Solar-powered light assembly with automatic light control

• US 6,573,659 B2
• Filed: 04/02/2001
• Issued: 06/03/2003
• Est. Priority Date: 03/31/2000
• Status: Expired due to Fees

• Current Assignee: Carmanah Technologies Corporation
• Original Assignee: Carmanah Technologies Corporation
• Inventors: Toma, Ion, Siemiatkowski, Zbigniew, Russell, Lysle Brock
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): A, Minh D
• Application Number:
  US09/824,994
• Publication Number:
  US 20020053879A1
• Time in Patent Office: 792 Days
• Field of Search: 315/149, 315/156, 315/157, 315/158, 315/159, 362/183, 362/194, 362/362, 362/372, 362/800
• US Class Current: 315/149
• CPC Class Codes: F21S 9/03 rechargeable by exposure to light
• CPC Class Codes: H05B 47/11 by determining the brightness or colour temperature of ambient light
• CPC Class Codes: H05B 47/16 by timing means
• CPC Class Codes: H05B 47/165 following a pre-assigned programmed sequence; Logic control [LC]
• CPC Class Codes: H05B 47/175 by remote control
• CPC Class Codes: Y02B 20/40 Control techniques providing energy savings, e.g. smart controller or presence detection

Abstract

A solar-powered light assembly comprising at least one light-emitting diode (LED) powered by a rechargeable battery, a solar panel to recharge the battery and to sense light levels, and control circuitry to monitor the rechargeable battery at intervals. At the start of an interval, preferably, the transition from night to day, the control circuitry sets the at least one LED to output light at a pre-determined level based on the battery voltage at the start of the interval. This control scheme is used to adjust the LED output to the available solar illumination recharging the battery to ensure reliable and efficient operation.

Claims

1. A solar-powered light assembly comprising:

at least one light-emitting diode (LED) powered by a rechargeable battery;

a solar panel to recharge the battery and to sense light levels; and

control circuitry to monitor the rechargeable battery at intervals to measure and store the current battery voltage as a stored battery voltage at the start of an interval and to set the at least one LED to output light at a pre-determined level based on a comparison of the current battery voltage with the stored battery voltage from the previous interval.

2. Apparatus as claimed in claim 1 in which the control circuitry monitors the rechargeable battery at intervals corresponding to the transition from night to day.

3. Apparatus as claimed in claim 1 in which the control circuitry activates the at least one LED to output at the pre-determined level only when the ambient light is below a pre-set level.

4. Apparatus as claimed in claim 1 in which:

the control circuitry increases the output level of the at least one LED by a pre-determined amount, unless a maximum output level is already set, if the current battery voltage is greater by a pre-determined amount than the stored battery voltage from the previous interval;

decreases the output level of the at least one LED by a pre-determined amount, unless a minimum output level is already set, if the current battery voltage is less by a pre-determined amount than the stored battery voltage from the previous interval; and

maintains the output level of the at least one LED if the current battery voltage is the same as the stored battery voltage from the previous interval within a pre-determined range.

5. Apparatus as claimed in claim 1 in which the control circuitry provides a constant current from the battery to stabilize the light output of the at least one LED.

6. Apparatus as claimed in claim 1 in which the control circuitry activates the at least one LED to output light in pulses according to one or more flash patterns.

7. Apparatus as claimed in claim 6 in which the control circuitry communicates with a remote control sensor to permit remote changing of the flash pattern of the at least one LED.

8. Apparatus as claimed in claim 1 including a remote control receiver to permit remote control of the light assembly.

9. Apparatus as claimed in claim 8 in which the remote control receiver is an infrared sensor.

10. Apparatus as claimed in claim 8 in which the remote control receiver is a radio frequency sensor.

11. Apparatus as claimed in claim 1 in which the control circuitry activates the at least one LED to output light at a maximum level at the transition from day to night.

12. A method of controlling a solar-powered light assembly having at least one light-emitting diode (LED) powered by a rechargeable battery and a solar panel to recharge the battery and to sense light levels, comprising the steps of:

monitoring the rechargeable battery at intervals by measuring and storing the battery voltage at the start of an interval;

comparing the current battery voltage with the stored battery voltage from the previous interval; and

setting the at least one LED to output light at a pre-determined level at the start of an interval based on results of the comparison step.

13. A method as claimed in claim 12 in which the step of monitoring the rechargeable battery at intervals involves measuring the voltage of the rechargeable battery at the time of the ambient light transition from night to day.

14. A method as claimed in claim 12 in which the at least one LED is set to output light only when the ambient light is below a pre-set level.

15. A method as claimed in claim 12 in which the step of setting the at least one LED to output light at a pre-determined level involves:

increasing the output level of the at least one LED by a pre-determined amount, unless a maximum output level is already set, if the current battery voltage is greater by a pre-determined amount than the stored battery voltage from the previous interval;

decreasing the output level of the at least one LED by a pre-determined amount, unless a minimum output level is already set, if the current battery voltage is less by a pre-determined amount than the stored battery voltage from the previous interval; and

maintaining the output level of the at least one LED if the current battery voltage is the same as the stored battery voltage from the previous interval within a pre-determined range.

16. Apparatus as claimed in claim 12 in which the at least one LED is activated to output light in pulses according to one or more flash patterns.