Measurement apparatus

• US 4,531,193 A
• Filed: 07/27/1982
• Issued: 07/23/1985
• Est. Priority Date: 07/30/1981
• Status: Expired due to Term

• Current Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Original Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Inventors: Yasuhara, Takeshi, Nabeta, Eiichi
• Primary Examiner(s): Wise, Edward J.
• Application Number:
  US06/402,377
• Time in Patent Office: 1,092 Days
• Field of Search: 364/551, 364/550, 364/552, 364/555, 364/484, 364/492, 364/556, 364/557, 364/558, 364/510, 377/11, 377/19, 377/21
• US Class Current: 702/183
• CPC Class Codes: G01D 5/248 by varying pulse repetition frequency
• CPC Class Codes: G01L 9/12 by making use of variations in capacitance , i.e. electric circuits therefor
• CPC Class Codes: G01R 19/252 using analogue/digital converters of the type with conversion of voltage or current into frequency and measuring of this frequency
• CPC Class Codes: G01R 19/255 using analogue/digital converters of the type with counting of pulses during a period of time proportional to voltage or current, delivered by a pulse generator with fixed frequency
• CPC Class Codes: G06F 11/1608 Error detection by comparing the output signals of redundant hardware G06F11/1629, G06F11/1666 take precedence; error detection or correction in information storage based on relative movement between record carrier and transducer G11B20/18; checking static stores for correct operation G11C29/00; for logic circuits H03K19/003, H03K19/007; for pulse counters or frequency dividers H03K21/40
• CPC Class Codes: G06F 11/1625 in communications, e.g. transmission, interfaces
• CPC Class Codes: H03M 1/60 with intermediate conversion to frequency of pulses
• CPC Class Codes: H04B 10/524 Pulse modulation
• CPC Class Codes: H04B 10/69 Electrical arrangements in the receiver

Abstract

Disclosed is a measurement apparatus for measuring physical quantity, such as temperature, pressure etc., and providing corresponding measuremnt data suitable for transmission to a remote central location. The physical quantity being measured is first converted to a frequency signal, either directly by an appropriate transducer or by a combination of an appropriate transducer and appropriate converter. Counters are then used to convert the frequency signal to a corresponding digital quantity. An appropriately programmed digital processor is then used to perform processing operations on the digital quantity to derive the measurement data. In one embodiment, the apparatus includes an optical transceiver for converting the measurement data into corresponding optical signals for transmission via an optical fiber to a central processor. The optical transmission system between the measurement apparatus and the central processor includes provisions for facilitating the detection and diagnosis of failures in the optical components of the system. In another embodiment the measurement data is converted to corresponding current signals for transmission via a conducter to a remote central location.

Claims

1. An apparatus for measuring a physical quantity and providing corresponding measurement data comprising:

(a) transducer/converter means for converting a physical quantity being measured to a corresponding frequency signal having a frequency which is related to the physical quantity, the transducer/converter means including a transducer for converting the physical quantity being measured to a corresponding voltage signal, and a converter circuit having;

a capacitor, means including a constant current source for selectively charging and discharging the capacitor, comparator means for comparing a voltage across the capacitor with the voltage signal and for providing an output signal when the voltage across the capacitor is equal to or greater than the voltage signal, and monostable flip-flop means responsive to the output signal from the comparator means for providing a sequence of pulses having a frequency related to the voltage signal;

(b) counter means responsive to the frequency signal for providing a digital quantity related to the frequency of the frequency signal;

(c) digital processor means for performing predetermined processing operations on the digital quantity and providing measurement data corresponding to the physical quantity being measured; and

(d) a clock signal generator for providing a periodic sequence of clock pulses and wherein the counter means include a first counter circuit for counting the frequency cycles of the frequency signal commencing at the start of a measurement interval and for providing a counter ouput signal after a predetermined number of cycles have been counted and a second counter circuit for counting the sequence of clock pulses commencing at the start of the measurement interval and responsive to the counter output signal for stopping the counting of clock pulses and providing count data, and wherein the digital processor means is responsive to the counter output signal for reading the count data and for performing the predetermined processing operations thereon.

2. An apparatus for measuring a physical quantity and providing corresponding measurement data comprising:

(a) transducer/converter means for converting a physical quantity being measured to a corresponding frequency signal having a frequency which is related to the physical quantity, the transducer/converter means including a measuring resistor having a resistance related to the physical quantity being measured and a converter circuit having;

a capacitor, means for selectively charging the capacitor through the measuring resistor and for selectively discharging the capacitor, and monostable flip-flop means responsive to a voltage across the capacitor for providing a sequence of pulses having a frequency related to the resistance of the measuring resistor;

(b) counter means responsive to the frequency signal for providing a digital quantity related to the frequency of the frequency signal;

(c) digital processor means for performing predetermined processing operations on the digital quantity and providing measurement data corresponding to the physical quantity being measured; and

(d) a clock signal generator for providing a periodic sequence of clock pulses and wherein the counter means include a first counter circuit for counting the frequency cycles of the frequency signal commencing at the start of a measurement interval and for providing a counter output signal after a predetermined number of cycles have been counted and a second counter circuit for counting the sequence of clock pulses commencing at the start of the measurement interval and responsive to the counter output signal for stopping the counting of clock pulses and providing count data, and wherein the digital processor means is responsive to the counter output signal for reading the count data and for performing the predetermined processing operations thereon.

3. An apparatus for measuring a physical quantity and providing corresponding measurement data comprising:

(a) transducer/converter means for converting a physical quantity being measured to a corresponding frequency signal having a frequency which is related to the physical quantity, the transducer/converter means including a first and a second measuring capacitor, the capacitance of at least one of which is related to a mechanical displacement, and a capacitance-to-frequency converter circuit having;

means for selectively charging and discharging one or the other of the measuring capacitors, and monostable flip-flop means alternatively responsive to respective voltages across the measuring capacitors for alternatively providing a first sequence of pulses having a frequency related to the capacitance of the first measuring capacitor and a second sequence of pulses having a frequency related to the capacitance of the second measuring capacitor;

(b) counter means responsive to the frequency signal for providing a digital quantity related to the frequency of the frequency signal;

(c) digital processor means for performing predetermined processing operations on the digital quantity and providing measurement data corresponding to the physical quantity being measured; and

(d) a clock signal generator for providing a periodic sequence of clock pulses and wherein the counter means include a first counter circuit for counting the frequency cycles of the frequency signal commencing at the start of measurement interval and for providing a counter output signal after a predetermined number of cycles have been counted and a second counter circuit for counting the sequence of clock pulses commencing at the start of the measurement interval and responsive to the counter output signal for stopping the counting of clock pulses and providing count data, and wherein the digital processor means is responsive to the counter output signal for reading the count data and for performing the predetermined processing operations thereon.

4. An apparatus for measuring a physical quantity and providing corresponding measurement data comprising:

(a) transducer/converter means for converting a physical quantity being measured to a corresponding frequency signal having a frequency which is related to the physical quantity;

(b) counter means responsive to the frequency signal for providing a digital quantity related to the frequency of the frequency signal;

(c) digital processor means for performing predetermined processing operations on the digital quantity and providing measurement data corresponding to the physical quantity being measured; and

(d) a transceiver unit including an electrical-to-optical transducer for converting the measurement data into optical information for transmission to a central processor and an optical-to-electrical transducer for receiving optical information from the central processor and for converting the received optical information to electrical signals, wherein the digital processor means is responsive to a command signal from the transceiver unit corresponding to a command signal from the central processor specifying a measurement operation for performing predetermined processing operations corresponding to the specified measurement operation, and providing a completion signal upon completion of the processor operations and thereafter entering a standby state following a first delay interval, the apparatus further comprising a clock signal generator for providing a clock signal to the digital processor means, a bistable circuit responsive to the command signal for providing a set state signal at an output thereof and responsive to the completion signal for providing a reset state signal at the output, and a delay circuit for delaying the reset state signal at the output of the bistable circuit by a second delay interval equal to or greater than the first delay interval and providing the delayed reset state signal to the clock signal generator, the clock signal generator being deactivated in response to the delayed reset state signal whereby the digital processor means is permitted to enter the standby state before the clock signal generator circuit is deactivated.

5. An apparatus for measuring a physical quantity and providing corresponding measurement data comprising:

(a) transducer/converter means for converting a physical quantity being measured to a corresponding frequency signal having a frequency which is related to the physical quantity;

(b) counter means responsive to the frequency signal for providing a digital quantity related to the frequency of the frequency signal;

(c) digital processor means for performing predetermined processing operations on the digital quantity and providing measurement data corresponding to the physical quantity being measured; and

(d) a transceiver unit including an electrical-to-optical transducer for converting the measurement data into optical information for transmission to a central processor and an optical-to-electrical transducer for receiving optical information from the central processor and for converting the received optical information to electrical signals, wherein the transceiver unit includes delay means between the optical-to-electrical transducer and the electrical-to-optical transducer for delaying information received by the optical-to-electrical transducer by a delay interval particular to the apparatus and providing the delayed information directly to the electrical-to-optical transducer for retransmission back to the central processor whereby a failure in the transceiver unit of the apparatus or of the transmission path connected thereto is diagnosable by the central processor from the absence of retransmitted information from the apparatus following the particular delay interval.

6. An apparatus for measuring a physical quantity and providing corresponding measurement data comprising:

(a) transducer/converter means for converting a physical quantity being measured to a corresponding frequency signal having a frequency which is related to the physical quantity;

(b) counter means responsive to the frequency signal for providing a digital quantity related to the frequency of the frequency signal;

(c) digital processor means for performing predetermined processing operations on the digital quantity and providing measurement data corresponding to the physical quantity being measured; and

(d) a transceiver unit including an electrical-to-optical transducer for converting the measurement data into optical information for transmission to a central processor and an optical-to-electrical transducer for receiving optical information from the central processor and for converting the received optical information to electrical signals, wherein the electrical-to-optical transducer means include a light-emitting element, driver means responsive to data from the digital processor means for providing intermittent current to the light-emitting element, and current control means for sensing and integrating the current flow to the light-emitting element and for interrupting the current from the driver means in response to the integrated current flow exceeding a predetermined level thereby preventing the light-emitting element from being activated for longer than a specified interval.

7. An apparatus for measuring a physical quantity and providing corresponding measurement data comprising:

(a) transducer/converter means for converting a physical quantity being measured to a corresponding frequency signal having a frequency which is related to the physical quantity;

(b) counter means responsive to the frequency signal for providing a digital quantity related to the frequency of the frequency signal;

(c) digital processor means for performing predetermined processing operations on the digital quantity and providing measurement data corresponding to the physical quantity being measured; and

(d) a transceiver unit including an electrical-to-optical transducer for converting the measurement data into optical information for transmission to a central processor and an optical-to-electrical transducer for receiving optical information from the central processor and for converting the received optical information to electrical signals, wherein the apparatus is optically coupled to the central processor through divider/coupler means for optically coupling the central processor to a plurality of measurement apparatus, the central processor including two transceiver units each coupled to the divider/coupler means through a respective optical transmission link, the transceiver units of the central processor being alternately selected to transmit command information to each of the plurality of measurement apparatus, each measurement apparatus being adapted to transmit return information to the central processor in response to receiving the command information, the central processor being adapted to detect and diagnose failures in its transceiver units, the optical transmission links coupled thereto and the divider/coupler means by analyzing the patterns of reception and non-reception of return data by the transceiver units when first one and then the other transceiver unit is selected to transmit command information.