JP2015148730A - Light diffusion member for LED illumination and LED illumination device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve light emitting efficiency in an LED illumination tool, and further to improve light transmittance of a light diffusion member of an LED illumination cover or the like.SOLUTION: A light diffusion member of an LED illumination cover has a layer structure comprising a light transmission layer and light diffusion layer. The refraction index of the light transmission layer is equal to or more than the refraction index of the light diffusion layer, and the volume concentration of a light diffusion material in the light diffusion layer is 5% or more and less than 74%. Therefore, both diffusivity and transmittance of light are attained, and light emitting efficiency of an LED illumination device is improved.

Description

  The present invention relates to an illumination light diffusing member, and is particularly effective when applied to an illumination apparatus using a white LED module configured to include a phosphor exciting light emitting diode (LED) and a phosphor. It is about technology.

  Fluorescent lamps are widely used as illumination light sources, but have disadvantages such as the use of mercury, which is a harmful substance, and a short lifetime. For this reason, in recent years, illumination light sources using white LEDs (Light Emitting Diodes) have come to be used due to features such as no use of harmful substances, long life, and high luminous efficiency. In addition to the above, the illumination using the white LED has the following advantages.

  (1) Since direct current driving is possible, there is no flickering that occurs with conventional alternating current fluorescent lamps, which is easy on the eyes. (2) In the illumination using the LED, the amount of ultraviolet rays generated is smaller than that of a conventional fluorescent lamp, the influence on the human body is small, and material deterioration can be suppressed. (3) Since glass used in conventional fluorescent lamps is not used, there is little danger even if it falls from the ceiling.

  Because of these characteristics, light-emitting elements configured using light-emitting diodes (LEDs) as light sources are attracting attention as illumination light sources for home lighting and business use, and research and development have been actively promoted in recent years.

  These illumination light sources are configured by arranging a plurality of white LED modules having a size of about several mm □. Since each module is a point light source and the light from each module has high luminance, glare and glare cannot be avoided with a configuration in which LED modules are simply arranged. For this reason, in ordinary lighting fixtures, light diffusers such as shade covers that diffuse light on the surface side of the fixtures and light covers that contain a light diffusing material called a glove are placed to achieve uniform emission intensity within the light emitting surface. This reduces glare. However, in an illumination cover containing this light diffusing material, the light intensity can be made uniform by improving the light scattering property, but the light transmittance is reduced. Since the light diffusivity and the light transmittance are in a trade-off relationship as described above, it is an important issue to achieve both the light diffusibility and the light transmittance.

  Conventionally, a light diffusing member such as a lighting cover has been proposed in which polymer fine particles as a light diffusing material are mixed with a transparent resin such as a polycarbonate at a concentration of several wt% (Patent Document 1) (patent document 1). Document 2), further performance improvement is required.

JP2011-57925A JP 2013-133349 A

  In the present invention, in order to realize a high luminous efficiency LED lighting fixture, it is intended to achieve both the light diffusibility and the light transmittance of the light diffusing member by a novel light diffusing member structure for illumination.

  In order to solve the above problems, by controlling the dispersibility of the light diffusing material and adopting a light diffusing member structure composed of a light transmitting layer and a light diffusing layer, loss due to light diffusion is suppressed and light diffusing properties and light are reduced. Realized both transmittance.

  Among the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.

  The light diffusion member for illumination in the present invention has a light diffusion layer in which a light diffusion material is dispersed in a transparent resin, and the volume concentration (filling rate) of the light diffusion material in the light diffusion layer is 5% or more and 74%. By making it less than, both light diffusibility and light transmittance were realized. Furthermore, using a two-layer structure of a light transmission layer and a light diffusion layer, the light transmission layer is disposed so as to face the LED module, and the refractive index (n1) of the light transmission layer and the refractive index of the transparent resin constituting the light diffusion layer (N2) reduces the loss of LED light by satisfying n1 ≧ n2.

It is explanatory drawing of the light-diffusion member for LED illumination which is one embodiment of this invention. It is a typical drawing which shows the structure of the light diffusing member for illumination. It is drawing explaining a half value angle. It is drawing which shows the relationship between the transmittance | permeability and a half value angle. 1 is a schematic drawing showing an example of a general illumination light diffusing member. It is typical drawing which shows an example of the light-diffusion member for illumination in this invention. It is typical drawing which shows an example of the light-diffusion layer structure in this invention. It is typical drawing which shows an example of the light-diffusion member structure for illumination in this invention. It is drawing which shows the relationship between the transmittance | permeability in this invention, and a half value angle. It is drawing which shows the relationship between the transmittance | permeability in this invention, and a half value angle. It is drawing which shows the relationship between the transmittance | permeability in this invention, and a half value angle. It is drawing which shows the relationship between the filling rate of the light-diffusion material in this invention, and the transmittance | permeability. It is drawing which shows the relationship between d1 / d50 and the transmittance | permeability of the light-diffusion material in this invention. It is typical drawing which shows an example of the illuminating device using the light-diffusion member for illumination in this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  Components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted.

FIG. 2 shows a general structure of the light diffusing member 1. The light diffusing member 1 has a structure in which a light diffusing material 3 is dispersed in a transparent resin 2. Incident light (intensity I ₁ ) is emitted to the outside of the light diffusing member 1 while being diffused by the light diffusing member 3 when passing through the light diffusing member 1 (emitted light: intensity I ₂ ). Even if the incident light is a point light source emission such as a white LED module, light emitted to the outside of the light diffusing member 1 due to the light scattering effect of the light diffusing member 3 is in the horizontal plane direction of the light diffusing member 1. Since the light intensity is made uniform, glare can be reduced. At this time, there is a light scattering loss, and I ₂ / I ₁ is defined as the transmittance.

  In addition, the light-diffusion member 1 defined by this invention is a member for diffusing the light from an LED module, and points out what is also called a shade or a light-diffusion cover.

Next, the half-value angle used as an index of the degree of light diffusion will be described with reference to FIG. Light is incident on the light diffusing member 1 from a direction perpendicular thereto. The intensity of the emitted light is measured on the side opposite to the direction in which the light is incident as viewed from the light diffusing member 1 with θ being the angle from the direction perpendicular to the light diffusing member. The light intensity at an angle theta I _theta, the light intensity at the theta = 0 ° upon the I _0, define diffusion of light angles to be I θ ₌ 0.5I ₀ value angle and (theta _0.5) It is an index of sex.

  FIG. 4 shows the relationship between the transmittance and the half-value angle in a general light diffusing member. It can be seen that the transmittance and the half-value angle are in a trade-off relationship. That is, by increasing the half-value angle, the uniformity of light is improved, but the transmittance as it is lowered, so that the brightness as a lighting device is lowered. In the present invention, both transmittance and half-value angle are realized.

  One of the features of the present invention is that the volume concentration (filling rate) of the light diffusion material in the light diffusion layer is 5% or more and less than 74%. The filling rate of the conventional light diffusing member is less than 5%. In this case, as shown in FIG. 5, since the light scattering material concentration is dilute, It is necessary to increase the thickness. Therefore, the loss due to the long light transmission distance increases. On the other hand, the thickness of the light diffusion layer can be reduced by the filling rate of the present invention (FIG. 6), and the loss can be reduced because the diffusion distance of incident light is reduced. When the filling rate is 74% or more, so-called close-packing is achieved, and a part of the light diffusing material is exposed on the surface of the light diffusing layer, and the flatness of the surface of the light diffusing layer is impaired. Light extraction is impeded and performance is degraded.

  One of the features of the present invention is that the thickness (d1) of the light diffusion layer satisfies the relationship of 2.0 × d50 ≦ d1 ≦ 3.0 × d50 with respect to the median diameter (d50) of the light diffusion material. That is. With this configuration, the transmittance of the light diffusing material is improved.

  Another feature of the present invention is that the light diffusing member includes a light transmitting layer and a light diffusing layer. A method for producing the light diffusing member of the present invention will be described.

  FIG. 7 shows an example in which the light diffusing member 1 is composed of only the light diffusing layer 4. The light diffusion layer 4 was prepared by mixing the light diffusion material 3 with the transparent resin 2.

  As the transparent resin 2, an acrylic resin, a styrene resin, an acrylonitrile-styrene resin, a polycarbonate resin, a vinyl chloride resin, a polystyrene resin, a silicone resin, or the like can be used. As the light diffusing material 3, it is possible to use inorganic fine particles such as silica, calcium carbonate, barium sulfate, and fine particles such as acrylic resin and polystyrene resin. When silicone resin is used, there is a merit of high reliability with respect to heat and temperature.

  When a thermoplastic material is used as the transparent resin 2, the light diffusion layer is obtained by mixing and extruding the transparent resin 2 and the light diffusing material 3 while heating at about 250 to 350 ° C. using a screw extruder or the like. 4 can be molded. The thickness is preferably 200 μm or less.

  FIG. 8 shows an example in which the light diffusing member 1 is composed of a light diffusing layer 4 and a light transmitting layer 5. The light diffusing member 1 can be manufactured by heating and bonding the light diffusing layer 4 and the light transmitting layer 5 together. For production, a co-extruder or the like can also be used.

  As the transparent resin 6, an acrylic resin, a styrene resin, an acrylonitrile-styrene resin, a polycarbonate resin, a vinyl chloride resin, or a polystyrene resin can be used, and the light transmission layer 5 can be produced by the same method as the transparent resin 2. it can. The thickness is preferably 500 μm or more.

  When a thermosetting resin is used as the transparent resin 2, a mixture of the transparent resin 2 and the light diffusing material 3 is prepared, and then a film is formed on the surface of the light transmission layer 4 by a method such as screen printing, followed by heat curing. The light diffusing member shown in FIG. At this time, the thickness of the light diffusion layer is preferably 10 to 100 μm, and the thickness of the light transmission layer is preferably 500 μm or more.

  When the thermosetting resin is used, the thermosetting temperature is generally about 150 ° C., and the process temperature is lower than that when the above-described thermoplastic resin is used (thermosetting temperature: about 260 ° C.). Deformation due to thermal damage can be suppressed. Therefore, when the spherical light diffusing material 3 is used, the spherical shape can be maintained even after the light diffusing layer 4 is formed, and deterioration of the light scattering property can be suppressed.

In the transparent resin 6 (refractive index n1) that forms the light transmission layer 5, the transparent resin 2 (refractive index n2) that forms the light diffusion layer 4, and the light diffusion material 3 (refractive index n3) that forms the light diffusion layer 4 Is
By satisfying n1 ≧ n2 and n3> n2, light transmission loss can be reduced.

  The illuminating light diffusing member 1 of the present invention can be used only in the light diffusing layer, and further comprises a transparent layer for preventing contamination on the light emitting side surface of the light diffusing layer / light transmitting layer structure. Is also possible.

  These light diffusing members 1 can be molded into a desired shape by a method such as injection molding or pressure molding as required.

  Next, an example corresponding to this embodiment will be described.

(Comparative Example 1)
The structure of the light diffusing member 1 shown in FIG. 7 was produced by the following method.

Polymethylmethacrylate resin (refractive index 1.49) was used as the transparent resin 2, and polystyrene fine particles (refractive index 1.59) were used as the light diffusing material 3. The light diffusion layer 4 is mixed so that the volume concentration (filling rate) of the light diffusion material 3 is 1 vol%, and the transparent resin 2 and the light diffusion material 3 are heated and mixed and molded using a screw type extruder. A sheet having a thickness of 500 to 1000 μm was produced. The transmittance and half-value angle were measured using a commercially available haze meter and goniophotometer, and used as a reference for the following examples.
Example 1
In Example 1, the same structure of the light diffusing member 1 of FIG. 7 as that of Comparative Example 1 was produced by the following method. The difference from the first embodiment is the volume concentration of the light diffusing material 3.

  Polymethylmethacrylate resin (refractive index 1.49) was used as the transparent resin 2, and polystyrene fine particles (refractive index 1.59) were used as the light diffusing material 3. The volume concentration (filling ratio) of the light diffusing material 3 in the light diffusing layer 4 is adjusted to 5 to 73 vol%, and the transparent resin 2 and the light diffusing material 3 are heated and mixed and molded using a screw type extruder. Then, a sheet having a thickness of 200 to 300 μm was prepared, and transmittance-half-value angle characteristics were measured.

The results are shown in FIG. Compared to Comparative Example 1, an improvement in transmittance of about 3% was achieved at the same half-value angle.
(Example 2)
Example 2 is an example in which the light diffusion member 1 has a light diffusion layer / light transmission layer laminated structure.

  By using a coextrusion machine, the light diffusion layer / light transmission layer laminated structure of FIG. 8 was produced. The transparent resin 6 of the light transmission layer 5 is a polycarbonate resin having a thickness of 500 μm (refractive index: 1.59), and the light diffusion layer 4 has the same structure as the light diffusion layer 4 of Example 1. The transmittance-half-value angle characteristic of this structure was measured.

The results are shown in FIG. Compared with Comparative Example 1, a transmittance improvement of about 5% was realized at the same half-value angle. Further, the transmittance was improved with respect to Example 1. It is considered that the light transmission loss is reduced because the refractive index of the light transmitting layer ≧ the refractive index of the light diffusing layer> the refractive index of the air layer in the order in which the light travels.
Example 3
Example 3 is also an example in which the light diffusion member 1 has a light diffusion layer / light transmission layer laminated structure. The difference from Example 2 is the types of transparent resin 2 and transparent resin 6.

  As the transparent resin 6 of the light transmission layer 5, a polymethyl methacrylate resin (refractive index: 1.49) having a thickness of 500 μm was used. A light diffusing layer 4 was prepared using a silicone resin (refractive index 1.41) as the transparent resin 2 and a polystyrene resin (refractive index 1.59) as the light diffusing material 3. The volume concentration (filling rate) of the light diffusing material 3 in the light diffusing layer 4 was set to 5% or more and 73%. A sheet having a thickness of 10 to 100 μm was prepared, and transmittance-half-value angle characteristics were measured.

The results are shown in FIG. Compared with Comparative Example 1, the transmittance was improved at the same half-value angle.
Example 4
Example 4 is also an example in which the light diffusion member 1 has a light diffusion layer / light transmission layer laminated structure. The transparent resin 2, the light diffusing material 3, and the transparent resin 6 are all different from the second embodiment. What is different from the third embodiment is the type of the light diffusing material 3.

  As the transparent resin 6 of the light transmission layer 5, a polymethyl methacrylate resin (refractive index: 1.49) having a thickness of 500 μm was used. A light diffusion layer was prepared using a silicone resin (refractive index 1.41) as the transparent resin 2 and polymethylmethacrylate resin fine particles (refractive index 1.49) as the light diffusing material 3. The volume concentration (filling rate) of the light diffusing material in the light diffusing layer was set to 5% to 74%. A sheet having a thickness of 10 to 100 μm was prepared, and transmittance-half-value angle characteristics were measured.

  The results are shown in FIG. Compared with Comparative Example 1, a transmittance improvement of about 5% was realized at the same half-value angle.

  FIG. 12 is a plot of the transmittance with respect to the volume concentration (filling rate) of the light diffusing material 3 in the light diffusing layer 4, and this example versus the filling rate (1 vol%) in Comparative Example 1. The transmittance can be improved at a filling rate of 5% or more and less than 74%. If it is 74% or more, it becomes the so-called close-packed density or more, and part of the light diffusing material 3 (light diffusing particles) is exposed from the light diffusing layer 4, and the surface of the light diffusing layer 4 becomes uneven, so that transmission is possible. The rate is expected to decrease.

FIG. 13 shows an example of the ratio (d1 / d50) of the thickness d1 of the light diffusing layer to the median diameter d50 of the light diffusing material 3 used, and 2.0 ≦ d1 / d50 ≦ 3. The above range is preferable because the transmittance is particularly improved at 0.0. The median diameter (d50) can be measured with a laser diffraction particle size distribution meter. From here, the configuration and characteristics of a ceiling light using the light diffusing member 1 of Comparative Example 1 and Example 1-4 will be described. .
(Comparative Example 2)
Using the sheet of the light diffusing member 1 shown in Comparative Example 1, a dome-shaped shade was produced by pressure forming. The shade 9 was placed on the ceiling light lower substrate 7 to produce the ceiling light of FIG. The total luminous flux when the LED module 8 was turned on was measured and used as the standard value of the total light velocity of the ceiling light.
(Example 5)
Using the sheet of the light diffusing member 1 shown in Example 1, a dome-shaped shade was produced by pressure forming. The shade 9 was placed on the ceiling light lower substrate 7 to produce the ceiling light of FIG. Measure the total luminous flux when the white LED module 8 is turned on. The total luminous flux of this ceiling light was improved by about 3% compared to the standard value in Comparative Example 2.
Example 6
A dome-shaped shade was produced by pressure molding using the sheet made of the light diffusion member 1 having the light diffusion layer / light transmission layer laminated structure shown in Example 2. The shade 9 was placed on the ceiling light lower substrate 7 to produce the ceiling light of FIG. The light transmission layer 5 made of the transparent resin layer 6 is disposed on the side close to the white LED module 8, the light diffusion layer 4 is disposed on the side far from the white LED module 8, and the total luminous flux when the LED module 8 is lit is measured. did. The total luminous flux of this ceiling light was improved by about 5% compared to the standard value in Comparative Example 2.
(Example 7)
A dome-shaped shade was produced by pressure molding using the sheet made of the light diffusing member 1 having a light diffusing layer / light transmissive layer laminated structure shown in Example 3. The shade 9 was placed on the ceiling light lower substrate 7 to produce the ceiling light of FIG. The light transmission layer 5 made of the transparent resin layer 6 is disposed on the side close to the white LED module 8, the light diffusion layer 4 is disposed on the side far from the white LED module 8, and the total luminous flux when the LED module 8 is lit is measured. did. The total luminous flux of this ceiling light was improved by about 3% compared to the standard value in Comparative Example 2.
(Example 8)
A dome-shaped shade was produced by pressure molding using the sheet made of the light diffusing member 1 having a light diffusing layer / light transmitting layer laminated structure shown in Example 4. The shade 9 was placed on the ceiling light lower substrate 7 to produce the ceiling light of FIG. The light transmission layer 5 made of the transparent resin layer 6 is disposed on the side close to the white LED module 8, the light diffusion layer 4 is disposed on the side far from the white LED module 8, and the total luminous flux when the LED module 8 is lit is measured. did. The total luminous flux of this ceiling light was improved by about 5% compared to the standard value in Comparative Example 2.

  In the above embodiment, it is possible to further dispose a transparent layer on the surface of the light diffusion layer as necessary to prevent contamination.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiments and examples. However, the present invention is not limited to the above-described embodiments and examples, and does not depart from the spirit of the invention. It goes without saying that various changes can be made.

  The light diffusing member for LED illumination of the present invention can be widely applied for various illuminations such as a ceiling light, a straight tube illumination, a base light, and a light bulb illumination.

DESCRIPTION OF SYMBOLS 1 Light diffusing member 2 Transparent resin 3 Light diffusing material 4 Light diffusing layer 5 Light transmitting layer 6 Transparent resin 7 Ceiling light lower substrate 8 LED module 9 SEED

Claims (9)

It has a light diffusion layer composed of a transparent resin and a light diffusion material,
The light diffusion member for LED illumination, wherein the volume concentration of the light diffusion material in the entire light diffusion layer is 5% or more and less than 74%. The light diffusing member for LED illumination according to claim 1,
Furthermore, it has a light transmission layer composed of transparent resin,
The light diffusion member for LED illumination in which the light diffusion layer and the light transmission layer form a laminated structure. The light diffusing member for LED illumination according to claim 2,
The light diffusing member for LED illumination, wherein the refractive index (n1) of the transparent resin in the light transmission layer and the refractive index (n2) of the transparent resin in the light diffusion layer are in a relationship of n1 ≧ n2. The light diffusing member for LED illumination according to claim 3,
The light diffusing member for LED illumination, wherein the refractive index (n2) of the transparent resin in the light diffusing layer and the refractive index (n3) of the light diffusing material forming the light diffusing layer have a relationship of n3> n2. . In the light diffusion member for LED illumination in any one of Claims 1 thru | or 4,
The light diffusing member for LED illumination, wherein the thickness (d1) of the light diffusing layer satisfies the condition of 2.0 × d50 ≦ d1 ≦ 3.0 × d50 with respect to the median diameter (d50) of the light diffusing material . In the light diffusion member for LED illumination in any one of Claims 1 thru | or 5,
The light diffusing member for LED illumination, wherein the transparent resin constituting the light diffusing layer is a thermosetting resin. In the light diffusion member for LED illumination in any one of Claims 1 thru | or 5,
The light diffusing member for LED illumination, wherein the transparent resin constituting the light diffusing layer is a silicone resin. The light diffusing member for LED illumination according to claim 1;
A substrate,
An LED lighting device comprising: an LED module provided on the substrate. The light diffusing member for LED illumination according to claim 2;
A substrate,
An LED module provided on the substrate,
An LED illumination device comprising: a light transmission layer of the LED illumination light diffusion member provided on a side closer to the LED module; and a light diffusion layer of the LED illumination light diffusion member provided on a side far from the LED module. .