High-precision workpiece table temperature measuring device

Abstract

The invention provides a high-precision workpiece table temperature measuring device, and the device comprises at least one collection circuit, and one end of each collection circuit is used for connecting a temperature sensor disposed in a to-be-measured environment, and is used for collecting a preset voltage value corresponding to the temperature sensor disposed in the to-be-measured environment; at least one signal amplification circuit, one acquisition circuit corresponds to one signal amplification circuit, and one end of each signal amplification circuit is used for being connected with the other end of the corresponding acquisition circuit so as to amplify a preset voltage value to obtain a target voltage value; the storage module is used for storing calibration data corresponding to each acquisition circuit; one end of the processing module is used for being connected with the other end of each signal amplification circuit, the other end of the processing module is used for being connected with the storage module, and the processing module is configured to perform calibration according to the target voltage value and the calibration data corresponding to each signal amplification circuit; and determining the environment temperature of the temperature sensor corresponding to each acquisition circuit.

Description

Technical Field

[0001] This application relates to the technical field of temperature detection, and particularly to a high-precision workpiece table temperature measurement device. Background Art

[0002] In the semiconductor manufacturing process, when a wafer is loaded onto a workpiece table, non-uniform temperature of the worktable can cause thermal deformation of the wafer. If there is a temperature difference between the wafer and the workpiece table, the wafer will expand or contract. However, due to the adsorption force of the workpiece table, this deformation will be restricted, thus generating stress inside the wafer. This stress not only affects the mechanical stability of the wafer, but may also cause surface defects. On the other hand, the temperature offset of the Zerodur of the workpiece table will cause its non-uniform expansion, resulting in deformation of the reflecting mirror surface, leading to positioning errors and performance losses of the interferometer; the temperature offset of the mirror will also cause changes in the refractive index of the interferometer optical path, affecting the accuracy of the interferometer measurement system, thereby affecting the positioning accuracy of the workpiece table. Therefore, it is necessary to accurately monitor the temperature change of the workpiece table so that the workpiece table can respond and adjust in time to reduce the errors caused by temperature changes.

[0003] Inside the workpiece table, the temperature is regulated by circulating cooling water in the pipeline. In order to accurately detect the temperature, NTC temperature sensors are often used. These sensors are in contact with and fixed at the measured positions to achieve stable temperature measurement. At the same time, temperature sensors are also installed at the cooling water outlet. By setting the cooling water temperature and real-time monitoring the difference between the temperature at the measured position and the temperature at the cooling water outlet, the system can accurately control the temperature at the measured position by adjusting the cooling water flow rate to ensure its stability and accuracy.

[0004] To meet the temperature control requirements of the workpiece table, the measurement accuracy of the temperature measurement circuit needs to reach 1 millikelvin (mK). It is necessary to design a dedicated detection circuit. By collecting the data of the temperature sensors at the detection positions, high-precision detected temperature is output as the signal source of the temperature control system. A common temperature detection circuit usually consists of a voltage division circuit composed of an NTC temperature sensor and a fixed resistor. The temperature change is reflected by measuring the voltage change at the voltage division point. This method will affect the measurement accuracy. The voltage division circuit of the resistor has high requirements for the stability of the power supply voltage and the accuracy of the resistor components. The fluctuations of the power supply voltage and the manufacturing tolerance of the resistor will directly affect the measurement results. And due to the temperature coefficient of the resistor, the resistance value will change with temperature, thus introducing measurement errors and reducing the measurement accuracy.

[0005] Alternatively, a current source circuit is used to allow a constant current to flow through the temperature sensor, and the temperature information is obtained by measuring the voltage across the sensor. However, a constant current flowing through the temperature sensor will cause the sensor to self-heat. Especially in high-precision measurements, a slight temperature rise will affect the measurement results and reduce the measurement accuracy. The stability of the current source circuit directly affects the measurement accuracy. Any current fluctuation will introduce errors, and the design of a high-precision current source is complex and costly. Summary of the invention

[0006] In view of this, the purpose of the present application is to at least provide a high-precision workpiece table temperature measurement device, by setting an acquisition circuit and a signal amplification circuit for each temperature sensor, and transmitting the target voltage value of the corresponding temperature sensor to the processing module through the signal amplification circuit, and the processing module retrieves the calibration data corresponding to each acquisition circuit from the storage module. Then, the processing module determines the ambient temperature of each temperature sensor through the target voltage value and calibration data output by the signal amplifier, thereby solving the technical problem of low measurement accuracy in the prior art and achieving the technical effect of improving the temperature measurement accuracy.

[0007] This application mainly includes the following aspects:

[0008] In a first aspect, an embodiment of the present application provides a high-precision workpiece table temperature measurement device, the device comprising: at least one acquisition circuit, one end of each acquisition circuit being used to connect to a temperature sensor set in a test environment, for acquiring a preset voltage value corresponding to the temperature sensor set in the test environment; at least one signal amplification circuit, one acquisition circuit corresponding to one signal amplification circuit, one end of each signal amplification circuit being used to connect to the other end of its corresponding acquisition circuit, so as to amplify the preset voltage value to obtain a target voltage value; a storage module, for storing calibration data corresponding to each acquisition circuit; a processing module, one end of the processing module being used to connect to the other end of each signal amplification circuit, and the other end of the processing module being used to connect to the storage module, wherein the processing module is configured to: determine the ambient temperature of the temperature sensor corresponding to each acquisition circuit based on the target voltage value and the calibration data corresponding to each signal amplification circuit.

[0009] Optionally, each acquisition circuit includes: a connection interface, which serves as one end of the acquisition circuit and is used to connect the two ends of the temperature sensor corresponding to the acquisition circuit; a bridge sub-circuit, which includes two bridge arms and an excitation source, and is led out from a preset resistance position of a preset bridge arm of the bridge sub-circuit as the connection interface, so as to use the temperature sensor as the preset resistance and bridge the two bridge arms of the bridge sub-circuit through the excitation source; and an acquisition interface, which serves as the other end of the acquisition circuit and is led out from the connection between the two bridge arms of the bridge sub-circuit as the acquisition interface.

[0010] Optionally, the bridge sub-circuit includes a Wheatstone bridge circuit, the Wheatstone bridge circuit includes a first constant resistor, a second constant resistor, and a third constant resistor, the connection interface includes a first connection contact and a second connection contact, and the acquisition interface includes a first acquisition contact and a second acquisition contact. Wherein, one end of the first constant resistor serves as one end of an arm of the bridge sub-circuit, the other end of the first constant resistor is connected to one end of the second constant resistor, the other end of the second constant resistor serves as the other end of an arm of the bridge sub-circuit, the first connection contact serves as one end of another arm of the bridge sub-circuit for connecting to one end of the first constant resistor, the second connection contact is connected to one end of the third constant resistor, the other end of the third constant resistor is connected to the other end of the second constant resistor, the connection point between the first connection contact and the first constant resistor serves as the first acquisition contact, and the connection point between the third constant resistor and the second constant resistor serves as the second acquisition contact.

[0011] Optionally, the excitation source includes a bandgap reference voltage source. Each acquisition circuit further includes a first power supply, a first resistor, and a second resistor. The first power supply is connected to one end of the first resistor, the other end of the first resistor is connected to one end of the bandgap reference voltage source, the other end of the bandgap reference voltage source is connected to one end of the second resistor, and the other end of the second resistor is grounded. Wherein, the connection point between the first resistor and the bandgap reference voltage source is connected to the connection point between the first constant resistor and the second constant resistor, and the connection point between the bandgap reference voltage source and the second resistor is connected to the connection point between the second connection contact and the third constant resistor to bridge between the two arms of the bridge sub-circuit through the bandgap reference voltage source.

[0012] Optionally, each acquisition circuit further includes a first capacitor, a second capacitor, a third capacitor, and a fourth capacitor. Wherein, the first capacitor and the second capacitor are connected in series between the first acquisition contact and the second acquisition contact, the connection point between the first capacitor and the second capacitor is grounded, one end of the third capacitor is connected to the first acquisition contact, the other end of the third capacitor is connected to the connection point between the second constant resistor and the third constant resistor, one end of the fourth capacitor is connected to the other end of the first capacitor, and the other end of the fourth capacitor is grounded.

[0013] Optionally, each signal amplification circuit includes: a first amplification sub-circuit, one end of the first amplification sub-circuit being one end of the signal amplification circuit; a second amplification sub-circuit, one end of the second amplification sub-circuit being connected to the other end of the first amplification sub-circuit, and the other end of the second amplification sub-circuit being the other end of the signal amplification circuit.

[0014] Optionally, the acquisition interface includes a first acquisition contact and a second acquisition contact. The first amplification sub-circuit includes a first operational amplifier, a second operational amplifier, a third resistor, a fourth resistor, and a fifth resistor. Among them, the first input terminal of the first operational amplifier is connected to the first acquisition contact, the second input terminal of the first operational amplifier is connected to one end of the third resistor, the first input terminal of the second operational amplifier is connected to the second acquisition contact, the second input terminal of the second operational amplifier is connected to one end of the fourth resistor, the fifth resistor is disposed between the second input terminal of the first operational amplifier and the second input terminal of the second operational amplifier, the output terminal of the first operational amplifier is connected to the other end of the third resistor, and the output terminal of the second operational amplifier is connected to the other end of the fourth resistor, serving as the other end of the first amplification sub-circuit.

[0015] Optionally, the second amplification sub-circuit includes an instrumentation amplifier, a sixth resistor, a seventh resistor, and a fifth capacitor. The input terminal of the instrumentation amplifier is one end of the second amplification sub-circuit. The power supply terminal of the instrumentation amplifier is connected to a second power supply. One end of the sixth resistor is connected to the first pin of the instrumentation amplifier, the other end of the sixth resistor is connected to the second pin of the instrumentation amplifier, the output terminal of the instrumentation amplifier is connected to one end of the seventh resistor, the other end of the seventh resistor is the other end of the second amplification sub-circuit, one end of the fifth capacitor is connected to the other end of the seventh resistor, and the other end of the fifth capacitor is grounded.

[0016] Optionally, the processing module includes an analog-to-digital converter and a processor. Among them, the analog-to-digital converter includes a plurality of acquisition pins, one acquisition pin corresponding to one signal amplification circuit. Each acquisition pin of the analog-to-digital converter is connected to the other end of its corresponding signal amplification circuit. The output terminal of the analog-to-digital converter is connected to the first input terminal of the processor. The second input terminal of the processor is connected to the storage module. The analog-to-digital converter is configured to convert the voltage analog signal of the target voltage value corresponding to each acquisition pin into a voltage digital signal and transmit the voltage digital signal to the processor. The processor is configured to determine the ambient temperature of the temperature sensor corresponding to the acquisition circuit according to the voltage digital signal corresponding to each acquisition pin and the calibration data.

[0017] Optionally, the device further includes a communication module and a host computer. The output end of the processor is connected to the input end of the communication module, and the output end of the communication module is connected to the host computer, so as to transmit the ambient temperature where the temperature sensor corresponding to each acquisition circuit is located to the host computer through the communication module.

[0018] A high-precision workpiece table temperature measurement device provided by an embodiment of the present application, the device includes: at least one acquisition circuit, one end of each acquisition circuit is used to connect a temperature sensor arranged in a to-be-measured environment, and is used to acquire a preset voltage value corresponding to the temperature sensor arranged in the to-be-measured environment; at least one signal amplification circuit, one acquisition circuit corresponds to one signal amplification circuit, and one end of each signal amplification circuit is used to connect the other end of its corresponding acquisition circuit to perform amplification processing on the preset voltage value to obtain a target voltage value; a storage module, which is used to store calibration data corresponding to each acquisition circuit; a processing module, one end of the processing module is used to connect the other end of each signal amplification circuit, and the other end of the processing module is used to connect the storage module, wherein the processing module is configured to: determine the ambient temperature where the temperature sensor corresponding to each acquisition circuit is located according to the target voltage value corresponding to each signal amplification circuit and the calibration data. By correspondingly arranging an acquisition circuit and a signal amplification circuit for each temperature sensor, and transmitting the target voltage value of its corresponding temperature sensor to the processing module through the signal amplification circuit, and the processing module retrieves the calibration data corresponding to each acquisition circuit from the storage module, and further, the processing module determines the ambient temperature where each temperature sensor is located through the target voltage value output by the signal amplifier and the calibration data, which solves the technical problem of low measurement accuracy in the prior art and achieves the technical effect of improving the temperature measurement accuracy.

[0019] In order to make the above objects, features and advantages of the present application more obvious and understandable, the following specifically enumerates preferred embodiments and cooperates with the attached drawings to make a detailed description as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0021] Figure 1 The structural schematic diagram of a high-precision workpiece table temperature measurement device provided by an embodiment of the present application is shown.

[0022] Figure 2The circuit diagram of a collection circuit provided by an embodiment of the present application is shown.

[0023] Figure 3 The circuit diagram of another collection circuit provided by an embodiment of the present application is shown.

[0024] Figure 4 The circuit diagram of the signal amplification circuit provided by an embodiment of the present application is shown.

[0025] Figure 5 The structural schematic diagram of another high-precision workpiece table temperature measurement device provided by an embodiment of the present application is shown. Detailed implementation manners

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. It should be understood that the accompanying drawings in the present application are only for the purposes of illustration and description, and are not used to limit the protection scope of the present application. In addition, it should be understood that the schematic drawings are not drawn according to the actual scale. The flowcharts used in the present application show the operations implemented according to some embodiments of the present application. It should be understood that the operations in the flowcharts may not be implemented in sequence, and the steps without logical context relationships may be reversed or implemented simultaneously. In addition, those skilled in the art may add one or more other operations to the flowchart or remove one or more operations from the flowchart under the guidance of the content of the present application.

[0027] In addition, the described embodiments are only some embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application usually described and shown in the accompanying drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application to be protected, but only represents the selected embodiments of the present application. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative efforts belong to the protection scope of the present application.

[0028] In the prior art, the temperature change data is usually collected by the resistor voltage division method, that is, a temperature sensor and a fixed resistor are used to form a voltage division circuit, and the voltage change at the voltage division point is measured to reflect the temperature change. This method has the following problems: ① Limited measurement accuracy: The resistor voltage division circuit has high requirements for the stability of the power supply voltage and the accuracy of the resistor elements. The fluctuations of the power supply voltage and the manufacturing tolerance of the resistor will directly affect the measurement result, resulting in a decrease in the measurement accuracy. ② Great influence of temperature drift: The temperature coefficient of the resistor will cause the resistance value to change with temperature, thereby introducing measurement errors and making it difficult to meet the requirements of high-precision temperature measurement.

[0029] Another commonly used temperature measurement circuit utilizes a current source circuit. A constant current is made to flow through the temperature sensor, and the temperature information is obtained by measuring the voltage across the sensor. However, this method also has drawbacks: ① The self-heating effect is obvious: The constant current flowing through the temperature sensor causes self-heating of the sensor. Especially in high-precision measurements, even a tiny temperature rise will affect the measurement result and reduce the measurement accuracy. ② High requirements for the stability of the current source: The stability of the current source circuit directly affects the measurement accuracy. Any current fluctuation will introduce errors, and the design of a high-precision current source is complex and costly.

[0030] Based on this, the embodiments of the present application provide a high-precision workpiece table temperature measurement device. By correspondingly setting an acquisition circuit and a signal amplification circuit for each temperature sensor, and transmitting the target voltage value of its corresponding temperature sensor to the processing module through the signal amplification circuit, and the processing module retrieves the calibration data corresponding to each acquisition circuit from the storage module. Furthermore, the processing module determines the ambient temperature of each temperature sensor based on the target voltage value output by the signal amplifier and the calibration data, solving the technical problem of low measurement accuracy in the prior art and achieving the technical effect of improving the temperature measurement accuracy, as follows:

[0031] Please refer to Figure 1 , Figure 1 which is a schematic structural diagram of a high-precision workpiece table temperature measurement device provided by the embodiments of the present application. As Figure 1 shown, the high-precision workpiece table temperature measurement device provided by the embodiments of the present application includes: at least one acquisition circuit 101, one end of each acquisition circuit is used to connect a temperature sensor arranged in the environment to be measured, for acquiring the preset voltage value corresponding to the temperature sensor arranged in the environment to be measured; at least one signal amplification circuit 102, one acquisition circuit corresponds to one signal amplification circuit, one end of each signal amplification circuit is used to connect the other end of its corresponding acquisition circuit to amplify the preset voltage value to obtain a target voltage value; a storage module 103, for storing the calibration data corresponding to each acquisition circuit; a processing module 104, one end of the processing module is used to connect the other end of each signal amplification circuit, and the other end of the processing module is used to connect the storage module, wherein the processing module is configured to: determine the ambient temperature of the temperature sensor corresponding to each acquisition circuit based on the target voltage value corresponding to each signal amplification circuit and the calibration data.

[0032] That is to say, at least one temperature sensor is arranged in the environment to be measured. The environment to be measured can be inside the workpiece table for placing wafers mentioned in the background art, or an environment that requires high-precision temperature detection. For each temperature sensor, the temperature sensor corresponds to an acquisition circuit and a signal amplification circuit. The acquisition circuit acquires the preset temperature value corresponding to the temperature sensor, and the preset temperature value is amplified by the signal amplification circuit to obtain the target temperature value, and then the target temperature value is transmitted to the processing module. One end of the processing module includes a plurality of acquisition pins. One acquisition pin is correspondingly connected to one signal amplification circuit. One acquisition pin receives the target voltage value sent by the signal amplification circuit to which it is correspondingly connected, so that the processing module calls out the calibration data of the temperature sensor corresponding to the pin in the entire loop from the storage module according to the pin receiving the target temperature value, and determines the ambient temperature where the temperature sensor is located through the target temperature value and the calibration data, so as to know the ambient temperature where each temperature sensor is located.

[0033] Among them, the calibration data corresponding to each temperature sensor is determined in the following manner: each acquisition pin of the processing module is fixedly connected to its corresponding signal amplification circuit and acquisition circuit, and the ambient temperature where the temperature sensor is located is set as the preset temperature value. Furthermore, the test temperature value where it is located is calculated through the target temperature value received by each acquisition pin of the processing module, and the calibration data of each sampling pin is determined through the test temperature value and the preset temperature value corresponding to each sampling pin, so as to obtain the calibration data corresponding to each temperature sensor.

[0034] Furthermore, the calibration data of each branch where the acquisition pin is located is stored through the storage module to eliminate the technical problem that the inaccuracy of the target voltage value caused by the manufacturing tolerances of the sampling circuit, the signal amplification circuit and the processing module leads to the inaccuracy of the subsequently calculated ambient temperature. That is to say, the manufacturing tolerances of the various electronic components on the sampling circuit will cause an inherent offset voltage error. The wire resistance and the interaction between the input offset current or the input signals caused by the different target voltage values input by the various acquisition pins of the processing module may all cause a small offset voltage, which affects the accuracy of temperature measurement. By storing the calibration data in the storage module, the data collected by each channel can be automatically error-corrected, ensuring high-precision temperature measurement and effectively improving the stability and reliability of the entire acquisition system.

[0035] Please refer to Figure 2 , Figure 2 which is the circuit diagram of an acquisition circuit provided by an embodiment of the present application. As Figure 2As shown in the figure, the acquisition circuit 101 provided by the embodiment of the present application includes: a connection interface (NTC_P and NTC_N), which is one end of the acquisition circuit and is used to connect both ends of the corresponding temperature sensor of the acquisition circuit; a bridge sub-circuit 1011, which includes two bridge arms and an excitation source. The connection interface is led out from a preset resistance position of a preset bridge arm of the bridge sub-circuit to use the temperature sensor as the preset resistance, and the excitation source is used to bridge between the two bridge arms of the bridge sub-circuit; an acquisition interface (V P and V N ), which is the other end of the acquisition circuit and is led out from the connection point between the two bridge arms of the bridge sub-circuit as the acquisition interface.

[0036] Wherein, for each acquisition circuit, the connection interface of the acquisition circuit is used to connect both ends of its corresponding temperature sensor, and the temperature sensor is used as a preset resistance on one bridge arm of the bridge sub-circuit through the connection interface, so that the bridge sub-circuit of the acquisition circuit can collect the initial voltage value at both ends of the temperature sensor. Furthermore, through the bridge sub-circuit of the acquisition circuit, it can be reflected that when the ambient temperature where the temperature sensor is located changes, the voltage at both ends of the connection interface changes, and the preset voltage value output by the acquisition interface also changes.

[0037] The bridge sub-circuit includes a Wheatstone bridge circuit. The Wheatstone bridge circuit includes a first constant resistor R ref1 , a second constant resistor R ref2 , a third constant resistor R ref3 . The connection interface includes a first connection contact NTC_P and a second connection contact NTC_N. The acquisition interface includes a first acquisition contact V P and a second acquisition contact V N . Among them, one end of the first constant resistor is one end of a bridge arm of the bridge sub-circuit, the other end of the first constant resistor is connected to one end of the second constant resistor, the other end of the second constant resistor is the other end of a bridge arm of the bridge sub-circuit, the first connection contact is one end of another bridge arm of the bridge sub-circuit for connecting one end of the first constant resistor, the second connection contact is connected to one end of the third constant resistor, the other end of the third constant resistor is connected to the other end of the second constant resistor, the connection point between the first connection contact and the first constant resistor is used as the first acquisition contact, and the connection point between the third constant resistor and the second constant resistor is used as the second acquisition contact.

[0038] The excitation source includes a bandgap reference voltage source AD1580, and each acquisition circuit also includes a first power supply (+5VD), a first resistor R1 and a second resistor R2, the first power supply is connected to one end of the first resistor, the other end of the first resistor is connected to one end of the bandgap reference voltage source, the other end of the bandgap reference voltage source is connected to one end of the second resistor, and the other end of the second resistor is grounded, wherein the connection between the first resistor and the bandgap reference voltage source is connected to the connection between the first constant resistor and the second constant resistor, and the connection between the bandgap reference voltage source and the second resistor is connected to the connection between the second connection contact and the third constant resistor, so as to bridge the two bridge arms of the bridge sub-circuit through the bandgap reference voltage source.

[0039] That is, one arm of the bridge sub-circuit includes a first constant resistor R ref1 and the second constant resistor R ref2 The other arm of the bridge sub-circuit includes a temperature sensor connected to the connection interface and a third constant resistor R ref3 The first resistor and the second resistor are current limiting resistors.

[0040] Exemplarily, when the environment to be tested is inside the workbench where the wafer is placed, when the temperature of the workbench changes, the resistance value of the temperature sensor will change with the temperature, affecting the bridge balance of the bridge sub-circuit. Since the standard operating temperature of the workbench is 22 degrees Celsius, the reference temperature is set to 22 degrees Celsius, that is, when the temperature of the workbench is 22 degrees Celsius, the bridge sub-bridge should be in a bridge balance state, and the resistance value of each constant resistor on the bridge sub-circuit should be equal to the corresponding resistance value of the temperature sensor in the workbench at 22 degrees Celsius. At this time, the preset voltage value output by the bridge sub-bridge is 0.

[0041] Exemplarily, since the internal temperature range of the workpiece table is 20 degrees Celsius to 24 degrees Celsius, the temperature sensor adopts a 10K3A1B model NTC temperature sensor, and the resistance of the temperature sensor is 12493 ohms at 20 degrees Celsius, and the resistance of the temperature sensor is 10450 ohms at 24 degrees Celsius. Each constant resistor on the bridge subcircuit selects a metal foil resistor of the MP11K2L model as a Wheatstone bridge arm resistor, with a resistance accuracy of 0.05% and a maximum resistance temperature coefficient of 5ppm / °C, which can greatly avoid the inherent offset voltage caused by the nominal resistance difference caused by the manufacturer's manufacturing tolerance. Among them, the constant resistor can use any other type of high-precision, low-temperature drift resistor, such as precision metal film resistors, thin film resistors, etc., as long as it has sufficient accuracy and temperature stability, and this application does not limit the model of the constant resistor.

[0042] Exemplarily, the AD1580 bandgap reference voltage source can be adopted as the excitation source to provide a stable voltage value. This voltage source has precise matching and thermal tracking characteristics, and can provide excellent accuracy and stability, thus ensuring the performance of the temperature measurement circuit. In addition, the low-voltage characteristic of the AD1580 further reduces the self-heating effect of the temperature sensor caused by the excitation voltage, thereby minimizing the temperature error. Besides adopting the AD1580 bandgap reference voltage source, other voltage reference chips with high stability and low power consumption, such as ADR4525, LT6655, etc., can also be used. These chips also have the characteristics of low temperature drift and high precision, and can be used to provide a stable excitation voltage. Or, the excitation source can adopt a constant current source mode, using a high-precision and low-temperature-drift constant current source current, for example, using constant current source modes such as REF200, LT3092, etc., to provide current excitation for the bridge.

[0043] Among them, the self-heating power of the temperature sensor is calculated by the following formula:

[0044]

[0045] In formula (1), P NTC,MAX refers to the maximum self-heating power of the temperature sensor; U bridge refers to the bridging voltage provided by the excitation source, that is, the reference voltage of the AD1580 bandgap reference voltage source; R NTC,MAX refers to the maximum resistance value of the temperature sensor, R ref1 refers to the resistance value of the first constant resistor. Furthermore, by using the AD1580 bandgap reference voltage source to provide a low excitation voltage (1.225V), the electric energy flowing through the temperature sensor is reduced. After calculation, the maximum self-heating power is only 33 μW. Furthermore, compared with the traditional current source mode, the self-heating effect of the temperature sensor is effectively reduced, and the measurement error caused by the self-heating of the temperature sensor is avoided.

[0046] Furthermore, when the temperature of the workpiece table changes, the balance of the bridge sub-circuit is broken, and the preset voltage value output by the acquisition interface is calculated by the following formula:

[0047]

[0048] In formula (2), V D refers to the preset voltage value output by the acquisition interface; V P refers to the voltage of the first acquisition contact; V N refers to the voltage of the second acquisition contact; U bridge refers to the bridging voltage provided by the excitation source, that is, the reference voltage of the AD1580 bandgap reference voltage source; R NTC refers to the resistance value of the temperature sensor; R ref1refers to the resistance value of the first constant resistor; R ref2 refers to the resistance value of the second constant resistor; R ref3 refers to the resistance value of the third constant resistor. Further, when the preset voltage value output by the acquisition interface is acquired, the resistance value R of the temperature sensor can be calculated according to formula (2) NTC , and in combination with the conversion relationship between the preset temperature and resistance of the temperature sensor, the initial temperature where the temperature sensor is located is determined, and then the initial temperature is calibrated according to the calibration data corresponding to the acquisition pin of the processing module connected to the temperature sensor, so as to determine the accurate ambient temperature where the temperature sensor is located.

[0049] Please refer to Figure 3 , Figure 3 which is the circuit diagram of another acquisition circuit provided by the embodiment of the present application. As Figure 3 shown, each acquisition circuit provided by the embodiment of the present application further includes a first capacitor C1, a second capacitor C2, a third capacitor C3 and a fourth capacitor C4. Among them, the first capacitor and the second capacitor are connected in series between the first acquisition contact and the second acquisition contact, and the connection point between the first capacitor and the second capacitor is grounded. One end of the third capacitor is connected to the first acquisition contact, and the other end of the third capacitor is connected to the connection point between the second constant resistor and the third constant resistor. One end of the fourth capacitor is connected to the other end of the first capacitor, and the other end of the fourth capacitor is grounded.

[0050] Among them, the first capacitor C1 and the second capacitor C2 are differential filtering capacitors, the third capacitor C3 is a common-mode filtering capacitor, and the fourth capacitor C4 is a decoupling resistor. That is to say, by setting an electromagnetic interference filter (RFI filter) on the acquisition circuit, it is possible to prevent the signal amplification circuit connected to the acquisition circuit from rectifying the interference signal to generate an offset error. This filter can effectively suppress high-frequency noise and electromagnetic interference, and ensure the purity of the measurement signal. The differential bandwidth is calculated by the following formula:

[0051]

[0052] In formula (2), BW diff refers to the differential bandwidth of the temperature sensor input filter connected to the connection interface; R NTC refers to the resistance value of the temperature sensor; R ref1 refers to the resistance value of the first constant resistor; R ref2 refers to the resistance value of the second constant resistor; R ref3 refers to the resistance value of the third constant resistor; C1 refers to the capacitance value of the first capacitor; C2 refers to the capacitance value of the second capacitor; C3 refers to the capacitance value of the third capacitor; C4 refers to the capacitance value of the fourth capacitor; BW PRefers to the differential bandwidth of the input filter connected to the interface NTC_P; BW N Refers to the differential bandwidth of the input filter connected to the interface NTC_N. That is, Equation (3) is calculated by substituting the equivalent resistance and equivalent capacitance into the bandwidth calculation formula for differential signals. Furthermore, by reasonably selecting the component parameters of the filter, high-frequency noise can be effectively filtered while maintaining the required signal bandwidth to ensure the accurate transmission of voltage signals. In addition to using RFI filters, low-pass filters, band-pass filters, or common-mode chokes can also be designed to suppress interference at various frequencies to ensure the purity of voltage signals.

[0053] Please refer to Figure 4 , Figure 4 which is the circuit diagram of the signal amplification circuit provided by the embodiment of the present application. As Figure 4 shown, each signal amplification circuit provided by the embodiment of the present application includes: a first amplification sub-circuit 1021, one end of the first amplification sub-circuit serves as one end of the signal amplification circuit; a second amplification sub-circuit 1022, one end of the second amplification sub-circuit is connected to the other end of the first amplification sub-circuit, and the other end of the second amplification sub-circuit serves as the other end of the signal amplification circuit.

[0054] As Figure 4 shown, the acquisition interface includes a first acquisition contact V P and a second acquisition contact V N , the first amplification sub-circuit 1021 includes a first operational amplifier AD1, a second operational amplifier AD2, a third resistor R3, a fourth resistor R4, and a fifth resistor R5. The first input terminal of the first operational amplifier is connected to the first acquisition contact, the second input terminal of the first operational amplifier is connected to one end of the third resistor, the first input terminal of the second operational amplifier is connected to the second acquisition contact, the second input terminal of the second operational amplifier is connected to one end of the fourth resistor, the fifth resistor is disposed between the second input terminal of the first operational amplifier and the second input terminal of the second operational amplifier, the output terminal of the first operational amplifier is connected to the other end of the third resistor, and the output terminal of the second operational amplifier is connected to the other end of the fourth resistor, serving as the other end of the first amplification sub-circuit.

[0055] Wherein, the second amplification sub-circuit 1022 includes an instrumentation amplifier AD3, a sixth resistor R6, a seventh resistor R7, and a fifth capacitor C5. The input terminal of the instrumentation amplifier serves as one end of the second amplification sub-circuit. The power supply terminal of the instrumentation amplifier is connected to a second power supply. One end of the sixth resistor is connected to the first pin of the instrumentation amplifier, and the other end of the sixth resistor is connected to the second pin of the instrumentation amplifier. The output terminal of the instrumentation amplifier is connected to one end of the seventh resistor, and the other end of the seventh resistor serves as the other end of the second amplification sub-circuit. One end of the fifth capacitor is connected to the other end of the seventh resistor, and the other end of the fifth capacitor is grounded.

[0056] Wherein, since the preset voltage value output by the bridge sub-circuit is in the millivolt level, high-gain and low-noise signal amplification is required to facilitate the processing module to process the amplified target voltage value. Exemplarily, the first operational amplifier and the second operational amplifier can select AD8629, and the instrumentation amplifier can select AD8226, so as to form a buffer-instrumentation amplification structure to amplify the voltage signal corresponding to the preset voltage value. AD8629 is a precision operational amplifier with ultra-low input bias current and low noise, which is very suitable for high-impedance and weak signals. AD8226 is an instrumentation amplifier with high common-mode rejection ratio and low input noise, which can effectively suppress noise and provide accurate differential signal amplification. The signal amplification circuit amplifies the weak preset voltage value output by the bridge into a target voltage value, so that the target voltage value is within the input voltage range required by the processing module. At the same time, it buffers the high-impedance bridge, improves the measurement accuracy, and provides sufficient driving ability for the processing module.

[0057] Exemplarily, the sixth resistor of the present application is used as a gain setting resistor. By changing the resistance value of the sixth resistor, the gain of the AD8226 chip can be changed, that is, by adjusting the resistance value of the sixth resistor, it can be controlled how many times the input voltage of AD8226 is amplified, and the gain range can be controlled between 1 and 1000.

[0058] Since the signal output by the bridge is weak and has high-impedance characteristics, directly connecting to the processing module will cause signal attenuation and errors. Furthermore, by adopting a buffer-instrumentation amplifier structure to amplify and buffer the signal, this design avoids the load effect caused by directly driving the processing module by the high-impedance bridge, maintains the integrity of the signal, improves the measurement accuracy. At the same time, the high common-mode rejection ratio and low-noise characteristics of the amplifier enhance the anti-interference ability of the system. Exemplarily, other operational amplifiers or instrumentation amplifiers with low noise and high common-mode rejection ratio can also be selected, such as OPA227, INA333, LT1013, etc.; or, devices with signal amplification functions are adopted, including operational amplifiers, instrumentation amplifiers, differential amplifiers, or through different combinations, to achieve precise amplification and buffering of the signal output by the bridge.

[0059] Please refer to Figure 5 , Figure 5 which is a schematic structural diagram of another high-precision workpiece table temperature measurement device provided by an embodiment of the present application. As Figure 5 shown, the processing module provided by the embodiment of the present application includes an analog-to-digital converter ADC and a processor MCU. Among them, the analog-to-digital converter includes a plurality of acquisition pins (AIN0 to AIN11), and one acquisition pin corresponds to one signal amplification circuit. The other end of each acquisition pin of the analog-to-digital converter is connected to its corresponding signal amplification circuit. The output end of the analog-to-digital converter is connected to the first input end of the processor, and the second input end of the processor is connected to the storage module 103. The analog-to-digital converter is used to convert the voltage analog signal of the target voltage value corresponding to each acquisition pin into a voltage digital signal and transmit the voltage digital signal to the processor. The processor is used to determine the ambient temperature where the temperature sensor corresponding to the acquisition circuit is located according to the voltage digital signal corresponding to each acquisition pin and the calibration data.

[0060] As Figure 5 shown, the device further includes a communication module and a host computer. Among them, the output end of the processor is connected to the input end of the communication module, and the output end of the communication module is connected to the host computer to transmit the ambient temperature where the temperature sensor corresponding to each acquisition circuit is located to the host computer through the communication module.

[0061] That is to say, the processing module in the present application includes an analog-to-digital converter ADC and a processor MCU. The model of the analog-to-digital converter ADC is selected as TLV2556, which includes 11 acquisition pins and 11 channels for simultaneous acquisition and processing, with high integration, low power consumption and stronger functions. Each acquisition pin is connected to a corresponding signal amplification circuit to receive the voltage analog signal of the target voltage value. The analog-to-digital converter converts the voltage analog signal received by each acquisition pin into a voltage digital signal and sends the voltage digital signal to the processor MCU. The analog-to-digital converter ADC can use other high-precision and low-noise analog-to-digital converters, such as AD7799, ADS1248, MAX11270. The processor MCU filters and linearizes the received voltage digital signal, and combines the calibration data stored in the storage module to calibrate each channel corresponding to each acquisition pin to calculate the ambient temperature where each temperature sensor is located and eliminate the influence of system internal errors.

[0062] Moreover, the processor MCU uploads the calculated ambient temperature to the host computer through the communication module, realizing real-time monitoring and precise control of the temperature of the workpiece table. Among them, the storage module can be selected from FLASH memory, EEPROM, FRAM, or external memory, etc. Considering the errors that may be introduced by the manufacturing tolerances of each circuit, ADC offset, gain error, etc., the errors of each channel are eliminated for calibration, and the inherent errors in the system are eliminated through calibration data, improving the consistency and accuracy of multi-channel measurement and ensuring high-precision temperature measurement.

[0063] Furthermore, the present application has excellent anti-misoperation ability. When the first connection contact NTC_P of the connection interface is accidentally short-circuited to the ground, or when the first connection contact NTC_P is connected to the second connection contact NTC_N terminal, the circuit will not be damaged at all. This characteristic ensures that the system can still maintain a stable and reliable working state during installation, maintenance, or operation, even if miswiring or sensor failure occurs, greatly improving the safety and reliability of the system.

[0064] Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working processes of the systems and devices described above can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated herein. In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division, and there can be other division methods in actual implementation. For another example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some communication interfaces, and the indirect couplings or communication connections of the devices or units can be in electrical, mechanical, or other forms.

[0065] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0066] In addition, in each embodiment of the present application, the functional units can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit.

[0067] When the above-mentioned function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a non-volatile computer-readable storage medium executable by a processor. Based on such an understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical discs that can store program codes.

[0068] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should all be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A high-precision workpiece table temperature measurement device, characterized in that: The device comprises: At least one acquisition circuit, one end of each acquisition circuit is used to connect to a temperature sensor set in the test environment, and is used to acquire a preset voltage value corresponding to the temperature sensor set in the test environment; At least one signal amplifying circuit, one acquisition circuit corresponds to one signal amplifying circuit, one end of each signal amplifying circuit is used to connect to the other end of its corresponding acquisition circuit, so as to amplify the preset voltage value to obtain a target voltage value; A storage module, used for storing calibration data corresponding to each acquisition circuit; a processing module, one end of which is used to connect to the other end of each signal amplifying circuit, and the other end of which is used to connect to the storage module. Wherein, the processing module is configured to determine the ambient temperature of the temperature sensor corresponding to each acquisition circuit according to the target voltage value corresponding to each signal amplification circuit and the calibration data.

2. The device according to claim 1, characterized in that Each acquisition circuit includes: A connection interface, as one end of the acquisition circuit, is used to connect two ends of the temperature sensor corresponding to the acquisition circuit; A bridge subcircuit, comprising two bridge arms and an excitation source, wherein a preset resistance position of a preset bridge arm of the bridge subcircuit is led out as the connection interface, so that the temperature sensor is used as the preset resistance, and the two bridge arms of the bridge subcircuit are bridged by the excitation source; The acquisition interface, as the other end of the acquisition circuit, is led out from the connection between the two bridge arms of the bridge sub-circuit as the acquisition interface.

3. The device according to claim 2, characterized in that The bridge subcircuit includes a Wheatstone bridge circuit, the Wheatstone bridge circuit includes a first constant resistor, a second constant resistor, and a third constant resistor, the connection interface includes a first connection contact and a second connection contact, and the collection interface includes a first collection contact and a second collection contact, wherein one end of the first constant resistor serves as one end of a bridge arm of the bridge sub-circuit, the other end of the first constant resistor is connected to one end of the second constant resistor, the other end of the second constant resistor serves as the other end of a bridge arm of the bridge sub-circuit, the first connecting contact serves as one end of another bridge arm of the bridge sub-circuit for connecting one end of the first constant resistor, the second connecting contact is connected to one end of the third constant resistor, and the other end of the third constant resistor is connected to the other end of the second constant resistor, The connection point between the first connection contact and the first constant resistor serves as the first collection contact point, and the connection point between the third constant resistor and the second constant resistor serves as the second collection contact point.

4. The device according to claim 3, characterized in that The excitation source includes a bandgap reference voltage source, and each acquisition circuit also includes a first power supply, a first resistor and a second resistor. The first power supply is connected to one end of the first resistor, the other end of the first resistor is connected to one end of the bandgap reference voltage source, the other end of the bandgap reference voltage source is connected to one end of the second resistor, and the other end of the second resistor is grounded. Among them, the connection between the first resistor and the bandgap reference voltage source is connected to the connection between the first constant resistor and the second constant resistor, and the connection between the bandgap reference voltage source and the second resistor is connected to the connection between the second connection contact and the third constant resistor, so as to bridge the two bridge arms of the bridge sub-circuit through the bandgap reference voltage source.

5. The device according to claim 4, characterized in that Each acquisition circuit also includes a first capacitor, a second capacitor, a third capacitor and a fourth capacitor. The first capacitor and the second capacitor are connected in series between the first collection contact and the second collection contact, the connection between the first capacitor and the second capacitor is grounded, one end of the third capacitor is connected to the first collection contact, the other end of the third capacitor is connected to the connection between the second constant resistor and the third constant resistor, one end of the fourth capacitor is connected to the other end of the first capacitor, and the other end of the fourth capacitor is grounded.

6. The device according to claim 1, characterized in that Each signal amplification circuit includes: A first amplifying sub-circuit, wherein one end of the first amplifying sub-circuit serves as one end of the signal amplifying circuit; A second amplifying sub-circuit, one end of the second amplifying sub-circuit is connected to the other end of the first amplifying sub-circuit, and the other end of the second amplifying sub-circuit serves as the other end of the signal amplifying circuit.

7. The device according to claim 6, characterized in that The acquisition interface includes a first acquisition contact and a second acquisition contact, the first amplification subcircuit includes a first operational amplifier, a second operational amplifier, a third resistor, a fourth resistor and a fifth resistor, The first input end of the first operational amplifier is connected to the first collection contact, the second input end of the first operational amplifier is connected to one end of the third resistor, the first input end of the second operational amplifier is connected to the second collection contact, the second input end of the second operational amplifier is connected to one end of the fourth resistor, and the fifth resistor is arranged between the second input end of the first operational amplifier and the second input end of the second operational amplifier. The output end of the first operational amplifier is connected to the other end of the third resistor, and the output end of the second operational amplifier is connected to the other end of the fourth resistor, serving as the other end of the first amplifying sub-circuit.

8. The device according to claim 6, characterized in that The second amplification sub-circuit includes an instrumentation amplifier, a sixth resistor, a seventh resistor and a fifth capacitor. The input end of the instrumentation amplifier serves as one end of the second amplification sub-circuit, the power supply end of the instrumentation amplifier is connected to the second power supply, one end of the sixth resistor is connected to the first pin of the instrumentation amplifier, the other end of the sixth resistor is connected to the second pin of the instrumentation amplifier, the output end of the instrumentation amplifier is connected to one end of the seventh resistor, the other end of the seventh resistor serves as the other end of the second amplification sub-circuit, one end of the fifth capacitor is connected to the other end of the seventh resistor, and the other end of the fifth capacitor is grounded.

9. The device according to claim 1, characterized in that The processing module includes an analog-to-digital converter and a processor. The analog-to-digital converter includes a plurality of acquisition pins, one acquisition pin corresponds to a signal amplification circuit, each acquisition pin of the analog-to-digital converter is connected to the other end of a corresponding signal amplification circuit, the output end of the analog-to-digital converter is connected to the first input end of the processor, and the second input end of the processor is connected to the storage module. The analog-to-digital converter is used to convert the voltage analog signal of the target voltage value corresponding to each acquisition pin into a voltage digital signal, and transmit the voltage digital signal to the processor, The processor is used to determine the ambient temperature of the temperature sensor corresponding to the acquisition circuit according to the voltage digital signal corresponding to each acquisition pin and the calibration data.

10. The device according to claim 8, characterized in that The device also includes a communication module and a host computer. Among them, the output end of the processor is connected to the input end of the communication module, and the output end of the communication module is connected to the host computer, so that the ambient temperature of the temperature sensor corresponding to each acquisition circuit is transmitted to the host computer through the communication module.

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