JP3959221B2 - Ionization measuring device - Google Patents

Ionization measuring device Download PDF

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JP3959221B2
JP3959221B2 JP2000050439A JP2000050439A JP3959221B2 JP 3959221 B2 JP3959221 B2 JP 3959221B2 JP 2000050439 A JP2000050439 A JP 2000050439A JP 2000050439 A JP2000050439 A JP 2000050439A JP 3959221 B2 JP3959221 B2 JP 3959221B2
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output
value
current
count
electrode
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JP2001236921A (en
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幸治 立花
将三 阪本
朋之 飛田
宏明 橋本
信之 柴田
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Hitachi Ltd
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Hitachi Ltd
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Description

【0001】
【発明の属する技術分野】
本発明は、試料ガスをイオン化して計測を行う装置に関し、特に、針状電極に高電圧を加えてイオン化機能を有するイオン化質量分析計などのイオン化計測装置に関する。
【0002】
【従来の技術】
従来のイオン化計測装置、例えば、イオン化質量分析計は、特開平10−92373号の「大気圧イオン化質量分析計」で記載されているとおり、針状電極に高電圧定電圧源を印加し、コロナ放電を発生させ、試料ガスをイオン化し、質量分析部に導入して試料ガスの質量成分を計測している。
【0003】
【発明が解決しようとする課題】
しかしながら、上記の従来技術では、針状電極が、例えば、試料ガスにより、針先が汚れた場合には、コロナ放電の状態が変化し、試料ガスのイオン化が変動するため、針状電極を清掃または交換する必要がある。その場合、質量分析部を介して質量計測値の変動が発生、などの計測結果から判断して交換を行っており、質量変動が、針状電極の汚れによるものか、あるいは他の要因によるものかを判定をする必要があり、針状電極の箇所のみの異常検出法としては十分に考慮されていなかった。
【0004】
本発明の目的は、針状電極の状態を、針状電極に印加している高圧定電流源の電流値の変動として捉え、異常検出を可能とする針状電極異常検出回路およびそれを用いたイオン化計測装置を提供することにある。
【0005】
【課題を解決するための手段】
上記目的を達成するために、本発明では、針状電極の汚れなどによる影響を、安定状態での一定した放電電流と、汚れなどによる不正規のパルス状に変化する放電電流の変化との相違として捉える。
【0006】
具体的には、イオン化計測装置において、高電圧定電流源と、前記高電圧定電流源に接続された針状電極を有し、該針状電極に放電を発生させて導入した試料ガスをイオン化するイオン化部と、イオン化した該試料ガスを計測する分析部と、前記高電圧定電流源と前記イオン化部の接地電極間に設けられた電流検出抵抗と、該電流検出抵抗に流れる電流値を電圧値として検出し出力する電流検出部と、該電流検出部の出力をデジタル信号に変換するA/D変換部と、前記A/D変換部からデジタル信号を取り込み、取り込んだデジタル信号を微分演算した変分信号とし、該変分信号が閾値を超えた場合は、内部のカウントレジスタに1を加算し、前記カウントレジスタの値が、接続された設定ダイヤルで設定された異常値を示す値を超えた場合、出力をONするマイクロプロセッサと、前記マイクロプロセッサからの出力に基づいてON又はOFFの出力信号を出力するデジタル出力レジスタとを具備し、前記デジタル出力レジスタからの出力は、前記針状電極の状態が正常又は異常であることを示す出力であることを特徴とする。
【0007】
また、イオン化計測装置において、高電圧定電流源と、前記高電圧定電流源に接続された針状電極を有し、該針状電極にコロナ放電を発生させて導入した試料ガスをイオン化するイオン化部と、イオン化した該試料ガスを計測する分析部と、前記高電圧定電流源と前記イオン化部の接地電極間に設けられ、流れる電流の電流値を電圧値へ変換する電流検出抵抗と、前記電圧値を、信号増幅し、微分演算を行い、電流変化を捉えてパルス信号を出力するアンプを有する電流検出部と、電流検出部から出力された前記パルス信号から電流変化の回数を一定時間毎に計数して電流変化の計数値とし、該電流変化の計数値を出力するカウントICと、前記カウントICの出力である計数値と、予め設定ダイヤルにより設定された電流変化を異常とする電流変化の計数値の閾値とを比較し、前記カウントICの計数値が大きい場合は出力をONにするコンパレータICと、前記コンパレータICからの出力を取込み出力するラッチICとを具備し、前記ラッチICからの出力は、前記針状電極の状態が正常又は異常であることを示す出力であることを特徴とする。
【0009】
【発明の実施の形態】
以下、図面を用いて、本発明の一実施例をイオン化質量分析計に適用した場合について説明する。
【0010】
図1は、本発明を用いた内部構成図である。図1において、試料ガスはイオン化部1に入る。イオン化部1は、針状電極2を有し、針状電極2は、高圧定電流源5と接続する。高圧定電流源5に印加した高電圧でコロナ放電を発生する。コロナ放電により、試料ガスは、イオン化し、イオン化部に印加した電界により、質量分析部3に導入する。試料ガスは、質量分析部3でイオン強度より質量分析を行いその結果を、例えば、マススペクトルとしてデータ処理部4で表示を行う。
【0011】
針状電極2に印加した電流値は、電流検出抵抗6で電圧値に変換する。変換された電圧は、電流検出部7において信号増幅回路と微分回路で信号が変化した場合にパルス出力を行う。パルス計数回路8は、パルス出力を一定周期間、例えば、一定時間毎に計数し、計数値を出力する。計数比較回路9は、計数値と、電流変化を異常とする閾値の設定ダイヤル10の数値とを比較し、設定ダイヤル10の値を超えた場合は、針状電極の異常信号を出力する。
【0012】
図2は、上記実施例の回路構成図を示す。高圧定電流源5から針状電極2に印加した電流値は、電流検出抵抗6で電圧値に変換し、演算増幅器よりなるバッファアンプ7aでインピーダンス変換を行い電圧出力する。アンプ7bで信号増幅を行う。アンプ7cで微分演算を行い、電流変化を捉えパルス信号を出力する。カウントIC8aは、パルス信号を計数し、計数値を出力する。
【0013】
マルチバイブレータIC8bは、コンデンサと抵抗の定数で決まる周波数で信号出力し、信号ONの立上がりでカウントIC8aの計数値のリセットをする。コンパレータIC9aと9cは、カウントIC8aの計数値と設定ダイヤル10aと10bを比較し、計数値が設定ダイヤルの値より大きくなった場合、出力をONにする。ラッチIC9bと9dは、マルチバイブレータIC8bの信号のONの立上がりに同期して、コンパレータIC出力を取込み、出力する。出力信号は、表示ランプLEDなどの表示手段に接続し、針状電極が異常となったことを外部に表示する。
【0014】
本実施例では、コンパレータICと設定ダイヤルを各々2個設け、設定ダイヤルの設定値を2段階とすることにより、針状電極の変動を小の場合と大の場合に分ける。変動小がONの場合は、針状電極が汚れ始め、メンテナンスが近づいたことを表示し、変動大がONの場合は、針状電極の汚れがひどく、早急なメンテナンスを行うことを表示する。このように、2段階警報によりメンテナンス性を向上させることができる。
【0015】
図3に、動作タイミングチャートを示す。放電電流のパルス状の変化の個数に対応してカウントICが計数値を出力する。カウントIC出力は、マルチバイブレータIC出力のOFFからONのタイミングで計数値をリセットする。コンパレータIC出力1は、設定ダイヤル1よりカウント出力が越えた場合に出力1をONする。コンパレータIC出力2は、設定ダイヤル2よりカウント出力が超えた場合に出力2をONする。
【0016】
ラッチIC出力1は、マルチバイブレータIC出力のOFFからONのタイミングでコンパレータIC出力1を取込み、保持する。ラッチIC出力2は、マルチバイブレータIC出力のOFFからONのタイミングでコンパレータIC出力2を取込み、保持する。ラッチIC出力1と2は、警報出力1と2となり、針状電極の異常を示す。
【0017】
図4に、マイクロプロセッサでの針状電極異常検出回路の構成を示す。高圧定電流源5、針状電極2、電流検出抵抗6、バッファアンプ7a、アンプ7bまでの構成は、前述した図2の回路構成と同様に構成できる。アンプ7bの出力は、A/D変換器11でアナログ信号からデジタル信号に変換する。
【0018】
デジタル信号はマイクロプロセッサ12に取り込み、マイクロプロセッサ12内で、微分演算TD・S/(1+TD・S/K)を行い、変分信号とし、変分信号が閾値を超えた場合は、マイクロプロセッサ12のカウントレジスタに1を加算する。カウントレジスタが、設定ダイヤル10aと10bの値との比較を行い、超えた場合、出力1または出力2をONにする。デジタル出力レジスタ13は、マイクロプロセッサ12からの出力1または出力2をONまたはOFFの信号として出力する。
【0019】
【発明の効果】
以上のように、本発明によれば、針状電極の電流変化を捉え、電流変化が閾値を超えた場合に異常を出力し、異常を見て針状電極のメンテナンスを行うことができるため、すぐに針状電極清掃または交換のメンテナンスが可能となる効果がある。
【図面の簡単な説明】
【図1】本発明の一実施例を示す内部構成図。
【図2】図1の回路構成の一例を示す図。
【図3】図1の動作タイミングチャート。
【図4】マイクロプロセッサを適用した場合の針状電極異常検出回路の構成を示す図。
【符号の説明】
1…イオン化部、2…針状電極、3…質量分析部、4…データ処理部、5…高圧定電流源、6…電流検出抵抗、7…電流検出部、8…パルス計数回路、9…計数比較回路、10…設定ダイヤル、11…A/D変換器、12…マイクロプロセッサ、13…デジタル出力レジスタ。
[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for measuring by ionizing a sample gas, and more particularly to an ionization measuring apparatus such as an ionization mass spectrometer having an ionization function by applying a high voltage to a needle electrode.
[0002]
[Prior art]
A conventional ionization measurement apparatus, for example, an ionization mass spectrometer, is described in Japanese Patent Application Laid-Open No. 10-92373, “atmospheric pressure ionization mass spectrometer”, by applying a high voltage constant voltage source to a needle electrode, A discharge is generated, the sample gas is ionized, and introduced into the mass analyzer to measure the mass component of the sample gas.
[0003]
[Problems to be solved by the invention]
However, in the above-described prior art, when the needle tip is contaminated by the sample gas, for example, the state of the corona discharge changes and the ionization of the sample gas fluctuates, so the needle electrode is cleaned. Or need to be replaced. In that case, it is exchanged by judging from the measurement result such as occurrence of fluctuation of the mass measurement value through the mass analyzer, and the mass fluctuation is due to contamination of the needle electrode or other factors Therefore, it has not been sufficiently considered as a method for detecting an abnormality only in the location of the needle electrode.
[0004]
An object of the present invention is to detect a state of a needle-like electrode as a change in a current value of a high-voltage constant current source applied to the needle-like electrode, and to use a needle-like electrode abnormality detection circuit capable of detecting an abnormality. The object is to provide an ionization measuring apparatus.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, the influence due to the contamination of the needle electrode is different between the constant discharge current in the stable state and the change in the discharge current that changes into an irregular pulse due to the contamination. As
[0006]
Specifically, in an ionization measurement apparatus, a high-voltage constant current source and a needle electrode connected to the high-voltage constant current source are ionized, and a sample gas introduced by generating a discharge in the needle electrode is ionized. An ionization unit that performs measurement, an analysis unit that measures the ionized sample gas, a current detection resistor provided between the high-voltage constant current source and a ground electrode of the ionization unit, and a value of a current flowing through the current detection resistor A current detection unit that detects and outputs a value, an A / D conversion unit that converts the output of the current detection unit into a digital signal, and a digital signal that is acquired from the A / D conversion unit, and the acquired digital signal is subjected to a differential operation. If the variation signal exceeds the threshold value, 1 is added to the internal count register, and the value of the count register exceeds the value indicating the abnormal value set by the connected setting dial. Where A microprocessor that turns on the output, and a digital output register that outputs an ON or OFF output signal based on the output from the microprocessor, and the output from the digital output register is the state of the needle electrode Is an output indicating that it is normal or abnormal .
[0007]
In the ionization measuring apparatus , the ionization apparatus has a high voltage constant current source and a needle electrode connected to the high voltage constant current source, and ionizes a sample gas introduced by generating a corona discharge in the needle electrode . a Department, an analysis unit that measures the ionized sample gas is provided between the ground electrodes of the high-voltage constant-current source and the ionization portion, a current detection resistor for converting the current value of the current flowing into the voltage value, the A current detection unit having an amplifier that amplifies a voltage value, performs differential operation, captures a current change, and outputs a pulse signal, and counts the number of current changes from the pulse signal output from the current detection unit at regular intervals. The count IC that outputs the count value of the current change, the count value that is the output of the count IC, and the current change preset by the setting dial is abnormal. A comparator IC that compares a count value threshold value of the flow change and turns on an output when the count value of the count IC is large, and a latch IC that takes in and outputs an output from the comparator IC, and The output from the IC is an output indicating that the state of the needle electrode is normal or abnormal .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the case where an embodiment of the present invention is applied to an ionization mass spectrometer will be described with reference to the drawings.
[0010]
FIG. 1 is an internal configuration diagram using the present invention. In FIG. 1, the sample gas enters the ionization unit 1. The ionization unit 1 has a needle electrode 2, and the needle electrode 2 is connected to a high voltage constant current source 5. Corona discharge is generated at a high voltage applied to the high-voltage constant current source 5. The sample gas is ionized by corona discharge, and is introduced into the mass analysis unit 3 by an electric field applied to the ionization unit. The sample gas is subjected to mass analysis from the ion intensity in the mass analyzer 3 and the result is displayed in the data processor 4 as a mass spectrum, for example.
[0011]
The current value applied to the needle electrode 2 is converted into a voltage value by the current detection resistor 6. The converted voltage is output as a pulse when the signal is changed in the signal amplifying circuit and the differentiating circuit in the current detector 7. The pulse counting circuit 8 counts the pulse output for a certain period, for example, every certain time, and outputs a count value. The count comparison circuit 9 compares the count value with the numerical value of the threshold setting dial 10 that makes the current change abnormal, and when the value of the setting dial 10 is exceeded, outputs an abnormal signal of the needle electrode.
[0012]
FIG. 2 shows a circuit configuration diagram of the above embodiment. The current value applied to the needle electrode 2 from the high-voltage constant current source 5 is converted into a voltage value by the current detection resistor 6, and impedance conversion is performed by the buffer amplifier 7a made of an operational amplifier to output a voltage. Signal amplification is performed by the amplifier 7b. The differential calculation is performed by the amplifier 7c, the current change is captured and a pulse signal is output. The count IC 8a counts pulse signals and outputs a count value.
[0013]
The multivibrator IC 8b outputs a signal at a frequency determined by the constant of the capacitor and the resistor, and resets the count value of the count IC 8a at the rising edge of the signal ON. The comparators IC9a and 9c compare the count value of the count IC 8a with the setting dials 10a and 10b, and when the count value becomes larger than the value of the setting dial, the output is turned ON. The latch ICs 9b and 9d take in and output the comparator IC output in synchronization with the ON rise of the signal of the multivibrator IC 8b. The output signal is connected to a display means such as a display lamp LED, and externally indicates that the needle electrode has become abnormal.
[0014]
In this embodiment, two comparator ICs and two setting dials are provided, and the setting values of the setting dial are set in two stages, so that the variation of the needle electrode is divided into a small case and a large case. When the small fluctuation is ON, the needle electrode begins to get dirty and maintenance is approaching. When the large fluctuation is ON, the needle electrode is severely dirty and prompt maintenance is displayed. Thus, maintainability can be improved by the two-stage alarm.
[0015]
FIG. 3 shows an operation timing chart. The count IC outputs a count value corresponding to the number of pulse-like changes in the discharge current. The count IC output resets the count value at the timing when the multivibrator IC output is turned from OFF to ON. The comparator IC output 1 is turned ON when the count output exceeds the setting dial 1. The comparator IC output 2 turns ON the output 2 when the count output exceeds the setting dial 2.
[0016]
The latch IC output 1 captures and holds the comparator IC output 1 at the timing of turning off the multivibrator IC output. The latch IC output 2 captures and holds the comparator IC output 2 at the timing from the OFF to the ON of the multivibrator IC output. Latch IC outputs 1 and 2 become alarm outputs 1 and 2, indicating an abnormality of the needle electrode.
[0017]
FIG. 4 shows the configuration of the needle electrode abnormality detection circuit in the microprocessor. The configuration up to the high voltage constant current source 5, the needle electrode 2, the current detection resistor 6, the buffer amplifier 7a, and the amplifier 7b can be configured in the same manner as the circuit configuration of FIG. The output of the amplifier 7b is converted from an analog signal to a digital signal by the A / D converter 11.
[0018]
The digital signal is taken into the microprocessor 12, and the differential operation TD · S / (1 + TD · S / K) is performed in the microprocessor 12 to obtain a variation signal. When the variation signal exceeds the threshold value, the microprocessor 12 1 is added to the count register. The count register compares the values of the setting dials 10a and 10b, and when it exceeds, the output 1 or the output 2 is turned ON. The digital output register 13 outputs the output 1 or the output 2 from the microprocessor 12 as an ON or OFF signal.
[0019]
【The invention's effect】
As described above, according to the present invention, it is possible to capture the current change of the needle electrode, output an abnormality when the current change exceeds the threshold value, and perform maintenance of the needle electrode by seeing the abnormality. There is an effect that maintenance of needle electrode cleaning or replacement can be performed immediately.
[Brief description of the drawings]
FIG. 1 is an internal configuration diagram showing an embodiment of the present invention.
FIG. 2 is a diagram showing an example of the circuit configuration of FIG.
FIG. 3 is an operation timing chart of FIG. 1;
FIG. 4 is a diagram showing a configuration of a needle electrode abnormality detection circuit when a microprocessor is applied.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Ionization part, 2 ... Needle electrode, 3 ... Mass analysis part, 4 ... Data processing part, 5 ... High voltage constant current source, 6 ... Current detection resistance, 7 ... Current detection part, 8 ... Pulse counting circuit, 9 ... Count comparison circuit, 10 ... setting dial, 11 ... A / D converter, 12 ... microprocessor, 13 ... digital output register.

Claims (3)

高電圧定電流源と、
前記高電圧定電流源に接続された針状電極を有し、該針状電極に放電を発生させて導入した試料ガスをイオン化するイオン化部と、
イオン化した該試料ガスを計測する分析部と
前記高電圧定電流源と前記イオン化部の接地電極間に設けられた電流検出抵抗と、
該電流検出抵抗に流れる電流値を電圧値として検出し出力する電流検出部と、
該電流検出部の出力をデジタル信号に変換するA/D変換部と、
前記A/D変換部からデジタル信号を取り込み、取り込んだデジタル信号を微分演算した変分信号とし、該変分信号が閾値を超えた場合は、内部のカウントレジスタに1を加算し、前記カウントレジスタの値が、接続された設定ダイヤルで設定された異常値を示す値を超えた場合、出力をONするマイクロプロセッサと、
前記マイクロプロセッサからの出力に基づいてON又はOFFの出力信号を出力するデジタル出力レジスタとを具備し、
前記デジタル出力レジスタからの出力は、前記針状電極の状態が正常又は異常であることを示す出力であることを特徴とするイオン化計測装置。
A high voltage constant current source ;
An ionization unit that has a needle electrode connected to the high voltage constant current source, ionizes a sample gas introduced by generating a discharge in the needle electrode ;
An analyzer for measuring the ionized sample gas ;
A current detection resistor provided between the high voltage constant current source and a ground electrode of the ionization unit ;
A current detection unit that detects and outputs a current value flowing through the current detection resistor as a voltage value;
An A / D converter that converts the output of the current detector into a digital signal;
A digital signal is captured from the A / D converter, and the captured digital signal is converted into a variational signal. When the variational signal exceeds a threshold value, 1 is added to an internal count register, and the count register When the value of exceeds the value indicating the abnormal value set with the connected setting dial, a microprocessor that turns on the output;
A digital output register that outputs an ON or OFF output signal based on the output from the microprocessor;
The output from the digital output register is an output indicating that the state of the needle-like electrode is normal or abnormal .
高電圧定電流源と、
前記高電圧定電流源に接続された針状電極を有し、該針状電極にコロナ放電を発生させて導入した試料ガスをイオン化するイオン化部と、
イオン化した該試料ガスを計測する分析部と、
前記高電圧定電流源と前記イオン化部の接地電極間に設けられ、流れる電流の電流値を電圧値へ変換する電流検出抵抗と、
前記電圧値を、信号増幅し、微分演算を行い、電流変化を捉えてパルス信号を出力するアンプを有する電流検出部と、
電流検出部から出力された前記パルス信号から電流変化の回数を一定時間毎に計数して電流変化の計数値とし、該電流変化の計数値を出力するカウントICと、
前記カウントICの出力である計数値と、予め設定ダイヤルにより設定された電流変化を異常とする電流変化の計数値の閾値とを比較し、前記カウントICの計数値が大きい場合は出力をONにするコンパレータICと、
前記コンパレータICからの出力を取込み出力するラッチICとを具備し、
前記ラッチICからの出力は、前記針状電極の状態が正常又は異常であることを示す出力であることを特徴とするイオン化計測装置。
A high voltage constant current source ;
An ionization unit that has a needle electrode connected to the high voltage constant current source, ionizes a sample gas introduced by generating a corona discharge in the needle electrode ;
An analyzer for measuring the ionized sample gas ;
A current detection resistor provided between the high voltage constant current source and the grounding electrode of the ionization unit and converting a current value of a flowing current into a voltage value ;
A current detection unit having an amplifier that amplifies the voltage value, performs differential operation, captures a current change, and outputs a pulse signal;
A count IC that counts the number of current changes from the pulse signal output from the current detection unit at regular intervals to obtain a current change count value, and outputs the current change count value;
The count value that is the output of the count IC is compared with the threshold value of the current change count value that makes the current change preset by the setting dial abnormal. If the count value of the count IC is large, the output is turned ON. A comparator IC to perform,
A latch IC that takes in and outputs an output from the comparator IC;
The output from the latch IC is an output indicating that the state of the needle-like electrode is normal or abnormal .
請求項1又は請求項2において、
前記針状電極の状態が異常であることを示す出力があった場合、前記針状電極の状態が異常になったことを表示する表示手段を付加してなることを特徴するイオン化計測装置。
In claim 1 or claim 2,
An ionization measuring apparatus comprising: a display means for displaying that the state of the needle-like electrode is abnormal when there is an output indicating that the state of the needle-like electrode is abnormal .
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