HK1125170B - Low voltage occupancy sensor - Google Patents

Description

Low-voltage occupancy sensor

This application claims priority from provisional application 60/710,062 filed on 22/8/2005.

Technical Field

The disclosure herein relates to occupancy sensors and, more particularly, to low voltage occupancy sensors.

Background

Occupancy sensors are designed to conserve energy by detecting the presence of a moving object within a particular predetermined coverage area and switching the light source on and off in response to the presence of the moving object. Specifically, when a moving object is detected within the coverage area, the light source is turned on. Alternatively, the light source is turned off after a predetermined period of time when no motion is detected, indicating that the coverage area is unoccupied. Thus, by taking over the function of a light switch or an electrical socket, the occupancy sensor can be used to reduce the waste of electrical energy. The purpose of occupancy sensors is to keep the controlled lights on when an area is occupied and turn them off once the area is unoccupied. Occupancy sensors make assumptions about the state of space occupancy from motion detection. Each sensor has a specific field of view (FOV) that enables motion detection. It is important that the FOV of one or more sensors entirely cover the available area of space, and therefore, be able to detect motion from an occupant.

Typical occupancy sensor designs employ ultrasonic and Passive Infrared (PIR) or pyroelectric sensor technologies to sense motion. Some embodiments use only ultrasound, while others use only PIR. Where only one technology is used, such occupancy sensors are referred to as "single" technology type occupancy sensors. Some embodiments use a combination of these two techniques to sense motion. This latter type is called a "dual" or "multi" technology occupancy sensor. The dual technology type sensor turns the light on based on motion detection and keeps the light on based on detection from another technology. This arrangement provides greater security against false opens and false closes.

The occupancy sensor employs an array of fresnel lenses covering an entrance aperture. In operation, thermal infrared light from a moving object of interest strikes the lens array, wherein each lens in the lens array produces a focal spot for any particular angle of incidence. As the object of interest moves through the field of view of the lens array, the focal spot train moves through the sensitive area of the sensor. As a result, the sensor produces a varying electrical output signal that is processed to derive information about the state of motion within the coverage area.

Typically, occupancy sensors detect the presence of a moving object in a particular predetermined area defined by preset coordinates. But sometimes these coordinates need to be adjusted in addition to other variables. Thus, a newly installed sensor may require some adjustment to function optimally at a particular location. However, current occupancy sensor designs do not allow easy, tool-less manual access to adjust the adjustment knobs and switches used to adjust sensor performance. Most occupancy sensors require the cover to be removed using a small screwdriver to make the adjustment. Sometimes, tools are not readily available; even if these tools are readily available, however, the adjustments may require disassembly and reassembly of some parts, including the sensor body. This form of adjustment is not only cumbersome, difficult, but can be damaged during reassembly.

Specifically, installing occupancy sensors requires that proper installation and orientation be previously thought of. The sensor works best when pointed at the occupancy area. However, the coordinates of this footprint are often unknown at the time the sensor is installed. The orientation of occupancy sensors must often change once a room becomes constantly changing, or when changes occur that change the occupancy pattern of the room, such as when furniture arrangements. However, existing occupancy sensors are not very useful in such situations because changing the orientation often requires the sensor to be partially disassembled and reassembled.

There are various means to accommodate the need to change orientation. Some known occupancy sensor designs allow an installer to rotate the entire sensor, including the mounting plate, when the mounting plate is installed with the screw. But the sensor can only be rotated if the screw is not tightly screwed into place. In contrast, the simpler prior occupancy sensors do not allow for rotation if mounted with screws.

Other known occupancy sensor designs allow the sensor to rotate only partially around the mounting plate when the mounting plate is secured with screws. Thus, this design allows only a limited degree of rotation. To achieve certain positioning angles, the installer will need to remove the mounting plate screws and reinstall the mounting plate to the new desired angle. This is time consuming.

In addition to providing directional accessibility, occupancy sensors must allow easy access to the lens, which is a critical component of the occupancy sensor. The lens is made of thin, soft plastic and has a highly sensitive surface. The position of the lens is typically in the center of the sensor to achieve maximum field of view and to cover a large surface area of the sensor. Unfortunately, due to the large exposed surface area of the lens, the lens may be scratched or damaged by accident during transport and handling or during installation. Accordingly, if the lens is damaged, the sensor will not perform optimally. In most known occupancy sensor designs, when the lens is damaged, the entire sensor must be replaced. Removing and reinstalling the sensor can be a time consuming task.

Alternatively, in some known occupancy sensor designs, the lens is held in place with a small plastic ring. To remove the lens, this ring must be snapped off the housing. Unfortunately, when picking off the loop, it is inevitable that the lens surface will be touched by the person removing the lens, because the loop is of small size. Thus, removing the lens may degrade lens performance due to oil and dirt carried by the person removing the lens' hands.

Thus, there is a need for an occupancy sensor that: it can be accessed manually without the use of tools to allow the installer to adjust various features of the sensor. Further, there is a need for an occupancy sensor that incorporates a simple installation and reorientation scheme. Furthermore, the sensor must be able to easily access the lens to replace a defective lens without damaging or improperly disposing of the new lens.

The present invention is directed to overcoming, or at least reducing, the effects of, one or more of the problems set forth above.

Disclosure of Invention

To address the shortcomings of occupancy sensors discussed above, the present invention teaches an occupancy sensor that enables tool-less manual access to adjust several features of the sensor. More specifically, this invention allows for tool-less manual adjustment of various switches and knobs to change sensor settings. Moreover, such occupancy sensors have a simple installation scheme. In addition, the lens of the sensor is replaceable without changing the entire unit. Moreover, to provide additional protection to the lens, the snap-on cover is significantly larger in size than the lens. Thus, when the cover is removed, the user's fingers are moved away from the lens itself, which minimizes the possibility of the lens becoming dirty while the unit is being serviced. Such a removable cover also gives the user the opportunity to change the color of the device to match the upholstery.

Other portions of this invention allow for easy rotation of the unit depending on the desired orientation of the occupancy sensor by allowing the sensor base to rotate approximately 360 degrees relative to the back cover using a circular track having a harmonic gear-type profile resembling a sine wave. The occupancy sensor according to the present invention may be rotated to accommodate the desired coverage pattern. This profile allows for appropriate tactile and audible feedback to the user. An additional feature of this sensor is that the rear cover has four elongated slots that allow the device to be mounted to a variety of electrical boxes or directly to building components that do not require electrical boxes.

Specifically, a housing for an occupancy sensor according to the present invention includes a cover assembly having an aperture in which a lens assembly is seated. The housing includes a base assembly having a base, a harmonic wheel, and a back cover, wherein the harmonic wheel is sandwiched between the base and the back cover. A harmonic wheel within the base assembly enables the base to rotate about the base cover. The cover assembly is coupled to the base assembly such that the cover assembly can be manually removed to allow an installer to adjust the occupancy sensor.

The lens of the lens assembly may be a fresnel lens, a non-fresnel lens, or a cap that does not require a lens. In one possible application, a mask associated with the lens may be used to selectively block the detection field of the sensor. The lens holder of such a device is designed to contain any lens option.

In general, such single or multi-technology occupancy ceiling sensors may be assembled within a hemispherical enclosure, wherein the cover assembly has a replaceable cover with convenient adjustment and installation solutions. This design provides two main features to the ceiling sensor: easy installation and adjustment without tools. In the event that the lens is scratched or damaged, the replaceable cover design allows for the installation of a new lens without the expense and need to replace the entire sensor.

The foregoing has outlined, rather broadly, the preferred feature of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features of the invention will be described hereinafter which form the subject of the claims of the invention. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for designing or modifying other structures for carrying out the same purposes of the present invention. Although the invention is implemented in hardware, other equivalent implementations of hardware, firmware and software may be used, in whole or in part. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention in its broadest form.

Drawings

Other aspects, features and advantages of the invention will become more fully apparent from the following detailed description, the claims and the accompanying drawings. In the drawings:

FIG. 1 illustrates a ceiling occupancy sensor;

FIG. 2 is an exploded view of the occupancy sensor;

FIG. 3 is an exploded view of the base assembly of the occupancy sensor;

FIG. 4 shows a harmonic wheel;

FIG. 5 shows a rear cover;

FIG. 6 shows an exploded view of the lens assembly;

FIG. 7 shows an exploded view of a second embodiment of a lens assembly;

FIG. 8 shows a base assembly;

FIG. 9 is a view showing a function adjustment icon;

FIG. 10 illustrates a one-way ceiling occupancy sensor;

FIG. 11 shows an ultrasonic two-way ceiling occupancy sensor;

FIG. 12 shows an ultrasonic one-way ceiling occupancy sensor;

FIG. 13 shows a PIR-only ceiling occupancy sensor;

fig. 14 shows the back cover of the ceiling occupancy sensor.

Detailed Description

The present invention will now be described with reference to the accompanying drawings. Various embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

The occupancy sensor according to the present invention enables tool-less manual access to the control switches and lens located on the sensor base assembly. The occupancy sensor includes a cover assembly connected to a base assembly. Removing the cover assembly enables the user to adjust several components of the sensor. Specifically, the user can remove the front cover and then manually adjust the various switches and knobs to change the settings of the sensors at any point in time. Furthermore, occupancy sensors involve a simple installation solution, which further enables easy adjustment of the sensor. The harmonic wheel contained in the base assembly effects rotational movement of the sensor such that the sensor can be rotated from substantially 0 degrees to substantially 359 degrees about its initial set position. Thus, the occupancy sensor according to the present invention is able to rotate to accommodate various desired coverage patterns. There are several new improved features in the design of occupancy sensor 100 that are intended to be improvements over prior art devices and allow for a universal mounting. These include, but are not limited to, a front cover, a harmonic wheel, a rear cover, and a lens holder.

Referring to fig. 1, occupancy sensor 100 includes a housing made up of two pieces, a front cover 10 and a base assembly 40. Lens assembly 20 is seated in front cover 10. The circular vents or grills 80, 82, 84, 86 provide access to transducers below the grills to sense or transmit ultrasonic energy. The projections 88, 90, when pushed in, enable the cover 10 to be removed or snapped into place atop the base assembly 40. Although a hemispherical shell is shown, those skilled in the art will appreciate that the physical differences in the shape of the shell can be varied while maintaining the functionality described above. For example, the sensor may be square, box-shaped or oval.

In operation, the multi-technology two-way occupancy sensor 100 utilizes both Passive Infrared (PIR) detectors (or pyroelectric sensors) and ultrasonic sensors to sense motion. PIR detectors are sensitive to temperature generated by heat sources such as infrared energy from the human body. A human has a skin temperature of about 98F and radiates infrared energy at a wavelength between 9 and 10 microns. Thus, PIR sensors are typically sensitive in the 8-12 micron wavelength range. More specifically, PIR detectors comprise simple electronic components like photosensors in which infrared light strikes electrons off a substrate, which electrons can then be detected and amplified into an electrical signal.

On the other hand, the ultrasonic probe emits ultrasonic waves, which bounce back from the object. Reflected waves after hitting an object such as a person will produce doppler shifts in both phase and frequency. An electronic circuit within the ultrasound probe filters the reflected waves and amplifies the doppler shift to determine if the object is moving. The signal is then sent to a power pack which may include a relay switch. These relay switches are wired to control one or more lights.

Referring to fig. 2, this exploded view of the occupancy sensor 100 shows the cover 10 removed from the base assembly 40. As shown, circular vents 84, 86 are openings for the transducers 92, 94, respectively, and circular vents 80, 82 (see fig. 1) are openings for the transducers 95, 93, respectively. When the cover is removed, the knob and switch 96 is accessible for the user to adjust the various controls of the sensor 100. The illustrated construction utilizes a replaceable snap-on front cover 10. The snap-on bezel 10 is designed to be removed without the use of any tools and, when removed, exposes a dual in-line package (DIP) switch and adjustment knob 96. More disclosure regarding these user controls is provided below.

Referring to fig. 2, the lens 20 is held in place in the front cover 10 which can be easily removed without the use of tools. When the lens 20 needs to be replaced, only the snap-in bezel 10 needs to be replaced. The entire sensor does not have to be removed. Thus, the design of this occupancy sensor 100 allows the front cover 10 to be quickly and easily replaced when the lens 20 is damaged, becomes useless due to vandalism or any other reason, and must be replaced. The front cover 10 has a snap-on design and can be easily attached to and removed from the housing without the use of any tools. The nature of this "tool-less" replacement design reduces the risk of injury to the installer.

Another feature of this sensor is that the front cover 10 is larger than the lens. The larger surface area of the cover 10 reduces the likelihood of hitting the lens 20 when adjusting and/or replacing the sensor. This feature helps to keep the lens 20 free of dirt and oil from the user or installer's hands. The removable front cover 10 can be quickly and easily replaced with a cover of a different color to provide a device that is compatible with different upholstery.

Fig. 3 shows an exploded view of the base assembly 40 including the base 42, the harmonic wheel 44, and the rear cover 46. The harmonic wheel 44 is positioned between the base 42 and the rear cover 46 to provide a tool-less adjustment design. The base 42 of the sensor can be rotated between 0 and 359 degrees relative to the stationary back cover to allow the sensor to be rotated to a desired angle after the back cover is permanently attached to the ceiling. Thus, the sensor can be rotated substantially 360 degrees regardless of its initial orientation when installed or secured to a building element. Such sensors are designed to be mounted only to the ceiling and the cover is rotated about its base to "aim" transducers 92, 93, 94, 95 (see both figures 2 and 3) located within the base assembly at the area that would normally be occupied. The sensor 100 (see fig. 10) has a set of transducers on only one side and is therefore considered to be of the unidirectional type. The sensor 200 (see fig. 11) has two sets of transducers on opposite sides and is therefore considered to be of the bi-directional type. The different versions can provide a variety of different detection patterns to help provide optimal performance, such as is often useful for open spaces, hallways, and warehouse aisles.

Fig. 4 shows a cross-sectional view of the harmonic wheel 44. As shown, the protrusion or gear 48 has a sine wave-like shape that helps provide a proper balance between maintaining the sensor in its desired orientation and allowing it to rotate in 3 degree increments. This design provides both a large and a small adjustment to the sensor orientation, and the sine wave-like design of the gear 48 provides both a tactile and an audible feedback to the installer.

The harmonic wheel 44 is designed to fit into the base 42 in only one position, which simplifies the assembly and installation process of the sensor. Referring to fig. 4 and 5, the projections 50 slide into the mounting holes 56 of the rear cover 46. Specifically, the rear cover 46 includes a large central opening to accommodate a threaded rod (not shown). The screws may be attached to rails for mounting the back cover to the ceiling. Four elongated mounting slots 52 separated by 90 degrees and oriented along a radius of the back cover are provided for installation using mounting screws (not shown).

Mounting holes 56 on the rear cover 46 allow the rear cover to be mounted directly to Standard 1 described below¹/₂"deep electric box: 3¹/₂"disc, 4" disc, 3¹/₂An "octagonal shape, a 4" round protrusion cap with open ears, a4 "square to round protrusion cap with open ears, and 4¹¹/₁₆"Square protruding cap with open ears (neither shown).

Electrical specifications vary based on region. Certain areas require low voltage sensors to be housed within an enclosure such as an electrical box. An occupancy sensor according to this invention can be adapted for direct mounting into a variety of different electrical boxes. Additionally, such sensors may be mounted to other electrical boxes with commercially available adapters. Some areas allow the ceiling-mounted occupancy sensor to be mounted directly to a building component without the need for any enclosures. Occupancy sensors according to the present invention are also adaptable to these types of installations. Thus, the back plate of the occupancy sensor can accommodate a variety of different installation scenarios. An additional mounting solution may include the use of a4 inch square box with a raised cover. Another application may include the use of occupancy sensors for trunking applications that are mounted to wall panels. Direct mounting with screws to a standard wireway electrical box (i.e., wiring template) is a viable option. The rear cover 46 can be mounted to a standard crossbar using mounting screws. With a deeper size octagonal or square box with protruding covers with open ears, the applied screws can be mounted onto standard crossbars, which eliminates the need for screws.

Fig. 6 illustrates an exploded bottom view of the front cover and lens assembly. The cover 12 has a substantially central aperture for receiving the lens 20. The lens holder 14 fits over the lens 20 and holds the lens 20 in place on the cover 12. A mask 24 mounted to the lens holder 14 is used to block a portion of the coverage pattern.

The holder 14 is designed to hold more than one part, since several parts must be held in place on the front cover. With the many variations available in occupancy sensors, some require the use of a Fresnel lens, while others do not. To avoid the need for different covers for different versions, the lens holder 14 is designed to hold both the Fresnel lens 20 and the mask (if desired) and alternatively only the cap 16. See fig. 7 without the use of a fresnel lens. Referring to FIG. 6, where a Fresnel lens is used, Fresnel lens 20 is held firmly in place by lens holder 14, which lens holder 14 is non-removably secured to front cover 12 by heat staking bosses on the inside surface of front cover 12. The heat staking involves the process of heating the metal bosses (b1, b2, b3, b4) of the inner surface of the front cover and then inserting the metal bosses into the plastic lens holder. Hot staking of threaded metal inserts into plastic is often necessary because most thermoplastic materials are too soft to adequately retain the threads. A brass or steel threaded insert may be added. The mask 24 used with some sensors may be mounted on the bottom side of the lens holder 14.

Referring to fig. 7, an exploded view of the lens holder 14, front cover and cap 16 is shown. Initially, the annular lens holder is securely attached to the inner surface of the front cover. The cap 16 is inserted and pressed into the opening in the front cover until the catches x, y on the cap lock into place in the slots in the front cover 12 and lens holder 14. Returning to fig. 6, the mask 24 may be installed by the user to obtain a more specific coverage pattern. The cap 24 is mounted to the top side of the annular lens holder 14.

The lens holder disclosed herein is a common part, having the function of several parts, thus reducing cost and assembly time. As shown in fig. 6 and 7, the annular lens holder 14 may engage at least three separate distinct pieces: fresnel lens 20 and mask 24, or just cap 16.

Fig. 8 and 9 illustrate details of one embodiment of a base assembly 40 of an occupancy sensor. The slots 58, 62, 64, 68 are positioned to enable the front cover 10 (figures 6 and 7) to be fastened to securely attach to the base assembly 40. In addition to these slots, a number of user controls are provided, such as 4 adjustment knobs (potentiometers) 63, 65, 66, 67 and 2 4-position dip switches A [ SW-A1, SW-A2, SW-A3, SW-A4], B [ SW-B1, SW-B2, SW-B3, SW-B4 ]. The adjustment knobs may be provided with an ultrasonic sensitivity knob 63, an infrared sensitivity knob 65, an ambient light adjustment knob 66, and a time delay knob 67. Fig. 9 shows icons representing related function adjustments. The time delay knob 67 provides a selection of a selected base time delayed for a specific period of time that the sensor waits before switching the lamp on and off. These options may include 30 seconds, 5 minutes, 10 minutes, 20 minutes, and 30 minutes. The ambient light knob 66 sets the light level for which the lights will remain off when natural light is available. The infrared sensitivity knob 65 adjusts the sensitivity of the PIR circuit, which changes the gain. The ultrasonic sensitivity knob 63 changes the gain and threshold of the ultrasonic circuit/signal analysis.

Further, there may be 8 dip switches (not shown) that provide enhanced functionality. The first switch SW-a1 switches the sensor from "single" technology mode to "multiple" technology mode. When switch SW-A1 is OFF, sensor 100 is in a "multiple" technology (multiple technology) mode. When switch SW-A1 is ON, sensor 100 is in the single technology mode. The switch SW-a1 is only useful in the multi-technology embodiment 100, 200 (see fig. 10). The switch SW-a1 may be used in situations where a technique does not work well and for diagnostics. Switch SW-a2 switches the sensor from the FIR probe to the ultrasound probe. When switch SW-A2 is OFF, sensor 100 uses a PIR detector. When switch SW-A2 is "ON," sensor 100 uses an ultrasonic probe. Accordingly, the switch SW-A2 is only useful in the multi-technology embodiments 100, 200. In addition, for switch SW-A2 to be operable, switch SW-A1 must be "ON". Specifically, the switch SW-A2 selects which technology to use during the single technology mode. This selected technology is only the technology used to turn on and maintain the lamp. The switch SW-A3 specifies a manual mode in which adaptation is enabled when the switch SW-A3 is "off" and disabled when the switch SW-A3 is "on". This feature includes delayed off-time (delayed off-time) and daytime adaptation time. The switch SW-A4 provides walk-through disable, wherein when the switch SW-A4 is OFF, the disable is OFF, meaning the walk-through feature is ON. The walk-through feature makes the occupancy sensor less sensitive than the usual mode of operation. The walk-through feature is used to place occupancy sensors in highly open traffic areas such as hallways. This feature is necessary when the sensor is placed in an office. In the office, people seek to limit the sensitivity of the sensor when a supervisor is in the lobby after work hours. Conversely, when switch SW-A4 is "ON", the disable is "ON", which means that the walk-through feature is "OFF". The switch SW-B1 provides an override for the on feature, and the lamp is forced on when the switch SW-B1 is on. When SW-B1 is OFF, sensor 100 is in automatic mode. Conversely, switch SW-B2 provides an override for the "off" feature, wherein sensor 100 is in the automatic mode when switch SW-B2 is "off". When switch SW-B2 is ON, the lamp is forced OFF. Switch SW-B3 provides a walk test that enables the test mode. When the switch SW-B3 is switched in the following order: "off", "on", "off", sensor 100 enters a test mode. The same sequence must be used to exit this test mode. The adaptive settings are reset when the test mode is entered. Switch SW-B4 provides LED disable. When switch SW-B4 is OFF, the LED is disabled, meaning that the LED will remain ON. When switch SW-B4 is "ON", the LED is disabled to "ON", which means that the LED will remain "OFF".

As discussed previously, the sensors produce varying electrical output signals that are processed to derive information about the state of motion within the coverage area. This electrical output signal is fed to a microcontroller which samples the signal at a sampling rate of 1 KHz. A digital bandpass filter with an 80KHz center frequency filters this sampled signal. This filtered signal is then passed through a peak detector. The output of the peak detector is applied to both a low pass filter and a narrow bandpass filter. The dc value of the signal is extracted to produce a threshold. The output of the peak detector is fed to a low pass filter to obtain this dc value. In addition, the output of the peak detector is fed to a second low pass filter to smooth the signal. The threshold is established based on this dc value. The ac component of the signal is extracted with a narrow band-pass filter centered around 20 Hz. Correction of the threshold value is based on a number of factors, including adjustment of the potentiometer, occupancy status, and history collected per monitoring cycle. This threshold is compared with the ac component of the signal after taking into account all corrections. An occupancy event occurs when the AC component is greater than a threshold.

There are three basic types of 8 ceiling sensor embodiments: PIR only, ultrasonic only, and multi-technology. The multi-technology embodiment includes the various features previously described in connection with each associated switch SW-A, SW-B. Other models are based on having single technology type elements and associated specific technologies, with some features removed. There are two only FIR-type models: extended range models and high density models. Each sensor has a different lens providing a different FOV.

Fig. 10, 11, 12, 13 show four different embodiments. Three of these embodiments are multi-technology type sensors, including unidirectional with a 500 square foot range, bidirectional with a 1000 square foot range, and bidirectional with a 2000 square foot range. These embodiments have a FOV that is a composite of the extended modality of the PIR embodiment and the extended modality of the three different ultrasound embodiments. In particular, the first embodiment of the occupancy sensor 100 according to the invention as shown in fig. 1 is a multi-technology, two-way occupancy sensor. The FOV of this sensor covers a 360 degree range around both sides of the sensor, whereas the one-way occupancy sensor 200 of FIG. 10 covers only the FOV located 180 degrees to one side of the sensor. The bi-directional embodiment 100 has two pairs of transducers, one on each side, covering 360 degrees. Fig. 10 shows a multi-technology one-way occupancy sensor 200 in which cover 210 has a lens assembly 220 connected to a base assembly 230. The cover 210 includes grills 240, 242. As shown, this unidirectional embodiment 200 has a cover 210 with only one set of louvers 240, 242.

There are three merely ultrasonic embodiments, including: unidirectional (with a range of 500 square feet), bidirectional (with a range of 1000 square feet), and bidirectional (with a range of 2000 square feet). The unidirectional embodiment has only one pair of ultrasonic transducers. The FOV of this ultrasonic-only embodiment covers only 180 degrees on one side of the sensor. This one-way embodiment has a cover with only one set of grates. The bi-directional embodiment has two pairs of transducers, one on each side, covering 360 degrees. The sensor embodiment covering the 2000 square foot range is the same as the other ultrasonic-only embodiments, except that a 32KHz transducer is used to obtain the additional range. Others are just ultrasonic sensors operating at 40 KHz. Several features are not present in the ultrasonic-only embodiment, including the use of switches A1 and A2 to provide multiple techniques to enable the PIR circuit. Specifically, FIG. 11 illustrates an ultrasonic two-way occupancy sensor 300 that includes a cover 310 having grills 330-336 and attached to a base assembly 320. Fig. 12 shows an ultrasonic one-way occupancy sensor 400 that includes a cover 410 having grills 430, 432 and attached to a base assembly 420.

In operation, the ultrasonic sensors 300, 400 detect the doppler shift of the reflected signal. When the sound wave hits a moving object, a reflected sound is generated. This reflected wave has a small shift in frequency from the incident wave. This displacement is detected by passing the received signal through a demodulator to produce a signal having a voltage proportional to the frequency displacement. In particular, the ultrasonic sensor may have one or two sets of transmitters and receivers. Sensor 400 has one set (one transmitter and one receiver) and sensor 300 has two sets. The transmitters are connected in parallel and the outputs of the receivers are summed. Thus, it is sufficient to analyze one group. The ultrasonic transmitter generates ultrasonic waves of a specific frequency. These waves are reflected from various objects in the space (walls, furniture, people, etc.), and the reflected waves are then detected by an ultrasonic receiver. The reflection from an inactive object has the same frequency as the transmitted wave. Reflections from moving objects are detected with different frequencies. The frequency difference is in the range of 1% or less in consideration of the speed of sound, the operating frequency, and the speed of human motion. The received signal is a sine wave that is modulated in frequency and amplitude. This signal must be demodulated to remove the carrier, leaving amplitude and frequency detection. Since all reflections come from stationary and moving objects, the received signal will always have some amplitude modulation. In a room with no airflow or moving objects, the amplitude modulation will remain fairly constant and will produce zero output when averaged over time. When motion occurs, there will be a greater amplitude modulation, but this is not sufficient to reliably detect motion over a distance. Frequency modulation will provide small variations that can be more reliably amplified.

Fig. 13 shows an occupancy sensor 500 that is only a Passive Infrared (PIR) type that includes a cover 510 having a lens 520 and a base member 530, the lens 520 extending outwardly from an upper surface. As shown, this PIR-only embodiment has a cover without a grill. Several features are not present in PIR only embodiments, such as those associated with multi-technology, ambient adaptive and ultrasonic circuits.

In operation, PIR technology uses a pyroelectric sensor in conjunction with a Fresnel lens array to detect heat from a moving person. The output of the pyroelectric sensor is amplified and filtered to provide a signal at a dc reference voltage. When the pyroelectric sensor generates an output, the signal has an alternating current characteristic. The signal is processed via a microcontroller built into the a/D converter. If the signal voltage is outside the predetermined window, then motion is interpreted as present. The actual value of the window (or threshold) depends on the state of the sensor. When the light is off, the window will become larger; when the light is turned on, the window will become smaller. The minimum window size is determined empirically by measurement.

Fig. 14 illustrates the back cover of various embodiments of occupancy sensors 100, 200, 300, 400, 500.

In general, advantages of the disclosed sensor design include, but are not limited to, occupancy sensors such as: by enabling a tool-less, manually removable cover assembly to adjust the settings of the sensor and/or remove the lens assembly, time and expense during installation and adjustment is saved. When the lens is scratched or damaged, the replaceable bezel design allows for the installation of a new lens without the expense and need to replace the entire sensor. During installation, the sensor can be manually rotated to any position, which further amounts to savings in time and expense.

All the features disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The terms and expressions which have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.

Claims (17)

1. An occupancy sensor comprising:

a front cover with an opening;

a lens assembly coupled and positioned in the opening of the front cover, wherein the lens assembly comprises:

an annular member;

a Fresnel lens coupled to one side of the annular member,

wherein the annular member and the Fresnel lens are non-removably coupled to the front cover;

a rear cover; and

a base assembly having a radiation detector, the base assembly coupled to the front cover and rotatably coupled to the back cover to provide angular orientation of the lens assembly by manually rotating the front cover.

2. The occupancy sensor of claim 1 wherein the back cover is adapted to be coupled to a ceiling.

3. The occupancy sensor of claim 2 wherein the back cover comprises: a central opening adapted to receive the screw.

4. The occupancy sensor of claim 2 wherein the back cover comprises: at least two elongated mounting slots, each of the mounting slots positioned along a radius of the rear cover for receiving a screw for directly coupling the rear cover to an electrical outlet box.

5. The occupancy sensor of claim 4 wherein the rear cover has four elongated mounting slots evenly spaced around the rear cover, each mounting slot being located along a radius of the rear cover.

6. The occupancy sensor of claim 1 wherein the annular member is heat staked to an inner surface of the front cover.

7. The occupancy sensor of claim 1 further comprising: a mask coupled to a second side of the annular member.

8. The occupancy sensor of claim 1 wherein the fresnel lens extends through the opening and beyond an outer surface of the front cover.

9. The occupancy sensor of claim 1 wherein the lens assembly comprises:

an opaque cap; and is

Wherein the annular member is bonded to an inner surface of the front cover adjacent the opening for frictionally receiving the opaque cap.

10. The occupancy sensor of claim 9 wherein the opaque cap includes a flange that abuts an outer surface of the front cover when the cap is inserted into the annular member from the outer surface of the front cover.

11. The occupancy sensor of claim 1 further comprising: a harmonic wheel positioned between the back cover and the base assembly for allowing the base assembly and the front cover to rotate relative to the back cover.

12. The occupancy sensor of claim 11 wherein the rotation of the base assembly and the front cover relative to the back cover is between 359 degrees and 0 degrees.

13. The occupancy sensor of claim 11 wherein the harmonic wheel has shaped protrusions to allow the base assembly and the front cover to be manually rotated in discrete increments relative to the back cover.

14. The occupancy sensor of claim 13 wherein the discrete increments are 3 degrees.

15. The occupancy sensor of claim 13 wherein the shaped protrusions are sine wave-like structures.

16. The occupancy sensor of claim 13 wherein the harmonic wheel is non-rotatably coupled to the rear cover.

17. The occupancy sensor of claim 16 wherein the harmonic wheel includes a protrusion that engages in a receiving opening in the rear cover to lock the harmonic wheel in a non-rotatable relationship with respect to the rear cover.