K.P. Cheung, Department of Architecture, The University of Hong Kong
This page started in March 2000

Daylight Collector - Himawari

 
"Himawari" is a device consists of a sun sensor and Fresnel lens to collect and direct sunlight through optical fiber to the designated position. A stepper motor is used and is controlled by a sensor and a microprocessor to point its lenses in the direction of the sun at all times. When there is no direct sunlight, the "HIMAWAEI" system tracks the sun accurately along the computed arc of the sun. 

 

Also, "HIMAWARI" cuts out most of the ultra-violet and infra-red radiation. When sunlight passes through the Fresnel lenses, chromatic aberration occurs, causing different wavelength of sunlight, (ultra-violet, visible, and infra-red radiation) to focus at different distances from the lens. By placing the input end of the optical fiber at the focal point of visible light rays, most of the ultra-violet and infra-red radiation can be eliminated.

Different types of "Himawari" ( Dimensions for different types of "Himawari" )

  No. of lens Size of lens Area that light up (cm2) Diameter of the dome Height Weight     Electricity needed Electricity used
198 95 14,035 1,630 2,500 628 33 53,790 AC 100 V 1A 15W
90 95 6,379 1,170 2,045 346 15 24,450 AC 100 V 1A 12W
36 95 2,552 1,000 1,475 88 6 9,780 AC 100 V 1A 5W
12 95 851

520

 810 14 2 3,260 AC 100 V 1A 2W
6 95 425 420 590 9.4 1 1,630 AC 100 V 1A 2W
36 95 2,552 1,000 1,475 90 6 9,780 - -
12 95 851 520 810 15 2 3,260 - -
6 95 425 420 590 10 1 1,630 - -

Some examples in using "HIMAWARI":

Internal Sunlight:  For indoor plants; Aquarium; Indoor sunbath
Residential usage: Living room; Kitchen; Rooms that face North or basement; Courtyard
Commercial usage: Office; lift lobby; Spot light for features; Display area; Atrium
Underground Communal Facilities: Underground shopping area; Area under the road; Elderly center; Theater (spot light)
Special environment: Atomic Power Plant; Lighting inside water; Sensory testing; 
Devices for terminal lighting

Reference website: http://www.himawari-net.co.jp/e_home.html