JP2006286608A - Planar illumination light source and planar illumination device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light and thin planer illumination light source, having improved planar light guiding action although adopting a light guide-less structure, preventing generation of lighting spot and unevenness in chromaticity, having high brightness, uniform light emission, and high color mixing properties with proper balance, with small power consumption. <P>SOLUTION: The planar illumination light source has one or more of point light sources 26, arranged on a holding base plate and a cylindrical lens covering the light observation side of the point light sources. The cylindrical lens has a concave lens function 22 in the vertical direction (y-direction) with respect to the holding base plate, and a convex lens function 24 at least in the direction of a part of horizontal direction (x-direction). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a planar illumination light source and a planar illumination device, and more specifically, a planar letter used for a channel letter, a backlight light source of a liquid crystal display element used for image display such as a computer, a word processor, and a television. It relates to an irradiation light source.

In recent years, liquid crystal display devices having a backlight light source have begun to be used in portable electronic devices or various image display devices. A liquid crystal display device is usually composed of a light guide plate, a liquid crystal cell, a prism sheet, a diffusion sheet, a backlight light source, and the like (for example, Patent Document 1). However, with an increase in the size of display devices using a liquid crystal display device, liquid crystal display devices that do not use a light guide plate, which has been an essential component of conventional liquid crystal display devices, have begun to be developed. This is because it is difficult to produce a large light guide plate, and the large display device is reduced in weight and thickness.
In general, the backlight light source is used as a planar light source by using a linear light source in which a core light source is formed of an FL (fluorescent lamp) or the like. However, in consideration of low power consumption and long life, a light emitting diode whose brightness is rapidly increasing is about to be used as a backlight light source.

On the other hand, FL and the like have been used not only in display devices but also in display refrigerators and the like that display drinking water and the like installed in convenience stores and the like. Since FL has poor temperature characteristics at low temperatures, there was a contradiction that the vicinity of FL had to be heated by a heater, even though it was a refrigerator. Therefore, in order to avoid such a contradiction and to consider low power consumption and long life, replacement of light sources such as FL (fluorescent lamp) with light emitting diodes has begun.
JP 2003-57622 A

  In a display device or the like, when a light guide plate-less structure is adopted as a planar irradiation light source, the effect of guiding the light in a planar manner is weakened. In the backlight light source, a linear light source such as FL is used as a core light source, and a planar, that is, a two-dimensional light source is obtained. Therefore, if the core light source is a linear light source, that is, one-dimensional, it is only necessary to increase the dimension by one.

  However, if a point light source, that is, a zero-dimensional light source is used as the core light source, it is necessary to increase the dimension by 2, so that it is difficult to realize appropriate luminance and uniform light emission. That is, when a light-emitting diode is used for a planar light source having a light guide plate-less structure, a portion where the light-emitting diode exists immediately below becomes a bright spot, and it is difficult to uniformly emit light within the surface. Further, when red, blue, and green light emitting diode chips are separately packaged and combined into white light, chromaticity unevenness occurs.

  Moreover, in the refrigerator for a display, the whole surface is glassed and a light source cannot be put on this glass part. Therefore, a structure in which light emitting diodes are installed in a tandem manner at the end of a sliding door is unavoidable. In this case, it is attempted to attach a side emitter lens or a Lambertian lens for each light emitting diode and emit light in a wide range, but due to the optical path difference derived from the difference in physical distance from the light emitting diode, It is difficult to prevent the generation of bright lines and bright spots.

The present invention is a planar illumination light source having one or more point light sources arranged on a holding substrate and a cylindrical lens covering the emission observation side of the point light source, the cylindrical lens being attached to the holding substrate A planar irradiation light source having a concave lens function in the vertical direction (y direction) and having a convex lens function in at least one horizontal direction (x direction) is provided.
In this planar irradiation light source, the point light source is preferably located between a portion having a convex lens function of the cylindrical lens and the focal point of the portion.
The point light source emits light having a light distribution characteristic having a cosine curve with respect to the xy direction, and the light transmitted through the cylindrical lens has a light distribution characteristic having two peaks symmetrically with respect to the xy direction. It is preferable.

Further, the cylindrical lens preferably has a hollow structure having a space between the point light source, and the cylindrical lens is made of a material having a refractive index different from that of a portion having a concave lens function and a portion having a convex lens function, It is preferable that the material forming the part having the concave lens function has a lower refractive index than the material forming the part having the convex lens function.
Moreover, it is preferable that a diffusing agent is mixed only in a portion having a concave lens function of the cylindrical lens.

According to the planar irradiation light source of the present invention, even when the light guide plate-less structure is adopted, the effect of guiding the light in a planar shape can be improved. In addition, generation of bright lines and bright spots and uneven chromaticity can be prevented, and appropriate luminance and uniform light emission can be realized. In addition, a planar irradiation light source having high brightness, uniform light emission, and high color mixing can be obtained. Thereby, the planar irradiation light source with light weight, thinness, and low power consumption can be provided.
In particular, when the planar illumination light source of the present invention is arranged at regular intervals in the x direction, uniform planar illumination can be performed over a wider range. Further, when used in a show window or a display case, it is possible to uniformly illuminate the displayed product and display the product without generating bright lines or bright spots.

The best mode for carrying out the present invention will be described below with reference to the drawings. However, the form shown below illustrates the planar irradiation light source and the planar irradiation apparatus for embodying the technical idea of the present invention, and is not limited to the following. Further, the size and positional relationship of the members shown in the drawings are exaggerated for clarity of explanation.
The planar irradiation light source of the present invention covers one or more point light sources arranged on the holding substrate and the light emission observation side of the point light source, and has a concave lens function in the vertical height direction (y direction) with respect to the holding substrate. And a cylindrical lens having a convex lens function in at least one horizontal direction (x direction).

  The holding substrate may be made of any material as long as it holds the point light source and the cylindrical lens. For example, an aluminum base substrate, a copper base substrate, a glass epoxy substrate, etc. are mentioned. An aluminum base substrate is one in which the mounting surface side of an aluminum plate is covered with an insulating film, and a wiring pattern for a point light source is provided on this insulating film, or one that is actually wired . The copper base substrate refers to an aluminum base substrate in which aluminum is replaced with copper. The glass epoxy substrate refers to a substrate in which aluminum is replaced with a plate made of glass epoxy resin. The holding substrate may be an integral type or may be composed of a plurality of components. It is preferable to devise heat dissipation such as a fan on the back surface of these substrates.

  Various point light sources can be used, and a light emitting diode is preferable from the viewpoint of high luminance and energy saving. This is because a planar illumination light source with low power consumption and long life is possible. In addition, the luminous efficiency can be maintained and improved even when used in a cold environment such as in a refrigerator. Package types include shell type and surface mount type (for example, top view type, side view type, etc.), but surface mount type is preferred, and top view type is particularly preferred from the viewpoint of high brightness and high heat dissipation. Is preferred.

  In particular, it is preferable that the point light source has an alignment characteristic in which the light emitted therefrom has a cosine curve with respect to the xy direction. A light distribution characteristic with respect to the xy direction has a cosine curve means that light is emitted in a circular plane shape, and the position facing the point light source has the strongest light intensity, and as it goes from the facing position to the side. This means that the light is attenuated and cannot be detected when it is shifted 90 ° laterally with respect to the facing direction, and it shows a cosine curve-like orientation characteristic. Such a light distribution characteristic is also called a Lambertian light distribution characteristic (see FIG. 9, the facing direction is shown as 0 °).

  A light-emitting diode, which is a preferred example of a point light source, is a light-emitting diode chip packaged with a sealing resin, and the package is coated with a fluorescent material or the like that converts the wavelength of light from the light-emitting diode chip. It is preferable that they are arranged as described above. Thereby, regardless of the wavelength of light from the light-emitting diode chip, light of any wavelength can be obtained, and light of a plurality of wavelengths can be easily mixed. In particular, it is preferable to engrave light from the light emitting diode chip and convert it into a long wavelength because the light emission efficiency is good. As a result, high brightness white light can be obtained. In addition, two or more light emitting diode chips may be packaged in the light emitting diode, and one type of fluorescent material may be a single layer, two or more types of fluorescent materials may be mixed to form a single layer, and separated. It may be packaged in a single layer form, in a mixed or separated state and in a laminated form.

  The fluorescent material preferably has a central particle size in the range of 1 to 100 μm, in the range of 6 to 50 μm, and in the range of 15 to 30 μm from the viewpoint of high light absorption and conversion efficiency and a wide excitation wavelength width. Examples of the fluorescent substance include various substances such as the following phosphors.

(Aluminum oxide phosphor)
As described in WO03 / 034508, the aluminum oxide-based phosphor contains Al and contains at least one element selected from Y, Lu, Sc, La, Gd, Tb, Eu, and Sm, and Ga. And a phosphor activated by at least one element selected from rare earth elements and excited by visible light or ultraviolet light emitted from the light-emitting diode chip to emit light. It is a phosphor.

For example, YAlO ₃ : Ce, Y ₃ Al ₅ O ₁₂ : Ce, Y ₄ Al ₂ O ₉ : Ce, (Y _0.8 Gd _0.2 ) ₃ Al ₅ O ₁₂ : Ce, Y ₃ (Al _0.8 Ga _0.2 ) ₅ O ₁₂ : Ce, Tb _2.95 Ce _0.05 Al ₅ O ₁₂ , Y _2.90 Ce _0.05 Tb _0.05 Al ₅ O ₁₂ , Y _2.94 Ce _0.05 Pr _0.01 Al ₅ O ₁₂ , Y _2.90 Ce _0.05 Pr _0.05 Al ₅ O _{12 and the} like. In particular, Y is an yttrium / aluminum / garnet phosphor (hereinafter referred to as “YAG phosphor”) which is one of two or more types of aluminum oxide phosphors activated by Ce or Pr and having different compositions. ), in _{particular, (Re 1-x Sm x} ) 3 (Al 1-y Ga y) 5 O 12: Ce (0 ≦ x <1,0 ≦ y ≦ 1, where, Re is, Y, Gd, from La And at least one element selected from the group consisting of:

(Lutetium / Aluminum / Garnet phosphor)
The lutetium / aluminum / garnet phosphor has a general formula (Lu _1-ab R _a M _b ) ₃ (Al _1-c Ga _c ) ₅ O ₁₂ (provided in JP-A-2005-8844). , R is at least one rare earth element in which Ce is essential M is at least one element selected from Sc, Y, La, Gd, and 0.0001 ≦ a ≦ 0.5, 0 ≦ b ≦ 0.5, 0.0001 ≦ a + b <1, 0 ≦ c ≦ 0.8.) For example, the composition formula is represented by (Lu _0.99 Ce _0.01 ) ₃ Al ₅ O ₁₂ , (Lu _0.90 Ce _0.10 ) ₃ Al ₅ O ₁₂ , (Lu _0.99 Ce _0.01 ) ₃ (Al _0.5 Ga _0.5 ) ₅ O ₁₂ Is mentioned.

(Nitride phosphor)
The nitride-based phosphor includes N and contains at least one element selected from Be, Mg, Ca, Sr, Ba, and Zn, and C, Si, Ge, as described in WO 03/034508. , Sn, Ti, Zr, and Hf, and a phosphor activated with at least one element selected from rare earth elements. For example, Sr ₂ Si ₅ N ₈ : Eu, Pr, Ba ₂ Si ₅ N ₈ : Eu, Pr, Mg ₂ Si ₅ N ₈ : Eu, Pr, Zn ₂ Si ₅ N ₈ : Eu, Pr, SrSi ₇ N _{10 : Eu, Pr, BaSi 7 N} 10: Eu, Ce, MgSi 7 N 10: Eu, Ce, ZnSi 7 N 10: Eu, Ce, Sr 2 Ge 5 N 8: Eu, Ce, Ba 2 Ge 5 N 8: _{Eu, Pr, Mg 2 Ge 5} N 8: Eu, Pr, Zn 2 Ge 5 N 8: Eu, Pr, SrGe 7 N 10: Eu, Ce, BaGe 7 N 10: Eu, Pr, MgGe 7 N 10: Eu _{, Pr, ZnGe 7 N 10:} Eu, Ce, Sr 1.8 Ca 0.2 Si 5 N 8: Eu, Pr, Ba 1.8 Ca 0.2 Si 5 N 8: Eu, Ce, Mg 1.8 Ca 0.2 Si 5 N 8: Eu, Pr _{, Zn 1.8 Ca 0.2 Si 5 N} 8: Eu, Ce, Sr 0.8 Ca 0.2 Si 7 N 10: Eu, _{a, Ba 0.8 Ca 0.2 Si 7} N 10: Eu, La, Mg 0.8 Ca 0.2 Si 7 N 10: Eu, Nd, Zn 0.8 Ca 0.2 Si 7 N 10: Eu, Nd, Sr 0.8 Ca 0.2 Ge 7 N 10: Eu, Tb, Ba _0.8 Ca _0.2 Ge ₇ N ₁₀ : Eu, Tb, Mg _0.8 Ca _0.2 Ge ₇ N ₁₀ : Eu, Pr, Zn _0.8 Ca _0.2 Ge ₇ N ₁₀ : Eu, Pr, Sr _0.8 Ca _0.2 Si ₆ GeN _{10: Eu, Pr, Ba 0.8} Ca 0.2 Si 6 GeN 10: Eu, Pr, Mg 0.8 Ca 0.2 Si 6 GeN 10: Eu, Y, Zn 0.8 Ca 0.2 Si 6 GeN 10: Eu, Y, Sr 2 Si 5 N ₈ : Pr, Ba ₂ Si ₅ N ₈ : Pr, Sr ₂ Si ₅ N ₈ : Tb, BaGe ₇ N ₁₀ : Ce, (Ca, Sr, Ba) Si ₂ O ₂ N ₂ : Eu, CaSiAlN ₃ : Eu, Examples include so-called sialon phosphors. There.

(Oxynitride phosphor)
_{L x M y O z N [} (2 / 3x + (4/3) y- (2/3) z): R
(Wherein L is at least one element selected from the group consisting of Be, Mg, Ca, Sr, Ba, Zn, and M is a group consisting of C, Si, Ge, Sn, Ti, Zr, and Hf) At least one element selected from the group consisting of nitrogen, O is oxygen, and R is a rare earth element, x, y, and z satisfy the following numerical values: x = 2, 4.5 ≦ y ≦ 6, 0.01 <z <1.5 or x = 1, 6.5 ≦ y ≦ 7.5, 0.01 <z <1.5 or x = 1, 1.5 ≦ y ≦ 2.5 1.5 ≦ z ≦ 2.5)

(Alkaline earth metal silicate phosphor)
As described in JP-A-2005-85895, (2-xy) SrO.x (Ba, Ca) O. (1-abbcd) SiO ₂ .aP ₂ O ₅ bAl ₂ O ₃ cB ₂ O ₃ dGeO ₂ : yEu ²⁺ (where 0 <x <1.6, 0.005 <y <0.5, 0 <a, b, c, d <0.5) .)
(2-x-y) BaO · x (Sr, Ca) O · (1-a-b-c-d) SiO 2 · aP 2 O 5 bAl 2 O 3 cB 2 O 3 dGeO 2: yEu 2+ ( In the formula, 0.01 <x <1.6, 0.005 <y <0.5, 0 <a, b, c, d <0.5.) Me (3-xy) MgSi ₂ O ₃ : xEu, yMn (in the formula, 0.005 <x <0.5, 0.005 <y <0.5, Me represents Ba and / or Sr and / or Ca).

(Other phosphors)
(1) Eu, Mn or alkaline earth halogen apatite phosphor activated by Eu and Mn; for example, M ₅ (PO ₄ ) ₃ (Cl, Br): Eu (where M is Sr, Ca, Ba, At least one selected from Mg), Ca ₁₀ (PO ₄ ) ₆ ClBr: Mn, Eu and the like.
(2) Eu, Mn or alkaline earth aluminate phosphor activated with Eu and Mn; for example, BaMg ₂ Al ₁₆ O ₂₇ : Eu, BaMg ₂ Al ₁₆ O ₂₇ : Eu, Mn, Sr ₄ Al ₁₄ O ₂₅ : Eu, SrAl ₂ O ₄ : Eu, CaAl ₂ O ₄ : Eu, BaMgAl ₁₀ O ₁₇ : Eu, BaMgAl ₁₀ O ₁₇ : Eu, Mn, etc.
(3) A rare earth oxysulfide phosphor activated with Eu; for example, La ₂ O ₂ S: Eu, Y ₂ O ₂ S: Eu, Gd ₂ O ₂ S: Eu, and the like.
(4) (Zn, Cd) S: Cu, Zn ₂ GeO ₄ : Mn, 3.5 MgO · 0.5 MgF ₂ · GeO ₂ : Mn, Mg ₆ As ₂ O ₁₁ : Mn (Mg, Ca, Sr, Ba _{) Ga 2 S 4: Eu,} Ca 10 (PO 4) 6 FCl: Sb, Mn,
(5) An organic complex phosphor activated with Eu.

  The light emitted from the point light source is preferably white light. For example, when only one light emitting diode is used, it is preferable to emit white light. When two or more light emitting diodes are used, ones that emit white light may be combined, or each light emitting diode has a different emission color, but may emit white light as a whole. For example, when the light emission colors of the light emitting diodes are different such as red, green, and blue, any mixed color light can be obtained by arranging the light emitting diodes having different light emission colors in the z direction. When one light emitting diode is constituted by a plurality of light emitting diode chips, a plurality of light emitting diode chips having different emission colors and one or more fluorescent materials are used, and one light emitting diode is white. You may get light. When white light is realized by combining a plurality of light emitting diodes having different emission colors, it is preferable to mix a diffusing agent in the cylindrical lens as described later in order to improve color mixing.

  The cylindrical lens is a cylindrical lens and has a hollow structure for arranging a light source inside the cylinder. With such a shape, the light emission observation side of the point light source is covered. By adopting a hollow structure, it is possible to develop a concave lens function and a convex lens function by the interaction between the inner surface and the outer surface of the cylindrical lens. The light emission observation side refers to the side where the planar illumination light source can be viewed directly, in other words, the side facing the holding substrate.

  The cylindrical drill lens has a concave lens function in the vertical direction (y direction) with respect to the holding substrate, and has a convex lens function in at least one horizontal direction (x direction). The concave lens function refers to a function of diverging light by the interaction between the inner surface and the outer surface of the cylindrical lens. The convex lens function refers to a function of focusing a light beam by the interaction between the inner surface and the outer surface of the cylindrical lens. By having such a function, a planar illumination light source can be realized using a point light source. In other words, since the core light source is a point light source, the presence of the point light source can be confirmed when looking directly at the planar illumination light source through the cylindrical lens, but the surface illuminated by the planar illumination light source has no uneven brightness, The irradiated surface has a uniform illuminance distribution, although no bright spots or bright lines are generated and the surface does not emit light uniformly. In the cylindrical lens, it is suitable that the focal position of the part having one convex lens function is located below the holding substrate surface or from the center of the hollow structure of the cylindrical lens to the part having the other convex lens function. ing.

  In this specification, as shown in FIG. 1, the x direction is a direction that is horizontal to the holding substrate and is perpendicular to the longitudinal direction of the cylinder, and the y direction is a direction that is perpendicular to the holding substrate. Point to. The z direction to be described later is a horizontal direction with respect to the holding substrate and indicates a longitudinal direction of the cylinder. The xyz directions are orthogonal to each other. As will be described later, when the shape extending in the longitudinal direction of the cylinder is other than a linear shape, the z direction can be simply defined as a direction orthogonal to both the x direction and the y direction. However, the vertical direction (y direction) and the horizontal direction (x direction) are not necessarily taken strictly, but can be taken as meaning the direction facing the holding substrate and the directions on both sides thereof.

  The cylindrical lens may be formed of any material as long as it has translucency and can express the lens function. In particular, it is preferably formed of a material having a certain level of translucency with respect to light having a wavelength between near ultraviolet, visible light, and near infrared. Specifically, acrylic resin, polycarbonate resin, amorphous polyolefin resin, polystyrene resin, norbornene resin, cycloolefin polymer (COP), epoxy resin, silicone resin, acrylonitrile from the viewpoints of translucency and processability -Butadiene / styrene resin (ABS resin), sapphire, quartz, soda glass, borosilicate glass, silica glass, oxynitride glass, rare earth glass and the like are suitable. Among these, acrylic resins are preferable because they have high translucency and are less likely to cause yellowing due to light deterioration, and thus are less likely to cause a decrease in output due to changes over time. Moreover, since the polycarbonate resin is excellent in impact resistance, it is suitable for use in a mechanically poor environment. As the refractive index of the cylindrical lens, for example, a refractive index of 1.3 to 2.0 is preferably used.

  The entire cylindrical lens may be formed of the same material, but it is preferable that the cylindrical lens is made of a material having different refractive indexes at a portion having a concave lens function and a portion having a convex lens function. Specifically, it is preferable that the material forming the part having the concave lens function has a lower refractive index than the material forming the part having the convex lens function. Since the lens function is expressed by the difference in refractive index and the higher refractive index can enhance the lens function, it is preferable that the part having the convex lens function has a higher refractive index. The same applies to the part having the concave lens function. However, if the refractive index is too high, total reflection tends to occur, and the light extraction efficiency decreases. Therefore, the optimum value of the refractive index is different between the part having the convex lens function and the part having the concave lens function. Accordingly, it is preferable to appropriately adjust the optimum material and refractive index according to the orientation characteristics of the intended planar irradiation light source.

  In the cylindrical lens, depending on the point light source used, a diffusing agent may be mixed only in a portion having a concave lens function. Examples of the diffusing agent herein include one or more of barium titanate, titanium oxide, aluminum oxide, silicon oxide, calcium carbonate, white carbon, talc, magnesium carbonate, and the like. As a result, light can be effectively diffused at the concave lens portion, and as a result, bright spots and bright lines that are most likely to occur in the portion directly above the point light source can be prevented. In addition, when a multicolor light source is used as a point light source, it is expected to improve the color mixing property, and generation of bright spots and bright lines can be suppressed. On the other hand, when a diffusing agent is used, light is diffused even though the optical characteristics are controlled by the lens function based on the shape of the cylindrical lens. Therefore, it is preferable to mix the diffusing agent while limiting to the concave lens portion which is a portion having a short optical path length. Thereby, the color mixing property can be enhanced without deteriorating the function of the convex lens portion. Furthermore, the above-mentioned fluorescent substance may be mixed in the whole or part of the cylindrical lens, or may be applied to all or part of the inner surface and / or outer surface thereof.

  The shape of the cylinder is not particularly limited, and may be a linear shape, a curved shape, an arch shape, a broken line shape, an L shape, a circular shape, or the like extending in the longitudinal direction. Further, when only one point light source is covered, it may be a dome shape, a cup shape or the like having a gap in the center portion. Further, regardless of the number of point light sources, the end portion thereof preferably has a shape covering the point light source (such as a dome or cup shape). The cylindrical lens may be an integral type or may be separated into individual pieces and mechanically / physically separate, but a plurality of cylindrical lenses may be connected and functionally integrated.

  In the planar irradiation light source of the present invention, as shown in FIGS. 1 to 4, the point light source may have two or more plural light sources arranged in a row (aligned in the longitudinal direction of the holding substrate) on the holding substrate. However, as shown in FIGS. 5 to 8, only one may be arranged. These planar illumination light sources have different groups in the z direction but have the same shape in the xy plane (FIGS. 1 and 5 groups, FIGS. 2 and 6 groups, FIGS. 3 and 4). 7 group, FIG. 4 and FIG. 8 group). Each direction of xyz is as illustrated in FIG. 1 in each figure. In the drawing, the holding substrate is not shown.

  The cylindrical lenses shown in FIG. 1 and FIG. 5 are least likely to generate bright lines and dark lines because there are no curved surfaces in the concave lens portion and the convex lens portion in the xy plane. In this case, since the concave lens function is expressed only on the inner surface of the cylindrical lens, it is preferable to make the convex angle of the inner surface sharp.

  The cylindrical lens shown in FIGS. 2 and 6 exhibits a concave lens function on both the inner surface and the outer surface of the cylindrical lens, so that the concave lens function can be made stronger than the group in FIGS. 1 and 5. become.

The cylindrical lens shown in FIGS. 3 and 7 can have the most concave lens function. On the other hand, since the convex lens function is realized only on the inner surface, the convex lens function is relatively weak.
The cylindrical lens shown in FIGS. 4 and 8 is a Fresnel lens processed. Thereby, compared with other embodiment, thickness reduction and weight reduction are attained.

  In the present invention, the point light source is preferably arranged between a portion having a convex lens function of the cylindrical lens and the focal point of the portion. Since the cylindrical lens includes a portion having two convex lens functions in the x-direction, a portion having the convex lens function and a focal point of the portion are simultaneously provided with respect to the portions having both convex lens functions. It is preferable to arrange. By arranging at this position, the light that has passed through the cylindrical lens does not become parallel light and does not cross each other while maintaining the desired light collecting ability, and the light is diverged and the luminance unevenness of the light source is reduced. The influence can be reduced.

  Moreover, it is preferable that the light emitted from the planar illumination light source, that is, the light transmitted through the cylindrical lens has an alignment characteristic that is bilaterally symmetrical with respect to the xy direction and has two peaks. The light distribution characteristic is bilaterally symmetrical and has two peaks. The light distribution characteristic has two peaks of light emission intensity in a direction different from the facing direction, and is symmetric with respect to the facing direction on both sides of the facing direction. It refers to an orientation characteristic having a peak. Such light emission characteristics are also referred to as batwing light distribution characteristics (FIG. 10) and side emitter light distribution characteristics (FIG. 11). Thereby, a uniform illuminance distribution can be obtained over substantially the entire surface.

Example 1
In this embodiment, as shown in FIG. 12, an image display having a backlight light source using a planar illumination light source in which a cylindrical lens of the type shown in FIG. 1 and a light emitting diode having a Lambertian light distribution characteristic are combined. Configure the device.
The structure is such that a metal heat sink is used as the holding substrate to improve heat dissipation and to increase the current input to the light emitting diode.
By disposing the planar irradiation light source of the present invention on a metal heat sink for diffusing the heat of the light emitting diode and dissipating it to the outside air, by disposing at an appropriate interval determined from the distance between the light source and the irradiation surface and the light distribution characteristics, It is possible to achieve a light source device having a uniform illuminance distribution in which no bright line or dark line is seen on the irradiated surface.

Here, the irradiation surface refers to a diffusion plate, a prism sheet (not shown), a polarization conversion element plate (not shown) alone or a combination of them with a display plate (LCD, printing film, etc.). .
In addition, large items such as store signboards, display signs in tunnels, etc. can achieve the same effect with only the display board without the need for a diffusing plate or the like due to the strong interference effect between the planar illumination light sources. it can.
By using the planar illumination light source of the present invention as the backlight light source of this form, it becomes possible to reduce the distance between the light source and the illumination surface that normally has to be widened to prevent bright spots and bright lines, and the overall thickness of the apparatus is reduced. Can be achieved.

(Example 2)
In this embodiment, as shown in FIG. 13, a planar irradiation device for a display refrigerator installed in a convenience store or the like using a planar irradiation light source is configured.
The refrigerator has a height of 1600 mm, the interval between the columns at the end of the glass door is 762 mm (30 inches), the column rear surface is opposed to the irradiation surface, and the planar irradiation light source is installed in a row for the height. The distance from the display product surface that is the irradiation surface is 177.8 mm (7 inches).

  The cylindrical lens used here was injection molded with acrylic resin in x direction: 19.26 mm, y direction: 6.1 mm, z direction: 400 mm, and thickness in x direction (thickness of convex lens): 10 mm, y Thickness in direction (thickness of concave lens): 2 mm. A structure covering five light emitting diodes arranged at equal intervals (80 mm) per cylindrical lens was used. The light emitting diode is, for example, on the surface of the holding substrate and at the center in the hollow x direction of the cylindrical lens, that is, the focal point of the cylindrical lens having a convex lens function and the focal point of the cylindrical lens having a convex lens function. Arranged between. The brightness per one light emitting diode was 80 lm or more. For each column, four cylindrical lenses and 20 light emitting diodes are used.

The light distribution of the planar irradiation light source used here has two peaks in the vicinity of ± 80 degrees in the x direction, and is controlled so that the intensity is 10% or less of the peak at 0 degrees.
In FIG. 14, the irradiation surface illumination intensity distribution from each planar irradiation light source is shown. FIG. 14 shows the irradiation surface illuminance distribution for each row, and FIG. 15 shows the total irradiation surface illuminance distribution. As can be seen from FIG. 15, a uniform illuminance distribution can be obtained over substantially the entire surface.

By using such a planar illumination light source and having a display-type refrigerator having the above-described structure, a uniform illuminance distribution of 1000 lux on average can be achieved in which bright lines and dark lines are not seen on the display product surface.
By using the present invention, heating of the light source, which is necessary when using a normal FL (fluorescent lamp), is not required, and light is not emitted in the backward direction due to the function of the cylindrical lens. There is no longer any unpleasant glare that would enter the customer's sight.
In addition, when the FL is used, the front of the light source, that is, the back of the pillar is brightest and the center of the product shelf is illuminated darkly due to its omnidirectional characteristics. By using the present invention in this way, It is possible to irradiate evenly and brightly.

(Example 3)
Example 3 is a passage illumination light source device installed on a ceiling of a dam underground passage or the like using the planar irradiation light source according to the present invention. In such a place, outside light is completely blocked and the width of the road is such that one worker can move, so that the light intensity of the light emitting diode is sufficient for moving and working. In addition, since it is a place where maintenance is difficult, the merit of long life, which is a feature of the light-emitting diode, is greatly exhibited. In addition, the unique function of the light distribution characteristics of the invention makes it possible to illuminate not only the bottom surface but also the wall surface of the aisle, achieving a lighting device that can secure sufficient illuminance necessary for safety of movement and inspection / repair work. it can.

  INDUSTRIAL APPLICABILITY The present invention is used for various illuminations such as backlights for various display devices such as liquid crystal display devices that are remarkably required to be thin and lightweight, backlights for simple signboards, display refrigerators or display shelves, general illumination, and the like. be able to.

(A) is a side view showing one embodiment of the planar irradiation light source of the present invention, (b) is a perspective view, (c) is a transparent perspective view, (d) is an enlarged perspective view of the main part. (A) is a side view which shows another embodiment of the planar irradiation light source of this invention, (b) is a perspective view, (c) is a transparent perspective view, (d) It is an enlarged perspective view of the principal part. (A) is a side view which shows another embodiment of the planar irradiation light source of this invention, (b) is a perspective view, (c) is a transmission perspective view, (d) It is an enlarged perspective view of the principal part. (A) is a side view which shows another embodiment of the planar irradiation light source of this invention, (b) is a perspective view, (c) is a transmission perspective view, (d) It is an enlarged perspective view of the principal part. (A) is a side view of another embodiment of the planar irradiation light source of the present invention, (b) is a perspective view, (c) is a transparent perspective view. (A) is a side view of another embodiment of the planar irradiation light source of the present invention, (b) is a perspective view, (c) is a transparent perspective view. (A) is a side view of another embodiment of the planar irradiation light source of the present invention, (b) is a perspective view, (c) is a transparent perspective view. (A) is a side view of another embodiment of the planar irradiation light source of the present invention, (b) is a perspective view, (c) is a transparent perspective view. It is a graph showing a Lumbershan light distribution characteristic. It is a graph showing a batwing light distribution characteristic. It is a graph showing a side emitter light distribution characteristic. It is a perspective view showing the backlight light source using the planar irradiation light source of this invention. It is a perspective view showing the refrigerator for a display using the planar irradiation light source of this invention. It is a graph which shows the irradiation surface illumination intensity distribution of the planar irradiation light source per row used with the refrigerator for displays. It is a graph which shows the irradiation surface illumination intensity distribution of the planar irradiation light source of 3 rows total used with the refrigerator for displays.

Explanation of symbols

12, 22, 32, 42, 52, 62, 72, 82 Parts 14, 24, 34, 44, 54, 64, 74, 84 having a concave lens function Parts 16, 26, 36, 46, 56, having a convex lens function 66, 76, 86 Light emitting diode 123 Cylindrical lens 125, 133 Diffuser 127 Display panel 128 Heat sink 135 Drinking water 137 Shelf

Claims (6)

A planar irradiation light source having one or more point light sources arranged on a holding substrate and a cylindrical lens covering the emission observation side of the point light source,
The cylindrical lens is a planar irradiation light source having a concave lens function in the vertical direction (y direction) with respect to the holding substrate and having a convex lens function in at least a part of the horizontal direction (x direction).   The planar illumination light source according to claim 1, wherein the point light source is located between a portion having a convex lens function of the cylindrical lens and a focal point of the portion.   The point light source emits light having a light distribution characteristic having a cosine curve with respect to the xy direction, and light transmitted through the cylindrical lens has a light distribution characteristic having two peaks symmetrically with respect to the xy direction. Item 3. The planar irradiation light source according to Item 1 or 2.   The planar illumination light source according to any one of claims 1 to 3, wherein the cylindrical lens has a hollow structure having a space between the point light source and the cylindrical lens.   The cylindrical lens is made of a material having a refractive index different from that of a part having a concave lens function and a part having a convex lens function, and the material forming the part having the concave lens function has a refractive index higher than that of the material forming the part having the convex lens function. The planar irradiation light source according to claim 1, which is low. The planar irradiation light source according to any one of claims 1 to 5, wherein a diffusing agent is mixed only in a portion having a concave lens function of the cylindrical lens.

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