JP2011171104A - Light diffusion cover and lighting fixture using the light diffusion cover - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light diffusion cover that diffuses, transmits or reflects light emitted from an LED light source as a point light source to all directions in three dimensions without attenuating the light, using only one material without light guide plate, so that the light is emitted in a direction perpendicular to a light-emission direction and 360-degree directions without glare, and to provide a lighting fixture using the LED as a point light source. <P>SOLUTION: The light diffusion cover for a lighting fixture that uses an LED as a light source, is formed by using a PTFE porous film at a diffusion part of light emitted from the light source. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a light diffusing cover used in a lighting apparatus using a light emitting diode (hereinafter referred to as “LED”) as a light source, and particularly uses a porous film of polytetrafluoroethylene (hereinafter referred to as “PTFE”). And a lighting fixture using the light diffusion cover.

  In recent years, LEDs tend to be used as light sources for various illuminations due to the many advantages of LEDs, and various developments have been made. Even if the luminous efficiency of an LED is superior to that of an incandescent bulb, the use of one LED is limited because it is only a few watts even at high power. In other words, when illuminating in all directions, it can be applied to a lighting device such as a light source such as a nightlight that functions even when the luminous flux is low or a signal that is narrowed by making use of its straightness rather than widening the directivity angle of the LED and a flashlight. Widely used.

  However, a light fixture that illuminates the entire space brightly like a general room light lacks luminous flux, and the brightness and irradiation range are not comparable to incandescent bulbs and light bulb type fluorescent lamps. In addition, a tube with the same shape and the same cap as a straight tube fluorescent lamp has been developed. Of course, it is necessary to use a plurality of (in some cases, 100 or more) LEDs because a single LED cannot provide a sufficient luminous flux. Yes (Patent Document 1).

  Further, since the LED is a point light source, it is dazzling and glaring, and is non-uniform light emission. Therefore, as shown in FIGS. 10 and 11, it is not appropriate to use it for illumination as it is.

  As a solution for that, for example, a light guide plate, a diffusion plate, and a transmission plate are used for uniform LED surface-emitting illumination, and some of the problems have been solved. A separate material such as a transmission plate is required. Further, since the LED light source emits light at right angles from a flat element, the light has a drawback in the directivity. Therefore, a device has been devised in which a lens is disposed in the light source so that the light emission directivity angle is a wide angle of 120 degrees. For example, a bullet-type LED lamp product (Toricon Co., Ltd.) is commercially available, but the coherent light source remains unchanged. For example, it is dangerous that a portable light composed of an LED light source is directly incident on the human eye even with a small wattage. If an LED light source is used for an automobile lamp, it is too dazzling, and there is a risk of erroneous driving of an opposing car or bicycle. Further, in the fluorescent lamp type LED lighting apparatus, a large number of LED light sources are arranged and irradiated in the longitudinal direction of the tube, but the luminous flux for each LED light source can be seen and glare is a problem.

  Therefore, as a light diffusion cover that has been developed to prevent such obstacles, Patent Document 2 shows a lighting fixture that includes a light-transmitting cover that surrounds the entirety of a plurality of LED structures. The light-transmitting cover gives the impression that light is emitted from the entire lighting fixture and does not give the impression that light is emitted only from the LED. The light-transmitting cover may be a transparent body that transmits substantially all or part of the light incident from the LED structure, and a specific wavelength of a part of the incident light is difficult to transmit. It may be a transparent colored body as described above, or may be a polished glass shape or a frosted glass shape in which at least part of incident light is scattered. That is, there is no particular limitation on the transmittance, color tone, haze, etc. of the light-transmitting cover, but at least a part of the light incident from the LED structure is scattered and goes out to the outside. It is preferable for the reason that it gives an impression that light is emitted from the entire lighting fixture and is not dazzled by the LED structure even when the lighting fixture is directly viewed. It is particularly preferable for the above reason that the light-transmitting cover is clouded to such an extent that the contours of the individual LED structures enclosed inside cannot be visually identified. The light-transmitting cover has a tubular shape, and preferably has a light refracting body having a cylindrical lens effect in the longitudinal direction of the front surface of a plurality of LED structures arranged side by side. The photorefractive body is provided in order to obtain an effect that the illuminance does not decrease even when the distance from the LED or the luminaire is long, and the illuminance does not decrease even when the LED is angularly deviated from the irradiation direction. A light transmitting body is also provided to obtain this effect, but this effect is promoted by providing a light refracting body in the light transmitting cover. The shape of the photorefractive body needs to swell toward the center line in order to have the effect of a convex lens. The lower surface of the photorefractive body (the surface on the LED side) is substantially flat and has a shape like a kamaboko lens as a whole, but the lower surface may be concave or convex. The photorefractive body only needs to have the effect of the above-described cylindrical lens, that is, the focal length may be different depending on the location of the photorefractive body, and there may be distortion or aberration. Therefore, it is not necessary to form a real image in one place. The material of the photorefractive material includes inorganic substances such as glass and quartz; vinyl resins such as (meth) acrylic resins, styrene resins and vinyl chloride resins; polyester resins; organic polymer compounds such as polycarbonate resins Any may be used, and it is selected in consideration of optical characteristics, strength, durability, cost, workability and the like. When the transparent cover is made of glass or in order to make it similar to a general-purpose fluorescent lamp, the photorefractive body is preferably glass.

JP 2007-122933 A JP 2009-199863 A

  However, the conventional light diffusion cover disclosed in Patent Document 2 attenuates light emitted from the LED. That is, when the conventional light diffusion cover is irradiated with LED light, a part of the light is transmitted through the cover and radiated outside the cover, a part is reflected by the cover and returned to the cover, and a part is a cover layer. Proceed inside. The reflected light is again applied to the cover and dispersed into the three lights. Light traveling in the cover layer will be emitted outside or within the cover as it travels in the layer, but does not travel long in the direction of travel to attenuate while traveling in the layer, and therefore near the light source As a result, the cover emits light brightly, but becomes dark when it is away from the light source.

  The present invention does not require a light guide plate, diffuses and transmits light from an LED light source with a single material, and is free of light glare in a direction perpendicular to the light emitting direction and in a three-dimensional direction of 360 degrees. An illumination cover material that emits light, and that uses a light diffusion cover that diffuses, transmits, or reflects in three directions in three directions without attenuating LED emitted light that is a point light source, and an LED that is a point light source. It is to provide.

  The light diffusing cover according to the present invention is a light diffusing cover for a luminaire using a light emitting diode as a light source, and the light diffusing cover uses a porous film of polytetrafluoroethylene in a diffusion portion of light emitted from the light source. It is characterized by being made. With this configuration, the light diffusing cover according to the present invention uses a light source, in particular, a single film body irradiated with light from the LED, that is, a PTFE porous film body having reflection / diffusion / transmission performance as a cover material. In particular, in the illumination using LED as the light source, the PTFE porous film formed in a three-dimensional manner diffuses and reflects in the direction perpendicular to the traveling direction of the light emitted from the light source and three-dimensionally in all directions. A light diffusing cover that emits transmitted light. The light diffusing cover may have a transparent part in a part thereof. For example, the transparent part may be a part of the film body or may be impregnated with a transparent substance. Examples of the transparent substance include reactive resins that cause crosslinking such as organic liquids such as silicone oil and fluorine oil, such as epoxy and urethane. When configured in this manner, the light emitted from the LED emits three-dimensionally transmitted light in all directions by the diffusing portion and emits reflected light with higher illuminance from the transparent opening of the PTFE porous film, so that even brighter light is emitted. Can do. The light diffusion cover is preferably structurally reinforced with a rigid body such as a rigid sheet made of a transparent material on the inner surface, the outer surface, or both surfaces of the PTFE porous membrane. The PTFE porous membrane can be adhered and adhered to other materials due to the presence of a fine uneven surface. As an adhesive, there are a primer TB7797 and an adhesive TB7781 manufactured by Three Bond Co., Ltd., and these adhesives can be used to easily adhere the PTFE porous film to a metal surface, a glass surface or a resin surface. Moreover, you may use adhesive tapes, such as a double-sided tape. This PTFE porous membrane can be colored with a colored dye or a fluorescent dye dissolved in a solvent or the like, for example, with a magic ink (registered trademark of Hiroyuki Uchida). Therefore, it can also be set as the illumination cover material of various hues and patterns.

  As a porous film of PTFE used for the light diffusion cover, a molded body formed by firing or semi-firing a PTFE paste extrusion molding is created by expansion or stretching, and the surface roughness is 0.2 μm Ra to 0 μm. Specular gloss measured by gloss meter at 60 ° at 5 μm Ra is 30% or more, specific gravity is 0.9 to 1.3, thickness is 20 μm to 130 μm, air permeability Gurley number is 100 seconds / 100 CC to 10,000 seconds / It is preferred to use a porous membrane that is 100 CC. The thus configured PTFE porous film reflects and diffuses well the light emitted from the LED light source. Further, when the thickness is about 100 μm, light is transmitted well. The reason for selecting the properties of the PTFE porous membrane is as follows. A molded product fired or semi-fired at or above the melting point of PTFE obtained from PTFE paste molding reflects light well with a smooth surface, and transmits light well with a film body having a thickness of 100 μm or less. A comonomer-modified PTFE is more preferable in terms of light transmission. PTFE paste molding is a tube-like product in which a paste-like product obtained by adding about 20% by weight of a molding aid, for example, a solvent such as naphtha, to powder particles obtained by emulsion polymerization of PTFE is extruded into a tube or rod shape. The rod-shaped material is rolled into a film shape, and then the molding aid is removed by heating. Those that have only been removed are called unfired. A calcined product is formed by heat treatment at a temperature equal to or higher than the melting point of PTFE after drying and removal. Regarding the melting point of PTFE, the melting point of the polymer powder is around 340 degrees, and the melting point of the fired product is around 326 degrees. When the dried additive is heat-treated between the melting point of the polymerized powder of PTFE and the melting point of the baked product, a semi-baked product in which a part of the polymerized powder is melted is obtained. The porous film of the molded product is whitened by stretching or expansion processing. The reason for whitening is the irregular reflection of light due to the formation of complex irregularities in the light wavelength region size, that is, the diffusion of light, the repeated light irregular reflection due to the labyrinth hole formation continuous in the thickness direction, from the light source, It is thought that it is transmitted as whiter and incoherent light. The physical properties of the membrane can be determined by the permeation of fluid gas or compatible liquid, although the size of the continuous pore formation is maze-like, and the pore diameter can be determined. One method is known in which the maximum diameter is calculated from the initial pressure at which bubbles are generated by soaking in isopropyl alcohol and applying air pressure from one side. Further, there is a coulter porometer as a device that measures the amount of permeation from the initial point of pressure at which gas is permeated through fluorine oil until the flow rate increases and the flow rate disappears. The PTFE porous membrane applied to the present invention has an average pore diameter measured by these of 0.1 μm or less. The coulter porometer has a limit on the maximum value of the working pressure, and it is difficult to measure the minimum diameter. The pore-forming state of the porous PTFE membrane is a Gurley number that can be measured by a Gurley meter that measures the amount of air permeated (measured in accordance with JIS P 8117: 1998, the time for passing 100 CC of air) from 100 seconds to 10,000. Between seconds. The specific gravity of the PTFE porous membrane is 0.9 to 1.3, and the void ratio is about 50%. The reason is that when the specific gravity is 0.8 or less, the hole forming size is increased and the reflectance is lowered. When the specific gravity is 1.4 or more, there are few pores and diffusion is insufficient. The PTFE porous body of the present invention is different from the porous body obtained by stretching and expanding a PTFE paste molded product disclosed in JP-A-51-30277 in an unsintered state. In particular, the film body obtained in Japanese Patent Application Laid-Open No. 51-30277 is stretched and expanded while PTFE is in an unsintered state, so that the PTFE material is composed of particles of about 0.2 to 0.3 μm. The film body has a drawback that the reflectance of light decreases. The amount of transmitted light has a correlation with the thickness of the porous PTFE membrane, and the amount of light increases as the thickness decreases. When a light diffusion cover made of a PTFE porous material having such physical properties is irradiated with LED light, part of the light is transmitted through the cover and radiated to the outside of the cover, and part of the light is reflected by the cover and returned to the cover. In addition, some progress in the cover layer. The reflected light is again applied to the cover and dispersed into the three lights. Light traveling in the cover layer will be emitted outside or inside the cover while traveling in the layer, but will travel longer in the traveling direction because there is no light attenuation while traveling in the layer, and therefore near the light source This cover not only emits bright light, but also emits bright light even when it is away from the light source.

  Moreover, the lighting fixture which concerns on this invention uses the light-diffusion cover of the said structure, and uses LED as a light source, It is characterized by the above-mentioned. It can be set as a lighting fixture by using the lighting cover of this invention as components. When it is set as a lighting fixture, it can be enriched with a transparent material in the internal structure where light is reflected and diffused. For example, it can be composed of glass or polycarbonate. The illuminance of the object to be irradiated by the illumination cover of the present invention is sufficient if it can be identified by a CMOS image sensor mounted on a mobile phone or the like.

  In the lighting apparatus, the light diffusion cover is composed of a hollow cylindrical body whose both ends are closed, and a light source is arranged at one or both ends of the cylindrical body so as to emit light toward the cylindrical body. Also good. The PTFE porous membrane is preferably in the shape of a lighting cover material having a cylindrical shape. The shape of the cover material is a three-dimensional configuration of a PTFE porous film, for example, a cylindrical or dome shape, and when an LED light source is placed at one end, the light emitted from that end is reflected and diffused, and the incident angle is perpendicular to the surface. As a result, light can be emitted three-dimensionally and three-dimensionally through the PTFE porous membrane. The cylindrical PTFE porous body can be produced by the method described in Japanese Patent Publication No. 5-33650. Among these methods, a porous article having a specific gravity of 0.9 to 1.2 is preferably selected. The physical properties of these articles are disclosed in JP-A-9-185282 (tubular film). The thickness is preferably in the range of 25 μm to 130 μm. Furthermore, in the said lighting fixture, it is good also as a structure where the light-diffusion cover has comprised the cone shape or the dome shape. By making the PTFE porous membrane conical or dome-shaped, diffusion can be enhanced and brighter. The means for forming the cylindrical shape, the conical shape, the dome shape, or the semi-cylindrical shape is not limited to a manufacturing method made from a cylindrical molded product, and may be formed from a flat film shape. The dome-shaped porous PTFE can be obtained by heating and expanding an unstretchable PTFE material into an arbitrary dome shape. For example, it can be formed into a dome shape by sandwiching a PTFE semi-fired film with a sheet of polyethylene terephthalate, heating it above the melting point (about 260 ° C.) of the polyethylene terephthalate, and then performing expansion molding in a mold. The PTFE semi-fired film is obtained by heat-treating a film obtained by PTFE paste extrusion and rolling between the melting point of unsintered PTFE and the melting point of sintered PTFE. This is known from Japanese Patent Laid-Open No. 58-145735.

  Moreover, it is good also as a structure which distribute | arranged the reflecting mirror to the other edge part of the said cylindrical body, and has distribute | arranged so that the mirror surface of the said reflecting mirror may face the light source of one edge part. When the porous film is cylindrical, the LED light source is disposed at one end, and the reflection mirror is disposed at the other end, whereby the amount of emitted light can be increased and the brightness can be further increased. In addition, the brightness can be increased by using a plurality of LED light sources arranged at one end. Furthermore, a light source can be arrange | positioned at both ends and a cylindrical part can also be lengthened.

  According to the present invention, the light from the LED light source can be emitted in the direction of light emission by using a PTFE porous film having the performance of reflection, diffusion, and transmission without using a light guide plate and having a single material for diffusion and transmission. It is possible to provide a lighting cover material that emits light without glare in a three-dimensional direction of 360 degrees in the vertical direction. As a result, the amount of light from the LED light source can be effectively utilized, and energy efficient lighting can be achieved, so that energy saving can be promoted. The cost of the cover material can be reduced, the weight can be reduced, and the flame resistance can be reduced, and the light fixture can be reduced in weight and carried. Furthermore, since the cover material has the most heat resistance among the plastics and is flame retardant, the lighting can be maintained during evacuation in the event of a fire. Since it does not deteriorate at all over the entire region from the ultraviolet region to the infrared region, and has excellent resistance to substances in all living environments such as water and oil, it can be used in severe environments. Moreover, this invention becomes the illumination cover material of the carrying light which uses an LED light source, the light in a bathtub, a mark, and the lighting fixture for a label | marker. For example, it is a landmark or sign that can be seen from any direction even in darkness. Furthermore, if it is made into the illumination cover material of a portable light, it can be set as the lighting fixture which can look over the whole range in the tent at night. Characters and designs can be freely depicted with a colorant on the cover material. It can be used as an emergency lighting device or a blame guide lighting device in the event of a power outage in the event of a disaster. As described above, the present invention exhibits various excellent effects in daily life.

It is a photograph of the LED light lighting fixture used as a light source. 6 is a schematic diagram showing the spread of light brightness in Comparative Example 1. FIG. In the measurement experiment of the comparative example 1, it is the photograph which darkened the circumference | surroundings and turned on, and showed the breadth of the light on the section sheet. 2 is a photograph of a measurement material in Example 1. It is a photograph which shows the state which attached the measurement material in Example 1 to the front-end | tip of LED light. It is the photograph which attached the measuring material in Example 1 to the front-end | tip of LED light, darkened the circumference | surroundings, turned on, and represented the breadth of the light on a section sheet. FIG. 3 is a schematic diagram showing the spread of light brightness in Example 1. 3 is a photograph of a measurement material in Example 2. 12 is a modification example of the light diffusion cover in the third embodiment. It is a photograph which shows the spreading state of the light of the conventional fluorescent lamp type LED lighting fixture. It is a schematic diagram which shows the spreading state of the light of the conventional fluorescent lamp type LED lighting fixture.

  Examples of the present invention will be described below, but the present invention is not limited thereto.

  As Comparative Example 1, the following light source and illuminance meter were used, and the brightness spread from the light source of the LED light and the illuminance were measured.

  As the LED light used as the light source, “ELPA 0.5W LEDLIGHT DOP-10SL (manufactured by Asahi Denki Co., Ltd.)” shown in FIG. 1 was used. FIG. 1 is a photograph of an LED light luminaire used as a light source. The illuminometer is “TM-204 (manufactured by Taiwan TENMARS ELECTRONICS CO., LTD.)”.

  Next, a measurement method using an illuminometer will be described. First, the measurement point and measurement direction of illuminance by an illuminometer were determined as follows. The measurement direction in which the center line of light emission in the light source is the optical axis, and the direction parallel to the optical axis is the light receiving direction of the illuminometer is referred to as the opposite measurement direction, and is opposed at a position 100 mm from the light source in the optical axis direction. The measurement direction was defined as measurement point A, and the opposite measurement direction at a position of 200 mm was defined as measurement point D. The opposing measurement directions at positions 50 mm away from the positions A and D of the two measurement points in the direction perpendicular to the optical axis were defined as measurement points B and E. Further, the opposing measurement directions at positions 100 mm away from the two positions A and D in the direction perpendicular to the optical axis were defined as measurement points C and F. The measurement direction in which the direction perpendicular to the optical axis with respect to the light source is the light receiving direction of the illuminometer is referred to as the vertical measurement direction, and the vertical direction at a position 50 mm away from the light source in the vertical direction of the optical axis at the position of 100 mm in the optical axis direction. The measurement direction was defined as measurement point L, and the vertical measurement direction at a position 100 mm apart was defined as measurement point H. The vertical measurement direction at a position 50 mm away from the light source in the optical axis direction at a position of 200 mm in the vertical direction of the optical axis was defined as a measurement point M, and the vertical measurement direction at a position 100 mm away from the light source.

  FIG. 2 is a schematic diagram showing the spread of brightness in Comparative Example 1. In FIG. 2, the measurement points A to F, L, H, M, and N are shown. FIG. 3 is a photograph showing the spread of the brightness of light expressed on the section sheet by darkening the periphery in the measurement experiment.

The measurement results are shown in Table 1 below. Table 1 shows the illuminance at each measurement point when the LED light illuminator is irradiated without using the light diffusion cover. As shown in Table 1, the illuminance of the light source on the optical axis is approximately halved at 100 mm and 200 mm from the light source. However, at a position away from the optical axis in the vertical direction, the illuminance with respect to the light source measured in the direction parallel to the optical axis, that is, in the opposite measurement direction, extremely decreases as the distance from the optical axis increases. In addition, the illuminance with respect to the light source measured in the direction perpendicular to the optical axis, that is, in the vertical measurement direction was considerably low. From this, the illumination of the light in Comparative Example 1 has a lighting effect in the optical axis direction of the light, but the illuminance is extremely lowered at a position away from the optical axis, and it serves as a lighting fixture that illuminates the entire surroundings. It can be seen that it cannot be fulfilled.

As Comparative Example 2, the three-dimensional spread of illuminance by the PTFE porous membrane was considered. That is, the light emitting surface of the light was covered with a cover material, and the illuminance in the opposite direction when the light was turned on was measured. The cover material, which is a measurement material, is a PTFE porous film processed and manufactured by the method described in Japanese Patent Publication No. 5-33650, and its properties are measured by a gloss meter with a surface roughness of 0.2 μmRa and 60 degrees. The specular gloss is 40% gloss and the porosity is 45%. The measurement results are shown in Table 2. Table 2 shows the illuminance in the opposite measurement direction when the cover material is a flat film and attached to the front. As a result, when the cover material is installed as a flat film at a position facing the axis of the emitted light, a large distribution of illuminance appears and there is a defect that causes glare of the light source.

In Example 1, a tube formed of a PTFE porous film in a cylindrical shape was used as a light diffusion cover material attached to the tip of the LED light, and the same measurement as in Comparative Example 1 was performed. That is, as the LED light used as the light source, “ELPA 0.5 W LEDLIGHT DOP-10SL (manufactured by Asahi Electric Co., Ltd.)” shown in FIG. 1 was used. The illuminometer is “TM-204 (manufactured by Taiwan TENMARS ELECTRONICS CO., LTD.)”. A tube made of PTFE porous membrane as a measurement material is formed from a PTFE porous membrane processed and manufactured by the method described in Japanese Patent Publication No. 5-33650, and the property of the PTFE porous membrane is surface roughness. Has a gloss of 40% and a porosity of 45%. A tube having an inner diameter of 37 mm and a wall thickness of 100 μm was formed from this PTFE porous membrane to obtain a measurement material. In addition, in order to maintain the shape of the tube, the inner and outer surfaces of the tube were reinforced with a film of polyethylene terephthalate having a thickness of 50 μm as a measurement material. This measurement material was attached to the tip of the LED light, and the LED light was turned on. FIG. 4 is a photograph of the measurement material, FIG. 5 is a photograph showing the attachment state, FIG. 6 is a photograph showing the lighting state, and FIG. 7 is a schematic diagram showing the spread of light brightness. Table 3 shows the illuminance at each measurement point.

  When the measurement material in Example 1 is used, as shown in Table 3, the result is that the illuminance is further increased in a three-dimensional, multifaceted and perpendicular direction to the axial direction of the light. It was.

Example 2 is a measurement material reinforced with polyethylene terephthalate in the same manner as in Example 1 except that a slit part (transparent part) in which a part of the tube in Example 1 is cut and opened by about 20 mm in width and 160 mm in length is provided. The measurement was performed in the same manner as in Example 1. FIG. 8 is a photograph of the measurement material. Table 4 shows the illuminance at each measurement point.

  When the measurement material in Example 2 was used, as shown in Table 4, a result in which the illuminance increased more from the slit portion than the measurement result in Example 1 was obtained.

[Discussion]
Based on the measurement results of Comparative Examples 1 and 2 and Examples 1 and 2, the three-dimensional spread of illuminance by the PTFE porous material was considered. Table 5 is a list of the measurement results. The illuminance in the opposite measurement direction was measured when the PTFE porous body was turned into a flat film on the front of the light. When the cover material is installed in a position facing the axis of the emitted light in a flat film, a large distribution of illuminance appears and there is a defect that causes glare of the light source. Comparing the illuminance in the vertical measurement direction when the cover material according to the embodiment of the present invention is installed, the emitted light reflected / transmitted from the cover material 1 spreads in three dimensions and the illuminance distribution is averaged. It can be seen that

  In addition, the illuminance at the measurement points L, H, M, and N in Comparative Example 1 is perpendicular to the optical axis at a point 100 mm in the optical axis direction when compared with the illuminance at the measurement points L, H, M, and N in Example 1. Although the illuminance at the measurement point L of 50 mm is not significantly different, the illuminance at the measurement point H of 100 mm in the vertical direction from the optical axis at the same point is considerably different. From this, Example 1 is more perpendicular to the optical axis. You can see that the light in the direction travels far. In addition, the difference in illuminance at the measurement point M in the vertical direction 50 mm from the optical axis at a point of 200 mm in the optical axis direction is large. From this, in Example 1, the light emitted from the light source is farther in the optical axis direction. It can be seen that the light from the optical axis is transmitted far away.

  From the above, it can be estimated that the light emitted from the light source proceeds without being attenuated in the layer of the PTFE porous membrane. Furthermore, since the illuminance at the measurement points L, H, M, and N in Example 2 is considerably larger than those in Comparative Example 1 and Example 1, light passing through or reflecting in the tube is attenuated to the transparent part. You can see that it is being transmitted.

As a result of the above consideration, if a PTFE porous film is used, the light of the LED is uniformly diffused in all directions, so that it is proved that it is excellent as a cover material for the light diffusion cover of LED illumination.

  The present embodiment is a modification of the cylindrical body, and is formed in a conical shape as shown in FIG. The PTFE porous membrane described in Example 1 was used as the material, and a polyethylene terephthalate film was laminated on the inner and outer surfaces to maintain the shape and maintain the strength.

A: Measurement point in the opposite measurement direction at a position 100 mm from the light source in the optical axis direction B: Measurement point in the opposite measurement direction at a position 50 mm away from the position of the measurement point A in the direction perpendicular to the optical axis C: From the position of the measurement point A Measurement point in the opposite measurement direction at a position 100 mm away in the vertical direction of the optical axis D: Measurement point in the opposite measurement direction at a position 200 mm in the optical axis direction from the light source E: 50 mm away from the position of the measurement point D in the vertical direction of the optical axis F: Measurement point in the opposite measurement direction at a position 100 mm away from the position of the measurement point D in the vertical direction of the optical axis L: Vertical direction of the optical axis at a position 100 mm from the light source in the optical axis direction Measurement point in the vertical measurement direction at a position 50 mm away from the light source H: At a position 100 mm away from the light source in the vertical direction of the optical axis at a position 100 mm in the optical axis direction Measurement point in the vertical measurement direction M: Measurement point in the vertical measurement direction at a position 50 mm away from the light source in the optical axis direction at a position 200 mm in the optical axis direction N: Vertical direction of the optical axis at a position 200 mm in the optical axis direction from the light source Measurement point in the vertical measurement direction at a position 100 mm away

Claims (5)

  A light diffusing cover for a luminaire using a light emitting diode as a light source, wherein the light diffusing cover is formed by using a porous film of polytetrafluoroethylene in a diffusion portion of light emitted from a light source. Diffusion cover.   A porous film is formed by expanding or stretching a molded body formed by firing or semi-firing a polytetrafluoroethylene paste extrudate, and the surface roughness of the porous film is 0.2 μmRa to 0.5 μmRa. , The specular gloss measured by a gloss meter at 60 degrees is 30% or more, the specific gravity is 0.9 to 1.3, the thickness is 20 μm to 130 μm, and the air permeability Gurley number is 100 seconds / 100 CC to 10,000 seconds / 100 CC. The light diffusion cover according to claim 1.   A light fixture comprising the light diffusing cover according to claim 1 and a light emitting diode as a light source.   4. The light diffusing cover is formed of a hollow cylindrical body whose both ends are closed, and a light source is disposed so that light is emitted toward one or both ends of the cylindrical body toward the cylindrical body. The lighting fixture as described in.   The lighting apparatus according to claim 4, wherein a reflector is disposed at the other end of the cylindrical body so that the mirror surface faces the light source at the one end.