A lighting device using an LED element as a light source begins to spread. In some bulb-shaped LED lamps of the LED lighting devices, an optical member, such as a reflector and a prism, is arranged within the globe in order to widen the light distribution (e.g., Patent Document 1). Further, in some bulb-shaped LED lamps, the number of elements that block light from a light emitting part is reduced by arranging the light emitting part in the vicinity of the center of the globe (e.g., Patent Documents 2 and 3). Furthermore, in some bulb-shaped LED lamps, a large number of LED devices are arranged three-dimensionally within the globe (e.g., Patent Documents 4 and 5). In the following explanation, an LED element cut from a wafer is referred to as an LED die, an LED element in which the LED die is coated with a fluorescent resin and electrodes for mounting are formed is referred to as an LED device, and a constituent part in which the LED device is mounted on a mounting substrate is referred to as an LED module.
FIG. 1 of Patent Document 1 illustrates a beacon light A (LED lamp) including a plurality of LED lamps 2 (LED devices) and a substantially funnel-shaped light control member 3 inside a globe 5. The outer surface 31 of the light control member 3 is a reflector, which bends light from the LED lamps 2 arranged on the periphery of a base material 1 substantially by right angles. The center part of the light control member 3 is hollow and allows light from the LED lamp 2 arranged at the center part of the base material 1 to pass straight as it is. As described above, the beacon light A radiates light within a desired range of angle.
Recently, the size of an LED die has increased and the current tolerance has also become large. Because of this, an LED lamp which is bright and has wide light distribution may be obtained by arranging a single or a few LED dies in the center of the globe. For example, FIG. 1 of Patent Document 2 illustrates a super-wide light distribution type LED lamp in which part of a metal frame 1 is provided with a raised part 1A and on the raised part 1A, an LED chip 3 (LED die) is mounted. In the super-wide light distribution type LED lamp, the LED chip 3 is arranged in the vicinity of the center of a translucent plastic cover 6 and the wide light distribution characteristic is obtained.
FIG. 2 of Patent Document 3 illustrates a light emitting module 64 (LED lamp) including three light emitting element chips 20 (LED die) at the center part of a translucent core body 65 (globe). The light emitting element chips 20 are connected to lead parts 31 and lead parts 33 by silver paste. The lead parts 31 and the lead parts 33 are fixed to a terminal mold part 161. The surroundings of the light emitting element chips 20, the lead parts 31, and the lead parts 33 are enveloped with a liquid mold medium 30. The liquid mold medium 30 diffuses heat produced by the light emitting element chips 20 into the surroundings by convection by being in direct contact with the light emitting element chips 20. The liquid mold medium 30 is accommodated and sealed within the translucent core body 65 together with the light emitting element chips 20.
As another technique for obtaining an LED lamp which is bright and has wide light distribution, there is a technique in which a large number of LEDs are arranged three-dimensionally within a globe. For example, FIG. 1 of Patent Document 4 illustrates an LED bulb (LED lamp) including a large number of LED chips 6 (LED device) on a FPC (flexible printed circuit) uniformly arranged in the shape of a basket within a cover 2 (globe). This LED bulb includes a globular light source and radiates direct light of the LED chips 6 in a variety of directions, which makes it possible to radiate light in all directions.
FIG. 1 of Patent Document 5 illustrates a bulb-shaped LED luminaire 1 in which a large number of chip LEDs 10 (LED device) are arranged on the top surface and side surfaces of a substrate structure 5 having a multi-surface structure within a transparent cover 4 (globe). In the bulb-shaped LED luminaire 1, an electrically conductive material is applied to side substrates 6 and a ceiling plate 7 included in the substrate structure 5, and materials excellent in thermal conductivity are used as the plate materials, and thereby heat dissipation efficiency is improved.