# US 5,705,908 A · Drive unit and a motor drive control method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,705,908 A - Document ID: US5705908A - Status: Granted - Kind: A - Application number: 08/670,822 - Filed: 1996-06-25 - Granted: 1998-01-06 - Earliest claimed: 1995-06-27 - Assignees: NEC Corporation - Inventors: Hideo Kashimura - Web page: https://patentgrep.com/patent/US5705908A ## CPC - H02P 8/40: Special adaptations for controlling two or more stepping motors - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS ## Abstract A drive unit capable of maintaining the stability of driving speed with respect to the driven part in which the motor is not used at a low drive efficiency. Said drive unit comprises the first and second stepping motors 12 and 14 transmitting power to the driven part at a rated driving output corresponding to the load torque of said driven part, the first and second motor drive control units 15 and 16 supplying electric power to these first and second stepping motors 12 and 14 and controlling their drive, a temperature detection circuit 7 detecting the temperature of the heat generated by these first and second motor drive control units 15 and 16 and outputting temperature detection signals, and a system control circuit 3 switching the allocation of the main drive unit or the auxiliary drive unit based on the temperature detection signals outputted from the allocation and temperature detection circuit 7 allocating one of the first or second stepping motors 12 or 14 to serve as the main drive unit or the auxiliary drive unit when the detected temperature has exceeded the previously set reference temperature. ## Claims ### Claim 1 A drive unit operable to drive a driven part comprising: a first and a second stepping motor for transmitting power corresponding to a load torque of the driven part to the driven part; a first and a second motor control unit for respectively supplying electric power to said first and second stepping motors and for respectively controlling a driving operation of said first and second stepping motors; a speed detection circuit for detecting a driving speed of the driven part and for outputting speed detection signals; a temperature detection section for detecting a temperature generated by each of said first and second motor control units and for outputting temperature detection signals; and a system control circuit for determining a driving output of said first and second motor control units based on the speed detection signals output by said speed detection circuit for allocating one of said first and second stepping motors as a main drive unit and the other of said first and second stepping motors as an auxiliary drive unit, wherein a driving output of said auxiliary drive unit is modified according to said speed detection signals, and for switching an allocation of said first and second stepping motors as said main drive unit and said auxiliary drive unit based on the temperature detection signals output from said temperature detection section when the temperature of one of said first and second motor drive control units exceeds a reference temperature. ### Claim 2 (depends on 1) The drive unit as described in claim 1 in which said system control circuit further sets a power level supplied to one of the first and second stepping motors functioning as said auxiliary drive unit, said system control circuit raising the power level by equal increments up to a maximum value which corresponds to a power level supplied to the other of said first and second stepping motors. ### Claim 3 (depends on 1) The drive unit as described in claim 1 in which said system control circuit sets a minimum power level supplied to one of the first and second stepping motors functioning as said auxiliary drive unit at a power level that produces no burden on the other of said first and second stepping motors functioning as the main drive unit. ### Claim 4 A motor drive control method for a drive unit including a first and second stepping motor for transmitting power to a driven part with a rated driving output corresponding to a load torque of the driven part, and a first and second motor drive control unit for supplying electric power to the first and second stepping motors and for controlling driving operations thereof, wherein one of said first and second stepping motors is allocated to work as a main drive unit and the other of said first and second stepping motors is allocated as an auxiliary drive unit, said control method comprising: detecting a driving speed of the driven part and modifying a driving output to one of the first and second stepping motors functioning as said auxiliary drive unit based on said detected driving speed, and detecting a temperature of each of said first and second motor drive control units and switching an allocation of said first and second stepping motors as the main drive unit and the auxiliary drive unit when the detected temperature of one of the first and second motor drive control units exceeds a reference temperature. ### Claim 5 (depends on 4) The motor drive control method as described in claim 4 further comprising: setting a level of electric power supplied to one of the first and second stepping motors functioning as said auxiliary drive unit such that said level may rise by equal increments up to a maximum level represented by a power level supplied to the other one of the first and second stepping motors functioning as the main drive unit. ### Claim 6 (depends on 4) The motor drive control method as described in claim 4 further comprising: setting a minimum level of electric power supplied to one of the first and second stepping motors functioning as said auxiliary drive unit at a level of electric power that does not produce a burden on the other of said first and second stepping motors allocated as said main drive unit. ### Claim 7 A drive unit operable to drive a driven part comprising: a first and a second stepping motor for transmitting power corresponding to a load torque of the driven part to the driven part; a first and a second motor control unit for respectively supplying electric power to said first and second stepping motors; a speed detection circuit for detecting a driving speed of the driven part and outputting a speed detection signal; and a system control circuit for allocating one of said first and second stepping motors as a main drive unit and the other of said first and second stepping motors as an auxiliary drive unit, and for modifying a driving output of said auxiliary drive unit according to said speed detection signal. ### Claim 8 (depends on 7) The drive unit of claim 7, wherein said first and second stepping motors are disposed on a common shaft. ### Claim 9 (depends on 8) The drive unit of claim 8, in which said system control circuit further sets a power level supplied to one of the first and second stepping motors functioning as said auxiliary drive unit, said system control circuit raising the power level by equal increments up to a maximum value which corresponds to a power level supplied to the other of said first and second stepping motors. ### Claim 10 (depends on 8) The drive unit of claim 8, in which said system control circuit sets a minimum power level supplied to one of the first and second stepping motors functioning as said auxiliary drive unit at a power level that produces no burden on the other of said first and second stepping motors functioning as the main drive unit.