CN205785249U

CN205785249U - The system of resistance sensor measured by bridge circuit

Info

Publication number: CN205785249U
Application number: CN201620458647.3U
Authority: CN
Inventors: 刘礼亚; 张玉江; 管和平; 仲启端
Original assignee: New United Group Co Ltd
Current assignee: New United Group Co Ltd
Priority date: 2016-05-19
Filing date: 2016-05-19
Publication date: 2016-12-07
Anticipated expiration: 2026-05-19

Abstract

The utility model discloses a kind of bridge circuit and measure the system of resistance sensor, including: the bridge circuit being made up of precision resistance R1, R2, R3 and testing resistance R4；Voltage difference between two brachium pontis of bridge circuit is sampled, is then converted into the analog-digital converter of digital signal；And the voltage source simultaneously powered to bridge circuit and analog-digital converter reference voltage interface.In this utility model, bridge circuit and analog-digital converter reference voltage interface use same voltage source, the digital signal AD that the value of testing resistance R4 is the most corresponding with voltage source₀The digital signal Δ AD corresponding with voltage difference delta U is relevant, eliminates the error brought because of the fluctuation of system operating voltage V, improves accuracy of detection.

Description

The system of resistance sensor measured by bridge circuit

Technical field

This utility model relates to technical field of sensor measurement, and resistance sensor measured by a kind of bridge circuit System.

Background technology

The resistance sensors such as thermistor (temperature) sensor, piezoresistive pickup and photosensitive resistance sensor are by measuring Calculate the value of corresponding resistor, then by tabling look-up or the method for curve matching, inquire about or calculate corresponding temperature, pressure with And the intensity etc. of light.Resistance sensor generally uses bridge circuit to sample analogue signal, with reference to Fig. 1, externally fed power supply Becoming system work required voltage V by level conversion, on the one hand system operating voltage is used for powering to bridge circuit, on the other hand It is converted into ADC reference voltage V through DC/DC transducer_ref, ADC reference voltage is used for supplying to analog-digital converter reference voltage interface Electricity；Microprocessor control analog-digital converter is to the voltage difference sampling Δ U between two brachium pontis, and is converted into digital signal Δ AD.

In prior art, bridge circuit sees the voltage at Fig. 2, R4 and R3 two ends and is respectively U1 and U2, then between two brachium pontis Voltage difference delta U=U1-U2,Obtain:

Set ADC figure place as n, then reference voltage V_refCorresponding full scale digital signal is AD₀=2ⁿ, analog-to-digital conversion device is adopted It is Δ AD that voltage difference delta U of sample is converted into digital signal, then obtain:

In conjunction with formula 1 and formula 2:

ADC reference voltage has smaller fluctuation, and the most accurately, but system operating voltage is by environment, power supply The impact such as the manufacturing process of ripple and voltage chips itself often has larger fluctuation, and system operating voltage is in the range of certain Fluctuation, rather than certain fixed value.Owing to the error of system operating voltage often leads to the value of the testing resistance R4 that computation and measurement goes out Inaccuracy.

Summary of the invention

This utility model is for the low problem of the testing resistance R4 degree of accuracy measured, and research design one bridge circuit Measuring the system of resistance sensor, this utility model uses same voltage source to bridge circuit and analog-digital converter benchmark electricity The method of crimping confession electricity eliminates the measurement error brought because of the instability of system operating voltage.

Technological means of the present utility model is as follows:

The system of resistance sensor measured by a kind of bridge circuit, it is characterised in that including:

The bridge circuit being made up of precision resistance R1, R2, R3 and testing resistance R4；

Voltage difference between two brachium pontis of bridge circuit is sampled, is then converted into the analog-digital converter of digital signal；

And the voltage source simultaneously powered to bridge circuit and analog-digital converter reference voltage interface.

Further, described voltage source is system power supply voltage.

Further, described voltage source is the ADC reference voltage that system power supply voltage is converted into through DC/DC transducer.

Further, described resistance R1 one end connects the positive pole of voltage source, and the other end connects resistance R4；Described resistance R4's The other end connects the negative pole of voltage source；One end of described resistance R2 connects the positive pole of voltage source, and the other end connects R3；Described resistance The other end of R3 connects the negative pole of voltage source；Voltage difference between two brachium pontis is voltage and the resistance R3 two ends at resistance R4 two ends Difference in voltage.

Further, described system also includes microprocessor, and described microprocessor controls analog-digital converter to bridge circuit Voltage difference sampling between two brachium pontis, and accept the digital signal of sampling.

Compared with the prior art, what the system of bridge circuit described in the utility model measurement resistance sensor had has Benefit effect is: voltage and the voltage of analog-digital converter reference voltage interface employing that bridge circuit uses are same voltage source, The digital signal AD that the value of testing resistance R4 is the most corresponding with voltage source₀The digital signal Δ AD corresponding with voltage difference delta U is relevant, disappears The error brought except the fluctuation because of system operating voltage V, reduces cost, improves accuracy of detection.

Accompanying drawing explanation

In order to be illustrated more clearly that the embodiment of the present application or technical scheme of the prior art, below will be to embodiment or existing In having technology to describe, the required accompanying drawing used is briefly described, it should be apparent that, the accompanying drawing in describing below is only this Some embodiments described in application, for those of ordinary skill in the art, on the premise of not paying creative work, Other accompanying drawing can also be obtained according to these accompanying drawings.

Fig. 1 is the system schematic of prior art bridge-type resistance measurement resistance sensor；

Fig. 2 is prior art and embodiment Bridge 1 formula circuit；

Fig. 3 is this utility model embodiment 1 system schematic；

Fig. 4 is this utility model embodiment 2 system schematic；

Fig. 5 is this utility model embodiment Bridge 2 formula circuit.

Detailed description of the invention

For making the purpose of this utility model embodiment, technical scheme and advantage clearer, new below in conjunction with this practicality Accompanying drawing in type embodiment, is clearly and completely described the technical scheme in this utility model embodiment, it is clear that retouched The embodiment stated is a part of embodiment of this utility model rather than whole embodiments.Based on the enforcement in this utility model Example, the every other embodiment that those of ordinary skill in the art are obtained under not making creative work premise, broadly fall into The scope of this utility model protection.

Embodiment 1

The system of bridge-type resistance measurement resistance sensor as shown in Figure 3, in conjunction with Fig. 2, externally fed power supply is by electricity Flat turn changes system work required voltage V into, and on the one hand system operating voltage is used for powering to bridge circuit, on the other hand gives modulus Converter voltage reference interface is powered；Microprocessor control analog-digital converter between two brachium pontis voltage difference sample Δ U, and It is converted into digital signal Δ AD.

The voltage at R4 and R3 two ends is respectively U1 and U2, then voltage difference delta U=U1-U2 between two brachium pontis,Obtain:

It is AD that initialization system running voltage V changes into digital signal₀, voltage difference delta U of analog-to-digital conversion device sampling is converted into Digital signal is Δ AD, then obtain:

In conjunction with formula 4 and formula 5:

Then:

As a kind of preferred implementation of the present utility model, choose R1=R2=R3=R, then can draw:

Concrete measuring method is:

S1, system operating voltage V power to bridge circuit and analog-digital converter reference voltage interface simultaneously；

Voltage difference delta U between two brachium pontis of bridge circuit is sampled by S2, analog-digital converter, and is converted into digital signal Δ AD；Analog-digital bit is n, then corresponding for system operating voltage V full scale digital signal is AD₀=2ⁿ, then

S3, microprocessor are according to formulaCalculate testing resistance R4 Value.

Optional R1=R2=R3=R, then microprocessor is according to formulaCalculate electricity to be measured Resistance R4.

Embodiment 2

The system of bridge-type resistance measurement resistance sensor as shown in Figure 4, in conjunction with Fig. 5, externally fed power supply is by electricity Flat turn changes system work required voltage V into, and system operating voltage is converted into ADC reference voltage V by DC/DC transducer_ref, ADC Reference voltage V_refOn the one hand it is used for powering to bridge circuit, powers on the other hand to analog-digital converter reference voltage interface；Micro-place Reason device control analog-digital converter is to the voltage difference sampling Δ U between two brachium pontis, and is converted into digital signal Δ AD.

In conjunction with formula 9 and formula 10:

Then:

As one preferred embodiment, choose R1=R2=R3=R, then:

Concrete measuring method is:

S1, ADC reference voltage V_refPower to bridge circuit and analog-digital converter reference voltage interface simultaneously；

Voltage difference delta U between two brachium pontis of bridge circuit is sampled by S2, analog-digital converter, and is converted into digital signal Δ AD；Analog-digital bit is n, then ADC reference voltage V_refCorresponding full scale digital signal is AD₀=2ⁿ, then

The above, only this utility model preferably detailed description of the invention, but protection domain of the present utility model is not Being confined to this, any those familiar with the art is in the technical scope that this utility model discloses, according to this practicality Novel technical scheme and inventive concept equivalent or change in addition thereof, all should contain protection domain of the present utility model it In.

Claims

1. the system of a bridge circuit measurement resistance sensor, it is characterised in that including:

The system of resistance sensor measured by bridge circuit the most according to claim 1, it is characterised in that described voltage source For system power supply voltage.

The system of resistance sensor measured by bridge circuit the most according to claim 1, it is characterised in that described voltage source The ADC reference voltage being converted into through DC/DC transducer for system power supply voltage.

The system of resistance sensor measured by bridge circuit the most according to claim 1, it is characterised in that described resistance R1 One end connects the positive pole of voltage source, and the other end connects resistance R4；The other end of described resistance R4 connects the negative pole of voltage source；Described One end of resistance R2 connects the positive pole of voltage source, and the other end connects R3；The other end of described resistance R3 connects the negative pole of voltage source； Voltage difference between two brachium pontis is the voltage difference in voltage with resistance R3 two ends at resistance R4 two ends.

5. measure the system of resistance sensor according to the bridge circuit described in any one of claim 1-4, it is characterised in that institute System of stating also includes microprocessor, and described microprocessor controls analog-digital converter to the voltage difference between two brachium pontis of bridge circuit Sampling, and accept the digital signal of sampling.