TWI652450B - Signal detecting device - Google Patents

Abstract

The invention discloses a signal detecting device. The device comprises: a power terminal, a signal receiving end, a signal transmitting end, a control end and a detecting circuit, wherein the detecting circuit comprises a first end, a second end and a third end, wherein the first end is connected to the power end; the second end is connected Between the signal receiving end and the signal transmitting end; the third end is connected to the control end, and the control end is configured to receive the control signal. When the control signal is in the first state, the resistance value between the first end and the second end is a resistance value, when the control signal is in the second state, the resistance value between the first end and the second end is a second resistance value, wherein the first resistance value and the second resistance value are not equal. The signal detecting device solves the problem that the resistance signal caused by the separation in the prior art is affected by the ground voltage difference, and achieves the technical effect of accurately detecting the resistance value to be measured represented by the resistance signal.

Description

Signal detecting device

The present invention relates to the field of signal detection, and in particular to a signal detecting apparatus.

The vehicle sensor is an input device of the in-vehicle electronic control system for sensing information of various working conditions in the operation of the motor vehicle, such as the speed of the vehicle, the temperature of each medium, the operating conditions of the engine, etc., and converts the information into electricity. Signals are sent to the control system to keep the vehicle in optimal working order. Among them, the sensor of the oil pressure sensor, water temperature sensor and air temperature sensor usually works by using a resistive sensitive component such as a varistor or a thermistor to convert the corresponding measured value into a resistance. The value signal is sent out through the output of the sensor, which is used to represent the resistance value between the sensor output and the sensor ground. Therefore, accurately detecting the resistance value of the resistance signal sent by the resistance sensor is an important part of vehicle control.

In the prior art, the above resistance value signal is usually directly collected by a data acquisition module such as a microprocessor. In this mode of operation, the premise that the resistance value to be measured represented by the resistance signal is accurately detected is that the transmitting device of the resistance signal is shared with the collecting device. For example, for vehicle control, each sensor and vehicle are required. The data acquisition module in the electronic control system is common. However, in the case where the vehicle body ground is separated from the sensor, There is usually a voltage difference between each of the above sensors and the ground of the data acquisition module. In this case, the resistance signal input to the processor is usually affected by the voltage difference between the above grounds, so that the resistance value to be measured cannot be accurately represented. In addition to the field of vehicle control, the above problems are still widely found in the field of signal detection.

In response to the above problems, no effective solution has been proposed yet.

The embodiment of the invention provides a signal detecting device to solve at least the problem that the resistance signal caused by the ground separation in the prior art is affected by the ground voltage difference.

In order to solve the above technical problem, the signal detecting apparatus of the present invention includes: a power terminal, a signal receiving end, a signal transmitting end, a control end, and a detecting circuit, wherein the detecting circuit includes a first end, a second end, and a third end, wherein The first end is connected to the power end, the power end is used for connecting to the power source, and the voltage between the power source and the first ground is constant; the second end is connected between the signal receiving end and the signal sending end, and the signal receiving is The terminal is configured to receive a resistance value, wherein the resistance signal is used to indicate a resistance value to be measured between the signal receiving end and the second ground, and the signal transmitting end is configured to send a voltage signal, and the voltage signal is used to indicate the signal sending. a voltage value between the terminal and the first ground, wherein a voltage difference exists between the first ground and the second ground; the third end is connected to the control end, and the control terminal is configured to receive a control signal, when When the control signal is in the first state, the resistance between the first end and the second end is a first resistance value, and when the control signal is in the second state In the state, the resistance value between the first end and the second end is a second resistance value, wherein the first resistance value and the second resistance value are not equal.

Preferably, the signal detecting device further includes: a processor, wherein an input end of the processor is connected to the signal sending end, and configured to be configured to be configured according to the first resistance value, the second resistance value, the first voltage value, and the second voltage The value of the resistance to be measured is obtained, wherein the first voltage value is a voltage value of the voltage signal when the control signal is in the first state, and the second voltage value is a voltage signal when the control signal is in the second state Voltage value.

Preferably, the processor is configured to obtain the resistance value to be tested according to the following formula:

Wherein R is used to represent the resistance value to be tested, E is used to indicate the voltage value of the power source relative to the first ground, _{V_on is} used to represent the first voltage value, and _{V_off is} used to represent the second voltage value. Z _{_on is} used to indicate the above first resistance value, and Z _{_off is} used to represent the above second resistance value.

Preferably, the output end of the processor is connected to the control terminal for transmitting the control signal to the control terminal.

Preferably, the detecting circuit includes: a switch circuit and a first resistor, wherein the switch circuit and the first resistor are connected in series or in parallel between the first end and the second end, wherein the switch The control input end of the circuit is connected to the third end, and when the control signal is in the first state, the switch circuit leads Preferably, when the control signal is in the second state, the switch circuit is turned off.

Preferably, the detecting circuit further includes: a second resistor, when the switching circuit and the first resistor are connected in series between the first end and the second end, the second resistor is opposite The combination of the switching circuit and the first resistor is connected in parallel between the first end and the second end, and the switching circuit and the first resistor are connected in parallel to the first end And between the second end, the second resistor is connected in series between the first end and the second end with respect to the combination of the switch circuit and the first resistor.

Preferably, the detecting circuit further comprises: one or more third resistors connected in parallel at opposite ends of the first resistor.

Preferably, the signal detecting device includes: a heat dissipating mechanism adjacent to the first resistor and the third resistor.

Preferably, the above switching circuit comprises a transistor switching circuit.

Preferably, the detecting circuit further comprises at least one of: a current limiting component connected between the second end and the signal transmitting end; a pull-up resistor, one end of the pull-up resistor being connected to the second end and the above Between the signal transmitting ends, the other end of the pull-up resistor is connected to the power terminal; the clamp unit circuit, one end of the clamp circuit is connected between the second end and the signal sending end, and the clamp circuit The other end is connected to the first ground, and the other end of the clamp circuit is connected to the power terminal; the first capacitor is the first capacitor One end is connected between the second end and the signal transmitting end, the other end of the first capacitor is used to connect the first ground; the second capacitor is connected to one end of the second capacitor at the signal receiving end and the second Between the ends, the other end of the second capacitor is used to connect the first ground; the fourth resistor, one end of the fourth resistor is connected between the signal receiving end and the second end, the fourth resistor The other end is used to connect the first ground described above.

In the embodiment of the present invention, the partial pressure between the equivalent resistance formed by the detection circuit and the equivalent resistance value corresponding to the resistance value received by the detection circuit is passed through the first state. Acquiring the resistance value of the equivalent resistance formed by the detecting circuit in the second state and the voltage value across the equivalent resistance formed by the detecting circuit, thereby realizing the accurate detection of the above-mentioned resistance signal The technical effect of measuring the resistance value further solves the technical problem that the resistance signal is affected by the voltage difference existing between the first ground and the second ground.

102‧‧‧Signal receiving end

104‧‧‧Signal sender

106‧‧‧Control end

108‧‧‧Power terminal

110‧‧‧Detection circuit

112‧‧‧ first end

114‧‧‧second end

116‧‧‧ third end

120‧‧‧Switch circuit

122‧‧‧Transistor

130‧‧‧First resistor

132‧‧‧second resistor

134‧‧‧ third resistor

136‧‧‧ equivalent resistance

140‧‧‧ Current limiting components

142‧‧‧ Pull-up resistor

144‧‧‧First capacitor

146‧‧‧second capacitor

148‧‧‧fourth resistor

150‧‧‧ clamp element circuit

160‧‧‧heating mechanism

180‧‧‧ processor

The drawings described herein are intended to provide a further understanding of the invention, and are intended to be a part of the invention. In the drawings: FIG. 1 is a preferred circuit diagram of a signal detecting apparatus according to an embodiment of the present invention; and FIG. 2 is a schematic diagram of a signal detecting apparatus according to an embodiment of the present invention; 3 is another preferred schematic diagram of a signal detecting apparatus according to an embodiment of the present invention; and FIG. 4 is a comparison of a preferred connection manner between a signal detecting apparatus and a transmitting apparatus of a resistance value according to an embodiment of the present invention. FIG. 5 is a preferred circuit diagram of a detection circuit of a signal detection apparatus according to an embodiment of the present invention; FIG. 6 is another preferred circuit diagram of a detection circuit of a signal detection apparatus according to an embodiment of the present invention; Another preferred circuit diagram of the detection circuit of the signal detecting device of the embodiment of the invention; FIG. 8 is another preferred circuit diagram of the detecting circuit of the signal detecting device according to the embodiment of the present invention; and FIG. 9 is a signal detecting according to an embodiment of the present invention. A preferred structural view of the device; FIG. 10 is another preferred circuit diagram of the signal detecting device according to the embodiment of the present invention; and FIG. 11 is another embodiment between the signal detecting device and the transmitting device of the resistance value signal according to the embodiment of the present invention. An equivalent circuit diagram of a preferred connection method.

The invention will be described in detail below with reference to the drawings in conjunction with the embodiments. It should be noted that the embodiments in the present application and the features in the embodiments may be combined with each other without conflict.

An embodiment of the present invention provides a preferred signal detecting apparatus. As shown in FIG. 1, the apparatus includes a detecting circuit 110. The detecting circuit 110 includes the following connecting ends: a first end 112, a second end 114, and a third end 116. The first end 112 is connected to the power terminal 108, the second end 114 is connected between the signal receiving end 102 and the signal transmitting end 104, and the third end 116 is connected to the control end 106.

As shown in Figure 2, the power terminal 108 is used to connect a power source. As a preferred embodiment, the power source may be an on-board low-voltage DC power source, and the voltage value between the power source and the ground of the vehicle, that is, the first ground, is constant.

As shown in FIG. 2, the signal receiving end 102 is configured to receive a resistance signal. Preferably, the signal receiving end 102 can be connected to the output of the resistive sensor, and the sensor can be, but is not limited to, a built-in resistive oil pressure sensor, water temperature sensor or air temperature sensing. And so on. In the above scenario, the resistance signal is used to indicate the resistance value to be measured between the output end of the resistive sensor and the sensor ground, that is, the resistance value between the signal receiving end 102 and the second ground. There is a voltage difference between the second ground and the first ground.

As shown in FIG. 2, the signal transmitting terminal 104 is for outputting a voltage signal. Preferably, as shown in FIG. 3, the signal transmitting end 104 can be connected to an input end of the processor 180. The processor 180 can be, but is not limited to, a vehicle-mounted microprocessor or an electronic control unit, etc., and the power terminal 108. The connected power supply is common ground. In the above scenario, the voltage signal is read by the processor 180 for indicating the voltage value between the input end of the processor 180 and the ground of the processor, that is, between the signal transmitting end 104 and the first ground. Voltage value.

As shown in FIG. 2, the control terminal 106 is configured to receive a control signal. Preferably, as shown in FIG. 3, the control terminal 106 can be connected to the output end of the processor 180, that is, the processor 180 outputs the control signal. Specifically, the control terminal may be a terminal or a contact. Preferably, the above control signal may be a periodic high and low level signal or a contact on/off signal or the like. The control signal may be an active signal or a passive signal, which is not limited in the present invention.

In this embodiment, when the control signal is in the first state, the resistance between the first end 112 and the second end 114 of the detecting circuit 110 is a first resistance value, when the control signal is in the second state. The resistance between the first end 112 and the second end 114 is a second resistance value, wherein the first resistance value is not equal to the second resistance value. In the above scenario, a voltage dividing effect is formed between the power source and the second ground due to a resistance value between the first end 112 and the second end 114 of the detecting circuit 110 and an equivalent resistance formed by the resistance value to be measured. When the resistance value of the detection circuit 110 changes, and the first resistance value changes to the second resistance value, the voltage signal also changes, and the first voltage value changes to the second voltage value. The influence of the voltage difference existing between the first ground and the second ground on the resistance signal received by the signal receiving end 102 can be eliminated by the difference between the first voltage value and the second voltage value.

The principle of eliminating the influence of the ground voltage difference on the resistance signal by the difference between the first voltage value and the second voltage value will be described in detail below. In the equivalent circuit shown in FIG. 4, the power source voltage relative to the first ground, that is, the power source voltage, can be expressed as E, The second voltage difference with respect to the first ground, that is, the ground voltage difference, can be expressed as S, and the voltage signal of the signal transmitting end 104 relative to the first ground, that is, the voltage signal can be represented as V, and the detecting circuit 110 The resistance value between the one end 112 and the second end 114 can be expressed as Z, and the resistance value to be tested can be expressed as R, and the voltage value loaded across the equivalent resistance 136 of the resistance value to be tested can be expressed as U. The current value loaded on the equivalent resistor 136 can be expressed as I, and the positive direction of the voltage value U and the current value I is as shown in FIG. 4, wherein one end of the equivalent resistor 136 is connected to the second ground. The current value passed between the first end 112 and the second end 114 may be regarded as being loaded with the equivalent resistance 136 without considering the load of the circuit or device to which the signal transmitting end 104 is connected. The current values are equal.

When the control signal is in the first state, the resistance value between the first end 112 and the second end 114, that is, the first resistance value, may be represented by _{Z_on} , and the voltage value represented by the voltage signal is the first The voltage value can be represented by V _{_on} , and the voltage value loaded by the equivalent resistor 136 can be represented by U _{_on} , and the current value can be represented by I _{_on} . According to the circuit structure and circuit principle in Figure 4, it can be concluded that:

When the control signal is in the second state, the resistance value between the first end 112 and the second end 114, that is, the second resistance value, may be represented by _{Z_off} , and the voltage value indicated by the voltage signal is the first The voltage value can be represented by _{V_off} , and the voltage value loaded by the equivalent resistor 136 can be represented by _{U_off} , and the current value can be represented by _{I_off} . According to the circuit structure and circuit principle in Figure 4, it can be concluded that:

In the case where the above-mentioned resistance value to be measured is relatively stable in the above two states, the calculation formula of the resistance value to be measured can be obtained according to Ohm's law and the characteristics of the resistor as a linear element:

Therefore, according to the relationship between the voltage value and the current value loaded by the two sets of equivalent resistances, it can be obtained:

as well as

As can be seen from the above formula, in the embodiment, the difference between the first voltage value _{V_on} and the second voltage value _{V_off} can be eliminated between the first ground and the second ground. The effect of the voltage difference S on the above resistance signal.

Preferably, the processor 180 further includes an operation unit configured to determine the resistance value to be measured according to the first voltage value, the second voltage value, the power voltage, the first resistance value, and the second resistance value. Therefore, the technical effect of accurately detecting the resistance value to be tested is further realized. Further, the above test can also be performed by the display device. The measured value of the above-mentioned sensor indicated by the resistance value is displayed, and the display device may be an on-board display or a dashboard or the like. As an alternative embodiment, the display device is not shown in the drawings. It should be understood by those skilled in the art that the above-mentioned arithmetic unit is not necessary, and the above-mentioned resistance value to be measured can also be obtained by an arithmetic circuit or the like.

Specifically, as an optional implementation manner of the present invention, an accurate reading of the oil pressure signal of the vehicle can be realized by the signal detecting device described above, wherein the oil pressure signal can be output by the resistive oil pressure sensor. The end output, the oil pressure sensor can be installed separately from the other in-vehicle electronic device inside or outside the automobile or the motorcycle for detecting the oil pressure of the vehicle, and the sensor ground of the oil pressure sensor There is a systematic difference in voltage between the in-vehicle electronic control unit ECU (Electronic Control Unit). In the embodiment of the present invention, the output end of the oil pressure sensor may be connected to the signal receiving end 102 of the signal detecting device through a wire for transmitting the oil pressure signal to the signal detecting device; The signal transmitting end 104 can be connected to the input end of the processor 180 through a wire for transmitting the voltage signal output by the signal detecting device to the processor 180. The output end of the processor 180 can pass through the wire and the signal detecting device. The control terminal 106 is connected to transmit the control signal to the signal detecting device. The processor 180 may be a microprocessor (MCU), and the output signal outputted by the output terminal may be a period of 1 ms. Wave signal or pulse width modulation PWM (Pulse Width Modulation) signal. In the above scenario, the control signal may be at a high level as the first state, and the control signal may be at a low level as the second state, and the signal detecting device in the first state and the second state may be used. The resistance value between the first end 112 and the second end 114 of the detecting circuit 110, that is, the first resistance value and the second resistance value are respectively recorded as Z _{_on} and Z _{_off} , and the first state and the first state are respectively The voltage values of the voltage signals output from the signal transmitting end 104 of the signal detecting device in the two states, that is, the first voltage value and the second voltage value are respectively recorded as V _{_on} and V _{_off} , so that the following calculation formula can be accurately performed. The value of the above oil pressure signal is obtained:

Here, R is used to indicate the resistance value corresponding to the hydraulic pressure signal, and E is used to indicate the voltage value of the power supply for the ECU on the vehicle system with respect to the ECU. Further, the actual oil pressure value may be obtained according to a resistance value corresponding to the oil pressure signal and a calibration table or a calibration formula between the resistance value of the preset or calibrated oil pressure signal and the actual oil pressure value, wherein the oil is obtained. The conversion between the resistance value of the pressure signal and the actual oil pressure value can also be accomplished by the above MCU. Of course, the above is only a preferred embodiment of the present invention, and it should not be construed as limiting the invention.

Preferably, the detecting circuit 110 includes a switching circuit 120 and a first resistor 130. The switching circuit 120 and the first resistor 130 are connected to the first end 112 and the second end 114 in series or in parallel. Between, as shown in Figure 5 and Figure 6, respectively. The control input end of the switch circuit 120 is connected to the third end 116 for receiving the control signal. When the control signal is in the first state, the The switch circuit 120 is turned on, and when the control signal is in the second state, the switch circuit 120 is turned off. In the embodiment, for the case where the switch circuit 120 and the first resistor 130 are connected in series between the first end 112 and the second end 114, when the switch circuit 120 is turned on, the first end 112 and the second end 114 are The resistance value is the resistance value of the first resistor 130. When the switch circuit 120 is turned off, the first end 112 and the second end 114 are disconnected, and the resistance value can be regarded as positive infinity. For the case where the switching circuit 120 is connected in parallel with the first resistor 130 between the first end 112 and the second end 114, when the switching circuit 120 is turned on, the resistance value between the first end 112 and the second end 114 is Zero, when the switch circuit 120 is turned off, the resistance between the first end 112 and the second end 114 is the resistance of the first resistor 130.

It should be understood by those skilled in the art that the composition of the above-mentioned detection circuit 110 described in this embodiment is not unique. For example, the combination of the above-mentioned switch circuit 120 and the first resistor 130 may also be part of the detection circuit 110. The structure, or the detection circuit, may include a variable resistor controlled by an electrical signal, and the like.

Preferably, as shown in FIG. 7 and FIG. 8, the detecting circuit 110 further includes a second resistor 132 for more flexibly setting the first resistance value and the second resistance value.

As a preferred embodiment, for the case where the switch circuit 120 and the first resistor 130 are connected in series between the first end 112 and the second end 114, the second resistor 132 may be opposite to the switch circuit 120 and the first resistor. The combination of the devices 130 is connected in parallel between the first end 112 and the second end 114, as shown in FIG. Above In the scenario, when the switch circuit 120 is turned on, the resistance between the first end 112 and the second end 114 is a resistance value of the parallel circuit of the first resistor 130 and the second resistor 132, when the switch circuit When 120 is turned off, the resistance value of the second resistor 132 is between the first end 112 and the second end 114.

As another preferred embodiment, for the case where the switch circuit 120 is connected in parallel with the first resistor 130 between the first end 112 and the second end 114, the second resistor 132 may be opposite to the switch circuit 120 and the first A combination of resistors 130 is connected in series between the first end 112 and the second end 114, as shown in FIG. In the above scenario, when the switch circuit 120 is turned on, the resistance between the first end 112 and the second end 114 is the resistance value of the second resistor 132. When the switch circuit 120 is turned off, the first Between the terminal 112 and the second end 114 is a resistance value of the series circuit of the first resistor 130 and the second resistor 132.

Preferably, as shown in FIG. 9, the detecting circuit further includes one or more third resistors 134, which are connected in parallel at both ends of the first resistor 130. The third resistor 134 can be shunted in the detecting circuit 110, and on the one hand, the power sharing between the first resistor 130 and the third resistor 134 is realized, and on the other hand, the number of heat sources is increased. The efficiency of heat dissipation to solve the problem of device performance degradation and loss caused by excessive local temperature. Correspondingly, as a preferred embodiment, the signal detecting device further includes a heat dissipating mechanism 160 adjacent to the first resistor 130 and the third resistor 134 for further improving the efficiency of heat dissipation.

Preferably, the switch circuit 120 may include a MOSFET (Field Effect Transistor), the source and the drain are connected between the first end 112 and the second end 114, and the gate is connected to the above Three ends 116. Preferably, the change between the first state and the second state of the control signal is reflected in the transistor switching circuit, and can be expressed as a voltage level applied to a gate of the MOS transistor.

As a preferred embodiment, the transistor switch circuit may be a triode switch circuit. Preferably, as shown in FIG. 10, the emitter of the transistor 122 corresponds to the first end 112, the collector corresponds to the second end 114, and the base corresponds to the third end 116. In the above scenario, when the control signal received by the base of the transistor 122 through the control terminal 106 is at a high level, the transistor 122 is not turned on, and the emitter and the collector are equivalent to an off state, and vice versa. When the control signal is at a low level, the transistor 122 is turned on, and the emitter and the collector are equivalent to an on state, thereby implementing switching between the on and off states of the switch circuit 120 to further implement the first end 112. A change in resistance value between the second terminal 114 and the second end 114 described above.

Preferably, as shown in FIG. 10, the detecting circuit 110 may further include a current limiting component 140. Preferably, the current limiting component 140 can be connected between the second end 114 and the signal transmitting end 104 for limiting the current output through the signal transmitting end 104, thereby protecting the signal transmitting end 104. Circuit or device.

Preferably, as shown in FIG. 10, the detection circuit 110 may further include a pull-up resistor 142. Preferably, one of the pull-up resistors 142 The terminal may be connected between the second end 114 and the signal transmitting end 104, and the other end of the pull-up resistor 142 is connected to the power terminal 108 for turning off when the switching circuit 120 is turned off, that is, when the transistor 122 is in an off state. An additional drive is provided for the signal detecting circuit 110 to maintain the stability of the voltage signal output by the signal transmitting end 104.

In the present embodiment, in consideration of the shunting action of the pull-up resistor 142 in the circuit and the voltage division effect of the current limiting component 140, the resistance to be tested is given according to the equivalent circuit shown in FIG. A more accurate calculation of the value. In FIG. 11, the power supply voltage can be expressed as E, the ground voltage difference of the second ground relative to the first ground can be expressed as S, and the voltage signal can be represented as V, the first resistor 130 and the first resistor 130 The resistance value of the parallel circuit of the three resistors 134 can be expressed as R ₁ , the total current value through the parallel circuit can be expressed as I ₁ , and the resistance value of the pull-up resistor 142 can be expressed as R ₂ , the current limiting component 140 The resistance value can be expressed as R ₃ , and the current value of the series circuit through the pull-up resistor 142 and the current limiting component 140 can be expressed as I ₂ , and the resistance value to be tested can be expressed as R, and the equivalent resistance of the resistance value to be tested is The voltage value loaded at both ends of 136 can be expressed as U, and the current value loaded on the equivalent resistor 136 can be expressed as I, and the positive direction of the voltage value U and the current value I is as shown in FIG. One end of the equivalent resistor 136 is connected to the second ground described above. According to the circuit principle, the current value I loaded on the equivalent resistor 136 can be regarded as the current value I ₁ and the current value I ₂ without considering the load of the circuit or device to which the signal transmitting terminal 104 is connected. And value.

When the control signals are in the first state and the second state, respectively, the respective resistance values R ₁ , R ₂ , R ₃ , R, the power supply voltage E, and the ground voltage difference S may be regarded as not changing. The first voltage value can be represented by V _{_on} , and the second voltage value can be represented by V _{_off} , and each of the current values can be represented by I _{1_on} , I _{2_on} and I _{_on} in the first state, respectively, in the second state. The following can be represented by I _{1_off} , I _{2_off} and I _{_off} , respectively. The voltage value loaded above the equivalent resistor 136 can be represented by U _{_on} in the first state, and can be represented by U _{_off} in the second state. . And according to the circuit structure and circuit principle in Figure 11, it can be concluded:

as well as

among them,

Therefore, according to the relationship between the voltage value and the current value loaded by the above two sets of equivalent resistances, Ohm's law and the linear characteristics of the resistance element, it can be obtained:

as well as

As can be seen from the above formula, in the embodiment, the difference between the first voltage value _{V_on} and the second voltage value _{V_off} can be eliminated between the first ground and the second ground. The effect of the voltage difference S on the above resistance signal.

Preferably, as shown in FIG. 10, the detecting circuit 110 may further include a clamp unit circuit 150. One end of the clamp unit circuit 150 is connected between the second end 114 and the signal transmitting end 104. The other end of the circuit 150 is connected to the first ground. The other end of the clamp circuit 150 is connected to the power terminal for clamping the voltage signal within a stable voltage range. Preferably, the clamp circuit 150 may include two diodes connected in series between the first ground and the power terminal. As shown in FIG. 10, the conduction directions of the two diodes are the first Up to the power supply end, wherein, as one end of the clamp unit circuit 150, a common end between the two diodes is connected between the second end 114 and the signal transmitting end 104, thereby clamping the voltage signal The effect between the above-described power source voltage and the voltage value of the first ground described above.

Preferably, as shown in FIG. 10, the detecting circuit 110 further includes a first capacitor 144. One end of the first capacitor 144 is connected between the second end 114 and the signal transmitting end 104. The first capacitor 144 is connected. The other end is connected to the first ground for removing high frequency clutter portions, for example, sharp pulse signals, in the voltage signal.

Preferably, as shown in FIG. 10, the detecting circuit 110 may further include a second capacitor 146. One end of the second capacitor 146 is connected between the signal receiving end 102 and the second end 114. The second capacitor 146 is connected. The other end is connected to the first ground described above. Preferably, as shown in FIG. 10, the detecting circuit 110 further includes a fourth resistor 148. One end of the fourth resistor 148 is connected between the signal receiving end 102 and the second end 114. The other end of the resistor 148 is connected to the first ground described above. A parallel circuit in which one end of the second capacitor 146 and the fourth resistor 148 are grounded may attenuate electromagnetic interference doped in the resistance signal received by the signal receiving end 102.

As can be seen from the above description, the present invention achieves the following technical effects: the first ground and the second ground can be eliminated by the difference between the first voltage value _{V_on} and the second voltage value _{V_off} The influence of the voltage difference S existing between the resistance signal; and the resistance value to be measured by the first voltage value, the second voltage value, the power voltage, the first resistance value, and the second resistance value Accurate detection.

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and scope of the present invention are intended to be included within the scope of the present invention.

Claims (8)

A signal detecting device is characterized in that it comprises: a power terminal (108), a signal receiving end (102), a signal transmitting end (104), a control end (106) and a detecting circuit (110), and the detecting circuit (110) The first end (112), the second end (114) and the third end (116) are included, wherein the first end (112) is connected to the power terminal (108), and the power terminal (108) is used for connection. a power source having a constant voltage value between the power source and the first ground; the second end (114) being coupled between the signal receiving end (102) and the signal transmitting end (104), the signal receiving The terminal (102) is configured to receive a resistance signal, the resistance value is used to indicate a resistance value to be measured between the signal receiving end (102) and the second ground, and the signal transmitting end (104) is configured to send a voltage signal, the voltage signal is used to represent a voltage value between the signal transmitting end (104) and the first ground, wherein a voltage difference exists between the first ground and the second ground; The third end (116) is connected to the control end (106), the control end (106) is configured to receive a control signal, and when the control signal is in the first state, the first end (112) And a resistance value between the second end (114) is a first resistance value, and when the control signal is in the second state, between the first end (112) and the second end (114) The resistance value is a second resistance value, wherein the first resistance value is not equal to the second resistance value; wherein the signal detecting device further comprises: a processor (180), the processor (180) The input end is connected to the signal transmitting end (104), and is configured to obtain the resistance value to be tested according to the first resistance value, the second resistance value, the first voltage value, and the second voltage, wherein The first voltage value is a voltage value of the voltage signal when the control signal is in the first state, and the second voltage value is a voltage of the voltage signal when the control signal is in the second state The processor (180) is configured to obtain the resistance value to be tested according to the following formula: Wherein R is used to represent the resistance value to be tested, E is used to indicate a voltage value of the power source relative to the first ground, _{V_on is} used to represent the first voltage value, and _{V_off is} used to indicate the A second voltage value, _{Z_on is} used to represent the first resistance value, and _{Z_off is} used to represent the second resistance value. The signal detecting apparatus of claim 1, wherein an output of the processor (180) is connected to the control terminal (106) for transmitting the control signal to the control terminal (106). The signal detecting device of claim 1 or 2, wherein the detecting circuit (110) comprises: a switching circuit (120) and a first resistor (130), the switching circuit (120) and the first resistor (130) connected in series or in parallel between the first end (112) and the second end (114), wherein the control input of the switch circuit (120) and the third end (116) connected, the switch circuit (120) is turned on when the control signal is in the first state, and the switch circuit (120) is turned off when the control signal is in the second state. The signal detecting device of claim 3, wherein the detecting circuit (110) further comprises: a second resistor (132), wherein the switching circuit (120) is connected in series with the first resistor (130) When the mode is connected between the first end (112) and the second end (114), the second resistor (132) is opposite to the switch circuit (120) and the first resistor ( a combination of 130) connected in parallel between the first end (112) and the second end (114), when the switching circuit (120) is in parallel with the first resistor (130) The second resistor (132) is opposite to the switch circuit (120) and the first resistor when connected between the first end (112) and the second end (114) A combination of (130) is connected in series between the first end (112) and the second end (114). The signal detecting device of claim 3, wherein the detecting circuit (110) further comprises: one or more third resistors (134) connected in parallel across the first resistor (130). The signal detecting device of claim 5, comprising: a heat dissipating mechanism (160) adjacent to the first resistor (130) and the third resistor (134). The signal detecting device of claim 3, wherein the switching circuit (120) comprises a transistor switching circuit. The signal detecting device of claim 1 or 2, wherein the detecting circuit (110) further comprises at least one of the following: a current limiting component (140) connected between the second end (114) and the signal transmitting end (104); a pull-up resistor (142), one end of the pull-up resistor (142) is connected to the Between the second end (114) and the signal transmitting end (104), the other end of the pull-up resistor (142) is connected to the power terminal (108); the clamp circuit (150), the tong One end of the bit circuit (150) is connected between the second end (114) and the signal transmitting end (104), and the other end of the clamping bit circuit (150) is used to connect the first ground The other end of the clamp circuit (150) is connected to the power terminal (108); the first capacitor (144), one end of the first capacitor (144) is connected to the second end (114) And the signal transmitting end (104), the other end of the first capacitor (144) is used to connect the first ground; the second capacitor (146), one end of the second capacitor (146) is connected Between the signal receiving end (102) and the second end (114), the other end of the second capacitor (146) is used to connect the first ground; the fourth resistor (148), One end of the fourth resistor (148) is connected to the letter The receiving end (102) and the second end (114), the other end of said fourth resistor (148) for connecting the first ground.