Patent Application
20080074652
The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
Embodiments of the present invention provide a system and method for electronic access control. In one embodiment of the invention, the direction of travel of a person or object through a corridor can be determined. In another embodiment of the invention, if an object or person enters into a restricted area, an alarm signal is generated. Therefore, if a guard in an airport for example is distracted, embodiments of the present invention can sound an alarm to enforce security.
Embodiments of the present invention generate a sheet (e.g., a two dimensional plane) or box (e.g., a three dimensional volume) of light that protects a point of entry or a corridor form unauthorized entry. In one embodiment of the invention, a light plane is used to monitor entry of objects through a doorway or window. In another embodiment of the invention, a box of light is generated to monitor travel of objects in a corridor or hallway, for example, monitoring the direction of travel and only allowing objects to travel in one direction through the corridor. In one embodiment of the invention, an alarm is activated in response to detecting travel in the incorrect direction.
In the case of a window to a house, for example, embodiments of the present invention generate a signal to sound an alarm when an intruder breaks a plane or sheet of light monitoring a point of entry (e.g., a door, window, ventilation duct, etc.). In another embodiment of the invention, objects are allowed to pass through a point of entry in a particular direction without triggering the alarm.
In the case of an elevator or garage door, embodiments of the present invention can be coupled to the opening-closing mechanism such that when a person or object breaks a light array monitoring the opening, the closing-opening mechanism is disabled, thus rendering the mechanism useless to the intruder or from harming someone in the way of a moving object. While many elevators and garage door opening systems use some sort of optical technology, they typically only check clearance at one height. The systems are easily overcome by stepping over the single beam, for example.
In one embodiment of the invention, comparing the time of light interruption for photodetectors arranged in an array along the direction of restricted movement can allow the direction of travel (e.g., right direction vs. wrong direction) to be determined electronically. If a person is detected traveling in the wrong direction, an alarm can be sounded.
In another embodiment of the invention, a linear array of sensors can be arranged along a hallway. The sensors should be arranged such that they are close enough to the ground to prevent someone crawling underneath and close enough together to prevent someone from stepping in between them, such an array can be used to detect travel in the wrong direction.
Some benefits of embodiments of the present invention include reduced numbers of security guards at entry points or travel corridors and guarding points of entry that were considered unarmable with conventional entry detection systems which provides added safety to occupants of buildings and homes. In addition, embodiments of the present invention provide security to windows and doors even in their open state allowing one to keep windows open for ventilation while maintaining a level of protection. Furthermore, safety can be greatly improved by incorporating embodiments of the present invention into opening and closing mechanisms such as automatic doors to prevent unintentional closing or opening of a door on a person or object.
Other benefits of the present invention include simplicity in electrical requirements since embodiments of the present invention only require electricity on one side of an area being protected. In one embodiment of the invention, a retroreflector is used to reflect light back to a sensor which does not require electricity to operate.
System 100 further includes a retroreflector 106. A retroreflector is a type of surface with unusual reflectance characteristics, namely that it reflects light mainly back in the direction from which it came. This makes retroreflecting surfaces appear much brighter than matte surfaces, if the light source is located very near to the viewer, and dark otherwise. Retroreflecting surfaces are often found on road markings and signs.
The system further includes a photodetector 104 located adjacent to the light source 101. In one embodiment of the invention, a light blocking baffle (not shown) is located between the light source 01 and the photodetector 104 to prevent the photodetector 104 from detecting the light beam 120 prior to being reflected by the retroreflector 106. The light blocking baffle prevents scattered light from being detected by the photodetector 104. It is appreciated that any number of devices could be used in accordance with embodiments of the present invention to block unwanted light from the photodetector 104.
For example, in another embodiment of the invention, the photodetector 104 includes a bandpass light filter (not shown) for filtering wavelengths of light other than the wavelength band generated by the light source 101. The light filter makes the system 100 more robust against ambient light sources (e.g., natural light and other light sources around system 100). In one embodiment of the invention, the light filter is an optical film placed over the optical eye of the photodetector, however, it is appreciated that any number of light filters could be used in accordance with embodiments of the present invention. In one embodiment of the invention, the light source 101, light blocking baffle and photodetector 104 are coupled together forming an optoelectronic unit.
In one embodiment of the invention, the light source 101 is aimed across a gap to be protected (e.g., a door, window, etc.). The light beam provides a security threshold separating the first area (A) 110 from the second area (B) 112. The photodetector 104 detects the reflected light beam 125 and generates a signal in response to detecting a disruption in the light beam. In one embodiment of the invention, a processor 108 is coupled to the photodetector. In one embodiment of the invention, the photodetector signals a disruption when either the light beam 120 or the reflected light beam 125 is broken.
In one embodiment of the invention, the processor 108 is coupled to the light source in addition to the photodetector 104. In this embodiment of the invention, characteristics of the light source are modulated (e.g., amplitude or frequency of the generated light beam) to further decrease problems associated with ambient light and/or attempts to overcome the system by intruders.
In one embodiment of the invention, the optoelectronic units 210 generate a light beam 120 which is aimed at a retroreflector 202 located on the opposite end of the optoelectronic units 210. In one embodiment of the invention, the retroreflector 202 is a strip of retroreflective material. In another embodiment of the invention, the retroreflector 202 comprises a plurality of individual retroreflectors, such as a linear array of retroreflectors. In this embodiment of the invention, the generated light is reflected 125 back to the optoelectronic units 210 creating a plane of light. The plane of light (or light pane) is effectively a boundary separating a first area from a second area. For example, in the case of a window opening, the light plane separates the inside of the structure (e.g., behind the window) from the outside of the structure (e.g., in front of the window).
In one embodiment of the invention, a three-dimensional array (comprising a plurality of light beams) of light is generated. In this embodiment of the invention, a direction of entry can be determined by processor 108 based on which of the light beams is broken. For example, if a light beam on the outside plane of the three-dimensional light array is broken, it can be determined that the entry is from the outside.
If a light beam on the inside plane of the three-dimensional light array is broken, the entry is determined to be from the inside. In this embodiment of the invention, one can protect a point of entry such as a window and have the freedom to put a head out for fresh air without setting off an alarm. When an object enters from the outside, the alarm would be activated. In one embodiment of the invention, the processor 108 can determine statistics such as velocity, direction of entry, etc. of an object interrupting the light plane.
At step 302, method 300 includes generating a plurality of light beams at a plurality of light sources, the light beams forming a light plane separating a first area from a second area. In one embodiment of the invention, the light beams include an infrared wavelength. In one embodiment of the invention, the light sources include an LED.
At step 304, method 300 includes reflecting the plurality of light beams back to the individual light sources by a retroreflector positioned across from said linear array of individual light sources. In one embodiment of the invention, the retroreflector includes a plurality of individual retroreflectors. In another embodiment of the invention, the retroreflector is a strip (or any other shape) of retroreflective material.
At step 306, method 300 includes detecting the light beams after reflection at a plurality of photodetectors positioned adjacent to the light sources. In one embodiment of the invention, the photodetectors and light source are part of an optoelectronic unit. In one embodiment of the invention, a light-blocking baffle is positioned to block the light beam from the photodetector prior to being reflected by the retroreflector. In one embodiment of the invention, the photodetector comprises a bandpass filter for blocking transmission of light wavelengths except for the wavelength band generated by the light source.
In one embodiment of the invention, a characteristic of the light beam is modulated to prevent ambient light from interfering with the functionality of the photodetector. In one embodiment of the invention, modulation of the light beam characteristics makes it difficult for a would-be intruder to compromise the system and enter undetected.
At step 308, method 300 includes detecting an interruption in one of the plurality of light beams. In one embodiment of the invention, a direction and/or location of entry can be determined based on which of the plurality of light beams is disrupted and/or the order in which the different light beams are interrupted. At step 310, method 300 includes generating an alarm signal in response to the interruption.
It is appreciated that the linear array (e.g., array 420 and/or array 430) of optoelectronic units could be arranged to run parallel to the length of the corridor 401, located close to the floor of the corridor 401. If they are low enough to the floor to prevent someone crawling underneath and close enough together to prevent someone from stepping in between them, such an array can also be used to detect travel in the wrong direction.]
Referring now to
Computer system 500 includes an address/data bus 501 for communicating information, a central processor 502 coupled with bus 501 for processing information and instructions, a volatile memory unit 503 (e.g., random access memory, static RAM, dynamic RAM, etc.) coupled with bus 501 for storing information and instructions for central processor 502 and a non-volatile memory unit 504 (e.g., read only memory, programmable ROM, flash memory, EPROM, EEPROM, etc.) coupled with bus 501 for storing static information and instructions for processor 502. Computer system 500 may also contain an optional display device 506 coupled to bus 501 for displaying information to the computer user. Moreover, computer system 500 also includes a data storage device 505 (e.g., disk drive) for storing information and instructions.
Also included in computer system 500 of
Embodiments of the present invention, a system and method for detecting entry of an object from a first area to a second area have been described. While the present invention has been described in particular embodiments, it should be appreciated that the present invention should not be construed as limited by such embodiments, but rather construed according to the following Claims.
The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.
