Position detection circuit and position detection system

Abstract

The invention provides a position detection circuit and a position detection system. The position detection circuit comprises a position sensitive detector, a current-voltage conversion circuit and a differential conversion circuit, the current and voltage conversion circuit is electrically connected with the position sensitive detector and the differential conversion circuit respectively; the conversion differential circuit is also connected with the signal acquisition circuit through a twisted pair; wherein the position sensitive detector is used for converting a light spot position into a current signal of each electrode; the current-voltage conversion circuit is used for acquiring current signals from each electrode of the position sensitive detector, converting the current signals of each electrode into voltage signals and transmitting the voltage signals to the differential conversion circuit; and the to-differential circuit is used for converting each voltage signal output by the current-voltage conversion circuit into a differential signal and transmitting the differential signal to the signal acquisition circuit through a twisted pair. Therefore, the signal stability and the transmission distance are improved by performing current-voltage conversion and differential signal transmission on the signal acquired by the position sensitive detector, and the detection precision of the light spot position is improved.

Description

Technical Field

[0001] This application relates to the field of spot position detection technology, and in particular to a position detection circuit and a position detection system. Background Technology

[0002] In modern industry and technology, spot position detection technology plays a crucial role in several important applications, such as photolithography alignment in semiconductor manufacturing, precise position feedback in optical measurement, and object positioning in automated production lines. These applications require spot position detection to possess high precision, high stability, and high anti-interference capabilities to ensure the accuracy of the production process and product quality.

[0003] Existing spot position detection circuits typically employ a two-stage amplifier circuit. The first stage converts current to voltage, and the second stage amplifies the voltage signal. This design can only measure position along a single axis, cannot simultaneously acquire position information in two directions, and has low measurement accuracy and linearity. Furthermore, it has weak anti-interference capabilities in complex working environments and under long-distance signal transmission conditions, resulting in low spot position detection accuracy. Summary of the Invention

[0004] In view of this, the embodiments of this application provide at least one position detection circuit and position detection system, which improves signal stability and transmission distance by performing current-voltage conversion and differential signal transmission on the signals collected by the position-sensitive detector, thereby improving the detection accuracy of the spot position.

[0005] This application mainly includes the following aspects: In a first aspect, embodiments of this application provide a position detection circuit, which includes a position-sensitive detector, a current-to-voltage conversion circuit, and a differential conversion circuit; the current-to-voltage conversion circuit is electrically connected to both the position-sensitive detector and the differential conversion circuit; the differential conversion circuit is also connected to a signal acquisition circuit via a twisted-pair cable; wherein... The position-sensitive detector is used to convert the position of the light spot into current signals for each electrode; The current-to-voltage conversion circuit is used to acquire current signals from each electrode of the position-sensitive detector, convert the current signals of each electrode into voltage signals, and then send them to the differential circuit. The differential circuit is used to convert the voltage signals output by the current-to-voltage conversion circuit into differential signals, and transmit them to the signal acquisition circuit via twisted pair cable.

[0006] Furthermore, the current-to-voltage conversion circuit includes two voltage reference circuits, four transimpedance amplifier circuits, and four first resistors; wherein, each voltage reference circuit includes two sets of output terminals; the reference voltage output terminal of each set of output terminals is electrically connected to the inverting input terminal of a transimpedance amplifier circuit through a first resistor, and the bias voltage output terminal of each set of output terminals is electrically connected to the non-inverting input terminal of the same transimpedance amplifier circuit; the inverting input terminal of each transimpedance amplifier circuit is also connected to one electrode of the position-sensitive detector, and the output terminal of each transimpedance amplifier circuit is also connected to the differential circuit.

[0007] Further, any of the transimpedance amplifier circuits includes a first operational amplifier, a second resistor, a first capacitor, and a second capacitor; wherein, the inverting input terminal of the first operational amplifier is electrically connected to the first terminal of the second resistor, the first terminal of the first capacitor, the first terminal of the second capacitor, and the first resistor, respectively; the output terminal of the first operational amplifier is electrically connected to the second terminal of the second resistor, the second terminal of the first capacitor, the second terminal of the second capacitor, and the differential circuit, respectively; and the non-inverting input terminal of the first operational amplifier is electrically connected to the bias voltage output terminal of the voltage reference circuit.

[0008] Further, any of the voltage reference circuits includes a voltage reference source chip, a bootstrap filter circuit, a second operational amplifier, a third operational amplifier, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, and an eighth resistor; wherein, the bootstrap filter circuit is electrically connected to the output terminal of the voltage reference source chip and the non-inverting input terminal of the second operational amplifier; the inverting input terminal of the second operational amplifier is electrically connected to the output terminal of the second operational amplifier; the third resistor is electrically connected to the inverting input terminal of the second operational amplifier and the inverting input terminal of the third operational amplifier; the fourth resistor is electrically connected to the inverting input terminal of the third operational amplifier and the output terminal of the third operational amplifier; the third operational amplifier... The non-inverting input terminal of the device is grounded; the fifth resistor is electrically connected to the output terminal of the second operational amplifier and the first terminal of the sixth resistor; the second terminal of the sixth resistor is grounded; the seventh resistor is electrically connected to the output terminal of the third operational amplifier and the first terminal of the eighth resistor; the second terminal of the eighth resistor is grounded; the output terminal of the second operational amplifier is the reference voltage output terminal of the first group of output terminals of the voltage reference circuit, and the first terminal of the sixth resistor is the bias voltage output terminal of the first group of output terminals of the voltage reference circuit; the output terminal of the third operational amplifier is the reference voltage output terminal of the second group of output terminals of the voltage reference circuit, and the first terminal of the eighth resistor is the bias voltage output terminal of the second group of output terminals of the voltage reference circuit.

[0009] Furthermore, the bootstrap filter circuit includes a ninth resistor, a tenth resistor, a third capacitor, and a fourth capacitor; wherein, the first terminal of the ninth resistor is electrically connected to the first terminal of the tenth resistor and the output terminal of the voltage reference source chip, the second terminal of the ninth resistor is electrically connected to the first terminal of the third capacitor and the non-inverting input terminal of the second operational amplifier, the second terminal of the tenth resistor is electrically connected to the second terminal of the third capacitor and the first terminal of the fourth capacitor, and the second terminal of the fourth capacitor is grounded.

[0010] Furthermore, the differential converter includes four single-ended to differential converters; each single-ended to differential converter corresponds to a transimpedance amplifier circuit; each single-ended to differential converter includes a subtraction amplifier circuit, an inverting proportional amplifier circuit, and a filter circuit; wherein, the input terminals of the subtraction amplifier circuit and the inverting proportional amplifier circuit are electrically connected to the output terminals of the corresponding transimpedance amplifier circuits; the first input terminal of the filter circuit is electrically connected to the output terminal of the subtraction amplifier circuit, the second input terminal of the filter circuit is electrically connected to the output terminal of the inverting proportional amplifier circuit, and the first and second output terminals of the filter circuit are respectively connected to the signal acquisition circuit via twisted-pair cables.

[0011] Furthermore, the subtraction amplifier circuit includes a fourth operational amplifier, an eleventh resistor, a twelfth resistor, and a fifth capacitor; wherein, the non-inverting input terminal of the fourth operational amplifier and the first terminal of the eleventh resistor are electrically connected to the output terminal of the transimpedance amplifier circuit, the inverting input terminal of the fourth operational amplifier is electrically connected to the second terminal of the eleventh resistor, the first terminal of the twelfth resistor, and the first terminal of the fifth capacitor, respectively, and the output terminal of the fourth operational amplifier is electrically connected to the second terminal of the twelfth resistor, the second terminal of the fifth capacitor, and the first input terminal of the filter circuit, respectively.

[0012] Furthermore, the inverting proportional amplifier circuit includes a fifth operational amplifier, a thirteenth resistor, a fourteenth resistor, and a sixth capacitor; wherein, the first end of the thirteenth resistor is electrically connected to the output terminal of the transimpedance amplifier circuit; the inverting input terminal of the fifth operational amplifier is electrically connected to the second end of the thirteenth resistor, the first end of the fourteenth resistor, and the first end of the sixth capacitor, respectively; the non-inverting input terminal of the fifth operational amplifier is grounded; and the output terminal of the fifth operational amplifier is electrically connected to the second end of the fourteenth resistor, the second end of the sixth capacitor, and the second input terminal of the filter circuit, respectively.

[0013] Further, the filter circuit includes a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a seventh capacitor, and an eighth capacitor; wherein, the first end of the fifteenth resistor is electrically connected to the output end of the subtraction amplifier circuit, and the second end of the fifteenth resistor is electrically connected to the first end of the sixteenth resistor and the first end of the seventh capacitor; the second end of the seventh capacitor is grounded; the first end of the seventeenth resistor is electrically connected to the output end of the inverting proportional amplifier circuit, and the second end of the seventeenth resistor is electrically connected to the first end of the eighteenth resistor and the first end of the eighth capacitor; the second end of the eighth capacitor is grounded; the second ends of the sixteenth resistor and the eighteenth resistor are respectively connected to the signal acquisition circuit via twisted-pair cables.

[0014] Secondly, embodiments of this application also provide a position detection system, which includes a signal acquisition circuit and the position detection circuit described above; the signal acquisition circuit and the position detection circuit are connected via a twisted-pair cable; wherein... The signal acquisition circuit is used to calculate the position of the light spot based on the differential signal output by the position detection circuit.

[0015] This application provides a position detection circuit and a position detection system. The position detection circuit includes a position-sensitive detector, a current-to-voltage conversion circuit, and a differential conversion circuit. The current-to-voltage conversion circuit is electrically connected to both the position-sensitive detector and the differential conversion circuit. The differential conversion circuit is also connected to a signal acquisition circuit via a twisted-pair cable. The position-sensitive detector converts the spot position into current signals for each electrode. The current-to-voltage conversion circuit acquires current signals from each electrode of the position-sensitive detector, converts these current signals into voltage signals, and sends them to the differential conversion circuit. The differential conversion circuit converts the voltage signals output by the current-to-voltage conversion circuit into differential signals, which are then transmitted to the signal acquisition circuit via the twisted-pair cable. By performing current-to-voltage conversion and differential signal transmission on the signals acquired by the position-sensitive detector, signal stability and transmission distance are improved, thereby increasing the accuracy of spot position detection.

[0016] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of a position detection circuit provided in an embodiment of this application; Figure 2 This is a schematic diagram illustrating the working principle of the position-sensitive detector in the embodiments of this application; Figure 3 This is a schematic diagram of the structure of a current-to-voltage conversion circuit provided in an embodiment of this application; Figure 4 This is a schematic diagram of a transimpedance amplifier circuit provided in an embodiment of this application; Figure 5 This is one of the structural schematic diagrams of a voltage reference circuit provided in the embodiments of this application; Figure 6 This is a second schematic diagram of a voltage reference circuit provided in an embodiment of this application; Figure 7 This is a schematic diagram of a differential circuit provided in an embodiment of this application; Figure 8 This is a schematic diagram of a single-ended to differential circuit provided in an embodiment of this application; Figure 9 This is a schematic diagram of the structure of a position detection system provided in an embodiment of this application.

[0019] Explanation of key component symbols: In the diagram: 100 - Position detection circuit; 110 - Position-sensitive detector; 120 - Current-to-voltage conversion circuit; 130 - Differential converter circuit; 200 - Signal acquisition circuit; 121 - Voltage reference circuit; 122 - Transimpedance amplifier circuit; R1 - First resistor; A1 - First operational amplifier; R2 - Second resistor; C1 - First capacitor; C2 - Second capacitor; U1 - Voltage reference chip; 1211 - Bootstrap filter circuit; A2 - Second operational amplifier; A3 - Third operational amplifier; R3 - Third resistor; R4 - Fourth resistor; R5 - Fifth resistor; R6 - Sixth resistor; R7 - Seventh resistor; R8 - Eighth resistor; R9 - Ninth resistor Resistors; R10 - Tenth resistor; C3 - Third capacitor; C4 - Fourth capacitor; 131 - Single-ended to differential circuit; 1311 - Subtraction amplifier circuit; 1312 - Inverting proportional amplifier circuit; 1313 - Filter circuit; A4 - Fourth operational amplifier; R11 - Eleventh resistor; R12 - Twelfth resistor; C5 - Fifth capacitor; A5 - Fifth operational amplifier; R13 - Thirteenth resistor; R14 - Fourteenth resistor; C6 - Sixth capacitor; R15 - Fifteenth resistor; R16 - Sixteenth resistor; R17 - Seventeenth resistor; R18 - Eighteenth resistor; C7 - Seventh capacitor; C8 - Eighth capacitor; 20 - Position detection system. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0021] In the description of this application, it should be noted that the terms "inner" and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0022] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "setup" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0023] It is worth noting that prior to this application, existing spot position detection circuits typically employed a two-stage amplifier circuit. The first stage converted current to voltage, and the second stage amplified the voltage signal. This design could only measure single-axis position, failing to acquire position information in two directions simultaneously. Furthermore, it suffered from low measurement accuracy and linearity, and weak anti-interference capabilities under complex working environments and long-distance signal transmission conditions, resulting in low spot position detection accuracy.

[0024] To address the aforementioned problems, this application relates to a position detection circuit and a position detection system. The position detection circuit includes a position-sensitive detector, a current-to-voltage conversion circuit, and a differential conversion circuit. The current-to-voltage conversion circuit is electrically connected to both the position-sensitive detector and the differential conversion circuit. The differential conversion circuit is also connected to a signal acquisition circuit via a twisted-pair cable. The position-sensitive detector converts the spot position into current signals for each electrode. The current-to-voltage conversion circuit acquires current signals from each electrode of the position-sensitive detector, converts these current signals into voltage signals, and sends them to the differential conversion circuit. The differential conversion circuit converts the voltage signals output by the current-to-voltage conversion circuit into differential signals, which are then transmitted to the signal acquisition circuit via the twisted-pair cable. By performing current-to-voltage conversion and differential signal transmission on the signals acquired by the position-sensitive detector, signal stability and transmission distance are improved, thereby enhancing the accuracy of spot position detection.

[0025] To facilitate understanding of this application, the technical solutions provided in this application will be described in detail below with reference to specific embodiments.

[0026] Please see Figure 1 , Figure 1 This is one of the structural schematic diagrams of a position detection circuit provided in an embodiment of this application. Figure 1 As shown, the position detection circuit 100 includes a position-sensitive detector 110, a current-to-voltage conversion circuit 120, and a differential conversion circuit 130; the current-to-voltage conversion circuit 120 is electrically connected to both the position-sensitive detector 110 and the differential conversion circuit 130; the differential conversion circuit 130 is also connected to the signal acquisition circuit 200 via a twisted-pair cable; wherein, A position-sensitive detector 110 is used to convert the position of the light spot into current signals for each electrode; The current-to-voltage conversion circuit 120 is used to acquire current signals from each electrode of the position-sensitive detector 110, convert the current signals of each electrode into voltage signals, and then send them to the differential circuit 130. The differential circuit 130 is used to convert the various voltage signals output by the current-voltage conversion circuit 120 into differential signals and transmit them to the signal acquisition circuit 200 via twisted pair cable.

[0027] In this embodiment, the position detection circuit 110 is designed as a zero-position sensor preamplifier board. The position sensitive detector (PSD) 110 converts the optical signal reflecting the position information of the workpiece stage into a corresponding current signal, and the current signal is converted into a voltage signal and amplified by the current-to-voltage conversion circuit 120. Finally, after processing by the differential circuit 130, the signal is transmitted to the signal acquisition board 200 in the form of a differential signal via a twisted pair.

[0028] Specifically, please refer to Figure 2 , Figure 2 This is a schematic diagram illustrating the working principle of the position-sensitive detector in an embodiment of this application. Figure 2 As shown, the position-sensitive detector 110 in this embodiment of the application has two electrodes on the upper and lower surfaces of the photosensitive surface, with the upper surface being the anode. The lower surface is the cathode. When the PSD is subjected to energy of During laser irradiation, current flows from the cathode ( , ) flows into the device, from the anode ( , The current flows out of the device. The direction of the current is defined as the direction in which positive charges move.

[0029] Current flows in from the two cathodes on the lower surface, flows vertically upwards at the incident point of the light to the upper surface, and exits from the two electrodes on the upper surface. The lower and upper surfaces are equivalent to two resistors, and the position of the incident light point defines the current difference between the two cathodes and the anode. The magnitude of the electrode photocurrent is proportional to the distance between the electrode and the light point, and when the light energy is constant, the sum of the currents of the two electrodes is constant. Because the dual-sided electrode structure of the PSD in this embodiment eliminates crosstalk and nonlinearity, and the photosensitive surface of the PSD is a continuous and uniform resistive layer, the photocurrent generated by each electrode is inversely proportional to the distance from the light spot to the electrode, resulting in better linearity and extremely fast response speed, reaching the microsecond level.

[0030] Let's take the cathode current as an example: ; ; in, and Cathode and Electrode current; for and The sum of the incoming currents; In this embodiment of the application, the side length of the PSD photosensitive surface is given. The length is 4mm; It is the distance from the incident light point to the midpoint of the side length.

[0031] Similarly, the current at the anode is calculated in the same way as the current at the cathode, and the sum of the currents is the same as that at the cathode, both being... Therefore, the position coordinates of the light spot This can be obtained from the current in these four electrodes, and the calculation method is as follows: ; .

[0032] Therefore, the position-sensitive detector 110 in this embodiment can accurately convert the position of the light spot into a current signal, and realize two-dimensional position detection by using two electrodes to detect the current signals in the X and Y directions respectively, thus solving the problem that the prior art can only measure the position of a single axis.

[0033] The current-to-voltage conversion circuit 120 further improves the accuracy and stability of the measurement. By converting a weak current signal into a voltage signal, this circuit reduces errors in the signal conversion process and also reduces the impact of noise on the measurement results.

[0034] The differential circuit 130 effectively reduces noise interference during long-distance transmission by converting the voltage signal into a differential signal. The differential signal is transmitted via twisted-pair cable, further improving the signal's anti-interference capability and transmission stability. This design not only reduces signal distortion during transmission but also improves the overall system performance, making it suitable for high-precision measurements and complex working environments.

[0035] In summary, this application achieves dual-axis position detection by employing a position-sensitive detector 110, combined with high-precision current-to-voltage conversion and differential signal transmission technology, significantly improving the detection accuracy and stability of the light spot position. These combined techniques address the shortcomings of existing technologies, providing a reliable technical solution for high-precision light spot position detection.

[0036] In one possible implementation, the embodiments provided in this application are described below. Figure 1 An example of a possible circuit structure for the current-to-voltage conversion circuit 120 is provided. Please refer to [link / reference]. Figure 3 , Figure 3 This is a schematic diagram of a current-to-voltage conversion circuit provided in an embodiment of this application. Figure 3 As shown, the current-to-voltage conversion circuit 120 includes two voltage reference circuits 121, four transimpedance amplifier circuits 122, and four first resistors R1.

[0037] Each voltage reference circuit 121 includes two sets of output terminals; the reference voltage output terminal of each set of output terminals is electrically connected to the inverting input terminal of a transimpedance amplifier circuit 122 through a first resistor R1, and the bias voltage output terminal of each set of output terminals is electrically connected to the non-inverting input terminal of the same transimpedance amplifier circuit 122; the inverting input terminal of each transimpedance amplifier circuit 122 is also connected to an electrode of a position-sensitive detector 110, and the output terminal of each transimpedance amplifier circuit 122 is also connected to a differential circuit 130.

[0038] In this embodiment, the current-to-voltage conversion circuit 120 includes two voltage reference circuits 121, four transimpedance amplifier circuits 122, and four first resistors R1. Each voltage reference circuit 121 provides two sets of output terminals, each including a reference voltage output terminal and a bias voltage output terminal. The inverting input terminal of each transimpedance amplifier circuit 122 is connected to the reference voltage output terminal of the voltage reference circuit 121 through a first resistor R1, while its non-inverting input terminal is directly connected to the bias voltage output terminal of the voltage reference circuit 121. This connection method enables the transimpedance amplifier circuit 122 to accurately convert the residual current of the position-sensitive detector 110 electrode and the bias current into a voltage signal using the reference voltage and the bias voltage. By appropriately selecting the resistance value of the first resistor R1, the magnitude of the bias current can be precisely adjusted, thereby achieving high-precision current-to-voltage conversion.

[0039] This circuit structure not only improves the accuracy of signal conversion but also reduces measurement errors caused by power supply fluctuations or temperature changes through the stable output of the voltage reference circuit 121. Furthermore, the high gain and low noise characteristics of the transimpedance amplifier circuit 122 further ensure the accurate amplification of weak current signals, reducing the impact of noise on the measurement results. Through this design, the current-to-voltage conversion circuit 120 can stably convert the current signal output by the position-sensitive detector 110 into a voltage signal, providing a high-quality input signal for subsequent signal processing, thereby significantly improving the detection accuracy and reliability of the light spot position.

[0040] In one possible implementation, the embodiments provided in this application are described below. Figure 3 An example of a possible circuit structure for the transimpedance amplifier circuit 122 is provided. Please refer to [link / reference]. Figure 4 , Figure 4 This is a schematic diagram of a transimpedance amplifier circuit provided in an embodiment of this application. Figure 4 As shown, any transimpedance amplifier circuit 122 includes a first operational amplifier A1, a second resistor R2, a first capacitor C1, and a second capacitor C2; wherein, the inverting input terminal of the first operational amplifier A1 is electrically connected to the first terminal of the second resistor R2, the first terminal of the first capacitor C1, the first terminal of the second capacitor C2, and the first resistor R1, respectively; the output terminal of the first operational amplifier A1 is electrically connected to the second terminal of the second resistor R2, the second terminal of the first capacitor C1, the second terminal of the second capacitor C2, and the differential circuit 130, respectively; and the non-inverting input terminal of the first operational amplifier A1 is electrically connected to the bias voltage output terminal of the voltage reference circuit 121.

[0041] In this embodiment, the first operational amplifier A1 and the second resistor R2 constitute a transimpedance amplifier. The second resistor R2 is the feedback resistor of the transimpedance amplifier. Connecting the first capacitor C2 and the second capacitor C2 in parallel with R2 enables phase compensation, suppresses high-frequency noise, and improves circuit stability. Specifically, connecting multiple capacitors in parallel reduces the equivalent series resistance (ESR) of the circuit, thereby reducing capacitor consumption and improving filtering efficiency. Furthermore, connecting multiple capacitors in parallel reduces leakage current, making the circuit more stable. The first resistor R1 converts the bias voltage into a bias current.

[0042] Specifically, each electrode of the PSD in this embodiment can be considered as a constant current source with an impedance of PSD electrode output DC range: 125 uA. The transimpedance amplifier circuit 122 converts the PSD electrode current into voltage. The quiescent input current is 146uA, and the expected output range is -5V to +5V. The value of the second resistor R2 as the transimpedance is... Depend on The resistance value was chosen to be 64.9kΩ to compensate for the PSD offset. The simplest way to generate bias current is to use a resistor value that is biased to the input terminal of the trans-resistor. The first resistor R1, where, For the reference voltage output terminal, 5V (-5V) is preferred in this embodiment. The voltage at the bias voltage output terminal is preferably 2.5V (-2.5V) in this embodiment. and The symbols are consistent in the same transimpedance amplifier circuit 122.

[0043] After passing through a transimpedance amplifier, the photocurrent is converted into a voltage signal. The specific formula is shown below: ; ; ; ; In this way, the coordinate position of the light spot can be deduced from the voltage. : ; ; ; ; ; .

[0044] With this circuit structure, the transimpedance amplifier circuit 122 can accurately convert the weak current signal output by the position-sensitive detector 110 into a voltage signal. At the same time, frequency compensation and noise filtering are performed through the first capacitor C1 and the second capacitor C2 to reduce the impact of high-frequency noise on the measurement results, improve the signal quality and stability, and thus significantly improve the accuracy and reliability of spot position detection.

[0045] In one possible implementation, the embodiments provided in this application are described below. Figure 3 An example of a possible circuit structure for the voltage reference circuit 121 is provided. Please refer to [link / reference]. Figure 5 , Figure 5 This is one of the structural schematic diagrams of a voltage reference circuit provided in an embodiment of this application. For example... Figure 5 As shown, any voltage reference circuit 121 includes a voltage reference source chip U1, a bootstrap filter circuit 1211, a second operational amplifier A2, a third operational amplifier A3, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, and an eighth resistor R8. The bootstrap filter circuit 1211 is electrically connected to the output terminal of the voltage reference source chip U1 and the non-inverting input terminal of the second operational amplifier A2. The inverting input terminal of the second operational amplifier A2 is electrically connected to its output terminal. The third resistor R3 is electrically connected to both the inverting input terminals of the second and third operational amplifiers A2 and A3, respectively. The fourth resistor R4 is electrically connected to both the inverting input terminal and the output terminal of the third operational amplifier A3, respectively. The third operational amplifier A3 is connected to ground; the fifth resistor R5 is electrically connected to the output terminal of the second operational amplifier A2 and the first terminal of the sixth resistor R6 respectively; the second terminal of the sixth resistor R6 is grounded; the seventh resistor R7 is electrically connected to the output terminal of the third operational amplifier A3 and the first terminal of the eighth resistor R8 respectively; the second terminal of the eighth resistor R8 is grounded; the output terminal of the second operational amplifier A2 is the reference voltage output terminal of the first group of output terminals of the voltage reference circuit 121, and the first terminal of the sixth resistor R6 is the bias voltage output terminal of the first group of output terminals of the voltage reference circuit 121; the output terminal of the third operational amplifier A3 is the reference voltage output terminal of the second group of output terminals of the voltage reference circuit 121, and the first terminal of the eighth resistor R8 is the bias voltage output terminal of the second group of output terminals of the voltage reference circuit 121.

[0046] In this embodiment, the voltage reference circuit 121 provides a high-precision and stable reference voltage and bias voltage. The voltage reference source chip U1 uses an ADR293ER model to provide a stable reference voltage. The bootstrap filter circuit 1211 further filters out high-frequency noise in the reference voltage, ensuring its purity. The second operational amplifier A2 is configured as a voltage follower to buffer and stabilize the reference voltage, reducing load effects. The voltage follower provides the voltage... The third operational amplifier, A3, is configured as an inverting proportional amplifier to generate a negative reference voltage. Through a resistor divider network, the reference voltage is precisely divided into two parts, which serve as the positive half of the bias voltage. and negative half To maintain the highest accuracy, high-precision (1:1) resistor arrays are selected for the third resistor R3, fourth resistor R4, fifth resistor R5, sixth resistor R6, seventh resistor R7, and eighth resistor R8. This design not only improves the accuracy of the reference voltage and bias voltage but also ensures the stability of the voltage distribution through the high-precision resistor network. With this high-precision voltage reference circuit, this application can significantly improve the overall performance and reliability of the position detection circuit.

[0047] In one possible implementation, the embodiments provided in this application are described below. Figure 3 An example of a possible circuit structure for the voltage reference circuit 121 is provided. Please refer to [link / reference]. Figure 6 , Figure 6 This is a second schematic diagram of a voltage reference circuit provided in an embodiment of this application. Figure 6 As shown, the bootstrap filter circuit 1211 includes a ninth resistor R9, a tenth resistor R10, a third capacitor C3, and a fourth capacitor C4. The first terminal of the ninth resistor R9 is electrically connected to the first terminal of the tenth resistor R10 and the output terminal of the voltage reference source chip U1. The second terminal of the ninth resistor R9 is electrically connected to the first terminal of the third capacitor C3 and the non-inverting input terminal of the second operational amplifier A2. The second terminal of the tenth resistor R10 is electrically connected to the second terminal of the third capacitor C3 and the first terminal of the fourth capacitor C4. The second terminal of the fourth capacitor C4 is grounded.

[0048] In this embodiment, the ninth resistor R9 is used to set the operating point of the bootstrap filter circuit, ensuring the stability and accuracy of the circuit. The tenth resistor R10, together with the ninth resistor R9, forms a voltage divider network to adjust the input voltage of the bootstrap filter circuit to adapt to different operating conditions. The third capacitor C3, in conjunction with the ninth resistor R9 and the tenth resistor R10, forms a low-pass filter to filter out high-frequency noise and ensure the stability of the output voltage. The fourth capacitor C4, in conjunction with the tenth resistor R10, further stabilizes the output of the voltage reference circuit, reduces voltage fluctuations, and improves the circuit's anti-interference capability. Through this design of the bootstrap filter circuit 1211, high-frequency noise in the output voltage of the voltage reference source chip U1 can be effectively filtered out, ensuring the purity and stability of the reference voltage. This high-precision reference voltage provides a stable reference for the subsequent current-to-voltage conversion circuit 120, thereby improving the accuracy and reliability of the entire position detection circuit. By reasonably selecting the parameters of the ninth resistor R9, the tenth resistor R10, the third capacitor C3, and the fourth capacitor C4, the filtering effect can be further optimized, reducing the impact of noise on the measurement results.

[0049] In one possible implementation, the embodiments provided in this application are described below. Figure 1 An example of a possible circuit structure for the differential circuit 130 in the diagram is provided. Please refer to [link / reference]. Figure 7 , Figure 7 This is a schematic diagram of a differential circuit provided in an embodiment of this application. Figure 7 As shown, the differential converter 130 includes four single-ended to differential converters 131; each single-ended to differential converter 131 corresponds to a transimpedance amplifier circuit 122; any single-ended to differential converter 131 includes a subtraction amplifier circuit 1311, an inverting proportional amplifier circuit 1312, and a filter circuit 1313; wherein, the input terminals of the subtraction amplifier circuit 1311 and the inverting proportional amplifier circuit 1312 are electrically connected to the output terminals of the corresponding transimpedance amplifier circuit 122; the first input terminal of the filter circuit 1313 is electrically connected to the output terminal of the subtraction amplifier circuit 1311, the second input terminal of the filter circuit 1313 is electrically connected to the output terminal of the inverting proportional amplifier circuit 1312, and the first and second output terminals of the filter circuit 1313 are connected to the signal acquisition circuit 200 via twisted-pair cables.

[0050] In this embodiment, a single-ended to differential circuit 131 converts the single-ended signal output from the transimpedance amplifier circuit 122 into a differential signal suitable for twisted-pair transmission, enabling it to drive capacitive loads from long-distance cables. This circuit includes a non-inverting (gain 1) subtraction amplifier circuit 1311 and an inverting (gain -1) inverting proportional amplifier circuit 1312, resulting in a total voltage gain of 2. The capacitive load is driven by adjusting the bandwidth and phase amplitude of the op-amps. To avoid peaks caused by input poles, the feedback resistor should be less than or equal to 10K. The non-inverting (P) and inverting (N) amplifiers have the same noise gain, and the circuit consists of four identical 10K 0.1% resistors. The subtraction amplifier circuit 1311 subtracts a reference voltage from the voltage signal output from the corresponding transimpedance amplifier circuit 122, generating a portion of the differential signal. The inverting proportional amplifier circuit 1312 generates an inverted proportional signal of the output signal from the transimpedance amplifier circuit 122, serving as the other portion of the differential signal. The filter circuit 1313 filters the output signals of the subtraction amplifier 1311 and the inverting amplifier 1312, removing high-frequency noise and unwanted signal components to ensure the quality of the output signal. Through this design, the differential circuit 130 not only improves the signal quality but also extends the signal transmission distance, thereby significantly improving the accuracy and reliability of the spot position detection.

[0051] In one possible implementation, the embodiments provided in this application are described below. Figure 7 An example of a possible circuit structure for the single-ended to differential circuit 131 is provided. Please refer to [link / reference]. Figure 8 , Figure 8 This is a schematic diagram of a single-ended to differential circuit 131 provided in an embodiment of this application. Figure 8 As shown, the subtraction amplifier circuit 1311 includes a fourth operational amplifier A4, an eleventh resistor R11, a twelfth resistor R12, and a fifth capacitor C5. The non-inverting input terminal of the fourth operational amplifier A4 and the first terminal of the eleventh resistor R11 are electrically connected to the output terminal of the transimpedance amplifier circuit 122, respectively. The inverting input terminal of the fourth operational amplifier A4 is electrically connected to the second terminal of the eleventh resistor R11, the first terminal of the twelfth resistor R12, and the first terminal of the fifth capacitor C5, respectively. The output terminal of the fourth operational amplifier A4 is electrically connected to the second terminal of the twelfth resistor R12, the second terminal of the fifth capacitor C5, and the first input terminal of the filter circuit 1313, respectively.

[0052] In this embodiment, the subtraction amplifier circuit 1311 accurately subtracts a reference signal from the voltage signal output by the transimpedance amplifier circuit 122 to generate a portion of the differential signal. Eleventh resistor R11 and twelfth resistor R12 are used to set the gain of the subtraction amplifier, ensuring accurate signal conversion. Fifth capacitor C5 is used for frequency compensation, reducing the impact of high-frequency noise on the signal and improving signal quality and stability. Through this high-precision signal processing, the subtraction amplifier circuit 1311 provides a high-quality input signal for subsequent differential signal transmission, thereby significantly improving the accuracy and reliability of spot position detection.

[0053] In one possible implementation, such as Figure 8 As shown, the inverting amplifier circuit 1312 includes a fifth operational amplifier A5, a thirteenth resistor R13, a fourteenth resistor R14, and a sixth capacitor C6; wherein, the first terminal of the thirteenth resistor R13 is electrically connected to the output terminal of the transimpedance amplifier circuit 122; the inverting input terminal of the fifth operational amplifier A5 is electrically connected to the second terminal of the thirteenth resistor R13, the first terminal of the fourteenth resistor R14, and the first terminal of the sixth capacitor C6, respectively; the non-inverting input terminal of the fifth operational amplifier A5 is grounded; and the output terminal of the fifth operational amplifier A5 is electrically connected to the second terminal of the fourteenth resistor R14, the second terminal of the sixth capacitor C6, and the second input terminal of the filter circuit 1313, respectively.

[0054] In this embodiment, the inverting amplifier circuit 1312 generates an inverted proportional signal to the output signal of the transimpedance amplifier circuit 122, serving as another part of the differential signal. The thirteenth resistor R13 and the fourteenth resistor R14 are used to set the gain of the inverting amplifier, ensuring accurate signal conversion. The sixth capacitor C6 is used for frequency compensation, reducing the impact of high-frequency noise on the signal and improving signal quality and stability. Through this high-precision signal processing, the inverting amplifier circuit 1312 provides a high-quality input signal for subsequent differential signal transmission, thereby significantly improving the accuracy and reliability of spot position detection.

[0055] In one possible implementation, such as Figure 8As shown, the filter circuit 1313 includes a fifteenth resistor R15, a sixteenth resistor R16, a seventeenth resistor R17, an eighteenth resistor R18, a seventh capacitor C7, and an eighth capacitor C8. The first terminal of the fifteenth resistor R15 is electrically connected to the output terminal of the subtraction amplifier circuit 1311, and the second terminal of the fifteenth resistor R15 is electrically connected to the first terminal of the sixteenth resistor R16 and the first terminal of the seventh capacitor C7, respectively. The second terminal of the seventh capacitor C7 is grounded. The first terminal of the seventeenth resistor R17 is electrically connected to the output terminal of the inverting proportional amplifier circuit 1312, and the second terminal of the seventeenth resistor R17 is electrically connected to the first terminal of the eighteenth resistor R18 and the first terminal of the eighth capacitor C8, respectively. The second terminal of the eighth capacitor C8 is grounded. The second terminals of the sixteenth resistor R16 and the eighteenth resistor R18 are connected to the signal acquisition circuit 200 via twisted-pair cables.

[0056] In this embodiment, the filter circuit 1313 effectively filters out high-frequency noise, ensuring the purity and stability of the differential signal. The fifteenth resistor R15 and the sixteenth resistor R16, along with the seventh capacitor C7, form a π-type low-pass filter to filter out high-frequency noise in the output signal of the subtraction amplifier circuit 1311. Similarly, the seventeenth resistor R17 and the eighteenth resistor R18, along with the eighth capacitor C8, form another π-type low-pass filter to filter out high-frequency noise in the output signal of the inverting proportional amplifier circuit 1312. Through these two low-pass filters, the filter circuit 1313 significantly reduces noise interference and improves signal quality. Finally, the filtered differential signal is transmitted to the signal acquisition circuit 200 via a twisted pair cable, ensuring signal stability and anti-interference capability during long-distance transmission. This design not only improves signal quality but also extends the signal transmission distance, thereby significantly improving the accuracy and reliability of spot position detection.

[0057] Furthermore, although an operational amplifier can drive an infinite capacitive load, it will still have a slight effect on the phase shift. To avoid excessive capacitive load at the output of the operational amplifier affecting the circuit, a 50Ω resistor can be connected in series.

[0058] This application provides a position detection circuit 100, including a position-sensitive detector 110, a current-to-voltage conversion circuit 120, and a differential conversion circuit 130. The current-to-voltage conversion circuit 120 is electrically connected to both the position-sensitive detector 110 and the differential conversion circuit 130. The differential conversion circuit 130 is also connected to a signal acquisition circuit 200 via a twisted-pair cable. The position-sensitive detector 110 converts the spot position into current signals for each electrode. The current-to-voltage conversion circuit 120 acquires current signals from each electrode of the position-sensitive detector 110, converts these current signals into voltage signals, and sends them to the differential conversion circuit 130. The differential conversion circuit 130 converts the voltage signals output by the current-to-voltage conversion circuit 120 into differential signals, which are then transmitted to the signal acquisition circuit 200 via the twisted-pair cable. By performing current-to-voltage conversion and differential signal transmission on the signals acquired by the position-sensitive detector, signal stability and transmission distance are improved, thereby increasing the accuracy of spot position detection.

[0059] Here, this application embodiment also provides a location detection system. Please refer to... Figure 9 , Figure 9 This is a schematic diagram of the structure of a position detection system provided in an embodiment of this application. Figure 9 As shown, the position detection system 20 includes a signal acquisition circuit 200 and a position detection circuit 100 provided in the above embodiment; the signal acquisition circuit 200 and the position detection circuit 100 are connected via a twisted pair cable; wherein, The signal acquisition circuit 200 is used to calculate the position of the light spot based on the differential signal output by the position detection circuit 100.

[0060] In this embodiment, the differential receiver of the signal acquisition circuit 200 eliminates common-mode interference from the sensor and converts the signal into a single-ended signal. After filtering and voltage division, the signal can be used for AD conversion to calculate the spot position. Synchronous sampling by the signal acquisition circuit 200 eliminates errors caused by laser intensity fluctuations.

[0061] It should be noted that, where there is no conflict, the features in the embodiments of this application can be combined with each other.

[0062] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A position detection circuit, characterized in that, The position detection circuit includes a position-sensitive detector, a current-to-voltage conversion circuit, and a differential conversion circuit; the current-to-voltage conversion circuit is electrically connected to both the position-sensitive detector and the differential conversion circuit; the differential conversion circuit is also connected to the signal acquisition circuit via a twisted-pair cable. The position-sensitive detector is used to convert the position of the light spot into current signals for each electrode; The current-to-voltage conversion circuit is used to acquire current signals from each electrode of the position-sensitive detector, convert the current signals of each electrode into voltage signals, and then send them to the differential circuit. The differential circuit is used to convert the voltage signals output by the current-to-voltage conversion circuit into differential signals, and transmit them to the signal acquisition circuit via twisted pair cable.

2. The position detection circuit according to claim 1, characterized in that, The current-to-voltage conversion circuit includes two voltage reference circuits, four transimpedance amplifier circuits, and four first resistors. Each voltage reference circuit includes two sets of output terminals. The reference voltage output terminal of each set of output terminals is electrically connected to the inverting input terminal of a transimpedance amplifier circuit through a first resistor, and the bias voltage output terminal of each set of output terminals is electrically connected to the non-inverting input terminal of the same transimpedance amplifier circuit. The inverting input terminal of each transimpedance amplifier circuit is also connected to one electrode of the position-sensitive detector, and the output terminal of each transimpedance amplifier circuit is also connected to the differential circuit.

3. The position detection circuit according to claim 2, characterized in that, Any of the transimpedance amplifier circuits includes a first operational amplifier, a second resistor, a first capacitor, and a second capacitor; wherein, the inverting input terminal of the first operational amplifier is electrically connected to the first terminal of the second resistor, the first terminal of the first capacitor, the first terminal of the second capacitor, and the first resistor, respectively; the output terminal of the first operational amplifier is electrically connected to the second terminal of the second resistor, the second terminal of the first capacitor, the second terminal of the second capacitor, and the differential circuit, respectively; and the non-inverting input terminal of the first operational amplifier is electrically connected to the bias voltage output terminal of the voltage reference circuit.

4. The position detection circuit according to claim 2, characterized in that, Any of the voltage reference circuits includes a voltage reference source chip, a bootstrap filter circuit, a second operational amplifier, a third operational amplifier, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, and an eighth resistor; wherein, the bootstrap filter circuit is electrically connected to the output terminal of the voltage reference source chip and the non-inverting input terminal of the second operational amplifier; the inverting input terminal of the second operational amplifier is electrically connected to the output terminal of the second operational amplifier; the third resistor is electrically connected to the inverting input terminal of the second operational amplifier and the inverting input terminal of the third operational amplifier; the fourth resistor is electrically connected to the inverting input terminal of the third operational amplifier and the output terminal of the third operational amplifier; the third operational amplifier... The non-inverting input terminal is grounded; the fifth resistor is electrically connected to the output terminal of the second operational amplifier and the first terminal of the sixth resistor; the second terminal of the sixth resistor is grounded; the seventh resistor is electrically connected to the output terminal of the third operational amplifier and the first terminal of the eighth resistor; the second terminal of the eighth resistor is grounded; the output terminal of the second operational amplifier is the reference voltage output terminal of the first group of output terminals of the voltage reference circuit, and the first terminal of the sixth resistor is the bias voltage output terminal of the first group of output terminals of the voltage reference circuit; the output terminal of the third operational amplifier is the reference voltage output terminal of the second group of output terminals of the voltage reference circuit, and the first terminal of the eighth resistor is the bias voltage output terminal of the second group of output terminals of the voltage reference circuit.

5. The position detection circuit according to claim 4, characterized in that, The bootstrap filter circuit includes a ninth resistor, a tenth resistor, a third capacitor, and a fourth capacitor; wherein, the first end of the ninth resistor is electrically connected to the first end of the tenth resistor and the output terminal of the voltage reference source chip, the second end of the ninth resistor is electrically connected to the first end of the third capacitor and the non-inverting input terminal of the second operational amplifier, the second end of the tenth resistor is electrically connected to the second end of the third capacitor and the first end of the fourth capacitor, and the second end of the fourth capacitor is grounded.

6. The position detection circuit according to claim 2, characterized in that, The differential converter circuit includes four single-ended to differential converter circuits; each single-ended to differential converter circuit corresponds to a transimpedance amplifier circuit; each single-ended to differential converter circuit includes a subtraction amplifier circuit, an inverting proportional amplifier circuit, and a filter circuit; wherein, the input terminals of the subtraction amplifier circuit and the inverting proportional amplifier circuit are electrically connected to the output terminals of the corresponding transimpedance amplifier circuits; the first input terminal of the filter circuit is electrically connected to the output terminal of the subtraction amplifier circuit, the second input terminal of the filter circuit is electrically connected to the output terminal of the inverting proportional amplifier circuit, and the first and second output terminals of the filter circuit are respectively connected to the signal acquisition circuit via twisted-pair cables.

7. The position detection circuit according to claim 6, characterized in that, The subtraction amplifier circuit includes a fourth operational amplifier, an eleventh resistor, a twelfth resistor, and a fifth capacitor; wherein, the non-inverting input terminal of the fourth operational amplifier and the first terminal of the eleventh resistor are electrically connected to the output terminal of the transimpedance amplifier circuit, the inverting input terminal of the fourth operational amplifier is electrically connected to the second terminal of the eleventh resistor, the first terminal of the twelfth resistor, and the first terminal of the fifth capacitor, and the output terminal of the fourth operational amplifier is electrically connected to the second terminal of the twelfth resistor, the second terminal of the fifth capacitor, and the first input terminal of the filter circuit.

8. The position detection circuit according to claim 6, characterized in that, The inverting proportional amplifier circuit includes a fifth operational amplifier, a thirteenth resistor, a fourteenth resistor, and a sixth capacitor; wherein, the first end of the thirteenth resistor is electrically connected to the output terminal of the transimpedance amplifier circuit; the inverting input terminal of the fifth operational amplifier is electrically connected to the second end of the thirteenth resistor, the first end of the fourteenth resistor, and the first end of the sixth capacitor, respectively; the non-inverting input terminal of the fifth operational amplifier is grounded; and the output terminal of the fifth operational amplifier is electrically connected to the second end of the fourteenth resistor, the second end of the sixth capacitor, and the second input terminal of the filter circuit, respectively.

9. The position detection circuit according to claim 6, characterized in that, The filter circuit includes a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a seventh capacitor, and an eighth capacitor. The first terminal of the fifteenth resistor is electrically connected to the output terminal of the subtraction amplifier circuit, and the second terminal of the fifteenth resistor is electrically connected to the first terminal of the sixteenth resistor and the first terminal of the seventh capacitor. The second terminal of the seventh capacitor is grounded. The first terminal of the seventeenth resistor is electrically connected to the output terminal of the inverting proportional amplifier circuit, and the second terminal of the seventeenth resistor is electrically connected to the first terminal of the eighteenth resistor and the first terminal of the eighth capacitor. The second terminal of the eighth capacitor is grounded. The second terminals of the sixteenth and eighteenth resistors are respectively connected to the signal acquisition circuit via twisted-pair cables.

10. A position detection system, characterized in that, The position detection system includes a signal acquisition circuit and a position detection circuit as described in any one of claims 1-9; the signal acquisition circuit and the position detection circuit are connected via a twisted-pair cable; wherein... The signal acquisition circuit is used to calculate the position of the light spot based on the differential signal output by the position detection circuit.

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