CN209199870U

CN209199870U - A kind of dark current baseline deduction adaptive circuit applied on mass spectrograph

Info

Publication number: CN209199870U
Application number: CN201822139493.3U
Authority: CN
Inventors: 程晓亮; 程文播; 李振; 王晶; 冯新用; 韩文念; 张金鑫; 胡玮; 孙之琳
Original assignee: Tianjin Guo Ke Medical Technology Development Co Ltd
Current assignee: Weigao Guoke mass spectrometry medical technology (Tianjin) Co.,Ltd.
Priority date: 2018-12-19
Filing date: 2018-12-19
Publication date: 2019-08-02
Anticipated expiration: 2028-12-19

Abstract

The utility model provides a kind of dark current baseline deduction adaptive circuit applied on mass spectrograph, including voltage tunable road, current ion signal source, pre-amplifier A1 and comparator A2, the voltage tunable road includes analog-to-digital conversion module A DC, external reference voltage signal Vo passes through analog-to-digital conversion module A DC, digital signal is converted to, the inverting input terminal of comparator A2 is input to；Current ion signal source is amplified by pre-amplifier A1, is input to the normal phase input end of the comparator A2；The utility model can detect the variation of dark current in real time, provide accurate data for baseline deduction, greatly increase the sensitivity of ion detection.

Description

A kind of dark current baseline deduction adaptive circuit applied on mass spectrograph

Technical field

The utility model belongs to mass spectrometer apparatus field, more particularly, to a kind of dark current baseline applied on mass spectrograph Deduct adaptive circuit.

Background technique

Triple level four bars mass spectrographs are due to having the characteristics that highly sensitive, analysis speed is fast, amount of samples is few, conduct Conventional quantitative analytical instrument, is widely used in medicine, biology, chemical industry and environmental science.

Nowadays, channel electron multiplier (Channel is usually used in the mass spectrometric signal deteching circuit of triple level four bars Electron Multiplier, CEM) this channel Electron Mltiplier be used to collect mass analyzer transmitting comes it is to be detected from Son, carries out electronics acceleration for ion in multiplier, forms current ion signal, which is introduced signal processing circuit Carry out the detection of ion concentration.

In normal work, there are the following problems by electron multiplier CEM:

(1) due to channel electron multiplier 380~400 DEG C of high-temperature baking must be born when, intra passage temperature constantly rises It is high；

(2) pollution due to long-term work electron multiplier by atmospheric molecule makes to generate adsorption layer in channel；

Even if electron multiplier CEM is entered without band energy particle, under the action of bias voltage, in electron multiplier The fault location in the channel CEM is produced from electricity subpulse, so as to form dark current, has eventually led to the raising of gain.

Method of the tradition to dark current baseline deduction are as follows:

In equipment debugging, the size of dark current is estimated, baseline is then determined, by adjusting electricity in baseline deduction circuit Position device size is for being arranged threshold value, to realize the baseline deduction to dark current, as shown in Figure 1.

The ion stream transmitted from electron multiplier CEM is converted into voltage by current-to-voltage convertor I/V, the electricity of the ion The amplification Jing Guo prime is pressed, is input to baseline deduction circuit, baseline deduction circuit is made of comparator, the reverse phase of operational amplifier Terminate the voltage tunable road being made of mechanical type variable potentiometer R7 and fixed resistance R5 and R6, the voltage value at input inversion end It is the deduction baseline of electron multiplier CEM, after the comparator that AD9696 is formed, voltage magnitude is greater than the voltage signal of ion When reverse side voltage, signal passes through and is converted to square wave to be counted for next stage circuit.

Above dark current baseline deduction method will be mechanical usually in mass spectrograph before use, by virtue of experience or theory analysis Type variable potentiometer R7 is adjusted to fixed resistance value, and the baseline of such deduction is also fixed therewith, thus the technology there is The baseline of deduction cannot follow the variation of dark current and the defect that timely adaptively adjusts in real time.And mechanical type variable Potentiometer itself has the following deficiencies:

1) precision is difficult to control during debugging；

2) as the variation resistance value fluctuation of environment temperature is larger；

3) frequent debugging influences its service life.

The adaptive circuit for the dark current baseline deduction that this project uses makes improvement aiming at drawbacks described above.

Summary of the invention

In view of this, the utility model be directed to it is a kind of adaptively electric applied to the dark current baseline deduction on mass spectrograph Road, to solve drawbacks described above.

In order to achieve the above objectives, the technical solution of the utility model is achieved in that

A kind of dark current baseline deduction adaptive circuit applied on mass spectrograph, including voltage tunable road, ion stream Signal source, pre-amplifier A1 and comparator A2, the voltage tunable road include analog-to-digital conversion module A DC, external ginseng Voltage signal Vo is examined by analog-to-digital conversion module A DC, digital signal is converted to, is input to the inverting input terminal of comparator A2； Current ion signal source is amplified by pre-amplifier A1, is input to the normal phase input end of the comparator A2.

Further, the analog-to-digital conversion module A DC includes single-chip microcontroller and digital regulation resistance, unit machine and digital regulation resistance Communication connection, the real-time adjustment for controlling dark current are deducted.

Further, the voltage tunable road further includes fixed resistance, and the fixed resistance is connected in parallel on analog-to-digital conversion mould Between group ADC and comparator A2.

Further, the fixed resistance includes the first fixed resistance R5 and the second fixed resistance R6.

Further, an output end of the current ion signal source signal is grounded by R1, another output end and resistance R2 It is connected, an output end of R2 is connected with the positive input of pre-amplifier A1, and another output end is connected with one end of resistance R3, The other end of R3 is connected with the output end of A1.

Further, the output end of the A1 is connected by resistance R4 with the normal phase input end of comparator A2.

Further, the single-chip microcontroller uses the enhanced series monolithic of STM32F103CBT6.

Further, the digital regulation resistance is AD8402 digital regulation resistance.

Compared with the existing technology, described in the utility model a kind of adaptive applied to the dark current baseline deduction on mass spectrograph Circuit is answered to have the advantage that

(1) the utility model can detect the variation of dark current in real time, provide accurate data for baseline deduction, greatly The earth improves the sensitivity of ion detection；

(2) the digital adjustable potentiometer overcomes mechanical potentiometer because of time long the shortcomings that being easy aging；

(3) the utility model overcomes the disadvantage that the precision of mechanical potentiometer resistance value during debugging is difficult to control；

(4) automation is improved using digital adjustable potentiometer and precision is horizontal.

Detailed description of the invention

The attached drawing for constituting a part of the utility model is used to provide a further understanding of the present invention, this is practical new The illustrative embodiments and their description of type are not constituteed improper limits to the present invention for explaining the utility model.? In attached drawing:

Fig. 1 is system schematic described in the utility model background technique；

Fig. 2 is system schematic described in the utility model embodiment.

Specific embodiment

It should be noted that in the absence of conflict, the feature in the embodiments of the present invention and embodiment can To be combined with each other.

In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, term " is pacified Dress ", " connected ", " connection " shall be understood in a broad sense, for example, it may be being fixedly connected, may be a detachable connection, or integrally Connection；It can be mechanical connection, be also possible to be electrically connected；Can be directly connected, can also indirectly connected through an intermediary, It can be the connection inside two elements.For the ordinary skill in the art, on being understood by concrete condition State the concrete meaning of term in the present invention.

The utility model will be described in detail below with reference to the accompanying drawings and embodiments.

As shown in Fig. 2, include voltage tunable road, current ion signal source, pre-amplifier A1 and comparator A2, it is described Voltage tunable road includes analog-to-digital conversion module A DC, and external reference voltage signal Vo passes through analog-to-digital conversion module A DC, conversion For digital signal, it is input to the inverting input terminal of comparator A2；Current ion signal source first passes through Current Voltage and is converted to voltage Signal, then voltage signal is amplified by pre-amplifier A1, is input to the normal phase input end of the modulus comparator A2.

Wherein, the analog-to-digital conversion module A DC includes single-chip microcontroller and digital regulation resistance, and unit machine is communicated with digital regulation resistance Connection, the real-time adjustment for controlling dark current are deducted.

Wherein, the voltage tunable road further includes fixed resistance, and the fixed resistance is connected in parallel on analog-to-digital conversion module A DC Between comparator A2.

Wherein, the fixed resistance includes the first fixed resistance R5 and the second fixed resistance R6.

Wherein, an output end of the current ion signal source signal is grounded by R1, and another output end is connected with resistance R2, An output end of R2 is connected with the positive input of pre-amplifier A1, and another output end is connected with one end of resistance R3, R3's The other end is connected with the output end of A1.

Wherein, the output end of the A1 is connected by resistance R4 with the normal phase input end of comparator A2.

Wherein, the single-chip microcontroller uses the enhanced series monolithic of STM32F103CBT6.

Wherein, the digital regulation resistance is AD8402 digital regulation resistance.

Implementation method of the invention: reference voltage signal Vo is exported by electron multiplier output end, and being transmitted to voltage can Adjust and carry out ADC analog-to-digital conversion in the ARM single-chip microcontroller in circuit, the digital quantity converted into 8, single-chip microcontroller by this 8 bit digital quantity with And 2 bit address data the SDI (serial date transfer of digital regulation resistance AD8402 is transmitted to by the port MOSI of spi bus End) it reaches in digital regulation resistance AD8402, to control the resistance value of digital variable potentiometer；Wherein, the single-chip microcontroller is The enhanced series monolithic of STM32F103CBT6 uses 32 RISC cores of high performance ARM Cortex-M3, work frequency Rate is 72MHz, built-in 2 12 ADC channels and 2 SPI interfaces.

AD8402 is substituted mechanical potentiometer by the utility model, can be by the real-time change of dark current, to control The resistance value of AD8402 guarantees the levels of precision of baseline deduction to adjust the baseline of deduction in real time.

The above is only the preferred embodiment of the utility model only, is not intended to limit the utility model, all at this Within the spirit and principle of utility model, any modification, equivalent replacement, improvement and so on should be included in the utility model Protection scope within.

Claims

1. a kind of dark current baseline deduction adaptive circuit applied on mass spectrograph, it is characterised in that: including voltage tunable Road, current ion signal source, pre-amplifier A1 and comparator A2, the voltage tunable road include analog-to-digital conversion module A DC, External reference voltage signal Vo is converted to digital signal, is input to the reverse phase of comparator A2 by analog-to-digital conversion module A DC Input terminal；Current ion signal source is amplified by pre-amplifier A1, is input to the normal phase input end of the comparator A2.

2. a kind of dark current baseline deduction adaptive circuit applied on mass spectrograph according to claim 1, feature Be: the analog-to-digital conversion module A DC includes single-chip microcontroller and digital regulation resistance, and unit machine and digital regulation resistance are communicated to connect, used It is deducted in the real-time adjustment of control dark current.

3. a kind of dark current baseline deduction adaptive circuit applied on mass spectrograph according to claim 1, feature Be: the voltage tunable road further includes fixed resistance, and the fixed resistance is connected in parallel on analog-to-digital conversion module A DC and comparator Between A2.

4. a kind of dark current baseline deduction adaptive circuit applied on mass spectrograph according to claim 3, feature Be: the fixed resistance includes the first fixed resistance R5 and the second fixed resistance R6.

5. a kind of dark current baseline deduction adaptive circuit applied on mass spectrograph according to claim 1, feature Be: an output end of the current ion signal source signal is grounded by R1, and another output end is connected with resistance R2, and the one of R2 is defeated Outlet is connected with the positive input of pre-amplifier A1, and another output end is connected with one end of resistance R3, the other end of R3 with The output end of A1 is connected.

6. a kind of dark current baseline deduction adaptive circuit applied on mass spectrograph according to claim 1, feature Be: the output end of the A1 is connected by resistance R4 with the normal phase input end of comparator A2.

7. a kind of dark current baseline deduction adaptive circuit applied on mass spectrograph according to claim 2, feature Be: the single-chip microcontroller uses the enhanced series monolithic of STM32F103CBT6.

8. a kind of dark current baseline deduction adaptive circuit applied on mass spectrograph according to claim 2, feature Be: the digital regulation resistance is AD8402 digital regulation resistance.