Abstract:
An environmental monitoring system is disclosed including a plurality of sensors, a plurality of sensor modules each electrically connected to one of the plurality of sensors for generating a ID signal that uniquely identifies the one sensor electrically connected thereto, a plurality of first electrical connectors each electrically connected to one of the sensor modules and a central monitoring unit that includes a plurality of second electrical connectors for connection with the first electrical connectors, a CPU for receiving the ID signals via the first and second electrical connectors for identifying each of the sensors in response to the received ID signals and for configuring operating parameters for each of the identified sensors, and a storage medium for storing sensor data corresponding to the sensor signals. Other elements of the monitoring system can include a power supply, at least one input/output module and calibration ports.

Description:
This application claims the benefit of U.S. Provisional Application No. 60/300,590, filed Jun. 22, 2001, and entitled Environmental Monitoring System with Smart Sensors. 

   FIELD OF THE INVENTION 
   This invention relates generally to an environmental monitoring system (EMS) for clean room operation and contamination control, and more particularly to a system that automatically integrates a wide variety of environmental sensors of different types. 
   BACKGROUND OF THE INVENTION 
   It is well known to use sensors to monitor the environmental conditions in clean rooms that are used to make, for example, semiconductor devices. Numerous environmental conditions must be maintained, and therefore monitored, to ensure certain clean room specifications are met. Examples of such environmental conditions include temperature, relative humidity, air velocity, differential pressure between clean room areas, airborne particle counts, etc. 
   Clean room environmental sensors serve several purposes: to create a record of the clean room conditions, to sound an alarm should any environmental parameter fall outside a specified range, and to provide feedback for the systems used to maintain the desired clean room conditions. Typically, a large number of such sensors are used in any given clean room environment, especially if a dozen or more sensors are used to monitor mini-environments at various locations within the clean room. Each such sensor requires it own power source, user interface, and separately configured control device that determines and allows the user to adjust the sensor&#39;s operating parameters (e.g. output range scale, set points, calibration, sampling interval, high/low alarm limits, etc.). Thus, installation, configuration and operation of multiple sensor systems can be complicated, time consuming, expensive and redundant. 
   There is a need for a centralized environmental monitor system that is compatible with and can automatically configure and control a number of sensors and sensor types. 
   SUMMARY OF THE INVENTION 
   The present invention solves the aforementioned problems by providing an environmental monitoring system that automatically detects and performs all necessary setup and configuration steps when a sensor is plugged into any of the sensor ports. Operation and monitoring of multiple sensors is performed using a single control device. 
   Broadly stated, the invention is directed to an environmental monitoring system, including a plurality of sensors, a plurality of sensor modules each electrically connected to one of the plurality of sensors for generating a ID signal that uniquely identifies the one sensor electrically connected thereto, a plurality of first electrical connectors each electrically connected to one of the sensor modules and a central monitoring unit that includes a plurality of second electrical connectors for connection with the first electrical connectors, a CPU for receiving the ID signals via the first and second electrical connectors for identifying each of the sensors in response to the received ID signals and for configuring operating parameters for each of the identified sensors, and a storage medium for storing sensor data corresponding to the sensor signals. 
   Other elements of the monitoring system can include a power supply for supplying operating power to the sensors via the plurality of first and second electrical connectors, at least one input/output module connected between the second electrical connectors and the CPU for communicating the sensor signals and ID signals received from the sensors and sensor modules to the CPU, at least some of the sensor signals being analog and others of the sensor signals being digital, and calibration ports for the sensor modules for transmitting calibration signals to and from the sensor connected thereto. 
   Other objects and features of the present invention will become apparent by a review of the specification, claims and appended figures. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a block diagram of the environmental monitoring system of the present invention. 
       FIG. 2  is a block diagram of the central monitoring unit of the present invention. 
       FIG. 3  is a block diagram of the sensor and sensor module of the present invention. 
       FIG. 4  is a block diagram of the integral sensor and sensor module of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The present invention is an integrated, stand-alone clean room environmental monitoring system that integrates sensor configuration, operation and control using a single central unit that provides plug-and-play support for different types of sensors. 
   The monitoring system of the present invention is shown in  FIG. 1 , and includes a central monitoring unit  10 , a plurality of sensor modules  12  and a plurality of sensors  14 . 
   The central unit  10  is better shown in  FIG. 2 , and includes a central processing unit (CPU)  20  that is connected to a visual display  22 , input keys  24 , a storage medium  26 , a power supply  28 , and an Ethernet hub  30 . Ethernet hub  30  is connected to a plurality of input/output (I/O) modules  32 , which in turn are connected to a plurality of external electrical connectors  34 . The power supply  28  provides one or more voltages (e.g. 5V, 12V, and/or 24V) not only to provide electrical power to operate the central unit components, but also to operate the sensors  14  and the sensor modules  12 . 
   Visual display  22  and input keys  24 , which allow the user to view and manipulate the operation of the monitoring system, can be separate elements as shown in  FIG. 2 , or can be combined together as a liquid crystal display (LCD) with pressure sensitive “touch screen” input keys. The storage medium  26  can be any digital information storage device (e.g. disc drive, RAM, non-volatile memory, etc.) that can temporarily or permanently store sensor data. 
   Each of the environmental sensors  14  is connected to one of the external connectors  34  of the central unit  10  via a sensor module  12  as shown in FIG.  3 . Each sensor module  12  includes a sensor port  36 , an identification (ID) circuit  38 , and a module port  40 . Sensors  14  can be any conventional sensor device that measures an environmental parameter, such as air flow, humidity, differential pressure, temperature, airborne particle count, etc. Each such sensor  14  includes its own standard sensor cable  42  and terminal connector  44  thereon that connects to a compatible sensor port  36 . Different sensors  14  may have different types of terminal connectors  44 , and thus the sensor module associated therewith must have a sensor port  36  that is compatible with that terminal connector. A module cable  46  connects between the module  12  and central unit  10 , with a first terminal connector  48  at one end that connects with module port  40  and a second terminal connector  50  that connects with one of the external connectors  34 . As explained further below, module cable  46  transmits power to the sensor  12  and sensor module  14 , and transmits ID information and sensor data to the central unit  10 . Calibration ports  41  can be included in sensor module  12  for those sensors that can be or need to be calibrated remotely, where a calibration signal is applied to the sensor, and a calibration return voltage is then measured to ensure proper calibration. 
   The present invention utilizes smart sensor technology whereby the system automatically identifies and configures sensors that are plugged into external connectors  34 . Specifically, once a sensor  14  and sensor module  12  are connected to the central unit  10  as shown in  FIG. 3 , power is supplied via module cable  46  from the central unit  10  to the sensor module  12  and to sensor  14  to operate both devices. The ID circuit  38  is set to return an ID voltage or current signal back to the central unit  10  via cable  46  that uniquely identifies the sensor  14  connected to the module  12 . The ID signal could be a simple analog signal that is generated by converting the supply voltage from the central unit  10  into a unique ID voltage that corresponds to a particular sensor type. Alternately, the ID signal could be a more elaborate digital signal (e.g. using multiple signal lines to generate a unique combination of on/off or low/high states). Once the central unit  10  identifies the sensor type, it then automatically performs all the necessary setup and configuration of the operational parameters for the sensor, including scaling the output range of the sensor, setting any set points, establishing the sampling (data-logging) interval, setting high and low alarm limits, creating the proper graphical display for that specific data, etc. These operational parameters can be modified by the user after the sensor  14  is plugged into the central unit  10  via module  12  and identified, for true plug and play set-up and operation. 
   Once all the environmental sensors are connected to the central unit  10  via external connectors  34 , the system continuously monitors the output from these sensors and records the data therefrom on the storage medium  26 . The central unit  10  utilizes Ethernet and software protocols for component communication. A PC or network can be connected to the central unit via an Ethernet port  52  for remote monitoring and/or control, as well as for downloading the recorded data from the storage medium  26 . The user can operate and monitor all of the sensors, and can set/modify operating parameters (such as alarm limits and warning levels) for each of the sensors, using a single display  22  and set of input keys  24 . 
   It is desirable to make all the of the second terminal connectors  50  and external connectors  34  the same compatible type, such as CAT 5 or DB9, so that any sensor equipped with a sensor module  12  can be plugged into any of the external connectors  34  in a play-and-plug fashion. 
   The I/O modules  32  contain the appropriate circuitry (e.g. A/D and D/A converters, voltage supplies, etc.) to allow the CPU  20  to communicate with and operate the sensors identified as being connected to central unit  10 . Some clean rooms may utilize some sensors requiring an analog communications protocol (i.e. an analog I/O module  32 ), and other sensors requiring a digital communications protocol (i.e. a digital I/O module  32 ). In such a case, some of the I/O modules  32  and the external connectors  34  connected thereto are dedicated to only digital sensors, while the remaining I/O modules  32  and external connectors  34  are dedicated to analog sensors. Connectors  34 / 50  should then be keyed, labeled, modified or be of a different type to prevent analog sensors from being plugged into digital I/O modules, and vice versa. 
   If sensor port  36  and terminal connector  44 , and/or module port  40  and first terminal connector  48 , provide removable electrical connections, it is important to ensure that the type of sensor connected to the sensor module  12  matches the ID circuit  38  in that module so that the sensor is not improperly identified to the central unit  10 . Improper identification can be avoided by labeling or keying these connections. Alternately, these connections can be hardwired, non-removable connections (where connectors  44  and  48  are simply hardwired electrical connections). 
   Module  12  can be located anywhere between terminal connector  50  and sensor  14 . In fact, sensor module  12  can be integrally formed within the housing of connector  50  or sensor  14 . For example,  FIG. 4  shows in diagram form a standard sensor that has been modified according to the present invention. The sensor&#39;s standard communications and power cords have been removed, and a sensor module  12  (e.g. formed on a small PC board) has been installed inside the housing  54  of the sensor assembly and connected to the sensor  14 , with the module cable  40  extending from the sensor housing  54 . The sensor&#39;s power and data signals are supplied and communicated through the sensor module  12  and module cable  46 . In most cases, the only outwardly visible change to the standard sensor device will be a different cord extending from the sensor housing, which terminates in an electrical connector  50  compatible with external connectors  34 . However, the embedded sensor module  12  inside provides operating power to the sensor, and ID and data signals back to the central unit  10  for proper sensor identification and operation. 
   Some of the sensors contemplated for use with the present invention include solid state air velocity sensors, capacitive sensing differential pressure sensor, thin film capacitor relative humidity sensors, and platinum RTD temperature sensors. Because all the sensors plugged into central unit  10  are automatically identified, the CPU can also detect the absence of a particular sensor or sensor type. 
   The present invention provides a single central monitoring unit that automatically supplies all the power needed to operate the sensor devices in the clean room, identifies sensors that are connected to the system, configures appropriate operating parameters without operator intervention, and provides centralized simultaneous control, monitoring and recordation for the plurality of sensors and the data provided thereby. The CPU  20  generates the appropriate display of the data from the sensors on the visual display  22 . 
   It is to be understood that the present invention is not limited to the embodiment(s) described above and illustrated herein, but encompasses any and all variations falling within the scope of the appended claims. For example, while  FIG. 2  shows separate I/O modules  32  for each of the external connectors  34 , I/O modules  32  can be combined to each support a plurality of external connectors  34 . For permanent installations, some or all of the electrical connectors  34 / 50  could be permanent hardwire connections.