Abstract:
An interoperable vacuum measuring device is presented, which automatically adjusts to one of two or more vacuum sensors having different electrical characteristics. The interoperable vacuum measuring device in a first step detects which type of vacuum sensor it is connected to. In a second step it controls and evaluates the vacuum sensor, using control parameters determined in response to the detection of the first step. 
     Detection of a vacuum sensor type is achieved by measuring the electrical resistance between any two pins of a vacuum sensor&#39;s connector and comparing the measured resistance values with stored resistance values of known vacuum sensors. 
     Further, a vacuum measuring device is presented, which automatically identifies a vacuum sensor, and associates a vacuum pressure measurement with a vacuum sensor. The identification of a vacuum sensor is facilitated by an identification disk, which is placed onto and operatively connected to the male terminals of a vacuum sensor&#39;s connector.

Description:
CLAIM FOR PRIORITY 
       [0001]    This application claims priority of U.S. provisional patent application No. 61/294,510, filed Jan. 13, 2010, which is hereby incorporated by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention generally relates to vacuum measuring devices, and more particularly, to vacuum measuring devices with interchangeable vacuum sensors. 
       BACKGROUND OF THE INVENTION 
       [0003]    Vacuum measuring systems are widely used and typically comprise a vacuum sensor and a vacuum measuring device. The vacuum measuring device controls and reads the vacuum sensor. The vacuum sensor is typically permanently attached to a vacuum container using an air-sealed interface. The vacuum measuring device may be portable and carried between several vacuum containers, especially if continuous monitoring of the vacuum container is not required. The vacuum sensor is typically connected to the vacuum measuring device using a plug-in connector. Commonly used vacuum sensors are thermocouple gauge tubes. 
         [0004]    While several different vacuum sensor manufacturers utilize the same electrical connector geometry, their vacuum sensors differ in their electrical characteristics and connector pinout. Therefore, vacuum sensors and vacuum measuring devices have to be matched, so that the correct vacuum measuring device is used with each vacuum sensor. This requires a user of vacuum measuring equipment to purchase matching vacuum measuring devices for each vacuum sensor. It also creates a risk of accidentally connecting the wrong vacuum measuring device to a vacuum sensor, which may lead to incorrect measurements, or may even cause damage to the vacuum sensor or the vacuum measuring device. 
         [0005]    Vacuum measuring devices are known, which support two different vacuum sensor models by providing sockets for two different connectors, one for each sensor model. Those measuring devices however require an operator to identify the sensor model to be connected and select the correct socket for the sensor, still leaving the opportunity for operator error and accidental wrong connections. 
         [0006]    Where vacuum pressure in two or more containers is measured using the same vacuum measuring device it is desirable to automatically detect, which vacuum container, respectively vacuum sensor, the measuring device is connected to. However, current vacuum sensors provide no means for identifying a particular sensor, so that an operator has to rely on a separate process to identify the vacuum container, to which a vacuum sensor is connected. This allows for potential errors, in which a vacuum pressure measurement is incorrectly associated with the wrong vacuum container. 
         [0007]    Therefore, in light of the problems associated with existing approaches, there is a need for improved vacuum sensing devices, which are interoperable with vacuum sensors from different manufacturers, those sensors having different electrical characteristics and pinouts. It is further desirable to automatically identify a vacuum sensor, in order to associate a vacuum pressure measurement with a vacuum container. 
       SUMMARY OF THE INVENTION 
       [0008]    In one aspect of the present invention an interoperable vacuum measuring device is presented, which automatically adjusts to one of two or more vacuum sensors having different electrical characteristics. The interoperable vacuum measuring device in a first step detects, which type of vacuum sensor it is connected to. In a second step it controls and evaluates the vacuum sensor, using control parameters determined in response to the detection of the first step. 
         [0009]    A vacuum sensor may be identified by measuring the electrical resistances between its connector pins. A particular vacuum sensor type and manufacturer may then be determined through a lookup table, which correlates the measured resistance values with a particular vacuum sensor type and manufacturer. The lookup table may further comprise information about the sensor&#39;s electrical characteristics, e.g. its supply voltage, heating current, pinout, and the correlation of output voltage and vacuum pressure (the vacuum sensor characteristic line). The lookup table may comprise data for two or more vacuum sensors. The values contained in the lookup table may be empirically gathered data, which may be determined by analyzing and measuring an exemplary sensor. 
         [0010]    While vacuum sensors of different manufacturers may use a common connector, their pinout may be different. Different pinouts cause the resistance between two pins in the connector to change, thereby supporting the discrimination of sensors in the lookup table. 
         [0011]    In a further aspect of the present invention a vacuum measuring device is presented, which automatically identifies a vacuum sensor, and associates a vacuum pressure measurement with a vacuum sensor. The identification of a vacuum sensor is facilitated by an identification disk, which is placed onto and operatively connected to the male terminals of a vacuum sensor&#39;s connector. The identification disk has a body which is favorably shaped like the connector. Holes are arranged in the body to allow the pins of the vacuum sensor to protrude the identification disk. The disk is thin enough to fit between the sensor&#39;s connector and the measuring device&#39;s socket without affecting the electrical connection between the sensor and the measuring device. Contacts are located in at least two of the disk&#39;s holes, electrically connecting the protruding terminals with at least one identifiable electric or electronic component inside the identification disk. The identifiable electric or electronic component inside the identification disk may e.g. be a resistor having an identifiable value or a non-volatile memory device comprising an identification number. The at least one electric or electronic component may also be a binary-coded conductor arrangement which may e.g. be coded by lasers. It may further be a set of switches, ROM, PROM, EPROM or FLASH memories or other electronic storage media. 
         [0012]    When a vacuum measuring device is attached to a vacuum sensor having an identification disk, a microcontroller within the vacuum measuring device becomes operatively connected to the identifiable electric or electronic component in the identification disk. The microcontroller identifies the identifiable electric or electronic component, e.g. by determining the resistance value of an identifiable resistor or reading an identification number out of an identifiable electronic memory. The identification of a particular vacuum sensor may be used to associate vacuum pressure measurements with a particular vacuum sensor, and thus a particular vacuum container. The microcontroller in the measuring device may comprise an electronic memory and store vacuum measurement values, time stamps, operator identification and other data in association with a vacuum sensor identification. The electronic record may also be transferred to a computer system, considerably simplifying task including monitoring of equipment, quality assurance and documentation. 
         [0013]    A writable electronic memory, e.g. an EPROM element, can be used as the identifiable electronic component, so that the time and value of the last vacuum pressure measurement can be stored inside the identification disk. This allows an immediate comparison between the last and the current vacuum pressure value. A rise in vacuum pressure, for example, due to leaks, can thus be recognized immediately without need to refer to any data stored outside the vacuum sensor and its identification disk. 
         [0014]    In a further embodiment, the measuring device or the code disk is equipped with a radio module and at predetermined time intervals or continuously can wirelessly transmit the measured values together with the identification data to a central unit or wirelessly read the sensor identification, e.g., via an RFID (radio frequency identification) tag present in the disk. 
         [0015]    The following detailed description of the invention is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background of the invention or the following detailed description of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is an illustration showing multiple vacuum sensors, an identification disk, and a schematic vacuum measuring device. 
           [0017]      FIG. 2  shows an exemplary circuit diagram of an interoperable vacuum sensing device. 
           [0018]      FIG. 3  shows an exemplary identification disk for use with vacuum sensors. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    Referring to  FIG. 1 , an exemplary embodiment in which aspects of the present invention are advantageously practiced is illustrated generally. Several vacuum sensors ( 110 ,  120 ,  130 ,  140 ) are shown, which utilize a common connector layout. An identification disk  180  is provided, which can be placed between the male connector  100  of vacuum sensor  110 ,  120 ,  130  or  140  and socket  150  of a vacuum measuring device  160 . Socket  150  is connected to a pig-tail  151 , which is terminated in vacuum measuring device  160 . Vacuum measuring device  160  is operatively connected to one of the vacuum sensors  110 ,  120 ,  130  or  140  trough connector  100 , when plugged into socket  150 . Vacuum measuring device  160  may comprise a display for displaying the vacuum pressure. Vacuum measuring device  160  may also comprises an output (not shown), which is configured to provide a vacuum pressure signal. The output may be any form of communicable electrical signal, e.g. a variable voltage, variable current, pulse width modulated signal or a serial or parallel digital communication signal. 
         [0020]    Identification disk  180  mimics the geometry of and can be placed onto connector  100 . Identification disk  180  comprises holes  181 - 188 , through which the male terminals  101 - 108  of connector  100  protrude. A center hole  189  is provided, which allows the center pin  109  of connector  100  to protrude. Center hole  189  also provided rotational alignment between identification disk  180  and connector  100 , by engaging recess  190  of center hole  189  with guide pin  191  of center pin  109 . 
         [0021]    Identification disk  180  may be placed onto connector  100  of vacuum sensor  110 ,  120 ,  130  or  140 . Identification disk  180  is held in place by interference fit between male terminals  101 - 108  and holes  181 - 188 , center pin  109  and center hole  189 , or both. Identification disk  180  is thin, so that terminals  101 - 108  protrude identification disk  180  far enough to firmly engage the female pins of socket  150 , when connector  100  is plugged into socket  150 . 
         [0022]      FIG. 3  shows a plan view of and a section through an identification disk  31 . Holes  32  are located such that the male terminals of a vacuum sensor can protrude identification disk  31  and enclose them in a resilient manner. A central recess  33  is provided for guide pins of the connector with guide key. 
         [0023]    Identification disk  31  may be a multilayer circuit boards with corresponding recesses and contain an integrated storage element or identification element  34 . Identification disk  31  is preferably made of FR4, but any other material known in the art of manufacturing circuit boards may be used. Identification disk  31  is preferably less than 3 mm thick. Identification element  34  may e.g. be a resistor, EPROM, or other identifiable component connected by conductor paths to contacts  35 ,  36  in holes  32 . A connected measuring device has access to the identification element or storage element in the identification disk through the corresponding contacts  35 ,  36  in holes  32 . Contacts  35  is an exemplary contact using form fit to establish an electrical connection with the protruding male terminal in hole  32 . 
         [0024]    An exemplary method of using a vacuum sensor with attached identification disk comprises the following steps:
       Placing an identification disk  180  onto the connector  100  of a vacuum sensor ( 110 ,  120 ,  130 ,  140 ). This step is performed only once, whereas some or all of the following steps are performed each time a vacuum measurement is taken.   Attaching the socket  150  of a vacuum measuring device  160  to a vacuum sensor ( 110 ,  120 ,  130 ,  140 ).   Switching on vacuum measuring device  160 .   Identifying the vacuum sensor ( 110 ,  120 ,  130 ,  140 ).   Reading the sensor number of vacuum sensor ( 110 ,  120 ,  130 ,  140 ).   Reading of the last measurement date stored in the coding disk  180 .   Reading of the last measured value stored in the coding disk  180 .   Measuring vacuum pressure sensed by the vacuum sensor ( 110 ,  120 ,  130 ,  140 ).   Storing the current measured value in the identification disc  180 .   Storing the current measurement date in the identification disc  180 .   Optionally, transmitting the measured data by radio (e.g., ZigBee, WLAN, RFID)   Optionally battery operated push-on module with radio, which, e.g., transmits one measured value daily.   Switching off vacuum measuring device  160 .   Removing the socket adapter  150  from vacuum sensor ( 110 ,  120 ,  130 ,  140 ).       
 
         [0039]    Referring now to  FIG. 2  an exemplary electric circuit diagram according to an aspect of the present invention is illustrated generally. Four electrically distinct vacuum sensors  210 ,  220 ,  230  and  240  are shown. Vacuum sensors  210 ,  220  and  230  utilize a different connector pinout. For example, vacuum sensor  230  is powered through pins  1  and  8 , while pin  5  serves as a signal pin. In contrast, vacuum sensor  210  is powered trough pins  3  and  7 , while pins  4  serve as a signal pin, and pin  6  as a ground reference. Vacuum Sensors  230  and  240  have the same pinout but differ in the resistance values of the internal connections. Vacuum sensors  210 ,  220 ,  230  and  240  may be thermocouple gauge tubes, and exhibit different electrical characteristics. 
         [0040]    Each of the sensors  210 ,  220 ,  230 , or  240  can be connected to the socket  250 . Socket  250  comprises 8 socket pins, labeled PIN 1  through PIN 8 . The pins of the socket  250  are connected through cable  251  to an electronic circuit in the vacuum measuring device  160 . Vacuum measuring device  160  comprises four multiplexers  271 ,  272 ,  273  and  274 . Each multiplexer selectively connects an input X with one output X 0  through X 7 . Which output X 0  through X 7  input X is connected to is controlled by control inputs A, B, C, and INH. Control inputs A, B, C, and INH are operatively connected to a microcontroller  261 . Microcontroller  261  comprises an analog-digital (A/D) converter and electronic memory. Microcontroller  261  is operatively connected to an adjustable current or voltage source  260 . Vacuum measuring device  160  further comprises an amplifier arrangement  280 , a display unit (not shown), an output unit (not shown) and an input unit (not shown). Microcontroller  261  can establish various connection configurations, in which each PIN 1  through PIN 8  of socket  250  can be connected to either adjustable current or voltage source  260 , to ground, or to amplifier arrangement  280 . Each connection configuration is a unique combination of connecting the adjustable current or voltage source  260  and ground to the more socket pins PIN 1  through PIN 8  of socket  250 . Multiplexer  272  establishes an electrical return path for current through vacuum sensors  210 ,  220 ,  230  or  240 . While this return path is shown to be ground, it should be understood that a different return potential may be used. 
         [0041]    Each PIN 1 - 8  of socket  250  is wired in parallel to each multiplexer  271 ,  272 ,  273  and  274 . Each multiplexer  271 ,  272 ,  273 , and  274  is operatively connected to all 8 socket pins of socket  250 . 
         [0042]    Multiplexer  271  is configured to selectively connect adjustable current or voltage source  260  to any of pin  1 - 8  of socket  250 . Adjustable current or voltage source  260  may be a voltage controlled current source, which is operatively connected to and controlled by microcontroller  261 . It may more specifically be a current source suitable to power a thermocouple gauge tube. Similarly, multiplexer  272  can selectively connect a current sink or ground to any of pins  1  through  8  of socket  250 . By selecting the appropriate outputs of multiplexers  271  and  272  any vacuum sensor  210 ,  220 ,  230  or  240  can be powered by adjustable current or voltage source  260 , irrespective of the pinout of the vacuum sensor. Multiplexer  271  operates as a supply pin selector, which operatively connects current or voltage source  260  with any one of PIN 1  through PIN 8  of socket  250 . Multiplexer  272  operates as a return pin selector, establishing a return path for current from vacuum sensor  210 ,  220 ,  230  or  240  through any one of PIN 1  through PIN 8 . Multiplexers  273  and  274  operate as signal pin selectors, connecting any one of PIN 1  through PIN 8  to amplifier  280 . While multiplexers  271 ,  272 ,  273 , and  274  are shown as four integrated circuits they may also be combined into fewer than four components, or separated into more than four components. Multiplexers  271 ,  272 ,  273 , and  274  may also be replaced by any other electronically controlled switching device known in the art. 
         [0043]    In an exemplary embodiment vacuum measuring device  160  is configured to automatically detect, which type of vacuum sensor  210 ,  220 ,  230  or  240  is connected to socket  250 . Automatic detection is achieved while in a detection mode by sequentially connecting adjustable current or voltage source  260  and ground  263  to different pins of socket  250  through multiplexers  271  and  272 . Adjustable current or voltage source  260  is controlled to establish a predetermined evaluation current, e.g. 1 mA. The output voltage of output  262  of adjustable current source  260  is read by an A/D converter input of microcontroller  261 . Microcontroller  261  calculates the electrical resistance between output  262  and ground  263  by dividing output voltage  262  by the selected adjustable evaluation current value. The calculated electrical resistance between one or more pairs of pins of a vacuum sensor is indicative of its type. An electronic memory within microcontroller  261  comprises a table of predetermined resistance values with associated multiplexer settings for multiplexers  271  and  272 . 
         [0044]    The following example describes the automatic detection of a vacuum sensor  210  (type D): First, microcontroller  261  configures multiplexer  271  to connect adjustable current source  260  to pin  3  of socket  250 . Microcontroller  261  configures multiplexer  272  to connect ground  263  to pin  7  of socket  250 . Next, microcontroller  261  configures adjustable current source  260  to a predetermined current. The predetermined evaluation current flows from adjustable current source  260  through multiplexer  271  and pin  3  of socket  250  into the vacuum sensor  210 . It returns through pin  7  of socket  250  and multiplexer  272  to ground  263 . Microcontroller  261  calculates the resistance between adjustable current source  260  and ground  263  by measuring the voltage of output  262  and dividing it by the predetermined evaluation current. In a further step microcontroller  261  compares the calculated electrical resistance with a stored value of typical resistances for a vacuum sensor  210 . If the calculated resistance falls within the range that is typical for type D vacuum sensors microcontroller  261  determines, that a type D vacuum sensor is connected to socket  250 . The calculated resistance equals the internal resistance of vacuum sensor  210  between pin  3  and pin  7  plus contact resistances, wiring resistance and resistance of multiplexers  271  and  272 . Microcontroller  261  is programmed to consider for the total resistance between current source  260  and ground  263 . 
         [0045]    In some instances measuring the resistance between any two pins of a vacuum sensor may not be sufficient to identify the type of vacuum sensor. Two vacuum sensors with identical pinout and similar internal resistances may be distinguished by evaluating the polarity of thermoelectric voltage  290 . 
         [0046]    After a type of vacuum sensor has been identified, microcontroller  261  switches into an operating mode and controls multiplexers  273  and  274  to connect amplification circuit  280  to the measuring element within vacuum sensor  210 ,  220 ,  230  or  240 . The correct settings for multiplexer  273  and  274  may be stored in the electronic memory of microcontroller  261 . Generally, the pinout information for various vacuum sensors may be associated with empirically collected internal resistance values between selected pins for each vacuum sensor. If, per the example above, a type D vacuum sensor has been detected microcontroller  261  controls multiplexer  273  to connect its input X 3  (pin  4 ) to its output X. Microcontroller  261  controls multiplexer  274  to connect its input X 5  (pin  6 ) to its output X. Thereby the sensor output on pins  4  and  6  of vacuum sensor  210  are operatively connected to amplification circuit  280  in vacuum measuring device  160 . Amplification circuit  280  feeds thermocouple voltage output  290 . 
         [0047]    For embodiments with limited flexibility multiplexers  273  and  274  may be omitted, limiting the vacuum measuring device  160  to be operative only with vacuum sensors that use common pinout of their measuring outputs. Alternatively, multiplexers  273  and  274  may be replaced by a limited number of switches, limiting the vacuum measuring device  160  to be operative only with vacuum sensors that use a pinout adequate to the possible switch positions. 
         [0048]    Microcontroller  261  may be programmed to automatically identify a vacuum sensor type that is connected to socket  250  by executing the following steps:
   1. Controlling adjustable current source  260  to a low evaluation current (e.g. 0.1-3 mA). The low evaluation current is selected such, that any vacuum sensor attached to socket  250  will not be damaged, even if the evaluation current is applied in a manner inconsistent with the intended use of the vacuum sensor. This may e.g. include current flow through the thermoelectric sensing connections of a thermocouple vacuum gauge.   2. Measuring the output voltage of adjustable current source  260  while multiplexers  271  and  272  are inactive. This step may optionally be omitted, since the voltage measured in this step may equal the supply voltage of the adjustable current source and therefore be known.   3. Selecting an output X 0  . . . X 7  of multiplexer  271  by controlling its control lines “IO_O,” “IO — 1” and “IO — 2”.   4. Selecting an output X 0  . . . X 7  of multiplexer  272  by controlling its control lines “IO — 3,” “IO — 4” and “IO — 5”. The selected output X 0  . . . X 7  of multiplexer  272  should be different than the selected output X 0  . . . X 7  of multiplexer  271  to avoid causing a short of the adjustable current source to ground.   5. Activating multiplexers  271  and  272  by applying a “heating” activation signal. The “heating” signal may be applied to an inhibit entry of the multiplexer.   6. Measuring the output voltage of adjustable current source  260 .   7. Calculating the current flow through the selected pins of the vacuum sensor. The current flow can be calculated as a function of the evaluation current selected in step 1 and the output voltage measured in step 6. If the output voltage measured in step 6 is essentially the same as the output voltage measured in step 2 no current flows through the vacuum sensor attached to socket  250 .   8. Repeating steps 4 through 7 for all possible multiplexer settings.   9. Comparing the current flows calculated in step 7 for given multiplexer settings to a table of known current flows for the same multiplexer settings. The table of known current flows may have been empirically determined by measuring various types of vacuum sensors.   10. Determining the type of vacuum sensor connected to socket  250  in response to the comparison of step 9.   11. Selecting an output X 0  . . . X 7  of multiplexer  271  and an output X 0  . . . X 7  of multiplexer  272  in response to the type determination of the attached vacuum sensor in step 10. The selection is made such that the vacuum sensor is operated according to the intended use for a sensor of the determined type as provided by its manufacturer (stored in a table).   12. Controlling adjustable current source  260  to an operating current. The appropriate operating current may be selected from a lookup table. The lookup table comprises appropriate operating currents for each vacuum sensor type determined in step 10.   13. Selecting an input X 0  . . . X 7  of multiplexer  273  and an input X 0  . . . X 7  of multiplexer  274  by controlling their respective control inputs “IO — 6 through IO — 11”. The settings for multiplexers  273  and  274  may be selected from the lookup table. The measuring output of vacuum sensor is operatively connected through multiplexers  273  and  274  to an amplification circuit  280 .   12. Measuring the vacuum pressure surrounding the vacuum sensor. Vacuum pressure may be measured by alternating between a heating and a measuring cycle. During a heating cycle activating multiplexers  271  and  272  are activated by applying a heating signal applied to the multiplexers&#39; inhibit input. During a measuring cycle multiplexers  273  and  274  are activated by applying a measuring signal to the multiplexers&#39; inhibit input.   
 
         [0063]    In variation to the exemplary method described above step 8 may be slightly modified. Instead of analyzing all possible settings of multiplexers  271  and  272  steps 4 through 7 may be repeated following a sequence of predetermined multiplexer settings until the vacuum sensor attached to socket  250  has been unambiguously identified. 
         [0064]    While the invention has been described with reference to vacuum sensors and specifically to thermocouple gauge tubes it may be beneficially applied to many other sensors, which need not be based on thermocouple technology. 
         [0065]    While the present invention has been described with reference to exemplary embodiments, it will be readily apparent to those skilled in the art that the invention is not limited to the disclosed or illustrated embodiments but, on the contrary, is intended to cover numerous other modifications, substitutions, variations and broad equivalent arrangements that are included within the spirit and scope of the following claims.