Lighting device

Abstract

This invention provides a lighting device that allows the use of existing equipment when converting to LED light sources, while also improving light distribution characteristics. [Solution] The LED lamp 10 of the lighting device 1 can utilize existing lighting fixtures 2 that use straight-tube fluorescent lamps, and is configured to distribute light in a circular direction around its axis, and can be dimmed to different brightness levels according to different time periods, with the brightness controlled to be dimmer in the second time period than in the first time period.

Description

Technical Field

[0001] The present invention relates to a lighting device provided with a straight tube type LED lamp.

Background Art

[0002] Conventionally, straight tube fluorescent lamps have been widely used as light sources for various lighting devices. Recently, with the spread of LEDs, lighting devices using LED lamps with low power consumption and long life as light sources are becoming the mainstream. Therefore, many straight tube type LED lamps standardized in the same manner as straight tube fluorescent lamps have already been proposed so that the power supply equipment for conventional straight tube fluorescent lamps can be used (see Patent Document 1). Such straight tube type LED lamps have been gradually switched from conventional straight tube fluorescent lamps, for example, also in the field of traffic lighting installed for general roads and highways.

[0003] Particularly, in the field of traffic lighting, tunnel lighting installed in tunnels has been recommended to be switched from conventional straight tube fluorescent lamps to straight tube LED lamps in combination with the special site environment inside the tunnels. In addition, since fluorescent lamps will be discontinued in the near future, switching to straight tube LED lamps has been an urgent task. In the case of tunnel lighting, the lighting fixtures (housings) are usually made of stainless steel and have high strength and are not easily deteriorated even after long-term use. Therefore, it has been required to continue using them as they are even after switching to straight tube LED lamps.

[0004] Also, in tunnel lighting, in order to ensure safe brightness inside the tunnel, even for straight tube LED lamps, it is important to have the same light distribution characteristics as conventional straight tube fluorescent lamps, so that light can be distributed in the circumferential direction around the axis and appear bright at 360 degrees. Regarding such conditions, the straight tube type LED lamp described in Patent Document 1 mentioned above has room for improvement because the back side of the LED substrate has a light distribution characteristic of becoming dark, and thus it could not be applied to tunnel lighting. As something that can solve such a problem, Andes Electric Co., Ltd. among the applicants of the present case has already proposed a new straight tube type LED lamp that emits light brightly in all 360-degree circumferential directions (see Patent Document 2).

[0005] Even when applying a straight-tube LED lamp like the one described in Patent Document 2 to tunnel lighting, its specific light distribution can be controlled in the same way as conventional straight-tube fluorescent lamps specifically designed for tunnel lighting. In other words, in general, tunnel lighting involves changing the lighting method of the straight-tube fluorescent lamps depending on whether it is daytime or nighttime to change the brightness.

[0006] More specifically, during the daytime, both of the two fluorescent lamps connected in parallel to the light fixture were fully dimmed (see Figure 7(a)), while at night, only one of the two fluorescent lamps was lit, using a half-dimming method (see Figure 7(b)). When only one lamp was lit, a dimming method was employed in which one of the two lamps was turned on alternately, taking into consideration the lifespan of the fluorescent lamps. In other words, the lighting of one of the fluorescent lamps was switched on and off alternately on a daily basis. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2015-065077 [Patent Document 2] Patent No. 6243998 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] However, when applying the straight-tube LED lamp described in Patent Document 2 mentioned above to tunnel lighting, if the same light distribution control as conventional straight-tube fluorescent lamps is used, the following problems arise, similar to those with conventional straight-tube fluorescent lamps. Specifically, when two fluorescent lamps are lit one at a time alternately during the night, the light distribution becomes completely different from when both fluorescent lamps are lit simultaneously during the daytime. In other words, when lit at night, the light distribution is biased to one side compared to the daytime, and this bias changes from day to day, so there was a need to eliminate this bias in light distribution.

[0009] This invention was made in response to the problems of the conventional technology described above. It is based on the premise that even after switching to LED lamps, the power supply equipment for conventional fluorescent lamps can be used, and the same light distribution characteristics as conventional fluorescent lamps can be achieved. Furthermore, it aims to provide a lighting device that can improve light distribution characteristics by allowing the brightness to be freely adjusted without bias or change in light distribution, even when the brightness is changed at different times of the day, such as when applied to tunnel lighting. [Means for solving the problem]

[0010] To achieve the aforementioned objectives, one aspect of the present invention is: In a lighting device equipped with a straight-tube LED lamp, The aforementioned LED lamp can utilize existing power supply equipment used to power straight-tube fluorescent lamps. The LED lamp, like the fluorescent lamp, is configured to distribute light in a circumferential direction around its axis. The LED lamp is characterized in that it can be dimmed to different brightness levels in a first time zone and a second time zone, and in the second time zone, it is controlled to be dimmer than the brightness in the first time zone. [Effects of the Invention]

[0011] According to the lighting device of this invention, costs can be reduced by utilizing conventional power supply equipment for fluorescent lamps, and the same light distribution characteristics as conventional fluorescent lamps can be easily achieved. Even when the brightness is changed to different levels for different time periods, the brightness can be freely adjusted without causing bias or changes in light distribution due to the change in brightness, and even better light distribution characteristics can be easily achieved. [Brief explanation of the drawing]

[0012] [Figure 1] This is a perspective view showing the LED lamp of a lighting device according to an embodiment of the present invention. [Figure 2]It is a plan view showing a lighting fixture of a lighting device according to an embodiment of the present invention. [Figure 3] It is a plan view showing an LED lamp of a lighting device according to an embodiment of the present invention. [Figure 4] It is a front view showing an LED lamp of a lighting device according to an embodiment of the present invention. [Figure 5] It is a side view showing an LED lamp of a lighting device according to an embodiment of the present invention. [Figure 6] It is a perspective view showing an LED lamp of a lighting device according to an embodiment of the present invention dividedly. [Figure 7] It is an explanatory view showing lighting control of an LED lamp of a lighting device according to an embodiment of the present invention. [Figure 8] It is a longitudinal sectional view showing an LED lamp of a lighting device according to an embodiment of the present invention. [Figure 9] It is a longitudinal sectional view showing a substrate holder of a lighting device according to an embodiment of the present invention. [Figure 10] It is an enlarged view of a main part of the configuration of the basic holder shown in FIG. 9. [Figure 11] It is an explanatory view showing the light distribution characteristics of an LED lamp of a lighting device according to an embodiment of the present invention. [Figure 12] It is an enlarged view of a main part showing the light distribution characteristics of the LED lamp shown in FIG. 11, particularly of the basic holder. [Figure 13] It is a longitudinal sectional view showing a modified example of the substrate holder shown in FIG. 9. [Figure 14] It is a plan view showing the mounting surface of a substrate before improvement of an LED of a lighting device according to an embodiment of the present invention, a side view, and a bottom view showing the back surface. [Figure 15] It is a plan view showing the mounting surface of a substrate after improvement of an LED of a lighting device according to an embodiment of the present invention, a side view, and a bottom view showing the back surface. [Figure 16] It is a longitudinal sectional view showing the mounting parts of substrates before and after improvement in an LED lamp of a lighting device according to an embodiment of the present invention. [Figure 17] It is a perspective view showing the assembly process of an existing LED lamp. [Figure 18]It is a perspective view showing an assembling process of an LED lamp of a lighting device according to an embodiment of the present invention. [Figure 19] It is a perspective view showing an enlarged structure of an end portion of an LED lamp of a lighting device according to an embodiment of the present invention. [Figure 20] It is a perspective view showing an enlarged and divided structure of an end portion of an LED lamp of a lighting device according to an embodiment of the present invention. [Figure 21] It is a perspective view showing an assembling process of an existing LED lamp. [Figure 22] It is a perspective view showing an assembling process of an LED lamp of a lighting device according to an embodiment of the present invention. [Figure 23] It is a longitudinal sectional view showing an assembling process of an LED lamp of a lighting device according to an embodiment of the present invention. [Figure 24] It is a longitudinal sectional view showing a completed form of an LED lamp of a lighting device according to an embodiment of the present invention. [Figure 25] It is an explanatory view showing an example of measurement results of illuminance during lighting of a conventional straight tube fluorescent lamp and an LED lamp of the present embodiment. [Figure 26] It is a block diagram schematically showing a control system of a lighting device according to an embodiment of the present invention. [Figure 27] It is an explanatory view showing dimming control of a lighting device according to an embodiment of the present invention. [Figure 28] It is a graph showing an example of control of a lighting device according to an embodiment of the present invention. [Figure 29] It is a graph showing an example of control of a lighting device according to an embodiment of the present invention. [Figure 30] It is a graph showing an example of control of a lighting device according to an embodiment of the present invention.

MODE FOR CARRYING OUT THE INVENTION

[0013] Hereinafter, representative embodiments of the present invention will be described based on the drawings. The lighting device 1 according to this embodiment is mainly composed of a straight-tube type LED lamp 10. The embodiments described below are examples, and the present invention is not limited to these embodiments. In each drawing, the relative dimensions and shapes of the components may be modified as appropriate in the design and may differ from the actual components. Also, hatching is omitted in the cross-sectional views. Detailed explanations of already well-known matters and redundant explanations of substantially identical components may be omitted as appropriate.

[0014] <Overview of Lighting Device 1> As shown in Figure 2, the lighting device 1 comprises a straight-tube LED lamp 10 and a lighting fixture 2, which is a power supply device for mounting and powering the LED lamp 10. The location and use of such a lighting device 1 are not particularly limited, but in this embodiment, the following description will specifically focus on its application to tunnel lighting installed inside tunnels as part of traffic lighting. Note that the lighting device 1 of this invention only needs to be equipped with an LED lamp 10, and the lighting fixture 2 itself is not an essential component.

[0015] <LEDランプ10> As shown in Figure 2, the LED lamp 10 is configured to mimic the shape of a conventional straight-tube fluorescent lamp. Specifically, the length of the LED lamp 10 should be set to 1198 mm, for example, to match the standard of a 40W type conventional straight-tube fluorescent lamp. The LED lamp 10 consists of a substrate 21 on which LEDs 20 are mounted, fixed via a substrate holder 30 inside a long, slender cylindrical outer tube 11 that extends in the axial direction.

[0016] As shown in Figure 8, the outer tube 11 is formed in a hollow cylindrical shape and is made of a translucent material that allows light from the LED 20 to pass through, such as a glass tube or a translucent synthetic resin. The outer tube 11 has a diffusion function to diffuse the light from the LED 20. As a result, the light from the LED 20 is diffused as it passes through the outer tube 11. Specifically, for example, it is preferable to attach a film to the inner surface of the outer tube 11 that also diffuses the light from the LED 20 and prevents damage.

[0017] <LED20 and Substrate 21> As shown in FIGS. 6 and 15, the substrate 21 on which the LED 20 is mounted is formed, for example, in a plate shape that extends in a narrow width by resin, and a plurality of LEDs 20 are arranged side by side on the mounting surface 21a on the surface side thereof. On the mounting surface 21a of the substrate 21, a plurality of LEDs 20 are arranged in a line along the length direction thereof so that the directions of the irradiated light are aligned. Note that the substrate 21 is not necessarily a single piece that extends integrally and long, and may be configured such that a plurality of divided pieces are arranged in series.

[0018] For example, a surface-mounted LED chip is suitable for the LED 20. More specifically, as shown in FIG. 16, the LED 20 is configured as an LED module in which an LED chip 20a, which is a light-emitting element, is sealed on a rectangular base 20b. The base 20b is provided with wirings that are electrically connected to an anode electrode and a cathode electrode (not shown) of the LED chip 20a. Each of the LEDs 20 is electrically connected to each other by a wiring 22 (see FIG. 15) formed by printing on the substrate 21. Note that the emission color of the LED 20 may be a single color such as white or may adopt a multi-color emission method of red, green, and blue, which are the three primary colors.

[0019] As shown in FIG. 18, a harness 23 that forms a wiring for supplying power to the LED 20 is connected to the end of the substrate 21. At the tip of the harness 23, another connector 24 is provided for connecting to one of the connectors 46 in the base portion 40 described later. As will be described later and as shown in FIG. 19, one of the connectors 46 in the base portion 40 is electrically connected to a terminal 44 that receives power from the lighting fixture 2. Therefore, by connecting the connector 24 at the tip of the harness 23 extending from the end of the substrate 21 to the connector 46 in the base portion 40, the LED 20 receives power supply from the outside.

[0020] [[ID=??]] <Heat dissipation via 25> As shown in Figures 15 and 16, the substrate 21 is provided with heat dissipation vias 25 that penetrate from the mounting surface 21a to the back surface 21b at a position that overlaps with the LED chip 20a in a plan view, and are used to dissipate the heat generated by the LED chip 20a. Normally, vias are used to transfer electricity between layers of a multilayer substrate, but the heat dissipation vias 25 in this embodiment are a means of dissipating heat generated by the LED chip 20a on the mounting surface 21a of the substrate 21 to the back surface 21b of the substrate 21. As will be described later, the heat dissipation vias 25 can suppress the temperature rise of the LED chip 20a by increasing the heat transfer efficiency to the outer tube 11.

[0021] The heat dissipation vias 25 are so-called through-holes that penetrate both the front and back surfaces of the substrate 21, and their inner surfaces are copper-plated, similar to ordinary vias. As shown in detail in Figure 16(b), on the mounting surface 21a of the substrate 21, in the area where the base 20b of the LED 20 is mounted, a total of nine heat dissipation vias 25 (see Figure 15) are arranged in a matrix of three on each side (front, back, left, and right). In addition, a heat sink plate 26 may be added to the area on the back surface 21b of the substrate 21 where the base 20b of the LED 20 overlaps in a plan view.

[0022] <Substrate holder 30> As shown in Figures 8 and 9, the substrate holder 30 fixes the substrate 21 to the inner wall of the outer cylindrical tube 11, and its overall shape is formed to cover the LED 20 substrate 21 in a dome shape, that is, in a substantially semi-cylindrical shape. The substrate holder 30 consists of a covering portion 31 that covers at least the mounting surface 21a side of the substrate 21, a pair of wrap-around support portions 32, 32 that wrap around to the back surface 21b side of the substrate 21 and support the substrate 21, and contact portions 33, 33 that conform to the shape of the inner wall of the outer cylindrical tube 11 and contact and fix it.

[0023] With this substrate holder 30, the substrate 21 of the LED 20 is held and its back surface 21b is covered by the wrap-around support parts 32, 32. Here, at least the mounting surface 21a side of the substrate 21 is covered by the covering part 31. As will be described in more detail later, the covering part 31 is configured to diffuse the light emitted from the LED 20 on its inside, widening the illumination angle and expanding the directivity.

[0024] As shown in detail in Figure 10, the wrap-around support portion 32 is composed of an upper support piece 32a and a lower support piece 32b so as to support the side edges of the substrate 21 of the LED 20 from both above and below. The specific shape and size of the wrap-around support portion 32 are not limited, but it is desirable that it be made of an elastic material or shape for clamping from above and below. The substrate 21 can be slid into the pair of wrap-around support portions 32 from one end of each wrap-around support portion 32.

[0025] In this embodiment, a contact portion 33 is integrally formed on the outside of the lower support piece 32b. The contact portion 33 abuts against and fixes the inner wall of the outer cylindrical tube 11. Here, the shape of the contact portion 33 is adapted to the shape of the inner wall of the outer cylindrical tube 11, that is, it is formed with the same curvature as the inner circumferential surface of the inner wall. Therefore, the substrate holder 30 enables easy positioning of the substrate 21 and the outer cylindrical tube 11.

[0026] In the substrate holder 30, the space between the pair of wrap-around support parts 32, 32 becomes the adhesive application area 34 where adhesive 35 is applied when fixing the substrate holder 30 to the outer cylindrical tube 11. In other words, adhesive 35 is applied to the part of the back surface 21b of the substrate 21 that is not covered by the substrate holder 30, and it is bonded to the outer cylindrical tube 11. Through this bonding with adhesive 35, the substrate 21 of the LED 20 is fixed to the inner circumferential wall of the outer cylindrical tube 11 via the substrate holder 30. As for the type of adhesive 35, a heat-dissipating adhesive with high thermal conductivity is used so as to efficiently transfer the heat generated by the LED 20 to the outer cylindrical tube 11.

[0027] Furthermore, in the structure of the substrate holder 30, at least the cover portion 31 is made of light-transmitting material. As a result, the light emitted from the LED 20 passes through the cover portion 31 and becomes transmitted light, which is emitted outward, and also diffuses within the substrate holder 30 and is emitted outward as diffused light, thus ensuring good light distribution at least towards the mounting surface 21a. The material of the substrate holder 30 is not particularly limited, but it is preferable to use a light-transmitting resin or the like for at least the cover portion 31, and more preferably for the entire material.

[0028] In particular, if the entire substrate holder 30 is made of a translucent material, then not only the covering portion 31 but also the wrap-around support portion 32 will be translucent, allowing the light emitted from the LED 20 to diffuse into the wrap-around support portion 32 that covers the back surface 21b of the substrate 21 from below (see Figure 12), and light will also be emitted onto the back surface 21b of the substrate 21. In other words, by using the substrate holder 30, the shadow of the substrate 21 on the back surface 21b can be made less noticeable, at least in the area covered by the substrate holder 30.

[0029] The configuration of the pair of wrap-around support parts 32, 32 in the substrate holder 30 is not limited to that shown in the figures. That is, as a modified substrate holder 300 of the substrate holder 30 described above, in addition to the configuration in which the side edges of the substrate 21 of the LED 20 are supported from both above and below, the wrap-around support part 320 may be a simpler configuration in which it simply supports the side edges of the substrate 21 from below, as shown in Figure 13.

[0030] <Socket part 40, lighting fixture 2> In Figure 1, although not visible due to being covered by caps 50 described later, the LED lamp 10 has a base portion 40 for mounting to a lighting fixture 2. The base portion 40 is the part that receives power from the lighting fixture 2 to make the LED 20 emit light, and is configured so that conventional lighting fixtures 2 for straight-tube fluorescent lamps can be used as is.

[0031] As shown in Figure 2, the lighting fixture 2 is configured to house two LED lamps 10 arranged in parallel inside its housing 3. Inside the housing 3, connection sockets 5 are provided on both sides of the mounting points 4 for the LED lamps 10, facing each other. A pair of terminals 44, 44 that receive power from the lighting fixture 2 are provided protruding outwards from the base portion 40, and each terminal 44 is fitted into a pin hole in the socket 5. A constant current power supply 60, which will be described later, is also provided inside the housing 3.

[0032] As shown in Figures 18 and 22, the nozzle portion 40 is configured in a substantially cylindrical shape with an open end and a bottom wall 43a at the other end. More specifically, a flange 41 is provided protruding around the outer circumference of the nozzle portion 40 at a point along its axial direction. The nozzle portion 40 is formed such that the open end side of the flange 41 forms an inner fitting portion 42 that fits inward from the end of the outer cylindrical tube 11, and the bottom wall 43a side of the flange 41 forms a small-diameter portion 43 with a smaller outer diameter than the inner fitting portion 42.

[0033] The overall shape of this base portion 40 is significantly smaller compared to the base portion of existing straight-tube LED lamps. For example, in the existing straight-tube LED lamp 70 shown in Figure 17, the base portion 71 was relatively long in the axial direction. In such a configuration, a wiring connector 72 was usually extended from the base portion 71 side and connected to the LED substrate 73 inside the glass tube. In contrast, in the LED lamp 10 of this embodiment, in order to achieve the same light distribution as conventional straight-tube fluorescent lamps, it was necessary to make the illumination area similar not only in the circumferential direction but also in the longitudinal direction.

[0034] Therefore, as shown in Figure 18, by shortening the overall length of the base portion 40 in the axial direction to the minimum extent possible, the length of the outer cylinder 11 is secured to the maximum extent possible within the standardized length range, thereby widening the illumination area of ​​the LED lamp 10 in the longitudinal direction. In this configuration, if the overall length of the base portion 40 is simply shortened, excess harness will be exposed around the connector joint. As a result, when the lamp is lit, the harness casts a shadow on the outer cylinder 11. To prevent this shadow from forming, the wiring structure between the substrate 21 of the LED 20 and the electrodes inside the base portion 40 is modified, as will be described later.

[0035] Furthermore, as shown in Figures 21 and 22, as part of miniaturizing the overall shape of the base portion 40, the maximum outer diameter of the base portion 40 has also been reduced to the minimum compared to the base portion of existing straight-tube LED lamps. For example, in the existing straight-tube LED lamp 70 shown in Figure 21, a resin base portion 71 was fitted onto the end of the outer tube 11, and a metal, non-combustible cap 74 was fitted over the outer circumference of the base portion 71. Therefore, in the circled area in Figure 21, the base portion 71 and the cap 74 overlap on the outside of the outer tube 11, creating a double structure, and the maximum outer diameter of the base portion 71 was also enlarged.

[0036] In this embodiment, the nozzle portion 40 is constructed by dividing it into an inner fitting portion 42 and a small-diameter portion 43 in the axial direction, thereby eliminating the double structure on the outer circumference side of the nozzle portion 71 and reducing the maximum outer diameter of the nozzle portion 40 to the minimum. That is, as shown in Figure 22, the inner fitting portion 42 of the nozzle portion 40 that is fixed to the outer cylinder 11 is fitted inside the outer circumference of the outer cylinder 11 without covering it. Therefore, the nozzle portion 40 does not protrude beyond the outer circumference of the outer cylinder 11. Here, the protruding width of the flange 41 is set to be approximately the same as the thickness of the outer cylinder 11.

[0037] In this manner, the non-combustible cap 50 is fitted over the end of the outer cylindrical tube 11, where the inner fitting portion 42 is housed, extending to the small-diameter portion 43 of the nozzle portion 40. Here, since the small-diameter portion 43 has a smaller outer diameter than the inner fitting portion 42, the outer circumference of the cap 50 does not protrude significantly beyond the outer circumference of the nozzle portion 40, unlike the double structure of the existing nozzle portion 71 and cap 74.

[0038] As shown in Figures 22 and 23, the cap 50 is constructed as a bottomed cylindrical shape from a metal such as aluminum. More specifically, the cap 50 is formed such that the outer diameter of the portion 51 that covers the end of the outer cylindrical tube 11 in which the inner fitting portion 42 is housed, and the portion 52 that covers the small diameter portion 43, are staggered and have different minimum diameters. Two small holes 53 (see Figure 1) are provided on the end face (bottom portion) of the outer portion 52 of the cap 50 for inserting the terminals 44 of the mouth portion 40, which will be described next.

[0039] As shown in Figure 18, the base portion 40 has a pair of conductive pins protruding parallel to each other as terminals 44 that are attached to the socket 5 of the lighting fixture 2, on the outside of the bottom wall 43a on the small diameter portion 43 side. Each terminal 44 receives power from a constant current power supply 60 inside the lighting fixture 2 to make the LED 20 light up. That is, by attaching the terminals 44 to the socket 5 of the lighting fixture 2, the terminals 44 become capable of receiving power from the constant current power supply 60. The terminals 44 are provided in the same shape as the pins of conventional straight-tube fluorescent lamps that are standardized according to JIS standards, for example.

[0040] As shown in Figure 20, a lighting board 45 for illuminating the LED 20 is provided inside the base portion 40. The lighting board 45 is connected to terminals 44 by lead wires, and the power received by terminals 44 is supplied to the lighting board 45. Outside the bottom wall 43a of the base portion 40, a connector 46 is provided between the pair of pins that make up terminals 44 to supply power received by terminals 44. The connector 46 is integrally connected to the lighting board 45, and the power received by terminals 44 is supplied from the lighting board 45 to the LED 20 side via the connector 46, as described below.

[0041] Also, as shown in FIGS. 19 and 20, on the bottom surface wall 43a of the base portion 40, near the connector 46, an insertion hole 47 is provided for inserting a harness 23 extending from the end of the substrate 21 to a position close to the base portion 40 to the outside of the base portion 40. The harness 23 passed through the insertion hole 47 is bent along the outside of the bottom surface wall 43a of the base portion 40, and the other connector 24 at the tip of the harness 23 is connected to the aforementioned one connector 46. In this way, by connecting the two connectors 24 and 46 to each other, the constant current power supply 60 and the substrate 21 of the LED 20 are connected, and power is supplied from the constant current power supply 60 to the LED 20. Details of the specific lighting control of the constant current power supply 60 and the LED 20 will be described later.

[0042] <Assembly Structure of LED Lamp 10> As shown in FIG. 22, on the outer peripheral surface of the inner fitting portion 42 of the base portion 40, a plurality of slits 48 are formed to create a gap with the inner wall of the end portion of the outer cylinder tube 11. Each slit 48 is continuously provided in the circumferential direction parallel to the axial direction. This slit 48 is a structure for allowing an adhesive for fixing the outer peripheral surface of the inner fitting portion 42 to the inner wall of the end portion of the outer cylinder tube 11 to penetrate. The fixing of the base portion 40 to the end portion of the outer cylinder tube 11 is configured to be performed simultaneously with the fixing of a cap 50 covering the base portion 40.

[0043] The base portion 40 is a resin mold, and even if it has a complex uneven structure, it can be integrally molded relatively easily. Specifically, for example, polybutylene terephthalate (PBT) is a resin suitable for the base portion 40. The characteristics of this polybutylene terephthalate are high heat resistance, excellent electrical insulation, good moldability, and high dimensional stability. Also, by externally fitting a metal cap 50 to the base portion 40, it is possible to ensure non-combustibility.

[0044] <Control System of LED Lamp 10> Figure 26 is a schematic block diagram showing the control system of the LED lamp 10 according to this embodiment. As shown in Figure 26, the LED lamp 10 is supplied with power from a constant current power supply 60, as described above, and the constant current power supply 60 is controlled by a controller 100, which is a control unit. The constant current power supply 60 receives power from an external power source such as a commercial power supply and supplies power to the LED lamp 10. Here, the power from the external power source is generally an AC voltage, but it is converted to DC by the constant current power supply 60, and the current is controlled to be constant regardless of the voltage. The constant current power supply 60 is capable of handling a wide range of rated input voltages (for example, AC 200 to 265V).

[0045] The power supply from the constant current power supply 60 to the LED lamp 10 is controlled by a controller 100, which is a control unit. The constant current power supply 60 includes a power supply board 61 that controls the power supply based on instructions from the controller 100. The power supply board 61 has several main functions, such as a switching function that switches the brightness of the LED lamp 10 to different levels in a first time zone and a second time zone in response to a step dimming instruction from the controller 100.

[0046] Specifically, the controller 100 consists of, for example, a CPU and a microcomputer (MPC) equipped with memory such as ROM and RAM where programs (software) executed by the CPU are stored. The various controls performed by the controller 100 described below are realized by the CPU executing programs. Note that the controller 100 does not need to be installed inside the lighting fixture 2, but can be installed, for example, at a suitable location near the site where the lighting device 1 is installed (inside the tunnel).

[0047] In this embodiment, the first time period is defined as, for example, daytime, and the second time period is defined as, for example, nighttime. In addition, in this embodiment, a third time period is defined as, for example, late nighttime. For each of these time periods, the dimming mode for the brightness of the LED lamp 10 when it is lit is set to be different in advance. Specifically, the brightness of the LED lamp 10 is set to 100% of a predetermined maximum value as the first dimming mode in the first time period (daytime), to 49% of a predetermined maximum value as the second dimming mode in the second time period (nighttime), and to 32% of a predetermined maximum value as the third dimming mode in the third time period (late nighttime).

[0048] In the constant current power supply 60, the switching function of the power supply board 61 supplies power to the LED 20 with a ratio adjusted for each dimming mode, based on the step dimming instructions from the controller 100 corresponding to each dimming mode. As shown in detail in Figure 27, when the step dimming 1 input of the switching function of the constant current power supply 60 is turned OFF and the step dimming 2 input is also turned OFF in response to the step dimming instruction for the first dimming mode from the controller 100, power (for example, 202mA) of the non-dimming current value (ratio 100%) for the first dimming mode is supplied to the LED 20.

[0049] Furthermore, when the controller 100 issues a step dimming instruction for the second dimming mode, the constant current power supply 60, when the step dimming 1 input of the switching function is turned ON and the step dimming 2 input is turned OFF (or the same applies when the step dimming 1 input is OFF and the step dimming 2 input is ON), supplies power (e.g., 99mA) to the LED 20 at a step dimming 1 current value (or the step dimming 2 current value) adjusted to the ratio of the second dimming mode (49%). In this way, the brightness of the LED 20 for each time period is set so that in the second time period (night), the brightness is approximately half that of the first time period (daytime).

[0050] Furthermore, when the controller 100 issues a step dimming instruction for the third dimming mode, and the step dimming 1 input of the switching function of the constant current power supply 60 turns ON, and the step dimming 2 input also turns ON, power (for example, 65mA) of the step dimming 3 current value, adjusted to the ratio of the third dimming mode (32%), is supplied to the LED 20. In this way, the brightness of the LED 20 during the third time period (midnight) is set to be dimmer than the brightness during the second time period (nighttime). Note that the third time period (midnight) is not particularly necessary and can be omitted.

[0051] Regarding the dimming of these LED lamps 10 (LED20), in any mode, all of the multiple LED lamps 10 in a single lighting device 1 will light up at the brightness described above for each mode. In other words, it is not possible to light up only some of the multiple LED lamps 10. As a result, there is no risk of the light distribution being different from that of the daytime simultaneous lighting of two fluorescent tubes, which occurs when two fluorescent tubes are lit alternately each day, as is the case with conventional fluorescent tube lighting control at night.

[0052] Incidentally, the controller 100 can be set for each of the aforementioned time periods by, for example, an annual program timer related to sunrise and sunset times, and each time period differs slightly from day to day. As for the specific timing of switching each dimming mode for each time period, for example, if there is no third time period (midnight), then for example, the switch will occur 30 minutes after sunset from the first time period (daytime) to the second time period (nighttime), and 30 minutes before sunrise from the second time period (nighttime) to the first time period (daytime).

[0053] Furthermore, if there is a third time zone (nighttime), for example, the 30 minutes from sunset would be designated as the second time zone (nighttime), 30 minutes after sunset as the third time zone (nighttime), 30 minutes before sunrise as the second time zone (nighttime), and 30 minutes after sunrise as the first time zone (daytime).

[0054] <<Soft Start Function at Boot-Up>> In this embodiment, the controller 100 is also configured to control the lighting of the LED lamp 10 by gradually increasing the current supplied from the constant current power supply 60 to the LED lamp 10 to a target current value after startup.

[0055] As shown in detail in Figure 28, after the constant current power supply 60 is powered on, it is possible to control it to maintain a pre-initialized startup current value (e.g., 58% of the target output current value) for, for example, 1 second, and then transition to the target output current value over a predetermined transition time (value A in the figure). Here, the transition time can be appropriately set, for example, to 2 seconds, by operating the controller 100. If it is desired to reach the target current value immediately after power-on, this can be achieved by setting the transition time (value A in the figure) to 0 and setting the startup current value to the same value as the target current value.

[0056] <<Soft start function during switching>> Furthermore, in the controller 100 of this embodiment, the length of the transition time required for switching when the dimming mode of the LED 20 changes for each time period is set to be adjustable for controlling the lighting of the LED lamp 10.

[0057] For details, see Figure 29. In the figure, the "initial illuminance correction setting current value" corresponds, for example, to the non-dimming current value of the first dimming mode in the first time period (daytime) as described above, and the "step dimming current value" in the figure corresponds, for example, to the step dimming 1 current value (step dimming 2 current value) of the second dimming mode in the second time period (nighttime) as described above. Here, it is possible to adjust the predetermined transition time (value B in the figure) for switching to each dimming mode. Here, the transition time can also be appropriately set, for example, to 2 seconds, by operating the controller 100.

[0058] <<Initial Illumination Correction Function>> Furthermore, the controller 100 of this embodiment may also be configured to include a function that accumulates the time the power is turned on and outputs an initial illuminance correction setting value corresponding to that time. The setting value here should be set within the range of current values ​​that allow the LED 20 to be dimmed.

[0059] As shown in Figure 30 for details, for example, the operating time is accumulated in 10-minute increments and set to count up to a maximum of 200,999 hours and 50 minutes. After this maximum time, it is advisable to set the system to maintain the maximum current value. With this function, it is possible to appropriately adjust the power supply current value to an optimal value in accordance with the degradation of the LED 20.

[0060] <Operation of Lighting Device 1> The operation of the lighting device 1 according to this embodiment will be described below. First, to assemble the LED lamp 10, which is the main component of this lighting device 1, a circuit board 21 on which the LEDs 20 are mounted is prepared. In this lighting fixture 2, which is applied to tunnel lighting, the LED lamp 10, which generates heat, is lit inside a sealed housing 3. Also, heat tends to build up inside tunnels, creating a harsh environment for the LEDs 20. As a result, the temperature of the LEDs 20 may rise, shortening their lifespan, or they may fail if they reach the junction temperature. Therefore, when applied to tunnel lighting, heat dissipation of the LEDs 20 is especially essential.

[0061] Therefore, in order to transfer the heat generated by the LED 20 to the back surface 21b of the substrate 21, a substrate 21 equipped with heat dissipation vias 25 as shown in Figure 16 is adopted. The heat dissipation vias 25 on the substrate 21 can improve the efficiency of heat conduction from the LED 20 to the outer tube 11, and can suppress the rise in the heat generated when the LED 20 is lit. This makes it possible to prevent deterioration of the LED 20 due to heat generation as much as possible and extend its lifespan. In the inventors' measurement results, it was confirmed that the heat dissipation function of the heat dissipation vias 25 reduces the cathode temperature of the LED chip 20a to 6.3°C near the center of the LED lamp 10 and to 15.0°C on the non-powered side.

[0062] As shown in Figure 8, the LED 20 substrate 21 is attached to the substrate holder 30 and fixed to the inner wall of the outer tube 11 by adhesive applied to the adhesive application area 34 between the pair of wrap-around support parts 32, 32. At this time, the substrate holder 30, which has the same curvature as the inner wall of the outer tube 11, makes it easy to position the substrate 21 and the outer tube 11. In addition, the adhesive can be applied to an area narrower than the width of the substrate 21, and the amount of adhesive used can be reduced to the minimum necessary amount.

[0063] A nozzle portion 40 is attached to one end and the other end of the outer cylindrical tube 11 to which the substrate 21 is fixed. As shown in Figure 18, the nozzle portion 40 is formed in two parts: an inner fitting portion 42 that fits into the outer cylindrical tube 11 on the open end side of the flange 41 midway along the axial direction, and a small-diameter portion 43 with a smaller outer diameter on the bottom wall 43a side of the flange 41. With such a nozzle portion 40, the nozzle portion 40 and the cap 50 do not overlap on the outside of the end of the outer cylindrical tube 11, and the maximum outer diameter of the nozzle portion 40 can be reduced to the minimum.

[0064] As shown in Figures 19 and 20, the harness 23 extending from the end of the substrate 21 of the LED 20 is pulled out to the outside through the insertion hole 47 in the base portion 40. Then, with the harness 23 bent along the bottom wall 43a of the base portion 40, the connector 24 at the end of the harness 23 is connected to the connector 46 on the base portion 40 side. As a result, as described above, the harness 23 does not cast a shadow on the end of the outer tube 11, and good light distribution characteristics can be achieved along the entire length of the LED lamp 10.

[0065] Furthermore, the fixing of the nozzle portion 40 to the end of the outer cylindrical tube 11 can be done simultaneously with the fixing of the cap 50 that is placed over the nozzle portion 40. As shown in Figure 23, the cap 50 is fixed from the small diameter portion 43 of the nozzle portion 40 to the end of the outer cylindrical tube 11 by adhesive 49 applied to the light gray area shown on its inside. At this time, as shown in Figure 24, when the cap 50 is placed over the small diameter portion 43 of the nozzle portion 40 and pressed in, the small diameter portion 43 of the nozzle portion 40 is simultaneously fixed to the inner wall of the end of the outer cylindrical tube 11 by the adhesive 49 that has entered the slit 48. In this way, the nozzle portion 40 and the cap 50 can be bonded to the end of the outer cylindrical tube 11 simultaneously, without having to bond them separately.

[0066] As described above, with the completed LED lamp 10, as shown in Figure 2, the light source of this lighting device 1 can be changed from a conventional straight-tube fluorescent lamp to an LED by using the existing tunnel lighting fixture 2 as is. In other words, by switching from a conventional fluorescent lamp to an LED lamp 10, it is possible to easily achieve the same light distribution characteristics as a conventional fluorescent lamp by taking advantage of the characteristics of LEDs. Here, by standardizing the base portion 40 and terminals 44 of the LED lamp 10 to the same shape as those of a conventional straight-tube fluorescent lamp, it becomes possible to use the existing lighting fixture 2 as is without any special modifications, and equipment costs can be reduced significantly.

[0067] Regarding the light distribution of the LED lamp 10, which is a new light source of this lighting device 1, as shown in Figure 8, by fixing the substrate 21 of the LED 20 to the inner wall of the outer tube 11 via the substrate holder 30, it is possible to achieve light distribution characteristics similar to those of a conventional straight-tube fluorescent lamp. In other words, the LED lamp 10 makes it possible to distribute light over the entire 360 ​​degrees in the circumferential direction around its axis. As mentioned above, the light from the LED 20 can obtain good light distribution characteristics not only on the mounting surface 21a side of the substrate 21, which is the direction of emission, but also in the region where the back surface 21b of the substrate 21 faces.

[0068] As shown in detail in Figures 11 and 12, the light emitted by the LED 20 passes through the inside of the substrate holder 30, then through the outer cylindrical tube 11, and is irradiated to the outside of the outer cylindrical tube 11. In other words, the substrate holder 30 is translucent and also has an internal reflective effect depending on the angle of incidence, so it also functions as a light guide tube and has a light diffusion effect. Therefore, illumination can also be achieved by passing through the wrap-around support portion 32 that covers a part of the back side of the substrate 21. Furthermore, since the outer cylindrical tube 11 also has translucency and diffusion functions, the light that has passed through the substrate holder 30 is irradiated over a wider area via the outer cylindrical tube 11.

[0069] In particular, if the entire substrate holder 30 is made of a translucent material, then not only the covering portion 31 but also the wrap-around support portion 32 will be translucent. As a result, the light emitted from the LED 20 will diffuse into the wrap-around support portion 32 that covers the back surface 21b of the substrate 21 from below, and light will also be emitted to the area opposite the back surface 21b of the substrate 21. This makes it possible to obtain good light distribution characteristics on the back surface 21b of the substrate 21 without any shadow being cast on the substrate 21.

[0070] Moreover, as mentioned above, with the LED lamp 10 of this embodiment, unlike the existing straight-tube LED lamp 70 shown in Figure 17, the ends of the outer tube 11 are not extensively covered in the axial direction by the long base portion 71 at both ends in the longitudinal direction. Furthermore, by minimizing the axial length of the base portion 40, localized shadows of the harness 23 do not occur at the ends of the outer tube 11, and good light distribution can be obtained.

[0071] Figure 25 shows an example of illuminance measurement results from an experiment conducted by the inventors of this invention, comparing a conventional straight-tube fluorescent lamp with the LED lamp 10 of this embodiment when lit. The illuminance measured here depends on the distance and angle from the light source; the closer the distance from the light source, the higher the illuminance, and the farther away, the lower it is. As is clear from the measurement results comparing the two lamps at distances of 1m, 2m, and 3m from the light source, it is evident that the LED lamp 10 can achieve almost the same light distribution characteristics as a conventional straight-tube fluorescent lamp at any distance.

[0072] When the lighting device 1, including the LED lamp 10 described above, is applied to tunnel lighting, the controller 100 shown in Figure 26 automatically performs dimming to change the brightness to different levels depending on whether it is daytime or nighttime. Specifically, the brightness of the LED lamp 10 is set to 100% of the maximum value as the first dimming mode during the first daytime period, to 49% of the maximum value as the second dimming mode during the second nighttime period, and further, if necessary, to 32% of the maximum value as the third dimming mode during the third late-night period. These specific brightness ratios are considered optimal values ​​in the field of tunnel lighting.

[0073] Regarding the dimming of these LED lamps 10, in both the daytime lighting mode shown in Figure 7(a) and the nighttime lighting mode shown in Figure 7(c), both LED lamps 10 in a single lighting device 1 will light up at the brightness level specified for each mode. In other words, as shown in Figure 7(b), it is not possible to light up only one of the two LED lamps 10. This eliminates the risk of alternating the lighting of two linear fluorescent lamps on different days, as is done with conventional linear fluorescent lamps during nighttime lighting control, resulting in a different light distribution from that of simultaneous daytime lighting. Furthermore, by suppressing the current value while keeping both lamps lit, it is possible not only to achieve the same light distribution but also to extend the lifespan of each LED lamp 10.

[0074] Furthermore, as control for the lighting of the LED lamp 10, as shown in Figure 28, the current supplied from the constant current power supply 60 to the LED lamp 10 may be controlled to gradually increase to a target current value after startup. Also, as shown in Figure 29, the length of the transition time required for switching when the dimming mode of the LED 20 changes for each time period may be adjustable. Alternatively, as shown in Figure 30, it is also possible to control the system to accumulate the time the power is turned on and output an initial illuminance correction setting value corresponding to that time.

[0075] <Structure and Effects of the Present Invention> The embodiments of the present invention have been described above, but the present invention is not limited to the embodiments described above. The present invention derived from the embodiments described above will be described below.

[0076] First, the present invention relates to a lighting device 1 equipped with a straight-tube type LED lamp 10, The LED lamp 10 can utilize existing power supply equipment for powering a straight-tube fluorescent lamp, The LED lamp 10 is configured to distribute light in a circumferential direction around its axis, similar to the fluorescent lamp. The LED lamp 10 is characterized in that it can be dimmed to different brightness levels in the first time period and the second time period, and in the second time period, it is controlled to be dimmer than the brightness in the first time period.

[0077] With this configuration, the light source of the lighting device 1 can be changed from a conventional straight-tube fluorescent lamp to an LED. Even after switching from a conventional fluorescent lamp to an LED lamp 10, the power supply equipment for the conventional fluorescent lamp can be used, and the same light distribution characteristics as the conventional fluorescent lamp can be easily achieved. In particular, even when changing the brightness to different levels for different time periods, it is possible to adjust only the brightness without causing bias or changes in light distribution due to the change in brightness, and good light distribution characteristics can be easily achieved.

[0078] Furthermore, in this invention, multiple LED lamps 10 are arranged in parallel. Each of the LED lamps 10 is characterized in that, during the first time period, they are all lit at a first dimming level, and during the second time period, they are all lit at a second dimming level, which is approximately half the brightness of the first dimming level.

[0079] With this configuration, it is not possible to light up only some of the multiple LED lamps 10 in a single lighting device 1. This eliminates the risk of alternating the lighting of two linear fluorescent lamps on different days, as is done with conventional linear fluorescent lamps during nighttime lighting control, which can result in a different light distribution than when both lamps are lit simultaneously during the day. Furthermore, the ratio of the brightness of the second dimming setting to approximately half the brightness of the first dimming setting is suitable for tunnel lighting.

[0080] Furthermore, in this invention, the LED lamp 10 is dimmable to different brightness levels in a third time period in addition to the first and second time periods, and in the third time period, it is controlled to be dimmer than the brightness in the second time period.

[0081] With this configuration, when a dimming mode corresponding to one of three time periods is selected from the predetermined brightness levels of the LED lamp 10—the first dimming mode, the second dimming mode, and the third dimming mode—different brightness levels can be achieved for each period. Note that the number of dimming modes is not limited to three.

[0082] Furthermore, this invention is characterized in that the length of the transition time required for the LED lamp 10 to switch brightness according to each time period can be adjusted.

[0083] This configuration eliminates the abruptness and discomfort caused by sudden changes in brightness when switching between time zones, allowing for smooth dimming. The length of the transition time required for switching can be freely adjusted; for example, if you want to switch immediately, you can set the transition time to 0.

[0084] Furthermore, in this invention, the LED lamp 10 is constructed such that a substrate holder 30, which holds a substrate 21 on which LEDs 20 are mounted, is fixed to the inner wall of an outer cylindrical tube 11 by an adhesive applied to the back side of the substrate 21. The substrate holder 30 has an overall shape that is substantially semi-cylindrical and comprises a covering portion 31 that covers at least the mounting surface side of the substrate 21, a pair of wrap-around support portions 32 that wrap around to the back side opposite the mounting surface of the substrate 21 to support the substrate 21, and a contact portion 33 that conforms to the shape of the inner wall of the outer cylindrical tube 11 and contacts and fixes it. The space between the pair of wrap-around support portions 32 is characterized in that it becomes the adhesive application area 34 when fixing the substrate holder 30 to the inner wall of the outer cylindrical tube 11.

[0085] With this configuration, by fixing the LED 20 substrate 21 to the inner wall of the outer tube 11 with adhesive via the substrate holder 30, it becomes possible to distribute light over the entire 360 ​​degrees in the circumferential direction around the axis, similar to conventional straight-tube fluorescent lamps. In other words, good light distribution characteristics can be obtained without shadows being cast by the substrate 21, not only on the mounting surface side of the substrate 21, which is the direction of light emission from the LED 20, but also in the area where the back side of the substrate 21 faces.

[0086] While embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to these embodiments, and any changes or additions that do not depart from the spirit of the present invention are also included. For example, in the above embodiments, two LED lamps 10 are provided, but the specific number of LED lamps 10 is not limited to two, and it is also possible to configure it to include three or more LED lamps 10.

[0087] Furthermore, regarding the control of the LED lamps 10, the system may be configured to allow manual control of the lighting of the LED lamps 10, not only in terms of automatic changes in brightness for different time periods, but also in cases such as when the road surface is dark due to heavy rain or cloudy weather (mainly in illuminated areas) or in response to accidents (mainly in tunnel areas), depending on the surrounding weather conditions. [Industrial applicability]

[0088] The lighting device according to this invention can be widely applied to lighting devices in various fields, not limited to tunnel lighting among traffic lighting, for example. [Explanation of symbols]

[0089] 1…Lighting device 2…Lighting equipment 10…LED lamps 11…Outer tube 20…LED 21… Circuit board 22...Wiring 23…Harness 24...the other connector 25…Via for heat dissipation 26…Heat sink 30... Circuit board holder 31... Covering part 32... Wrap-around support section 33…Contact part 40... Mouthpiece 41…Flange 42…Internal fitting part 43…Small diameter part 44... Terminals 45... Lighting board 46... One of the connectors 47…Through hole 48... Slit 50... Cap 60…Constant current power supply 70…Straight-tube LED lamp 71... Mouthpiece 100... Controller (control unit)

Claims

1. In a lighting device equipped with a straight-tube LED lamp, The aforementioned LED lamp can utilize existing power supply equipment used to power straight-tube fluorescent lamps. The LED lamp, like the fluorescent lamp, is configured to distribute light in a circumferential direction around its axis. The LED lamp is dimmable to different brightness levels in a first time zone and a second time zone, and the lighting device is characterized in that the brightness in the second time zone is controlled to be dimmer than the brightness in the first time zone.

2. Multiple LED lamps are arranged in parallel. The lighting device according to claim 1, characterized in that each of the LED lamps lights up at a first dimming level during the first time period, and each of the LED lamps lights up at a second dimming level that is approximately half the brightness of the first dimming level during the second time period.

3. The lighting device according to claim 1, characterized in that the LED lamp can be dimmed to different brightness levels in a third time period in addition to the first and second time periods, and in the third time period, the brightness is controlled to be dimmer than the brightness in the second time period.

4. The lighting device according to claim 1 or 3, characterized in that the length of the transition time required for the LED lamp to switch brightness according to each of the time periods can be adjusted.

5. The LED lamp consists of a substrate holder that holds a substrate on which LEDs are mounted, which is fixed to the inner wall of an outer cylindrical tube by an adhesive applied to the back side of the substrate. The substrate holder has an overall shape that is substantially semi-cylindrical and comprises a covering portion that covers at least the mounting surface side of the substrate, a pair of wrap-around support portions that wrap around to the back side opposite the mounting surface of the substrate to support the substrate, and a contact portion that conforms to the shape of the inner wall of the outer cylindrical tube and contacts and fixes it. The lighting device according to claim 1, characterized in that the space between the pair of wrap-around support portions becomes the adhesive application area when fixing the substrate holder to the inner wall of the outer cylindrical tube.

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