LED bulb
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- NIHON BOSAI SCHEMES INC
- Filing Date
- 2022-08-05
- Publication Date
- 2026-07-31
Smart Images
Figure 0007898161000001 
Figure 0007898161000002 
Figure 0007898161000003
Abstract
Description
Technical Field
[0001] The present invention relates to an LED bulb equipped with an LED light-emitting element, and more particularly to an LED bulb incorporating a storage battery such as a lithium-ion battery.
Background Art
[0002] In recent years, LED bulbs (bulb-type LED lighting) equipped with LED light-emitting elements have become widespread. LED bulbs consume significantly less power and have a longer service life compared to conventional incandescent bulbs and bulbs with built-in fluorescent lamps. Further, some of these LED bulbs incorporate a storage battery (battery) such as a lithium-ion battery (lithium-ion secondary battery) as shown in, for example, Patent Document 1, and are configured to emit light from the LED bulb using the power stored in the storage battery during a power outage or when removed from the socket, thereby having a function as an emergency light or a flashlight. That is, the LED bulb shown in Patent Document 1 includes an emergency light control module connected to an LED drive power source. In a state where the main power source is connected, the LED drive power source lights the LED using the power supply from the main power source and charges the battery. Then, when the main power source is disconnected during an emergency such as a power outage, the LED drive power source is switched to the power supply from the battery to light the LED.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] Incidentally, when using lithium-ion batteries as the built-in rechargeable batteries for LED light bulbs, lithium-ion batteries have the characteristic of being prone to degradation due to heat. On the other hand, LED light bulbs generate a significant amount of heat, and the heat generated from the LED light-emitting elements can be transferred to the rechargeable battery, potentially causing the battery temperature to rise and accelerating its degradation. Therefore, in LED light bulbs with built-in rechargeable batteries, it is necessary to adopt a structure that can effectively dissipate the heat generated by the LED light-emitting elements to the outside, thereby suppressing degradation of the rechargeable battery due to heat.
[0005] The present invention has been made in view of the above problems, and aims to provide an LED light bulb that has a simple configuration and can effectively dissipate the heat generated by the LED light-emitting element to the outside, thereby suppressing the deterioration of the built-in rechargeable battery due to heat. [Means for solving the problem]
[0006] To solve the above problems, the LED light bulb according to the present invention is a battery-integrated LED light bulb comprising: an LED substrate (10) having a plurality of LED light-emitting elements (12) mounted on its surface (10a); a translucent cover member (25) covering the surface (10a) side of the LED substrate (10); a hollow base (30) having a cylindrical casing (35) provided so as to cover the back (10b) side of the LED substrate (10) at one end (35b); a rechargeable battery (40) housed inside the base (30); and a base (50) connected to the other end (35a) of the casing (35). (1) The peripheral wall (35A) of the cylindrical casing (35) is provided with a plurality of elongated slits (36) radially arranged in the circumferential wall (35A) of the casing (35), the slits (36) having openings (36a or 36b) consisting of through holes formed only on one side wall in the circumferential direction of a recess (37) formed by recessing the peripheral wall (35A) of the casing (35) inward, and the openings (36a or 36b) are characterized in that they face one side in the circumferential direction.
[0007] According to the present invention, the casing covering the base housing the battery is provided with a plurality of slits having openings formed by through holes that extend in an elongated shape along the axial direction of the casing, thereby ensuring ventilation between the inside and outside of the base through the openings of the slits. Therefore, the heat-containing gas from the LED light-emitting element can be released to the outside of the base through the slits before it is transferred to the battery, thus preventing deterioration of the battery due to heat generated by the LED light-emitting element. In particular, in the present invention, the openings of the slits are formed only on one side wall in the circumferential direction of a recess formed by recessing the peripheral wall of the casing inward, and these openings face one direction in the circumferential direction. As a result, when the LED light-emitting element is emitting light, the heat generated from the LED light-emitting element causes heat-containing gas to be released to the outside of the base from each of the openings of the plurality of radially arranged slits, forming a gas flow (swirling airflow) that swirls in one direction in the circumferential direction within the base. By forming such a swirling airflow, heat generated from the LED light-emitting element can be more effectively released to the outside of the base, thereby more effectively suppressing the transfer of heat from the LED light-emitting element to the battery. This prevents the battery from being exposed to high temperatures and thus prevents thermal degradation.
[0008] Furthermore, in the LED light bulb of the present invention, the peripheral wall (35A) of the casing (35) is a wall portion with a circular cross-section perpendicular to the axial direction, the storage battery (40) inside the casing (35) is cylindrical in shape with the axial direction as its longitudinal direction, and the plurality of slits (36) may be formed in the peripheral wall (35A) at positions surrounding the outer circumference of the storage battery (40).
[0009] With this configuration, multiple slits are formed around the outer circumference of the cylindrical battery, creating a swirling gas flow (swirling airflow) around the battery in one direction in the circumferential direction. This swirling airflow effectively expels the gas surrounding the battery to the outside of the base. Therefore, the gas containing heat from the LED light-emitting element is released to the outside by the swirling airflow before it reaches the battery, thus more reliably suppressing the transfer of heat from the LED light-emitting element to the battery and preventing battery degradation due to heat.
[0010] Furthermore, in the LED bulb of the present invention, the peripheral wall (35A) of the casing (35) may have a shape in which its diameter gradually increases from the other end (35a) to the one end (35b), the recess (37) may have a shape in which its depth gradually increases from the other end (35a) to the one end (35b), and the opening (36a) of the slit (36) may have a shape in which its width gradually increases from the other end (35a) to the one end (35b).
[0011] In this configuration, the width of the slit opening gradually increases from the other end, which is the casing base side, to the one end, which is the LED substrate side. As a result, the width is larger on the side closer to the LED substrate on which the LED light-emitting element is mounted. This allows heat-containing gas from the LED light-emitting element to be more effectively released from the slit opening to the outside of the base, thereby more effectively suppressing the transfer of heat from the LED light-emitting element to the battery.
[0012] Furthermore, in the LED light bulb of the present invention, the storage battery (40) may be a lithium-ion secondary battery.
[0013] Generally, lithium-ion secondary batteries degrade when exposed to high-temperature environments above a certain temperature. However, in the LED light bulb of the present invention, by providing the slits with the above configuration, the heat generated from the LED light-emitting element can be effectively suppressed from being transferred to the battery, thereby preventing the battery from being exposed to high-temperature environments and preventing degradation due to heat.
[0014] The reference numerals in parentheses above indicate, for reference only, the corresponding reference numerals in the drawings of the embodiments described later. [Effects of the Invention]
[0015] According to the present invention, the LED light bulb has a simple configuration that allows the heat generated by the LED light-emitting element to be effectively dissipated to the outside, thereby suppressing the deterioration of the built-in rechargeable battery due to heat. [Brief explanation of the drawing]
[0016] [Figure 1] This figure shows the external configuration of an LED light bulb according to the first embodiment of the present invention. [Figure 2] This is a cross-section viewed from the direction of arrow AA in Figure 1. [Figure 3] This is a view of the cross-section as seen through arrow BB in Figure 1. [Figure 4] This is an enlarged view of section C in Figure 2. [Figure 5] This is a diagram showing the schematic configuration of the electrical circuit for an LED light bulb. [Figure 6] This diagram illustrates the operation of an LED light bulb, specifically showing the flow of gas within its base. [Figure 7] This diagram illustrates the operation of an LED light bulb, specifically showing the flow of gas within its base. [Figure 8] This figure shows an LED light bulb according to a second embodiment of the present invention. [Figure 9] This diagram illustrates the operation of an LED light bulb, specifically showing the flow of gas within its base. [Figure 10] This diagram illustrates the operation of an LED light bulb, specifically showing the flow of gas within its base. [Figure 11] Front view of the LED bulb. [Figure 12] Plan view of the LED bulb. [Figure 13] Bottom view of the LED bulb. [Figure 14] View showing a cross-section with the internal structure of the LED bulb omitted, which is a cross-sectional view corresponding to the arrow D-D view of FIG. 11.
Mode for Carrying Out the Invention
[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. 〔First Embodiment〕 FIG. 1 is a view showing the external configuration of an LED bulb according to the first embodiment of the present invention. Further, FIG. 2 is a view showing a cross-section taken along the arrow A-A of FIG. 1, FIG. 3 is a view showing a cross-section taken along the arrow B-B of FIG. 1, and FIG. 4 is an enlarged view of part C of FIG. 2. As shown in these figures, the LED bulb 1 of the present embodiment includes an LED substrate 10 on which a plurality (a large number) of LED light-emitting elements 12 are mounted on the surface 10a, a light-emitting part 20 having a translucent cover member (glove) 25 that covers the surface 10a side of the LED substrate 10, a hollow base 30 having a cylindrical casing 35 provided so that one end (lower end 35b described later) covers the back surface 10b side of the LED substrate 10, a storage battery (battery) 40 composed of a lithium-ion secondary battery housed inside the base 30, and a base 50 connected to the other end (upper end 35a described later) of the casing 35. It is an LED bulb with a built-in battery.
[0018] In FIG. 1, the LED bulb 1 is shown in a direction such that the light-emitting part 20 side is on the lower side and the base 50 side is on the upper side. Also, the end of the casing 35 on the LED substrate 10 side is defined as the lower end (one end of the present invention) 35b, the end on the base 50 side is defined as the upper end (the other end of the present invention) 35a, and the direction from one of the lower end 35b and the upper end 35a to the other (the vertical direction in FIGS. 1 and 3) is defined as the axial direction L of the LED bulb 1.
[0019] The cover member 25 is made of a translucent synthetic resin material and is formed in a roughly hemispherical (dome) shape, covering multiple (numerous) LED light-emitting elements 12 mounted on the LED substrate 10. The cover member 25 constitutes the light-emitting part 20 of the LED bulb 1. When the LED light-emitting elements 12 emit light, the light is diffused to the outside through the cover member 25, causing the entire light-emitting part 20 to emit light uniformly.
[0020] A partition wall 27 is provided on the back surface 10b of the LED substrate 10, separating the light-emitting part 20 from the base part 30. The partition wall 27 is a plate-shaped portion that separates the light-emitting part 20 from the base part 30, and has a plurality of openings 27a on its surface, allowing the inside of the light-emitting part 20 and the inside of the base part 30 to communicate through these openings 27a.
[0021] The base portion 30 is a hollow portion defined by a substantially cylindrical casing 35. The peripheral wall 35A of the casing 35 is a wall portion with a circular cross-section perpendicular to the axial direction. Furthermore, the peripheral wall 35A of the casing 35 has a shape in which its diameter gradually increases from the upper end 35a side to the lower end 35b side of the casing 35. The casing 35 can be a molded product made of synthetic resin, or it may be made of a thin sheet of metal such as aluminum, which has relatively high thermal conductivity.
[0022] Furthermore, a circuit board 60 on which electronic components 65 for configuring the power outage detection circuit 120, etc., which will be described later, are mounted is installed near the lower end 35b of the casing 35 inside the base 30 (directly above the partition wall 27). Note that in each figure, the wiring and connectors connecting the circuit board 60 to the LED board 10 and the storage battery 40 are omitted from the illustration.
[0023] The battery 40 installed within the base 30 is cylindrical in shape with its longitudinal direction in the axial direction, and is positioned so that its axis is located in the center of the base 30 when viewed from above. The battery 40 is positioned with its lower end 40b, which is one end in the axial direction L, near the circuit board 60 (directly above), and its upper end 40a, which is the other end in the axial direction L, near the base 50, so that it is positioned within the base 30 along almost the entire axial direction L.
[0024] In the LED bulb 1 of this embodiment, the peripheral wall 35A of the cylindrical casing 35 has multiple slits 36 radially arranged, each having an opening 36a, which is a long through-hole extending along the axial direction L, from the lower end 35b to the upper end 35a of the casing 35. In the illustration, eight slits 36 are provided at equal intervals along the circumferential direction of the peripheral wall 35A. As shown in Figure 2, the slits 36 have openings 36a formed only on one side wall in the circumferential direction (the side facing counterclockwise as shown in Figure 2) of a recess 37 created by recessing the peripheral wall 35A of the casing 35 inward, and these openings 36a face in one direction (the side facing counterclockwise as shown in Figure 2). That is, the other side wall 37a of the recess 37 (the side facing clockwise as shown in Figure 2) is closed and does not have an opening.
[0025] Here, the configuration of the electrical circuit in the LED light bulb 1 of this embodiment will be described. Figure 5 is a block diagram showing the schematic configuration of the electrical circuit of the LED light bulb. The LED light bulb 1 of this embodiment can be used as a lighting fixture in the same way as a normal LED light bulb or a fluorescent light bulb by attaching the base 50 to a light bulb socket (not shown) inside a building or the like and receiving a supply of commercial power (AC power). When AC power is supplied from the light bulb socket, the power supplied from the AC power through the base 50 is converted to DC power by the AC / DC converter 100 and supplied to the LED light-emitting element 12 via the DC / DC constant current supply module 130 to make it light up, and the storage battery 40 can be charged. On the other hand, when the AC power is cut off, such as in the event of a power outage, the power outage detection circuit 120 detects that the AC power has been cut off and supplies DC power from the charged storage battery 40 to the LED light-emitting element 12 to make it light up. This makes it possible to use the LED light bulb 1 as an emergency light during a power outage.
[0026] By removing the base 50 of the LED bulb 1 from the power socket and short-circuiting the terminals of the base 50, the power outage detection circuit 120 can detect that the AC power has been cut off, allowing the LED bulb 1 to light up. This allows the LED bulb 1 to be used as a portable lighting device. Although not shown in the diagram, if a dedicated socket with a built-in switch for short-circuiting the terminals of the base 50 is attached to the base 50, the light can be switched on and off by turning the switch on and off, allowing the LED bulb 1 to be used as a battery-powered portable LED lamp or the like.
[0027] The LED light bulb 1 of this embodiment is a battery-integrated LED light bulb comprising an LED substrate 10 having a plurality of LED light-emitting elements 12 mounted on its surface 10a, a translucent cover member 25 covering the surface 10a side of the LED substrate 10, a hollow base 30 having a cylindrical casing 35 provided so as to cover the back surface 10b side of the LED substrate 10 at one end, a rechargeable battery 40 housed inside the base 30, and a base 50 connected to the upper end (other end) 35a of the casing 35. The peripheral wall 35A of the cylindrical casing 35 has a plurality of elongated slits 36 extending radially along the axial direction of the casing 35. These slits 36 have openings 36a, which are through holes formed only on one side wall 37a in the circumferential direction of a recess 37 formed by recessing the peripheral wall 35A of the casing 35 inward, and these openings 36a open facing one side in the circumferential direction.
[0028] In the LED bulb 1 of this embodiment, the casing 35 covering the base 30 housing the battery 40 is provided with a plurality of slits 36 having openings 36a formed by elongated through holes extending along the axial direction of the casing 35. This ensures ventilation between the inside and outside of the base 30 through the slits 36. Therefore, the heat-containing gas from the LED light-emitting element 12 can be released to the outside of the base 30 through the slits 36 before it is transferred to the battery 40, thus preventing deterioration of the battery 40 due to heat generated by the LED light-emitting element 12.
[0029] In particular, in the LED bulb 1 of this embodiment, the opening 36a of the slit 36 is an opening 36a formed only on one side wall 37a in the circumferential direction of a recess 37 formed by recessing the peripheral wall 35A of the casing 35 inward, and the opening 36a opens facing one side in the circumferential direction. As a result, when the LED light-emitting element 12 is emitting light, the heat generated from the LED light-emitting element 12 causes heat-containing gas to be released to the outside of the base 30 from each of the openings 36a of the multiple radially arranged slits 36, thereby forming a gas flow (swirling airflow) that swirls in one side in the circumferential direction within the base 30.
[0030] The above points will be explained in more detail with reference to the drawings. Figures 6 and 7 are diagrams illustrating the operation of the LED bulb and show the flow of gas within the base 30. The LED bulb 1 is often installed in a light bulb socket located at a high position, such as on the ceiling of a room, to illuminate downwards. Therefore, when used as lighting, it is often used with the light-emitting part 20 facing downwards and the base 50 facing upwards, as shown in these figures. When the LED light-emitting elements 12 mounted on the substrate 10 are emitting light, an upward airflow is generated inside the casing 35 of the base 30 due to the gas heated by the heat generated from these LED light-emitting elements 12. This upward airflow containing heated gas is released to the outside of the base 30 from each of the openings 36a of the multiple radially arranged slits 36 in the casing 35, as shown by arrow X1 in Figure 6. As a result, a gas flow (swirling airflow) that swirls in one direction in the circumferential direction is formed around the battery 40 inside the base 30, as shown by arrow Y1 in Figure 6 and arrow Z1 in Figure 7. The formation of this swirling airflow allows heat generated from the LED light-emitting element 12 to be more effectively released to the outside of the base 30. This effectively suppresses the transfer of heat from the LED light-emitting element 12 to the storage battery 40, preventing the storage battery 40 from being exposed to high temperatures and thus preventing thermal degradation.
[0031] Furthermore, in the LED bulb 1 of this embodiment, the peripheral wall 35A of the casing 35 is a wall portion with a circular cross-section perpendicular to the axial direction, the storage battery 40 inside the casing 35 is cylindrical in shape with the axial direction as its longitudinal direction, and the multiple slits 36 are formed in the peripheral wall 35A at positions surrounding the outer circumference of the storage battery 40.
[0032] With this configuration, multiple slits 36 are formed around the outer circumference of the cylindrical battery 40, creating a circular swirling gas flow (circular swirling airflow) around the battery 40 in one direction circumferentially. This circular swirling airflow allows the gas around the battery 40 to be discharged more effectively to the outside of the base 30. Therefore, the gas containing heat from the LED light-emitting element 12 is released to the outside by the circular swirling airflow before it reaches the battery 40, thus more effectively suppressing the transfer of heat from the LED light-emitting element 12 to the battery 40.
[0033] Furthermore, in the LED bulb 1 of this embodiment, the peripheral wall 35A of the casing 35 has a shape in which its diameter gradually increases from the upper end (other end) 35a side to the lower end (one end) 35b side, the recess 37 has a shape in which its depth gradually increases from the upper end (other end) 35a side to the lower end (one end) 35b side, and the opening 36a of the slit 36 has a shape in which its width gradually increases from the upper end (other end) 35a side to the lower end (one end) 35b side.
[0034] In this configuration, the slit 36 has a shape in which its width gradually increases from the upper end (other end) 35a side, which is the base 50 side of the casing 35, to the lower end (one end) 35b side, which is the LED substrate 10 side, so that the width dimension is larger on the side closer to the LED substrate 10 on which the LED light-emitting element 12 is mounted. As a result, the heat-containing gas from the LED light-emitting element 12 can be more effectively released from the slit to the outside of the base 30 at an earlier stage (before it reaches the battery 40), so that the heat generated from the LED light-emitting element 12 is more effectively suppressed from being transferred to the battery 40.
[0035] Furthermore, in the LED bulb 1 of this embodiment, the storage battery 40 is a lithium-ion secondary battery. Generally, lithium-ion secondary batteries have the characteristic of deteriorating when exposed to high-temperature environments above a predetermined temperature. However, by providing the slit 36 with the above configuration, the heat generated from the LED light-emitting element 12 can be effectively suppressed from being transferred to the storage battery 40, thus preventing the storage battery 40 from being exposed to high-temperature environments and preventing deterioration due to heat. In particular, lithium-ion batteries generally have an allowable temperature of about 45°C to 50°C, and if the heat generated by the LED light-emitting element 12 is significant, the temperature of the LED light-emitting element 12 and its surroundings may rise to near this allowable temperature. However, in the LED bulb 1 of this embodiment, the casing 35 of the base 30 is equipped with a slit 36 and an opening 36a that enable the above-mentioned effective heat dissipation, thereby effectively suppressing the temperature rise inside the base 30. Therefore, deterioration of the storage battery 40, which is made of lithium-ion batteries, can be avoided, and the durability of the LED bulb 1 as an emergency light can be improved.
[0036] Furthermore, since the LED light bulb 1 of this embodiment can be automatically turned on as an emergency light during a power outage, it can be used on a daily basis as an LED light bulb in places where lighting is needed in emergencies, such as areas that could serve as evacuation routes within the home, making it a useful LED light bulb in the event of a disaster.
[0037] Figures 11 to 14 are diagrams (design drawings) showing the LED bulb 1 of the first embodiment. Figure 11 is a front view, Figure 12 is a top view, Figure 13 is a bottom view, and Figure 14 is a cross-sectional view of the LED bulb 1 with the internal structure omitted, corresponding to the view taken by arrow DD in Figure 11. The right side view, left side view, and rear view of the LED bulb 1 are all shown symmetrically to the front view in Figure 11.
[0038] [Second Embodiment] Next, a second embodiment of the present invention will be described. In the description of the second embodiment and the corresponding drawings, the same reference numerals are used for components that are the same as or equivalent to those in the first embodiment, and detailed descriptions of those components will be omitted below. Furthermore, matters other than those described below, and matters not shown in the figures, are the same as in the first embodiment.
[0039] Figure 8 shows an LED bulb according to the second embodiment of the present invention, and is a cross-sectional view taken along the arrow at the position corresponding to AA in Figure 1. In the LED bulb 1 of the first embodiment, the slit 36 provided in the casing 35 has an opening 36a formed only on one side wall in the circumferential direction of the recess 37 (the side facing counterclockwise as shown in Figure 2), and the opening 36a opens facing that one side (the side facing counterclockwise). In contrast, in the LED bulb 1-2 of this embodiment, the slit 36-2 provided in the casing 35 has an opening 36b formed only on the other side wall in the circumferential direction of the recess 37-2 (the side facing clockwise as shown in Figure 7), and the opening 36b opens facing that other side (the side facing clockwise). Furthermore, one side wall 37b of the recess 37 (the side facing counterclockwise as shown in Figure 7) is closed and does not have an opening.
[0040] In other words, the LED bulb 1-2 of this embodiment differs from the LED bulb 1 of the first embodiment in that the opening 36b of the slit 36-2 provided in the casing 35 faces the opposite direction in the circumferential direction from the opening 36a of the slit 36 of the LED bulb 1 of the first embodiment.
[0041] Figures 9 and 10 are diagrams illustrating the operation of the LED bulb of the second embodiment, showing the flow of gas within the base. In the LED bulb 1-2 of this embodiment, when the LED light-emitting element 12 mounted on the substrate 10 is emitting light, an upward airflow is generated inside the casing 35 of the base 30 due to the gas heated by the heat generated from these LED light-emitting elements 12. This upward airflow containing heated gas is released to the outside of the base 30 from each of the openings 36b of the multiple radially arranged slits 36-2 in the casing 35, as shown by arrow X2 in Figure 9. As a result, a gas flow (swirling airflow) that swirls in one direction in the circumferential direction is formed around the storage battery 40 inside the base 30, as shown by arrow Y2 in Figure 9 and arrow Z2 in Figure 10. In this embodiment, the LED bulb 1-2 has an opening 36b in the circumferential direction of the casing (peripheral wall) that is opposite to the opening 36a of the LED bulb 1 in the first embodiment. Therefore, the direction of the airflow indicated by arrow X2, and the direction of the swirling airflow indicated by arrows Y2 and Z2 are also opposite. However, in all other respects, it operates the same as the LED bulb 1 in the first embodiment.
[0042] Although embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications are possible within the scope of the claims, specification, and drawings. [Explanation of symbols]
[0043] 1,1-2 LED light bulbs 10 LED boards 10a surface 10b back side 12 LED light-emitting elements 20 Light-emitting part 25 Cover component (globe) 27 Partition Wall 27a opening 30 base 35 Casing 35A Peripheral wall 35a Upper end (other end) 35b Lower end (one end) 36,36-2 Slit 36a opening 36b opening 37 Recess 37a side wall 37b side wall 40. Rechargeable batteries (lithium-ion secondary batteries) 40a top end 40b bottom end 50 nozzles 60 Circuit boards 65 Electronic Components 100 AC / DC Converter 120 Power outage detection circuit section 130 Constant Current Supply Module L axis direction
Claims
1. An LED substrate having multiple LED light-emitting elements mounted on its surface, A light-transmitting cover member that covers the surface side of the LED substrate, A hollow base having a cylindrical casing provided at one end to cover the back side of the LED substrate, The storage battery housed inside the base, A battery-powered LED light bulb comprising a base connected to the other end of the casing, The peripheral wall of the cylindrical casing has multiple slits along the circumferential direction of the peripheral wall, each slit having an opening consisting of an elongated through hole extending along the axial direction of the casing. The slit has an opening formed only on one side wall in the circumferential direction of a recess created by recessing the peripheral wall of the casing inward, and the opening is open facing one side in the circumferential direction. The peripheral wall of the casing has a shape in which its diameter gradually increases from the other end towards the one end. The recess has a shape in which its depth gradually increases from the other end towards the one end. The opening of the slit has a shape in which its width gradually increases from the other end to the one end. An LED light bulb characterized by the following features.
2. The peripheral wall of the casing has a circular wall portion with a cross-section perpendicular to the axial direction. The storage battery inside the casing has a cylindrical shape with the axial direction as its longitudinal direction. The multiple slits are formed in the peripheral wall at positions surrounding the outer periphery of the storage battery. The LED light bulb according to feature 1.
3. The storage battery is a lithium-ion secondary battery. The LED light bulb according to feature 1.