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Patent Issued for LED Light Source Lamp Having Drive Circuit Arranged in Outer Periphery of LED Light Source

May 14, 2014



By a News Reporter-Staff News Editor at Journal of Engineering -- From Alexandria, Virginia, VerticalNews journalists report that a patent by the inventors Nakagawa, Hiroki (Osaka, JP); Namura, Toshiyuki (Osaka, JP); Kakuno, Yoshinori (Osaka, JP); Sugita, Kazushige (Hyogo, JP), filed on November 18, 2013, was published online on April 29, 2014.

The patent's assignee for patent number 8710724 is Panasonic Corporation (Osaka, JP).

News editors obtained the following quote from the background information supplied by the inventors: "In recent years, in association with improvement of semiconductor technologies, there are enhanced demands for LED light source lamps that use solid-state light emitting elements.

"The above LED light source lamps cause less power consumption, have long life, and thus greatly contribute to promotion of energy conservation. Therefore, it is expected that such LED light source lamps will explosively prevail in the future.

"Here, Patent Literature 1 discloses a conventional thin LED lamp that has a built-in drive circuit.

"Meanwhile, there also are great demands for good illumination where an even brightness is realized on the light-emitting surface. However, the area of a light-emitting surface of a solid-state light emitting element is smaller than that of a fluorescent tube or the like, and unevenness of the brightness on the light-emitting surface tends to occur. Therefore, in order to reduce the unevenness, in a general LED light source lamp, a diffusion film is arranged to a side toward which light is emitted from the solid-state light emitting element.

"Further, in order to reduce the unevenness of the brightness on the light-emitting surface, and to make the brightness on the light-emitting surface more even, means such as a thicker diffusion film or a higher particle density in a diffusion film may be employed."

As a supplement to the background information on this patent, VerticalNews correspondents also obtained the inventors' summary information for this patent: "Problems to be Solved by the Invention

"However, the more even the brightness on the light-emitting surface is made, the more the light extraction efficiency is reduced, resulting in lower brightness. Thus, there is a demand for obtaining a light-emitting surface having more even brightness, without deteriorating the light extraction efficiency. Further, in the thin LED lamp as in Patent Literature 1, in addition to the fact that the LED lamp is thin, a metal core substrate 6 for mounting a driver circuit and a metal block 7 are arranged on the rear side of an LED 3. Therefore, the distance between the LED 3 and a light-emitting surface covering case 5 (corresponding to the above diffusion film) can hardly be secured. When the distance between the LED and the diffusion film is extremely short as in this case, the effect of the reduced unevenness of the brightness brought by the diffusion film is reduced, the unevenness of the brightness on the light-emitting surface becomes distinctive. Thus, by only using a thicker diffusion film or an increased particle density, it is difficult to make the brightness on the light-emitting surface even.

"Moreover, in order to maintain a stable drive condition, there is a demand for further increasing heat dissipation performance.

"Therefore, a first object of the present invention is to provide an LED light source lamp that can yield more even light-emitting surface without deteriorating the light extraction efficiency, and a second object of the present invention is to provide an LED light source lamp that can further improve the heat dissipation performance.

"Solution to the Problems

"The present invention is directed to an LED light source lamp. In order to solve the above problems, the LED light source lamp of the present invention is an LED light source lamp including a built-in drive circuit in a housing thereof and configured to be used by being attached to a lamp holder, the LED light source lamp including: an LED installation plate; an LED module; and a light diffusion member. The LED installation plate is arranged, in a main space in the housing, on an attachment side to the lamp holder. The LED module is installed on a surface, of the LED installation plate, opposite to the lamp holder, and includes at least one LED element that emits light by being driven by the drive circuit. The light diffusion member is arranged so as to block an optical axis of light emitted by each of the at least one LED of the LED module. The drive circuit is arranged in an outer peripheral space, between the LED module and the light diffusion member, so as not to block the optical axis of light emitted by each of the at least one LED of the LED module.

"Further, the LED light source lamp may include a separation member configured to separate the drive circuit from a space between the LED module and the light diffusion member to shield thermal radiation from the LED module, and configured to reflect and direct some of light, emitted from the LED module, that does not directly reach the light diffusion member, toward the light diffusion member.

"Further, the LED light source lamp may include a reflection diffusion member arranged between the LED module and the light diffusion member so as to block some of the optical axis emitted by each of the at least one LED of the LED module, and configured to reflect and diffuse some of light emitted from the LED module.

"Further, in the LED light source lamp, the drive circuit may be arranged in the outer peripheral space, divided in two positions distanced from each other, and may include a primary side power source circuit located at one of the two positions, and a switching transistor located at the other position.

"Further, in the LED light source lamp, the LED installation plate may have a rear surface, of the surface on which the LED module is installed, serving as an attachment surface to the lamp holder, and may form a part of the housing.

"Further, in the LED light source lamp, the LED installation plate may have a higher thermal conductivity than a member around the attachment surface to the lamp holder.

"Further, in the LED light source lamp, when the LED light source lamp is attached to the lamp holder, the LED installation plate may closely contact a thermal conductive member of the lamp holder.

"Further, in the LED light source lamp, the drive circuit may further include a power input terminal installed on an area where the LED installation plate is not arranged, and configured to be connected to an external power line when the LED light source lamp is attached to the lamp holder, and the LED installation plate is preferably not connected to an external power line when the LED light source lamp is attached to the lamp holder.

"Advantageous Effects of the Invention

"As described above, in the present invention, it is possible to secure, to a maximum extent, the distance between the LED module and the light diffusion member in a limited space. Therefore, it is possible to make the brightness at the light diffusion member more even, without hardly any deterioration of the light extraction efficiency.

"Further, by the provision of the separation member, it is possible to improve the brightness and make the brightness more even while thermally protecting the drive circuit.

"Further, by the provision of the reflection diffusion member, the brightness can be made more even.

"Further, by arranging the drive circuit, divided in different positions, electromagnetic induction coupling can be prevented and a noise can be reduced.

"Further, since the drive circuit is not located nearer to a lamp holder relative to the LED module, the LED installation plate can be externally exposed.

"Further, the LED installation plate has a high thermal conductivity and closely contacts the thermal conductive member of the lamp holder, and thus, heat can be easily dissipated to the exterior via the lamp holder."

For additional information on this patent, see: Nakagawa, Hiroki; Namura, Toshiyuki; Kakuno, Yoshinori; Sugita, Kazushige. LED Light Source Lamp Having Drive Circuit Arranged in Outer Periphery of LED Light Source. U.S. Patent Number 8710724, filed November 18, 2013, and published online on April 29, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=70&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=3495&f=G&l=50&co1=AND&d=PTXT&s1=20140429.PD.&OS=ISD/20140429&RS=ISD/20140429

Keywords for this news article include: Panasonic Corporation.

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Source: Journal of Engineering


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