JPH01243353A - Dc high-voltage generator - Google Patents

Abstract

PURPOSE:To stabilize a DC high-voltage signal and obtain an output response at a high speed when the voltage value is changed by feeding the DC high- voltage signal to an error amplifier to compare it with the reference signal and controlling the output signal of an AC low-voltage power source with the output signal of the error amplifier. CONSTITUTION:A signal generated by an AC low-voltage power source 4 is stepped up by a booster transformer 5 and converted into a DC high-voltage signal via a rectifying booster circuit 6, the converted DC high-voltage signal is applied to the first error amplifier 8 to be compared with the first reference signal power source 9, the amplitude of the output signal of the power source 4 is controlled by the error signal from this amplifier 8. This stabilized output signal is applied to a high-voltage control circuit 20, the output signal is compared with the reference voltage of the second comparison voltage source 23, the output of the circuit 20 is controlled, and the output signal is stabilized. Voltage values of the first and second reference signals 9 and 23 are changed in relation to each other, the DC high-voltage signal is stabilized, a high-speed response is obtained when the power source voltage is changed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a direct current high voltage generator used in a load, heavy particle beam device, etc. The present invention relates to a DC high voltage generator suitable for use as a power source for capturing electron multiplier tubes and the like.

[Conventional technology] Conventionally, in electron microscopes, focused ion beam devices, etc.
It is possible to detect secondary electrons and secondary ions emitted from a sample or material irradiated with a charged particle beam, and to analyze the surface of the sample or display the state of the sample surface as an image based on the detected signals. It is being done. In a charged particle beam device as shown in Fig. 2, a material is irradiated with a charged particle beam, and secondary electrons or secondary ions emitted from the material are transferred to a microchannel plate (
(hereinafter referred to as MCP) to obtain the state of the material surface as an image.

In Figure 2, 1 is a charged particle beam, 2 is a material, and 3 is an MCP.
, 4 is an AC low voltage power supply, 5 is a step-up transformer, 6 is a rectifier step-up circuit, 7 is a voltage detection resistor, 8 is an error amplifier, 9 is a reference signal power supply, 10 is an MCP entrance surface electrode, 11 is an MCP exit surface electrode, 12 is an anode electrode, 13 is a detection signal amplifier,
14 is an amplifier power supply, and 15 is an optical signal transmitter.

A signal generated by the AC low-voltage power supply 4 is boosted via a step-up transformer 5 and converted into a DC high-voltage signal via a rectifier booster circuit, such as a Kotscroft-Walton circuit 6. The DC high voltage signal is detected via a voltage detection resistor 7 and supplied to an error amplifier 8. Then, in the error amplifier 8, the output signal obtained by comparing the voltage of the reference signal power source 9 and the detected voltage is used to control the amplitude of the output signal of the AC low voltage power source 4, thereby stabilizing the DC high voltage signal. . A DC high voltage signal obtained by the DC high voltage generator having such a configuration is applied between the entrance surface electrode 10 and the exit surface electrode 11 of the MCP 3.

In addition, when detecting secondary electrons, the changeover switch S is set to a so that a positive voltage is applied to the entrance surface electrode 10 of the MCP3.
When detecting secondary ions or reflected electrons, the changeover switch S is connected to the b side and a negative voltage is applied.

By the way, secondary electrons or secondary ions emitted from the material 2 by irradiation with the charged particle beam 1 enter the MCP 3 disposed above the material 2 and are multiplied, and then the anode electrode 12
is captured and outputs a detection signal. However, since this signal is a weak signal, it is amplified to a signal of appropriate strength (amplitude) via the detection signal amplifier 13, and then sent to a video signal processing circuit (not shown in the figure) via, for example, an optical signal transmitter 15. figure)
The surface condition of the material is obtained as an image.

[Problems to be Solved by the Invention] In a device having such a configuration, in order to adjust the brightness of the image, etc., it is necessary to change the high voltage applied to the MCP3.
The brightness is adjusted by changing the multiplication gain of the CP or by changing the amplification gain of the detection signal amplifier 13. However, when changing the high voltage applied to the MCP 3, it is necessary to vary the voltage of the reference signal power supply 9 supplied to the error amplifier 8 and change the amplitude of the output signal of the AC low voltage power supply 4. In DC high voltage generation circuits, the output response when changing the voltage value is slow, and it takes time to stabilize.
The problem is that the multiplication gain of the MCP cannot be changed quickly.

Therefore, it is adopted to adjust the brightness by changing the amplification gain of the detection signal amplifier 13, but in such a case, the variable range of the gain is narrower than when changing the high voltage applied to the MCP 3. , the inability to perform wide-range gain adjustment is considered a problem.

The present invention provides the above-described method by mutually controlling the stabilization control of a power supply that generates a DC high voltage signal and the control of the output voltage of a high voltage control circuit to which the output DC high voltage signal of the power supply is input. The purpose of this invention is to provide a DC high voltage generator that overcomes these problems.

[Means for Solving the Problems] The present invention boosts a signal generated by an AC low-voltage power supply via a step-up transformer, converts it into a DC high-voltage signal via a rectifier boost circuit, and converts the DC high-voltage signal into a DC high-voltage signal. A DC high voltage generator that stabilizes the DC high voltage signal by supplying it to an error amplifier and comparing it with a reference signal, and controlling the amplitude of the output signal of the AC low voltage power supply using the output signal of the error amplifier, The DC high voltage signal is supplied to a high voltage control circuit constituted by a semiconductor control element, the output voltage of the high voltage control circuit is supplied to a second error amplifier, and is compared with a second reference signal. The output signal of the control circuit is stabilized by the output signal of the error amplifier, and the first reference signal and the second reference signal can be changed in relation to each other.

[Function] The present invention supplies a DC high voltage signal to an error amplifier, compares it with a reference signal, and controls the amplitude of the output signal of an AC low voltage power supply using the output signal of the error amplifier to stabilize the DC high voltage signal. At the same time, the DC high voltage signal is supplied to a high voltage control circuit constituted by a semiconductor control element, and the output voltage of the high voltage control circuit is supplied to a second error amplifier and compared with a second reference signal. , the output signal of the control circuit is stabilized by the output signal of the second error amplifier, and the first reference signal and the second reference signal are varied in relation to each other.

[Example] Hereinafter, an example of the present invention will be described based on the drawings. 1st
The figure is an apparatus configuration diagram for explaining one embodiment of the present invention. In FIG. 1, the same components as in FIG. 2 are given the same numbers.

The difference between the embodiment shown in FIG. 1 and the conventional example is 2. The output (DC high voltage signal) of the rectifier booster circuit 6 is supplied to a high voltage control circuit 20 constituted by semiconductor control elements. The output voltage is applied to the MCP 3, and the second reference signal power source 23 is generated by supplying the output voltage of the high voltage control circuit 20 to the second error amplifier 22.
The output signal of the control circuit 20 is stabilized by the output signal of the second error amplifier 22, and
A first reference signal for controlling the output signal of the AC low-voltage power supply 4. be.

In the above configuration, the Kotscroft-Walton circuit 6
The DC high voltage signal obtained as the output is stabilized to a value corresponding to the reference signal from the reference signal power source 9 by feedback control by the error amplifier 8, as already explained using FIG. Furthermore, the DC high voltage signal is supplied to a high voltage control circuit 20 constituted by a semiconductor control element, such as a power transistor, and the controlled voltage is applied to the MCP 3 via the circuit. Further, the output voltage of the high voltage control circuit 20 is detected via a voltage detection resistor 21 and supplied to a second error amplifier 22. Then, the output signal of the high voltage control circuit is controlled by a signal obtained by comparing the voltage value of the second reference signal power supply 23 and the detection voltage in the error amplification '522 and amplifying the output signal in the level shift circuit 24. Ru. Further, the voltage value of the second reference signal power source 23 and the voltage value of the first reference signal power source 9 are changed in relation to each other.

By the way, the maximum output voltage value of the high voltage control circuit 20 is I
KV, the output voltage of the Kotscroft-Walton circuit 6 is IKV plus alpha, for example 1. It is about IKV. (The output of both the first reference voltage power supply and the second reference voltage power supply is maximum.) From this state, the voltage value of the second reference voltage power supply 23 is changed to control the output signal of the high voltage control circuit 20. When controlling in a wide range from IKV to several tens of volts, unless the voltage value of the second reference signal power source 23 and the voltage value of the first reference signal power source 9 are changed in relation to each other, the Cottcroft-Walton circuit 6 The output voltage is 1. Since the voltage remains at IKV, the power consumption in the high voltage control circuit 20 increases as the output signal of the high voltage control circuit 20 is decreased. Therefore, the power transistor and the like of the high voltage control circuit 20 may be damaged. Therefore, if the voltage value of the second reference signal power supply 23 and the voltage value of the first reference signal power supply 9 are changed in relation to each other, for example, the output signal of the high voltage control circuit is controlled to about 200V. , the output voltage of Kotscroft-Walton circuit 6 is 200V.
The voltage value of the reference signal power supply 9 supplied to the first error amplifier 8 is changed so that it becomes plus alpha, for example, about 220V.

In addition, when changing the output voltage of the high voltage control circuit 20 within a narrow range of several volts to several tens of volts, the basic signal voltage i! supplied to the first error amplifier 8 is changed. The voltage value of 7.9 does not necessarily need to be changed, and may be changed stepwise for each output voltage change width.

[Effects of the Invention] As is clear from the above description, according to the present invention, a DC high voltage signal is supplied to an error amplifier and compared with a basic school signal,
controlling the amplitude of the output signal of the AC low voltage power supply with the output signal of the error amplifier to stabilize the DC high voltage signal;
supplying the DC high voltage signal to a high voltage control circuit constituted by a semiconductor control element; supplying the output voltage of the high voltage control circuit to a second error amplifier and comparing it with a second reference signal;
By stabilizing the output signal of the control circuit with the output signal of the second error amplifier, the output of the rectifier booster circuit (DC high voltage signal) is stabilized by controlling only the output of the AC low voltage power supply. It is possible to realize a highly stabilized DC high voltage generator with a faster output response when changing the voltage value than in the past. Furthermore, by changing the first reference signal and the second basic signal in relation to each other, even when the output voltage of the high voltage control circuit is varied over a wide range, power consumption in the circuit can be reduced. Therefore, the semiconductor control elements etc. are not damaged.

[Brief explanation of the drawing]

FIG. 1 is an apparatus configuration diagram for explaining an embodiment of the present invention, and FIG. 2 is a diagram for explaining a conventional example. 1: Charged particle beam 2: Material 3: MCP 4: AC low voltage power supply 5: Step-up transformer 6: Rectifier step-up circuit 7: Voltage detection resistor 8: First error amplifier 9: First reference signal power supply 10: MCP entrance surface electrode 11: MCP exit surface electrode 12 near node electrode 13: Detection signal amplifier 14:
Amplifier power supply 15: Optical signal transmitter 20: High voltage control circuit 21: Voltage detection resistor 22: Second error amplifier 23: Second reference signal power supply

Claims (1)

[Claims] The signal generated by the AC low-voltage power supply is boosted through a step-up transformer, converted to a DC high-voltage signal through a rectifier booster circuit, and the DC high-voltage signal is supplied to an error amplifier to compare it with a reference signal and calculate the error. In a DC high voltage generator that stabilizes a DC high voltage signal by controlling the amplitude of the output signal of the AC low voltage power supply using an output signal of an amplifier, the DC high voltage signal is configured by a semiconductor control element. The output voltage of the high voltage control circuit is supplied to a second voltage control circuit.
The output signal of the control circuit is stabilized by the output signal of the second error amplifier, and the output signal of the control circuit is stabilized by the output signal of the second error amplifier. A DC high voltage generator characterized in that the DC high voltage generator can vary in relation to each other.