CA1218871A - Measuring device - Google Patents
Measuring deviceInfo
- Publication number
- CA1218871A CA1218871A CA000467163A CA467163A CA1218871A CA 1218871 A CA1218871 A CA 1218871A CA 000467163 A CA000467163 A CA 000467163A CA 467163 A CA467163 A CA 467163A CA 1218871 A CA1218871 A CA 1218871A
- Authority
- CA
- Canada
- Prior art keywords
- voltage
- measuring means
- measuring
- comparison
- source
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D21/00—Measuring or testing not otherwise provided for
- G01D21/02—Measuring two or more variables by means not covered by a single other subclass
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Testing Or Calibration Of Command Recording Devices (AREA)
- Measurement Of Resistance Or Impedance (AREA)
Abstract
Measuring Device Abstract of the Disclosure A measuring device for measuring physical quantities such as liquid level and temperature from changes in a resistor contained in a sensor of various types such as a liquid level sensor and a temperature sensor. A physical quantity is measured by a plurality of measuring menas and is displayed as a plurality of data obtained either directly or by computational operations in combination with information related to other physical quantities but occurrence of differences in the results obtained from different measuring means is prevented.
Description
12~871 This invention relates to a device for measuring a physical quantity and particularly to a measuring device which measures a single physical quantity by a plurality Of measuring means and utilizes the results as information.
The present invention will be illustrated by way of the accompanying drawings, in which:-Fig. 1 is a block diagram showing an embodiment of the measuring device according to the present invention;
Fig. 2 is a block diagram of the comparison circuit;
Fig. 3 is a time chart which shows the output voltage from the microcomputer;
Fig. 4 is a diagram for explaining the comparison method by the comparator; and Fig. 5 is a block diagram showing a prior art device.
Temperature sensors, gas density sensors and liquid level sensors measure physical quantities from the change in the resistance of a resistor which varies accord-in to its external environment. Measured resistance of such a resistor is not used directly but is taken out after it is electrically converted into voltage, current or ire-quench by a measuring means at a later stage within the device and the information in the form of a physical van-able into which it has been converted is subjected to van-ions controls and then displayed by a display means.
There is no problem if the structure of the device is such that only one physical quantity is measured as in-~Z18871 formation by one measuring means and then displayed. With the application of modern electronics, for example, to the display panels of automobiles, however, there are now devil cues capable of displaying more than one type of information on the basis of only one physical variable but by carrying out various computational operations thereon. There is desk cried in So Patent No. 4,061,023, for example, a device which measures the momentary amount of fuel consumed by a running vehicle and obtains not only the total amount of the fuel consumed by integrating it but at the same time also the momentary rate of fuel consumption by carrying out a computational operation. In order to obtain two or more types of information from one measured physical quantity as in this example, the device may be so designed that this physical quantity is transmitted to a plurality of - lo -12~8~71 measuring means where different operations are performed, displays being made thereafter by display means connected to the measuring means. For example, the voltage corresponding to the amount of the fuel remaining in a running vehicle may be transmitted to both first and second measuring means where the first measuring means is only for measuring the remaining amount of the fuel while the second measuring means also receives information such as running time and traveled distance and measures not only the remaining amount of the fuel but also the total amount of the fuel consumed and the rate of fuel consumption per unit time, the display being made by display means connected to them. sty this design, however, measurement errors may be caused by the power sources of the individual measuring means.
Referring to FIG. 5, a rheostat Rx as a sensor is connected in series with a pulp resistor Row to a power source 2 in a first measuring means 1 which also includes a comparison circuit 3 for obtaining information by converting the physical quantity measured by sensor Rx into an electrical quantity and a control circuit 5 for outputting this information at a display means 4 at a later stage. The comparison and control circuits 3 and 5 are powered by the source I, and the comparison circuit 3 measures the physical quantity by comparing the voltage between the terminals of the rheostat Rx and the comparison voltage from the source voltage ODD. The second measuring means 7 is for measuring the physical quantity by the same sensor and making an output at another display means 6 and is also provided with a power source 8, a comparison circuit 9 and a control circuit 10. Sensors 11 are connected to this control circuit 10 and output electrical signals in accordance with the conditions of other physical quantities. The comparison circuit 9 and the control circuit 10 are powered by the voltage ODD of the source 8.
In the case of a prior art device thus constructed, voltage RXVDD/(Rx + Row appears at the input ends of the 121887~
comparison circuits 3 and 9. If resistance Row is now assumed to be known, RX/(Rx + Row becomes a fixed curve.
Thus, resistance Rx can be obtained by both measuring means 1 and 7 by comparing RxVDD/(~x + Row and the comparison voltage from source voltage ED in comparison circuit 3 and y p no RXVDD/(Rx + Row and the comparison voltage from source voltage ED in comparison circuit 9.
Source voltages, however, fluctuate mostly within 10%.
This presents no problem to the comparison circuit 3 of the first measuring means 1 because this applies ODD to the rheostat Rx so that, if ODD fluctuates, what is being compared also fluctuates at the same ratio. In the case of the comparison circuit 9 of the second measuring means 7, the output will be the same as that from the comparison circuit 3 if source voltage ODD is the same as or maintained at a fixed ratio with respect to ODD because what is being compared will then again fluctuate at the same ratio. Since source voltages may fluctuate by up to 10%, however, a maximum measurement error of about 20% will result in the comparison circuit 9 if the fluctuation in source voltage ODD is I 0% and that in source voltage ODD
is -10%. Although this problem of measurement error can be resolved by preliminarily adjusting the source voltage ODD
of source 8 to the source voltage ODD of source 2, it is extremely cumbersome to make such an adjustment before each measurement especially if there is a large number of measuring means. Moreover, such adjustments cannot be effective for sudden fluctuations in a source voltage. In the past, therefore, different measured values were often obtained due to the fluctuations of source voltages if two or more measuring means were used for one physical quantity.
Summary of the Invention It is an object of this invention to provide a measuring device which, having a plurality of measuring means for one physical quantity, is capable of yielding the lZ~8871 same measured value by each of these measuring means.
According to the present invention there is provided a measuring device adapted to supply a detection voltage corresponding to a condition of a physical quantity to a plurality of measuring means and to make displays related to said physical quantity at display means connected to said measuring means, said measuring device being char-acterized in that each of said measuring means includes a comparison circuit for measuring said physical quantity by entering said detection voltage and comparing said detection voltage with a comparison voltage and that said comparison voltage is supplied from a common source which generates said detection voltage. Suitably said comparison voltage is generated by a ladder-type resistor circuit for analog-digital conversion.
Referring now to Fig. 1, a first measuring means 21 is provided with a power source 22, a comparison circuit 23 and a control circuit 24, and there is a display means 25 connected at a later stage. A rheostat R as a sensor in series with a pull-up resistor R is connected to the source 22, and the comparison circuit 23 and the control circuit 24 are powered by the source voltage ODD of -the source 22. A
second measuring means 26 is similarly provided with a power source 27 r a comparison circuit 28 and a control circuit 29.
Sensors 30 which output electrical signals in accordance with the conditions of other physical quantities are con-netted to the control circuit 29 and a display means 31 is connected at a later stage. The comparison circuit 28, how-ever, is powered by the source 22 of the first measuring means 21 while the control circuit 29 is powered by the g DUD source 27.
Fig. 2 is a block diagram which shows an embody-mint of comparison circuits 23 and 28 wherein No. 32 is a Jo ~218871 comparator and No. 33 is a microcomputer. Since resistors Al, R2 and R3 are connected respectively to three output terminals A, B and C of the microcomputer 33, while parallel resistors R4, R5 and R6 are connected respectively between them and the ground so as to form a ladder-type resistor network for - pa -analog-digital conversion. The values of resistance of these resistors R1 - R6 are such that R1 = R2 = R3 = R6 =
2R4 = 2R5, and the junction point between resistors R1 and R4 is connected to the non-inversion input terminal D of the comparator 32 while the inversion input terminal E of the comparator 32 is connected to the junction point of the pulp resistor Row and the rheostat Rx. Its output terminal F is connected to the control circuit 24 or 29 through the microcomputer 33.
In operation, the source voltage ED of source 22 is applied to the rheostat Rx and this generates a detection voltage RXVDD/(~X + Row which becomes an input to the comparator 32. In the meantime, the voltage output at the output terminals A, B and C of the microcomputer 33 is either "H" (high) or "L" (low, or ODD = O) as shown in FIG.
3 so that a total of 8 different comparison voltages ranging in value between O and 7VDD/8 can be output by combining the three output voltages at terminals A, B and C. The comparison voltage in this range is repeatedly output either periodically or periodically and enters the comparator 32.
The comparator 32 then compares the voltage between the terminals of the rheostat Rx with the output voltage from the output terminals A, B and C of the microcomputer 33 and, when their magnitude relationship changes, an output inverted from the previous output is transmitted to the microcomputer 33. The microcomputer 33 then performs computational operations on the value of variable resistance Rx in accordance with the signals output from the terminals A, I and C and makes an output to the control circuit 24 or 29.
Since, as explained above, the same source voltage ODD
is applied to the comparison circuits 23 and 28 of the first and second measuring means 21 and 26, the same comparison can be effected by the comparator 32 regarding the rheostat Rx and the same measured value can be obtained from the different measuring means. FIG. 4 shows the comparison with WOW
the voltage RXVDD/(Rx + Row between the terminals of the rheostat Rx when the source voltage ODD is divided into 8 steps. While the source voltage which should be 7VDD/8 due to fluctuation would become 7V'DD/8 if different power sources were used for comparison circuits of different measuring means as in the case of prior art devices and this would result in different measured values from different measurement sections, such inconvenience is obviated by a device of the present invention described above.
Although the control circuits 24 and 29 are shown to be powered by different sources, there is no problem because source voltages do not relate directly to the measured values.
As shown above, when two or more measuring means are used to measure one variable resistance Rx, the present invention teaches to supply source voltage from the same source to the comparison circuits for comparing the individual voltages so that the same measured value can be obtained for Rx, independently of the voltage fluctuations at the individual measuring means. This contributes to increase the accuracy of measurement.
Although only one embodiment has been shown and described herein, it should be understood that many changes and modifications may be made therein without departing from the scope of the appended claims. For example, there may be more than two measuring means. Likewise, the number of output terminals A, B and C of the microcomputer 33 is not limited to 3. If this number is increased, resolution of the measured value can be increased and accuracy of measurement is improved.
In summary, the present invention provides a measuring device which, with plurality of measurement sections connected for one physical quantity, allows to obtain the same measured value at each of the measuring means.
The present invention will be illustrated by way of the accompanying drawings, in which:-Fig. 1 is a block diagram showing an embodiment of the measuring device according to the present invention;
Fig. 2 is a block diagram of the comparison circuit;
Fig. 3 is a time chart which shows the output voltage from the microcomputer;
Fig. 4 is a diagram for explaining the comparison method by the comparator; and Fig. 5 is a block diagram showing a prior art device.
Temperature sensors, gas density sensors and liquid level sensors measure physical quantities from the change in the resistance of a resistor which varies accord-in to its external environment. Measured resistance of such a resistor is not used directly but is taken out after it is electrically converted into voltage, current or ire-quench by a measuring means at a later stage within the device and the information in the form of a physical van-able into which it has been converted is subjected to van-ions controls and then displayed by a display means.
There is no problem if the structure of the device is such that only one physical quantity is measured as in-~Z18871 formation by one measuring means and then displayed. With the application of modern electronics, for example, to the display panels of automobiles, however, there are now devil cues capable of displaying more than one type of information on the basis of only one physical variable but by carrying out various computational operations thereon. There is desk cried in So Patent No. 4,061,023, for example, a device which measures the momentary amount of fuel consumed by a running vehicle and obtains not only the total amount of the fuel consumed by integrating it but at the same time also the momentary rate of fuel consumption by carrying out a computational operation. In order to obtain two or more types of information from one measured physical quantity as in this example, the device may be so designed that this physical quantity is transmitted to a plurality of - lo -12~8~71 measuring means where different operations are performed, displays being made thereafter by display means connected to the measuring means. For example, the voltage corresponding to the amount of the fuel remaining in a running vehicle may be transmitted to both first and second measuring means where the first measuring means is only for measuring the remaining amount of the fuel while the second measuring means also receives information such as running time and traveled distance and measures not only the remaining amount of the fuel but also the total amount of the fuel consumed and the rate of fuel consumption per unit time, the display being made by display means connected to them. sty this design, however, measurement errors may be caused by the power sources of the individual measuring means.
Referring to FIG. 5, a rheostat Rx as a sensor is connected in series with a pulp resistor Row to a power source 2 in a first measuring means 1 which also includes a comparison circuit 3 for obtaining information by converting the physical quantity measured by sensor Rx into an electrical quantity and a control circuit 5 for outputting this information at a display means 4 at a later stage. The comparison and control circuits 3 and 5 are powered by the source I, and the comparison circuit 3 measures the physical quantity by comparing the voltage between the terminals of the rheostat Rx and the comparison voltage from the source voltage ODD. The second measuring means 7 is for measuring the physical quantity by the same sensor and making an output at another display means 6 and is also provided with a power source 8, a comparison circuit 9 and a control circuit 10. Sensors 11 are connected to this control circuit 10 and output electrical signals in accordance with the conditions of other physical quantities. The comparison circuit 9 and the control circuit 10 are powered by the voltage ODD of the source 8.
In the case of a prior art device thus constructed, voltage RXVDD/(Rx + Row appears at the input ends of the 121887~
comparison circuits 3 and 9. If resistance Row is now assumed to be known, RX/(Rx + Row becomes a fixed curve.
Thus, resistance Rx can be obtained by both measuring means 1 and 7 by comparing RxVDD/(~x + Row and the comparison voltage from source voltage ED in comparison circuit 3 and y p no RXVDD/(Rx + Row and the comparison voltage from source voltage ED in comparison circuit 9.
Source voltages, however, fluctuate mostly within 10%.
This presents no problem to the comparison circuit 3 of the first measuring means 1 because this applies ODD to the rheostat Rx so that, if ODD fluctuates, what is being compared also fluctuates at the same ratio. In the case of the comparison circuit 9 of the second measuring means 7, the output will be the same as that from the comparison circuit 3 if source voltage ODD is the same as or maintained at a fixed ratio with respect to ODD because what is being compared will then again fluctuate at the same ratio. Since source voltages may fluctuate by up to 10%, however, a maximum measurement error of about 20% will result in the comparison circuit 9 if the fluctuation in source voltage ODD is I 0% and that in source voltage ODD
is -10%. Although this problem of measurement error can be resolved by preliminarily adjusting the source voltage ODD
of source 8 to the source voltage ODD of source 2, it is extremely cumbersome to make such an adjustment before each measurement especially if there is a large number of measuring means. Moreover, such adjustments cannot be effective for sudden fluctuations in a source voltage. In the past, therefore, different measured values were often obtained due to the fluctuations of source voltages if two or more measuring means were used for one physical quantity.
Summary of the Invention It is an object of this invention to provide a measuring device which, having a plurality of measuring means for one physical quantity, is capable of yielding the lZ~8871 same measured value by each of these measuring means.
According to the present invention there is provided a measuring device adapted to supply a detection voltage corresponding to a condition of a physical quantity to a plurality of measuring means and to make displays related to said physical quantity at display means connected to said measuring means, said measuring device being char-acterized in that each of said measuring means includes a comparison circuit for measuring said physical quantity by entering said detection voltage and comparing said detection voltage with a comparison voltage and that said comparison voltage is supplied from a common source which generates said detection voltage. Suitably said comparison voltage is generated by a ladder-type resistor circuit for analog-digital conversion.
Referring now to Fig. 1, a first measuring means 21 is provided with a power source 22, a comparison circuit 23 and a control circuit 24, and there is a display means 25 connected at a later stage. A rheostat R as a sensor in series with a pull-up resistor R is connected to the source 22, and the comparison circuit 23 and the control circuit 24 are powered by the source voltage ODD of -the source 22. A
second measuring means 26 is similarly provided with a power source 27 r a comparison circuit 28 and a control circuit 29.
Sensors 30 which output electrical signals in accordance with the conditions of other physical quantities are con-netted to the control circuit 29 and a display means 31 is connected at a later stage. The comparison circuit 28, how-ever, is powered by the source 22 of the first measuring means 21 while the control circuit 29 is powered by the g DUD source 27.
Fig. 2 is a block diagram which shows an embody-mint of comparison circuits 23 and 28 wherein No. 32 is a Jo ~218871 comparator and No. 33 is a microcomputer. Since resistors Al, R2 and R3 are connected respectively to three output terminals A, B and C of the microcomputer 33, while parallel resistors R4, R5 and R6 are connected respectively between them and the ground so as to form a ladder-type resistor network for - pa -analog-digital conversion. The values of resistance of these resistors R1 - R6 are such that R1 = R2 = R3 = R6 =
2R4 = 2R5, and the junction point between resistors R1 and R4 is connected to the non-inversion input terminal D of the comparator 32 while the inversion input terminal E of the comparator 32 is connected to the junction point of the pulp resistor Row and the rheostat Rx. Its output terminal F is connected to the control circuit 24 or 29 through the microcomputer 33.
In operation, the source voltage ED of source 22 is applied to the rheostat Rx and this generates a detection voltage RXVDD/(~X + Row which becomes an input to the comparator 32. In the meantime, the voltage output at the output terminals A, B and C of the microcomputer 33 is either "H" (high) or "L" (low, or ODD = O) as shown in FIG.
3 so that a total of 8 different comparison voltages ranging in value between O and 7VDD/8 can be output by combining the three output voltages at terminals A, B and C. The comparison voltage in this range is repeatedly output either periodically or periodically and enters the comparator 32.
The comparator 32 then compares the voltage between the terminals of the rheostat Rx with the output voltage from the output terminals A, B and C of the microcomputer 33 and, when their magnitude relationship changes, an output inverted from the previous output is transmitted to the microcomputer 33. The microcomputer 33 then performs computational operations on the value of variable resistance Rx in accordance with the signals output from the terminals A, I and C and makes an output to the control circuit 24 or 29.
Since, as explained above, the same source voltage ODD
is applied to the comparison circuits 23 and 28 of the first and second measuring means 21 and 26, the same comparison can be effected by the comparator 32 regarding the rheostat Rx and the same measured value can be obtained from the different measuring means. FIG. 4 shows the comparison with WOW
the voltage RXVDD/(Rx + Row between the terminals of the rheostat Rx when the source voltage ODD is divided into 8 steps. While the source voltage which should be 7VDD/8 due to fluctuation would become 7V'DD/8 if different power sources were used for comparison circuits of different measuring means as in the case of prior art devices and this would result in different measured values from different measurement sections, such inconvenience is obviated by a device of the present invention described above.
Although the control circuits 24 and 29 are shown to be powered by different sources, there is no problem because source voltages do not relate directly to the measured values.
As shown above, when two or more measuring means are used to measure one variable resistance Rx, the present invention teaches to supply source voltage from the same source to the comparison circuits for comparing the individual voltages so that the same measured value can be obtained for Rx, independently of the voltage fluctuations at the individual measuring means. This contributes to increase the accuracy of measurement.
Although only one embodiment has been shown and described herein, it should be understood that many changes and modifications may be made therein without departing from the scope of the appended claims. For example, there may be more than two measuring means. Likewise, the number of output terminals A, B and C of the microcomputer 33 is not limited to 3. If this number is increased, resolution of the measured value can be increased and accuracy of measurement is improved.
In summary, the present invention provides a measuring device which, with plurality of measurement sections connected for one physical quantity, allows to obtain the same measured value at each of the measuring means.
Claims (2)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A measuring device adapted to supply a detection voltage corresponding to a condition of a physical quantity to a plurality of measuring means and to make displays related to said physical quantity at display means connected to said measuring means, said measuring device being characterized in that each of said measuring means includes a comparison circuit for measuring said physical quantity by entering said detection voltage and comparing said detection voltage with a comparison voltage and that said comparison voltage is supplied from a common source which generates said detection voltage.
2. The measuring device of claim 1 wherein said comparison voltage is generated by a ladder-type resistor circuit for analog-digital conversion.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59-110344 | 1984-05-29 | ||
| JP11034484A JPS60252220A (en) | 1984-05-29 | 1984-05-29 | Measuring instrument |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1218871A true CA1218871A (en) | 1987-03-10 |
Family
ID=14533373
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000467163A Expired CA1218871A (en) | 1984-05-29 | 1984-11-06 | Measuring device |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS60252220A (en) |
| CA (1) | CA1218871A (en) |
-
1984
- 1984-05-29 JP JP11034484A patent/JPS60252220A/en active Pending
- 1984-11-06 CA CA000467163A patent/CA1218871A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60252220A (en) | 1985-12-12 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |