LIGHTING APPARATUS WITH BRIGHTNESS SELF-ADJUSTMENT AND SELF-ADJUSTING METHOD THEREOF

• US 20150305118A1
• Filed: 10/28/2013
• Published: 10/22/2015
• Est. Priority Date: 11/08/2012
• Status: Active Grant

• Current Assignee: Beghelli S.P.A.
• Original Assignee: Beghelli S.P.A.
• Inventors: BEGHELLI, Gian Pietro
• Granted Patent: US 9,426,867 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H05B 39/042 by measuring the incident light
• CPC Class Codes: H05B 41/3922 and measurement of the incident light
• CPC Class Codes: H05B 45/12 using optical feedback
• CPC Class Codes: H05B 47/11 by determining the brightness or colour temperature of ambient light
• CPC Class Codes: Y02B 20/40 Control techniques providing energy savings, e.g. smart controller or presence detection

Abstract

A lighting apparatus (10) with a brightness control or self-adjustment, comprising an electronic power supply (11) having a brightness self-tuning and a brightness set-point self-calibrator, a sensor (14) for measuring the environment brightness (16) and a control circuit for automatically adjusting the emitted light (18) on the basis of the environment light, so as to keep steady the light in the environment and automatically reduce the emitted light (18) when the environment natural light increases. A method for self-adjusting the environment light sensor (14) allows for obtaining a self-adjusting lighting system on the basis of the natural light in the environment.

Claims

1-4. -4. (canceled)

5. A method for self-adjusting the brightness of a lighting apparatus (10), wherein said lighting apparatus (10) comprises:

a) a regulator (11), which includes a control circuit (13) configured to automatically adjust the brightness (18) emitted from at least one LED or fluorescent light source (17) depending on the environment light, so as to automatically reduce said emitted brightness (18) when the environment light increases, said regulator (11) also including a power supply (12) of said at least one LED or fluorescent light source (17) which is dimmable by means of a dimmer (26) driven by a command signal provided with a PWM technique at the output (25) of a microcontroller (20), and

b) a light sensor (14) configured to measure the environment brightness (16) which is reflected by at least one reference surface, such as the floor, said reflected environment brightness (16) being equal to the sum of said emitted brightness (18) and said environment light, said light sensor (14) being calibrated by means of a brightness self-adjusting algorithm implemented by said microcontroller (20) on the basis of the intensity of said environment light, so as to keep unchanged the amount of said reflected environment brightness (16),

wherein said light sensor (14) is constituted by a phototransistor (21) which incorporates a light correction lens and which measures said reflected environment brightness (16) by providing an electrical current which is proportional to said reflected environment brightness (16) and

wherein said microcontroller (20) is configured to perform a single linear ramp AD conversion of a signal provided at the output of a comparator (24) and said microcontroller (20) also turns on and off, according to a periodic time sequence, a transistor (22) by resetting a capacitor (23), in order to measure a time interval after which said signal at the output of said comparator (24) is equal to zero, said time interval being proportional to said reflected environment brightness (16), wherein said self-adjusting method includes the steps of;

measuring, after a first settled time interval (T₁), said reflected environment brightness (16) by means of said phototransistor (21) either when there is no natural light in the environment or when said at least one LED or fluorescent light source (17) operates at a maximum power,

setting up the value of said reflected environment brightness (16) which is measured by said phototransistor (21) to a first prefixed value of brightness corresponding to an exact value of calibration of said phototransistor (21) when said step of measuring said reflected environment brightness (16) is carried out when there is no natural light in the environment,

adjusting said emitted brightness (18) so as to keep unchanged said reflected environment brightness (16), thus decreasing the power of said at least one LED or fluorescent light source (17) by means of said dimmer (26) when the natural light in the environment increases and vice-versa, up to a minimum value of said emitted brightness (18), wherein said first prefixed value of brightness corresponds to a first and alleged value of calibration when said step of measuring said reflected environment brightness (16) is carried out with natural light in the environment, said at least one LED or fluorescent light source (17) thereby operating at said maximum power for all values of natural light which are less than or equal to the value of natural light detected after said first settled time interval (T₁),

calibrating a set of values of brightness during a second settled time interval (T₂) by setting said maximum power of said at least one LED or fluorescent light source (17) and by measuring said reflected environment brightness (16), and

setting up said calibrated set of values of brightness to a measured value of said reflected environment brightness (16) if said measured value is less than said first and alleged value of calibration and to said first and alleged value of calibration if said measured value is greater than said first and alleged value of calibration,

wherein said lighting apparatus (10) restores said maximum power to said at least one LED or fluorescent light source (17) every time a further calibrating step of said values of brightness is carried out and therefore every time said second settled time interval (T₂) is elapsed, so that, for each calibrating step, said emitted brightness (18) is increased from a current value to a maximum value according to said single linear ramp AD conversion, performed by said microcontroller (20), with a constant slope and for a prefixed time period (T₃), and then is again decreased from said maximum value to said current value according to said single linear ramp AD conversion, performed by said microcontroller (20), with a constant slope and for said prefixed time period (T₃).

6. The method according to claim 5, wherein said lighting apparatus (10) automatically adjusts said value of brightness on the basis of the last value of calibration defined between two subsequent times of further calibration.

7. The method according to claim 5, wherein, after at least five consecutive calibrating step during which said measured value is greater than said first and alleged value of calibration, said exact value of calibration is calculated, for each further calibrating step, by adding to said first and alleged value of calibration one eighth of the difference between said first and alleged value of calibration and a minimum value of calibration logged in at least five previous calibrating steps.

8. The method according to claim 6, wherein, after at least five consecutive calibrating step during which said measured value is greater than said first and alleged value of calibration, said exact value of calibration is calculated, for each further calibrating step, by adding to said first and alleged value of calibration one eighth of the difference between said first and alleged value of calibration and a minimum value of calibration logged in at least five previous calibrating steps.

9. The method according to claim 7, wherein said minimum value of calibration is considered as said exact value of calibration if said at least one LED or fluorescent light source (17) of the lighting apparatus (10) continuously operates for more than 12 hours.

10. The method according to claim 8, wherein said minimum value of calibration is considered as said exact value of calibration if said at least one LED or fluorescent light source (17) of the lighting apparatus (10) continuously operates for more than 12 hours.