CN203534694U

CN203534694U - Remote-control digital weighing machine with temperature compensation function

Info

Publication number: CN203534694U
Application number: CN201320193462.0U
Authority: CN
Inventors: 唐令弟
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-04-17
Filing date: 2013-04-17
Publication date: 2014-04-09
Anticipated expiration: 2023-04-17

Abstract

The utility model relates to a remote-control digital weighing machine with a temperature compensation function. The remote-control digital weighing machine comprises a weighing sensor, an AD conversion module, a CPU, an external DSP display, an interface circuit, a temperature compensation circuit, an external voltage testing circuit, a keyboard circuit, a wireless communication module, a power supply and a DC-DC charge pump of a stabilized voltage power supply; an equal-arm bridge of the weighing sensor comprises four resistance strain gauges, and components are powered by the power supply and the DC-DC charge pump of the stabilized voltage power supply; after force signals detected by the weighing sensor are converted to analog electric signals, the analog electric signals are inputted to the AD conversion module and are converted into digital signals, and the digital signals are inputted to the CPU to be processed so that a weight value of a measured object is obtained; an output terminal of the CPU is respectively connected with the external DSP display and the interface circuit, an input terminal of the CPU is connected with the temperature compensation circuit, and the output terminal of the CPU is also connected with the wireless communication module; the power supply outputs two power supply channels via the DC-DC charge pump of the stabilized voltage supply, and the AD conversion module and the CPU are respectively powered by the two power supply channels. The remote-control digital weighing machine can be applicable to different usage occasions.

Description

The digital weighing apparatus of a kind of remote control temperature compensation

Technical field

The utility model relates to a kind of weighing apparatus, particularly about the digital weighing apparatus of a kind of remote control temperature compensation.

Background technology

At present, electronic scales is generally comprised of LOAD CELLS (comprising simulation LOAD CELLS or digital LOAD CELLS) and weighing instrument, between LOAD CELLS and weighing instrument, is separated from each other, and the power supply of LOAD CELLS is supplied with by weighing instrument.After LOAD CELLS is stressed, by circuit, faint signal is sent to secondary instrument and processes.The feeble signal of LOAD CELLS output has decay, and is easily subject to electromagnetic interference (EMI) in circuit transmitting procedure, and same secondary instrument also easily makes moist outside, is subject to the interference of electromagnetic field.Digital LOAD CELLS antijamming capability increases, but digital LOAD CELLS still must external instrument, and inside has CPU and software etc. just can complete the function of electronic scales.

And because LOAD CELLS is an accurate equal arm bridge, when stressed, be attached to the foil gauge resistance generation subtle change on elastic body, electric bridge out of trim, just there is output signal, the conventional 350 Europe sensors of take are example, foil gauge change in resistance 0.0001 Ω, will produce 1/3000 error, visible LOAD CELLS is so high to the stability requirement of foil gauge, when in fact sensor changes within the scope of-10 °～+ 40 °, can produce very large temperature zero drift, and be random, have just have negative, each temperature section drift value is inconsistent, be difficult to find that a hardware temperature compensation device can fine compensation within the scope of total temperature.In fact, according to the result of country's selective examination electronic scale sensor, temperature drift is underproof to occupy the majority.

In addition, the signal output of LOAD CELLS can be subject to the impact of temperature, so each LOAD CELLS will carry out hardware temperatures compensation through complicated technique, and requirement is just likely up to state standards.When some industrial electronic scales are used at the scene, need bracing wire to pulpit, reading can not be directly seen at existence scene, can not operate at scene the defects such as demarcation.

Summary of the invention

For the problems referred to above, the purpose of this utility model is to provide a kind of digital weighing apparatus of remote control temperature compensation that can effectively overcome electromagnetic interference (EMI), have temperature compensation function.

For achieving the above object, the utility model is taked following technical scheme: the digital weighing apparatus of a kind of remote control temperature compensation, it is characterized in that: it comprises LOAD CELLS, AD modular converter, CPU, external DSP display, interface circuit, temperature-compensation circuit, external voltage test circuit, keyboard circuit, the wireless communication module that consists of equal arm bridge four resistance strain gages, and be power supply and the stabilized voltage supply DC-DC charge pump of each parts power supply; Described LOAD CELLS is converted to the force signal detecting after analog electrical signal, inputs described AD modular converter analog electrical signal is converted to digital signal, and input the gravimetric value that obtains testee after processing in described CPU; The output terminal of described CPU connects described external DSP display and interface circuit, and the input end of described CPU connects described temperature-compensation circuit, and the output terminal of described CPU also connects described wireless communication module; Described power supply, by described stabilized voltage supply DC-DC charge pump output two-way power supply, is respectively described AD modular converter and CPU power supply.

In described CPU, be built-in with 8 tunnel AD converter, wherein three tunnels connect respectively described temperature-compensation circuit, external voltage test circuit and keyboard circuit; Described temperature-compensation circuit after described 8 tunnel AD converter, is inputted the operating ambient temperature value detecting in the storer in described CPU, to carry out temperature compensation; Described external voltage test circuit is for detection of the supply voltage of described power supply, and inputs the storer in described CPU after described 8 tunnel AD converter, detects described Power supply state; Described keyboard circuit is also inputted the storer in described CPU by the push button signalling of outside input after described 8 tunnel AD converter, by described keyboard circuit, the parameter of temperature zero drift and temperature span drift is inputed in described CPU storer; Thermistor temp-resistance the table of comparisons, temperature drift and the temperature span drift curve that by thermistor producer, are provided are also provided in the storer in described CPU.

Described temperature-compensation circuit comprises measuring resistance and as the pasted sheet type thermistor of temperature element, output signal after described measuring resistance and pasted sheet type thermistor series connection, after 8 tunnel AD converter in described CPU, input in described CPU storer, compare with the thermistor temp-resistance table of comparisons being preset in described CPU storer.

Described AD modular converter adopts 24 octal encapsulation conversion chip HX710, and be provided with in the surrounding of described AD modular converter paster LC element and the screen layer that absorbs electromagnetic interference (EMI), and adopting AD sampling and wireless receiving and dispatching timesharing partition method, described timesharing partition method adopts software second-order filter.

Described CPU adopts the chip of the high speed 1T TSSOP-20 microencapsulated of STC Corporation; Described external DSP display adopts LCD, LED, VFD or MCD display.

The utility model is owing to taking above technical scheme, it has the following advantages: 1, the utility model for example, is gone up and be encapsulated in LOAD CELLS because employing is integrated in a less circuit board (1.6 * 1.6cm double-sided printed-circuit board) by the major function of weighing instrument, do not have LOAD CELLS to be connected with the external cable between weighing instrument, there is no the decay of signal transmission, overcome electromagnetic interference (EMI).2, the utility model temperature-compensation circuit adopts paster thermistor as temperature element, and in the built-in 8 tunnel AD converter of CPU, wherein a road is detected the resistance of thermistor, by being preset at the temperature-resistance table of comparisons in CPU, adopt computation of table lookup to obtain the exact value of environment temperature, and by the curve of sensor temperature drift curve and temperature span drift, divide 10 warm areas, each warm area 6.4 degree, several Ju pieces of 640 temperature compensations altogether, according to the temperature recording, obtain temperature zero-bit and the temperature range offset that will compensate, revise the error causing due to temperature impact, reach the object of high-acruracy survey, and then the qualification rate of sensor is improved greatly.The utility model can be applied in different use occasions.

Accompanying drawing explanation

Fig. 1 is one-piece construction schematic diagram of the present utility model.

Embodiment

Below in conjunction with drawings and Examples, the utility model is described in detail.

As shown in Figure 1, the digital weighing apparatus of a kind of remote control temperature compensation that the utility model provides, is that weighing instrument is arranged on to (for example 1.6 * 1.6cm double-sided printed-circuit board) on a less double-sided printed-circuit board, and is packaged with various sensors.The utility model comprises LOAD CELLS 1, AD modular converter 2, microprocessor (CPU) 3, external DSP display 4, interface circuit 5, temperature-compensation circuit 6, external voltage test circuit 7, keyboard circuit 8, the wireless communication module 9 that consists of equal arm bridge four resistance strain gages, and is power supply 10 and the stabilized voltage supply DC-DC charge pump 11 of above-mentioned each parts power supply.

LOAD CELLS 1 is converted to the force signal detecting after analog electrical signal, and input AD modular converter 2 is converted to digital signal by analog electrical signal, and inputs the gravimetric value that obtains testee after processing in CPU3.The output terminal of CPU3 connects external DSP display 4 and interface circuit 5, can external other equipment by interface circuit 5, carry out connected network communication, and Jus transmit and man-machine conversation number.The input end of CPU3 connects temperature-compensation circuit 6, realizes the measuring-signal that CPU3 is received carry out temperature zero compensation and temperature span compensation by temperature-compensation circuit 6.The output terminal of CPU3 also connects wireless communication module 9, by wireless communication module 9, can realize multiple communication modes, sending function, receiving function or receipts/send out function for example, and can realize several data transmission form, can also arrange No. ID, realize multiple combined network communication function, show code can be set, without external-connection displayer, can on PC, directly show data and function.

In above-described embodiment, the utility model adopts and in CPU3, is built-in with 8 tunnel AD converter (not shown)s, and wherein three tunnels are respectively used to connect temperature-compensation circuit 6, external voltage test circuit 7 and keyboard circuit 8.Temperature-compensation circuit 6 after 8 tunnel AD converter, in the storer in input CPU3, carries out temperature compensation by the operating ambient temperature value detecting; External voltage test circuit 7 is for detection of the supply voltage of power supply 10, and input the storer in CPU3 after 8 tunnel AD converter, CPU3 is according to power supply 10 voltage signals that detect, and judging whether need to be to adopting battery powered power supply 10 to charge, and then the serviceable life of protection power source 10; Keyboard circuit 8 is also inputted the storer in CPU3 by the push button signalling of outside input after 8 tunnel AD converter, by keyboard circuit 8, the parameter of temperature zero drift and temperature span drift can be inputed in CPU3 storer, therefore do not need LOAD CELLS 1 to carry out again the hardware compensating of temperature zero drift and temperature span drift, save technique one, reduced cost.Thermistor temp-resistance the table of comparisons, temperature drift and the temperature span drift curve that by thermistor producer, are provided are also provided in the storer in CPU3, can obtain by computation of table lookup the exact value of the digital weighing apparatus operating ambient temperature of the utility model remote control temperature compensation.

In the various embodiments described above, temperature-compensation circuit 6 comprises measuring resistance 61 and as the pasted sheet type thermistor 62 of temperature element, output signal after measuring resistance 61 and pasted sheet type thermistor 62 series connection, after 8 tunnel AD converter, input in CPU3 internal storage, compare with the thermistor temp-resistance table of comparisons being preset in CPU3 storer, and then obtain the scope of LOAD CELLS 1 temperature correction.When the digital weighing apparatus working temperature of remote control temperature compensation of the present utility model changes from-10 ℃ to+40 ℃, the resistance of thermistor 62 changes to 15.12k Ω from 244.88k Ω, in temperature-resistance table of comparisons of the numerical value that 8 tunnel AD converter are tested in CPU3 storer, search, and then LOAD CELLS 1 temperature error is proofreaied and correct in predefined error range.

In the various embodiments described above, power supply 10 is by stabilized voltage supply DC-DC charge pump 11 output two-way power supplys, be the power supply of AD modular converter 2 and the power supply of CPU3, by the power supply of AD modular converter 2 and CPU3 separately, can effectively improve the antijamming capability of AD modular converter 2.Power supply 10 of the present utility model adopts 5V～2.5V direct supply, and when power supply 10 voltages are when 5V～2.5V fluctuates, stabilized voltage supply DC-DC charge pump 11 can also play pressure stabilization function, and then does not affect testing result.

In the various embodiments described above, because the utility model adopts, AD modular converter 2 and wireless communication module 9 are all arranged on a circuit board, close proximity, there will be very large wireless wave to disturb so between the two.Therefore, the utility model adopts the surrounding at AD modular converter 2 to be provided with paster LC element and the screen layer that absorbs electromagnetic interference (EMI), and adopts AD sampling and wireless receiving and dispatching timesharing partition method, has avoided both interference each other.Timesharing partition method of the present utility model adopts software second-order filter, makes AD modular converter 2 stability very good.

In the various embodiments described above, AD modular converter 2 adopts 24 octal encapsulation conversion chip HX710, and its volume is very little, SOP8 encapsulation, and built-in differential amplification, binary channels is selected, and sampling rate is selected, and programmable functions is switched.

In the various embodiments described above, CPU3 adopts the chip of the high speed 1T TSSOP-20 microencapsulated of STC Corporation, externally be provided with asynchronous communication interface and the high-speed synchronous communication interface of 115200 baud rates at a high speed, built-in FLASH and EEP, 10,8 tunnel high-speed A/D converter, can measure power supply 10 voltages, measure temperature, survey a plurality of buttons, realizing A/D conversion, thermometric, survey key, data processing, wireless receiving and dispatching, weighing arranges and the function such as control.

Wherein, in CPU3, be also provided with key control module, adopt the single-signal-line can external a plurality of buttons, the AD value of each button is stored in the FLASH of CPU3, also on-site proving at any time, test, inspection easily.Each button has able to programme self-defined, for example, when button resistance value alters a great deal suddenly, (generally there will not be), can be online automatic calibration key value very easily.

In the various embodiments described above, external DSP display 4 can adopt LCD, LED, VFD, MCD(dot matrix Chinese display) etc. various displays, also can adopt interim external displaying block, or directly be fixed in LOAD CELLS 1; Wherein, LCD shows low-power consumption.Therefore, by external DSP display 4, can see online at the scene and the process of weighing not need peripheral hardware CPU and software.

In sum, the temp compensation method of the digital weighing apparatus of the utility model remote control temperature compensation, is, in CPU3, the working temperature by LOAD CELLS 1 is carried out to temperature zero compensation and temperature span compensation, and its compensation method is as follows:

1) AD modular converter 2 is by the LOAD CELLS detecting 1 weight signal input CPU3, by CPU3, AD weight signal is carried out to one section or five segment marks fixed (being sensor weight linearization process), the nonlinearity erron of LOAD CELLS 1 is dwindled greatly, after one section or five segment marks are fixed, its linearization mathematics is touched type (being temperature drift and temperature span drift curve) and is solidificated in the storer of CPU3.In order to facilitate user, cost saving, can adopt a segment mark fixed, and having retained original linearization mathematics, to touch type constant, also can reach good effect.

2) temperature zero compensation: temperature drift preset in CPU3 storer and temperature range curve are divided to Shi Ge district within the scope of-10 ℃～+ 40 ℃, each district is 6.4 degree, be divided into 64 compensation steps, in each compensation step, be divided into again 640 compensation blocks, each compensation block is 0.1 degree.8 tunnel AD converter are by code value in the zero-bit AD of the working temperature of the LOAD CELLS recording by temperature-compensation circuit 61, need not calculate in the storer that is directly inputted to CPU3, first in temperature-resistance table of comparisons, find corresponding temperature value, then this temperature value is found to the compensation block approaching with it in corresponding compensation step on temperature drift curve, the variation at having automatic temp compensating zero point, and according to the different Changing Patterns of each senor operating temperature, all-the-way tracking, no longer needs hardware temperatures zero compensation.

3) temperature span compensation: the temperature span drift of LOAD CELLS 1 is different from temperature zero drift, it and the elastic body of LOAD CELLS 1 and the material of foil gauge have main relation, the elasticity coefficient variation with temperature of the elastic feel quantity of every batch of Weighing sensor elastomer and foil gauge is regular, discreteness is smaller, so range temperature compensation is regular, zero-bit compensate for slower is easy relatively.The utility model adopts by recording the drift value of each sensor temperature range, by interface circuit 5 or keyboard circuit 8, the drift value of record is input in the storer of CPU3, according to the temperature of test, by the built-in computation model of CPU, calculated the span compensation value of this temperature, revised.

In sum, temperature-compensation circuit 6 is when carrying out temperature test to LOAD CELLS 1, can record the drift reading of LOAD CELLS 1 temperature zero drift and temperature range, adopt interface circuit 5 or keyboard circuit 8 in the parameter input CPU3 of temperature zero drift and temperature span drift, to store, therefore do not need LOAD CELLS 1 to carry out again the hardware compensating of temperature zero drift and temperature span drift, save technique one, reduced cost.And, because temperature-compensation circuit 6 is at any time in the temperature of measuring LOAD CELLS 1, at any time at compensation temperature zero drift and temperature span drift, greatly improved the qualification rate of LOAD CELLS 1, solved the random performance of LOAD CELLS 1 temperature zero drift.

The various embodiments described above are only for illustrating the utility model; the connection of each parts and structure all can change to some extent; on the basis of technical solutions of the utility model; all improvement and equivalents of the connection of indivedual parts and structure being carried out according to the utility model principle, all should not get rid of outside protection domain of the present utility model.

Claims

1. the digital weighing apparatus of a remote control temperature compensation, it is characterized in that: it comprises LOAD CELLS, AD modular converter, CPU, external DSP display, interface circuit, temperature-compensation circuit, external voltage test circuit, keyboard circuit, the wireless communication module that consists of equal arm bridge four resistance strain gages, and be power supply and the stabilized voltage supply DC-DC charge pump of each parts power supply;

Described LOAD CELLS is converted to the force signal detecting after analog electrical signal, inputs described AD modular converter analog electrical signal is converted to digital signal, and input the gravimetric value that obtains testee after processing in described CPU; The output terminal of described CPU connects described external DSP display and interface circuit, and the input end of described CPU connects described temperature-compensation circuit, and the output terminal of described CPU also connects described wireless communication module;

Described power supply, by described stabilized voltage supply DC-DC charge pump output two-way power supply, is respectively described AD modular converter and CPU power supply.

2. the digital weighing apparatus of a kind of remote control temperature compensation as claimed in claim 1, is characterized in that: in described CPU, be built-in with 8 tunnel AD converter, wherein three tunnels connect respectively described temperature-compensation circuit, external voltage test circuit and keyboard circuit; Described temperature-compensation circuit after described 8 tunnel AD converter, is inputted the operating ambient temperature value detecting in the storer in described CPU, to carry out temperature compensation; Described external voltage test circuit is for detection of the supply voltage of described power supply, and inputs the storer in described CPU after described 8 tunnel AD converter, detects described Power supply state; Described keyboard circuit is also inputted the storer in described CPU by the push button signalling of outside input after described 8 tunnel AD converter, by described keyboard circuit, the parameter of temperature zero drift and temperature span drift is inputed in described CPU storer; Thermistor temp-resistance the table of comparisons, temperature drift and the temperature span drift curve that by thermistor producer, are provided are also provided in the storer in described CPU.

3. the digital weighing apparatus of a kind of remote control temperature compensation as claimed in claim 1, it is characterized in that: described temperature-compensation circuit comprises measuring resistance and as the pasted sheet type thermistor of temperature element, output signal after described measuring resistance and pasted sheet type thermistor series connection, after 8 tunnel AD converter in described CPU, input in described CPU storer, compare with the thermistor temp-resistance table of comparisons being preset in described CPU storer.

4. the digital weighing apparatus of a kind of remote control temperature compensation as claimed in claim 2, it is characterized in that: described temperature-compensation circuit comprises measuring resistance and as the pasted sheet type thermistor of temperature element, output signal after described measuring resistance and pasted sheet type thermistor series connection, after 8 tunnel AD converter in described CPU, input in described CPU storer, compare with the thermistor temp-resistance table of comparisons being preset in described CPU storer.

5. the digital weighing apparatus of a kind of remote control temperature compensation as claimed in claim 1 or 2 or 3 or 4, it is characterized in that: described AD modular converter adopts 24 octal encapsulation conversion chip HX710, and be provided with in the surrounding of described AD modular converter paster LC element and the screen layer that absorbs electromagnetic interference (EMI), and adopting AD sampling and wireless receiving and dispatching timesharing partition method, described timesharing partition method adopts software second-order filter.

6. the digital weighing apparatus of a kind of remote control temperature compensation as claimed in claim 1 or 2 or 3 or 4, is characterized in that: described CPU adopts the chip of the high speed 1T TSSOP-20 microencapsulated of STC Corporation; Described external DSP display adopts LCD, LED, VFD or MCD display.

7. the digital weighing apparatus of a kind of remote control temperature compensation as claimed in claim 5, is characterized in that: described CPU adopts the chip of the high speed 1T TSSOP-20 microencapsulated of STC Corporation; Described external DSP display adopts LCD, LED, VFD or MCD display.