JPS6213359Y2 - - Google Patents
Info
- Publication number
- JPS6213359Y2 JPS6213359Y2 JP15545880U JP15545880U JPS6213359Y2 JP S6213359 Y2 JPS6213359 Y2 JP S6213359Y2 JP 15545880 U JP15545880 U JP 15545880U JP 15545880 U JP15545880 U JP 15545880U JP S6213359 Y2 JPS6213359 Y2 JP S6213359Y2
- Authority
- JP
- Japan
- Prior art keywords
- tube current
- circuit
- signal
- high voltage
- voltage
- 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
Links
- 230000007935 neutral effect Effects 0.000 claims description 3
- 238000003384 imaging method Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 239000003990 capacitor Substances 0.000 description 2
- 238000004804 winding Methods 0.000 description 2
- 238000001514 detection method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
Landscapes
- X-Ray Techniques (AREA)
Description
【考案の詳細な説明】 この考案は、X線管電流測定回路に関する。[Detailed explanation of the idea] This invention relates to an X-ray tube current measuring circuit.
X線装置の高電圧回路には、高電圧ケーブルの
容量(約250pF/m)や高圧変圧器の浮遊容量等
が存在する。そのため一般に、高圧変圧器の2次
側の中性点で管電流を検出する場合、立上り時に
上記の容量に対するチヤージ電流が流れるため、
管電流信号は第1図に示すように変形され、いわ
ゆる「飛び出し」が生じる。この「飛び出し」は
高圧ケーブルの長さ等によつて異なるが、その高
さが定常値の2〜5倍以上になり、その期間は1
〜2msec程度となる。そのためこれをそのまま管
電流信号として用いると大巾な誤差を生じること
になるため、従来ではこの「飛び出し」が生じて
いる間、別の回路で作つたゲート信号によりゲー
トして「飛び出し」の生じている間は測定しない
ようにし、その後にこの管電流信号によつて測定
した管電流値に測定しなかつた期間分を加算する
ようにしている。したがつて回路構成が複雑なも
のであつた。 The high-voltage circuit of an X-ray device includes the capacitance of the high-voltage cable (approximately 250 pF/m) and the stray capacitance of the high-voltage transformer. Therefore, in general, when detecting tube current at the neutral point on the secondary side of a high-voltage transformer, a charge current for the above capacity flows at the time of startup, so
The tube current signal is transformed as shown in FIG. 1, resulting in a so-called "popout". This "pop-out" varies depending on the length of the high-voltage cable, but the height is 2 to 5 times the steady value, and the period is 1
It will be about ~2msec. Therefore, if this signal is used as a tube current signal as it is, a large error will occur, so conventionally, while this "pop-out" is occurring, a gate signal created in another circuit is used to gate the "pop-out" signal. During this period, no measurement is made, and after that, the amount for the period during which no measurements were taken is added to the tube current value measured using this tube current signal. Therefore, the circuit configuration was complicated.
本考案は、極めて簡単な回路でしかも他の部分
からの信号を必要とせずに、上記の浮遊容量等に
対するチヤージ電流による誤差を除去することの
できる、X線管電流測定回路を提供することを目
的とする。 The object of the present invention is to provide an X-ray tube current measurement circuit that is extremely simple and does not require signals from other parts, and can eliminate errors caused by charge current due to stray capacitance, etc. purpose.
以下、本考案の一実施例について第2図を参照
しながら説明する。第2図において、高圧変圧器
の2次巻線1,2に生じた高電圧は整流回路3
1,32によつて整流された後、X線管4の陰
極、陽極間に印加される。この高電圧回路の中性
点にX線管電流検出用抵抗5が接続され、この抵
抗5の一端に生じた電圧が管電流信号として演算
増巾器6に送られる。こうして増巾された管電流
信号は抵抗8,9及び可変抵抗10よりなる分圧
回路をへて演算増巾器11の非反転入力端子に送
られるとともに、微分回路7に送られる。この微
分回路7はコンデンサ71と抵抗72とでなり、
この微分出力は入力抵抗12をへて演算増巾器1
1の反転入力端子に送られる。抵抗13は帰還用
の抵抗である。この演算増巾器11の出力は電圧
−周波数変換器14に送られ、ここで生じるパル
スがプリセツトカウンタ15によりカウントされ
るようになつている。 An embodiment of the present invention will be described below with reference to FIG. In Figure 2, the high voltage generated in the secondary windings 1 and 2 of the high voltage transformer is transferred to the rectifier circuit 3.
1 and 32, and then applied between the cathode and anode of the X-ray tube 4. An X-ray tube current detection resistor 5 is connected to the neutral point of this high voltage circuit, and the voltage generated at one end of this resistor 5 is sent to an operational amplifier 6 as a tube current signal. The tube current signal amplified in this way is sent to the non-inverting input terminal of the operational amplifier 11 via a voltage dividing circuit made up of resistors 8 and 9 and a variable resistor 10, and is also sent to the differentiating circuit 7. This differentiating circuit 7 consists of a capacitor 71 and a resistor 72,
This differential output passes through an input resistor 12 to an operational amplifier 1.
1 is sent to the inverting input terminal. The resistor 13 is a feedback resistor. The output of the operational amplifier 11 is sent to a voltage-frequency converter 14, and the pulses generated here are counted by a preset counter 15.
演算増巾器6から出力される管電流信号(b点
の信号)は第3図の1点鎖線bで示すように、立
上り時にチヤージ電流による「飛び出し」を有し
ている。この信号が微分回路7で微分されるた
め、微分出力(a点の信号)の反転した波形は第
3図の破線aのようになる。a点の信号は演算増
巾器11の反転入力端子に加えられるため、反転
されたものが加算されると考えてよいわけであ
る。従つて、微分回路7における定数を当該高電
圧回路の浮遊容量と関連させて適当に選択すれ
ば、チヤージ電流分のキヤンセルが可能となる。
本考案者が試した1つの例では、約12mの高電圧
ケーブルを用いた場合でコンデンサ71を0.08μ
F、抵抗72をkΩとしたときに、チヤージ電流分
のキヤンセルができた。 The tube current signal (signal at point b) output from the operational amplifier 6 has a "jump" due to the charge current at the time of rise, as shown by the dashed line b in FIG. Since this signal is differentiated by the differentiating circuit 7, the inverted waveform of the differentiated output (signal at point a) becomes as shown by the broken line a in FIG. Since the signal at point a is applied to the inverting input terminal of the operational amplifier 11, it can be considered that the inverted signal is added. Therefore, if the constant in the differentiating circuit 7 is appropriately selected in relation to the stray capacitance of the high voltage circuit, it is possible to cancel the charge current.
In one example tested by the present inventor, when using a high voltage cable of about 12 m, the capacitor 71 was 0.08μ
When F and resistance 72 are set to kΩ, the charge current can be canceled.
このようにチヤージ電流分のキヤンセルがなさ
れれば演算増巾器11の出力は第3図の実線cに
示すようになり、浮遊容量に影響されない正確な
管電流値を示す。従つて、電圧−周波数変換器1
4は入力電圧に比例した周波数のパルスを出力
し、プリセツトカウンタ15はこのパルスを計数
するため、その全計数値は管電流値と撮影時間の
積となり、すなわちmAs値に相当する。予め所
望のmAs値に相当する計数値をプリセツトカウ
ンタ15にプリセツトしておくことにより、全計
数値がプリセツト値に達したときプリセツトカウ
ンタ15から出力を出じさせることができるの
で、mAsタイマとして働かせることができる。
また、この全計数値をその時の撮影時間で割る
と、管電流(mA)値が得られる。 When the charge current is canceled in this way, the output of the operational amplifier 11 becomes as shown by the solid line c in FIG. 3, indicating an accurate tube current value that is not affected by stray capacitance. Therefore, voltage-frequency converter 1
4 outputs pulses with a frequency proportional to the input voltage, and since the preset counter 15 counts these pulses, the total counted value is the product of the tube current value and the imaging time, that is, corresponds to the mAs value. By presetting the count value corresponding to the desired mAs value in the preset counter 15, the output can be output from the preset counter 15 when all the count values reach the preset value. It can be used as
Furthermore, by dividing this total count value by the imaging time at that time, the tube current (mA) value can be obtained.
なお、上記では管電流信号を直接微分してこの
微分出力でキヤンセルを行なうようにしている
が、他の回路で矩形波等を作りこれを微分してそ
の微分出力を演算増巾器11の反転入力端子に加
えてキヤンセルするように構成してもよい。 Note that in the above example, the tube current signal is directly differentiated and cancellation is performed using this differentiated output, but another circuit generates a rectangular wave, etc., and differentiates this, and the differentiated output is inverted by the operational amplifier 11. It may be configured to cancel in addition to the input terminal.
以上、実施例について説明したように、本考案
によれば、高電圧回路に存在する浮遊容量の影響
を極めて簡単な回路で除去し、正確にX線管電流
の測定を行なうことができる。しかもゲート回路
や他からのゲート信号等も必要としないので、安
価である。特に撮影時間が短時間の場合には、チ
ヤージ電流の流れている時間の占める割合が高く
なるので、これをキヤンセルすることは実際上極
めて大きな効果を生む。また管電流信号に重畳す
るパルス的なノイズもキヤンセルすることが可能
となる。 As described above with respect to the embodiments, according to the present invention, the influence of stray capacitance existing in a high voltage circuit can be removed with an extremely simple circuit, and the X-ray tube current can be accurately measured. Moreover, it is inexpensive because it does not require a gate circuit or a gate signal from another source. Particularly when the imaging time is short, the proportion of time in which the charge current is flowing increases, so canceling this has an extremely large effect in practice. It is also possible to cancel pulse-like noise superimposed on the tube current signal.
第1図は管電流信号の波形を示すタイムチヤー
ト、第2図は本考案の一実施例を示すブロツク
図、第3図は第2図のa,b,c点における電圧
波形を表わすタイムチヤートである。
1,2……高圧変圧器の2次巻線、31,32
……整流回路、4……X線管、5……管電流検出
用抵抗、6,11……演算増巾器、7……微分回
路、14……電圧−周波数変換器、15……プリ
セツトカウンタ。
Fig. 1 is a time chart showing the waveform of the tube current signal, Fig. 2 is a block diagram showing an embodiment of the present invention, and Fig. 3 is a time chart showing the voltage waveform at points a, b, and c in Fig. 2. It is. 1, 2...Secondary winding of high voltage transformer, 31, 32
... Rectifier circuit, 4 ... Set counter.
Claims (1)
性点で検出した管電流信号を微分回路に入力し、
管電流信号の原信号よりこの微分出力を減算し、
減算後の信号で管電流を測定するようにしたこと
を特徴とするX線管電流測定回路。 The tube current signal detected at the neutral point of the high voltage circuit for applying high voltage to the X-ray tube is input to the differentiator circuit,
Subtract this differential output from the original tube current signal,
An X-ray tube current measuring circuit characterized in that a tube current is measured using a signal after subtraction.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP15545880U JPS6213359Y2 (en) | 1980-10-30 | 1980-10-30 |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP15545880U JPS6213359Y2 (en) | 1980-10-30 | 1980-10-30 |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS5776400U JPS5776400U (en) | 1982-05-11 |
JPS6213359Y2 true JPS6213359Y2 (en) | 1987-04-06 |
Family
ID=29514651
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP15545880U Expired JPS6213359Y2 (en) | 1980-10-30 | 1980-10-30 |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS6213359Y2 (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP4505101B2 (en) * | 2000-03-31 | 2010-07-21 | 東芝Itコントロールシステム株式会社 | X-ray generator |
-
1980
- 1980-10-30 JP JP15545880U patent/JPS6213359Y2/ja not_active Expired
Also Published As
Publication number | Publication date |
---|---|
JPS5776400U (en) | 1982-05-11 |
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