Charged Particle Beam Control Circuit Ground Potential Stabilization
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Solution Overview
Problem
In charged particle beam control devices, variations in ground potential lead to changes in the current flowing through deflection coils, affecting the irradiation accuracy of electron beams, which is not adequately addressed by existing solutions.
Innovation Solution
A charged particle beam control device with a current control circuit that includes a current conversion unit, differential amplification unit, and correction unit to stabilize the current flowing through the deflection coils by adjusting the current based on control signals and compensating for ground potential variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If constant current circuits are formed on one substrate to reduce device size and cost, then device size and cost are reduced, but ground potential variation occurs due to return current flowing through the ground
Solution Approach 1:
The invention divides the ground reference into multiple independent ground terminals (first ground terminal and second ground terminal) within the constant current circuit. This segmentation allows the circuit to reference different ground potentials at different points, preventing ground potential variation from affecting the current control accuracy while maintaining a compact single-substrate design.
2Reliability
If ground potential is stabilized by applying constant operation voltage to load circuit, then ground potential variation is prevented, but irradiation accuracy of electron beam deteriorates due to variation in relationship between control signal and output current
Solution Approach 1:
The invention introduces a feedback mechanism where the control signal is fed back through a feedback resistor to the inverting input terminal of the operational amplifier. This feedback loop automatically compensates for ground potential variations by adjusting the output current to maintain the correct relationship between control signal and actual current, thereby preserving irradiation accuracy while allowing ground potential stability measures to be taken.
3Device complexity
If multiple constant current circuits are integrated on one substrate, then device size is reduced, but current control precision deteriorates due to ground potential variation affecting control signal relationship
Solution Approach 1:
The invention implements local quality by providing each constant current circuit with dedicated ground terminals and feedback paths tailored to its specific requirements. This allows each circuit to maintain precise current control independent of ground potential variations, while all circuits remain integrated on the same substrate, achieving both miniaturization and precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively stabilizes the current flowing through the deflection coils, preventing deterioration in electron beam irradiation accuracy due to ground potential variations, ensuring high-resolution imaging.
Implementation Method 1
a differential amplification unit to which a voltage of a first ground side terminal of the control signal and a voltage of a second ground side terminal of the current detection resistor are input, and that outputs an output signal proportional to a voltage difference between the voltage of the first ground side terminal and the voltage of the second ground side terminal
Implementation Method 2
a correction unit to which the output signal output from the differential amplification unit and the control signal are input, and that adds the output signal to the control signal at a predetermined ratio
Implementation Method 3
A deflection coil that deflects a charged particle beam by a magnetic field is used in a charged particle beam control device
Data Source
AI summary
In a charged particle beam control device, irradiation accuracy of an electron beam can be prevented from deteriorating due to a variation in a ground potential. A current control circuit (1) includes a current conversion unit (4) that supplies a constant current (Id) by adjusting an amount of a current flowing through a current detection resistor (R1) based on a control signal (V1), a differential amplification unit (5) to which a voltage of a first ground side terminal (G1) of the control signal and a voltage of a second ground side terminal (G2) of the current detection resistor (R1) are input, and that outputs an output signal (V3) proportional to a voltage difference between the voltage of the first ground side terminal (G1) and the voltage of the second ground side terminal (G2), and a correction unit (6) to which the output signal (V3) output from the differential amplification unit (5) and the control signal (V1) are input, and that adds the output signal (V3) to the control signal (V1) at a predetermined ratio.