A transistor temperature compensation circuit

Abstract

The present invention discloses a triode temperature compensation circuit, comprising an operational amplifier U1, a Vref-Z adjustment circuit, a transistor circuit, and a Vref-F adjustment circuit. The operational amplifier U1 is used for voltage following and increasing output impedance, thus acting as a voltage divider. The transistor circuit is used to obtain resistance values of V1 and V2 that match the temperature characteristics of the calculation balance. The transistor circuit is connected to the Vref-Z adjustment circuit and the Vref-F adjustment circuit. The Vref-Z adjustment circuit and the Vref-F adjustment circuit are used to perform temperature compensation for zero-point drift error and full-scale drift error. The advantages of the present invention over the prior art are: stable performance, low cost, and easy debugging; temperature compensation of the product is achieved by processing the voltage. This compensation method does not interfere with the weak analog signal of the sensor and does not consume CPU resources.

Description

Technical Field

[0001] The invention relates to the technical field of electronic balance temperature compensation, in particular to a triode temperature compensation circuit. Background Art

[0002] Any sensor will experience temperature drift errors as temperature changes. Electronic balances, a high-precision mass and mechanical measurement product based on electromagnetic force sensors, naturally also experience errors due to temperature fluctuations. This error must be corrected through technical means, and there are many methods for doing so. Currently, some methods include software compensation and using temperature sensors to collect temperature. These methods then use the relationship between temperature changes and balance error data to form a correction function to obtain accurate data. However, these methods are difficult to implement in high-precision balances, as the sensor's inherent accuracy can interfere with the balance's stability and are relatively costly. Other methods utilize the temperature characteristics of resistors to neutralize the temperature characteristics of the balance, achieved through software or hardware techniques. However, the thermal noise of resistors can also interfere with high-precision balances. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the above-mentioned defects and provide a transistor temperature compensation circuit.

[0004] To solve the above technical problems, the present invention provides a technical solution as follows: a transistor temperature compensation circuit, comprising an operational amplifier U1, a Vref-Z adjustment circuit, a transistor circuit and a Vref-F adjustment circuit;

[0005] The operational amplifier U1 is used for voltage following and increasing output impedance, and plays a role of voltage division. The operational amplifier U1 is connected to the Vref-Z adjustment circuit;

[0006] The transistor circuit is used to obtain resistance values that match the temperature characteristics of V1 and V2 computing balances. The transistor circuit includes a reference voltage Vref, a resistor R1, a transistor Q1, and a resistor R10. The reference voltage Vref is connected to one end of the resistor R1, the other end of the resistor R1 is connected to the collector of the transistor Q1, the base of the transistor Q1 is connected to the collector of the transistor Q1, the emitter of the transistor Q1 is connected to the resistor R10, and the other end of the resistor R10 is grounded. The transistor circuit is connected to a Vref-Z adjustment circuit and a Vref-F adjustment circuit;

[0007] The Vref-Z adjustment circuit and the Vref-F adjustment circuit are used to complete the temperature compensation function of the zero drift error and the full drift error, and the Vref-Z adjustment circuit and the Vref-F adjustment circuit are connected to each other.

[0008] As an improvement, the Vref-Z adjustment circuit includes a resistor R2, a sliding resistor R4, a resistor R7, a resistor R6, a resistor R9, a capacitor C1 and a capacitor C3. One end of the resistor R2 is connected to the resistor R1 and the collector of the transistor Q1, the other end of the resistor R2 is connected to one end of the sliding resistor R4, the other end of the sliding resistor R4 is connected to the resistor R7, and the sliding end of the sliding resistor R4 is connected to the reverse input end of the operational amplifier U1 and one end of the capacitor C1.

[0009] As an improvement, the other end of the capacitor C1 is connected to the capacitor C3, the resistor R9 and the resistor R10, the other end of the capacitor C3 is connected to the resistor R6 and the resistor R9, one end of the resistor R6 is connected to the same-direction input and output of the operational amplifier U1, and the other end of the resistor R6 is connected to the resistor R9.

[0010] As an improvement, the Vref-F adjustment circuit includes a resistor R3, a resistor R5, a sliding resistor R8 and a capacitor C2, one end of the resistor R3 is connected to the resistor R1, the resistor R2 and the collector of the transistor Q1, the other end of the R3 is connected to the resistor R5 and the capacitor C2, the other end of the resistor R5 is connected to one end of the sliding resistor R8, the other end of the sliding resistor R8 is connected to its sliding end, the resistor R7, the resistor R10 and the emitter of the transistor Q1, and the other end of the C2 is connected to the resistor R9, the resistor R10, the capacitor C1 and the capacitor C3.

[0011] As an improvement, V1 and V2 at both ends of the transistor Q1 change with the ambient temperature.

[0012] The advantages of this invention over existing technologies include stable performance, low cost, and easy debugging. It utilizes PNP transistors and exploits the characteristics of the transistor's PN junction, which linearly decreases the voltage across the junction as temperature rises within the product's application temperature range. Resistors are connected in parallel across the PN junction, generating a voltage output between the resistor nodes. This output voltage exhibits a functional relationship with the voltage at the PN junction's input. The output voltage is stable and reliable, virtually unaffected by interference from other attached electronic components. This voltage curve is then generated, resulting in a voltage curve that correlates with the temperature curve. By processing this voltage, temperature compensation for the product is achieved. This compensation method does not interfere with the sensor's weak analog signal and does not consume CPU resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The present invention discloses a temperature compensation circuit diagram of a triode temperature compensation circuit.

[0014] Figure 2 The present invention is a circuit diagram of an electronic balance electronic circuit with a triode temperature compensation circuit. DETAILED DESCRIPTION

[0015] The present invention will be described in further detail below with reference to the accompanying drawings.

[0016] Combined with attachment Figure 2 In the present invention, Vref-F is the full-scale reference voltage, Vref-Z is the zero-point reference voltage of the negative signal input terminal of the AD converter, and a 24-bit AD analog-to-digital conversion chip is used, which has an analog signal positive input terminal, an analog signal negative input terminal and a reference voltage input terminal. The other pins of the chip are power supply and signal input terminals; the AD analog-to-digital conversion chip is responsible for resolving the difference between the positive input value (V+) and the negative input value (Vrev-Z) of the analog signal into a digital signal and providing it to the CPU for calculation and processing.

[0017] Attachment Figure 2 The higher the Vref-F reference voltage is, the smaller the digital value obtained by the converter from the same analog signal input at the input end is. Taking the 24-bit AD converter of the present invention as an example, the final result output by the AD converter is: From the formula, we can see that Vref-F will affect the gain component of the sensor, that is, the sensitivity drift of the electronic balance; Vref-Z affects the zero component of the sensor, that is, the zero drift of the electronic balance.

[0018] Combined with attachment Figure 1 The reference voltage Vref remains constant, while the voltages V1 and V2 across transistor Q1 change when the ambient temperature changes. The voltage across transistor Q1 gradually decreases as the temperature rises. The total current in the circuit increases. Assuming the voltage across transistor Q1 is V12, the current in the circuit is I = (Vref - V12) / (R1 + R10); thus, the total current increases. Therefore, V1 decreases, while V2 increases, and vice versa. By adjusting variable resistors R8 and R4, Vref-F and Vref-Z also change with temperature.

[0019] The following formula is derived from the above circuit principle description:

[0020]

[0021] The resistance of R8 is variable and is adjusted to match the temperature characteristics of the balance through temperature testing;

[0022]

[0023] R4 is a variable resistance value, adjusted through temperature testing to match the balance's temperature characteristics. R4' is the component resistance of R4. In the above formula, all resistors except R8 and R4 serve as current-limiting or voltage-divider resistors. The op amp in the figure acts as a voltage follower and increases output impedance, preventing the Vref-Z terminal load from affecting V1 and V2. It also acts as a voltage divider.

[0024] When making adjustments, first set a low-temperature process, such as a 10°C environment. After the ambient temperature is balanced, record the displayed value when the balance is not loaded with weight materials, then record a weight loaded with the maximum range and record the displayed value; then set a high-temperature process, such as 40°C. After the ambient temperature stabilizes, record the above two values of the balance again.

[0025] Calculate the difference between the balance display values when the balance is unloaded in two temperature environments. This value is called the zero drift error. This value is related to the amplitude of Vref-Z changes with temperature. By adjusting the sliding resistor R4, the amplitude of Vref-Z change can be adjusted. Through repeated trials and adjustments, the amplitude of Vref-Z change is finally adjusted to be consistent with the amplitude of balance display change. In this way, the visual result of the balance is 0 when the temperature changes, achieving the zero point temperature compensation effect of the balance.

[0026] Similarly, the difference between the full-load balance indications in the two temperature environments is calculated. This value is called the full-scale drift error. This value has a temperature ratio relationship with Vref-F. The sliding resistor R8 is adjusted in the same way as the sliding resistor R4, and finally the full-load balance indication is the same in different temperature environments, thus achieving the effect of temperature compensation.

[0027] The present invention and its embodiments are described above. This description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. In short, if a person skilled in the art is inspired by this and, without departing from the purpose of the present invention, designs structures and embodiments similar to this technical solution without inventiveness, they shall fall within the scope of protection of the present invention.

Claims

1. A transistor temperature compensation circuit, characterized in that: It includes an operational amplifier U1, a Vref-Z adjustment circuit, a transistor circuit and a Vref-F adjustment circuit; The operational amplifier U1 is used for voltage following and increasing output impedance, and plays a role of voltage division. The operational amplifier U1 is connected to the Vref-Z adjustment circuit; The transistor circuit is used to obtain resistance values that match the temperature characteristics of V1 and V2 computing balances. The transistor circuit includes a reference voltage Vref, a resistor R1, a transistor Q1, and a resistor R10. The reference voltage Vref is connected to one end of the resistor R1, the other end of the resistor R1 is connected to the collector of the transistor Q1, the base of the transistor Q1 is connected to the collector of the transistor Q1, the emitter of the transistor Q1 is connected to the resistor R10, and the other end of the resistor R10 is grounded. The transistor circuit is connected to a Vref-Z adjustment circuit and a Vref-F adjustment circuit; The Vref-Z adjustment circuit and the Vref-F adjustment circuit are used to complete the temperature compensation function of the zero drift error and the full drift error, and the Vref-Z adjustment circuit and the Vref-F adjustment circuit are connected to each other; The Vref-Z adjustment circuit includes a resistor R2, a sliding resistor R4, a resistor R7, a resistor R6, a resistor R9, a capacitor C1 and a capacitor C3, wherein one end of the resistor R2 is connected to the resistor R1 and the collector of the transistor Q1, the other end of the resistor R2 is connected to one end of the sliding resistor R4, the other end of the sliding resistor R4 is connected to the resistor R7, and the sliding end of the sliding resistor R4 is connected to the inverting input end of the operational amplifier U1 and one end of the capacitor C1; The other end of the capacitor C1 is connected to the capacitor C3, the resistor R9 and the resistor R10, the other end of the capacitor C3 is connected to the resistor R6 and the resistor R9, one end of the resistor R6 is connected to the non-inverting input and output of the operational amplifier U1, and the other end of the resistor R6 is connected to the resistor R9; The Vref-F adjustment circuit includes a resistor R3, a resistor R5, a sliding resistor R8 and a capacitor C2. One end of the resistor R3 is connected to the resistor R1, the resistor R2 and the collector of the transistor Q1. The other end of the resistor R3 is connected to the resistor R5 and the capacitor C2. The other end of the resistor R5 is connected to one end of the sliding resistor R8. The other end of the sliding resistor R8 is connected to its sliding end, the resistor R7, the resistor R10 and the emitter of the transistor Q1. The other end of C2 is connected to the resistor R9, the resistor R10, the capacitor C1 and the capacitor C3.

2. The transistor temperature compensation circuit according to claim 1, wherein: V1 and V2 at both ends of the transistor Q1 change with the change of ambient temperature.

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