# US 2008/0304201 A1 · Voltage signal converter circuit and motor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2008/0304201 A1 - Document ID: US20080304201A1 - Status: Published application - Kind: A1 - Application number: 12/134,461 - Filed: 2008-06-06 - Published: 2008-12-11 - Earliest claimed: 2007-06-08 - Assignees: Nidec Corporation - Inventors: Nobuhiro Takao; Tsuneki Takagi - Web page: https://patentgrep.com/patent/US20080304201A1 ## CPC - G01P 3/489: Digital circuits therefor - G01P 3/487: delivered by rotating magnets - G01P: MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT (measuring or recording blood flow A61B5/02, A61B8/06; monitoring speed or deceleration of electrically-propelled vehicles B60L3/00; vehicle lighting systems adapted to indicate speed B60Q1/54; determining position or course in navigation, measuring ground distance in geodesy or surveying G01C; combined measuring devices for measuring two or more variables of movement G01C23/00; measuring velocity of sound G01H; measuring velocity of light G01J7/00; measuring direction or velocity of solid objects by reception or emission of radiowaves or other waves and based on propagation effects, e.g. Doppler effect, propagation time, direction of propagation, G01S; measuring speed of nuclear radiation G01T; measuring acceleration of gravity G01V; {measuring or recording the speed of trains B61L23/00; speed indicators incorporated in motor vehicles B60K35/00; measuring frequency or phase G01R; traffic control G08G}) ## Abstract In a voltage signal converter circuit, a peak hold circuit, which is configured with an operational amplifier, a diode, and a capacitor, receives a sensor voltage signal and outputs a peak voltage signal. A bottom hold circuit, which is configured with an operational amplifier, a diode, and a capacitor, receives a sensor voltage signal and outputs a bottom voltage signal. An intermediate voltage signal generator circuit receives the peak voltage signal and the bottom voltage signal and generates an intermediate voltage signal having an intermediate value between a peak voltage value and a bottom voltage value. A comparator generates an accurate rectangular wave voltage signal having a duty ratio equal to 50% in accordance with a magnitude correlation between a sensor voltage value and an intermediate voltage value. ## Claims ### Claim 1 A voltage signal converter circuit arranged to receive, from a magnetoresistive sensor arranged to sense a magnetic field generated by a magnet having a plurality of magnetic poles, a sensor voltage signal in accordance with a variation in the magnetic field due to a variation in a relative position between the magnet and the magnetoresistive sensor to convert the sensor voltage signal to a rectangular wave voltage signal, the voltage signal converter circuit comprising: a peak hold circuit arranged to adopt a maximum of a voltage value of the sensor voltage signal input from the magnetoresistive sensor and output a peak voltage signal having a voltage value equal to the maximum; a bottom hold circuit arranged to adopt a minimum of the voltage value of the sensor voltage signal input from the magnetoresistive sensor and output a bottom voltage signal having a voltage value equal to the minimum; an intermediate voltage signal generator circuit arranged to output an intermediate voltage signal having a voltage value equal to an average between the voltage value of the peak voltage signal input from the peak hold circuit and the voltage value of the bottom voltage signal input from the bottom hold circuit; and a rectangular wave voltage signal generator circuit arranged to output the rectangular wave voltage signal in accordance with a magnitude correlation between the voltage value of the sensor voltage signal input from the magnetoresistive sensor and the voltage value of the intermediate voltage signal input from the intermediate voltage signal generator circuit. ### Claim 2 (depends on 1) The voltage signal converter circuit according to claim 1, wherein the peak hold circuit includes: a calculation amplifier arranged to receive the sensor voltage signal at a non-inverting input terminal; a rectifier arranged to set a direction of rectification at a negative feedback portion of the calculation amplifier to a forward direction with respect to a direction of input to an inverting input terminal; and a capacitor arranged to accumulate electric charges in correspondence with the voltage value of the peak voltage signal. ### Claim 3 (depends on 1) The voltage signal converter circuit according to claim 1, wherein the bottom hold circuit includes: a calculation amplifier arranged to receive the sensor voltage signal at a non-inverting input terminal; a rectifier arranged to set a direction of rectification at a negative feedback portion of the calculation amplifier to a backward direction with respect to a direction of input to an inverting input terminal; and a capacitor arranged to accumulate electric charges in correspondence with the voltage value of the bottom voltage signal. ### Claim 4 (depends on 1) The voltage signal converter circuit according to claim 1, wherein the intermediate voltage signal generator circuit includes a voltage divider circuit having two resistors which have resistance values equal to each other and are connected in series, and the voltage divider circuit includes: an input unit arranged to receive the peak voltage signal at a first input terminal; an input unit arranged to receive the bottom voltage signal at a second input terminal; and an output unit arranged to output the intermediate voltage signal at a connection point between the two resistors. ### Claim 5 (depends on 1) The voltage signal converter circuit according to claim 1, wherein the rectangular wave voltage signal generator circuit includes a comparator circuit arranged to compare the voltage value of the sensor voltage signal with the voltage value of the intermediate voltage signal, and the comparator circuit includes: an input unit arranged to receive the sensor voltage signal at a first input terminal; an input unit arranged to receive the intermediate voltage signal at a second input terminal; and an output unit arranged to output the rectangular wave voltage signal at an output terminal. ### Claim 6 (depends on 1) The voltage signal converter circuit according to claim 1, further comprising: a voltage value decreasing unit arranged to decrease the voltage value of the peak voltage signal; and a voltage value increasing unit arranged to increase the voltage value of the bottom voltage signal. ### Claim 7 (depends on 6) The voltage signal converter circuit according to claim 6, wherein the voltage value decreasing unit includes a control unit arranged to control the voltage value such that a speed of decrease in the voltage value of the peak voltage signal due to a variation in temperature is larger than a speed of increase in the voltage value of the peak voltage signal. ### Claim 8 (depends on 6) The voltage signal converter circuit according to claim 6, wherein the voltage value increasing unit includes a control unit arranged to control the voltage value such that a speed of increase in the voltage value of the bottom voltage signal due to a variation in temperature is larger than a speed of decrease in the voltage value of the bottom voltage signal. ### Claim 9 (depends on 2) The voltage signal converter circuit according to claim 2, further comprising a voltage value decreasing unit arranged to decrease the voltage value of the peak voltage signal, wherein the voltage value decreasing unit includes a decreasing unit arranged to decrease the voltage value of the peak voltage signal by discharging electric charges from the capacitor to an end having a voltage value smaller than the voltage value of the peak voltage signal. ### Claim 10 (depends on 9) The voltage signal converter circuit according to claim 9, wherein the end having a smaller voltage includes an end from which the bottom voltage signal is output. ### Claim 11 (depends on 9) The voltage signal converter circuit according to claim 9, wherein the end having a smaller voltage includes an end applied with a voltage having a voltage value smaller than the voltage value of the bottom voltage signal. ### Claim 12 (depends on 9) The voltage signal converter circuit according to claim 9, wherein the voltage value decreasing unit includes a control unit arranged to control the voltage value such that a speed of decrease in the voltage value of the peak voltage signal due to a variation in temperature is larger than a speed of increase in the voltage value of the peak voltage signal. ### Claim 13 (depends on 3) The voltage signal converter circuit according to claim 3, further comprising a voltage value increasing unit arranged to increase the voltage value of the bottom voltage signal, wherein the voltage value increasing unit includes an increasing unit arranged to increase the voltage value of the bottom voltage signal by charging electric charges to the capacitor from an end having a voltage value larger than the voltage value of the bottom voltage signal. ### Claim 14 (depends on 13) The voltage signal converter circuit according to claim 13, wherein the end having a larger voltage includes an end from which the peak voltage signal is output. ### Claim 15 (depends on 13) The voltage signal converter circuit according to claim 13, wherein the end having a larger voltage includes an end applied with a voltage having a voltage value larger than the voltage value of the peak voltage signal. ### Claim 16 (depends on 13) The voltage signal converter circuit according to claim 13, wherein the voltage value increasing unit includes a control unit arranged to control the voltage value such that a speed of increase in the voltage value of the bottom voltage signal due to a variation in temperature is larger than a speed of decrease in the voltage value of the bottom voltage signal. ### Claim 17 (depends on 1) A motor comprising the voltage signal converter circuit according to claim 1.