Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
  • H05B41/14—Circuit arrangements
  • H05B41/36—Controlling
  • H05B41/38—Controlling the intensity of light
  • H05B41/39—Controlling the intensity of light continuously
  • H05B41/392—Controlling the intensity of light continuously using semiconductor devices, e.g. thyristor
  • H05B41/3921—Controlling the intensity of light continuously using semiconductor devices, e.g. thyristor with possibility of light intensity variations
  • H05B41/3922—Controlling the intensity of light continuously using semiconductor devices, e.g. thyristor with possibility of light intensity variations and measurement of the incident light
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B47/00—Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant
  • H05B47/10—Controlling the light source
  • H05B47/17—Operational modes, e.g. switching from manual to automatic mode or prohibiting specific operations
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B47/00—Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant
  • H05B47/10—Controlling the light source
  • H05B47/175—Controlling the light source by remote control
  • H05B47/19—Controlling the light source by remote control via wireless transmission
  • H05B47/195—Controlling the light source by remote control via wireless transmission the transmission using visible or infrared light
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S315/00—Electric lamp and discharge devices: systems
  • Y10S315/04—Dimming circuit for fluorescent lamps

Definitions

• Lighting control system including a wireless remote sensor
• the present invention pertains generally to the field of lighting control. More particularly, the present invention relates to a lighting control system including a wireless, integrated circuit, sensor for detecting light and/or occupancy in an area.
• fluorescent lamps offer large energy savings as compared to incandescent lamps. Additional energy savings can be obtained through the use of dimmable fluorescent lamp ballasts. These ballasts can be controlled by ballast control circuitry which reduces the level of the light produced by the fluorescent lamp. In this regard, conservation of energy is always an economic and environmental consideration in designing lighting systems.
• the level and type of background illumination has a profound effect on the optimum artificial light needed for a work area.
• the light level in an area also affects the human physiology. It is well accepted that lighting can dramatically affect the circadian rhythm of the human physiological system. Accordingly, it is desirable to control the level of the artificial light to provide an optimum amount of light, see, e.g., U.S. Patents 5,648,656 and 5,459,376, the contents of which are incorporated herein by reference. Lighting systems are known that control, i.e., decrease or increase, the level of artificial light in relation to the level of daylight in an area.
• a light source is turned “on” or “off depending on the presence, or lack thereof, of an occupant in the sensing area.
• determining the state of occupancy within an area can be difficult depending on the positioning of the motion sensor.
• the motion sensor's field of view may be limited or obstructed.
• subsequent rearrangement of an area's contents e.g., furniture
• Some improvement in lighting control technology has been achieved by using multiple light sensors.
• the sensors are tied to a control unit that generates a control signal based on the inputs from the multiple sensors.
• a ballast dimming signal based on some algorithm of multiple sensor inputs to control a light source is known.
• This type of arrangement results in complex installation/setup procedures and expensive equipment requirements.
• this arrangement fails to address the shortcomings of conventional sensor technology discussed above.
• a lighting control system in one aspect of the present invention, includes a light source having a control unit and a wireless receiver.
• the system also includes a sensor having a plurality of pixels and a wireless transmitter, which are formed by a single integrated circuit (IC).
• the sensor transmits data to the light source using the wireless transmitter so that the control unit can control the light source in accordance with the transmitted data.
• One advantageous embodiment of the present invention relates to the use of CMOS imaging technology for the sensor.
• This embodiment enables the integration of multiple functions into one integrated circuit (IC). This results in greatly reduced power requirements as compared to conventional sensors.
• the IC sensor architecture combines a wireless interface, as well as a pixel array for improved daylight harvesting and occupancy detection. The integration of these multiple functions into a single integrated component results in significant cost savings and reduced (installation/equipment) complexity for the lighting control system and sensor.
• Fig. 1 is a diagrammatic view of a room in accordance with one aspect of the present invention.
• Fig. 2 is a schematic diagram showing details of a remote sensor in accordance with a preferred embodiment of the invention.
• Fig. 3 is a block diagram showing a lighting control system in accordance with another aspect of the invention.
• an area such as a room 10 (a portion of which is shown) includes a luminaire, such as a lamp fixture 20, a sensor 30, a work surface 40, an occupant 50, and a remote control unit 60.
• the present invention of course is not limited to the office environment shown in Fig. 1 , but may be used in any domestic environment or surrounding, such as buildings, sporting stadiums, aircraft or ships.
• the lamp fixture 20 may be any controllable light source, such as a dimmable fluorescent lamp.
• the sensor 30 is a standalone device that detects simultaneously illumination from various directions and surfaces in the room 10. This is done to obtain improved control and balance of the light level in the room 10 as compared to conventional lighting control methods that depend on sensing the light level using a single or multiple photodiode sensors.
• the sensor 30 preferably comprises a CMOS pixel (imaging) array 31.
• the present invention is not limited to CMOS technology. Other types of low power dissipating logic technology may be used.
• the sensor 30 also comprises X-decoder 32, Y-decoder 33, A/D converter 34, digital signal processor (DSP) 35, wireless transmitter 36 and a power source 37.
• the pixel array 31 is arranged in rows (x-axis) and columns (y-axis). Of course, other pixel configurations are possible.
• X-decoder 32 and Y-decoder 33 are used to select a respective pixel from the array 31.
• the A/D converter 34 converts the analog data from a respective pixel to digital data in a manner well known in the art.
• the DSP 35 processes the digital data for transmission by the wireless transmitter 36.
• CMOS imaging sensors the reader is referred to U.S. Patent 5,841,126, the contents of which are incorporated herein by reference.
• CCD charged coupled devices
• CMOS image sensors allow for integration of complex signal processing electronics on a single IC. This allow CMOS image sensors to have similar resolution while greatly reducing the power requirements as compared to CCD's.
• CMOS image sensors may have resolutions of tens to hundreds of thousands of pixels (primarily used for video and camera applications). But the preferred resolution results in significant size and cost advantages for the sensor 30. Moreover, as compared to conventional photodiode sensors which offer a resolution of one pixel, the sensor 30's resolution provides considerable improvement in the ability to sense illumination from various directions and surfaces in the room 10.
• This resolution enables the sensor 30 to differentiate simultaneously light from various directions and sources in the room 10. This light may originate from, or be reflected from different sources or surfaces in the area. For example, as shown in Fig. 1, the sensor 30 detects light 11, 12 and 13 from the work surface 40, as well as from windows (i.e., daylight) and wall surfaces around the room 10 (i.e., background or ambient light). This information is collected by the sensor 30 so that an optimum level of artificial lighting for daylight harvesting can be determined as discussed below. Secondly, this resolution also allows the pixel array 31 of the sensor 30 to detect movement of the occupants in the room so that the sensor 30 can also be used as an occupancy detector.
• the senor 30 collects data in each pixel of the pixel array 31. This data is then converted into digital form by the A/D converter 34. The digital data is then processed/analyzed by the DSP 35 to extract key information, such as objects in motion, light levels from various sources and identification of specific features. This information is then formatted by the DSP 35 for transmission by the wireless transmitter 36.
• the sensor 30 can be automatically calibrated through a digital circuit 38, e.g., included in the A/D converter 34, to eliminate analog errors such as drift and offset.
• the digital circuit 38 can also be programmed to adapt the sensor 30 to different environments and lighting conditions, resulting in rapid and trouble-free installation.
• the sensor 30 may have a plurality of predetermined environment settings and operational modes such as:
• Office-window an Office with windows in which the ambient light may fluctuate greatly during the day
• Residential-kitchen a residential kitchen in which bright light is required during the day, but, at night, only directional lighting is needed when an occupant is detected, i.e., providing a pathway to the refrigerator for the late-night snacker
• Freq-Fast (a mode in which updated information is transmitted frequently to control/adjust the artificial light level in a rapidly changing environment); WO 01/11926 ° PCT/EPOO/07301
• Night-On a mode in which the lamp fixture 20 is automatically turn on when no daylight is detected or falls below a predetermined threshold level.
• the lamp fixture 20 includes a wireless interface 21 and a control unit 22.
• the information transmitted by the sensor 30 is received by the wireless interface 21.
• the control unit 22 then processes the information to derive the correct control information (e.g., reduction or augmentation of the light output) based on the room lighting levels and/or the presence of occupants.
• control unit 22 may include ballast control hardware and a microprocessor for executing such algorithms and functions.
• the control unit 22 also processes the information received from the sensor 30 to interpret information transmitted by the sensor 30 in accordance with the various predetermined settings and modes. It is also understood that the environment and mode settings are not necessarily mutually exclusive. Different environment and mode settings may be used together to tailor the lighting control system as needed.
• the information transmitted by the sensor is preferably in a compressed digital format.
• Various compression formats may be used as will be appreciated by one skilled in the art. Compression reduces the transmission power consumption of the sensor 30.
• the information is preferably transmitted at low data rate because such transmission can be performed reliably and using low-power.
• the peak transmission data rate is in the range of lOKbits/second or less.
• the sensor 30 addresses the problem of wiring costs by incorporating the wireless transmitter 36.
• CMOS passive or active RF transmitters are known in the art and have been used for applications such as identification badges.
• the wireless transmitter 36 is a low-power RF transmitter.
• a short range RF transmitter can operate reliably at a power level of one milliwatt or less.
• the low duty cycle can reduce the average RF power level to less than 100 microwatts.
• This type of RF transmitter will provide a short-range link (1-2 meters) between the sensor 30 and the lamp fixture 20.
• other types of wireless interfaces may be used rather than RF, such as IR or ultrasonic interfaces.
• the senor 30 When using a low-power RF transmitter, the sensor 30 is placed in close proximity to the control unit 22. For example, by mounting the sensor 30 to the ceiling near the lamp fixture 20. The wireless communications link is then automatically established. No wiring or drilling holes in the ceiling is required. Moreover, system setup is quick and easy.
• the senor 30 is used to control only its neighbor lamp fixture 20. This allows for easy control of individual lighting in cellular light arrangements. In lighting fixtures in large office rooms, for example, this makes it possible to achieve good daylight harvesting by allowing the fixtures near the windows to respond separately from fixtures that are further removed from the windows. It also permits personalized light setting by the occupant 50, who may wish to control the illumination on the work surface differently when working on the computer or drafting a memorandum.
• the sensor 30 may incorporate identification codes as part of each transmitted information packet. Other control/selection information can also be transmitted in the information packet.
• the control unit 22 of the lamp fixture 20 only accepts information packets with a particular code. This enables the sensor 30 to control multiple lamp fixtures within an area individually. For example, as shown in Fig. 3, a second lamp fixture 20 A also receives and decodes the transmission from the sensor 30.
• the wireless interface to the lamp fixture 20 also results in design improvements and advantages in the control unit 22.
• a CMOS receiver can be easily integrated into a small low-cost IC, perhaps even as part of a main microcontroller IC of the lamp fixture 20 or control unit 22. Only access to a small and inexpensive antenna structure is needed.
• the senor 30 includes circuitry for a wireless receiver 39 (shown in Fig. 2). While a separate circuit block for the wireless receiver 39 may be used, it is preferable that the DSP 35 include this functionality.
• the wireless receiver 39 preferably functions as an infrared (IR) detector so that the lamp fixture 20 can be controlled using the handheld or wall mounted remote control unit 60. The use and popularity of these types of remote control units are increasing.
• the DSP 35 can filter the IR signals from other optical signals detected by the pixel array 31.
• the pixel array 31 can detect both white light and IR signals with efficiency, so that a separate IR photo-detector deceive is not needed.
• IR signals modulate at a high frequency (e.g., 36 kHz from a typical television remote control device) and are digitally encoded.
• the DSP 35 can filter and decode this IR signal from slower varying white light signals.
• Information based on the infrared signals from the remote control unit 60 is combined with other information that is transmitted to the control unit 22 by the sensor 30.
• the wireless interface eliminates the need for wiring and reduces installation costs, particularly for retrofit installations.
• the senor 30 functions as a passive device, or at least operates without a power-source such as batteries or a connection to an external power source.
• a power-source such as batteries or a connection to an external power source.
• This can be achieved through the use of low-power CMOS circuit techniques.
• CMOS circuit techniques By performing the signal processing and data compression (discussed above) on the sensor 30, and using a low-power transmitter only for short periods of time, results in very low IC power requirements, e.g., power levels of less than a 100 microwatts. Since, the power requirements are so low, the sensor 30 can maintain operation via the power source 37 (shown in Fig. 2) using only electromagnetic radiation, i.e., "free" power, which emanates from ambient energy sources. For example, the free power can be obtained from either ambient light, or RF energy from a nearby ballast of the lamp fixture 20.
• the senor 30 may received "free” power from ambient energy sources and also include a battery backup.
• the power source 37 provides power to the sensor 30 to operate using the “free” power and or the battery supplied power. This allows the sensor 30 to conserve the battery energy level by using the "free” power when possible.

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• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Circuit Arrangement For Electric Light Sources In General (AREA)

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Cited By (11)

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• 1999
  • 1999-08-10 US US09/371,374 patent/US6340864B1/en not_active Expired - Lifetime
• 2000
  • 2000-07-28 JP JP2001515660A patent/JP5079196B2/ja not_active Expired - Fee Related
  • 2000-07-28 CN CNB008021791A patent/CN1237850C/zh not_active Expired - Fee Related
  • 2000-07-28 EP EP00948011A patent/EP1118252B1/en not_active Expired - Lifetime
  • 2000-07-28 DE DE60005637T patent/DE60005637T2/de not_active Expired - Lifetime
  • 2000-07-28 WO PCT/EP2000/007301 patent/WO2001011926A1/en not_active Ceased

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