CN219935073U - Electromagnetic force driving circuit of electronic balance - Google Patents
Electromagnetic force driving circuit of electronic balance Download PDFInfo
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- CN219935073U CN219935073U CN202320327781.XU CN202320327781U CN219935073U CN 219935073 U CN219935073 U CN 219935073U CN 202320327781 U CN202320327781 U CN 202320327781U CN 219935073 U CN219935073 U CN 219935073U
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- 238000006243 chemical reaction Methods 0.000 claims abstract description 11
- 238000012545 processing Methods 0.000 claims abstract description 11
- 230000003321 amplification Effects 0.000 claims abstract description 6
- 238000003199 nucleic acid amplification method Methods 0.000 claims abstract description 6
- 238000005259 measurement Methods 0.000 abstract description 10
- 230000002457 bidirectional effect Effects 0.000 abstract description 4
- 230000006872 improvement Effects 0.000 description 5
- 230000000295 complement effect Effects 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 230000008859 change Effects 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000013480 data collection Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
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- 238000010586 diagram Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
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Abstract
The utility model discloses an electromagnetic force driving circuit of an electronic balance, which comprises a signal input processing circuit, a unidirectional signal conversion circuit, a current coil and an AD converter, wherein the signal input processing circuit is connected with the unidirectional signal conversion circuit; the signal input processing circuit comprises an operational amplifier U1B and a first power compensation circuit, the signal input processing circuit is used for voltage following and power amplification, the reverse input end and the output end of the operational amplifier U1B are connected with the first power compensation circuit, and the first power compensation circuit is connected with a current coil; the unidirectional signal conversion circuit comprises an operational amplifier U1A and a second power compensation circuit. Compared with the prior art, the utility model has the advantages that: the bidirectional force measuring structure can realize high-precision measurement and increase the measurement range.
Description
Technical Field
The utility model relates to the technical field of electronic metering, in particular to an electromagnetic force driving circuit of an electronic balance.
Background
An electronic balance is a measuring instrument for measuring the weight of a measured object by means of electromagnetic force and weight balance of the measured object. The basic principle is lever balance principle, which is equivalent to original mechanical balance. But the electronic balance changes the proportioning weight structure at one end of the original mechanical balance into an electromagnetic force structure, then adjusts the proportion of the lever, reduces the original clumsy mechanical balance, performs attractive packaging and directly obtains readable weight data. The electromagnetic force is composed of circuit control, permanent magnet, current coil, magnetic yoke, etc., the electromagnetic force is calculated by basic ampere force F=BLI, and physical quantity B and L in the electronic balance are constant, so the weight of the measured substance can be obtained by controlling and measuring current I through the circuit structure.
Most of electronic balances in the current market adopt a unidirectional force measuring structure, so that the circuit is simple to control and easy to design and manufacture. The unidirectional force measuring structure is characterized in that the stress of an electrified coil in a permanent magnet is always vertical and downward, and the current direction in the coil is always in a single direction. When the measured object is placed on the scale pan of the balance, the current in the coil is increased, so that the electromagnetic force is increased, the balance state is achieved, and the weight of the measured object is converted.
The unidirectional force measurement control is difficult to achieve high-precision and large-scale measurement. The mechanical structure of the electronic balance has a self-weight of the coil structure, and an appropriate weight must be placed at the other end of the fulcrum, i.e., the end where the object to be measured is placed, to neutralize the self-weight. If an electronic balance with a large range is to be achieved, the lever proportion must be increased, but the proportion is increased, the weight force must be increased when balancing out the weight force, and the weight force is increased at two ends of the fulcrum, so that the inertia at two ends of the fulcrum is increased.
Disclosure of Invention
The technical problem to be solved by the utility model is to overcome the defects and provide an electromagnetic force driving circuit of an electronic balance.
In order to solve the technical problems, the technical scheme provided by the utility model is as follows: an electromagnetic force driving circuit of an electronic balance comprises a signal input processing circuit, a unidirectional signal conversion circuit, a current coil and an AD converter;
the signal input processing circuit comprises an operational amplifier U1B and a first power compensation circuit, the signal input processing circuit is used for voltage following and power amplification, the reverse input end and the output end of the operational amplifier U1B are connected with the first power compensation circuit, and the first power compensation circuit is connected with a current coil;
the unidirectional signal conversion circuit comprises an operational amplifier U1A and a second power compensation circuit, the unidirectional signal conversion circuit is used for maintaining constant potential points and power amplification, the reverse output end and the output end of the operational amplifier U1A are connected with the second power compensation circuit, the current coil is connected with the reverse input end and the second power compensation circuit of the operational amplifier U1A, and the second power compensation circuit is connected with the AD converter.
As an improvement, the same-directional input end of the operational amplifier U1B is connected with the set voltage signal input end Vin.
As an improvement, the first power compensation circuit includes a transistor Q2, a transistor Q5, a resistor R12, a first analog power VCC and a first negative power VEE, where an inverting input terminal of the operational amplifier U1B is connected to one end of the resistor R12, an emitter of the transistor Q2, and an emitter of the transistor Q5, another end of the resistor R12 is connected to an output terminal of the operational amplifier U1B, a base of the transistor Q2, and a base of the transistor Q5, one end of the current coil is connected to the resistor R12, the inverting input terminal of the operational amplifier U1B, the emitter of the transistor Q2, and the emitter of the transistor Q5, a collector of the transistor Q2 is connected to the first analog power VCC, and a collector of the transistor Q5 is connected to the first negative power.
As an improvement, the unidirectional input end of the operational amplifier U1A is respectively connected with a resistor R28 and a resistor R39, the other end of the resistor R28 is connected with a reference voltage Vref, and the other end of the resistor R39 is grounded.
As an improvement, the upper pin and the lower pin of the operational amplifier U1A are respectively connected with a second analog power supply VCC and a second negative power supply VEE.
As an improvement, the second power compensation circuit comprises a PNP transistor Q6, a transistor Q7, a resistor R25, a resistor R27 and a third analog power supply VCC, one end of the resistor R25 is connected with the current coil and the inverting input end of the operational amplifier U1A, the other end of the resistor R25 is connected with one end of the resistor R27, the emitter of the PNP transistor Q6, the emitter of the transistor Q7 and the AD converter, the other end of the resistor R27 is connected with the output end of the operational amplifier U1A, the base of the PNP transistor Q6 and the base of the transistor Q7, the collector of the PNP transistor Q6 is grounded, and the collector of the transistor Q7 is connected with the third analog power supply VCC.
Compared with the prior art, the utility model has the advantages that: the bidirectional force measuring structure can realize high-precision measurement and increase the measurement range.
In the unidirectional force measurement control structure, an energized coil in the electromagnetic force is always subjected to downward electromagnetic force, the current in the coil cannot be changed, and if the circuit is designed to change the direction of the current, the force in two directions can be formed. The force acting vertically upwards is increased, the self weight of a coil mechanical structure and the like is lifted to reach balance under the no-load state of the balance, the coil current is reduced when the weight is added at one end of the scale pan, the reduction is equivalent to the added weight, and therefore the measuring range of the electronic balance is increased.
However, the direction of current changes in the coil, a negative voltage signal appears when the circuit signal is collected, and the AD conversion chip responsible for data collection can only collect a unidirectional signal under unidirectional voltage control, so that the circuit control needs to be designed into a bidirectional current control and unidirectional signal output mode.
Drawings
Fig. 1 is a circuit diagram of an electromagnetic force driving circuit of an electronic balance according to the present utility model.
Detailed Description
The present utility model will be described in further detail with reference to the accompanying drawings.
With reference to fig. 1, the circuit structure mainly comprises an operational amplifier, a transistor, a resistor, an AD converter, a current coil and a permanent magnet. The current is changed in the positive direction and the negative direction, and the independent forward voltage signal is transmitted to the AD converter to work, so that the measurement and unidirectional data signal acquisition work by utilizing the self weight of the mechanical structure is realized.
The circuit structure mainly comprises two parts, wherein the first part is a signal input processing circuit, the second part is a unidirectional signal conversion circuit, and the tail ends of the two circuits are both composed of power complementary circuits, so that the driving capability of the circuit is improved.
The operational amplifier U1B and the power compensation circuit are the first parts, play a role in voltage following and power amplification, increase the input impedance of a signal input signal, reduce the loss of the signal, play a role in protecting the signal and improve the measurement accuracy of an electronic balance. The voltage follower post-change is a power complementary circuit formed by two transistors and related resistors, the driving capability of the current coil is improved, and positive and negative voltage sets are adopted at two ends of the power complementary circuit, so that the change of the current direction is achieved, and one current is a first analog power supply VCC-transistor Q2-power coil-resistor R12-transistor Q6-ground (defined as the current positive direction); the other path is composed of a third analog power supply VCC-a transistor Q7-a resistor R25-a coil current-a transistor Q5-a first negative power supply VEE (defined as a current negative direction).
The operational amplifier U1A and the power complementary circuit have the functions of maintaining a constant potential point and amplifying power, the potential of the V2 point is clamped at a proper potential point, the AD converter is guaranteed to be forward when receiving the minimum signal input, the bidirectional current driving electromagnetic force is achieved, and the purpose of the unidirectional AD signal acquisition circuit is achieved.
Vref is the reference voltage input to keep constant, V3 potential is obtained after voltage division through a resistor R28 and a resistor R39, and V2 = V3 is obtained according to the 'virtual short' action between V2 and V3 of the working principle of the operational amplifier; the resistor R25 bit signal in the illustration samples the resistor, thus resulting in a current in the coil of: i= (Vout-V2)/R25; wherein V2 is constant, so that the voltage signal measured by the AD converter is equivalent to the current signal flowing through the coil, and the electromagnetic force f=bil, wherein B and L are also constant constants, so that the magnitude of the current I is equivalent to the magnitude of the weight of the object to be measured.
The circuit process of the electronic balance in the working process is briefly described as follows:
in the balance empty load state, the signal detected by the AD converter is minimum, and is in the minimum measurement state, at the moment, the current direction is positive, the Vout potential is the lowest, the voltage at two ends of the resistor R25 is larger, the electromagnetic force received in the coil is also larger, the electromagnetic force at the moment is mainly used for balancing the dead weight of a balance mechanical system, when a weight is loaded on an electronic balance weighing disc, the potential signal of the voltage signal input end Vin is gradually reduced, the current in the coil is also reduced, the electromagnetic force is reduced, and the reduced electromagnetic force is equivalent to the loaded corresponding weight. When the weight is loaded to a certain extent, the current in the coil is 0, vout=v2, at the moment, the weight to be measured and the dead weight of the machine counteract each other, if the weight is continuously loaded, vout is gradually larger than V2, the current can become negative direction to flow, and the electromagnetic force can continuously and gradually increase. In the whole process, the electromagnetic force is firstly in an upward direction, zero direction and then downward direction. The electronic balance completes a loading process from no load to full load.
The utility model and its embodiments have been described above with no limitation, and the actual construction is not limited to the embodiments of the utility model as shown in the drawings. In summary, if one of ordinary skill in the art is informed by this disclosure, a structural manner and an embodiment similar to the technical solution should not be creatively devised without departing from the gist of the present utility model.
Claims (6)
1. An electromagnetic force driving circuit of an electronic balance is characterized in that: the device comprises a signal input processing circuit, a unidirectional signal conversion circuit, a current coil and an AD converter;
the signal input processing circuit comprises an operational amplifier U1B and a first power compensation circuit, the signal input processing circuit is used for voltage following and power amplification, the reverse input end and the output end of the operational amplifier U1B are connected with the first power compensation circuit, and the first power compensation circuit is connected with a current coil;
the unidirectional signal conversion circuit comprises an operational amplifier U1A and a second power compensation circuit, the unidirectional signal conversion circuit is used for maintaining constant potential points and power amplification, the reverse output end and the output end of the operational amplifier U1A are connected with the second power compensation circuit, the current coil is connected with the reverse input end and the second power compensation circuit of the operational amplifier U1A, and the second power compensation circuit is connected with the AD converter.
2. An electronic balance electromagnetic force driving circuit according to claim 1, wherein: the homodromous input end of the operational amplifier U1B is connected with the set voltage signal input end Vin.
3. An electronic balance electromagnetic force driving circuit according to claim 1, wherein: the first power compensation circuit comprises a transistor Q2, a transistor Q5, a resistor R12, a first analog power supply VCC and a first negative power supply VEE, wherein the reverse input end of the operational amplifier U1B is connected with one end of the resistor R12, the emitter of the transistor Q2 and the emitter of the transistor Q5, the other end of the resistor R12 is respectively connected with the output end of the operational amplifier U1B, the base of the transistor Q2 and the base of the transistor Q5, one end of the current coil is connected with the resistor R12, the reverse input end of the operational amplifier U1B, the emitter of the transistor Q2 and the emitter of the transistor Q5, the collector of the transistor Q2 is connected with the first analog power supply VCC, and the collector of the transistor Q5 is connected with the first negative power supply.
4. An electronic balance electromagnetic force driving circuit according to claim 1, wherein: the unidirectional input end of the operational amplifier U1A is respectively connected with a resistor R28 and a resistor R39, the other end of the resistor R28 is connected with a reference voltage Vref, and the other end of the resistor R39 is grounded.
5. An electronic balance electromagnetic force driving circuit according to claim 1, wherein: the upper pin and the lower pin of the operational amplifier U1A are respectively connected with a second analog power supply VCC and a second negative power supply VEE.
6. An electronic balance electromagnetic force driving circuit according to claim 1, wherein: the second power compensation circuit comprises a PNP (plug and play) transistor Q6, a transistor Q7, a resistor R25, a resistor R27 and a third analog power supply VCC, wherein one end of the resistor R25 is respectively connected with a current coil and an inverting input end of an operational amplifier U1A, the other end of the resistor R25 is respectively connected with one end of the resistor R27, an emitter of the PNP transistor Q6, an emitter of the transistor Q7 and an AD (analog-to-digital) converter, the other end of the resistor R27 is respectively connected with an output end of the operational amplifier U1A, a base of the PNP transistor Q6 and a base of the transistor Q7, a collector of the PNP transistor Q6 is grounded, and a collector of the transistor Q7 is connected with the third analog power supply VCC.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320327781.XU CN219935073U (en) | 2023-02-28 | 2023-02-28 | Electromagnetic force driving circuit of electronic balance |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320327781.XU CN219935073U (en) | 2023-02-28 | 2023-02-28 | Electromagnetic force driving circuit of electronic balance |
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| Publication Number | Publication Date |
|---|---|
| CN219935073U true CN219935073U (en) | 2023-10-31 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202320327781.XU Active CN219935073U (en) | 2023-02-28 | 2023-02-28 | Electromagnetic force driving circuit of electronic balance |
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| Country | Link |
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| CN (1) | CN219935073U (en) |
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- 2023-02-28 CN CN202320327781.XU patent/CN219935073U/en active Active
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