CN107707255B - Conversion module arranged between detector and analog-to-digital converter - Google Patents
Conversion module arranged between detector and analog-to-digital converter Download PDFInfo
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- CN107707255B CN107707255B CN201610643104.3A CN201610643104A CN107707255B CN 107707255 B CN107707255 B CN 107707255B CN 201610643104 A CN201610643104 A CN 201610643104A CN 107707255 B CN107707255 B CN 107707255B
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
- H03M1/00—Analogue/digital conversion; Digital/analogue conversion
- H03M1/12—Analogue/digital converters
Abstract
The invention provides a conversion module arranged between a detector and an analog-to-digital converter, comprising: the voltage dividing circuit is electrically connected with the detector and is used for receiving an input signal from the detector and outputting an adjusted detection signal to the analog-to-digital converter after adjusting the voltage of the input signal.
Description
Technical Field
The present invention relates to security technology, and more particularly, to technology for converting a detection signal of a detector into an analog converter.
Background
Security systems are currently used in many applications, such as airports, buildings, communities, schools, and the like. The security system generally comprises a front-end data acquisition part for acquiring field data and a data processing part for receiving and processing the field data. Most security systems also include a portion that alarms when an abnormal situation is found and/or an emergency handling portion that handles an emergency situation.
Taking a smoke detection system in a security system as an example, it generally includes a smoke concentration detection module, a power supply, and a back-end processing portion. The power supply provides power for each module, and the smoke concentration detection module collects on-site smoke concentration data and transmits the collected data to the rear-end processing part. The back-end processing section performs analog-to-digital conversion or the like on the acquired data to determine whether or not warning and/or other coping processes are required based on the data.
The back-end processing portion includes a conversion portion for converting the data collected by the smoke concentration detection module into a signal, such as a voltage signal, that can be subsequently and efficiently processed by the back-end processing portion. As is known, the variety of commercially available detectors (or probes) is so large that the back-end processing unit is expensive to install different switching units when different probes are connected.
There are also solutions with one conversion part for two or three types. In this solution, the analog-to-digital converter provided at the back-end processing section must have a considerable accuracy to cope with the different inputs.
Disclosure of Invention
In view of this, the present invention provides a conversion module disposed between a detector and an analog-to-digital converter to solve at least one of the above-mentioned problems. The conversion module arranged between the detector and the analog-to-digital converter comprises a voltage division circuit electrically connected with the detector and is used for receiving an input signal from the detector and outputting an adjusted detection signal to the analog-to-digital converter after adjusting the voltage of the input signal.
Optionally, the voltage dividing circuit of the conversion module arranged between the detector and the analog-to-digital converter according to an example of the invention further comprises a switch for, when turned off, causing only a basic voltage dividing resistance of the voltage dividing circuit to be connected into the circuit between the detector and the analog-to-digital converter, and when turned on, causing the voltage dividing circuit to be connected into the circuit between the detector and the analog-to-digital converter as a whole.
According to the conversion module of the present example, the voltage dividing circuit may include an effect transistor having a field as a switch, a first voltage dividing resistor disposed between a source and a gate of the field effect transistor, a second voltage dividing resistor disposed between a gate and a drain of the field effect transistor, and a third voltage dividing resistor disposed between the source and the drain of the field effect transistor as a basic voltage dividing resistor.
According to the conversion module provided between the detector and the analog-to-digital converter of the present invention, optionally, the gate of the field effect transistor is provided as an enable terminal.
The conversion module according to an example of the invention, which is arranged between the detector and the analog-to-digital converter, optionally further comprises a resistive circuit, which is arranged between the voltage dividing circuit and the analog-to-digital converter.
The conversion module according to an example of the invention, which is arranged between the detector and the analog-to-digital converter, optionally further comprises a follower circuit, which is arranged between the output of the voltage divider circuit and the input of the resistor circuit.
According to one aspect of the present invention there is also provided a detection method for a detection system comprising a detector and an analogue to digital converter, the method comprising: before analog-to-digital conversion is carried out on the detection signal from the detector, the voltage of the detection signal is adjusted through a voltage dividing circuit; converting the adjusted voltage signal into a digital signal; and processing based on the digital signal to determine whether the detected site is abnormal.
According to an aspect of the present invention, there is further provided a detection system, which includes a detection portion, a conversion module electrically connected to the detection portion, and a back-end processing portion, wherein the conversion module is any one of the conversion modules described above.
According to still another aspect of the present invention, there is further provided a smoke detection system, which includes a smoke detection portion, a conversion module electrically connected to the smoke detection portion, and a back-end processing portion, wherein the conversion module is any one of the conversion modules described above.
According to a further aspect of the invention, there is also provided a detection system comprising a detector and an analog-to-digital converter, and performing the detection method for a detection system according to the named examples of the invention.
Drawings
Fig. 1 is a schematic block diagram of a smoke detection system according to an example of the invention.
Fig. 2 is a schematic block diagram of a conversion module according to an example of the invention.
Fig. 3 is a schematic circuit diagram of a conversion module according to a specific example of the present invention.
Fig. 4 is a flow chart of a detection method for a detection system according to an example of the invention.
Detailed Description
Illustrative examples of the invention will now be described with reference to the drawings, wherein like reference numerals refer to like elements throughout. The examples described below, which are intended as examples and not as limitations, are intended to provide a thorough understanding of the present invention to those skilled in the art. The illustrations of elements, components, modules, devices, and apparatus bodies in the figures are not drawn to scale, and only schematic representations of the relative relationships between the elements, components, modules, devices, and apparatus bodies are provided.
Fig. 1 is a schematic block diagram of a smoke detection system according to an example of the invention. As shown in fig. 1, the detecting portion 20 is electrically connected to the back-end processing portion 24 through the converting module 22. The back-end processing section 24 includes an analog-to-digital converter (AD converter) 241 and a controller 242. The detection unit 20 detects smoke in the field 10 and transmits a detection signal to the conversion module 22. The conversion module 22 converts the received detection signal into an appropriate voltage signal, which is sent to the AD converter 241, which digitizes the voltage signal. The digitized voltage signal is transmitted to the controller 242 by the AD converter 241. The controller 242 determines from this signal whether an anomaly has occurred in the smoke content of the field 10. In some examples, the controller 242 may also control its associated components to perform corresponding processing in the event of an anomaly, such as by alerting a warning device, etc.
Fig. 2 is a schematic block diagram of a conversion module 22 according to an example of the invention. As shown in fig. 2, the conversion module 22 includes a voltage divider circuit 222. Before further describing the present invention with reference to fig. 2, a brief description of the detection portion 20 (see fig. 1) will be provided. The detection unit 20 includes a probe and a termination resistor. The different types of probes correspond to different terminal resistances, and the resistance values of the terminal resistances required by the different types of probes can be referred to the specification (Datasheet) of each probe. According to an example of the present invention, a plurality of termination resistors may be connected to the input of the voltage divider 222 to correspond to different types of probes. For example, after the type a probe is selected, the type a probe is electrically connected to a termination resistor corresponding to the type a probe from among a plurality of termination resistors.
Referring to fig. 1 and 2, the detection unit 20 detects smoke in the field, and transmits a smoke detection signal to the voltage dividing circuit 222 via one of the terminating resistors electrically connected to the probe 20, and the voltage dividing circuit 222 converts the detection signal into an appropriate voltage signal and outputs the voltage signal.
According to an example of the invention, the voltage divider circuit of the conversion module further comprises a switch (not shown in the figure). When the switch is opened, only a substantial voltage dividing resistor in the voltage dividing circuit is connected to the circuit between the detector and the analog-to-digital converter. When the switch is turned on, the voltage divider circuit is connected to the circuit between the detector and the analog-to-digital converter. In other words, according to this example, there is a basic voltage dividing resistor in the voltage dividing circuit for adjusting the voltage of the electrical signal from the detector to the AD converter, whether or not the switch is on, the switch being turned off and on only differing in the number and magnitude of the voltage dividing resistor in the circuit between the detector and the AD converter to which the voltage dividing circuit is connected.
In some examples, the detection signal is converted to an appropriate voltage signal via the voltage divider circuit 222 and then directly input to the analog-to-digital converter 241 (see fig. 1).
In still other examples, the conversion module 22 shown in fig. 2 further includes a resistor circuit disposed after the voltage divider circuit 222 for electrically connecting with the AD converter 241 (see fig. 1). One end of the resistor circuit receives an input from the voltage divider 222, and the other end is electrically connected to the AD converter 241.
According to further examples of the invention, the conversion module 22 further comprises a follower circuit. According to an example of the present invention, a follower circuit is provided at the output terminal of the voltage dividing circuit 222, so that the output from the voltage dividing circuit 222 is transmitted to the AD converter 241 (see fig. 1) after passing through the follower circuit.
According to a specific example of the present invention, the conversion module includes a voltage dividing circuit, a follower circuit, and a resistor circuit. The conversion module 22 shown in fig. 2 includes a voltage dividing circuit 222, a follower circuit 225, and a resistor circuit 226. The follower circuit 225 is disposed between the voltage divider 222 and the resistor circuit 226, and the resistor circuit 226 is disposed behind the follower circuit 225 and is electrically connected to an analog-to-digital converter (AD converter) 241 (see fig. 1). In this example, the voltage divider circuit 222 includes a switch 223, a basic voltage divider resistor 2220, and two other resistors labeled 2221 and 2222, where the resistors 2221 and 2222 are electrically connected to the switch 223. When the switch 223 is turned on, the resistors 2221 and 2222 are connected in parallel with the basic voltage dividing resistor 2220, and together achieve a voltage dividing function. When switch 223 is open, only the basic voltage divider resistor 2220 operates in the circuit. Although only three resistors are illustrated in the drawing, the number of actual resistors is not limited thereto. In addition, the arrangement of the switch is not limited to one.
Referring to fig. 1, in converting an analog signal into a digital signal, an operation curve of the AD converter 241 is not linear. The larger the input impedance of the probe 20 is, the larger the error is when the AD converter 241 converts the detection signal from the detection unit.
Referring to fig. 2 and 1, with the conversion module 22 of the present embodiment, the detection signal of the detection portion 20 first passes through the voltage dividing circuit 222, so that the voltage value of the voltage signal to be transmitted to the AD converter 241 is reduced, which enables the AD converter 241 to obtain a more accurate conversion result with a limited conversion accuracy, so that the controller 242 can determine the field signal more accurately.
Furthermore, as with conventional detection systems, the voltage signals to be detected are allowed to have a certain tolerance, for example + -30%. Without the provision of a voltage divider circuit, the range of voltage values of the voltage signal within the tolerance allowable range (+30% and-30%) becomes narrower as the probe impedance increases, as will be described below in connection with the specific example of fig. 3.
According to an illustrative example of the present invention, the voltage divider circuit of the conversion module 22 may be implemented by a field effect transistor (as a switch) and a resistor. Thus, the voltage divider circuit is illustratively implemented as follows: a first voltage dividing resistor is provided between the source and the gate of the field effect transistor, a second voltage dividing resistor is provided between the gate and the drain of the field effect transistor, and a third voltage dividing resistor (as a basic voltage dividing resistor) is provided between the source and the drain of the field effect transistor. Wherein, the source electrode of the field effect transistor receives the detection signal from the detection part. The gate of the field effect transistor may be used as the enable terminal of the field effect transistor, i.e. as a switch of the voltage divider circuit.
Fig. 3 illustrates a schematic circuit diagram of a conversion module according to a specific example of the invention. In the example shown in fig. 3, the field effect transistor is a MOSFET. In this example, the MOSFET constitutes the voltage dividing circuit 322 together with a first voltage dividing resistor provided between its source and gate, a second voltage dividing resistor provided between the gate and drain, and a third voltage dividing resistor provided between the source and drain. When the MOSFET is fully turned on, the voltage dividing resistor Rz constituted by the first voltage dividing resistor, the second voltage dividing resistor, and the third voltage dividing resistor is mainly used as the voltage dividing resistor Rz when the MOSFET is turned off between the source and the gate of the MOSFET. The MOSFET may be made to be fully on or off by operating the gate, hereinafter also referred to as the enable terminal, where the MOSFET is fully on, whereas the MOSFET is off between the source and gate.
As shown in fig. 3, the detection unit 30 transmits a detection signal to the voltage dividing circuit 322, and the voltage of the detection signal is adjusted by the voltage dividing circuit 322. The adjusted detection signal is then passed to follower circuit 325. The follower circuit 325 outputs the detection signal to the resistor circuit 326 again, and then, via the resistor circuit 326, the adjustment signal is transmitted as an output signal of the conversion module 32 to, for example, an AD converter 241 in fig. 1.
The detection unit 30 includes a probe and a termination resistor electrically connected to the probe and transmitting a detection signal of the probe to the voltage dividing circuit 322. The portion 3a of fig. 3 illustrates the probe 50 and the terminating resistor 52, in other words, the portion 3a illustrates a specific example of the detecting portion 30, and a line segment for connecting the detecting portion 30 and the portion 3a only illustrates this, not to say that there is an electrical connection between the detecting portion 20 and the portion denoted by 3 a. The probe 50 is illustrated as having an equivalent resistance Rt, and the wires connecting the probe 50 to the corresponding termination resistances in the termination resistance portion 52 are equivalent to the resistance Rw. The number of termination resistors is illustrated in section 3a, which is not to say that the probe 50 must be connected to a plurality of termination resistors, but is merely illustrative of the fact that the termination resistors are optional here, and as mentioned above, may be selected depending on the type of probe 50.
In the schematic diagram shown in fig. 3, the first voltage dividing resistor R192 is 4.75K, the second voltage dividing resistor R109 is 10.0K, the third voltage dividing resistor R171 is 8.20K, the first resistor R17 in the resistor circuit 326 is 3.30K, the second resistor R136 is 5.6K, and other values of the electronic devices described herein can be seen in the drawings.
Table 1 shows the conversion module according to fig. 3, in which the MOSFET as a switch is in the off state, i.e. the value of some parameter is not switched on between the source and the gate of the MOSFET. Where Rt is the impedance of the probe 50, rz is the impedance of the voltage divider circuit, vz is the voltage of the voltage divider circuit, vi/o is the voltage of the resistor circuit 326 actually tested, and Nv is the theoretical voltage of the signal that the calculated conversion module is to output to the AD converter 241 (see fig. 1).
TABLE 1
Table 2 is the values of some parameters of the converter according to fig. 3 in case the MOSFET as switch is on, i.e. between the source and gate of the MOSFET. Where Rt is the impedance of the probe, rz is the impedance of the voltage divider circuit, vz is the voltage of the voltage divider circuit, vi/o is the voltage of the resistor circuit 326 actually tested, and Nv is the theoretical voltage that the calculated conversion module is to output to the AD converter 241.
TABLE 2
As can be seen from comparing table 1 with table 2, when the probe impedance becomes large without enabling, that is, without voltage division by the voltage division circuit, the range of the voltage value of the voltage signal becomes narrower within the tolerance allowable range (+30% and-30%). For example, for a probe having an impedance of 12.1 kiloohms, the range of theoretical voltage values calculated for the conversion module to output to the AD converter 241 (see fig. 1) is a minimum 2.32088735 volts, a maximum 2.6418448, and for a probe having an impedance of 22 kiloohms, the range of theoretical voltage values calculated for the conversion module to output to the AD converter 241 (see fig. 1) is a minimum 2.63281738 volts, a maximum 2.84699607; however, in the case where the first voltage dividing resistor, the second voltage dividing resistor, and the third voltage dividing resistor are all involved in voltage division, the range of theoretical voltage values calculated for the conversion module to be output to the AD converter 241 (see fig. 1) is the minimum 1.60082915 volts, the maximum 2.06914185, and the range of theoretical voltage values calculated for the conversion module to be output to the AD converter 241 (see fig. 1) is the minimum 2.05409904 volts, the maximum 2.44551744 for the probe having an impedance of 22 kiloohms for the probe having an impedance of 12.1 kiloohms. It is apparent that, with the exemplary conversion module of the present invention, on the one hand, the voltage input into the AD converter is reduced, while the range of the processable voltage provided in the controller is enlarged.
In the example of fig. 3 according to the invention, the theoretical voltage Nv can be calculated according to equation (1):
where Nv represents the theoretical voltage that the calculated conversion module is to output to the AD converter, vcc is 5 volts.
In the example of fig. 3 according to the present invention, the evaluation voltage of the voltage dividing circuit including the MOSFET 322 can be calculated according to equation (2):
where EVAv is the error of the entire circuit (including the conversion module and the detection section shown in fig. 3), and Vcc is 5 volts.
In the example of fig. 3 according to the present invention, the voltage to be finally output to the AD converter is calculated according to equation (3) or equation (4):
V Detect_point ＝Nv–EVAv (3)
V Detect_point ＝Nv+EVAv (4)
wherein V is Detect_point Is the voltage actually output from the conversion module shown in fig. 3 to the AD converter.
According to a further embodiment of the invention, a detection method for a detection system is also provided. Fig. 4 is a flow chart of a detection method for a detection system comprising a detector and an analog-to-digital converter according to an example of the invention. As shown in fig. 4, in step 40, the voltage of the detection signal from the detector is adjusted by the voltage dividing circuit before the detection signal is analog-to-digital converted. In step 42, the adjusted voltage signal is converted to a digital signal. At step 44, processing is performed based on the digital signal to determine if the detected site is abnormal.
Illustratively, the adjusting the voltage of the detection signal in step 40 by the voltage dividing circuit may be achieved, for example, by the voltage dividing circuit described in any of the above examples of fig. 1, 2, 3, etc. In step 42, the signal may be digitized by, for example, the AD conversion module of FIG. 1. In step 44, it may be performed by the controller described above in connection with the example of fig. 1, etc.
It should be noted in particular that, although the conversion module, the detection system and the detection method according to the examples of the present invention are described above by taking a smoke detection system as an example, it should be understood that the conversion module, the detection system and the detection method according to the present invention may also be applied in other types of detection systems (i.e. detection systems for detecting other objects).
According to still another embodiment of the present invention, there is provided a detection system including a detection portion, and a conversion module and a back-end processing portion electrically connected to the detection portion, wherein the conversion module is a conversion module as any one of the above-described examples.
According to a further embodiment of the present invention, a detection system is provided, comprising a detector and an analog-to-digital converter, and performing a detection method for a detection system as described above in connection with fig. 4.
According to still another embodiment of the present invention, there is also provided a smoke detection system including a smoke detection portion, a conversion module electrically connected to the smoke detection portion, and a back-end processing portion, wherein the conversion module is a conversion module as any one of the above-described examples.
Although specific embodiments of the invention have been disclosed in the foregoing description with reference to the accompanying drawings, it will be understood by those skilled in the art that variations or modifications of the specific embodiments disclosed may be made without departing from the spirit of the invention. The examples of the present invention are intended to be illustrative only and are not intended to be limiting.
The examples set forth above in the present invention may be implemented either individually or in combination with each other.
Claims (7)
1. A conversion module disposed between a detector and an analog-to-digital converter, comprising:
the voltage dividing circuit is electrically connected with the detector and is used for receiving an input signal from the detector and outputting an adjusted detection signal to the analog-to-digital converter after adjusting the voltage of the input signal, wherein the voltage dividing circuit further comprises:
a switch for causing only a basic voltage dividing resistance of the voltage dividing circuit to be connected into a circuit between the detector and the analog-to-digital converter when turned off, and causing the voltage dividing circuit to be connected entirely into a circuit between the detector and the analog-to-digital converter when turned on, wherein the voltage dividing circuit includes a field effect transistor as a switch, and a first voltage dividing resistance provided between a drain of the field effect transistor and an output signal terminal of the detector, a second voltage dividing resistance provided between a gate and a source of the field effect transistor, and a third voltage dividing resistance provided between a source of the field effect transistor and an output signal terminal of the detector and serving as a basic voltage dividing resistance.
2. The conversion module of claim 1, further comprising a resistive circuit disposed between said voltage divider circuit and said analog-to-digital converter.
3. The conversion module of claim 2, further comprising:
and the follower circuit is arranged between the output end of the voltage dividing circuit and the input end of the resistance circuit.
4. A detection method for a detection system comprising a detector and an analog-to-digital converter, comprising:
before analog-to-digital conversion is carried out on the detection signal from the detector, the voltage of the detection signal is adjusted through a voltage dividing circuit;
converting the adjusted voltage signal into a digital signal;
processing based on the digital signal to determine whether the detected site is abnormal, wherein adjusting the voltage of the detection signal by the voltage dividing circuit comprises:
a switch is provided for the voltage dividing circuit such that, when the switch is turned off, only a basic voltage dividing resistor of the voltage dividing circuit is connected to a circuit between the detector and the analog-to-digital converter and, when the switch is turned on, the voltage dividing circuit is connected entirely to the circuit between the detector and the analog-to-digital converter,
the voltage dividing circuit comprises a field effect transistor serving as a switch, a first voltage dividing resistor arranged between a drain electrode of the field effect transistor and an output signal end of the detector, a second voltage dividing resistor arranged between a grid electrode and a source electrode of the field effect transistor, and a third voltage dividing resistor arranged between the source electrode of the field effect transistor and the output signal end of the detector and serving as a basic voltage dividing resistor.
5. A detection system comprising a detection portion, a conversion module electrically connected to the detection portion, and a back-end processing portion, wherein the conversion module is the conversion module according to any one of claims 1 to 3.
6. A detection system comprising a detector and an analog-to-digital converter and performing the detection method for a detection system according to claim 4.
7. A smoke detection system comprising a smoke detection portion, a conversion module electrically connected to the smoke detection portion and a back-end processing portion, wherein the conversion module is a conversion module according to any one of claims 1 to 3.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104034957A (en) * | 2014-06-11 | 2014-09-10 | 台达电子企业管理（上海）有限公司 | Power supply changeover system and voltage sampling device thereof |
| CN104034941A (en) * | 2014-06-11 | 2014-09-10 | 台达电子企业管理（上海）有限公司 | Voltage sampling system |
| CN203894320U (en) * | 2014-05-21 | 2014-10-22 | 南京信息工程大学 | Voltage measuring device |
| CN205142184U (en) * | 2015-09-17 | 2016-04-06 | 广东美的制冷设备有限公司 | Analog -to -digital conversion correction circuit, analog -to -digital conversion device and air conditioner |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006303813A (en) * | 2005-04-19 | 2006-11-02 | Nec Electronics Corp | Analog-digital conversion circuit and reference circuit |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN203894320U (en) * | 2014-05-21 | 2014-10-22 | 南京信息工程大学 | Voltage measuring device |
| CN104034957A (en) * | 2014-06-11 | 2014-09-10 | 台达电子企业管理（上海）有限公司 | Power supply changeover system and voltage sampling device thereof |
| CN104034941A (en) * | 2014-06-11 | 2014-09-10 | 台达电子企业管理（上海）有限公司 | Voltage sampling system |
| CN205142184U (en) * | 2015-09-17 | 2016-04-06 | 广东美的制冷设备有限公司 | Analog -to -digital conversion correction circuit, analog -to -digital conversion device and air conditioner |
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