Speed control for orbital shaker with reversing mode
First Claim
1. A microprocessor based controller for a direct drive DC motor, comprising:
- a microprocessor having at least one input port for receiving digital data, at least one output port for generating digital data, and at least one interrupt line for receiving periodic pulses which cause an interruption of normal program execution sequence;
means for inputting to said input port a digital signal indicative of a desired orbital speed for said motor;
means for inputting to said interrupt line a series of pulses having a frequency indicative of the actual rotational speed of the motor;
means for calculating the actual rotational speed of the motor by calculating the time between pulses and dividing by the number of pulses per revolution of the motor;
means for comparing said actual rotational speed of the motor with said desired orbital speed and for generating a motor drive signal from said output port which is one level if the desired orbital speed is less than the actual rotational speed and another level if the desired orbital speed is greater than the actual rotational speed; and
a three-terminal device connected to said output port to receive said motor drive signal and connected to said direct drive DC motor to control a flow of electric current through said direct drive DC motor in response to said motor drive signal by turning said motor fully on in response to said one level and fully off in response to said other level.
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Accused Products
Abstract
An orbital shaker apparatus which has a tray for cyclic motion is flexibly suspended from a frame which is flexibly suspended from a plurality of stationary supports. The flexible suspension constrains the tray to move only translationally along one axis with respect to the frame and constrains the frame to move only translationally along one axis perpendicular to the tray movement axis. A single chip microprocessor is used to scan, input store, display and control the speed, duration and control functions for the orbital motion. Embodied in the software of the microprocessor is a real-time closed loop speed control which monitors the actual speed of the orbital motion thru an interrupt facility by calculating the duration of pulses received from an optoelectric sensor. The measured pulse duration is digitally compared to the desired duration and a digital control signal is provided to drive a DC motor which is directly coupled to the drive shaft which imparts the motion. A set speed mode and a reversing mode are selectable by an operator to provide different means for agitation.
79 Citations
37 Claims
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1. A microprocessor based controller for a direct drive DC motor, comprising:
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a microprocessor having at least one input port for receiving digital data, at least one output port for generating digital data, and at least one interrupt line for receiving periodic pulses which cause an interruption of normal program execution sequence; means for inputting to said input port a digital signal indicative of a desired orbital speed for said motor; means for inputting to said interrupt line a series of pulses having a frequency indicative of the actual rotational speed of the motor;
means for calculating the actual rotational speed of the motor by calculating the time between pulses and dividing by the number of pulses per revolution of the motor;means for comparing said actual rotational speed of the motor with said desired orbital speed and for generating a motor drive signal from said output port which is one level if the desired orbital speed is less than the actual rotational speed and another level if the desired orbital speed is greater than the actual rotational speed; and a three-terminal device connected to said output port to receive said motor drive signal and connected to said direct drive DC motor to control a flow of electric current through said direct drive DC motor in response to said motor drive signal by turning said motor fully on in response to said one level and fully off in response to said other level. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A speed control for a direct drive DC motor, comprising:
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a microprocessor having a control program for execution, at least one input port for receiving digital data, at least one output port for generating digital data, and at least one interrupt line for receiving interrupt signals which cause an interruption of normal control program execution; means for generating an interrupt signal upon a predetermined increment of angular rotation of the motor; means for inputting to said input port digital data indicative of a desired speed for the motor; a high speed clock producing a frequency signal divided into many small time increments; said control program including means for converting said desired speed data into the number of time increments of said high speed clock that would occur in said predetermined increment of angular rotation of the motor if it ware being operated at said desired speed and means for storing said desired speed number; interrupt program means for counting the number of time increments of said high speed clock between interrupt signals such that a value indicative of the actual speed of the motor is calculated every predetermined increment of angular rotation; means for comparing said actual speed value with said desired speed value; means for generating a motor drive signal from said output port which is one level if the desired speed value is less than the actual speed value and another level if the desired speed value is greater than the actual speed value; and a three-terminal device connected to said output port to receive said motor drive signal and connected to said direct drive DC motor to control a flow of electric current through said direct drive DC motor in response to said motor signal by turning said motor fully on in response to said one level of the motor drive signal and turning said motor fully off in response to said other level of the motor drive signal. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15)
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16. A speed controller for a shaker apparatus having a base, a tray for supporting articles and moveable relative to the base, drive means for effecting a predetermined cyclical motion of the tray, and suspension means for supporting the tray on the base and for providing two-axis translational movement of the tray while preventing rotation thereof, the suspension means including a plurality of flexible supports loaded in tension and substantially inflexible in predetermined directions, said speed controller comprising:
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a direct drive DC motor which is coupled to the drive means and imparts the predetermined cyclical motion by its rotation; a microprocessor having a control program for execution, at least one input port for receiving digital data, at least one output port for generating digital data, and at least one interrupt line for receiving interrupt signals which cause an interruption of normal control program execution; means for generating an interrupt signal upon a predetermined increment of angular rotation of the motor; means for inputting to said input port digital data indicative of a desired speed for the motor; a high speed clock producing a frequency signal divided into many small time increments; said control program including means for converting said desired speed data into the number of time increments of said high speed clock that would occur in said predetermined increment of angular rotation of the motor if it were being operated at said desired speed and means for storing said desired speed number; interrupt program means for counting the number of time increments of said high speed clock between interrupt signals such that a value indicative of the actual speed of the motor is calculated every predetermined increment of angular rotation; means for comparing said actual speed value with said desired speed value; means for generating a motor drive signal from said output part which is one level if the desired speed value is less than the actual speed value and another level if the desired speed value is greater than the actual speed value; and a three-terminal device connected to said output port to receive said motor drive signal and connected to said direct drive DC motor to control a flow of electric current through said direct drive DC motor in response to said motor drive signal by turning said motor fully on in response to said one level of the motor drive signal and turning said motor fully off in response to said another level of said motor drive signal. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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30. A speed controller for a shaker apparatus having a base, a tray for supporting articles and moveable relative to the base, drive means for effecting a predetermined cyclical motion of the tray, and suspension means for supporting the tray on the base and for providing two-axis translational movement of the tray while preventing rotation thereof, the suspension means including a plurality of flexible supports loaded in tension and substantially inflexible in predetermined directions, said speed controller comprising:
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a direct drive DC motor which is coupled to the drive means and imparts the predetermined cyclical motion by its rotation; a microprocessor having a control program for execution, at least one input port for receiving digital data, at least one output port for generating digital data, and at least one interrupt line for receiving interrupt signals which cause an interruption of normal control program execution; means for generating an interrupt signal upon a predetermined increment of angular rotation of the motor; means for inputting to said input port digital data indicative of a desired speed for the motor; a high speed clock producing a frequency signal divided into many small time increments; said control program including means for converting said desired speed data into the number of time increments of said high speed clock that would occur in said predetermined increment of angular rotation of the motor if it were being operated at said desired speed and means for storing said desired speed number; interrupt program means for counting the number of time increments of said high speed clock between interrupt signals such that a value indicative of the actual speed of the motor is calculated every predetermined increment of angular rotation; means for comparing said actual speed value with said desired speed value; means for generating a motor drive signal from said output port which is one level if the desired speed value is less than the actual speed value and another level if the desired speed value is greater than the actual speed value, said one level of the motor drive signal turning said motor fully on and said another level of the motor drive signal turning said motor fully off; a power supply circuit having a source terminal connected to a source of voltage and a ground terminal connected to ground; the coil of said motor being connected between said source terminal and ground terminal such that a current flows therethrough to operate said motor; control switch means connected in series with said motor coil between said source terminal and said ground terminal; said control switch means adapted to switch said motor coil on and off responsive to said control signal; means for generating a direction signal from said output port which is one level if the desired motor rotation is clockwise and another level if the desired motor rotation is counter-clockwise; and a double-pole, double-throw switch means which connects said source terminal to one terminal of said motor coil when operated in a first direction, and connects said source terminal to the other terminal of said motor when operated in a second direction, said switch means comprising a set of relay contacts connected as a double-pole, double throw switch; and
a relay coil controlled by said direction signal for changing the direction of said switch and thereby the direction of rotation of said motor.
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31. A reversing orbital shaker, comprising:
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a base; an electric motor connected to said base; a suspension system connected to said base; a table connected to said suspension system to be movably supported thereby and coupled to said electric motor to be driven thereby with respect to said base; means for sensing a rotational speed of said electrical motor and generating a motor speed signal in response thereto; means, coupled to said motor speed sensing means to receive said motor speed signal, for controlling said rotational speed of said electric motor in response to said motor speed signal; means, coupled to said controlling means, for timing said electric motor operating in a first rotary direction and generating a reversing signal when the time interval in which said electric motor operates in said first rotary direction reaches a selected amount; and means, coupled to said timing means to receive said reversing signal, for reversing a direction of rotation of said electric motor from said first rotary direction to a second rotary direction in response to said reversing signal. - View Dependent Claims (32)
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33. An orbital shaker for imparting cyclical motion to an article, comprising:
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a base; a table for carrying the article connected to said base and movable with respect to said base in a first orbital direction and in a second orbital direction opposite said first orbital direction; an electric motor connected to said table for driving said table in said first orbital direction and said second orbital direction; and a motor controller connectable to a source of electrical energy to be energized thereby and connected to said electric motor for controlling a flow of electric current to said electric motor for periodically reversing motion of said table from said first orbital direction to said second orbital direction and from said second orbital direction to said first orbital direction. - View Dependent Claims (34, 35, 36, 37)
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Specification