WO2000066947A1

WO2000066947A1 - Sun reflector system

Info

Publication number: WO2000066947A1
Application number: PCT/GB2000/001606
Authority: WO
Inventors: Richard James Pond
Original assignee: Richard James Pond
Priority date: 1999-04-29
Filing date: 2000-04-25
Publication date: 2000-11-09
Also published as: EP1206665A1

Abstract

A reflective concave mirror (1) mounted on a support strut (2), together with a sensor unit (3) which receives light reflected from the mirror. Light from the sun (5) can be reflected onto the region (6) of a house (4) by the mirror (1), if the mirror is correctly positioned. The mirror is mounted for rotation about the vertical support strut (2) by means of a servo-motor. Another servo-motor (8) enables the mirror (1) to be rotated about a horizontal axis with respect to the post (2). The operation of the motors is controlled by the outputs from an array of light sensors on the unit (3). If the mirror is incorrectly positioned then some of the sensors will be shaded by baffles, thus resulting in the outputs from the sensors differing from one another. An electronic circuit can compare the sensor outputs and send signals to the motors to cause the mirror to be rotated in such a way that the reflected light falls equally on the four sensors.

Description

"Sun Reflector System"

There are many dwellings which either face in a

Northerly direction or are shielded from sunlight by trees or hills. Quite often these dwellings have direct sun on the opposite side of the building or at the lower end of the garden.

The object of this device is to capture sunlight and reflect it back onto the shaded side of the dwelling thus providing sunshine potentially on several sides of the house at the same time, but at least providing natural sunlight which previously was either partially or totally absent.

According to a first aspect of the present invention there is

a sunlight reflecting device comprising a mirror rotatably mounted on a support and having motors to move the mirror rotatably both up and down and from side to side, and a sensor unit mounted in a direction along which the reflected light is required and having an array of sensors facing the mirror and separately responsive to the intensity of light received and connected to control the operation of the motors in such a way as to cause the reflected light or shadow to be received substantially equally on the sensors.

According to a further aspect of the present invention there is provided a solar cell positioning device comprising solar cell panel rotatably mounted on a support and having motors to move the panel rotably both up and down and from side to side, and a sensor unit mounted with the solar panel so as face in the same direction as the solar panel to receive light directly from the sun and having an array of sensors facing in said direction and separately responsive to the intensity of light received and connected to control the operation of the motors in such a way as to cause received light or shadow to be received substantially equally on the sensors.

With these arrangements, as the sun moves on its trajectory, the mirror or the solar panel will be caused to move so that the reflected light is projected along a desired line. Ideally the reflecting mirror will have a convex surface so that the light is spread over a wide area.

The sensors can be provided in pairs respectively in a vertical alignment to control the rotational up and down motion and in a horizontal alignment to control the rotational side to side motion. Another possibility is to provide four sensors in a square array and a comparison device is connected to compare the respective outputs from the two sensors at each side to control the rotational side to side motion and from the upper and lower pairs of sensors to control the rotational up and down motion. Additionally or alternatively to these two proposals the sensors could be splayed out slightly at angles from the axial line of the direction along which the reflected light is required or received.

Furthermore it is possible to provide that the sensors are screened off from one another by baffles aligned with the axial line of the direction along which the reflected light is required or received. The objective of course is to ensure that the sensors are subjected to light of differing intensities if the mirror is not in the required position to project the light from the sun along the desired direction. The device may incorporate a light intensity sensor for switching off the system when the ambient light intensity falls below a predetermined level. This saves power, for example at the end of the day when the sunlight is too weak to be of any real value and can also be used to ensure that the device only switches on when the sun is not heavily obscured by cloud. It may be necessary to provide a manual override to enable the mirror to be adjusted into an approximately correct position when the device is to be put into use (for example when the sun appears from behind thick cloud) . The override could also be used to direct reflected light in a desired alternative direction if it is not wanted on the house, for example.

The invention may be performed in various ways and a preferred embodiment will now be described, by way of example, with reference to the accompanying drawings, in which: -

Figure 1 is a diagrammatic illustration of a sun reflector system of this invention; Figures 2A and 2B are rear perspective and side views respectively of a mirror support unit of the sun reflector system of Figure 1;

Figure 3 is a front perspective view of a sensor unit forming part of the system of Figure 1 ;

Figure 4 is a front view of the sensor unit shown in Figure 3 ;

Figures 5 and 6 are views comparable to those of Figures 3 and 4 for an alternative form of sensor unit;

Figures 7A and 7B are views comparable to those of Figures 2A and 2B for a solar cell positioning system of this invention; and

Figure 8 is a front view of the system shown in Figures 7A and 7B .

The reflector device shown in Figures 1 to 4 comprises a reflective concave mirror 1 mounted on a support strut 2, together with a sensor unit 3 which receives light reflected from the mirror. Figure 1 also illustrates a house 4 which faces generally Northwards and the sun 5 is illustrated in a position during the early part of the morning. Light from the sun can be reflected onto the front of the house 4, in the region 6, by the mirror 1, if the mirror is correctly positioned. As can be seen from Figure 2 the mirror is mounted for rotation about the vertical support strut 2 by means of a servo-motor 7. Another servo-motor 8 enables the mirror 1 to be rotated about a horizontal axis with respect to the post 2. A balancing counterweight 9 is provided.

The operation of the motors 7 and 8 is controlled by the outputs from an array of light sensors 10 on the unit 3

(see Figures 3 and 4) . The sensors are masked from one another by baffles 11. The sensor unit 3 is located directly in line with the desired direction along which the reflected light 12 is required. If the mirror is incorrectly positioned then some of the sensors will be shaded by the baffles 11, thus resulting in the outputs from the sensors differing from one another. An electronic circuit can compare the sensor outputs and send signals to the motors 7 and 8 to cause the mirror to be rotated in such a way that the reflected light falls equally on the four sensors. (Alternatively, as shown in Figures 5 and 6, shadow from a blocking pad 12 can be made to fall equally on the four sensors.) This then ensures that the reflected sunlight is directed along the desired line 12 onto region 6 on the front face of the building 4. As the sun 5 continues on its trajectory round the side and back of the house the mirror 1 will be caused to rotate in a complementary manner so as to ensure that the reflected sunlight continues to extend along the desired line 12. The array of sensors 10 and baffles 11 could be rotated through 45° if desired to provide "upper and lower" and "left and right" sensors.

The reflector should desirably be mounted at some height above the building 4 to reduce potential visual discomfort. This should ideally be at a height to mimic the angle of the sun as if it was shining from that side of the building. The system could also be mounted so that it could be attached to the eaves of a house to shine down the wall. The sunlight reflecting system could be modified to define a solar cell positioning system as illustrated in Figures 7 and 8.

Here a solar panel 12 replaces the reflector mirror and the sensor head 3 is repositioned to the side of the solar panel. For convenience the electronics housing 13 for controlling the motors 9 is repositioned on or near the mounting structure 2. The sensor head remains exactly as shown in Figures 3 and 4 or 5 and 6.

Most static photo voltaic panels are set up to catch optimum sun ray strength around midday by setting the face angle of the panel perpendicular to the sun's rays. Whilst the solar panel works efficiently for a 2 hour period, for the preceding and the subsequent period when the sun is not perpendicular to the panel, efficiency of the system falls off dramatically.

By replacing the reflector mirror of the reflector system with a solar panel and repositioning the sensor head onto the panel instead of on a static bracket, the exact same mechanism control as used for the sun relector system can be used to track the solar panel towards the sun. The sun's rays are then maintained perpendicular to the panel face thus providing highest efficiency at all times of sunlight hours.

In converting sun's rays to electricity, a tapping can be taken to supply the electric circuit to drive the servo motors thus making the entire system totally automonous .

A light intensity sensor could be built into the electronic circuit to ensure that the entire system is switched off if the ambient light intensity falls below a critical level.

It is envisaged that the system will be driven by a low voltage electrical supply which could be supplied from a solar cell.

An automatic adjustment mechanism could be provided to move the mirror to the approximate start position for the morning, after the sun sets in the evening.

Claims

1. A sunlight reflecting device comprising a mirror rotatably mounted on a support and having motors to move the mirror rotatably both up and down and from side to side, and a sensor unit mounted in a direction along which the reflected light is required and having an array of sensors facing the mirror and separately responsive to the intensity of light received and connected to control the operation of the motors in such a way as to cause the reflected light to be received substantially equally on the sensors.

2. A solar cell positioning device comprising a solar cell panel rotatably mounted on a support and having motors to move the panel rotatably both up and down and from side to side, and a sensor unit mounted with the solar panel so as face in the same direction as the solar panel to receive light directly from the sun and having an array of sensors facing in said direction and separately responsive to the intensity of light received and connected to control the operation of the motors in such a way as to cause received light or shadow to be received substantially equally on the sensors .

3. A device according to Claim 1 or Claim 2, wherein the sensors are provided in pairs respectively in a vertical alignment to control the rotational up and down motion and in a horizontal alignment to control the rotational side to side motion.

4. A device according to Claim 1 or Claim 2, wherein four sensors are provided in a square array and a comparison device is connected to compare the respective outputs from the two sensors at each side to control the rotational side to side motion and from the upper and lower pairs of sensors to control the rotational up and down motion.

5. A device according to any one of Claims 1 to 4 , wherein the sensors are splayed out slightly at angles from the axial line of the direction along which the reflected light is required or received.

6. A device according to any one of Claims 1 to 5, wherein the sensors are screened off from one another by baffles aligned with the axial line of the direction along which the reflected light is required or received.

7. A device according to any one of Claims 1 to 6, wherein the reflecting mirror has a convex surface.

8. A device according to any one of Claims 1 to 7, including a light intensity sensor for switching off the system when the ambient light intensity falls below a predetermined level .

9. A device according to any one of Claims 1 to 8 , including a manual override to enable the mirror to be adjusted into an approximately correct position when the device is to be put into use, or to direct reflected light in a desired alternative direction.

10. A sunlight reflecting device or a solar cell positioning device, substantially as herein described, with reference to the accompanying drawings .

11. Any novel combination of features of a sunlight reflecting device or a solar cell positioning device, substantially as herein described and/or as illustrated in the accompanying drawings .