Sun tracking lighting device

Details Sun tracking lighting device Sun tracking lighting device

2003-07-22

2004-10-05

Mahoney, Christopher (Department: 2851)

Optical: systems and elements

Building interior illumination with reflected, refracted or...

With reflection

Reexamination Certificate

active

06801361

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to light admitting devices of the sun tracking type, and more particularly to a light admitting device of the type mentioned which has mounted thereon a solar cell panel for charging the power source for driving light reflecting means.
BACKGROUND ART
Light admitting devices are adapted for use with a skylight bore having an opening in the roof of a building and extending to the ceiling for admitting sunlight into the interior of the building where sunlight is not available. The device has light reflecting means, which is provided at the upper end of the skylight bore for reflecting sunlight into the interior through the bore.
Light admitting devices of the sun tracking type are known (as disclosed, for example, in U.S. Pat. No. 5,999,323) which comprise light reflecting means directed toward the sun and made rotatable to track the sun so as to achieve an improved light admission efficiency since the sun changes in direction with time.
With the light admitting device of the sun tracking type, the light reflecting means is rotated by a motor as a drive source. The motor is so controlled that the reflecting means is thereby rotated to track the sun during the daylight hours from sunrise till sunset, and is further rotated after sunset and directed toward the position of sunrise on the next day to complete one turn of rotation.
Power source means available for the motor include a commercial power source and secondary cell which is rechargeable by a solar cell, whereas the commercial power source requires interior wiring and is cumbersome to install. Power source means which are rechargeable by the solar cell are therefore desirable.
However, the conventional light admitting device has the problem that the solar cell panel can not always be fully exposed to sunlight depending on the position of the sun to exhibit a reduced power generation efficiency, because the solar cell panel, which needs to be electrically connected to the motor, is attached to a mount frame to which the motor is fixed. Thus, there is a need to use a solar cell panel of increased size to compensate for insufficient power generation.
At sunrise or sunset or during winter, the sun is at a low altitude, and sunlight is therefore incident on the light admitting device at a low angle. At this time, the sunlight is almost entirely reflected from the front side of the light reflecting means which is closer to the sun, consequently permitting light to enter the skylight bore at one portion only.
Many members including a mount rod, bracket and motor are provided under the light reflecting means. Accordingly, the sunlight reflected from the light reflecting means is blocked by these members, failing to reach the skylight bore effectively and entailing the problem of a lower light admission efficiency.
The light admitting device has angle detecting means such as a potentiometer for detecting the angle of rotation of the light reflecting means. The angle detecting means must be installed accurately in position with respect to angle. However, since the orientation of the skylight bore differs with the direction toward which the building faces, it is conventional practice to orient the reflecting means and the potentiometer in the same direction as the skylight bore first and to thereafter install the device. Consequently, it is difficult to adjust the orientation after installation.
An object of the present invention is to provide a light admitting device of the sun tracking type wherein a solar cell is mounted on the same support member as the light reflecting means which tracks the sun to thereby enable the solar cell to achieve an improved power generation efficiency without making the device greater in size and complex.
Another object of the invention is to provide a light admitting device of the sun tracking type which is adapted to admit a sufficient quantity of light at sunrise or sunset or during winter when the sun is at a low altitude.
Still another object of the invention is to provide a light admitting device of the sun tracking type wherein means for detecting the angle of the light reflecting means can be adjusted in conformity with the orientation of the skylight bore at the time of installation.
DISCLOSURE OF THE INVENTION
The present invention provides a light admitting device
10
of the sun tracking type which comprises a dome
20
made of a light transmitting material, light reflecting means
30
rotatably supported within the dome
20
for reflecting sunlight, drive means
60
coupled to the light reflecting means
30
for orienting the light reflecting means
30
toward the direction of the sun by rotation, rechargeable power source means
43
electrically connected to the drive means
60
for supplying electric power to the drive means
60
, and a solar cell panel
40
electrically connected to the power source means
43
for charging the power source means
43
, wherein the solar cell panel
40
is disposed within the dome
20
so as to be rotatable with the light reflecting means
30
. Since the solar cell panel
40
rotates with the slight reflecting means
30
moving to track the sun, the solar cell panel
40
can be exposed to sunlight with an improved efficiency to achieve a higher power generation efficiency. The solar cell panel
40
requires no drive unit for controlling the orientation and can therefore be compacted and made lightweight. Since the solar cell panel
40
is disposed within the dome
20
, the means for ensuring water-tightness for the panel
40
can be dispensed with.
Preferably, the drive means
60
has a hollow rotating shaft
66
, and wiring
46
for electrically connecting the solar cell panel
40
to the power source means
43
extends through the rotating shaft
66
, the light reflecting means
30
being connected to one end of the rotating shaft
66
. The solar cell panel
40
is electrically connected to the power source means
43
by the wiring
46
extending through the rotating shaft
66
. The wiring
46
is accordingly unlikely to become caught, for example, by the light reflecting means
30
, which in turn is rotatable free of any interference. The wiring
46
, which is enclosed in the rotating shaft
66
, will not deteriorate owing to exposure to sunlight.
Preferably, the drive means
60
is provided at the top of the dome
20
, and the light reflecting means
30
is suspended from and supported by the rotating shaft
66
of the drive means
60
. With the light reflecting means
30
supported in suspension, the drive torque required for rotating the reflecting means
30
can be diminished. This reduces the power consumption of the drive means
60
, serving to render the power source means
43
and the solar cell panel
40
compact and lightweight.
Preferably, the drive means
60
rotates the light reflecting means
30
to orient the reflecting means
30
toward the direction of the sun during the daylight hours and reversely rotates the reflecting means
30
after sunset to move the reflecting means
30
to the position of sunrise of the following day.
Instead of rotating the reflecting means
30
one turn a day, the reflecting means
30
is reversely rotated and moved after sunset to the position of sunrise of the next day. This obviates the likelihood that the wiring electrically connecting the solar cell panel
40
to the power source means
43
will be twisted.
Preferably, the light admitting device
10
of the sun tracking type according to the invention comprises a casing
50
a
fixedly provided within the dome
20
and housing the drive means
60
and the power source means
43
therein, the drive means
60
and the power source means
43
being made rotatable together within the casing
50
a
to constitute a control unit
51
, the light reflecting means
30
and the solar cell panel
40
being coupled to the control unit
51
and rotatable with the control unit
51
. The drive means
60
and the power source means
43
are made rotatable together as a control unit, and the control unit
51
and the sol

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