Patent Application
20080150982
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1. Field of the Invention
This disclosure relates to motor detection and control and, more particularly, to printer motor detection and control for use in a modular printer system.
2. Description of the Related Art
A printer may include modular components that may be interchangeable with other printers. For example, a laser printer may include a fuser packaged as a customer replaceable unit (CRU) that can be installed in other laser printers. The CRU may include a fuser motor to drive the fuser mechanism. While the overall operation of the CRU may be similar when switched to another printer, control of the fuser motor may differ between printers. Likewise, the fuser motor may be changed within a given CRU package such that, when used interchangeably with different laser printers, may present motor control problems.
An aspect of the present disclosure relates to a printer. The printer may include a motor and a print engine. The print engine may be configured to generate a first motor voltage and a second motor voltage, detect a first motor speed of the motor corresponding to the first motor voltage and a second motor speed of the motor corresponding to the second motor voltage. In addition, the print engine may be configured to determine at least one physical characteristic of the motor based on, at least in part, the first motor speed and the second motor speed. Furthermore, the print engine may be configured to control the operation of the motor based on, at least in part, at least one physical parameter of the motor.
Another aspect of the present disclosure relates to a method for determining a motor type installed in a printer. The method may include generating a first printer motor voltage and a second printer motor voltage and supplying the first printer motor voltage and the second printer motor voltage to a printer motor. The method may also include detecting a first printer motor speed corresponding to the first printer motor voltage and a second printer motor speed corresponding to the second printer motor voltage. Furthermore the method may include determining at least one physical characteristic of the printer motor based on, at least in part, the first motor speed and the second motor speed and controlling the operation of the printer motor based on, at least in part, the at least one physical parameter of the printer motor.
A further aspect of the present disclosure relates to an article comprising a storage medium having stored thereon instructions that when executed by a machine result in generating a first printer motor voltage and a second printer motor voltage and supplying the first printer motor voltage and the second printer motor voltage to a printer motor. In addition, the instructions stored thereon when executed by a machine may also result in detecting a first printer motor speed corresponding to the first printer motor voltage and a second printer motor speed corresponding to the second printer motor voltage. Furthermore, the instructions stored thereon when executed by a machine may also result in determining at least one physical characteristic of the printer motor based on, at least in part, the first motor speed and the second motor speed and controlling the operation of the printer motor based on, at least in part, the at least one physical parameter of the printer motor.
Features and advantages of the claimed subject matter will be apparent from the following detailed description of embodiments consistent therewith, which description should be considered with reference to the accompanying drawings, wherein:
Although the following Detailed Description will proceed with reference being made to illustrative embodiments, many alternatives, modifications, and variations thereof will be apparent to those skilled in the art.
Print engine 102 may include printer controller circuitry 104, memory 106 and motor driver circuitry 108. In one embodiment, memory 106 may be configured to store at least one control code set corresponding to the fuser motor 124. When executed by printer controller circuitry 104, the control code set may permit printer controller circuitry 104 to control the operation of the fuser motor 124. In this embodiment, memory 106 may be configured to store a first control code set 134 corresponding to a first type of fuser motor 124 and a second control code set 136 corresponding to second type of fuser motor 124. Based upon the type of fuser motor disposed within the CRU 120, the print engine 102 may select the appropriate control code set to control the operation of the fuser motor. “Control code set” may include, for example, one or more instructions that when executed by the printer controller circuitry 104 cause the print engine 102 to control the fuser motor 124.
Motor driver circuitry 108 may include pulse width modulation (PWM) circuitry 110. The pulse width modulation circuitry 110 may operate as DC to DC converter circuitry to generate a variable fuser motor DC power supply (Vm) based on a printer power supply 130 (Vs). As is understood in the art, PWM circuitry 110 may include at least one controllable switch (not shown). The duty cycle (p) of the at least one controllable switch may dictate the value (magnitude) of the DC power (Vm) generated by the motor driver circuitry 108. To that end, printer controller circuitry 104 may be configured to command the motor driver circuitry 108 to adjust the duty cycle of the PWM circuitry 110 to control the supply voltage Vm of the fuser motor 124. In addition, PWM circuitry 110 may be configured to control the value of Vm based on, at least in part, feedback information received from the fuser motor 124. For example, in this embodiment, fuser motor speed information (ω) 132 may be used by PWM circuitry 110 in a “closed-loop” manner to control the supply voltage Vm, which, in turn may be used to control the speed (ω) of the fuser motor 124.
In one embodiment, motor speed sensor circuitry 126 may include an optical rotational sensor (not shown) configured to sense rotation of a shaft of the fuser motor 124. Of course, motor speed sensor circuitry 126 may include other electrical and/or electro-mechanical rotational sensors, for example, capacitive rotational sensors, etc. As stated, motor speed sensor circuitry 126 configured to generate a signal (ω) indicative of, or proportional to, the speed (RPM) of the fuser motor 124. To that end, motor speed sensor circuitry 126 may include analog-to-digital circuitry configured to convert an analog signal generated by a rotational sensor to a digital signal, for example, a digital pulse train indicative of, or proportional to the motor speed ω.
In addition, printer controller circuitry 104 may be configured to detect at least one physical parameter of the fuser motor 124. A “physical parameter”, as used herein with respect to the fuser motor 124, may include, for example, torque constant, back-EMF constant, winding resistance, rotor inertia, and/or other detectable parameter associated with the motor 124. For example, in one embodiment, if print engine 102 senses that a new CRU 120 has been placed into slot 129 (via for example, a mechanical, electrical and/or electro-mechanical switch, not shown), the printer controller circuitry 104 may execute a detection operation to determine one or more physical parameters of the fuser motor 124. Alternatively or additionally, upon power-up or reset initialization of the print engine 102, the printer controller circuitry 104 may execute a detection operation to determine one or more physical parameters of the fuser motor 124.
The voltage, Vm, generated by print engine 102 and supplied to the fuser motor 124, may be represented by:
Vm=(KE*ω)+((Tg/KT)*R); EQ. 1
where:
KE is the motor back-EMF constant (V-sec/rad), ω is the motor speed (rad/sec), Tg is the total torque generated by the fuser motor (N−m), KT is the motor torque constant (N−m/A) and R is the fuser motor resistance (Ohms).
The total torque generated by the fuser motor 124 may be represented by:
T
g
=T
L
+T
a
+T
f
+T
D; EQ: 2
where:
TL is the load torque (N−m) of the fuser motor, Ta is the acceleration torque (N−m) of the fuser motor, Tf is the friction torque (N−m) of the fuser motor and TD is the damping torque (N−m) of the fuser motor.
In one embodiment, printer controller circuitry 104 may command motor driver circuitry 108 to control the fuser motor 124 in a steady state mode so that the acceleration torque Ta is approximately zero. Furthermore, printer controller circuitry 104 may command motor driver circuitry 108 to control the fuser motor 124 to spin in both forward and reverse directions. The forward direction may engage the fuser 122 and/or one or more mechanical rollers (not shown) associated with the CRU 120. The reverse direction, referred to herein as the duplex direction, may disengage the fuser motor 124 from the fuser 122 and/or from one or more mechanical rollers (not shown) associated with the CRU 120, and thus, the damping loads on the motor 124 may be negligible. Accordingly, printer controller circuitry 104 may command motor driver circuitry 108 to control the fuser motor 124 to spin in a duplex direction, and as a result, the damping torque, TD, may be assumed to be approximately zero. “Approximately zero” may be generally defined as a value near zero or a negligible value (e.g., within engineering tolerances of the components of
As stated above, PWM circuitry 110 may adjust the duty cycle of the supply voltage 130 (Vs) to adjust the fuser motor voltage Vm. The duty cycle may be adjusted between, for example a minimum duty cycle of 0% and a maximum duty cycle of 100%. This range may be linearly segmented and represented by an arbitrary numeric scale, for example, 0 through z, where 0 represents a 0% duty cycle, z represents a 100% duty cycle and z/2 represents a 50% duty cycle. Of course, as stated, this is an arbitrary scale and any numeric range (as may be implemented by motor driver circuitry 108) may be used without departing from this embodiment. Thus, the fuser motor voltage Vm may also be represented by:
Vm=Vs*(p/P)−VD; EQ. 3
where:
p is the PWM setting from 0 to z, P is the maximum PWM setting (z) and VD is the voltage drop associated with motor driver circuitry 108. Depending on the type and efficiency of motor driver circuitry 108 used, in certain embodiments, the voltage drop (VD) of the motor driver circuitry may be assumed to be approximately zero. Alternatively, for typical motor driver circuitry 108 operating at a duty cycle of less than 90% maximum, the voltage drop (VD) of the motor driver circuitry may be assumed to be approximately constant.
Combining Equations 1, 2 and 3:
Vs*(p/P)−VD=(KE*ω)+(((TL+TE)/KT)*R) EQ. 4
Equation 4 can be rearranged to solve for motor speed ω, as follows:
ω=(Vs/(KE*P))*p−(VD/KE)−((TL+Tf)/(KE*KT))*R EQ. 5
Equation 5 may represent the equation of a straight line, where (Vs/(KE*P)) is the slope and (VD/KE)−((TL+Tf)/(KE*KT))*R is the y-intercept. Accordingly, the slope of Equation 5 may be measured by using two different PWM values (e.g., p1 and p2) and measuring the corresponding motor speed values (e.g., ω1 and ω2).
The following example is directed to detection of a back-EMF constant of the fuser motor 124. The back-EMF constant may be indicative of the type and/or size of the fuser motor 124. Accordingly, detection of back-EMF may enable the print engine to determine the type of fuser motor 124 being used, and thus, implement a control process corresponding to the type of fuser motor.
The slope of Equation 5 may be equated with the detected speed and PWM duty cycle settings, as follows:
(Vs/(KE*P))=(ω2−ω1)/(p2−p1) EQ. 6
Equation 6 can be rearranged to solve for the back-EMF constant KE, as follows:
K
E=((p2−p1)/(ω2−ω1))*(Vs/P) EQ. 7
Since the supply voltage Vs and the maximum duty cycle P that may be generated by PWM circuitry 110 may be known, printer controller circuitry 104 may be configured to generate the back-EMF value, KE, based on the PWM settings p1 and p2 and the measured motor speed values ω1 and ω2. Based on the back-EMF value, printer controller circuitry 104 may select an appropriate control code set for the type of fuser motor 124 disposed within the CRU 120. To that end, memory 106 may include a look-up table (not shown) that correlates back-EMF values with a control code set, and printer controller circuitry 104 may select a control code set to control the fuser motor 124 by reading the appropriate control set in the look-up table. Of course, a look-up table is only an example of correlating a detected physical parameter (e.g., back-EMF) to an appropriate control code set (e.g., 134 and/or 136) to control the motor 124.
In the previous example, the value of Vs 130 may be assumed constant or within a tolerance range. This may present detection problems, especially in the overlap region 412. Vs 130 may represent a generic power supply associated with the printer system 100, and may vary base on, for example, load conditions. Accordingly, in an alternative embodiment, the power supply Vs 130 may be measured to provide a more accurate value of the power supply voltage. This may enable, for example, a more accurate back-EMF calculation. Thus, and referring again to
Accordingly, Equation 7 may be rewritten to reflect a measured value of the power supply 130.
K
E=((p2−p1)/(ω2−ω1))*(Vs′/P) EQ. 8
Using Vs′ may improve the separation between motors having similar back-EMF values (as described in
While the foregoing description of
The operative components of the print engine 102 of
As used in any embodiment described herein, “circuitry” may comprise, for example, singly or in any combination, hardwired circuitry, programmable circuitry, state machine circuitry, and/or firmware that stores instructions executed by programmable circuitry. Any of the operations and/or operative components described in any embodiment herein may be implemented in software, firmware, hardwired circuitry and/or any combination thereof.
Embodiments of the methods described above may be implemented in a computer program that may be stored on a storage medium having instructions to program a system (e.g., a machine) to perform the methods. The storage medium may include, but is not limited to, any type of disk including floppy disks, optical disks, compact disk read-only memories (CD-ROMs), compact disk rewritables (CD-RWs), and magneto-optical disks, semiconductor devices such as read-only memories (ROMs), random access memories (RAMs) such as dynamic and static RAMs, erasable programmable read-only memories (EPROMs), electrically erasable programmable read-only memories (EEPROMs), flash memories, magnetic or optical cards, or any type of media suitable for storing electronic instructions.
Other embodiments may be implemented as software modules executed by a programmable control device. To that end, the methodology described herein for detection and control of a printer motor may be “offloaded”, at least in part, to a device external to the printer system 100. For example, the printer system 100 may be configured to communicate with a computer system (not shown) having a general-purpose processor and/or specific circuitry configured to perform one or more of the operations of the print engine 102 described herein.
Various features, aspects, and embodiments have been described herein. The features, aspects, and embodiments are susceptible to combination with one another as well as to variation and modification, as will be understood by those having skill in the art. The present disclosure should, therefore, be considered to encompass such combinations, variations, and modifications.
