JP2818014B2 - Field emission type electron gun - Google Patents
Field emission type electron gunInfo
- Publication number
- JP2818014B2 JP2818014B2 JP2176836A JP17683690A JP2818014B2 JP 2818014 B2 JP2818014 B2 JP 2818014B2 JP 2176836 A JP2176836 A JP 2176836A JP 17683690 A JP17683690 A JP 17683690A JP 2818014 B2 JP2818014 B2 JP 2818014B2
- Authority
- JP
- Japan
- Prior art keywords
- extraction
- voltage
- power supply
- acceleration
- emission current
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Landscapes
- Electron Sources, Ion Sources (AREA)
Description
【発明の詳細な説明】 ［従来の技術］ 従来、第３図に示すような構成の電界放射形電子銃が
知られている。第３図において、１はエミッタ、２は引
き出し電極、３は加速電極、４は引き出し電源、５は加
速電源、６は加速電極に流入するエミッション電流を検
出するための検出器、７は引き出し電源電圧Vext及び加
速電源電圧Vaccを一定のステップ幅で階段状に変化させ
るための制御手段である。[Description of the Related Art] Conventionally, a field emission type electron gun having a configuration as shown in FIG. 3 has been known. In FIG. 3, 1 is an emitter, 2 is an extraction electrode, 3 is an acceleration electrode, 4 is an extraction power supply, 5 is an acceleration power supply, 6 is a detector for detecting an emission current flowing into the acceleration electrode, and 7 is an extraction power supply. This is control means for changing the voltage Vext and the acceleration power supply voltage Vacc stepwise with a constant step width.
電界放射形電子銃においては、前記エミッタ自体の不
安定性に起因して、エミッション電流が経時的に微小に
変動するが、前記検出器６によって検出されたエミッシ
ョン電流値Ieに基づいて、前記制御手段７が前記エミッ
ション電流の変動を補うように引き出し電源４の出力電
圧を第４図（ｂ）に示すように一定のステップ幅で階段
状に変化させている。そのため、エミッション電流値は
同図（ｃ）に示すように略一定値に保たれている。In the field emission type electron gun, the emission current slightly fluctuates with time due to the instability of the emitter itself, but the control is performed based on the emission current value Ie detected by the detector 6. Means 7 changes the output voltage of the extraction power supply 4 in a stepwise manner with a fixed step width as shown in FIG. 4 (b) so as to compensate for the fluctuation of the emission current. Therefore, the emission current value is maintained at a substantially constant value as shown in FIG.
［発明が解決しようとする課題］ ところで、電子プローブマイクロアナライザーなどの
表面分析装置に使用される電子銃として、低エネルギー
の電界放射形電子銃が極めて有効であることが知られて
いる。この低エネルギーの電界放射形電子銃は、エミッ
タと引き出し電極の距離を至近距離乃至はエミッタ先端
が引き出し電極の電子線通過孔内に進入する程度まで接
近して配置すれば、引き出し電圧を下げることができ、
容易に実現可能である。[Problems to be Solved by the Invention] Meanwhile, it is known that a low-energy field emission electron gun is extremely effective as an electron gun used for a surface analyzer such as an electron probe microanalyzer. This low-energy field emission type electron gun can reduce the extraction voltage if the distance between the emitter and the extraction electrode is set to the shortest distance or close enough that the tip of the emitter enters the electron beam passage hole of the extraction electrode. Can be
It can be easily realized.
しかし、上述したようなエミッタ１と引き出し電極２
を接近して配置し、さらに加速電極３を引き出し電極２
の近傍に配置した電子銃では、第４図（ａ）及び（ｂ）
に示すように任意の引き出し電圧Vext1及び任意の加速
電圧Vacc1印加時に、時刻t2において前記加速電圧をV
acc2に変更すると、加速電極３に印加される電圧によっ
て形成される加速電界が、引き出し電極２の電子線通過
孔内に侵入し、エミッタ１と引き出し電極２間に形成さ
れる引き出し電界に重畳され、第４図（ｃ）に示すよう
にエミッション電流が急激に増加することがある。この
エミッション電流の増加は、前記検出器６によって検出
されているため、前述したフィードバック制御によっ
て、該エミッション電流が一定値に保たれるように前記
引き出し電源４が制御されて、該エミッション電流は所
定の値にまで戻され安定する。しかし、該制御はエミッ
ション電流の微小な変動を制御することを目的として、
微小なステップ幅で階段状に印加電圧を変化させている
ため、エミッション電流が安定状態に到達するまでの応
答時間が遅くなり、動作が不安定となることが問題とな
る。However, as described above, the emitter 1 and the extraction electrode 2
Are arranged close to each other, and the accelerating electrode 3 is further pulled out of the electrode 2
(A) and (b) of FIG.
The acceleration voltage during any extraction voltage V ext1 and any acceleration voltage V acc1 applied at time t 2 as shown in V
When it is changed to acc2 , the accelerating electric field formed by the voltage applied to the accelerating electrode 3 penetrates into the electron beam passage hole of the extracting electrode 2 and is superimposed on the extracting electric field formed between the emitter 1 and the extracting electrode 2. As shown in FIG. 4 (c), the emission current may increase rapidly. Since the increase in the emission current is detected by the detector 6, the extraction power supply 4 is controlled by the above-described feedback control so that the emission current is maintained at a constant value. It is returned to the value of and stabilized. However, this control aims at controlling minute fluctuations of the emission current,
Since the applied voltage is changed stepwise with a small step width, the response time until the emission current reaches a stable state becomes slow, and the operation becomes unstable.
そこで、本発明は上述した問題点を考慮し、加速電圧
の大幅な変更に対しても安定なエミッション電流を得る
ことのできる低エネルギーの電界放射形電子銃を提供す
ることを目的としている。In view of the foregoing, an object of the present invention is to provide a low-energy field emission type electron gun capable of obtaining a stable emission current even when the acceleration voltage is largely changed.
［課題を解決するための手段］ 本発明は、エミッタと引き出し電極間に引き出し電圧
を印加する引き出し電源と、エミッタと加速電極間に加
速電圧を印加する加速電源を備えると共に、前記引き出
し電極または加速電極に流入するエミッション電流を検
出し、該エミッション電流値が所定の値に維持されるよ
うに前記引き出し電源電圧または加速電源電圧を一定の
ステップ幅で階段状に変化させて制御する制御手段を具
備した電界放射形電子銃において、前記エミッション電
流値の変化量を検出する手段を設け、該変化量が所定の
値を越えた場合に変化量検出手段の出力信号に基づい
て、前記引き出し電圧を大幅にステップアップまたはス
テップダウンさせるように制御したことを特徴としてい
る。Means for Solving the Problems The present invention includes an extraction power supply for applying an extraction voltage between an emitter and an extraction electrode, and an acceleration power supply for applying an acceleration voltage between an emitter and an acceleration electrode. Control means for detecting an emission current flowing into the electrode and changing and controlling the extraction power supply voltage or the acceleration power supply voltage in a stepwise manner at a fixed step width so that the emission current value is maintained at a predetermined value. In the field emission type electron gun described above, means for detecting a change amount of the emission current value is provided, and when the change amount exceeds a predetermined value, the extraction voltage is greatly increased based on an output signal of the change amount detection means. Is controlled so as to step up or step down.
［作用］ エミッション電流値の変化量を検出する手段を設け、
該変化量が所定の値を越えた場合に変化量検出手段の出
力信号に基づいて、引き出し電圧のステップ幅を変化さ
せるようにしてエミッション電流の変動に対する制御の
応答を速くして、電界放射形電子銃の動作を短時間で安
定させる。[Operation] A means for detecting a change amount of the emission current value is provided,
When the variation exceeds a predetermined value, the response of the control to the variation of the emission current is made faster by changing the step width of the extraction voltage based on the output signal of the variation detector, so that the electric field emission type Stabilizes the operation of the electron gun in a short time.
［実施例］ 以下、本発明の実施例を図面に基づいて説明する。第
１図は本発明の一実施例を説明するための装置構成図。
第２図は動作を説明するための図である。[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is an apparatus configuration diagram for explaining an embodiment of the present invention.
FIG. 2 is a diagram for explaining the operation.
第１図において、第３図と同一の構成要素には同一番
号を付すと共に、説明を省略する。第１図に示す本発明
の実施例が従来例と異なるのは、検出器６によって検出
されたエミッション電流値Ieが供給される微分回路10
と、該微分回路10の出力信号を基準値Ｒと比較するため
の比較回路11と、該比較器の出力信号が基準値Ｒを越え
た期間に亘って前記制御手段から出力される引き出し電
圧の制御信号に任意の電圧を加算するための加算回路12
を設た点である。In FIG. 1, the same components as those in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted. The difference between the embodiment of the present invention shown in FIG. 1 and the conventional example is that a differentiating circuit 10 to which the emission current value Ie detected by the detector 6 is supplied.
A comparison circuit 11 for comparing the output signal of the differentiating circuit 10 with a reference value R; and a drawing voltage of the extraction voltage output from the control means over a period in which the output signal of the comparator exceeds the reference value R. Adder circuit 12 for adding an arbitrary voltage to the control signal
It is the point that was set.
第１図に示すような構成の電界放射形電子銃におい
て、加速電圧をVacc1、引き出し電圧をVext1に設定した
場合、エミッタから放出されるエミッション電流I
e1は、前記エミッタ自体の不安定性に起因して微小に変
動するが、検出器６によって検出されたエミッション電
流値Ieに基づいて、該エミッション電流の変動を補うよ
うに前記引き出し電圧をVext1が、第２図（ｂ）に示す
ように微小ステップ幅で階段状に調整される。そのた
め、エミッション電流値Ieは同図（ｃ）に示すように略
一定の値に保たれる。ここで、第２図（ａ）に示すよう
に、時刻t2において加速電圧をVacc1からVACC2に変更さ
れると、同図（ｃ）中に示されるようにエミッション電
流値は瞬時、増加する。該エミッション電流値の急俊な
変化は微分回路10に供給されて微分されることにより、
該微分回路10より第２図（ｄ）に示されるような微分信
号が出力される。そして該微分信号値が比較回路11に供
給されて基準値Ｒと比較される。該基準値Ｒは電子銃の
構造（各電極間距離、電子線通過穴径等）及び引き出し
電圧対加速電圧の比によって任意に設定されるものであ
る。該微分回路10の出力信号が基準値Ｒを越えた場合、
該信号が基準値Ｒを越えた期間に亘って、比較回路11よ
り出力信号（電圧）が加算回路12に供給される。そし
て、前記制御手段７から出力される引き出し電圧の制御
信号に任意の電圧（この場合負電圧）が加算される。こ
れにより、引き出し電圧のステップ幅が拡大しされるた
め、第２図（ｂ）に示されるように引き出し電圧が急速
に降下される。In the field emission electron gun having the configuration shown in FIG. 1, when the acceleration voltage is set to V acc1 and the extraction voltage is set to V ext1 , the emission current I emitted from the emitter is
e1 fluctuates minutely due to the instability of the emitter itself, but based on the emission current value Ie detected by the detector 6, the extraction voltage Vext1 is compensated for so as to compensate for the fluctuation of the emission current. Is adjusted stepwise with a small step width as shown in FIG. 2 (b). Therefore, the emission current value Ie is maintained at a substantially constant value as shown in FIG. Here, as shown in FIG. 2 (a), the acceleration voltage when it is changed from V acc1 the V ACC2 at time t 2, the emission current value as shown in FIG. (C) is instantaneously increased I do. The rapid change of the emission current value is supplied to the differentiation circuit 10 and differentiated,
A differentiating signal as shown in FIG. 2 (d) is output from the differentiating circuit 10. Then, the differentiated signal value is supplied to the comparison circuit 11 and compared with the reference value R. The reference value R is arbitrarily set according to the structure of the electron gun (distance between the electrodes, the diameter of the electron beam passage hole, etc.) and the ratio of the extraction voltage to the acceleration voltage. When the output signal of the differentiating circuit 10 exceeds the reference value R,
An output signal (voltage) is supplied from the comparison circuit 11 to the addition circuit 12 over a period in which the signal exceeds the reference value R. Then, an arbitrary voltage (in this case, a negative voltage) is added to the control signal of the extraction voltage output from the control means 7. As a result, since the step width of the extraction voltage is increased, the extraction voltage is rapidly decreased as shown in FIG.
そのため、加速電圧変更時のエミッション電流値の変
動は同図（ｃ）に示すように極めて小さく、短時間で一
定値に安定するようになる。Therefore, the variation of the emission current value at the time of changing the acceleration voltage is extremely small as shown in FIG. 3C, and stabilizes at a constant value in a short time.
［発明の効果］ 以上の説明から明らかなように、本発明によれば、エ
ミッタと引き出し電極間に引き出し電圧を印加する引き
出し電源と、エミッタと加速電極間に加速電圧を印加す
る加速電源を備えると共に、前記引き出し電極または加
速電極に流入するエミッション電流を検出し、該エミッ
ション電流値が所定の値に維持されるように前記引き出
し電源電圧または加速電源電圧を一定のステップで階段
状に変化させて制御する制御手段を具備した電界放射形
電子銃において、前記エミッション電流値の変化量を検
出する手段を設け、該変化量が所定の値を越えた場合に
変化量検出手段の出力信号に基づいて、前記引き出し電
圧を大幅にステップアップまたはステップダウンさせる
ように制御したことにより、エミッション電流の変動に
対する制御の応答を一時的に速くすることができるた
め、加速電圧の大幅な変更に対しても短時間に安定なエ
ミッション電流を得ることのできる低エネルギーの電界
放射形電子銃が実現される。[Effects of the Invention] As is apparent from the above description, according to the present invention, there is provided an extraction power supply for applying an extraction voltage between the emitter and the extraction electrode, and an acceleration power supply for applying an acceleration voltage between the emitter and the acceleration electrode. At the same time, the emission current flowing into the extraction electrode or the acceleration electrode is detected, and the extraction power supply voltage or the acceleration power supply voltage is changed in a stepwise manner in a certain step so that the emission current value is maintained at a predetermined value. In a field emission type electron gun provided with control means for controlling, a means for detecting a change amount of the emission current value is provided, and when the change amount exceeds a predetermined value, based on an output signal of the change amount detection means. By controlling the withdrawal voltage to step up or down greatly, fluctuations in emission current can be reduced. Therefore, a low-energy field emission electron gun capable of obtaining a stable emission current in a short time even when the acceleration voltage is largely changed can be realized.
第１図は本発明の一実施例を説明するための装置構成
図。第２図は動作を説明するための図、第３図乃至第４
図は従来例を説明するための図である。 1:エミッタ、2:引き出し電極 3:加速電極、4:引き出し電源 5:加速電源 6:エミッション電流検出器 7:制御手段、10:微分回路 11:比較回路、12:加算回路FIG. 1 is an apparatus configuration diagram for explaining an embodiment of the present invention. FIG. 2 is a diagram for explaining the operation, and FIGS.
The figure is a diagram for explaining a conventional example. 1: Emitter, 2: Extraction electrode 3: Acceleration electrode, 4: Extraction power supply 5: Acceleration power supply 6: Emission current detector 7: Control means, 10: Differentiation circuit 11: Comparison circuit, 12: Addition circuit
Claims (1)
を印加する引き出し電源と、エミッタと加速電極間に加
速電圧を印加する加速電源を備えると共に、前記引き出
し電極または加速電極に流入するエミッション電流を検
出し、該エミッション電流値が所定の値に維持されるよ
うに前記引き出し電源電圧または加速電源電圧を一定の
ステップ幅で階段状に変化させて制御する制御手段を具
備した電界放射形電子銃において、前記エミッション電
流値の変化量を検出する手段を設け、該変化量が所定の
値を越えた場合に変化量検出手段の出力信号に基づい
て、前記引き出し電圧を大幅にステップアップまたはス
テップダウンさせるように制御したことを特徴とする電
界放射形電子銃。1. An extraction power supply for applying an extraction voltage between an emitter and an extraction electrode, an acceleration power supply for applying an acceleration voltage between an emitter and an acceleration electrode, and detecting an emission current flowing into the extraction electrode or the acceleration electrode. A field emission type electron gun comprising control means for controlling the extraction power supply voltage or the acceleration power supply voltage by changing the extraction power supply voltage or the acceleration power supply voltage stepwise with a constant step width so that the emission current value is maintained at a predetermined value. Means for detecting a change amount of the emission current value is provided, and when the change amount exceeds a predetermined value, the extraction voltage is stepped up or down greatly based on an output signal of the change amount detection means. A field emission type electron gun characterized in that:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2176836A JP2818014B2 (en) | 1990-07-04 | 1990-07-04 | Field emission type electron gun |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2176836A JP2818014B2 (en) | 1990-07-04 | 1990-07-04 | Field emission type electron gun |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0465054A JPH0465054A (en) | 1992-03-02 |
| JP2818014B2 true JP2818014B2 (en) | 1998-10-30 |
Family
ID=16020685
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2176836A Expired - Fee Related JP2818014B2 (en) | 1990-07-04 | 1990-07-04 | Field emission type electron gun |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2818014B2 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2852713B2 (en) * | 1992-03-19 | 1999-02-03 | 株式会社日立製作所 | Electron microscope and its use |
| WO2000068970A1 (en) * | 1999-05-11 | 2000-11-16 | Hitachi, Ltd. | Electron beam apparatus, and inspection of electron gun |
| JP3398628B2 (en) * | 1999-09-08 | 2003-04-21 | 福岡丸本株式会社 | Cultivation equipment |
| JP6340165B2 (en) * | 2013-04-25 | 2018-06-06 | 株式会社日立ハイテクノロジーズ | Electron gun, charged particle gun and charged particle beam apparatus using them |
-
1990
- 1990-07-04 JP JP2176836A patent/JP2818014B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0465054A (en) | 1992-03-02 |
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