ROHM has developed LEDs for lighting utilizing a well-established in-house production system, along with extensive expertise gleaned from fifty years as a market leader in semiconductor products. This allows us to create semiconductor-based lighting devices and components optimized to user needs for form, function, and quality.
We have been developing LEDs since 1973 and are actively implementing research and development from the element composition stage. Our production volume of 5 billion units annually is among the largest in the industry.
Our power ICs, including LED drivers, feature the industry's highest conversion efficiency along with high-performance functions such as precision dimming, making them ideal for lighting applications.
We have developed AC/DC and DC/DC converter modules that minimize both standby and operating power consumption. Our experience as a system IC manufacturer enables the creation of compact multifunction power modules that reduce environmental impact.
Our experience in developing and manufacturing discrete components ? the backbone of most electronic circuitry - extends as far back as 50 years. ROHM components are renowned for their quality and reliability in a variety of fields.
In order to increase the effectiveness of LED lighting devices we have worked on optimizing light
distribution, mainly through LED configuration and the use of reflectors.
Figure 1: LED configuration: Surface illumination
ROHM's LED Downlights widen the angle of light emission and minimize glare through a combination of surface light emission using multiple low-power LEDs and parabolic reflectors. The result is uniform, effective light distribution.
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Figure 2: LED mounting position recessed
by making the AI heat sink smaller
In order to achieve the same brightness as fluorescent lamps we designed a fixture that allows for the necessary vertical and horizontal brightness levels. Through innovations in LED mounting position and the material selection and from the use of diffusion/reflection plates, we have developed a unique structure that mimics the effects of fluorescent lighting.
Figure 3: Brightness distribution (LED light bulbs)
The three-dimensional arrangement results in radial light distribution equivalent to conventional incandescent and pendant lamps.
Colored lighting has a significant effect on both the effectiveness and presentation.
ROHM offers high color rendering LEDs and lighting solutions to fit virtually any requirement.
Figure 4: Structural comparison: Single-chip LED vs. Multi-chip LED
A single chip produces unwanted color separation, both internally and externally. Arranging multiple chips together causes the external light to mix with the light of neighboring chips, resulting in little color separation. Also, color separation generated when passing through lenses can be eliminated by adjusting the light emission strength of blue and yellow.
Graph 1. Color rendering wavelength distribution:
Conventional white LED vs. ROHM high color-rendering white LED
Conventional methods for creating white involve adding yellow phosphors to blue LEDs. In contrast, ROHM's unique technology adds green and red phosphors to blue LEDs, increasing color rendering characteristics by approximately 20%, to a color rendering index of Ra95. This is equivalent to a CIE rank of 1A, the highest, making them suitable for use in art museums and for color testing.
Graph 2. Color rendering index: Conventional white LED vs. ROHM high color-rendering white LED