CN116499500A - Sensor system, sensor, signal output circuit of sensor and signal acquisition equipment - Google Patents
Sensor system, sensor, signal output circuit of sensor and signal acquisition equipment Download PDFInfo
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- G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
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Abstract
The present disclosure relates to a sensor system, a sensor, a signal output circuit thereof, and a signal acquisition device. The signal output circuit includes: a current modulation module configured to receive a sensing voltage signal representing a sensing result of the sensor and convert the sensing voltage signal into a sensing current signal; wherein the sense current signal varies with a variation of the sense voltage signal; wherein the sense voltage signal and the sense current signal are rectangular wave signals, and the sense voltage signal and the sense current signal each represent the sensing result using information related to a period of the rectangular wave signal. By utilizing the sensor signal output circuit disclosed by the invention, the system cost can be reduced, the system reliability can be improved, and the anti-interference capability of the sensor signal in the transmission process can be enhanced.
Description
Technical Field
The present disclosure relates to the field of sensors, and in particular, to a signal output circuit and a signal acquisition device related to a sensor.
Background
Currently, at least three external leads are typically required for the sensor to transmit the sensed voltage signal to the signal acquisition device, one of which is a power supply line (VDD), one of which is a voltage signal output line (OUT), and one of which is a common line (GND) that serves as both a power supply ground and a voltage signal ground, as shown in fig. 1. However, the use of more physical leads increases system cost and potential failure points, resulting in reduced system reliability, especially in applications where some sensors require the use of longer leads to transmit signals over long distances. In addition, particularly in the case of a remote transmission signal, the voltage signal output from the sensor is easily disturbed and easily attenuated.
Currently, some existing technologies convert the voltage signals of the sensor collected by the singlechip into current signals, but the current signals convert the square wave voltage signals with different duty ratios into direct current voltage signals, and then convert the direct current voltage signals into direct current signals, so that the direct current signals are particularly easy to be interfered in the transmission, conversion and other processes, and the accuracy of the final detection result is affected. In addition, the existing scheme converts the sensor signals acquired by the signal acquisition equipment, but does not convert the sensor output signals before the acquisition of the signal acquisition equipment, so that the number of external leads of the sensor cannot be reduced.
Thus, it is desirable to improve the signal processing of the sensor.
Disclosure of Invention
One technical problem to be solved by the present disclosure is to provide a better signal processing method of a sensor.
According to a first aspect of the present disclosure, there is provided a signal output circuit for a sensor, comprising: a current modulation module configured to receive a sensing voltage signal representing a sensing result of the sensor and convert the sensing voltage signal into a sensing current signal; wherein the sense current signal varies with a variation of the sense voltage signal; wherein the sense voltage signal and the sense current signal are rectangular wave signals, and the sense voltage signal and the sense current signal each represent the sensing result using information related to a period of the rectangular wave signal.
Optionally, the sense current signal has the same periodic variation as the sense voltage signal.
Optionally, the information related to the period of the rectangular wave signal includes an absolute duration of the period, a duty cycle, a ratio between adjacent period durations, or a ratio between differences of adjacent period durations.
Optionally, the current modulation module is configured to output a first current if the sensing voltage signal is at a high level and to output a second current smaller than the first current or not if the sensing voltage signal is at a low level, thereby outputting the sensing current signal with a first current value at a high level and a second current value at zero current or at a low level.
Optionally, the current modulation module comprises a constant current source with a switch, wherein the switch is configured to be turned on or off according to a level of the sense voltage signal being high or low, and wherein the constant current source is configured to output a constant current if the switch is turned on and to output no current or a constant smaller current if the switch is turned off, whereby an output of the constant current source constitutes the sense current signal.
Optionally, a sum of the sensed current signal and a substantially constant current is output as an output signal of the sensor.
According to a second aspect of the present disclosure, there is provided a sensor comprising: a sensing section configured to obtain a sensing voltage signal representing a sensing result thereof; and a signal output circuit according to the first aspect of the present disclosure; the sensor comprises two external terminals respectively used for receiving power supply voltage and ground, and current flowing between the two external terminals is used as an output signal of the sensor.
According to a third aspect of the present disclosure, there is provided a signal acquisition device for a sensor, comprising: one or more demodulation modules configured to receive output signals of one or more sensors according to the second aspect of the present disclosure, respectively, and to convert the output signals into demodulation voltage signals that are identical to or proportional to the sensing voltage signals of their corresponding sensors.
Optionally, the output signal of at least one of the one or more sensors is a rectangular wave signal, and the sensing result is represented with information related to a period of the rectangular wave signal; wherein the demodulation module corresponding to the at least one sensor includes a current detection circuit having a comparator configured to detect a current value of the output signal and compare the current value of the output signal with a threshold value of the comparator, thereby outputting the demodulation voltage signal as a rectangular wave signal, wherein the demodulation voltage signal is at a high level for a period in which the current value of the output signal is higher than the threshold value and at a low level for a period in which the current value of the output signal is lower than the threshold value.
According to a fourth aspect of the present disclosure, there is provided a sensor system comprising: one or more sensors according to the second aspect of the present disclosure; a signal acquisition device; wherein the signal acquisition device comprises one or more demodulation modules configured to receive output signals of the one or more sensors, respectively, and to convert the output signals into demodulated voltage signals that are identical to or proportional to the sensed voltage signals of their corresponding sensors.
Optionally, the sensor system further comprises a multiplexer, wherein the multiplexer selectively transmits one of the output signals of the plurality of sensors to one demodulation module, such that the plurality of sensors can share one demodulation module.
Therefore, by utilizing the signal output circuit provided by the disclosure, the number of external leads of the sensor for transmitting signals can be reduced, so that the system cost is reduced and the system reliability is improved. In addition, due to the adoption of the signal output circuit, the carrier of the output signal of the sensor becomes current, so that compared with a voltage signal, the anti-interference capability of the current output signal is stronger and is less easy to attenuate, and particularly in the case of long-distance transmission.
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The foregoing and other objects, features and advantages of the disclosure will be apparent from the following more particular descriptions of exemplary embodiments of the disclosure as illustrated in the accompanying drawings wherein like reference numbers generally represent like parts throughout exemplary embodiments of the disclosure.
Fig. 1 shows a schematic diagram of a sensor and its external leads according to the prior art.
Fig. 2 shows a schematic composition of a sensor according to one embodiment of the present disclosure.
Fig. 3A-3C illustrate some waveform examples of a sense voltage signal of a sensor according to some embodiments of the present disclosure, respectively.
Fig. 4A-4C illustrate waveform examples of a sense voltage signal, a sense current signal, and a sensor output signal, respectively, according to one embodiment of the present disclosure.
Fig. 5 shows a schematic composition diagram of a current modulation module according to one embodiment of the present disclosure.
Fig. 6 shows a schematic composition diagram of a signal acquisition device according to one embodiment of the present disclosure.
Fig. 7A and 7B illustrate waveform examples of a sensor output signal and its corresponding demodulation voltage signal received by a signal acquisition device according to one embodiment of the present disclosure, respectively.
Fig. 8 shows a schematic diagram of the composition of a sensor system employing a multiplexed sensor and corresponding signal acquisition device according to one embodiment of the present disclosure.
Fig. 9 shows a schematic diagram of a sensor system employing a multiplexed sensor and corresponding signal acquisition device according to another embodiment of the present disclosure.
Detailed Description
Preferred embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While the preferred embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
As described above, in response to the problems with the prior art sensor such as that shown in fig. 1, the present disclosure proposes an improved signal output circuit for a sensor, which changes the carrier of the output signal of the sensor from voltage to current, thereby reducing the number of external leads of the sensor for transmitting signals, thereby reducing system cost and improving system reliability, and enhancing the anti-interference capability of the output signal, thereby improving accuracy in the acquisition of the back-end signal. The inventive concept will be explained in more detail below in connection with embodiments of the present disclosure illustrated in the accompanying drawings.
Fig. 2 shows a schematic composition of a sensor according to one embodiment of the present disclosure.
As shown in fig. 2, in some embodiments, the sensor may include a sensing portion 210 and a signal output circuit 220.
The sensing part 210 may be configured to obtain a sensing voltage signal V representing a sensing result thereof S . Herein, the "sensing result" refers to a non-electric quantity (such as various physical quantities, chemical quantities, or biological quantities, etc.) sensed by the sensor, and the "sensing voltage signal" or the "sensing current signal" refers to a voltage signal or a current signal that may be used to represent the sensing result of the sensor. For example, the sensing part 210 may generally include a sensing element for directly sensing a measured non-electric quantity (e.g., various physical quantities, chemical quantities, or biological quantities, etc.), and a conversion circuit for converting a state change of the sensing element corresponding to the measured non-electric quantity into a sensing voltage signal, or may include a sensing circuit capable of directly converting the sensed measured non-electric quantity into the sensing voltage signal. Those skilled in the art will appreciate that the present invention is not limited to a certain type of sensor, but is applicable to all sensors that need to output an electrical signal as a sensing result.
The signal output circuit 220 may be used for the sensing voltage signal V obtained for the sensing part 210 S Corresponding signal processing is performed to facilitate transmission of sensor signals and/or subsequent acquisition operations, etc. Since the present invention proposes a novel signal output method for changing the carrier of the output signal of the sensor from voltage to current, the present invention adds a current modulation mode as shown in FIG. 2 to the signal output circuit 220Block 221 senses the voltage signal V S And carrying out current modulation processing. In the present disclosure, "current modulation" refers to a change made to a signal carrier in order to transmit a signal, i.e., changing the carrier of a signal to be transmitted from voltage to current, and "demodulation" refers to the inverse of "modulation", i.e., restoring a received current signal to a voltage signal. Those skilled in the art will appreciate that the present invention is not limited to the exemplary configuration of the signal output circuit 220 shown in fig. 2 described above. For example, although not shown, in some other embodiments, the signal output circuit 220 may also include other circuits besides the current modulation module 221, such as a sense current signal I for output to the current modulation module 221, as desired for a practical application S And a circuit for performing further adjustment (for example, amplification). The signal output circuit 220 may be integrated on one chip with the sensing part 210 or other circuits of the sensor, or may be separately manufactured on a separate chip or component, so that an existing sensor transmitting a sensing voltage signal may be easily retrofitted into a current-signal transmission carrier sensor according to the present invention by adding the chip or component of the signal output circuit 220 to the existing sensor.
As shown in fig. 2, in some embodiments, the current modulation module 221 is configured to receive a sensing voltage signal V output by the sensing part 210 and representing a sensing result of the sensor S And will sense the voltage signal V S Conversion to a sense current signal I S Wherein the sense current signal I S With the sensed voltage signal V S Is changed by a change in (a). For example, in sensing voltage signal V S In the case of a conventional analog signal and representing the sensing result by the amplitude of the voltage, the current signal I is sensed S Can also be a conventional analog signal and its current amplitude can be followed by the sensed voltage signal V S Varying with variation of voltage amplitude, e.g. sensing current signal I S Can be correlated with the sense voltage signal V S Is proportional to the voltage amplitude of (a) so that the sense current signal I can be used S To represent the sensed result. In addition, for example, as will be detailed laterIn the sense voltage signal V S In the case of using analog signals in the form of time-domain signal expression and representing the sensing result with time-related information, the current signal I is sensed S Or an analog signal expressed by a time domain signal, and the high/low level of the current amplitude of the analog signal follows the sensing voltage signal V S The high/low level of the voltage amplitude of (a) is changed, that is, the corresponding current amplitude is high when the voltage amplitude is high, and the corresponding current amplitude is low when the voltage amplitude is low, wherein the values of the high/low level of the voltage signal and the current signal can be set according to practical application conditions. The sense current signal I thus converted S Is provided with and senses the voltage signal V S The same time-varying rectangular wave, thereby becoming indicative of the sensing result with time-dependent information of the sensed current signal.
In addition, as shown in FIG. 2, in some embodiments, the sensor may have only two external terminals VDD and GND for receiving a power supply voltage and ground, respectively, and may be configured to pass a current I between the two external terminals O As an output signal of the sensor. Therefore, compared with fig. 1 in the prior art, the invention can omit the voltage signal output line OUT in fig. 1 by adding a current modulation module, thereby changing the three-wire connection mode of the sensor transmission signal into a two-wire connection mode.
In the embodiment shown in fig. 2, the output signal I of the sensor O Can be the sense current signal I S And the current I flowing through the sensing part 210 1 And (3) summing. The current I flowing through the sensing portion 210 can be designed to 1 Substantially constant, i.e. with its current amplitude constant over time or with its current amplitude fluctuating over time relative to the sensed current signal I S The current amplitude (e.g., the voltage difference between the high and low levels of the rectangular wave) may be negligible (e.g., by 1 or more orders of magnitude) or may not affect subsequent sensor signal processing. The output signal I of the sensor can also be said to be O Is the sense current signal I S And a substantially constant current. Therefore, the output signal of the sensor corresponds to sense onlyCurrent measuring signal I S The DC bias is added to still show the sensing current signal I S And carrying the sensing result information. Those skilled in the art will appreciate that in other embodiments, in addition to the current modulation module 221 and the sensing portion 210 shown in FIG. 2, the sensor may include other circuitry that consumes current (i.e., current flowing therethrough) that is also the output signal I of the sensor O Thereby, with the above-mentioned current I 1 Similarly, the total current of the sensor (i.e. output signal I O ) Medium-divide sense current signal I S The other current portions may be designed to be substantially constant currents.
The embodiment of the present invention shown in fig. 2 described above will be more clearly illustrated below with an example of an analog signal using a time domain signal expression as a sense voltage signal and a sense current signal.
In some embodiments, the sensor may include a circuit module to convert a conventional analog signal to an analog signal in a time domain signal representation, such that information originally represented by the amplitude of the analog signal (e.g., the sensing result) is converted to be represented by time. Such time domain signals are concerned with time information and not with signal amplitude variations, compared to conventional analog sensing signals in which the sensing result is represented by signal amplitude, thus further enhancing the anti-interference capability of the sensor signal. Of course, the disclosure is not limited thereto, but the sensing result may be expressed by directly obtaining an analog signal in a time domain signal expression mode according to the measured non-electric quantity of the sensor.
FIGS. 3A-3C respectively illustrate sense voltage signals V of sensors according to some embodiments of the present disclosure S In which a voltage signal V is sensed S Is an analog signal using a time domain signal representation.
In some possible implementations, the time domain signal representation of the analog signal can be classified into two categories: 1) Expressing information (e.g., the foregoing sensing results) using the absolute time length of the period; 2) The information is expressed using a proportional relationship of the period. The second proportional relation time domain expression can comprise two expressions of duty ratio of each period and adjacent period proportion.
Specifically, as shown in fig. 3A, when the time domain signal is expressed in terms of the absolute period length of the period, the magnitude of the period T may express information of the signal, for example, the magnitude of the conventional analog signal may be converted into the magnitude of the period T in proportion thereto. As shown in FIG. 3B, when the time domain signal is expressed with each periodic duty cycle, the duty cycle may express information of the signal, e.g., proportional to the magnitude of the conventional analog signal, i.e.Where TH represents a high-level duration and TL represents a low-level duration. As shown in fig. 3C, when the time domain signal is expressed in proportion to adjacent periods, the proportion between adjacent period durations or the proportion between adjacent period duration differences may express information of the signal, for example, in proportion to the magnitude of the amplitude of a conventional analog signal, i.e., ->Or->Wherein T1, T2, T3 each represent an adjacent 3 period duration. Of course, those skilled in the art will understand that the present invention is not limited to the above-mentioned case of proportionally converting the amplitude of the analog signal into the corresponding period-related information, and other manners may be adopted to convert the measured or the analog signal representing the measured into the corresponding period-related information, as long as there is a mapping relationship between the two.
In some embodiments, the sense voltage signal V of the sensor S May be a rectangular wave signal, and the sense voltage signal V S The sensing result is represented by information related to the period of the rectangular wave signal. For example, the sensing result may be represented by information related to the period, such as an absolute period length of the period, a duty ratio, a ratio between adjacent period lengths, or a ratio between differences between adjacent period lengths. Also, the voltage signal V is sensed as described above S Converted sense current signal I S Is provided with and is connected withSensing voltage signal V S The same periodic rectangular wave signal, and also the sensing result is represented by its periodic related information.
In the embodiment shown in fig. 2, the signal shown in fig. 4A (having a waveform similar to that shown in fig. 3C) is used as the sense voltage signal V S For example, the sensed current signal I obtained by conversion of the current modulation module S Follow the sense voltage signal V S The waveform of which is shown in FIG. 4B, and the output signal I of the sensor O As shown in fig. 4C. In the drawings, respectively by "V SH "AND" I SH "to represent the sense voltage signal V S High level voltage value of (1) and sense current signal I S The low level value of both of these are indicated by "0". As previously described, the output signal I of the sensor O To sense the current signal I S And a substantially constant current I flowing through the sensing portion 210 1 The sum of the output signals of the sensors is therefore O Is of the high level current value I OH =I 1 +I SH 。
In embodiments where the sense voltage signal is implemented using various time domain signal expressions of analog signals as described above, in some cases, the current modulation module may be configured to output a first current if the sense voltage signal is high and to output a second current or no current smaller than the first current if the sense voltage signal is low, thereby outputting a sense current signal with the first current value being high and the second current value being zero or low. For example, different constant current sources may be turned on, off, or selected using the high-low level state of the sensing voltage signal, thereby achieving current modulation; thereby turning on the constant current source in the case where the sensing voltage signal is at a high level, thereby outputting a constant current generated by the constant current source, which may correspond to the aforementioned first current, and turning off the constant current source or selecting a smaller (smaller than the aforementioned first current) constant current source in the case where the sensing voltage signal is at a low level, i.e., outputting no current or outputting a smaller constant current.
NamelyThat is, in some embodiments, the current modulation module 221 as shown in FIG. 2 may include a constant current source with a switch, wherein the switch is responsive to the sense voltage signal V S Is turned on or off by being high or low, and the constant current source outputs a constant current I when the switch is turned on SH While in the case of the switch being opened, there is no current output, or another smaller constant current source is selected, outputting a smaller constant current. Whereby the output of the constant current source constitutes the sense current signal I S Which follows the sense voltage signal V S And the high level is I SH While the low level is 0 or less current. Fig. 5 below shows a simple implementation of the above-described current modulation module 221 by way of example only. Those skilled in the art will appreciate that the present invention is not limited thereto, and that various analog circuits are known to be used to implement the switched constant current source.
As shown in fig. 5, the current modulation module 221 may include an NMOS transistor M1 and a resistor R1, wherein a gate of the NMOS transistor M1 is driven by the sense voltage signal V S The drain of the NMOS transistor M1 is coupled to the supply voltage VDD and the source is coupled to one end of the resistor R1, the other end of the resistor R1 is coupled to ground GND. When sensing the voltage signal V S The NMOS transistor M1 is turned on when the voltage is high, and the NMOS transistor M1 and the resistor R1 connected in series between the power supply voltage VDD and the ground GND generate a constant current, so the constant current I can be outputted when the constant current source is turned on SH . While sensing the voltage signal V S When the NMOS transistor M1 is at the low level, it is not turned on, and at this time, an open circuit is formed between the power supply voltage VDD and the ground GND, and no current flows, so that it can be regarded that the constant current source is turned off and no current is outputted. Thus, the NMOS transistor M1 and the resistor R1 constitute a constant current source with a switch.
In addition, since the sensor according to the invention changes the carrier transmitting the signal from voltage to current, the signal acquisition device which acquires the signal of the sensor at the acquisition end and performs subsequent processing is also improved correspondingly.
Fig. 6 shows a schematic composition diagram of a signal acquisition device according to one embodiment of the present disclosure.
As shown in fig. 6, in some embodiments, a demodulation module (e.g., current detection circuit 621 shown in the figure) may be added to the signal acquisition device 620 to convert the received output signal I of the sensor 610 O Is restored to voltage signal V O . Restoring the obtained voltage signal V O May be referred to as a demodulation voltage signal that is the same as or proportional to the sense voltage signal before the corresponding sensor 610 current modulates. The demodulation module example in fig. 6 may be applied to the sensor example of sensing the voltage/current signal expressed using the period information as described above, and thus, demodulating the voltage signal V O Is the sensed voltage signal V of the sensor 610 S And sensing a current signal I S The values of the high/low levels of the rectangular wave signals whose period changes the same may be set according to actual needs.
In the embodiment shown in fig. 6, the demodulation module includes a current detection circuit 621 having a comparator 622. The current detection circuit 621 is configured to detect a current value of an output signal of the sensor and compare the current value with a threshold value of the comparator 622, thereby outputting a demodulated voltage signal V as a rectangular wave signal O In which the voltage signal V is demodulated O The current value is high during a period when the current value is above the threshold value and low during a period when the current value is below the threshold value. Those skilled in the art will appreciate that the present invention is not limited to the implementation of the demodulation module or the current detection circuit 621 with the comparator 622, but may be implemented in various ways, for example, in a circuit manner similar to the overcurrent detection. In addition, although not shown in fig. 6, it will be understood by those skilled in the art that the signal acquisition device 620 may further include other circuits besides the demodulation module, such as an analog-to-digital conversion circuit, a calculation communication circuit, and the like, which are not described herein.
To more clearly illustrate the demodulation process of fig. 6, fig. 7A and 7B respectively show waveform examples of the sensor output signal and its corresponding demodulation voltage signal received by the signal acquisition device according to one embodiment of the present disclosure.
In the ideal transmission case, the sensor output signal received by the signal acquisition device 620 shown in fig. 7A is the same as the transmitted sensor output signal shown in fig. 4C. Even in view of signal disturbances that may be present during transmission, the amplitude variation of the received current signal is typically much smaller than the difference between the high and low levels of the current signal and thus has no effect on the subsequent current detection and comparison process, whereby fig. 7A shows only the current signal received in an ideal case for simplicity. The rectangular wave signal is compared by a threshold value (for example, an average value of high and low levels of a current signal to be detected) set by a comparator 622 in the current detection circuit 621: outputting a demodulation voltage signal V when the threshold value is higher O Is of high level V OH I.e. logic digital 1, outputs a demodulation voltage signal V when it is below the threshold value O Is low, i.e., a logical digital 0, as shown in fig. 7B.
In addition, the invention is suitable for signal acquisition equipment for processing single-channel sensor signals and also suitable for signal acquisition equipment for processing multi-channel sensor signals. That is, the invention has very good expansibility, and can realize the signal processing of the multichannel sensor by adding a multipath demodulation module (for example, as shown in fig. 8) in the signal acquisition equipment, and change the three-wire wiring mode of the signals of the multichannel sensor into a two-wire wiring mode.
Fig. 8 shows a schematic diagram of the composition of a sensor system employing a multiplexed sensor and corresponding signal acquisition device according to one embodiment of the present disclosure.
As shown in fig. 8, the overall sensor system may include n-way sensors 811-81n and corresponding signal acquisition devices 820 that acquire the n-way sensor signals. These sensors 811-81n may employ a signal output circuit as described above to use current as a carrier for transmitting signals, while the signal acquisition device 820 may include n corresponding demodulation modules 821-82n that convert received sensor signals into demodulation voltage signals V as described above O1 -V On . At least one of the sensors 811-81n may use the periodic related information of the rectangular wave signal as described above to express the sensing resultThe demodulation module corresponding to the at least one sensor may thus adopt the structure of fig. 6 as described above.
For example, in the sensor system requiring n sensor signals as shown in fig. 8, by implementing the signal modulation and demodulation processing method of the present invention, n physical leads can be reduced, the cost of the multi-channel sensor system can be greatly reduced, potential failure points can be reduced, and the reliability of the multi-channel sensor system can be improved.
Fig. 9 shows a schematic diagram of a sensor system employing a multiplexed sensor and corresponding signal acquisition device according to another embodiment of the present disclosure.
The difference between fig. 9 and fig. 8 is mainly that the output signals of n sensors are combined into one path by using a multiplexer, so that a demodulation module can be shared, and the hardware cost is saved.
Specifically, as shown in FIG. 9, the overall sensor system may include n-way sensors 911-91n and a corresponding signal acquisition device 920 that acquires the n-way sensor signals. These sensors 911-91n may employ signal output circuitry as previously described to use the current as a carrier for transmitting the signal, while the signal acquisition device 920 may include a multiplexer 930 and demodulation module 940. Multiplexer 930 may selectively couple one of the n sensor output signals I O1 /I O2 /…/I On To a demodulation module 940, which demodulation module 940 transmits the received sensor signal I as described above O1 /I O2 /…/I On Converted into a demodulation voltage signal V O1 /V O2 /…/V On . The multiplexer 930 may sequentially transmit the n sensor signals to the demodulation module 940 in order or transmit specific sensor information to the demodulation module 940 as needed. At least one of the sensors 911-91n may use the period related information of the rectangular wave signal as described above to express the sensing result, and thus the demodulation module 940 may use the structure of fig. 6 as described above. As mentioned above, the present invention provides a novel method for modulating and demodulating sensor signals, which changes the three-wire connection mode of the transmission signals through a current modulation moduleThe method is changed into a two-wire connection mode, and particularly in the application field of processing signals of multiple sensors and remotely transmitting signals, the method can greatly reduce the connection cost of the system. The cost reduction of the multi-channel sensor chip set will be more significant.
In addition, due to the reduction of the number of the signal lines, potential fault points of the system are reduced, the reliability of the system is improved, and the performance of the system is improved, particularly in the field of multi-path sensing signal application, more remarkable performance improvement is brought.
In addition, the invention changes the carrier for transmitting signals of the sensor from voltage to current, thereby increasing the resistance to interference. The anti-interference capability of the voltage signal is weak, and the voltage value deviation of the wire terminal is large and easy to attenuate during long-distance transmission; the magnitude of the current signal is only related to the signal source, is not related to the resistance of the transmission wire, and is not influenced by the distributed capacitance. Therefore, the carrier for transmitting the signal is changed from voltage to current through the current modulation module, and the anti-interference capability of the signal is improved.
The foregoing description of embodiments of the invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the various embodiments described. The terminology used herein was chosen in order to best explain the principles of the embodiments, the practical application, or the improvement of technology in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.
Claims (11)
1. A signal output circuit for a sensor, comprising:
a current modulation module configured to receive a sensing voltage signal representing a sensing result of the sensor and convert the sensing voltage signal into a sensing current signal;
wherein the sense current signal varies with a variation of the sense voltage signal;
wherein the sense voltage signal and the sense current signal are rectangular wave signals, and the sense voltage signal and the sense current signal each represent the sensing result using information related to a period of the rectangular wave signal.
2. The signal output circuit of claim 1, wherein the sense current signal has the same periodic variation as the sense voltage signal.
3. The signal output circuit of claim 1, wherein the information related to the period of the rectangular wave signal includes an absolute duration of the period, a duty cycle, a ratio between adjacent period durations, or a ratio between differences of adjacent period durations.
4. The signal output circuit according to claim 1, wherein the current modulation module is configured to output a first current if the sense voltage signal is high level and to output a second current smaller than the first current or not if the sense voltage signal is low level, thereby outputting the sense current signal with a first current value being high level and a second current value being zero current or low level.
5. The signal output circuit of claim 4 wherein said current modulation module comprises a switched constant current source,
wherein the switch is configured to be turned on or off according to the level of the sensing voltage signal, and
wherein the constant current source is configured to output a constant current with the switch on and no current output or a constant smaller current with the switch off, whereby the output of the constant current source constitutes the sense current signal.
6. The signal output circuit according to any one of claims 1 to 5, wherein a sum of the sense current signal and a substantially constant current is output as an output signal of the sensor.
7. A sensor, comprising:
a sensing section configured to obtain a sensing voltage signal representing a sensing result thereof; and
the signal output circuit according to any one of claims 1 to 6;
the sensor comprises two external terminals respectively used for receiving power supply voltage and ground, and current flowing between the two external terminals is used as an output signal of the sensor.
8. A signal acquisition device for a sensor, comprising:
one or more demodulation modules configured to receive the output signals of one or more sensors according to claim 7, respectively, and to convert the output signals into demodulation voltage signals that are identical to or proportional to the sense voltage signals of their corresponding sensors.
9. The signal acquisition device of claim 8, wherein the output signal of at least one of the one or more sensors is a rectangular wave signal and the sensing result is represented with information related to a period of the rectangular wave signal;
wherein the demodulation module corresponding to the at least one sensor includes a current detection circuit having a comparator configured to detect a current value of the output signal and compare the current value of the output signal with a threshold value of the comparator, thereby outputting the demodulation voltage signal as a rectangular wave signal, wherein the demodulation voltage signal is at a high level for a period in which the current value of the output signal is higher than the threshold value and at a low level for a period in which the current value of the output signal is lower than the threshold value.
10. A sensor system, comprising:
one or more sensors according to claim 7; and
a signal acquisition device;
wherein the signal acquisition device comprises one or more demodulation modules configured to receive output signals of the one or more sensors, respectively, and to convert the output signals into demodulated voltage signals that are identical to or proportional to the sensed voltage signals of their corresponding sensors.
11. The sensor system of claim 10, further comprising a multiplexer,
wherein the multiplexer selectively transmits one of the output signals of the plurality of sensors to one demodulation module so that the plurality of sensors can share the one demodulation module.
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