Lighting apparatus with brightness self-adjustment and self-adjusting method thereof

• US 9,426,867 B2
• Filed: 10/28/2013
• Issued: 08/23/2016
• Est. Priority Date: 11/08/2012
• Status: Expired due to Fees

• Current Assignee: Beghelli S.P.A.
• Original Assignee: Beghelli S.P.A.
• Inventors: Beghelli, Gian Pietro
• Primary Examiner(s): Taningco, Alexander H
• Assistant Examiner(s): Luque, Renan
• Application Number:
  US14/441,370
• Publication Number:
  US 20150305118A1
• Time in Patent Office: 1,030 Days
• Field of Search: 315290-295, 315/360, 315/51, 315/384, 315/158, 315/308, 345/82, 345/597, 382/135, 356/243.8, 356/243.1, 702/104
• 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. A method for self-adjusting the brightness of a lighting apparatus, said lighting apparatus including:

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

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

(i) the light sensor including a phototransistor which incorporates a light correction lens and which measures the reflected environment brightness by providing an electrical current which is proportional to the reflected environment brightness and

(ii) the microcontroller being configured to perform a single linear ramp AD conversion of a signal provided at the output of a comparator, the microcontroller turning on and off, according to a periodic time sequence, a transistor by resetting a capacitor in order to measure a time interval after which the signal at the output of the comparator is equal to zero, the time interval being proportional to the reflected environment brightness;

said self-adjusting method comprising;

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

setting the value of the reflected environment brightness as measured by the phototransistor to a first predetermined value of brightness corresponding to an exact value of calibration of the phototransistor when the measuring of the reflected environment brightness is carried out in the absence of natural light in the environment;

adjusting the emitted brightness to a level that keeps unchanged the reflected environment brightness, thus decreasing the power of the at least one LED or fluorescent light source by way of the dimmer when the natural light in the environment increases and vice-versa, up to a minimum value of the emitted brightness, wherein the first predetermined value of brightness corresponds to a first value of calibration when the measuring of the reflected environment brightness is carried out with natural light in the environment, the at least one of the LED or fluorescent light source thereby operating at the maximum power for all values of natural light which are less than or equal to the value of natural light detected after the first settled time interval (T₁);

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

setting up the calibrated set of values of brightness to a measured value of the reflected environment brightness if the measured value is less than the first value of calibration and to the first value of calibration if the measured value is greater than the first value of calibration;

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

the lighting apparatus automatically adjusting the value of brightness on the basis of the last value of calibration defined between two subsequent times of further calibration,

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

wherein the minimum value of calibration is considered as the exact value of calibration if the at least one of said LED or fluorescent light source of the lighting apparatus continuously operates for more than twelve hours.

2. The method according to claim 1, wherein the at least one reference surface comprises a floor.

3. A method for self-adjusting the brightness of a lighting apparatus said lighting apparatus including:

a) a regulator which includes a control circuit configured to automatically adjust the brightness emitted from at least one LED or fluorescent light source depending on the environment light, so as to automatically reduce said emitted brightness when the environment light increases, said regulator also including a power supply of said at least one LED or fluorescent light source which is dimmable by way of a dimmer driven by a command signal provided with a Pulse Width Modulation technique at the output of a microcontroller, and

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

wherein said light sensor comprises a phototransistor which incorporates a light correction lens and which measures said reflected environment brightness by providing an electrical current which is proportional to said reflected environment brightness and

wherein said microcontroller is configured to perform a single linear ramp Analog Digital conversion of a signal provided at the output of a comparator and said microcontroller also turns on and off, according to a periodic time sequence, a transistor by resetting a capacitor, in order to measure a time interval after which said signal at the output of said comparator is equal to zero, said time interval being proportional to said reflected environment brightness,

said self-adjusting method comprising;

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

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

adjusting said emitted brightness so as to keep unchanged said reflected environment brightness, thus decreasing the power of said at least one LED or fluorescent light source by way of said dimmer when the natural light in the environment increases and vice-versa, up to a minimum value of said emitted brightness, wherein said first predetermined value of brightness corresponds to a first value of calibration when said measuring of said reflected environment brightness is carried out with natural light in the environment, said at least one of the LED or fluorescent light source 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 of the LED or fluorescent light source and by measuring said reflected environment brightness, and setting up said calibrated set of values of brightness to a measured value of said reflected environment brightness if said measured value is less than said first value of calibration and to said first value of calibration if said measured value is greater than said first value of calibration,

wherein said lighting apparatus restores said maximum power to said at least one of the LED or fluorescent light source every time a further calibrating 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 is increased from a current value to a maximum value according to said single linear ramp Analog Digital conversion, performed by said microcontroller, with a constant slope and for a predetermined time period (T₃), and then is again decreased from said maximum value to said current value according to said single linear ramp ANALOG DIGITAL conversion, performed by said microcontroller, with a constant slope and for said predetermined time period (T₃), and wherein after at least five consecutive calibrating steps during which said measured value is greater than said first value of calibration, said exact value of calibration is calculated, for each further calibrating step, by adding to said first value of calibration, one eighth of the difference between said first value of calibration and a minimum value of calibration logged in at least five previous calibrating steps.

4. The method according to claim 3, wherein said minimum value of calibration is considered as said exact value of calibration if said at least one of said LED or fluorescent light source of the lighting apparatus continuously operates for more than twelve hours.

5. The method according to claim 3, wherein the at least one reference surface comprises a floor.

6. A method for self-adjusting the brightness of a lighting apparatus, said lighting apparatus including:

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

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

wherein said light sensor comprises a phototransistor which incorporates a light correction lens and which measures said reflected environment brightness by providing an electrical current which is proportional to said reflected environment brightness and

wherein said microcontroller is configured to perform a single linear ramp ANALOG DIGITAL conversion of a signal provided at the output of a comparator and said microcontroller also turns on and off, according to a periodic time sequence, a transistor by resetting a capacitor, in order to measure a time interval after which said signal at the output of said comparator is equal to zero, said time interval being proportional to said reflected environment brightness,

said self-adjusting method comprising;

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

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

adjusting said emitted brightness so as to keep unchanged said reflected environment brightness, thus decreasing the power of said at least one LED or fluorescent light source by way of said dimmer when the natural light in the environment increases and vice-versa, up to a minimum value of said emitted brightness, wherein said first predetermined value of brightness corresponds to a first value of calibration when said measuring of said reflected environment brightness is carried out with natural light in the environment, said at least one of the LED or fluorescent light source 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 of the LED or fluorescent light source and by measuring said reflected environment brightness, and

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

wherein said lighting apparatus restores said maximum power to said at least one of the LED or fluorescent light source every time a further calibrating 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 is increased from a current value to a maximum value according to said single linear ramp Analog Digital conversion, performed by said microcontroller, with a constant slope and for a predetermined time period (T₃), and then is again decreased from said maximum value to said current value according to said single linear ramp Analog Digital conversion, performed by said microcontroller, with a constant slope and for said predetermined time period (T₃), wherein after at least five consecutive calibrating steps during which said measured value is greater than said first value of calibration, said exact value of calibration is calculated, for each further calibrating step, by adding to said first value of calibration one eighth of the difference between said first value of calibration and a minimum value of calibration logged in at least five previous calibrating steps, and further wherein said lighting apparatus automatically adjusts said value of brightness on the basis of the last value of calibration defined between two subsequent times of further calibration.