JP2017126439A - LED light bulb - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an LED light bulb capable of securing assemblability while preventing deterioration of light emitting characteristics even when a large-sized capacitor is arranged in a space in a light-emitting part.SOLUTION: In an LED light bulb 10, on an upper surface of a circuit board 16, a plurality of LED light sources 12 are mounted in a peripheral part, one capacitor 13 is mounted in the center, and electronic components such as an IC 15 are mounted on portions other than those. The capacitor 13 has a cylindrical shape and is upright, and electronic components are low and they are a surface mounting type. A globe 17 covers the upper surface of the circuit board 16 with these LED light sources 12 and the electronic components as a whole. One part of the light emitted from the LED light source 12 reaches an apex of the globe 17 without mechanically vignetting by the capacitor 13, and other part of the light reaches the globe 17 by being reflected on a side surface of the capacitor 13 without mechanically vignetting by the low electronic components.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an LED bulb using an LED as a light source.

  LED bulbs using LEDs as light sources are on the market. In many cases, the LED bulb has a base that is similar to the conventional incandescent bulb and has an overall shape similar to that of a conventional incandescent bulb, such as an incandescent bulb or a halogen lamp. Some LED bulbs are connected to a commercial AC power source, and the LED is turned on with an AC voltage obtained therefrom. Among the LED bulbs, there is an LED bulb that includes an LED string in which a large number of LEDs are connected in series, and a voltage waveform (full-wave rectified waveform) obtained by rectifying an AC voltage is applied to the LED string to light the LED ( So-called AC drive). The LED bulb adopting this AC drive has a feature that there is no smoothing circuit, so that it is not necessary to use an electrolytic capacitor that has a shorter life and a larger size than an LED.

  However, in an LED bulb employing AC driving, the LED string does not light up during a period when the full-wave rectified waveform does not reach the threshold value because the LED string has threshold characteristics. That is, flicker occurs by repeating the period in which the LED is lit and the period in which the LED is not lit. If the frequency of the commercial AC power source is 50 to 60 Hz, this flicker is doubled to 100 to 120 Hz. This frequency is often not perceived, but objects that move at high speed appear to flicker (motion breaks) and cause health damage to some people.

  Therefore, recently, it has been demanded to install a large capacitor in parallel with the LED array as a countermeasure against flicker even in an LED bulb adopting AC driving. In an LED light bulb that does not employ AC driving, an LED serving as a light source is usually disposed in a globe, and electronic components other than the LED are often housed in a case provided between the globe and the base. However, in the case of LED bulbs that use AC drive that are not premised on the use of large capacitors, there are cases where there is no place to store large capacitors in the base or case when trying to maintain the outer shape. is there. Therefore, it has been considered to arrange a large electrolytic capacitor in the space in the globe so that it is not necessary to change the outer shape of the LED bulb.

  In an LED bulb, when a light emitting unit is a part having a globe or a light source LED as a constituent element, it has been known for a long time to arrange a large electronic component in the internal space of the light emitting unit (for example, Patent Document 1). ). Then, FIG. 1 of patent document 1 is re-displayed in FIG. 7, and the structure is demonstrated. FIG. 7 is a schematic cross-sectional view showing the structure of a conventional LED bulb (illumination device). Note that () indicates terms used in Patent Document 1 (the same applies hereinafter). Moreover, in FIG. 7, the code | symbol in FIG. 1 of patent document 1 is changed.

  An LED bulb 70 shown in FIG. 7 includes a light emitting unit 78 including a light source unit 77, an insulating substrate 83, an outer reflecting member 80, a translucent unit 100, and a lighting circuit unit 73, a case 90 (heat dissipating unit), and a base unit 87. Become.

In the light emitting unit 78, the light source unit 77 includes a plurality of white LEDs 75 and an annular LED substrate 76, and the white LEDs 75 are mounted on the LED substrate 77. The insulating substrate 83 is mounted with the light source unit 77, the cylindrical outer reflecting member 80 is mounted so that the lower end (the other end 82) is in contact with the peripheral portion, and the lighting circuit unit 73 is disposed at the center. Yes. The translucent part 100 is attached to the upper end (one end 81) of the outer reflecting member 80, and the upper surface is the light emitting surface 101. In the lighting circuit unit 73, various circuit components 71 are mounted on a circuit board 72, and various circuit components 7
1 and the circuit board 72 are covered with a dome-shaped inner mirror member 74. Here, the inner surface of the outer reflecting member 80 and the outer surface of the inner reflecting member 74 are a mirror surface 80a and a mirror surface 74a, respectively.

  The heat radiating portion 90 has one end 91 in contact with the insulating plate 83 and the other end 92 connected to the base portion 87 through an insulating tube 96. The heat radiating portion 90 has a through hole 111 in the center, and a lead wire 84 is disposed in the through hole 111. The base part 87 includes a one-pole terminal 85 and another terminal 86.

  In the LED bulb 70, the light emitted from the white LED 75 and reflected by the mirror surface 80a and the mirror surface 74a of the outer reflection member 80 and the inner reflection member 74 is radiated to the outside, and good light emission characteristics are obtained.

JP 2009-21082 A (FIG. 1)

  However, the LED bulb 70 shown in FIG. 7, in order to assemble the light emitting unit 78, the circuit board 72 on which the insulating plate 83, the light source unit 77, and various circuit components 71 are mounted on the heat radiating unit 90, the internal reflection member 74, The external reflection member 80 and the translucent part 100 must be laminated. That is, the LED light bulb 70 shown in FIG. 7 has a complicated structure and is difficult to assemble because there are many parts for assembling the light emitting portion 78.

  Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide an LED bulb that can ensure assemblability while preventing deterioration of light emission characteristics even when a large capacitor is arranged in a space in a light emitting section. Objective.

  In order to solve the above-described problems, an LED bulb according to the present invention includes an LED bulb having an LED as a light source and a globe on the top, and a circuit board having an electrode pattern on the top surface, and a plurality of LED light sources on the top surface of the circuit board. The only capacitor in a cylindrical shape and a surface-mount type electronic component are mounted, and the difference between the height of the electronic component from the circuit board and the height of the LED light source from the circuit board is within 2 mm. The LED light source is disposed in a peripheral portion of the circuit board, the capacitor stands upright in the center of the circuit board, the globe covers the circuit board, and a part of the light emitted from the LED light source Directly reaches the top of the globe, and another part of the light is reflected by the condenser and reaches the side of the globe.

  In the LED bulb of the present invention, on the upper surface of the circuit board, a plurality of LED light sources are mounted in the peripheral portion, a single capacitor is mounted in the center, and electronic components are mounted in other portions. Here, the capacitor is cylindrical and upright. The electronic component is a low surface mount type. A globe covers the upper surface of the circuit board together with these LED light sources, capacitors, and electronic components. Part of the light emitted from the LED light source reaches the top of the spherical globe in such a way that it cannot be displaced by the capacitor. Further, another part of the light emitted from the LED light source hits the capacitor so as not to be squeezed by a short electronic component, and is reflected there to reach the globe.

  The cathode of the LED string in which the LED elements included in the LED light source are connected in series is connected to one end of the capacitor via one diode, and the one end is connected to the anode of the LED string via another diode. May be.

  In order to solve the above-described problems, an LED bulb according to the present invention includes an LED bulb having an LED as a light source and a globe on the top, and a circuit board having an electrode pattern on the top surface, and a plurality of LED light sources on the top surface of the circuit board. A plurality of cylindrical capacitors of the same size and surface-mount type electronic components are mounted, and the difference between the height of the electronic components from the circuit board and the height of the LED light source from the circuit board is 2 mm. The LED light source is disposed at a peripheral portion of the circuit board, the capacitor stands upright at the center of the circuit board, and is evenly disposed around the central axis of the circuit board, and the globe is A part of the light that covers the circuit board and emits the LED light source directly reaches the top of the globe, and the other part of the light is reflected by the capacitor, and is a side surface of the globe. Wherein the reach.

  The side surface of the capacitor may include a reflecting member.

  As described above, in the LED light bulb of the present invention, the light emitted from the LED light source reaches the entire globe including the top without being “scratched” by other components. Furthermore, in the LED bulb of the present invention, an LED light source, a capacitor, and an electronic component are integrated on a circuit board. As a result, the LED bulb of the present invention can ensure assemblability while preventing deterioration of the light emission characteristics even when a large capacitor is arranged in the space in the light emitting part whose outer shape is determined by the globe.

It is a perspective view of the LED light bulb shown as 1st Embodiment of this invention. It is the top view and front view of a circuit board which are contained in the LED bulb shown in FIG. FIG. 2 is a circuit diagram of the LED bulb shown in FIG. 1. It is a circuit diagram of the LED light bulb shown as 2nd Embodiment of this invention. It is a perspective view of the circuit board contained in the LED bulb shown as 3rd Embodiment of this invention. It is a circuit diagram of the LED light bulb shown as 3rd Embodiment of this invention. It is a schematic principal part sectional drawing which shows the structure of the LED bulb shown as a prior art example.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS. In the description of the drawings, the same or equivalent elements will be denoted by the same reference numerals, and redundant description will be omitted. () Indicates the invention specific matters described in the claims.

(First embodiment)
An overview of an LED bulb 10 shown as a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a perspective view of the LED bulb 10. As shown in FIG. 1, the LED bulb 10 includes a light emitting unit 11, a case 18, and a base 19 having a globe 17 and an LED light source 12 as constituent elements. In FIG. 1, a part of the globe 17 is cut so that the inside of the globe 17 can be seen. In the LED bulb 10, the light emitting unit 11 is attached to the upper part of the case 18, while the base 19 is attached to the lower part of the case 18. In addition to the globe 17, the light emitting unit 11 includes an LED light source 12, a capacitor 13, a diode bridge 14 (electronic component), an IC 15 (electronic component), and a circuit board 16. The circuit board 16 is attached to the upper end of the case 18.

  Next, the relationship between the arrangement and size of the LED light source 12, the capacitor 13, the diode bridge 14 (electronic component), and the IC 15 (electronic component) will be described with reference to FIG. FIG. 2A is a plan view of the circuit board 16 included in the LED bulb 10, and FIG. 2B is a front view of the circuit board 16. 2A and 2B show a state in which components such as the LED light source 12 are mounted.

  As shown in FIGS. 2A and 2B, the LED light source 12, the capacitor 13, the diode bridge 14, and the IC 15 are mounted on the upper surface of the circuit board 16. The LED light source 12 is disposed on the periphery of the circuit board 16. The capacitor 13 is mounted upright in the center of the upper surface of the circuit board 16. The diode bridge 14 and the IC 15 are mounted on the upper surface of the circuit board 16 and not on the portion where the LED light source 12 or the capacitor 13 is mounted.

  The LED light source 12 has a planar size of about 3 mm × 3 mm and a height of about 1 mm. In the LED light source 12, a plurality of LED elements are mounted on a submount substrate (also referred to as an interposer), and the LED elements are connected in series and covered with a fluorescent resin. The diode bridge 14 and the IC 15 are of a surface mount type with a short height, are larger in plane size than the LED light source 12, and have a height of about several millimeters (2 to 3 mm). On the other hand, the capacitor 13 is an electrolytic capacitor having a withstand voltage of 400 V, a diameter of about 10 mm, and a height of about 12 mm. The capacitor 13 is also a surface mount type, and has a connection electrode on the bottom surface.

  The circuit board 16 has wiring electrodes (not shown) only on the upper surface. Also, a power supply lead soldered to the upper surface of the circuit board 16 is not shown. As the circuit board 16, it is preferable to use an Al substrate (a transparent insulating layer is formed on the upper surface of the substrate) or a white ceramic having good reflectivity and thermal conductivity. When using aluminum nitride with good thermal conductivity, apply a reflective material on the top surface.

  The circuit of the LED bulb 10 will be described with reference to FIG. FIG. 3 is a circuit diagram of the LED bulb 10. For convenience of explanation, a commercial AC power source 19a is added. As shown in FIG. 3, the commercial AC power supply 19a is connected to the input terminal of the diode bridge 14 composed of four diodes 14a, 14b, 14c, and 14d through a fuse 19b. The current output terminal (cathode side) of the diode bridge 14 is connected to the anode of the LED array 12a in which a plurality of LED elements 12b are connected in series. The LED element 12b is included in the LED light source 12 (see FIGS. 1 and 2), and is connected in series within the LED light source 12, and the LED light sources 12 are also connected in series, so that the circuit board 16 (FIG. 1, (See FIG. 2) One LED row 12a is formed as a whole. The capacitor 13 and the resistor 15e are connected in parallel with the LED row 12a. The current limiting circuit 15f includes a resistor 15a, a transistor 15b, an FET 15c, and a resistor 15d. In the current limiting circuit 15f, the drain of the FET 15c is a current input terminal, and the lower end of the resistor 15d is a current output terminal. The current input terminal and the current output terminal are connected to the cathode of the LED array 12a and the terminal (anode side) where the current of the diode bridge 14 returns, respectively. The IC 15 (see FIGS. 1 and 2) includes a resistor 15e and a current limiting circuit 15f, and further includes a temperature compensation circuit and an overvoltage prevention circuit not shown.

  In FIG. 3, nodes A and B correspond to the base 19 (see FIG. 1). The fuse 19b is mounted on a board (not shown) different from the circuit board 16 (see FIGS. 1 and 2) as a safety circuit. A surge protection circuit may be added to this other substrate. Nodes C and D are power supply terminals of the circuit board 16 not shown in FIGS.

In the circuit of the LED bulb 10 shown in FIG. 3, the threshold value of the LED array 12a is set to about the effective value of the commercial AC power source 19a. That is, when the effective value is 100V, the LED array 12a has about 33 stages of LED elements 12b having a forward drop of 3V connected in series. In the circuit shown in FIG. 3, the voltage output from the commercial AC power supply 19a (the voltage is an absolute value. Hereinafter, the voltage output from the commercial AC power supply 19a is expressed as an absolute value) is higher than the threshold value of the LED array 12a. During the period, a current flows from the diode bridge 14 to the LED string 12a. At this time, the upper limit of the current value is limited by the current limiting circuit 15f, and the capacitor 13 is charged. During a period when the voltage output from the commercial AC power supply 19a is lower than the threshold value of the LED string 12a, the capacitor 13 is discharged, and the LED string 12
A current flows through a, and the LED element 12b lights up. In this way, the LED bulb 10 has no non-lighting period and flicker and the like are reduced.

  In the LED bulb 10, the capacitor has a capacitance of 10 μF. The resistor 15e is for preventing electric charge from remaining in the capacitor 13 when the LED bulb 10 is turned off. The current limiting circuit 15f limits the upper limit current so that the voltage across the resistor 15d is maintained at 0.6V.

  As shown in FIGS. 1 and 2, in the LED bulb 10, on the upper surface of the circuit board 16, a plurality of LED light sources 12 are mounted on the periphery, a capacitor 13 is mounted on the center, and a diode bridge 14 and an IC 15 are mounted on the other portions. Yes. Here, the capacitor 13 is the only tall cylindrical part and stands upright in the center of the circuit board 16. The diode bridge 14 and the IC 15 are short surface-mounted types, and the height thereof is about 2 mm larger than the LED light source 12. The globe 17 is spherical and covers the upper surface of the circuit board 16 together with the LED light source 12, the capacitor 13, the diode bridge 14, and the IC 15.

  Electronic parts such as the diode bridge 14 and the IC 15 are mounted with a silicon chip on a metal lead and molded with resin so that a part of the lead is exposed. As a result, the height of these parts can be suppressed to about 3 mm or less. The LED light source 12 usually has a back height of about 1 mm, and the light distribution characteristic has directivity upward. For this reason, if an easily available LED light source 12 and an electronic component (diode bridge 14 and IC 15) that are easily available and have a height difference of 2 mm or less with respect to the LED light source 12 are arranged on the circuit board 16, the electronic component Does not significantly affect the light distribution characteristics of the LED light source 12. If the difference between the height of the electronic component from the circuit board and the height of the LED light source from the circuit board exceeds 2 mm, the shadow produced by the electronic component cannot be ignored.

  Part of the light emitted from the LED light source 12 reaches the top of the spherical globe 17 so as not to be displaced by the capacitor 13. That is, in the LED bulb 10, a sufficient gap is secured between the upper end of the capacitor 13 and the top of the globe so that a part of the light emitted from the LED light source 12 reaches the top of the globe 17 directly. Further, as described above, the other part of the light emitted from the LED light source 12 has directivity, and therefore is disposed on the side of the LED light source 12 and is a low profile that is slightly thicker (2 mm) than the LED light source 12. It hits the capacitor 13 without being displaced by the diode bridge 14 and the IC 15, and is reflected there to reach the side surface of the globe 17. Since the LED light source 12 has directivity upward, the influence of light hitting the diode bridge 14 and the IC 15 in the LED bulb 10 can be ignored.

  As described above, the LED light bulb 10 reaches the entire globe 17 without so-called “damage” in which the light emitted from the LED light source 12 is shaded by the components on the circuit board 16. Further, in the LED bulb 10, electronic components such as the LED light source 12 and the capacitor 13 are integrated with the circuit board 16. That is, when assembling the light emitting unit 11 of the LED bulb 10, it is only necessary to attach the circuit board 16 and the globe 17 to the case 18. As a result, the LED bulb 10 can ensure assemblability while preventing deterioration of the light emission characteristics even if the large capacitor 13 is arranged in the space inside the light emitting unit 11 whose outline is determined by the globe 17.

(Second Embodiment)
In the LED bulb 10 shown in FIGS. 1 to 3, the threshold value of the LED array 12a (see FIG. 3) is set to the effective value voltage of the commercial AC power supply 19a as described above. In this way, the number of LED elements 12b that must be connected in series increases, and the withstand voltage of the capacitor 13 increases. Therefore, as a second embodiment of the present invention, an LED bulb 20 that can reduce the number of LED elements connected in series and the withstand voltage of a capacitor by half will be described with reference to FIG.

  FIG. 4 is a circuit diagram of the LED bulb 20. For convenience of explanation, a commercial AC power source 19a is added. As shown in FIG. 4, the commercial AC power source 19a is connected to the input terminal of the diode bridge 14 composed of four diodes 14a, 14b, 14c, and 14d through a fuse 19b. The current output terminal (cathode side) of the diode bridge 14 is connected to the anode of the LED array 22a in which the LED elements 22b are connected in series. The relationship between the LED light source 22 (not shown), the LED element 22b, and the LED array 22a is equal to the relationship between the LED light source 12, the LED element 12b, and the LED array 22a of the LED bulb 10 described in FIG. The number of series stages and the number of series stages of the LED elements 12b are different.

  The cathode of the LED string 22a is connected to the current input terminal of the current limiting circuit 24f including the resistor 24a, the transistor 24b, the FET 24c, and the resistor 24d, and is connected to the left terminal of the capacitor 23 via the diode 26 (one diode). . The left terminal of the capacitor 23 is connected to the anode of the LED array 22a via a diode 27 (another diode). The right terminal of the capacitor 23 is connected to a current input terminal of a current limiting circuit 25f including a resistor 25a, a transistor 25b, an FET 25c, and a resistor 25d. The current output terminal of the current limiting circuit 24 f is connected to the terminal (anode side) where the current of the diode bridge 14 returns, and is connected to the right terminal of the capacitor 23 via the diode 28. The current output terminal of the current limiting circuit 25f is connected to the upper terminal of the resistor 24d included in the current limiting circuit 24f.

  The overview of the LED bulb 20 is not shown because it is substantially the same as the LED bulb 10 shown in FIG. That is, the LED bulb 20 also has a plurality of LED light sources 22 in the peripheral portion, a single capacitor 23 in the center, and a diode bridge 14 and diodes 26 to 28 in the other portions and a current limit on the upper surface of the circuit board 26 (not shown). An IC 25 (electronic component, not shown) including the circuits 24f and 25f is mounted. Here, the capacitor 23 is cylindrical and upright. The IC 25 is a low surface mount type. The globe 17 (see FIG. 1) covers the upper surface of the circuit board 26 together with the LED light source 22, the capacitor 23, the diode bridge 14, and the IC 25. The nodes A and B correspond to the base 19 (see FIG. 1), and the fuse 19b is mounted on a substrate (not shown) different from the circuit substrate 26 as a safety circuit. Nodes C and D are power supply terminals (not shown) of the circuit board 26.

  In the circuit of the LED bulb 20 shown in FIG. 4, the threshold value of the LED array 22a is set to be slightly larger than half of the effective value of the commercial AC power supply 19a. That is, when the effective value is 100V, the LED array 22a has about 20 stages of LED elements 22b whose forward drop is 3V connected in series. In a steady state, the voltage at the left terminal of the capacitor 23 fluctuates at a value equal to or higher than the threshold value of the LED array 22a.

  In the circuit shown in FIG. 4, the current output from the diode bridge 14 to the LED string 22a and the current limiting circuit 24f is a period in which the voltage output from the commercial AC power supply 19a is higher than the threshold value of the LED string 22a and lower than twice the threshold value. Flows. At this time, the upper limit of the current value is limited by the current limiting circuit 24f, and the left terminal of the capacitor 23 is in a floating state.

  In a period in which the voltage output from the commercial AC power supply 19a is higher than twice the threshold value of the LED string 22a, the diode bridge 14 passes through the LED string 22a, the diode 26, the capacitor 23, the current limiting circuit 25f, and the resistor 24d to the diode bridge 14. The returning current flows. At this time, the upper limit of the current value is limited by the current limiting circuit 25f, and the capacitor 23 is charged. At this time, the FET 24c in the current limiting circuit 24f is cut off.

In a period when the voltage output from the commercial AC power supply 19a is lower than the threshold value of the LED string 22a, the current returns from the left terminal of the capacitor 23 to the right terminal of the capacitor 23 via the diode 27, the LED string 22a, the current limiting circuit 24f and the diode 28. Flows. That is, the LED bulb 20 is lit even during a period in which the voltage output from the commercial AC power supply 19a is lower than the threshold value of the LED array 22a, so that the non-lighting period is eliminated and flicker is reduced.

  As described above, the LED bulb 20 can halve the number of LED elements 22 b in series and the withstand voltage of the capacitor 23 compared to the LED bulb 10. As a result, the LED bulb 20 can ensure assembly while preventing deterioration of the light emission characteristics, and can achieve cost reduction and downsizing.

(Third embodiment)
In the LED bulbs 10 and 20 shown in FIGS. 1 to 4, the large and only capacitors 13 and 23 are arranged upright in the center of the upper surface of the circuit boards 16 and 26 (not shown). However, a plurality of capacitors may be dispersed and a smaller capacitor than the capacitors 13 and 23 may be used. Accordingly, an LED bulb 30 in which three capacitors are arranged upright in the center of the upper surface of the circuit board will be described as a third embodiment of the present invention with reference to FIGS.

  FIG. 5 is a perspective view of a circuit board 36 a included in the LED bulb 30. As shown in FIG. 5, on the upper surface of the circuit board 36a, six LED light sources 32 (one does not appear in FIG. 5 because one is on the back side of the capacitor 33b) are mounted on the periphery, and the central portion Are mounted so that the three capacitors 33a, 33b, and 33c are evenly arranged in an upright state, and the diode bridge 14 (electronic component) is not mounted on the portion where the LED light source 32 or the capacitors 33a, 33b, and 33c are mounted. IC 35a (electronic component) is mounted.

  The overview of the LED bulb 30 is not shown because it is substantially the same as the LED bulb 10 shown in FIG. That is, when the circuit board 16 of the LED bulb 10 is replaced with the circuit board 36a, the LED bulb 30 is completed.

  The circuit board 36a has an electrode pattern only on the upper surface. The LED light source 32 is obtained by mounting a plurality of LED elements on a submount substrate and packaging them. The plurality of LED elements are connected in series. Capacitors 33a, 33b, and 33c have electrodes on the bottom surfaces, reflect the side surfaces, are cylindrical, and have the same size. The diode bridge 14 and the IC 35a are short surface-mounted electronic components whose height difference is within 2 mm from the height of the LED light source 32 (about 1 mm).

  FIG. 6 is a circuit diagram of the LED bulb 30. Similar to the LED bulbs 10 and 20 shown in FIGS. 3 and 4, the output of the commercial AC power supply 19 a is rectified by the diode bridge 14 to obtain electric power. In the LED bulb 30, the LED row is divided into three partial LED rows 32a, 32b, and 32c. Diodes 34, 35, and 36 are provided as anodes of the partial LED rows 32a, 32b, and 32c, and current limiting circuits 37f, 38f, and 39f are provided as cathodes. Is connected. Capacitors 33a, 33b, and 33c are connected in parallel with the partial LED rows 32a, 32b, and 32c.

  The partial LED rows 32a, 32b, and 32c are obtained by connecting LED elements 32d, 32e, and 32f included in the LED light source 32 (see FIG. 5) in series. The diodes 34 to 36 allow the discharge currents of the capacitors 33a, 33b, and 33c to flow only to the partial LED rows 32a, 32b, and 32c, respectively. Each of the current limiting circuits 37f, 38f, and 39f includes depletion type FETs 37a, 38a, and 39a, and resistors 37b, 38b, and 39b that control the drain current of the FETs 37a, 38a, and 39a while detecting the current.

  The diode bridge 14 does not supply power to the partial LED string 32a in a period in which the output (full-wave rectified waveform) is less than the threshold voltage of the partial LED string 32a. The voltage of the full-wave rectified waveform rises, and during the period when the voltage is equal to or higher than the threshold voltage of the partial LED string 32a and smaller than the sum of the threshold voltage of the partial LED string 32a and the threshold voltage of the partial LED string 32b, A current flows back to the diode bridge 14 via the LED string 32a and the current limiting circuit 37f.

  Further, the voltage of the full-wave rectified waveform rises, and the voltage is equal to or higher than the sum of the threshold voltage of the partial LED row 32a and the threshold voltage of the partial LED row 32b, and the threshold voltage of the partial LED row 32a and the threshold voltage of the partial LED row 32b In a period smaller than the sum of the threshold voltages of the partial LED string 32c, a current flows from the diode bridge 14 to the diode bridge 14 via the partial LED strings 32a and 32b and the current limiting circuit 38f. At this time, the FET 37a included in the current limiting circuit 37f is cut off.

  Further, the voltage of the full-wave rectified waveform rises, and during the period when the voltage is equal to or higher than the sum of the threshold voltage of the partial LED string 32a, the threshold voltage of the partial LED string 32b, and the threshold voltage of the partial LED string 32c, A current flows back to the diode bridge 14 through the LED strings 32a, 32b, and 32c and the current limiting circuit 39f. At this time, the FETs 37a and 38a included in the current limiting circuits 37f and 38f are cut off.

  The reverse process is followed during the period when the voltage of the full-wave rectified waveform drops.

  The capacitors 33a, 33b, and 33c are charged during a period in which current flows from the diode bridge 14 to the partial LED rows 32a, 32b, and 32c. When no current flows from the diode bridge 14 into the partial LED strings 32a, 32b, 32c, the capacitors 33a, 33b, 33c start discharging, and the partial LED strings 32a, 32b, 32c are lit by this discharge current.

  Since only the voltage about the threshold voltage of the partial LED rows 32a, 32b, 32c is applied to the capacitors 33a, 33b, 33c, the withstand voltage of the capacitors 33a, 33b, 33c can be lowered. Therefore, the capacitors 33a, 33b, and 33c can be reduced in size compared to the capacitor 13 included in the LED bulb 10 shown in FIG. As a result, the LED bulb 30 can ensure assemblability while preventing deterioration of the light emission characteristics, and can lower the top of the globe 17 (see FIG. 1).

10, 20, 30 ... LED bulbs,
11 ... light emitting part,
12, 22, 32 ... LED light source,
12a, 22a, 32a, 32b, 32c ... LED row,
12b, 22b, 32d, 32e, 32f ... LED elements,
13, 23, 33a, 33b, 33c ... capacitors,
14 ... Diode bridge (electronic component),
14a, 14b, 14c, 14d, 26-28, 34-36 ... diodes,
15, 25, 35a ... IC (electronic component),
15a, 15b, 15e, 24a, 24d, 25a, 25d,
37b, 38b, 39b ... resistance,
15b, 24b, 25b ... transistors,
15c, 24c, 25c, 37a, 38a, 39a ... FET,
15f, 24f, 25f, 37f, 38f, 39f ... current limiting circuit,
16, 26, 36a ... circuit board,
17 ... Glove,
18 ... Case,
19 ...
19a ... commercial AC power supply,
19b ... fuse.

Claims (4)

In an LED bulb having an LED as a light source and a globe on the top,
A circuit board having an electrode pattern on the upper surface,
On the upper surface of the circuit board, a plurality of LED light sources, a single cylindrical capacitor, and a surface-mount electronic component are mounted,
The difference between the height of the electronic component from the circuit board and the height of the LED light source from the circuit board is within 2 mm,
The LED light source is disposed on the periphery of the circuit board,
The capacitor stands upright in the center of the circuit board,
The globe covers the upper surface of the circuit board,
A part of the light emitted from the LED light source directly reaches the top of the globe, and the other part of the light is reflected by the capacitor and reaches the side surface of the globe. .   The cathode of the LED string in which the LED elements included in the LED light source are connected in series is connected to one end of the capacitor via one diode, and the one end is connected to the anode of the LED string via another diode. The LED bulb according to claim 1, wherein In an LED bulb having an LED as a light source and a globe on the top,
A circuit board having an electrode pattern on the upper surface,
On the upper surface of the circuit board, a plurality of LED light sources, a plurality of cylindrical capacitors of the same size, and a surface mount type electronic component are mounted,
The difference between the height of the electronic component from the circuit board and the height of the LED light source from the circuit board is within 2 mm, and the LED light source is disposed in the peripheral portion of the circuit board,
The capacitor stands upright at the center of the upper surface of the circuit board and is evenly arranged around the central axis of the circuit board,
The globe covers the circuit board,
Part of the light emitted from the LED light source directly reaches the top of the globe, and the other part of the light is reflected by the capacitor and reaches the side of the globe.   The LED bulb according to any one of claims 1 to 3, wherein a side surface of the capacitor includes a reflecting member.