A voltage divider circuit for photomultiplier tube

Abstract

The present invention provides a voltage divider circuit for a photomultiplier tube, comprising: a plurality of voltage divider units, connected in series in sequence, the connection point of two adjacent voltage divider units is used to connect a dynode of the photomultiplier tube, and at least part of the voltage divider units are set as adjustable units, each adjustable unit comprises: a voltage divider resistor; and an adjustable constant current source circuit, connected in parallel with the voltage divider resistor, configured so that its own current size is controlled and adjustable, thereby changing the current proportion flowing through the voltage divider resistor in the total current flowing through the adjustable unit, and realizing the adjustment of the voltage at both ends of the voltage divider resistor. The advantage of the present invention is that the voltage divider relationship of the voltage divider circuit can be made adjustable, thereby optimizing its response characteristics.

Description

Technical Field

[0001] The invention relates to the field of photoelectric detection, and in particular to a voltage divider circuit for a photomultiplier tube. Background Art

[0002] Photomultiplier Tube (PMT) is a highly sensitive photoelectric detection device. Its structure mainly includes a cathode chamber and a secondary emission multiplication system composed of several dynodes. By applying a gradually increasing DC voltage to each dynode and anode, the multiplication of secondary electrons is achieved, thereby enhancing the detection sensitivity of the light signal.

[0003] The voltage divider circuit design of traditional photomultiplier tubes generally relies on components such as resistor voltage dividers, voltage regulator diodes or triodes to form a fixed voltage distribution ratio. However, the non-adjustability of the fixed voltage divider relationship limits the photomultiplier tube to operate only under a specific voltage divider ratio, resulting in the photomultiplier tube's response characteristics not being able to reach the optimal state, affecting the quality of signal acquisition and the signal-to-noise ratio. Summary of the invention

[0004] An object of the present invention is to overcome at least one technical defect in the prior art and provide a voltage divider circuit for a photomultiplier tube.

[0005] A further object of the present invention is to make the voltage division relationship of the voltage division circuit adjustable so as to optimize its response characteristics.

[0006] Another further object of the present invention is to improve the accuracy and flexibility of voltage distribution in a voltage divider circuit.

[0007] A further object of the present invention is to enhance the anti-interference capability of the voltage divider circuit and improve its reliability and safety.

[0008] In particular, the present invention provides a voltage divider circuit for a photomultiplier tube, comprising:

[0009] A plurality of voltage divider units are connected in series in sequence, and a connection point of two adjacent voltage divider units is used to connect a dynode of the photomultiplier tube, and at least part of the voltage divider units are configured as adjustable units, and each of the adjustable units comprises:

[0010] Voltage divider resistors; and

[0011] The adjustable constant current source circuit is connected in parallel with the voltage dividing resistor and is configured so that its own current size is controllable and adjustable, thereby changing the current proportion flowing through the voltage dividing resistor in the total current flowing through the adjustable unit, thereby adjusting the voltage across the voltage dividing resistor.

[0012] Optionally, the adjustable constant current source circuit includes:

[0013] an adjustable resistor, a first end of which is connected to the first end of the voltage dividing resistor;

[0014] A first transistor, a first end of which is connected to the second end of the adjustable resistor, and a third end of which is connected to the second end of the voltage-dividing resistor;

[0015] a second transistor, a first end of which is connected to the first end of the adjustable resistor, and a second end of which is connected to the second end of the first transistor; and

[0016] A first resistor has a first end connected to the second end and the third end of the second transistor respectively, and a second end connected to the second end of the voltage dividing resistor.

[0017] Optionally, both the first transistor and the second transistor are NPN transistors, and the first end of each NPN transistor is an emitter, the second end is a base, and the third end is a collector; or

[0018] The first transistor and the second transistor are both PNP transistors, the first end of each PNP transistor is a collector, the second end is a base, and the third end is an emitter; or

[0019] The first transistor and the second transistor are both NMOS transistors or both PMOS transistors, and the first end of each NMOS transistor or PMOS transistor is a source, the second end is a gate, and the third end is a drain.

[0020] Optionally, the adjustable constant current source circuit further includes:

[0021] a third transistor, a first terminal of which is connected to the second terminal of the second transistor, and a third terminal of which is connected to the second terminal of the voltage-dividing resistor;

[0022] Furthermore, the first end of the first resistor is adjusted to be connected to the third end of the second transistor and the second end of the third transistor respectively.

[0023] Optionally, the third transistor is an NPN transistor, the first end of the NPN transistor is an emitter, the second end is a base, and the third end is a collector; or

[0024] The third transistor is a PNP transistor, the first end of the PNP transistor is a collector, the second end is a base, and the third end is an emitter; or

[0025] The third transistor is an NMOS transistor or a PMOS transistor, the first end of the NMOS transistor or the PMOS transistor is a source, the second end is a gate, and the third end is a drain.

[0026] Optionally, the adjustable constant current source circuit further includes:

[0027] A fuse has a first end connected to the first end of the adjustable resistor and a second end connected to the emitter of the second transistor.

[0028] Optionally, the adjustable resistor is a digital potentiometer, and the adjustable constant current source circuit further includes:

[0029] The control subcircuit is connected to the instruction interface of the digital potentiometer and is configured to send a resistance adjustment instruction to the digital potentiometer.

[0030] Optionally, the control subcircuit includes:

[0031] A controller, configured to output the resistance adjustment instruction; and

[0032] The isolation device has an input side connected to the controller and an output side connected to the instruction interface of the digital potentiometer, and is configured to perform signal isolation on the resistance adjustment instruction.

[0033] Optionally, the isolation device is a photoelectric isolator or an isolation transformer.

[0034] Optionally, the digital potentiometer has a main power pin and a logic power pin, and the adjustable constant current source circuit further includes a power supply circuit, and the power supply circuit includes:

[0035] A first voltage stabilizing diode, an anode terminal of which is connected to the first end of the voltage dividing resistor;

[0036] A first current limiting resistor, a first end of which is connected to the cathode end of the first voltage stabilizing diode, and a second end of which is connected to the second end of the voltage dividing resistor;

[0037] A second voltage stabilizing diode, an anode terminal of which is connected to the first end of the voltage dividing resistor; and

[0038] A second current limiting resistor, a first end of which is connected to the cathode end of the second voltage stabilizing diode, and a second end of which is connected to the second end of the voltage dividing resistor;

[0039] The main power supply pin of the digital potentiometer is connected to the cathode terminal of the first Zener diode, and the logic power supply pin is connected to the cathode terminal of the second Zener diode.

[0040] The voltage divider circuit for the photomultiplier tube of the present invention has some or all of its voltage divider units adjustable, each adjustable unit includes a voltage divider resistor and an adjustable constant current source circuit, and the adjustable constant current source circuit can make its own current size controlled and adjustable, so that the current ratio flowing through the voltage divider resistor can be dynamically changed, thereby realizing the adjustment of the voltage at both ends of the voltage divider resistor. In this way, the voltage division relationship of the entire voltage divider circuit is no longer fixed, but can be adjusted as needed, which will allow the photomultiplier tube to work under different voltage division ratios, optimize its response characteristics, ensure the accuracy and quality of signal acquisition, and also significantly improve the signal-to-noise ratio.

[0041] Furthermore, in the voltage divider circuit for a photomultiplier tube of the present invention, the adjustable resistor adopts a digital potentiometer, which can achieve accurate adjustment of the resistance value, ensure that the voltage distribution in the voltage divider circuit is more accurate, and thus meet the requirements of the photomultiplier tube under different working conditions. Through the integrated control subcircuit, a resistance adjustment instruction can be sent to the digital potentiometer in real time, so that the voltage division relationship of the voltage divider circuit can be adjusted instantly and flexibly, giving the photomultiplier tube the ability to quickly adapt to various working environments and signal strengths.

[0042] Furthermore, in the voltage divider circuit for a photomultiplier tube of the present invention, the controller can output accurate resistance adjustment instructions, and the isolation device can isolate and block the direct electrical connection between the controller and the digital potentiometer, thereby preventing electrical interference and signal crosstalk, and improving the anti-interference ability and stability of the voltage divider circuit. When a circuit fails or is abnormal, the isolation device can quickly cut off the electrical connection to prevent the fault from spreading, so that the voltage divider circuit has higher reliability and safety.

[0043] Based on the following detailed description of specific embodiments of the present invention in conjunction with the accompanying drawings, those skilled in the art will become more aware of the above and other objects, advantages and features of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0045] Figure 1 is a schematic structural diagram of a photomultiplier tube and a voltage divider circuit according to an embodiment of the present invention;

[0046] Figure 2 is a schematic structural diagram of an adjustable unit according to an embodiment of the present invention;

[0047] Figure 3is a schematic circuit diagram of an adjustable constant current source circuit according to an embodiment of the present invention;

[0048] Figure 4 Is adopted Figure 3 A schematic circuit diagram of a voltage divider circuit of an adjustable constant current source circuit;

[0049] Figure 5 is a schematic circuit diagram of an adjustable constant current source circuit according to another embodiment of the present invention;

[0050] Figure 6 is a schematic circuit diagram of an adjustable constant current source circuit according to another embodiment of the present invention;

[0051] Figure 7 Is adopted Figure 5 and Figure 6 A schematic circuit diagram of a voltage divider circuit of an adjustable constant current source circuit;

[0052] Figure 8 is a schematic circuit diagram of a voltage divider circuit according to another embodiment of the present invention;

[0053] Fig. 9 is a schematic circuit diagram of a voltage divider circuit according to yet another embodiment of the present invention;

[0054] Fig.10 is a schematic structural diagram of a digital potentiometer according to an optional embodiment of the present invention;

[0055] Fig.11 is a schematic circuit diagram of a power supply circuit according to an embodiment of the present invention;

[0056] Fig.12 is a schematic circuit diagram of a control subcircuit according to an embodiment of the present invention;

[0057] Fig.13 is a schematic circuit diagram of a control subcircuit according to another embodiment of the present invention.

[0058] Reference numerals: 10, voltage-dividing resistor; 20, adjustable constant current source circuit; 210, power supply circuit; 220, control subcircuit. DETAILED DESCRIPTION

[0059] Reference will now be made in detail to embodiments of the present invention, one or more examples of which are illustrated in the accompanying drawings. The various embodiments provided are intended to explain the present invention, not to limit the present invention. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made to the present invention without departing from the scope or spirit of the present invention. For example, a feature illustrated or described as a part of one embodiment may be used together with another embodiment to produce yet another embodiment. Therefore, the present invention is intended to cover such modifications and variations within the scope of the appended claims and their equivalents.

[0060] Refer to the following Figures 1 to 13 The voltage divider circuit for a photomultiplier tube of an embodiment of the present invention is described. The directions or positional relationships indicated by "inside", "outside", "upper", "lower", "top", "bottom", "horizontal", "vertical", etc. are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention.

[0061] In the description of this embodiment, it should be understood that the term "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined. When a feature "includes or contains" one or some of the features it covers, unless otherwise specifically described, this indicates that other features are not excluded and may further include other features.

[0062] In the description of the present embodiment, the description with reference to the terms "one embodiment", "some embodiments", "some examples", "an example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0063] The present invention provides a voltage divider circuit for a photomultiplier tube. Figure 1 is a schematic structural diagram of a photomultiplier tube and a voltage divider circuit according to an embodiment of the present invention.

[0064] like Figure 1 As shown, the photomultiplier tube may generally include a photocathode K, an electron multiplication system and an anode P. The electron multiplication system is composed of the 1st to Nth dynodes, and in this example N=10, but the present invention is not limited thereto, and N may also be any other positive integer. Specifically, in this embodiment, the 1st to 10th dynodes are respectively named as dynodes Dy1, Dy2, Dy3 to Dy10.

[0065] The voltage divider circuit includes a plurality of voltage divider units, such as voltage divider units 1 to 10, which are sequentially connected in series, and the connection point of two adjacent voltage divider units is used to connect a dynode of the photomultiplier tube. In this way, each dynode (such as Dy1, Dy2, Dy3 to Dy10) is powered or receives a corresponding electrical signal through the voltage of a specific voltage divider unit connection point, ensuring that the electron multiplication system can work stably and efficiently.

[0066] In particular, in this embodiment, at least part of the voltage dividing units are configured as adjustable units. Figure 2 is a schematic structural diagram of an adjustable unit according to an embodiment of the present invention, such as Figure 2 As shown, each adjustable unit includes a voltage divider resistor 10 and an adjustable constant current source circuit 20, wherein the adjustable constant current source circuit 20 is connected in parallel with the voltage divider resistor 10 and is configured so that its own current size is controlled and adjustable, thereby changing the proportion of the current flowing through the voltage divider resistor 10 in the total current flowing through the adjustable unit, thereby achieving the adjustment of the voltage across the voltage divider resistor 10.

[0067] The voltage divider circuit of this embodiment has some or all of its voltage divider units that are adjustable. Each adjustable unit includes a voltage divider resistor 10 and an adjustable constant current source circuit 20. The adjustable constant current source circuit 20 can control and adjust its own current size, so that the current ratio flowing through the voltage divider resistor 10 can be dynamically changed, thereby achieving the adjustment of the voltage across the two ends of the voltage divider resistor 10.

[0068] In this way, the voltage division relationship of the entire voltage divider circuit is no longer fixed, but can be adjusted as needed, which will allow the photomultiplier tube to operate under different voltage division ratios, optimize its response characteristics, ensure the accuracy and quality of signal acquisition, and significantly improve the signal-to-noise ratio.

[0069] The adjustable constant current source circuit 20 may include an adjustable resistor RT, a first transistor Q1, a second transistor Q2, and a first resistor R L The first end of the adjustable resistor RT is connected to the first end of the voltage-dividing resistor 10, the first end of the first transistor Q1 is connected to the second end of the adjustable resistor RT, the third end of the first transistor Q1 is connected to the second end of the voltage-dividing resistor 10, the first end of the second transistor Q2 is connected to the first end of the adjustable resistor RT, the second end of the second transistor Q2 is connected to the second end of the first transistor Q1, and the first resistor R L The first end of the first resistor R L The second end of is connected to the second end of the voltage dividing resistor 10.

[0070] The adjustable constant current source circuit 20 in this embodiment is implemented based on the current mirror principle. The adjustable resistor RT is used to adjust the current of the constant current source. The first transistor Q1 and the second transistor Q2 form a feedback loop for stabilizing the current. The first resistor R L Reference voltage for current feedback.

[0071] In one example, the first transistor Q1 and the second transistor Q2 are both NPN transistors. Accordingly, the first end of each NPN transistor is an emitter, the second end is a base, and the third end is a collector.

[0072] In another example, the first transistor Q1 and the second transistor Q2 may also be PNP transistors. Accordingly, the first end of each PNP transistor is a collector, the second end is a base, and the third end is an emitter.

[0073] In another example, the first transistor Q1 and the second transistor Q2 may both be NMOS transistors or PMOS transistors. Accordingly, the first terminal of each NMOS transistor or PMOS transistor is a source, the second terminal is a gate, and the third terminal is a drain.

[0074] Figure 3 is a schematic circuit diagram of an adjustable constant current source circuit 20 according to an embodiment of the present invention, in which the first transistor Q1 and the second transistor Q2 are both NPN transistors. Figure 4 Is adopted Figure 3 Schematic circuit diagram of the voltage divider circuit of the adjustable constant current source circuit 20.

[0075] exist Figure 4 In the embodiment, the voltage divider circuit includes a power supply DC, a resistor R1, a capacitor C1 and a plurality of voltage divider units, wherein the capacitor C1 is connected in parallel to both ends of the power supply DC and the resistor R1, and each voltage divider unit includes a voltage divider resistor 10, namely resistors R2 to R12, and the resistance value of the voltage divider resistor 10 determines the voltage on each dynode. The adjustable constant current source circuit 20 is connected in parallel with the resistor R7, and the current ratio flowing through the resistor R7 can be changed by adjusting the current of the constant current source, thereby realizing the adjustment of the voltage across the resistor R7.

[0076] Assume that the current flowing through the resistors R1 to R7 is ik when the adjustable constant current source circuit 20 is not connected in parallel. After the adjustable constant current source circuit 20 is connected in parallel, the current ik is decomposed into the current ik1 flowing through the resistor R7 and the current ik2 flowing through the adjustable constant current source circuit 20. At this time, the voltage between the dynodes Dy5 and Dy6 changes from ik*R7 to ik1*R7. According to the current mirror principle, the output current ik2 = (Ube_Q6-Ube_Q7) / RT; and there is a numerical relationship between ik1 and ik2, ik1 = ik-ik2, so that the current ik2 can be adjusted by adjusting the size of the resistor RT, and then the current ik1 can be adjusted to change the voltage between Dy5 and Dy6.

[0077] Figure 5 is a schematic circuit diagram of an adjustable constant current source circuit 20 according to another embodiment of the present invention. Figure 5 As shown, the adjustable constant current source circuit 20 may further include a third transistor Q3, a first end of the third transistor Q3 is connected to the second end of the second transistor Q2, a third end of the third transistor Q3 is connected to the second end of the voltage dividing resistor 10, and the first resistor R L The first end of is adjusted to be connected to the third end of the second transistor Q2 and the second end of the third transistor Q3 respectively.

[0078] In one example, the third transistor Q3 is an NPN transistor. Accordingly, the first terminal of the NPN transistor is an emitter, the second terminal is a base, and the third terminal is a collector.

[0079] In another example, the third transistor Q3 may also be a PNP transistor. Accordingly, the first end of the PNP transistor is the collector, the second end is the base, and the third end is the emitter.

[0080] In yet another example, the third transistor Q3 may also be an NMOS transistor or a PMOS transistor. Accordingly, the first terminal of the NMOS transistor or the PMOS transistor is a source, the second terminal is a gate, and the third terminal is a drain.

[0081] Figure 6 is a schematic structural diagram of an adjustable constant current source circuit 20 according to another embodiment of the present invention, as shown Figure 6 As shown, the adjustable constant current source circuit 20 may further include a fuse R, a first end of the fuse R is connected to a first end of the adjustable resistor RT, and a second end of the fuse R is connected to an emitter of the second transistor Q2.

[0082] Figure 7 Is adopted Figure 5 and Figure 6 A schematic circuit diagram of a voltage divider circuit of an adjustable constant current source circuit 20, wherein: Figure 5The adjustable constant current source circuit 20 shown is connected in parallel to both ends of the resistor R3 to adjust the voltage across the resistor R3. Figure 6 The adjustable constant current source circuit 20 shown is connected in parallel to both ends of the resistor R7 to adjust the voltage across the resistor R7.

[0083] It should be noted that, in the voltage divider circuit shown in this embodiment, the number of the adjustable constant current source circuits 20 and the specific positions of the adjustable constant current source circuits 20 in parallel are not limited thereto. For those skilled in the art, it is entirely possible to connect one or more adjustable constant current source circuits 20 in parallel to any one or more dynodes that need to adjust the voltage divider relationship according to the needs of actual applications, and these circuits can essentially be regarded as the realization of current mirrors.

[0084] In other words, no matter between which pair of dynodes the adjustable constant current source circuit 20 is connected in parallel, or the adjustable constant current source circuit 20 is connected in parallel on multiple pairs of dynodes at the same time, these changes and extensions should be regarded as valid implementation methods of the present invention and fall within the protection scope of the present invention.

[0085] Figure 8 is a schematic structural diagram of a voltage divider circuit according to another embodiment of the present invention, such as Figure 8 As shown, the first half of the voltage divider circuit is Figure 4 The first half of the voltage divider circuit shown is the same, and the second half of the voltage divider circuit mainly includes resistors R8~R14, capacitors C2~C5, and transistors Q4~Q7. Among them, resistors R8~R14 are used for voltage division and current limiting to ensure that each dynode and transistor obtains appropriate voltage and current. Capacitors C2~C5 are used for filtering to reduce power supply noise and signal interference to ensure stable operation of the circuit. Transistors Q4~Q7 are used to stabilize the current passing through the dynode, thereby reducing nonlinear distortion caused by current fluctuations and improving the linearity of the voltage divider circuit.

[0086] Fig. 9 is a schematic structural diagram of a voltage divider circuit according to another embodiment of the present invention, such as Fig. 9 As shown, the voltage divider circuit uses Darlington tubes Q8 to Q11 composed of two transistors instead of Figure 8 The single transistors Q4~Q7 in the circuit increase the current amplification factor, so that when the current output of the photomultiplier tube is large, the base current of the transistor presents smaller fluctuations, stabilizes the voltage division relationship of the voltage division circuit, and ensures the linearity of the photomultiplier tube response.

[0087] In an optional embodiment, the adjustable resistor RT is a digital potentiometer.

[0088] The digital potentiometer can achieve precise adjustment of the resistance value, ensuring more accurate voltage distribution in the voltage divider circuit, thereby meeting the needs of the photomultiplier tube under different working conditions.

[0089] In some other optional embodiments, the adjustable resistor RT may also be a sliding resistor.

[0090] Manual adjustment of the sliding rheostat is simple and intuitive. Users can change the resistance value by sliding the contact without complicated programming or remote control. This makes the sliding rheostat more advantageous in situations where quick adjustment or on-site operation is required.

[0091] Fig.10 is a schematic structural diagram of a digital potentiometer according to an embodiment of the present invention, such as Fig.10 As shown, the digital potentiometer includes a pin part and a functional module part.

[0092] The pin part includes the main power pin VDD, the logic power pin VLOGIC and the command interface SDA / SCL. Among them, the main power pin VDD is the pin that provides the main working power for the internal circuit of the digital potentiometer and is connected to an external positive voltage source. The logic power pin VLOGIC provides a specific working voltage for the logic circuit part inside the digital potentiometer. The command interface SDA / SCL is the interface for the digital potentiometer to communicate with an external controller (such as a microcontroller). SDA is a serial data line (Serial Data Line) used to transmit data, and SCL is a serial clock line (Serial Clock Line), which provides a synchronous clock signal to ensure that data can be accurately transmitted on the SDA line in a certain rhythm and sequence, so that the communication between the digital potentiometer and the external controller is carried out in an orderly manner.

[0093] The functional modules include power-on reset, I 2 C serial interface (I2CSERIALINTERFACE), electrically erasable programmable read-only memory (EEPROM) and resistance control register (RDAC-REGISTER).

[0094] In the figure, A is a fixed end point of the potentiometer resistance, B is another fixed end point of the potentiometer resistance, and W is the sliding end of the potentiometer. By changing the resistance setting of the digital potentiometer, that is, changing the position of W relative to A and B, the resistance can be adjusted.

[0095] The adjustable constant current source circuit 20 further includes a power supply circuit 210. Fig.11 is a schematic circuit diagram of a power supply circuit 210 according to an embodiment of the present invention, Fig.11 As shown, the power supply circuit 210 includes a first voltage stabilizing diode Z1, a first current limiting resistor R F1 , the second voltage stabilizing diode Z2 and the second current limiting resistor R F2 .

[0096] The anode terminal of the first voltage-stabilizing diode Z1 is connected to the first terminal of the voltage-dividing resistor 10, and the first current-limiting resistor R F1 The first end of the first voltage-stabilizing diode Z1 is connected to the cathode end of the first voltage-stabilizing diode Z1, and the second end is connected to the second end of the voltage-dividing resistor 10. The anode end of the second voltage-stabilizing diode Z2 is connected to the first end of the voltage-dividing resistor 10, and the second current-limiting resistor R F2 The first end is connected to the cathode end of the second voltage stabilizing diode Z2 , and the second end is connected to the second end of the voltage dividing resistor 10 .

[0097] A main power supply pin VDD of the digital potentiometer is connected to the cathode terminal of the first voltage zener diode Z1 , and a logic power supply pin VLOGIC is connected to the cathode terminal of the second voltage zener diode Z2 .

[0098] By using a voltage-stabilizing diode and a current-limiting resistor, the power supply circuit 210 can provide a stable main power supply and logic power supply voltage for the digital potentiometer, thereby ensuring the normal operation of the digital potentiometer and improving the accuracy and reliability of its output.

[0099] The existence of the current limiting resistor can prevent excessive current from flowing through the voltage-regulating diode, thereby protecting the voltage-regulating diode from damage, thereby improving the reliability and service life of the entire power supply circuit 210.

[0100] In addition, a stable power supply voltage helps the adjustable constant current source circuit 20 to maintain a constant output current. Since fluctuations in the power supply voltage can affect the output current of the constant current source, by stabilizing the power supply voltage, the performance of the constant current source can be improved to ensure that it can provide a stable current when the load changes.

[0101] The adjustable constant current source circuit 20 may further include a control subcircuit 220 , which is connected to the command interface SDA / SCL of the digital potentiometer and is configured to send a resistance adjustment command to the digital potentiometer.

[0102] Through the integrated control subcircuit 220, resistance adjustment instructions can be sent to the digital potentiometer in real time, so that the voltage division relationship of the voltage division circuit can be adjusted instantly and flexibly, giving the photomultiplier tube the ability to quickly adapt to various working environments and signal strengths.

[0103] In an optional embodiment, the control subcircuit 220 includes a controller MCU and an isolation device, wherein the controller MCU is used to output resistance adjustment instructions, the input side of the isolation device is connected to the controller MCU, and the output side of the isolation device is connected to the instruction interface SDA / SCL of the digital potentiometer, and is configured to perform signal isolation on the resistance adjustment instructions.

[0104] The introduction of isolation devices realizes electrical isolation between the controller MCU and the digital potentiometer. This isolation can effectively prevent safety hazards such as short circuit and overcurrent caused by failure of the controller MCU or digital potentiometer, thereby protecting the stable operation of the entire circuit system.

[0105] The isolation device can isolate and transmit the resistance adjustment command signal, reducing the attenuation and interference of the signal during the transmission process. This can ensure that the resistance adjustment command issued by the controller MCU can reach the digital potentiometer accurately, thereby improving the signal transmission reliability of the entire circuit system.

[0106] Fig.12 is a schematic circuit diagram of a control subcircuit 220 according to an embodiment of the present invention, such as Fig.12 As shown, the isolation device shown is a photoelectric isolator. The photoelectric isolator transmits information through optical signals to achieve electrical isolation between the input and output circuits. The photoelectric isolator includes a light emitting diode and a phototransistor. The input digital level signal (such as high level and low level) is converted into an optical signal through the internal light emitting diode and phototransistor, and then converted into a digital level signal at the output end. Since the photoelectric isolator can isolate faults, when a fault occurs in the circuit on the isolated side (such as short circuit, overvoltage, etc.), it will not affect the normal operation of the circuit on the other side.

[0107] Furthermore, a resistor R15 can be connected in series between the phototransistor and the logic power supply pin VLOGIC, and a resistor R16 can be connected in series between the light emitting diode and the controller MCU. The series resistor R15 can play a role in current limiting. For example, when the light intensity suddenly increases or the logic power supply voltage VLOGIC fluctuates, by limiting the current, it is possible to prevent excessive current from passing through the phototransistor, thereby extending the service life of the phototransistor and improving the reliability of the entire circuit. The series resistor R16 can calculate the appropriate current according to Ohm's law, limit the current passing through the light emitting diode within a safe range, and ensure the normal operation and service life of the light emitting diode.

[0108] Fig.13 is a schematic circuit diagram of a control subcircuit 220 according to another embodiment of the present invention. Fig.13 As shown, the isolation device shown is an isolation transformer. The isolation transformer realizes electrical isolation of the input and output circuits through the principle of electromagnetic induction. The isolation transformer includes a primary coil and a secondary coil, and there is no direct electrical connection between the primary coil and the secondary coil, which effectively prevents the transmission of DC current and low-frequency interference signals between the two circuits.

[0109] Furthermore, a resistor R15 may be connected in series between the secondary coil and the logic power supply pin VLOGIC. The resistor R15 can control the current passing through it to prevent excessive current from damaging the logic power supply pin VLOGIC and the logic circuit connected thereto.

[0110] At this point, those skilled in the art should recognize that, although multiple exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications that conform to the principles of the present invention can still be directly determined or derived based on the content disclosed in the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and recognized as covering all these other variations or modifications.

Claims

1. A voltage divider circuit for a photomultiplier tube, comprising: A plurality of voltage divider units are connected in series in sequence, and a connection point of two adjacent voltage divider units is used to connect a dynode of the photomultiplier tube, and at least part of the voltage divider units are configured as adjustable units, and each of the adjustable units comprises: Voltage divider resistors; and The adjustable constant current source circuit is connected in parallel with the voltage dividing resistor and is configured so that its own current size is controllable and adjustable, thereby changing the current proportion flowing through the voltage dividing resistor in the total current flowing through the adjustable unit, thereby adjusting the voltage across the voltage dividing resistor.

2. The voltage divider circuit for a photomultiplier tube according to claim 1, wherein: The adjustable constant current source circuit comprises: an adjustable resistor, a first end of which is connected to the first end of the voltage dividing resistor; A first transistor, a first end of which is connected to the second end of the adjustable resistor, and a third end of which is connected to the second end of the voltage-dividing resistor; a second transistor, a first end of which is connected to the first end of the adjustable resistor, and a second end of which is connected to the second end of the first transistor; and A first resistor has a first end connected to the second end and the third end of the second transistor respectively, and a second end connected to the second end of the voltage dividing resistor.

3. The voltage divider circuit for a photomultiplier tube according to claim 2, wherein: The first transistor and the second transistor are both NPN transistors, the first end of each NPN transistor is an emitter, the second end is a base, and the third end is a collector; or The first transistor and the second transistor are both PNP transistors, the first end of each PNP transistor is a collector, the second end is a base, and the third end is an emitter; or The first transistor and the second transistor are both NMOS transistors or both PMOS transistors, and the first end of each NMOS transistor or PMOS transistor is a source, the second end is a gate, and the third end is a drain.

4. The voltage divider circuit for a photomultiplier tube according to claim 2, wherein: The adjustable constant current source circuit also includes: a third transistor, a first terminal of which is connected to the second terminal of the second transistor, and a third terminal of which is connected to the second terminal of the voltage-dividing resistor; Furthermore, the first end of the first resistor is adjusted to be connected to the third end of the second transistor and the second end of the third transistor respectively.

5. The voltage divider circuit for a photomultiplier tube according to claim 4, wherein: The third transistor is an NPN transistor, the first end of the NPN transistor is an emitter, the second end is a base, and the third end is a collector; or The third transistor is a PNP transistor, the first end of the PNP transistor is a collector, the second end is a base, and the third end is an emitter; or The third transistor is an NMOS transistor or a PMOS transistor, the first end of the NMOS transistor or the PMOS transistor is a source, the second end is a gate, and the third end is a drain.

6. The voltage divider circuit for a photomultiplier tube according to claim 2, wherein: The adjustable constant current source circuit also includes: A fuse has a first end connected to the first end of the adjustable resistor and a second end connected to the emitter of the second transistor.

7. The voltage divider circuit for a photomultiplier tube according to claim 2, wherein: The adjustable resistor is a digital potentiometer, and the adjustable constant current source circuit further includes: The control subcircuit is connected to the instruction interface of the digital potentiometer and is configured to send a resistance adjustment instruction to the digital potentiometer.

8. The voltage divider circuit for a photomultiplier tube according to claim 7, wherein: The control subcircuit comprises: A controller, configured to output the resistance adjustment instruction; and The isolation device has an input side connected to the controller and an output side connected to the instruction interface of the digital potentiometer, and is configured to perform signal isolation on the resistance adjustment instruction.

9. The voltage divider circuit for a photomultiplier tube according to claim 8, wherein: The isolation device is a photoelectric isolator or an isolation transformer.

10. The voltage divider circuit for a photomultiplier tube according to claim 7, wherein: The digital potentiometer has a main power supply pin and a logic power supply pin, and the adjustable constant current source circuit also includes a power supply circuit, which includes: A first voltage stabilizing diode, an anode terminal of which is connected to the first end of the voltage dividing resistor; A first current limiting resistor, a first end of which is connected to the cathode end of the first voltage stabilizing diode, and a second end of which is connected to the second end of the voltage dividing resistor; A second voltage stabilizing diode, an anode terminal of which is connected to the first end of the voltage dividing resistor; and A second current limiting resistor, a first end of which is connected to the cathode end of the second voltage stabilizing diode, and a second end of which is connected to the second end of the voltage dividing resistor; The main power supply pin of the digital potentiometer is connected to the cathode terminal of the first Zener diode, and the logic power supply pin is connected to the cathode terminal of the second Zener diode.

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