Electrical quantity measurement device
First Claim
1. A device for measuring an electrical quantity of a system under measurement, comprising:
- a Hall element equipped with a pair of current input terminals and a pair of voltage output terminals, four equivalent resistances being formed between two adjacent terminals of said current input terminals and said voltage output terminals;
magnetic field applying means for applying a magnetic field proportional to a value of a first current on said Hall element;
current supply means for flowing a second current between said pair of said current input terminals of said Hall element;
output means for detecting a first voltage appearing between said pair of said output voltage terminals and outputting said first voltage as a measured value corresponding to said electrical quantity;
offset compensation means for detecting an offset appearing between said pair of said voltage output terminals for varying one of said four equivalent resistances in said Hall element based on said offset thus detected so as to compensate said offset; and
input resistance control means for varying remaining three of said equivalent resistances other than said one equivalent resistance such that a second voltage generated between said pair of said current input terminals caused by a flow of said second current is maintained at a predetermined value;
whereby an input resistance value of said Hall element being held constant.
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Accused Products
Abstract
A device for measuring an electrical quantity of a system under measurement including a Hall element equipped with a pair of current input terminals and a pair of voltage output terminals. In the Hall element, four equivalent resistances are formed. The device also includes a device for applying a magnetic field proportional to a value of a first current on the Hall element, and a current supply circuit for flowing a second current between the current input terminals. The device further includes an output circuit for detecting a first voltage appearing between the output voltage terminals and outputting the first voltage as a measured value corresponding to the electrical quantity, and an offset compensation circuit for detecting an offset appearing between the voltage output terminals for varying one of the four equivalent resistances based on the offset thus detected so as to compensate the offset. The device also includes an input resistance control circuit for varying remaining three of the equivalent resistances such that a second voltage generated between the current input terminals caused by a flow of the second current is maintained at a predetermined value. An input resistance value of the Hall element is thereby held constant.
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Citations
7 Claims
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1. A device for measuring an electrical quantity of a system under measurement, comprising:
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a Hall element equipped with a pair of current input terminals and a pair of voltage output terminals, four equivalent resistances being formed between two adjacent terminals of said current input terminals and said voltage output terminals; magnetic field applying means for applying a magnetic field proportional to a value of a first current on said Hall element; current supply means for flowing a second current between said pair of said current input terminals of said Hall element; output means for detecting a first voltage appearing between said pair of said output voltage terminals and outputting said first voltage as a measured value corresponding to said electrical quantity; offset compensation means for detecting an offset appearing between said pair of said voltage output terminals for varying one of said four equivalent resistances in said Hall element based on said offset thus detected so as to compensate said offset; and input resistance control means for varying remaining three of said equivalent resistances other than said one equivalent resistance such that a second voltage generated between said pair of said current input terminals caused by a flow of said second current is maintained at a predetermined value; whereby an input resistance value of said Hall element being held constant. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification