JP2002100219A - Sun-tracking-type sunbeam-gathering apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sun-tracking-type sunbeam-gathering apparatus which can gather sunbeam sufficiently even when the altitude of the sun is low, such as at sunrise, at sunset and in winter. SOLUTION: The sun-tracking-type sunbeam-gathering apparatus has a dome 20 made of light-transmitting material, a light reflecting means 30 positioned within the dome 20 and reflects sunbeam, and a drive means 60 which rotates the light reflecting means 30 such that the direction of the light reflecting means follow the direction of the sun. The light reflecting means 30 has plural reflecting panels 31, 32 and 33. The reflecting panels are arranged in certain spacing so that the faces of the adjacent reflecting panels face each other. The bottom end of the front reflecting panel 31, which is the nearest to the sun, is located higher than the bottom ends of the rear reflecting panels 32 and 33 with respect to the horizontal plane.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sun-tracking type daylighting device, and more particularly, to a sun-tracking type daylighting device equipped with a solar cell panel as a driving power source.

[0002]

2. Description of the Related Art In order to take sunlight into a room where sunlight does not reach, a lighting hole penetrating from a roof of a building to a ceiling is opened, and a light reflecting means is provided at an upper end of the lighting hole to reflect light. There is a daylighting device that guides sunlight that strikes the means to the interior through a daylighting hole. Since the direction of the sun changes with time, it is necessary to rotate the light reflecting means in accordance with the direction of the sun in order to perform daylighting efficiently.

Therefore, there is a daylighting device in which a light-transmitting dome is formed at the upper end of a daylighting hole, and a plurality of light reflecting means rotated by a motor are arranged in the dome. The motor is disposed at the center of a bracket that is hung over the upper end of the lighting hole. At the tip of the rotation shaft of the motor, a light reflecting means mounting rod is horizontally mounted. Are fixed at a predetermined angle (for example, U.S. Pat.
issue). When the motor is driven, the light reflecting means rotates together with the mounting rod. By controlling the motor so that the direction of the light reflecting means follows the direction of the sun, the sunlight reflected by the light reflecting means is guided indoors through the lighting hole.

[0004]

At sunrise, sunset, and winter when the solar altitude is low, sunlight enters the lighting device at a low angle. Therefore, most of the sunlight is reflected by the light reflecting means on the front side close to the sun, so that the light entering the lighting hole may be biased to one place. Further, in the above-described daylighting device, a number of members such as a mounting rod, a bracket, and a motor are provided below the light reflecting means. For this reason, a part of the sunlight reflected by the light reflecting means is blocked by these members and does not reach the lighting hole, so that the lighting efficiency is reduced.

SUMMARY OF THE INVENTION An object of the present invention is to provide a sun-tracking type daylighting device capable of sufficiently daylighting particularly at sunrise, sunset, and winter when the sun altitude is low.

[0006]

According to the present invention, there is provided a sun tracking type daylighting apparatus according to claim 1 of the present invention.
Is a dome (20) formed of a translucent material, and the dome (2
(0), a light reflecting means (30) for reflecting sunlight,
A driving means (60) for rotating the direction of the light reflecting means (30) in accordance with the direction of the sun, and a sun tracking type daylighting device including 32) (33)
Are arranged at predetermined intervals so that the surfaces of adjacent reflective panels face each other, and the front reflective panel (31) close to the sun is compared with the rear reflective panels (32) (33). hand,
The lower end was higher than the horizontal plane.

Further, in the sun tracking type daylighting device (10) according to the second aspect of the present invention, the front reflecting panel (31) is arranged such that the upper end thereof is in a horizontal plane more than the rear reflecting panels (32) and (33). To lower.

According to a third aspect of the present invention, in the sun tracking type daylighting device (10), the reflection panels (31), (32), and (33) are provided to be inclined with respect to a horizontal plane, and the front reflection panel ( 31) has a smaller inclination angle θ than the rear reflective panels (32) and (33).

According to a fourth aspect of the present invention, in the sun tracking type daylighting device (10), the driving means (60) is installed on the top of the dome (20), and the light reflecting means (30) is driven by the driving means (60). ).

[0010]

The sun-tracking type daylighting device (10) according to the first aspect of the present invention is configured such that the lower end of the front reflection panel (31) close to the sun is connected to the rear reflection panels (32) (33). On the other hand, because it is configured to be higher than the horizontal plane, when the penetration angle of sunlight is small, the sunlight not only reflects on the front reflective panel (31) and enters the lighting hole (90), but also Some of the sunlight directly enters the lighting hole (90). Therefore, the light that enters the lighting hole (90) is not deviated to one place, and sufficient lighting performance can be secured even at low sun altitudes at sunrise, sunset, and winter.

In the sun tracking type daylighting device (10) according to the second aspect of the present invention, the upper end of the front reflection panel (31) close to the sun is compared with the rear reflection panels (32) and (33). Because it is configured lower than the horizontal plane, when the angle of penetration of sunlight is small, not only the front reflective panel (31) but also the rear reflective panels (32) and (33) are exposed to sunlight. . Therefore, the lighting hole
Sufficient light can be guided to (90), and sufficient lighting performance can be secured even at low sun altitudes at sunrise, sunset, and winter.

A sun tracking type daylighting device (10) according to a third aspect of the present invention is configured such that a front reflection panel (31) close to the sun is tilted lower than rear reflection panels (32) and (33). Therefore, sunlight with a small angle of penetration is reflected on the front reflective panel (31).
Accordingly, the light can be refracted and reflected at an angle close to the vertical, and more light can be guided to the lighting hole (90).

A sun tracking type daylighting device (10) according to a fourth aspect of the present invention suspends and supports the light reflecting means (30), and the driving means (60) and the like are provided with the light reflecting means (30). Since it is not on the lower side, the sunlight irradiated on the light reflecting means (30) is efficiently guided to the lighting hole (90) almost without being blocked.

[0014]

1 to 3 show a sun tracking type daylighting device (10) according to the present invention. In the following, the light reflection means (3
0) will be described below, but the present invention is not limited to the suspension-supporting type, and it is needless to say that the present invention can also be applied to a stationary-type daylighting device that supports the lower part of the light reflecting means. . 2 and 3, the direction of the sun S is defined as "front" and the opposite side is defined as "rear".

As shown in FIG. 2, the sun tracking type daylighting device (10) is installed at the upper end of a daylighting hole (90) opened from the roof of the building to the ceiling. The lighting hole (90) has an upper end opening at the roof of the building. The daylighting hole (90) is generally formed in a square having a side of about 120 cm, and its direction varies depending on conditions such as the size, structure, orientation, and required amount of light of a building or a room. Inner surface (92) of lighting hole (90)
Is mirror-finished to efficiently guide the light reflected by the sun-tracking type daylighting device indoors. The lighting hole (9
A transparent indoor light distribution plate (not shown) for diffusing the light entering the room through the lighting hole (90) is attached to the lower end of (0) (the indoor ceiling side).

The sun tracking type daylighting device (10) is shown in FIGS.
As shown in the figure, a dome (20) made of a translucent material attached to the upper end of the lighting hole (90), light reflecting means (30) suspended and supported in the dome, and light reflecting means (30) And a control box (50) for rotating the camera following the direction of the sun. Hereinafter, each component will be described in detail.

<Dome (20)> As shown in FIGS. 1 to 4, the dome (20) protects the light reflecting means (30) from wind, rain, dust, etc. This is a transparent or translucent cover that prevents The dome (20) can be formed, for example, by molding a transparent acrylic resin plate or a polycarbonate resin plate having a thickness of about 3 to 5 mm, or by processing hard glass, hard plastic, or the like. The dome shown
In (20), the center is processed into a substantially hemispherical shape, and the periphery is a lighting hole (9
This is an acrylic resin formed into a square according to the shape of (0). The dome (20) is not limited to a hemispherical shape, but may have various shapes such as a square shape and a conical shape, and may be reinforced with a frame if necessary. At the center of the top of the dome (20), as shown in FIG. 4, a mounting hole (22) for mounting the control box (50) is opened, and around the mounting hole (22), the control box (50) is provided. ) Are screw holes (22a) formed at equal intervals.

<Light Reflecting Means (30)> The light reflecting means (30) is constituted by mounting a plurality of reflecting panels (31), (32), (33) on a support frame (34). It is suspended and supported.
The support frame (34) is located on the front side as shown in FIGS.
The (sun S side) is a downwardly inclined rod, and a hook (35) for suspending and supporting is protruded upward from the center slightly behind. The support frame (34) has three reflective panels
(31) (32) (33) are deployed. Each reflective panel (31) (32) (33)
Is a mirror body that reflects sunlight, and is made by, for example, attaching a resin film having a mirror surface formed by aluminum evaporation to a lightweight styrene resin plate. Reflective panel (31) (32) (3
3) is supported side by side on the front, center and rear sides of the support frame (34) such that the surfaces of the panels face each other.
Except for the rearmost reflective panel (33), even if the light reflected by the rear reflective panel hits the back of the front reflective panel, not only the front but also the front so that the light can be guided to the lighting hole (90). It is desirable that the rear side be mirror-finished.

The reflection panels (31), (32), and (33) are made to have different sizes as shown in FIG. 5 in order to increase the lighting efficiency especially at a time when the solar altitude is low. It is also desirable to change the angle. Specifically, the front reflective panel (3
1), as shown in FIGS. 2, 3 and 5, both the height and width are smaller than the other panels, and the central reflective panel (32) is
The height is lower than the rear panel (33), but the width is wider than the rear panel. In addition, reflective panel (31) (3
2) As shown in FIGS. 2 and 5, the lower end of (33) is attached so that the front panel is higher than the rear panel. In the illustrated embodiment, the angle α of an imaginary line connecting the lower ends of the reflection panels (31), (32), (33) is set to 16.7 ° with respect to the horizontal line. Conversely, the upper ends of the reflective panels (31), (32), and (33) should be lower toward the front panel.
Attach it to (34). The angle α of a virtual line connecting the lower ends of the reflection panels (31), (32), (33) is preferably 10 ° ≦ α ≦ 2.
0 °. Since the height of the reflective panels (31), (32), and (33) is changed, when sunlight is received from the front side, the shadow portion of the front reflective panel is reduced, and the reflective panel (31) ( 32)
(33) can be reduced in size and improved in efficiency. Further, the width of the central reflection panel (32) can be made large according to the diameter of the hemispherical dome (20). More reflective panel
(31) Since the heights of the upper and lower ends of (32) and (33) are specified as described above, the portion where the front reflective panel becomes a shadow with respect to the rear reflective panel is reduced and is shown in FIG. Thus, when the solar altitude is low, the sunlight can be directly guided to the lighting hole (90).

The mounting angles θ1, θ2 of the panels (31), (32), (33)
And θ3, the inclination angle becomes smaller toward the front panel,
That is, it is desirable to mount so as to tilt forward (θ1 <θ2 <θ3). In the illustrated embodiment, the mounting angles θ1, θ2,
θ3 is 55 °, 65 °, 70 ° in order from the front panel.
°. Since the mounting angles of the reflective panels (31), (32), and (33) are specified as described above, when the sun altitude before sunrise and sunset is low, the front panel (31) allows more sunlight. The light can be reflected downward to increase the lighting efficiency. In addition, when the solar altitude is high in summer, as shown in FIG. 6, the sunlight L that is shielded by the reflective panels (31), (32), and (33) (indicated by B in the figure) and enters the lighting hole is reduced. Thus, excessive light entering the room is restricted.

As shown in FIGS. 5 and 7, the support frame (34) further includes a power supply means for supplying power to a drive means (60) for rotating the light reflection means (30) and a control means (74). (43)
A solar panel (40) to be charged is provided.
On the hook (35), a solar cell support frame (42) protrudes forward, and a solar cell panel (40) is attached to the tip of the solar cell support frame (42) in an upwardly inclined state. I have. The solar cell support frame (42) may be attached to a rotating shaft (66) described later. Solar Panel (40)
Is mounted so as to be able to rotate integrally with the support frame (34) of the light reflecting means (30), so that it follows the sun integrally with the light reflecting means (30) and performs high-efficiency power generation during sunshine hours Can be.

As shown in FIG. 7, a wiring (46) is connected to the solar cell panel (40), and the wiring (46) is connected to a rotating shaft (66) of the driving means (60) as described later. Through the inside of
It is electrically connected to the power supply means (43).

<Control Box (50)> The control box (50) is, as shown in FIGS.
It is attached to a mounting hole (22) at the top of the dome (20), and as shown in FIG. 5 and FIG.
4) is suspended and supported. The control box (50) is shown in FIG.
And driving means (60), circuit board (70), power supply means shown in FIG.
(43) and the like are housed inside the casing.

As shown in FIG. 9, the casing comprises a bottomed cylindrical casing body (52) and a lid (56). At the upper end of the casing body (52), screw holes (52a) for fixing a circuit board (70) to be described later are formed at equal intervals. Further, a screw is cut on the outer periphery of the upper end of the casing body (52), and a flange (54) projects below the screw. A screw hole (54a) is formed in the flange (54) so as to face a screw hole (22a) formed around the mounting hole (22) of the dome (20). The lid (56) has an inner surface on which the casing body (52) is attached.
The outer edge protrudes so as to cover the flange (54), and closes an upper surface opening of the casing body (52).

A drive means is provided inside the casing body (52).
A gearbox (64) constituting (60) is provided. In the gearbox (64), the motor (62) and the rotating shaft (66)
(Not shown). The rotating shaft (66) is hollow, and includes a power supply means (43) and the aforementioned solar cell panel (4).
0) are passed inside. One end of the wiring (46) protrudes from the side of a joint (80) (described later) provided at the upper end of the rotating shaft (66), and is connected to the power supply means (43). In addition, the other end of the wiring (46) is drawn out to the outside from a wiring extraction hole (66a) opened near the lower end of the rotating shaft (66), and is connected to the solar cell panel (40). Since the wiring (46) passes through the inside of the rotating shaft (66), sunlight is not irradiated on the wiring (46), and the deterioration of the wiring (46) can be prevented.
At the lower end of the rotation shaft (66), a suspension shaft (68) is provided so as to protrude perpendicularly to the axis, and the suspension shaft (68) has a support frame (34) for the light reflecting means (30). A hook (35) projecting from the hook is hung, and the light reflecting means (30) is suspended and supported.

The circuit board (70) is formed in a substantially disk shape, and an angle detecting means (72) is provided at the center of the lower surface, and other control means (74) necessary for controlling the driving means (60) and the like are provided. Will be installed.
The substrate (70) is provided with a chargeable / dischargeable power supply means (43) for supplying electric power to the drive means (60), the control means (74) and the like. In this embodiment, as shown in FIG. 8, a secondary battery (44) and a capacitor (45) are used as the power supply means (43).
(44) the power supply of the control means (74), the capacitor (45) to the motor (6)
2) Power supply. The power supply means (43) is a secondary battery.
(44) or one of the capacitors (45), the rechargeable battery (44) is used as the power source of the motor (62), and the capacitor (45) is controlled by the control means.
The power supply of (74) may be used. As the capacitor (45), a large capacity capacitor (super capacitor) can be exemplified. In the figure, the secondary battery (44) is fitted in a notch (76) formed on the outer periphery of the substrate (70), and the capacitor (45) is attached to the lower surface of the substrate (70). An annular substrate holder (78) for holding the substrate (70) is attached to the substrate (70), and the substrate holder (78) has arc-shaped long holes (78a) penetratingly opened at equal intervals. ing.

As the angle detecting means (72) provided on the substrate (70), a potentiometer whose resistance value changes according to the magnitude of the rotation angle can be exemplified. Angle detection means (72)
Is connected to the rotating shaft (66) via the joint (80) as shown in FIGS. 8 to 10, and the detection result of the angle detecting means (72) is
It is sent to the control means (74). The coupling (80) includes, as shown in FIG. 10, a receiving member (82) fixed to the upper end of the rotating shaft (66),
An engaging member (84) slidable in a direction (arrow direction in the drawing) perpendicular to the rotation shaft (66) with respect to the receiving member (82), and the engaging member (84) is provided with an angle detecting means. (72). The receiving member (82) has a recess (82a) through which the wiring (46) disposed through the rotating shaft (66) is drawn out to the side.

As described above, the secondary battery (44) includes the substrate (70)
And is electrically connected to the control means (74) to supply power to the control means (74),
It is electrically connected to the solar cell panel (40) by the wiring (46) and is charged during the sunshine hours. Also, capacitors (45)
Is electrically connected to the motor (62) to supply power to the motor (62) and to connect the solar cell panel (4
0) and is charged during the sunshine hours.

<Assembly process of sun tracking type daylighting device (10)> The sun tracking type daylighting device (10) having the above-described configuration is composed of the dome (20), light reflecting means (30), and control box (50). Is assembled and transported to the rooftop of the building where it can be assembled. In addition, some or all of the following steps can be performed on the ground.

<Preparation process for mounting sun tracking type daylighting device (10)> The angle detecting means (72) mounted on the substrate (70) of the control box (50) is connected to the rotating shaft (66) by the joint (80). Although it is connected, a slot is provided so that the position of the substrate holding holder (78) can be adjusted in the rotational direction with respect to the casing body (52).
(78a) and the screw hole (52a) are temporarily fixed with screws. The lid (56) is not completely closed or removed. Further, an annular waterproof sealing material (26) is bonded in advance to the mounting hole (22) at the top of the dome (20).
Further, the light reflecting means (30) is assembled on the ground in advance.

<Control Box (5) to Dome (20)
0) Mounting process> First, attach the casing body (52) to the dome (20).
The casing body (52) is rotated and aligned so that the angle detecting means (72) faces a desired direction to a certain extent, and is sealed by the dome (20) and the flange (54). While holding the material (26), the screw holes (22a) (54a) are aligned and screwed. At this time, bonding or the like may be performed as appropriate to enhance the waterproof effect. By the above operation, the control box (50) is mounted on the dome (20).

<Attaching Step of Light Reflecting Means (30)> The hook (35) of the light reflecting means (30) is attached to the suspension shaft (68) of the rotating shaft (66) projecting below the control box (50). Hook. In this state, the wiring (46) is connected to the solar cell panel (40).

<Step of Attaching to Lighting Hole (90)> The dome (20) is attached to the upper end opening of the lighting hole (90). At the connection between the lighting hole (90) and the dome (20), packing rubber or a waterproof seal is appropriately interposed for waterproofing, and the dome (20) is fixed to the lighting hole (90) by bonding or screwing.

<Adjustment of Angle Detecting Means (72)> Since the board (70) is temporarily fixed to the casing body (52), the board (70) is rotated relatively to the casing body (52) in this state. Then, the angle detecting means (72) is directed to a predetermined direction. At this time, the light reflecting means (30) and the rotation axis (66) may be oriented in any direction. Note that the axis of the angle detection means (72) and the rotation axis (6
If the center of 6) does not coincide, it is difficult to rotate the substrate (70), but in the present invention, the angle detecting means (72) and the rotating shaft (66) are connected via the joint (80). Because of the connection, the substrate (70) can be rotated even if there is some misalignment. After adjusting the direction of the angle detecting means (72), the substrate (7
0) to the casing body (52).

<Setting> After fixing the board (70), data such as the latitude, longitude, year, month, day, and time of the installation location are input to the control means (74) using an external input device (not shown). I do.

<Attachment of lid (56)> After data input, the lid (56) is fitted to the casing body (52) and tightened with screws to complete the attachment and assembly of the sun tracking type daylighting device (10). I do.

<Description of Operation> The sun tracking type daylighting device (10)
Based on the input data and the direction of the light reflecting means (30) detected by the angle detecting means (72), the control means (74) drives the driving means (60) according to the installation location. In particular,
During the sunshine period from sunrise to sunset, the light reflecting means (30) is rotated following the sun to guide the sunlight indoors. In addition,
The motor (62) is not driven continuously during the sunshine time, but is driven at predetermined time intervals, for example, every 10 minutes for several seconds to rotate the light reflection means (30) intermittently. Is also good. Further, during the sunshine hours, the solar cell panel (40) receives the sunlight to generate power and charge the power supply means (43). At this time, the wiring (46) connecting the power supply means (43) and the solar cell panel (40) passes through the inside of the rotating shaft (66), and does not hinder the rotation of the light reflecting means (30).

When the sun altitude is low, that is, at the time of winter, sunrise, or sunset, as shown in FIG. 2, sunlight L is irradiated to the sun tracking type daylighting device (10) at a low angle. At this time,
Since the light reflecting means (30) has the lower ends of the reflecting panels (31), (32), and (33) inclined at an angle α toward the sun (front side), a part of the sunlight L is reflected on the reflecting panel. It does not hit and directly enters the lighting hole (90). In addition, the sunlight radiated to the front-side reflection panel (31) is reflected almost immediately below the reflection panel (31) because the reflection panel (31) is inclined at the angle θ1, and is guided to the lighting hole (90). . Accordingly, the lighting efficiency is improved, and sufficient light is provided indoors.

When the solar altitude is high, that is, in the daytime, particularly in the summertime, as shown in FIG. 6, sunlight L is applied to the sun tracking type daylighting device (10) from almost right above. In this case, if the lighting efficiency is high, the amount of light emitted indoors from the lighting hole (90) becomes excessive. However, in the present invention, since the reflection panels (31), (32), and (33) are each provided with the angle θ,
As shown in FIG. 6, the reflection panels (31), (32), and (33) block sunlight L (indicated by B in the figure), and an excessive amount of light does not enter the room.

After sunset, the motor (62) is reversely rotated to rotate the light reflecting means (30) to the sunrise position on the next day.
Similar operations are repeatedly performed. By performing the reversing operation, the wiring (46) is not twisted. The motor
When the capacitor (45) is used as the power supply means (43) of (62), it is desirable to perform the reversing operation immediately after sunset or as soon as possible, in order to suppress a decrease in capacity due to self-discharge. After the reversal operation, even if the capacitor (62) is discharged, the next day, the solar panel (40) is exposed to sunlight and charged by sunrise, and the electric power can be supplied to the motor (62). .

The description of the above embodiments is for the purpose of illustrating the present invention, and should not be construed as limiting the invention described in the claims or reducing the scope thereof. Further, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications can be made within the technical scope described in the claims.

For example, the number, shape, structure,
The mounting angle and the like are not limited to the above embodiment. In the above embodiment, the solar cell panel (4
Although the power supply means (43) charged by (0) is used, a commercial power supply may be used.

[Brief description of the drawings]

FIG. 1 is a perspective view of a sun tracking type daylighting device of the present invention.

FIG. 2 is a cross-sectional view taken along line XX of FIG. 1 and shows a lighting state when the sun altitude is low.

FIG. 3 is a plan view of the sun tracking type daylighting device of the present invention.

FIG. 4 is an assembly diagram of a dome and a control box.

FIG. 5 is a perspective view of a light reflecting means and a control box.

FIG. 6 is a sectional view taken along line XX of FIG. 1 and shows a lighting state when the sun altitude is high.

FIG. 7 is an enlarged perspective view of a portion surrounded by a circle A in FIG. 5;

FIG. 8 is an exploded perspective view of a driving unit, a board, and the like housed in a control box.

FIG. 9 is a cross-sectional view of the control box attached to the dome.

FIG. 10 is a perspective view of a joint.

[Explanation of symbols]

 (10) Sun tracking type daylighting device (20) Dome (30) Light reflection means (31) (32) (33) Reflection panel (40) Solar cell panel (46) Wiring (50) Control box (60) Driving means ( 66) Rotary axis

Claims (4)

[Claims] 1. A dome (20) formed of a translucent material; a light reflecting means (30) disposed in the dome (20) for reflecting sunlight; In a sun tracking type daylighting device including a driving means (60) for rotating the direction according to the direction of the sun, the light reflecting means (30) includes a plurality of reflecting panels (31), (32), (33),
It is arranged with a predetermined interval so that the surfaces of adjacent reflective panels face each other, and the front reflective panel (31) close to the sun is compared with the rear reflective panel (32) (33), A sun tracking type daylighting device, wherein a lower end is higher than a horizontal plane. 2. The sun tracking type daylighting device according to claim 1, wherein an upper end of the front reflective panel (31) is lower than a horizontal plane of the rear reflective panel (32) (33). 3. The reflection panels (31), (32) and (33) are arranged to be inclined with respect to a horizontal plane, and the front reflection panel (31) is higher than the rear reflection panels (32) and (33). The sun tracking type daylighting device according to claim 1, wherein the inclination angle θ is small. 4. The driving means (60) is installed on the top of the dome (20), and the light reflecting means (30) is connected to the rotation axis (66) of the driving means (60).
The sun tracking type daylighting device according to any one of claims 1 to 3, wherein the sun tracking type daylighting device is suspended from the light source.