JP5577209B2 - Lighting device - Google Patents

Description

  The present invention relates to a lighting device suitable for expanding a light distribution, for example, in a lighting device using a light emitting diode (LED) as a light source.

  In recent years, LED light sources that do not use harmful substances and have good luminous efficiency have been put to practical use as light sources used in lighting devices from the viewpoint of energy saving effects and environmental protection. In addition, LED light sources are expected to be widely used as light sources to replace fluorescent lamps and incandescent lamps because they have higher color rendering properties and longer life than conventional fluorescent lamps and incandescent lamps.

  An illumination device using an LED light source, for example, covers the periphery of the LED light source with a spherical translucent cover, converts the light from the LED light source into a light distribution close to a sphere like a conventional tungsten light bulb, and illuminates the illumination area. A light bulb type that irradiates the light source is known. Hereinafter, a bulb-type illumination device using this LED light source will be referred to as an “LED bulb”.

  The LED light source has a high light intensity in the optical axis direction and a high directivity. That is, the LED light source has a narrow light distribution compared to an incandescent bulb such as a tungsten bulb, and it is necessary to expand the light distribution to use an LED bulb using such an LED light source as an alternative to an incandescent bulb.

  As a prior art for extending the light distribution of the LED light source, for example, one described in Patent Document 1 is known. Patent Document 1 discloses a light distribution distribution of an LED bulb by covering the LED light source with an elliptical semi-transparent cover having a short diameter in the direction directly above the light from the LED light source and a long diameter in the direction perpendicular to the directly above direction. Expanding is disclosed.

JP 2009-295299 A

  By the way, it is assumed that lighting fixtures that are assumed to use light bulbs, such as stand lights with reflectors, are used with light bulbs having a wide light distribution that emit in the vicinity of the base of the light bulb. Designed.

  As described above, since an LED bulb has a narrow light distribution compared to a conventional incandescent bulb or the like, it is difficult to irradiate light over a wide range even when used in combination with a conventional lighting fixture for a bulb.

  Although the prior art described in Patent Document 1 discloses the widening of the light distribution of the LED bulb, the light distribution is extended to the direction of the mounting portion of the LED bulb, that is, the direction of the base of the LED bulb. Was not considered.

  This invention is made in view of the said subject, Comprising: In illuminating devices, such as an LED bulb using an LED light source, extending a light distribution to the direction of the attachment part (for example, nozzle | cap | die) of an illuminating device. It provides technology that can

  An illuminating device according to the present invention includes at least one LED light source and a cover member that covers the periphery of the light output portion of the LED light source and has translucency and light diffusibility. A cross-section in a plane including the central axis of the cover member has a long oval shape in a direction orthogonal to the central axis, and the maximum dimension of the cover member in the direction orthogonal to the central axis is the cover member, It is located in the said LED light source side rather than the center of the dimension of a center axis direction.

The cover member has a distance R from the light source to the point P on the cover member, an angle formed by a line segment connecting the rotational symmetry axis of the cover member and the light source and the point P on the cover member, θ, When the emission intensity in the θ direction is E (θ), when the cross-sectional shape on the plane including the central axis (rotation symmetry axis) of the cover member is a polar coordinate system and θ is 60 degrees or less, it is expressed by the following equation: Has a shape.

  Moreover, the illumination device according to the present invention includes at least one LED light source, a first cover member that covers the periphery of the light output portion of the LED light source, and has translucency and light diffusibility, and the first light source. A light-transmitting second cover member covering the periphery of the cover member, and the first cover member has a cross section in a plane including the central axis of the first cover member orthogonal to the central axis. It is characterized by a long oval shape in the direction.

  ADVANTAGE OF THE INVENTION According to this invention, in the illuminating device using an LED light source, it becomes possible to expand light distribution even to a nozzle | cap | die direction. Therefore, an illuminating device that can illuminate light in a wider range can be provided.

The figure which shows 1st Example of the illuminating device (LED light bulb) which concerns on this invention. The figure which shows the example of mounting on the light source board | substrate 2 of the light source 1. FIG. The figure which shows an example of the cross-sectional shape of the cover member 5 which concerns on 1st Example. The figure which shows an example of the light distribution of LED The figure which shows an example of the light distribution when the cover member 5 which concerns on 1st Example is used. The figure which shows 2nd Example of the illuminating device which concerns on this invention. The figure which shows 3rd Example of the illuminating device which concerns on this invention. The figure which shows 4th Example of the illuminating device which concerns on this invention. The figure which shows an example of arrangement | positioning of the light source which concerns on 5th Example, and the cross-sectional shape of the cover member 5. FIG.

  Embodiments according to the present invention will be described below with reference to the accompanying drawings. In the following description of the embodiments, parts having the same function and action are denoted by the same reference numerals, and redundant description is omitted.

  A first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view of an LED bulb that is a lighting device according to a first embodiment of the present invention.

  In FIG. 1, for example, a top-view LED that emits light in a direction orthogonal to the electrode surface is used as the light source 1, and is mounted on the light source substrate 2. FIG. 2 shows an example in which the LED as the light source 1 is mounted on the light source substrate 2. FIG. 2A shows an example in which one of the white LEDs that emit white light is mounted at substantially the center of the light source substrate 2, and FIG. 2B shows a plurality of white LEDs (four in the figure). 2 shows an example in which the light source substrate 2 is mounted in a two-dimensional array. In this example, a white LED that emits white light is used as the LED. However, for example, three LEDs that emit three primary colors of RGB may be used, and a plurality of sets of these three LEDs may be used. It may be mounted on the light source substrate 2. In this embodiment, an LED is used as the light source 1, but a laser light source such as a semiconductor laser may be used. Furthermore, as the LED light source 1, a light emitting part of the LED covered with a lens, for example, may be used, or a light emitting characteristic given by a mirror or glass may be used.

  The light source board 2 is a printed board formed of, for example, glass epoxy resin, and an LED driver (not shown) for supplying a PWM signal for turning on the LED in addition to the LED as the light source 1 to the LED. ), A control circuit (not shown) such as a microcomputer for controlling the duty of the PWM signal from the LED driver and adjusting the intensity and color of the light from the LED, and other resistors and capacitors Circuit parts such as these are mounted. The light source substrate 2 may be a double-sided substrate, and the LED driver, control circuit, circuit component, etc. may be mounted on the opposite surface on which the light source 1 is mounted.

  There is a possibility that the light source 1 generates heat due to the light emission and the temperature rises, and the light emission efficiency decreases due to the temperature characteristics of the light source 1. In order to reduce such a decrease in efficiency, the light source substrate 2 may be made of a material with good heat dissipation, for example, a metal or alloy having high heat transfer performance using copper, aluminum, or the like, or a structure provided with heat radiation fins It is good. Furthermore, when there is a possibility that light emitted from the light source 1 is reflected by the inner surface of a cover member described later and enters the light source substrate 2, an optical sheet is provided on the surface of the light source substrate 2 (surface on which the light source 1 is mounted). For example, a reflection member such as a diffuse reflection sheet or a mirror sheet that substantially reflects specularly may be provided to reflect light reflected by the inner surface of the cover member again, thereby improving the light utilization efficiency.

  The main body 3 has a cylindrical shape made of, for example, resin. The light source substrate 2 is mounted on one end (upper side of the paper), and on the other end (lower side of the paper), for example, indoors A base 4 is provided as an attachment portion on which a screw for attaching to a socket of a light bulb socket or a table lamp is formed. The main end 3 has a built-in converter that rectifies the commercial AC power supplied via the base 4 and converts it into a power supply voltage for supplying the LED driver and control circuit.

  Furthermore, a cover member 5 formed of, for example, a transparent resin having translucency is attached to one end of the main body 3 where the light source substrate 2 is mounted so as to cover the light output portion of the light source 1. Yes. For example, a screw or a hook is formed on the cover member 5, and is attached to the main body portion 3 by screwing or fitting. Further, an opening for inserting and attaching the light source 1 and the light source substrate 2 is provided in the vicinity of the light source 1 of the cover member 5.

  The cover member 5 will be described in more detail.

  The cover member 5 is made of a transparent member such as acrylic, PMMA (Polymethylmethacrylate), ZEONOR, BMC (bulk molding compound), OZ, polycarbonate, silicon, glass, and the like. The cover member 5 has a diffusivity (a diffusion function) for diffusing light from the light source 1. In order to impart such a diffusion function to the cover member 5, a blasting process for roughening the surface of the cover member 5 is performed. Instead of blasting, fine beads may be attached to the surface of the cover member 5 or may be sprayed. Or you may make it provide the said spreading | diffusion effect by mixing the fine particle from which refractive index differs into the material itself which forms the cover member 5. FIG.

  The cover member 5 has a rotationally symmetric shape with respect to the central axis A (illustrated by a dotted line extending in the vertical (vertical) direction in FIG. 1). That is, the center axis A of the cover member 5 is also a rotationally symmetric axis of the cover member 5. Here, it is assumed that the central axis A passes through the center of the light source substrate and the central axis of the cylindrical main body 3. As shown in FIG. 1, the cover member 5 has a horizontally long oval shape whose cross section on the plane including the central axis A is long in the direction orthogonal to the central axis (left and right (horizontal) direction on the paper surface). ing. Here, in this embodiment, the cross-sectional shape of the cover member 5 is not a mere oval or elliptical shape that is horizontally long in the direction orthogonal to the central axis A, but the portion having the largest dimension in the direction orthogonal to the central axis A, that is, The width W in FIG. 1 is the dimension of the cover member 5 in the central axis direction (vertical direction), that is, the center C of the height H in FIG. 1 (illustrated by the alternate long and short dash line in FIG. The shape is such that it is positioned closer to the light source 1 side (lower side of the paper).

  Accordingly, in this embodiment, light emitted from the light source 1 at a large angle with respect to the central axis A, for example, an angle of 60 degrees or more, in the portion near the light source 1 side of the cover member 5 is directed to the base 4 (downward on the paper surface) ) Can be greatly refracted and diffused, and the distribution of light distribution when viewed from the entire LED bulb can be expanded or expanded.

  Details of the shape of the cover member 5 according to the present embodiment will be described with reference to FIG.

As described above, the cover member 5 has a substantially rotationally symmetric shape with respect to the central axis A, and the central axis A (rotational symmetry axis) is assumed to be disposed at the center of the LED bulb here. As shown in FIG. 3, the cover member 5 is expressed by the following equation 1 when the shape of the cross section of the cover member 5 in a plane including the central axis A is a polar coordinate system and θ is 60 degrees or less. The shape is almost similar.

Here, R is the distance from the origin O to the point P on the cover member 5, and θ is the angle formed by the rotational symmetry axis and the line segment connecting the origin O and the point P on the cover member 5. . E (θ) in Equation 1 is a function representing the amount corresponding to the light emission intensity in the θ direction, and is the same as the function representing the light distribution of one LED, for example. Assuming that the light distribution of the LED is expressed by, for example, cos θ, an expression representing the cross-sectional shape of the cover member 5 is expressed by the following formula 2.

  Here, an example of the light distribution of the LED is shown in FIG. FIG. 4 shows a light distribution of a LED that emits Lambert light in a state where an element for adjusting the light output characteristic such as a lens is not added. It is the graph which plotted the position where light intensity becomes equal on the basis of the center of LED.

  As shown in FIG. 4, the intensity of the light emitted from the LED follows cos θ, and the optical intensity in the optical axis direction of the LED (direction perpendicular to the light emitting surface of the LED), that is, θ = 0 is maximum, The light intensity in the direction orthogonal to the optical axis of the LED, that is, when θ = 90 is zero. Thus, the LED has a high directivity and a narrow light distribution. In particular, almost no light is emitted to the back side of the light emitting surface of the LED (in the direction of the cap 4 in FIG. 1).

  On the other hand, incandescent bulbs such as tungsten bulbs that have been used in the past have a very low directivity because light from the filament is emitted in all directions, and have a wide light distribution that also emits light in the direction of the base. doing. Thus, in order to use an LED bulb using an LED as a light source as an alternative to an incandescent bulb such as a conventional tungsten bulb, it is necessary to obtain a light distribution that extends in the direction of the base.

  Therefore, in this embodiment, by forming the cross-sectional shape of the cover member 5 in accordance with the above formula 1 or 2, the light distribution that spreads in the direction of the die is obtained. In the present embodiment, the equation representing the cross-sectional shape of the cover member 5 is equal to or proportional to the square root of the function representing the light distribution of the LED as shown in Equation 2, for example, from the LED on the cover member 5. This is to make the intensity (energy) per unit area of light substantially equal. In other words, the cover member 5 having a shape according to the above formula 1 or formula 2 is an aggregate of points having the same intensity per unit area of the light emitted from the light source 1. In addition, when the light source 1 has a function of light distribution different from cos θ, the cross-sectional shape of the cover member 5 follows the square root of the function.

  In this embodiment, the light intensity per unit area at each position of the cover member 5 is made substantially equal so that the intensity of the light diffused by the cover member 5 is made substantially uniform at each position of the cover member 5. Can do. That is, light having substantially the same intensity as the light diffused at the point θ = 0 of the cover member 5 (portion intersecting the central axis A) can be obtained at the portion of the cover member 5 where θ> ± 60 °. As a result, it is possible to distribute light having a relatively strong intensity on the back side of the light source 1 (in the direction of the base 4). Furthermore, the shape of the cover member 5 according to the above formula 1 or 2 is such that the portion (width W in FIG. 1) having the largest dimension in the direction perpendicular to the axis A is the central axis of the cover member 5 as described above. It can be made into the shape which is located in the light source 1 side rather than the center C of the dimension (height H) of a direction. Accordingly, light emitted from the light source 1 at a large angle with respect to the central axis A, for example, an angle of 60 degrees or more, is refracted and diffused more greatly in the direction of the base 4 at a portion near the light source 1 side of the cover member 5. It is possible to expand or enlarge the light distribution when viewed from the whole LED bulb.

  FIG. 5 shows a simulation result of the light distribution when the light from the LED is diffused by the cover member 5 according to the present embodiment. As shown in FIG. 5, the light distribution is broadened by the cover member 5 according to the present embodiment, and also in the back direction (the range of 90 ° and −90 ° or more, that is, the direction of the base 4) in the light emitting direction of the light source 1. It can be confirmed that light is emitted.

  As described above, it has become clear from experiments or simulations by the present inventors that if θ is 60 degrees or less and Equation 1 is established, a wide light distribution that emits light in the direction of the base 4 of the LED bulb can be obtained. . Furthermore, if the number 1 and the cover member 5 are similar in the range of θ of 80 degrees or less, the amount of light directed toward the base can be further increased, and the light distribution of a conventional incandescent bulb is approached. In a region where θ is approximately 90 degrees, it may be configured as a substantially flat surface in consideration of manufacturing accuracy.

  As described above, according to the configuration of the present embodiment, since a wide light distribution like a conventional incandescent bulb can be obtained by using an LED light source, when the light source is attached to a lighting fixture for a conventional incandescent bulb. In addition, it is possible to illuminate light equivalent to a conventional incandescent bulb. Therefore, according to the present Example, the light distribution which the light source 1 has can be expanded, and the LED bulb which has the performance close | similar to the light distribution which a conventional incandescent lamp has, and an illuminating device can be provided. .

  A second embodiment of the lighting device according to the present invention will be described with reference to FIG. FIG. 6 is a cross-sectional view of a lighting apparatus according to the second embodiment of the present invention.

  In the second embodiment 2, the light source 1, the light source substrate 2, and the cover member 5 (in the second embodiment, the cover member 5 is referred to as “first cover member 5”) in addition to the configuration of the first embodiment. And a second cover member 6 having translucency and diffusibility is provided.

  In FIG. 6, instead of the main body portion 3 of FIG. 1, for example, a cylindrical support member 7 that is an arm portion of a desk lamp supports a light source 1 and a light source substrate 2 on which the light source 1 is mounted. The support member 7 is preferably made of, for example, a rigid metal or resin, but may be bent. Inside the support member 7, wiring for supplying power to the light source 1, drive circuit and control circuit for driving the light source 1, rectifier circuit for rectifying commercial AC power, and voltage conversion A converter may be built in. Further, the heat transfer performance from the light source 1 to the support member 7 can be improved by applying silicon grease or the like that reduces the thermal resistance to the contact surface between the support member 7 and the light source substrate 2. Good. Furthermore, in order to improve the heat dissipation performance of the heat transferred from the light source 1 to the support member 7, the support member 7 may be provided with a heat dissipation structure such as a plurality of grooves, fine patterns, and self-similar microstructures. In addition, although the supporting member 7 is illustrated in a columnar shape in FIG.

  In the present embodiment, the first cover member 5 is provided with a screw portion 51, and the first cover member 5 is screwed into the end portion of the support member 7 that supports the light source 1 and the light source substrate 2 by the screw portion 51. Can be attached. In the present embodiment, the first cover member 5 is attached to the support member 7 by the screw portion 51, but an elastic hook or the like is provided instead of the screw portion 51, thereby attaching the cover member 5 to the support member 7. May be.

  Further, in the present embodiment, a second cover member 6 having a light transmitting property and a diffusing property is provided to cover the periphery of the light source 1, the light source substrate 2, and the first cover member 5. The second cover member 6 is detachably attached to the support member 7 by, for example, screwing or the like. The light distribution distributed by the first cover member 5 is adjusted while suitably protecting the LED light bulb including the light source 1, the light source substrate 2, and the first cover member 5 by the second cover member 6. In other words, this embodiment makes it possible to form a desired light-emitting surface shape by using the second cover member 6 and the light distribution distributed by the first cover member 5. For example, when it is desired to emit light in a spherical shape, the shape of the second cover member 6 is formed in a spherical shape, and the LED including the light source 1, the light source substrate 2, and the first cover member 5 of the second cover member 6. A light bulb may be arranged. In this way, it is possible to make the light emitting surface of the lighting device have a spherical surface and emit light with a substantially uniform light distribution.

  In the present embodiment, the first cover member 5 and the second cover member 6 are detachably attached to the support member 7. Accordingly, the first cover member 5 and / or the second cover member 6 can be replaced with another shape cover member, and the light distribution can be changed.

  A third embodiment of the lighting device according to the present invention will be described with reference to FIG. FIG. 7 is a cross-sectional view of a lighting device according to a third embodiment of the present invention.

  In the second embodiment, the entire surface of the second cover member 6 is made of a translucent material. However, in the third embodiment, the second cover member is made of a partially different material. For example, as shown in FIG. 7, the upper half portion of the second cover member 61 (the portion facing the light irradiation surface of the first cover member 5) is the reflective surface 62, and only the lower half portion is translucent. This is a transmission surface 63.

  If comprised in this way, the standlight suitable for illuminating the downward direction, for example, a desk lamp can be provided. The inner surface of the reflecting surface 62 may be a mirror surface or a diffuse reflecting surface. Further, it is preferable that the transmission surface 63 is diffused so as to diffuse and transmit light.

  Also in this embodiment, the first cover member 5 and the second cover member 6 are detachably attached to the support member 7. Thus, for example, when it is desired to illuminate the lower part of the room or on the desk with a lighting device that illuminates widely including the upper part of the room as in the second embodiment, the second cover member 6 shown in FIG. May be replaced with the second cover member 61 shown in FIG.

A fourth embodiment of the present invention will be described with reference to FIG. FIG. 8 is a cross-sectional view of a lighting device according to a third embodiment of the present invention.
In the fourth embodiment, instead of the first cover member 5 in the second embodiment, a cover member for covering the light source 1 and the light source substrate 2 with a first cover member 52 having one or a plurality of holes formed therein. It is characterized by the use.

  For example, while realizing a wide light distribution that causes the light distribution of the lighting device to emit light also on the back side of the LED bulb in the emission direction (the side on which the support member 7 is attached), a peak is observed in the direction of the central axis A of the LED bulb. There is a case where it is desired to realize a biased light distribution.

  In the third embodiment, in order to obtain the above-described biased light distribution, holes are formed in the first cover member 52 at positions corresponding to the emission peak direction of the light source 1, or the positions are locally disposed. The directivity is reduced to reduce the diffusion performance and increase the directivity. Thereby, it is possible to locally increase the light distribution while having a wide light distribution.

  As a method of adjusting the light distribution by the first cover member 52, the light source of the first cover member can be used in addition to providing a hole in a part of the first cover member 52 or locally cutting it as described above. You may make it make the light-diffusion characteristic (namely, surface roughness) in the location corresponding to the output peak direction of 1 part small compared with another part.

  Thus, in this embodiment, it is possible to provide an illuminating device in which the light distribution is adjusted.

  Also in this embodiment, the first cover member 5 and the second cover member 6 are detachably attached to the support member 7. Accordingly, for example, when it is desired to more strongly illuminate the upper part of the room with the illumination device that uniformly illuminates the room as in the second embodiment, the first cover member 5 shown in FIG. 6 is shown in FIG. The first cover member 52 may be replaced.

  A fifth embodiment of the present invention will be described with reference to FIG. FIG. 9 is a view for explaining the light source arrangement according to the fourth embodiment of the present invention and the shape of the first cover member 5 when the light source arrangement is used. In the present embodiment, an example in which four light sources 1 are arranged two-dimensionally as shown in FIG. 9 is shown, but the present invention is not limited to this.

In the fifth embodiment, the cross-sectional shape of the cover member 5 is determined as follows. That is,
The light source 1 is arranged substantially symmetrically with respect to the rotational symmetry axis (center axis A) of the cover member 5, the distance including the light emitting surface of the light source 1 arranged farthest from the center axis A is r, and the plurality of light sources 1 are The distance from the intersection of the light source substrate 2 with the central axis A to the point P on the cover member 5 is R, the central axis A of the cover member 5 and the intersection of the light source substrate 2 and the point P on the cover member 5 When the angle formed by the line connecting the two is θ and the light emission intensity in the θ direction is E (θ), the shape cut by the plane including the central axis A of the cover member 5 is the polar coordinate system expressed by Equation 1 above. It is substantially similar to the shape to be expressed and is characterized in that the following equation 3 is satisfied when the maximum value of the emission intensity is E _max .

  The shape of the cover member 5 according to the above formula 3 is useful when, for example, a plurality of light sources 1 are used to obtain a uniform light distribution while ensuring brightness.

  That is, when a plurality of light sources 1 are used, the light emission area increases, the ratio of the light emission surface of the light source 1 to the cover member 5 increases, and the cover member 5 is located away from the rotational symmetry axis (center axis A). If the light emitting surface of the light source 1 exists, a uniform light distribution cannot be obtained. This is because the distribution of the amount of light received by the cover member 5 is more greatly affected by the position of the light emitting surface of the light source 1 than the light distribution of the light source 11.

  In order to solve this, in this embodiment, the light distribution is expanded by the size of the cover member 5 and the distance r from the intersection of the center axis A of the cover member 5 and the light source substrate 2 to the light emitting surface of the light source 1. The condition of the shape of the cover member 5 as shown in the above equation 3 is obtained so that it can be performed. The relationship between the above parameters is obtained by the experiment and examination of the present inventors.

  Further, when the light source 1 having a large light emitting area is used alone instead of a plurality, the farthest position of the light emitting surface of the light source 1 from the intersection of the central axis A of the cover member 5 and the light source substrate 2. It is also possible to apply the above equation 3 with r being r.

  As described above, according to this embodiment, even when a plurality of light sources or a light source having a wide light emitting area is used, a uniform and wide light distribution can be obtained.

  Needless to say, the above embodiments can be implemented in any combination.

DESCRIPTION OF SYMBOLS 1 ... Light source, 2 ... Light source board, 3 ... Main-body part, 4 ... Base, 5, 52 ... Cover member (1st cover member), 51 ... Screw part, 6, 61 ... 2nd cover member, 62 ... Reflection Part, 63 ... transmission part, 7 ... support member.

Claims (11)

In the lighting device,
And at least one light source and a cover member that covers the periphery of the light output portion of the light source and has translucency and light diffusibility, the cover member being a plane including the central axis of the cover member The cross section has a long oval shape in a direction perpendicular to the central axis, and the maximum dimension of the cover member in the direction orthogonal to the central axis is greater than the center of the dimension of the cover member in the central axis direction. An illumination device that is located on a light source side. 2. The lighting device according to claim 1, wherein the cover member has a distance R from the light source to a point P on the cover member, and connects the axis of rotational symmetry of the cover member and the point P on the light source and the cover member. When the angle formed by the line segment is θ and the emission intensity in the θ direction is E (θ), the cross-sectional shape on the plane including the central axis (rotation symmetry axis) of the cover member is a polar coordinate system, and θ is 60 ° or less. A lighting device characterized by having a shape represented by the following expression.

2. The illumination device according to claim 1, wherein a plurality of the light sources are disposed on the light source substrate substantially symmetrically with respect to a central axis of the cover member, and a light emitting surface of the light source disposed farthest from the central axis is disposed. R, the distance from the intersection with the central axis of the light source substrate 2 to the point P on the cover member 5, R, the central axis of the cover member, the intersection of the light source substrate and the point on the cover member. Illumination having a shape represented by the following equation, where θ is the angle formed by the connecting line segment, E (θ) is the emission intensity in the θ direction, and E _max is the maximum value of the emission intensity. apparatus.

  The lighting device according to claim 1, wherein the light source is an LED.   The lighting device according to claim 1, wherein a reflection member is provided on a surface of the light source substrate on which the light source is mounted. In the lighting device,
At least one or more light sources, a first cover member that covers the periphery of the light output portion of the light source and has translucency and light diffusibility, and a translucency that covers the periphery of the first cover member A second cover member,
The first cover member has an oval shape in which a cross section in a plane including the central axis of the first cover member is long in a direction perpendicular to the central axis, and the central axis of the first cover member The illuminating device is characterized in that a maximum dimension in a direction orthogonal to the center of the cover member is located closer to the light source than a center of the dimension in the central axis direction.   The lighting device according to claim 6, wherein the second cover member as a whole has translucency and diffusibility. 7. The illumination device according to claim 6 , wherein the second cover member includes a reflection part that reflects light from the light source and a transmission part that diffuses and transmits light from the light source. Lighting device. 7. The illumination device according to claim 6, wherein the first cover member has a distance R from the light source to a point P on the first cover member, the rotational symmetry axis of the first cover member, and the light source. Including the central axis (rotation symmetry axis) of the first cover member, where θ is the angle formed by the line segment connecting the point P on the first cover member and the light emission intensity in the θ direction is E (θ). An illuminating device having a shape expressed by the following expression when a cross-sectional shape in a plane is a polar coordinate system and θ is 60 degrees or less.

The lighting device according to claim 6, wherein a plurality of the light sources are arranged on the light source substrate substantially symmetrically with respect to the central axis of the first cover member, and the light sources are arranged farthest from the central axis. The distance including the light emitting surface is r, the distance from the intersection with the central axis of the light source substrate to the point on the first cover member is R, the central axis of the cover member, the intersection of the light source substrate and the point on the cover member Characterized in that it has a shape expressed by the following formula, where θ is the angle formed by the line connecting the two and θ, the emission intensity in the θ direction is E (θ), and the maximum value of the emission intensity is E _max. Lighting device.

  The lighting device according to claim 6, further comprising a support member for supporting the light source substrate, wherein the first and second cover members are detachably attached to the support member. A lighting device.

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