Sensor system

Abstract

In a sensor system in which sensor units equipped with analog sensors are connected in series, the state of the entire sensor system is determined using the output of a single signal terminal. [Solution] The sensor system according to the present invention comprises a sensor unit formed by a pair of a sensor and a unit electronic circuit for each sensor, the switch circuits of each unit electronic circuit are connected in series, and each unit electronic circuit is configured such that all the switch circuits conduct in series when the output from all the sensors is normal.

Description

[Technical Field]

[0001] The present invention relates to a sensor system in which multiple sensors are connected. [Background technology]

[0002] A sensor system in which multiple sensors are connected in parallel to a single monitoring device allows for monitoring of each sensor without requiring complex algorithms, but it lacks scalability. Furthermore, as the system grows in size, the number of required sensors increases, leading to problems such as increased wiring and complex wiring routes.

[0003] To address these challenges, a technology exists that connects sensors in series to monitoring devices, improving scalability, cost-effectiveness, and maintainability. While there are various connection methods between monitoring devices and sensors, one example is found in Patent Document 1. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2001-067575 [Overview of the project] [Problems that the invention aims to solve]

[0005] Patent Document 1 provides a sensor system in which multiple sensors are connected in series, assuming the installation of sensors that detect on / off states. Until now, it has been difficult to accurately detect the position of a sensor that is operating in on / off mode in a system in which multiple sensors are connected in series. Here, position detection refers to the technique of identifying the position of any given sensor within a series-connected sensor system. Patent Document 1 provides a solution by transmitting and receiving pulse trains using a central monitoring device. That is, each sensor is characterized by the count value of the pulse train, and the position of the sensors is detected by processing the signals from the sensors in a time-divided manner.

[0006] However, the sensor system described in Patent Document 1 is limited to applications to sensors that detect on / off states and cannot be applied to analog sensors that detect physical changes such as temperature, pressure, and humidity and output a voltage signal proportional to the amount of change. This is because the output from analog sensors is not binary, such as on or off.

[0007] On the other hand, in analog sensor systems, for example, when a consistent process environment is required, such as in semiconductor inspection equipment, it is extremely important to keep environmental variables such as temperature, humidity, and pressure constant, as even subtle changes in environmental conditions directly affect product quality. In such situations, comprehensive monitoring of the equipment is required using analog sensors that detect changes in various physical quantities such as temperature, humidity, and pressure within the equipment and output them as electrical signals. Furthermore, since detecting an anomaly at a single point on the sensor system can affect the entire process, determining the stability of the entire sensor system takes precedence over identifying individual locations.

[0008] This invention has been made in view of the above-mentioned problems, and aims to determine the state of the entire sensor system using the output of a single signal terminal in a sensor system in which sensor units equipped with analog sensors are connected in series. [Means for solving the problem]

[0009] The sensor system according to the present invention comprises a sensor unit for each sensor, which is formed by a pair of a sensor and a unit electronic circuit. The switch circuits of each unit electronic circuit are connected in series, and each unit electronic circuit is configured such that all the switch circuits conduct in series when the output from all the sensors is normal. [Effects of the Invention]

[0010] According to the sensor system of the present invention, in a sensor system in which sensor units equipped with analog sensors are connected in series, the state of the entire sensor system can be determined using the output of a single signal terminal. [Brief explanation of the drawing]

[0011] [Figure 1] This is a block diagram of the sensor system 10 according to Embodiment 1. [Figure 2] This block shows the configuration of each sensor unit and the connections between sensor units. [Figure 3] This is a cylinder showing the configuration of a switch switching circuit. [Figure 4] This is a waveform diagram showing the relationship between each signal in Embodiment 1. [Figure 5] This is a block diagram showing the configuration of the switch switching circuit according to Embodiment 2. [Figure 6] This is a waveform diagram showing the relationship between each signal in Embodiment 2. [Modes for carrying out the invention]

[0012] <Embodiment 1> Figure 1 is a block diagram of a sensor system 10 according to Embodiment 1 of the present invention. The sensor system 10 is composed of a plurality of sensor units. Each sensor unit consists of a sensor (e.g., an analog sensor) and a unit electronic circuit. Sensor units 10-1, 10-2, 10-3, ... 10-N are electrically connected in series.

[0013] The monitoring device 1 can determine the stable or abnormal state of all sensors mounted on the sensor system 10 by monitoring the voltage value output from the first sensor unit 10-1. Furthermore, in the case of an abnormal state, it can check the output voltage of the sensor at the location where the abnormality occurred.

[0014] Here, "stable state" means that, as long as external conditions do not change, the sensor's output voltage remains constant over time and hardly fluctuates. "Abnormal state" means that the sensor's output voltage falls outside the expected range and shows unexpected fluctuations or abnormal values.

[0015] Figure 2 is a block diagram showing the configuration of each sensor unit and the connections between sensor units. The Nth sensor unit 100 is electrically connected to the (N+1)th sensor unit 101. Each sensor unit is configured with equivalent components. Using sensor unit 100 as an example, sensor unit 100 has a sensor 110 and a unit electronic circuit 111, and the unit electronic circuit 111 consists of a switch 112 (e.g., a single-pole double-headed switch) and a switch switching circuit 113. Sensor 115, unit electronic circuit 116, switch 117, and switch switching circuit 118 are configured similarly.

[0016] Switch 112 has two terminals on the input side and one terminal on the output side. One terminal on the input side is electrically connected to the output of switch 117 in the unit electronic circuit 116 of the (N+1)th sensor unit 101 (line 102), and the other terminal on the input side is connected to the output voltage V of sensor 110 of sensor unit N 100. S It is electrically connected to the following. The output side is output to the outside of the Nth sensor unit 100, and if N≧2, it is electrically connected to one terminal of the input of the switch in the unit electronic circuit of the N-1 sensor unit, and if N=1, it is electrically connected to a monitoring device, etc.

[0017] Switch 112 is the V output of the switch switching circuit 113. SWSwitches with as a trigger. V S When is in a stable state, the outputs of line 102 and switch 112 are conducting, and V S When is in an abnormal state, V S and the output of switch 112 are switched to conduct.

[0018] The switch switching circuit 113 receives, as inputs, V branched at node 114 S and a fixed voltage V having the same value as the output voltage value when sensor 110 is in a stable state REF and a threshold voltage V TH V REF and V TH will be described in detail later. V SW may be used as a trigger for switching switch 112 and does not have to be directly electrically connected to switch 112. With the above configuration, when a sensor included in an arbitrary sensor unit is in an abnormal state, the voltage value of that sensor is output from the first sensor unit, and the monitoring device checks whether the voltage value is a stable state voltage value or an abnormal state voltage value, whereby the stable state / abnormal state of the sensors mounted on each sensor unit can be discriminated.

[0019] When multiple sensors simultaneously enter an abnormal state, among the sensors in the abnormal state, the voltage value of the sensor closest to the monitoring device is transmitted to the output of the first sensor unit. When all sensors are in a stable state, since they are connected in series up to the open end of the switch included in the sensor unit farthest from the monitoring device, the output of the sensor unit becomes 0V.

[0020] Line 103 is a line that supplies power to each sensor unit. In order not to impair the merit of wiring reduction, which is one of the features of the present application, it is preferable to wire in series. Line 103 is provided separately from line 102. This is because line 102 has the role of propagating the abnormal output level from the sensor as it is, and it is not suitable to be used as a power line.

[0021] Figure 3 is a block diagram showing the configuration of the switch switching circuit. The switch switching circuit consists of a differential amplifier circuit 200A, an absolute value circuit 200B, and a comparison circuit 200C.

[0022] The differential amplifier circuit 200A includes a first operational amplifier 201, a first resistor 202, a second resistor 203, a third resistor 204, and a fourth resistor 205. One end of the first resistor 202 and the fourth resistor 205 are electrically connected to the inverting input terminal (-) of the first operational amplifier 201, one end of the second resistor 203 and the third resistor 204 are electrically connected to the non-inverting input terminal (+) of the first operational amplifier 201, and one end of the fourth resistor 205 is electrically connected to the output of the first operational amplifier 201. One end of the third resistor 204 is grounded. One end of the first resistor 202 is used to receive a fixed voltage VREF that is equal to the output voltage value when the sensor is in a stable state. One end of the second resistor 203 is connected to the output voltage V of the sensor. S It is used to receive [something]. The principle of the differential amplifier circuit 200A is well known, so a detailed explanation will be omitted here.

[0023] With the above configuration, the output of the first operational amplifier 201 is V D =(V S -V REF The output is ) × (amplification factor). This output determines the sensor's output voltage V S V REF The amount of change from can be detected. That is, V S >V REF At that time, V D The change is output as a positive voltage value, V S <V REF At that time, V D It outputs the change amount as a negative voltage value.

[0024] V REF This is an arbitrary voltage value determined by the sensor's output voltage specifications and installation environment. It may be generated by dividing the voltage supplied to the sensor unit, and can be easily adjusted for each sensor unit using a trimmer resistor.

[0025] Since the output voltage of the sensor is limited to a certain range depending on the sensor's output voltage specifications and installation environment, the amplification factor determined from the power supply of the first operational amplifier 201 and the first resistor 202 and the fourth resistor 205 may be adjusted according to the sensor's output voltage range.

[0026] The absolute value circuit 200B includes a first operational amplifier 211, a second operational amplifier 212, a first resistor 213, a second resistor 214, a third resistor 215, a fourth resistor 216, a fifth resistor 217, a first diode 218, and a second diode 219.

[0027] The inverting input terminal (-) of the first operational amplifier 211 is electrically connected to one end of the first resistor 213 and the second resistor 214, and to the cathode of the first diode 218. The non-inverting input terminal (+) of the first operational amplifier 211 is grounded. The output of the first operational amplifier 211 is electrically connected to the anode of the first diode 218 and to the cathode of the second diode 219. The anode of the second diode 219 is electrically connected to one end of the second resistor 214 and the third resistor 215. The inverting input terminal (-) of the second operational amplifier 212 is electrically connected to one end of the third resistor 215, the fourth resistor 216, and the fifth resistor 217. The non-inverting input terminal (+) of the second operational amplifier 212 is grounded. The output of the second operational amplifier 212 is electrically connected to one end of the fourth resistor 216. One end of the first resistor 213 and one end of the fifth resistor 217 are electrically connected. One end of the first resistor 213 is connected to the output voltage V of the differential amplifier circuit 200A. D It is used to receive [something]. The principle of absolute value circuits is well known, so a detailed explanation will be omitted here.

[0028] With the above configuration, V is generated from the output of the second operational amplifier 212. D The absolute value of V A This is output. DThe absolute value circuit 200B is used to invert the signal in order to operate the comparator circuit described later when a negative voltage is output to V. D Since a negative output does not affect the circuit's operation, the absolute value circuit 200B is unnecessary.

[0029] The comparison circuit 200C has a first comparator 221. The inverting input terminal (-) of the first comparator 221 is connected to the threshold voltage V, which will be described later. TH It is used to receive the output V of the absolute value circuit. The non-inverting input terminal (+) of the first comparator 221 is used to receive the output V of the absolute value circuit. A It is used to receive the voltage V used as a trigger for switching. The output of the first comparator 221 is used as a trigger for switching the switch. SW Outputs.

[0030] With the above configuration, V A <V TH At that time, V SW No output was produced, V A >V TH At that time, V SW The following is output: threshold voltage V TH V S ga V REF This voltage value determines the threshold at which the switch is flipped, and is an arbitrary fixed value determined by the sensor's output voltage specifications, installation environment, and design philosophy. It may be generated by dividing the voltage supplied to the sensor unit, and can be easily adjusted for each sensor unit using trimmer resistors.

[0031] Figure 4 is a waveform diagram showing the relationship between each signal in Embodiment 1. The upper part of Figure 4 shows the output voltage V of the sensor 110 included in the Nth sensor unit 100 shown in Figure 2. S The waveform is shown. The lower panel of Figure 4 shows the V shown in the upper panel of Figure 4. S In contrast, the output V of the switch switching circuit 113 shown in Figure 2 SW This waveform shows how they interact. REFThis is a fixed voltage input to the switch switching circuit 113 contained within the Nth sensor unit 100 shown in Figure 2. TH This indicates the threshold voltage input to the switch switching circuit 113 contained within the Nth sensor unit 100 shown in Figure 2. In Figure 4, the vertical axis represents voltage, and the direction of the arrow indicates the direction in which the absolute value of the positive voltage increases. The horizontal axis represents time, and in Figure 4, it represents the time-series change of the waveform.

[0032] Up to time t1, V S ga V REF 2V with the central axis at TH It is within the range. At this time, the sensor is judged to be in a stable state, V SW It will not be output.

[0033] During the period from time t1 to time t2, V S The voltage increases towards the positive side, V REF 2V with the central axis at TH It deviates from the range. At this time, the sensor is judged to be in an abnormal state, V SW The following will be output.

[0034] During the period from time t2 to time t3, V S V again REF 2V with the central axis at TH It falls within the range of V SW It will not be output.

[0035] During the period from time t3 to time t4, V S The voltage decreases towards the negative voltage side, V REF 2V with the central axis at TH It deviates from the range. At this time, the sensor is judged to be in an abnormal state, V SW The output is V even when the voltage decreases to the negative side. SW The output is a result of the absolute value circuit 200B being included within the switch switching circuit 113.

[0036] During the period from time t4 onward, V S V again REF 2V with the central axis at THIt falls within the range of V SW It will not be output.

[0037] <Embodiment 1: Summary> The sensor system according to Embodiment 1 includes a sensor unit for each sensor, which is formed by a pair of a sensor and a unit electronic circuit. The switch circuits of each unit electronic circuit are connected in series, and each unit electronic circuit is configured such that all switch circuits conduct in series when the output from all sensors is normal. This circuit configuration allows for inspection of sensor outputs without the use of a processing unit such as a processor. As a result, it is possible to detect that all sensor outputs are normal using a simple circuit configuration.

[0038] In the sensor system according to Embodiment 1, the unit electronic circuit switches the switch circuit to input the sensor output to the switch circuit when the output from a sensor within the same sensor unit is abnormal. As a result, when any sensor output is abnormal, the switch output from the final stage (sensor unit 10-1 in Figure 1) will be at the abnormal level of the sensor output. Therefore, it is possible to detect that any sensor output is abnormal with a simple circuit configuration.

[0039] <Embodiment 2> Embodiment 1 assumes that there is a difference between the voltage value of each sensor in a stable state and the voltage value of a sensor in an abnormal state. For example, in Embodiment 1, if the voltage value when sensor 110 is in a stable state and the voltage value when sensor 115 is in an abnormal state are the same, then the stable or abnormal state of the sensor system cannot be determined solely from the voltage value appearing at the output of the first sensor unit. Embodiment 2 of the present invention is provided as a solution to this problem.

[0040] Figure 5 is a block diagram showing the configuration of a switch switching circuit according to Embodiment 2. Since Figure 5 is similar to Figure 2, the differences will be explained mainly. The main difference is that an OR logic element is added to the unit electronic circuit in Figure 5.

[0041] The configuration shown in Figure 2 is for the output signal V SW It was used only as a trigger for switching the switch. In contrast, in Figure 5, V SW1 The signal is branched at node 120 and input to one end of the input of OR logic element 121. The other input of OR logic element 121 is electrically connected to the output of OR logic element 123 included in the (N+1)th sensor unit 101. The output of OR logic element 121 is electrically connected to one end of the input of a switch included in the unit electronic circuit of the (N-1)th sensor unit if N≧2, and to a monitoring device or the like if N=1.

[0042] With the above configuration, even if the stable state voltage value and the abnormal state voltage value are the same across sensors, it becomes possible to distinguish between stable and abnormal states by the output signal of the OR logic element. This is because when any sensor enters an abnormal state, the OR circuit in the sensor unit containing that sensor outputs a high level, and therefore the output of the final stage OR circuit also becomes a high level. However, while the switch circuit can directly propagate the abnormal output level from the sensor, the OR circuit only indicates whether or not there is an abnormality, so it is desirable to use the OR circuit as an option when the normal output level and the abnormal output level of each sensor are the same.

[0043] Figure 6 is a waveform diagram showing the relationship between each signal in Embodiment 2. The upper part of Figure 6 shows the output voltage V of the sensor 110 contained within the Nth sensor unit 100 shown in Figure 5. S1 The waveform is shown. The middle section of Figure 6 shows the output voltage V of the sensor contained within the N+1 sensor unit shown in Figure 5. S2 This shows V. The lower part of Figure 6 is V S1 , V S2 In contrast, the output V of the OR logic element 121 shown in Figure 5 OR1 This waveform shows how they interact with each other.

[0044] V REF1 This indicates the fixed voltage input to the switch switching circuit 113 in the Nth sensor unit 100 shown in Figure 5. TH1represents the threshold voltage input to the switch switching circuit 113 in the Nth sensor unit 100 shown in FIG. 5. V ERR exemplifies the voltage value when VS1 is in an abnormal state. V REF2 represents the fixed voltage input to the switch switching circuit 118 in the (N + 1)th sensor unit 101. V TH2 represents the threshold voltage input to the switch switching circuit 118 in the (N + 1)th sensor unit 101. The sensor 110 included in the Nth sensor unit 100 and the sensor 115 included in the (N + 1)th sensor unit 101 are different types of sensors, and V ERR = V REF2 is set as such.

[0045] In FIG. 6, the vertical axis represents voltage, and the direction of the arrow represents the direction in which the absolute value of the positive voltage increases. The horizontal axis represents time, and in FIG. 6, it represents the time-series change of the waveform.

[0046] Until time t1, V S1 is within the range of 2 REF1 centered on V VTH1 , and V S2 is within the range of 2V REF2 centered on V TH2 . At this time, the sensor is judged to be in a stable state, and V OR1 is not output.

[0047] During the period from time t1 to time t2, V S1 increases on the positive voltage side and deviates from the range of 2V REF1 centered on V TH1 . At this time, V S1 is transmitted to the monitoring device and V OR is also output. Since V ERR = V REF2 , the monitoring device cannot determine whether the transmitted voltage value is the voltage value when the sensor 110 is in an abnormal state or the voltage value when V S2 is in a stable state. In such a case, by reading the V OR signal, it becomes possible to discriminate between the stable and abnormal states.

[0048] That is, V OR If a signal is output, the voltage value transmitted to the monitoring device is the voltage value in the case of an abnormal condition, V OR If no signal is output, the voltage value transmitted to the monitoring device is the voltage value when the system is in a stable state.

[0049] <Embodiment 2: Summary> In the sensor system according to Embodiment 2, each unit electronic circuit is equipped with an OR circuit, and the output of the OR circuit is connected to the input of the next stage OR circuit. A signal to switch a switch circuit is input to the other input of the OR circuit. As a result, when any sensor output becomes abnormal, a signal to that effect is output from the OR circuit of the final stage (sensor unit 10-1 in Figure 1). This output from the OR circuit is always output if any sensor output is abnormal, even if the sensor output level considered abnormal differs between sensors. Therefore, in Embodiment 2, the output voltage specifications of the sensors and the sensor installation environment do not necessarily need to be uniform among the sensor units.

[0050] <Regarding variations of the present invention> The present invention is not limited to the embodiments described above, and includes various modifications. For example, the embodiments described above are described in detail for the purpose of clearly illustrating the present disclosure, and are not necessarily limited to those having all the configurations described. Furthermore, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add configurations from other embodiments to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with other configurations. [Explanation of Symbols]

[0051] 1 Monitoring device 10 Sensor Systems 10-1, 10-2, 10-3, 10-N sensor unit 110, 115 sensors 111, 116 Unit electronic circuits 112, 117 switches 113, 118 Switching Circuit 200A Differential Amplifier Circuit 200B Absolute Value Circuit 200C comparison circuit

Claims

1. A sensor system having multiple sensors, Each sensor is provided with a sensor unit formed by a pair of the aforementioned sensor and a unit electronic circuit. Each of the aforementioned unit electronic circuits includes a switch circuit, Each of the aforementioned switch circuits is connected in series. Each of the aforementioned unit electronic circuits is configured such that all of the aforementioned switch circuits conduct in series when the output from all of the aforementioned sensors is normal. A sensor system characterized by the following features.

2. The switch circuit is equipped with a first input terminal, a second input terminal, and an output terminal, and is configured to switch which of the signals input to the first input terminal or the second input terminal is output from the output terminal. The output terminal of the switch circuit is connected to the first input terminal of the switch circuit of the next stage unit electronic circuit, thereby connecting each of the switch circuits in series. The second input terminal of the sensor unit is connected to the output of the sensor of the same sensor unit. The switch circuit of the sensor unit switches the input to the first input terminal to output from the output terminal when the output from the sensor of the same sensor unit is normal. The sensor system according to claim 1, characterized in that it is as described above.

3. The switch circuit of the sensor unit switches the input to the second input terminal to output from the output terminal when the output from the sensor of the same sensor unit is abnormal. The sensor system according to claim 2, characterized in that it is as described above.

4. The aforementioned unit electronic circuit is A differential amplifier circuit that amplifies and outputs the difference between the output from the sensor and the reference signal. An absolute value circuit that outputs the absolute value of the output signal from the differential amplifier circuit. A comparison circuit that outputs the result of comparing the output signal from the absolute value circuit with a threshold voltage. Equipped with, The unit electronic circuit switches the switch circuit based on the output signal from the comparison circuit. The sensor system according to claim 2, characterized in that it is as described above.

5. The comparison circuit switches the switch circuit so that when the output signal from the absolute value circuit is less than or equal to the threshold voltage, the first input terminal and the output terminal are connected, and when the output signal is greater than the threshold voltage, the second input terminal and the output terminal are connected. The sensor system according to claim 4, characterized in that it is as described above.

6. The sensor system further includes a line that supplies power to each of the unit electronic circuits by connecting them in series, The aforementioned track is provided separately from the track that connects each of the aforementioned switch circuits in series. The sensor system according to claim 1, characterized in that it is as described above.

7. The aforementioned unit electronic circuit includes an OR logic circuit, The first input terminal of the OR logic circuit receives a switching signal to switch the switch circuit. The output terminal of the OR logic circuit is connected to the second input terminal of the OR logic circuit in the next stage unit electronic circuit, thereby connecting each of the OR logic circuits in series. The sensor system according to claim 1, characterized in that it is as described above.

8. Because each of the OR logic circuits is connected in series, when at least one of the outputs of each of the sensors is abnormal, the output of the final stage OR logic circuit is configured to output a signal indicating that at least one of the outputs of each of the sensors is abnormal. The sensor system according to claim 7, characterized in that it is as described above.

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