, a predetermined polarization by a dye And those utilizing the reflectance anisotropy due to refractive index anisotropy.

  For example, what has what is called a metal grid polarizer is mentioned as what has a metal fine wire. The wire grid polarizer has fine metal wires periodically arranged on a substrate. When the period (pitch) of the fine metal wires is sufficiently small with respect to the wavelength used, light having an electric field component perpendicular to the fine metal wires is transmitted without being affected by the fine metal wires. On the other hand, light having an electric field component parallel to the fine metal wire is reflected by the fine metal wire. Thereby, the linearly polarized light component in a predetermined direction can be transmitted and the remaining polarized light component can be reflected.

  As a constituent material of the fine metal wire, silver, aluminum, chromium, magnesium, and platinum are preferable, and aluminum is particularly preferable because it has high visible light reflectance and low visible light absorption. Examples of the cross-sectional shape of the fine metal wire include a square, a rectangle, a trapezoid, a circle, an ellipse, and other various shapes. Examples of the method for forming the fine metal wires include vapor deposition methods such as PVD or CVD, sputtering methods, ion plating methods, and plating methods.

  The fine metal wire is very fine in thickness and width, and the performance of the wire grid polarizer is degraded by slight scratches. Moreover, the electrical conductivity of a metal fine wire falls by rust, and the performance of a wire grid type polarizer falls. In order to suppress such damage and rust of the fine metal wires, the fine metal wires may be covered with a protective layer. Examples of the protective layer include resins, metal oxides, and glass. For example, when aluminum is used as the metal, it is oxidized in the air to form aluminum oxide on the surface. Such a metal oxide film functions as a protective layer for the fine metal wires.

  Commercially available products can also be used as the linear polarizer 5, and examples of such a linear polarizer include DBEF (manufactured by Sumitomo 3M, trade name). The DBEF is a multilayer optical film having a laminated structure using a high birefringent polymer and a combination of a high refractive index material / low refractive index material. The DBEF has a refractive index difference in a certain in-plane direction, and has no refractive index difference in a direction orthogonal thereto. With such a structure, light that vibrates in a direction with a refractive index difference can be reflected, and light that vibrates in a direction without a refractive index difference can be transmitted.

  For example, in order to make the illuminance of the light source device 1 uniform, one of the light incident on the linear polarizer 5 or the light emitted from the linear polarizer 5 is placed on the central portion on the main surface side of any one of the linear polarizers 5. A light amount adjustment film 7 that absorbs or reflects the portion can be provided. As for the light source device 1, in principle, the illuminance on the central portion of the linear polarizer 5, specifically on the central portion of the light emitting side opening of the reflecting member 4, is higher than the illuminance of other portions. Sometimes. By providing the light amount adjustment film 7 that absorbs or reflects a part of the incident or emitted light on the central portion on the main surface side of the linear polarizer 5, the illuminance of the light source device 1 can be made uniform. Examples of the light amount adjustment film 7 include an absorption film that absorbs part of light and a reflection film that reflects part of light, and any of these may be used.

  As the light amount adjusting film 7, for example, a material made of silver, aluminum, chromium, magnesium, platinum, or the like is preferable because it has a high reflectance for visible light and little absorption of visible light. Or what consists of aluminum is mentioned as a suitable thing. Examples of the method for forming the light amount adjusting film 7 include a vapor deposition method such as PVD or CVD, a sputtering method, an ion plating method, and a plating method. Silica, titania, alumina, lanthanum fluoride, magnesium fluoride, sodium aluminum hexafluoride, zirconia, tantalum pentoxide, niobium pentoxide, lanthanum oxide, yttria, zinc oxide, zinc sulfide due to low absorption and high reflectance You may comprise with the multilayer film which consists of an isoelectric material.

  The light amount adjustment film 7 is preferably provided on the light emitting side. When the light amount adjusting film 7 is provided on the light incident side, the reflected light from the linear polarizer 5 is reflected again by the light amount adjusting film 7 and is repeatedly reflected between the two to finally become the leaked emitted light of the light source device 1. Because. Further, when the light amount adjusting film 7 has absorption, the light emitting side is preferable from the viewpoint that a light amount loss occurs when it is provided on the light incident side of the linear polarizer 5 compared to the light emitting side.

  The light amount adjustment film 7 is more preferably provided on the central portion of the linear polarizer 5, specifically on the central portion of the light emitting side opening of the reflecting member 4. The shape of the light amount adjusting film 7 is preferably a similar shape to the shape of the light emitting side opening of the reflecting member 4. The size of the light amount adjusting film 7 is preferably 1/10 to 1/30 of the size of the opening on the light emitting side of the reflecting member 4, that is, the diameter or the length of one side.

Next, a second embodiment of the light source device 1 will be described.
FIG. 6 is a cross-sectional view showing a second embodiment of the light source device 1. The light source device 1 also includes a light source 2, a substrate 3, a reflecting member 4, and a linear polarizer 5. The light source device 1 according to the second embodiment is different particularly in that the entire reflection member 4 is uniformly formed of a translucent material and totally reflects light on the outer peripheral side surface. In other words, the outer peripheral side surface of the reflecting member 4 is the reflecting surface 4a. The reflecting surface 4a is also a parabolic surface which is a curved surface obtained by rotating a parabola with the optical axis passing through the light source 2 as a symmetric axis, and the focal point is the position of the light source 2. It is.

  As for the reflecting member 4, the light source 2 side is a light incident side on which light is incident, and the opposite side is a light emitting side for emitting light. On the light incident side, for example, a substantially hemispherical space 8 that is convex toward the light emitting side can be provided in order to increase the amount of light taken in. Further, on the light emitting side, a linear polarizer 5 is arranged without a retardation plate provided on the light incident side of the linear polarizer separately from the linear polarizer in the conventional light source device, for example, without a quarter wavelength plate. Is done. In addition, as shown in a modification in FIG. 7, the reflecting member 4 does not necessarily have the space portion 8.

  As for the light source device 1, similarly to the light source device 1 of the first embodiment, the light source 2 has at least an LED element 21, and the LED element 21 is a surface light source that emits surface light although it is small unlike a point light source. It is. Therefore, the light emitted from the surface light source becomes light emitted at an angle slightly deviated from the optical axis by the reflecting surface 4a. The emitted light is transmitted by the linear polarizer 5 while light having a predetermined linear polarization component is transmitted and light having an orthogonal polarization component is reflected. However, deviation from regular reflection occurs, and deviation occurs in the reflection position and polarization direction. That is, the non-polarized light emitted from the light source 2 is totally reflected by the outer peripheral side surface that is the reflecting surface 4a of the reflecting member 4 and reaches the linear polarizer 5, and the transmitted light component that is a predetermined linearly polarized component is a straight line. The light passes through the polarizer 5 and other polarized components are reflected. The reflected light does not return to the focal position of the reflecting surface 4a, but returns to a position slightly deviated from the focal position. The reflected light that has returned to a position slightly deviated from the focal position is re-emitted and repeatedly totally reflected in all directions by the reflecting surface 4a.

  By this re-emission and repeated reflection, the light is gradually converted to include a transmitted light component which is a predetermined linearly polarized light component. This transmitted light component is gradually transmitted through the linear polarizer 5 in the process of re-emission and repeated reflection. As a result, according to the light source device 1, it is possible to efficiently emit linearly polarized light having a uniform polarization direction. Moreover, according to the light source device 1, since the polarization conversion is performed by re-emission or repeated reflection, a retardation plate provided separately from the linear polarizer in the conventional light source device, for example, a quarter wavelength plate can be omitted. By omitting the retardation plate, the amount of emitted light can be increased and the structure can be simplified. Further, the cost can be reduced.

  The constituent material of the reflecting member 4 may be any material as long as it has translucency and can reflect light by total reflection. In addition to a general glass material mainly composed of silicon dioxide, a phosphate glass Bismuth glass, translucent resin and the like.

Examples of the phosphoric acid-based glass include P ₂ O ₅ : 26.2%, B ₂ O ₃ : 9.8%, BaO: 0.8%, Li ₂ O: 21. 2%, Na ₂ O: 4.4%, K ₂ O: 5.5%, Bi ₂ O ₃ : 4.6%, TiO ₂ : 5.3%, Nb ₂ O ₅ : 16.4%, WO _3: containing 5.8%, those refractive index _{n d} is 1.82.

The bismuth glass, in weight percent on the oxide _{basis, P 2 O 5: 10~18%} , Bi 2 O 3: 37~64%, Nb 2 O 5: 5~25%, Na 2 O: 4. 1 super _{~10%, K 2 O: 0~2} %, WO 3: less than 0 to 20% TiO _2: 0 to 3% and _B 2 _{O 3:} contains 0-2%, the refractive index _{n d} In which is 1.98 or more.

Examples of the translucent resin include acrylic resin, diethylene glycol bisallyl carbonate resin, polystyrene, aromatic polycarbonate resin, co-polymerization of dimethacrylate having a nuclear halogen-substituted aromatic ring and a monofunctional monomer having an aromatic ring. Copolymer, copolymer of polyisocyanate and polythiol, methyl methacrylate / styrene resin, tricyclo [5.2.1.0 ^2,6 ] deca-8-yl methacrylate / styrene resin, tricyclomethacrylate [5.2 1.0 ^2,6 ] Dec-8-yl / styrene / crosslinkable polyfunctional monomer copolymer, aromatic ring-containing di (meth) acrylate / aromatic ring-containing monomer / hydroxyl group-containing monomer Polymer, aromatic ring-containing di (meth) acrylate / aromatic ring-containing monomer / epoxy group-containing monomer copolymer, nuclear halogen-substituted aromatic ring and al Di (meth) acrylate containing a xylene glycol group / aromatic ring-containing monomer / copolymer or compound containing an aromatic ring and an epoxy group / styrene derivative / ethylene glycol dimethacrylate / specific diacrylate compound / specific epoxy Examples thereof include a copolymer of modified di (meth) acrylate.

  The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be added to the above-described embodiments without departing from the scope of the present invention. it can. For example, in the above-described embodiment, the example in which the linear polarizer 5 is provided directly on the light emitting side of the reflecting member 4 has been described, but the linear polarizer 5 may be provided via a translucent substrate or the like for supporting the linear polarizer 5. Good. Moreover, although the said embodiment demonstrated the example which provided the light quantity adjustment film 7 directly in the linear polarizer 5, the light quantity adjustment film 7 was provided in the translucent board | substrate etc. which support the above-mentioned linear polarizer 5. FIG. It may be provided. In addition, the present invention is suitably used for a liquid crystal projector using, for example, a transmissive or reflective liquid crystal panel, but the apparatus to which the present invention is applied is not necessarily limited to this, and an apparatus using linearly polarized light. If it is, it will not specifically limit.

Hereinafter, the light source device of the present invention will be described more specifically with reference to examples.
About the light source device of Examples 1-3 shown below, the light quantity, the illumination intensity position dependence, and the luminous intensity angle dependence were calculated | required by simulation. Note that the illuminance position dependency and the luminous intensity angle dependency were simulated in two ways: when the distance from the light source is 12.5 mm and when it is 40 mm. Examples 1 and 2 correspond to examples of the present invention, and example 3 corresponds to a comparative example of the present invention.

(Example 1)
As shown in FIG. 1, a substrate on which a light source is arranged, a reflecting member provided on the substrate so as to surround the light source, and a reflective linear polarizer provided on the light emitting side of the reflecting member; And a light source device having a potting part covering the light source. The light source is composed of an LED element and a phosphor layer provided so as to cover the LED element. The light amount adjustment film was not provided.

  The LED element had a square shape with a side of 2 mm and a thickness of 0.12 mm. The phosphor layer had a square shape with one side of 2.5 mm and a thickness of 0.6 mm. The potting part was a hemisphere with a diameter of 6 mm and made of silicone resin. The reflecting member is a cylindrical body made entirely of aluminum, and the reflecting surface is a parabolic surface with the position of the light source as a focal point and is in a mirror state. The diameter of the opening on the light incident side was 6 mm, the diameter of the opening on the light emitting side was 12 mm, and the length from the opening on the light incident side to the opening on the light emitting side was 12 mm. The linear polarizer was subjected to double-sided AR treatment on DBEF (trade name, manufactured by Sumitomo 3M).

(Example 2)
The light source device was the same as that of Example 1 except that a light amount adjusting film was provided on the light incident side surface of the linear polarizer. The light amount adjusting film is a reflective film made of a dielectric multilayer film having a reflectance of 50% and a transmittance of 50%, and is specifically arranged at the central portion of the linear polarizer, specifically, at the light emitting side opening of the reflecting member. A circular shape with a diameter of 1 mm was provided at a position on the center.

(Example 3)
The light source device was the same as Example 1 except that a quarter-wave plate was provided between the reflecting member and the linear polarizer.

  Table 1 shows the light amounts of the light source devices of Examples 1 to 3. Also, the illuminance position dependency and luminous intensity angle dependency of the light source device of Example 1 are shown in FIGS. 8 and 9, the illuminance position dependency and luminous intensity angle dependency of the light source device of Example 2 are shown in FIGS. The illuminance position dependency and luminous intensity angle dependency of the apparatus are shown in FIGS.

  In addition, the light quantity of the light source device is shown as the emitted light quantity when the emitted light quantity of the light source composed of the LED element and the phosphor layer is 100% as a reference. The illuminance position dependency is based on the position of the central part of the linear polarizer, specifically, the position on the central part of the opening on the light emitting side of the reflecting member as 0 mm as a reference. The relationship was shown. The light intensity angle dependency indicates the relationship between the angle from the optical axis and the light intensity when the optical axis passing through the light source is 0 degree. The amount of light loss in the linear polarizer and the quarter wavelength plate was not considered.

  From the results of Table 1, it can be seen that the light source devices of Examples 1 and 2 that do not have a quarter wavelength plate can increase the amount of light compared to the light source device of Example 3 that has a quarter wavelength plate. Further, in the light source device of Example 1 in which the light amount adjustment film is not provided, when the distance from the light source is close to 12.5 mm as shown in FIG. 8, the illuminance at the central portion of the linear polarizer, that is, the position of 0 mm is high. However, the light source device of Example 2 provided with the light amount adjustment film can be made uniform by lowering the illuminance at the central portion of the linear polarizer as shown in FIG.

  DESCRIPTION OF SYMBOLS 1 ... Light source device, 2 ... Light source, 3 ... Board | substrate, 4 ... Reflection member, 5 ... Linear polarizer, 6 ... Potting part, 7 ... Light quantity adjustment film, 8 ... Space part, 21 ... Light emitting diode element, 22 ... Phosphor layer

Claims (7)

A light source having a light emitting diode element;
A reflective member having a reflective surface surrounding the light source;
A light source device, comprising: a reflective linear polarizer provided on a light emitting side of the reflecting member without a retardation plate.   The light source device according to claim 1, wherein the reflection member is a cylindrical body, and an inner surface of the cylindrical body becomes the reflection surface.   2. The light source device according to claim 1, wherein the entire reflecting member is uniformly formed of a translucent material, and an outer peripheral side surface thereof is the reflecting surface.   2. A light amount adjusting film that absorbs or reflects a part of light incident on the linear polarizer or light emitted from the linear polarizer on a central portion of one of the linear polarizers on the main surface side. 4. The light source device according to any one of items 1 to 3. The inner surface shape of the reflecting member is a paraboloid, and the shape is r ² = 4az.
r: radius from the central axis of the paraboloid a: focal position z: central axis (exit side is positive)
The light source device according to claim 1, wherein the position of the incident side opening of the reflecting member is substantially a focal point. The focal position a of the reflecting member is
0.125 mm ≤ a ≤ 3.75 mm
S ₂ / S ₁ ≧ 10 where S ₁ and S ₂ are the opening areas on the incident side and the exit side, respectively.
The light source device according to claim 5, wherein: The length L of the reflecting member is
1.475mm ≤ L ≤ 163mm
The light source device according to claim 1, wherein the light source device is a light source device.

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