US20110032583A1 - Apparatus and method for controlling the apparatus - Google Patents

Apparatus and method for controlling the apparatus Download PDF

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Publication number
US20110032583A1
US20110032583A1 US12/848,855 US84885510A US2011032583A1 US 20110032583 A1 US20110032583 A1 US 20110032583A1 US 84885510 A US84885510 A US 84885510A US 2011032583 A1 US2011032583 A1 US 2011032583A1
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United States
Prior art keywords
unit
value
speed
scanner unit
motor
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Abandoned
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US12/848,855
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English (en)
Inventor
Tomofumi Nishida
Nobutsune Kobayashi
Shinichi Yukiura
Hideyuki Kido
Ryoji Kanoyadani
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Canon Inc
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Canon Inc
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Assigned to CANON KABUSHIKI KAISHA reassignment CANON KABUSHIKI KAISHA ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: KANOYADANI, RYOJI, Kido, Hideyuki, KOBAYASHI, NOBUTSUNE, NISHIDA, TOMOFUMI, YUKIURA, SHINICHI
Publication of US20110032583A1 publication Critical patent/US20110032583A1/en
Priority to US14/056,224 priority Critical patent/US9232106B2/en
Abandoned legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/32—Circuits or arrangements for control or supervision between transmitter and receiver or between image input and image output device, e.g. between a still-image camera and its memory or between a still-image camera and a printer device
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/04—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa
    • H04N1/047—Detection, control or error compensation of scanning velocity or position
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/04—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa
    • H04N1/10—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa using flat picture-bearing surfaces
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/04—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa
    • H04N1/10—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa using flat picture-bearing surfaces
    • H04N1/1013—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa using flat picture-bearing surfaces with sub-scanning by translatory movement of at least a part of the main-scanning components
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/04—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa
    • H04N1/19—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa using multi-element arrays
    • H04N1/191—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa using multi-element arrays the array comprising a one-dimensional array, or a combination of one-dimensional arrays, or a substantially one-dimensional array, e.g. an array of staggered elements
    • H04N1/192—Simultaneously or substantially simultaneously scanning picture elements on one main scanning line
    • H04N1/193—Simultaneously or substantially simultaneously scanning picture elements on one main scanning line using electrically scanned linear arrays, e.g. linear CCD arrays
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N2201/00—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof
    • H04N2201/04—Scanning arrangements
    • H04N2201/047—Detection, control or error compensation of scanning velocity or position
    • H04N2201/04701—Detection of scanning velocity or position
    • H04N2201/04703—Detection of scanning velocity or position using the scanning elements as detectors, e.g. by performing a prescan

Definitions

  • the present invention relates to an apparatus configured to move a scanning unit to execute scanning and a method for controlling the apparatus.
  • the present invention relates to an apparatus that employs a direct current (DC) motor as a driving source and a method for controlling the apparatus.
  • DC direct current
  • a conventional image reading apparatus scans a document by using a scanner unit having a reading sensor while moving the scanner unit from an initial position of the scanner unit (a reference position) to read an image of the document.
  • An image reading apparatus like this generally uses a position detection sensor as a unit for determining an initial position of the scanner unit (i.e., a home position sensor).
  • a direction, in which a scanner unit is moved, is generally called a “main scanning direction” while a direction perpendicular to the main scanning direction is generally called a “sub scanning direction”.
  • a plurality of image reading sensors e.g., a charge-coupled device (CCD) sensor
  • Japanese Patent Application Laid-Open No. 08-22087 discusses a method that uses a plurality of home position sensors provided in the sub scanning direction.
  • the scanner unit can return to a home position that is currently the nearest of the home positions that the scanner unit has gone over.
  • Another conventional image reading apparatuses employ a DC motor as a driving source of the scanner unit.
  • Japanese Patent Application Laid-Open No. 10-42584 discusses an image input and output apparatus configured, if the speed of the driving motor of the scanner unit is abnormal, to immediately stop the motor. More specifically, the image input and output apparatus discussed in Japanese Patent Application Laid-Open No. 10-42584 estimates the current speed range based on the history of variation of the speed of the motor. If it is determined that the current speed of the motor has gone out of the estimated speed range, the method discussed in Japanese Patent Application Laid-Open No. 10-42584 determines that the motor is not normally controlled and compulsorily stops the motor.
  • the image reading apparatus described above does not have a sensor for detecting the position of the scanner unit, the image reading apparatus cannot use the sensor to determine the initial position of the scanner unit.
  • the conventional image reading apparatus described above initializes the position of the scanner unit by causing the scanner unit to contact the inner peripheral surface of the housing of the image input and output apparatus itself. After the position of the scanner unit is initialized in the above-described manner, the conventional image reading apparatus determines the initial (home) position by moving the scanner unit by a predetermined distance. The operation for initializing the position of the scanner unit is executed at the time of powering on the image reading apparatus, for example.
  • the scanner unit position initialization operation described above is executed by controlling the moving speed of the DC motor (the scanner unit driving source) to a low speed by limiting the value of the output current. Accordingly, it takes a long time to initialize the position of the scanner unit. In order to reduce the time taken for initializing the position of the scanner unit, it is necessary to increase the limit value of the output current to drive the scanner unit at a high speed.
  • the driving torque transmitted to the DC motor during the operation for contacting the scanner unit may become high due to differences in the configuration of the apparatuses. If the driving torque becomes high, the DC motor that drives the scanner unit may continue rotating after the scanner unit actually contacts the inner peripheral surface of the housing of the image reading apparatus. As a result, an encoder, which is mounted on a rotational axis of the DC motor, may also rotate. Accordingly, in this case, the state of the scanner unit contacting the inner peripheral surface of the housing of the image reading apparatus cannot be detected.
  • the image reading apparatus cannot correctly determine the initial position of the scanner unit.
  • the above-described problem may also arise in an apparatus other than the image reading apparatus configured to move the scanner unit.
  • an apparatus configured to move a unit to execute scanning by driving a motor
  • the apparatus includes an encoder configured to output a signal according to movement of the unit, an acquisition unit configured to acquire a value of current to be output to the motor, a speed control unit configured to execute control of a speed of the motor according to the signal output from the encoder and the value of the current acquired by the acquisition unit, a movement control unit configured to set a predetermined value as a threshold value, move the unit by driving the motor, by using the speed control unit, and a current control unit configured to set a value greater than the predetermined value according to the threshold value and the value of the current acquired by the acquisition unit at a predetermined timing during a time period in which the unit is being moved.
  • a method for controlling an apparatus including a motor, which is a source of driving a unit, and configured to move the unit, an encoder configured to output a signal according to movement of the unit, and a acquisition unit configured to acquire a value of current to be output to the motor, includes controlling a speed of driving the motor according to the signal output from the encoder and the value of the current acquired by the acquisition unit, moving the unit by driving the DC motor, by executing the speed control, and setting current to a value greater than the predetermined value according to the threshold value and the value of the current acquired by the acquisition unit at a predetermined timing during a time period in which the unit is being moved.
  • FIG. 1 illustrates an example of a mechanism of an image reading apparatus.
  • FIG. 2 is a plan view illustrating an example of the mechanism of the image reading apparatus viewed from a document stand.
  • FIG. 3 is a block diagram illustrating an exemplary configuration of the image reading apparatus.
  • FIG. 4 illustrates an example of scanner unit contact processing.
  • FIG. 5 is a graph illustrating exemplary variations in the speed of driving a scanner unit and a current applied to a motor when the scanner unit is driven according to a target speed, which has been set at the time of starting moving the scanner unit.
  • FIG. 6 is a graph illustrating an example of a relationship between the varied speed and the applied current when the speed of driving the scanner unit has not reached the target speed and the limit value of the current to be output has been reset.
  • FIG. 7 is a flow chart illustrating an example of processing for executing general feedback control on the speed.
  • FIG. 8 is a flow chart illustrating an example of processing for executing feedback control on the speed of moving the scanner unit, which additionally includes a calculation that enables execution of processing in which an output current is limited.
  • FIG. 9 is a flow chart illustrating an example of processing of a method that is characteristic to an exemplary embodiment of the present invention.
  • FIG. 10 illustrates an example of a mechanism of a recording apparatus.
  • FIG. 1 is a perspective view illustrating an example of an external appearance of the image reading apparatus.
  • an image reading apparatus 100 includes a housing 101 , which includes a control circuit, a document stand 102 , a scanner unit 103 , and a document cover 105 .
  • FIG. 2 is a top view of the image reading apparatus 100 illustrated in FIG. 1 .
  • the example illustrated in FIG. 2 illustrates an exemplary hardware configuration of the image reading apparatus 100 inside the housing 101 , which is viewed through a glass plate 201 of the document stand 102 over the document cover 105 , which is opened in the example illustrated in FIG. 2 .
  • a user opens the document cover 105 , places a document 104 on the glass plate 201 of the document stand 102 , and then causes the scanner unit 103 to scan the document 104 to read.
  • a home position 204 of the scanner unit 103 is set at a position to the left of the document stand 102 .
  • a contacting position 202 of the scanner unit 103 is set at a position opposite to the home position 204 of the scanner unit 103 .
  • the scanner unit 103 is moved in a direction indicated by an arrow 203 to reach the contact position 202 .
  • the scanner unit is moved in the main scanning direction, which is indicated by the arrow 203 in FIG. 2 .
  • the image reading apparatus 100 illustrated in FIGS. 1 and 2 which is connected to a host computer (not illustrated), reads an image according to an instruction from the host computer and outputs data of the read image to the host computer.
  • the image reading apparatus 100 is a flatbed type independent (integrated) apparatus.
  • the image reading apparatus 100 may be implemented by a scanner unit of a multifunction peripheral (MFP).
  • MFP multifunction peripheral
  • FIG. 3 is a block diagram illustrating an exemplary configuration of the image reading apparatus 100 related to control according to the present exemplary embodiment.
  • a central processing unit (CPU) 301 when a central processing unit (CPU) 301 receives an instruction from the host computer for starting reading an image of a document, the CPU 301 starts a document image reading operation.
  • a light source 306 which is included in the scanner unit 103 , is lit and a DC motor 303 , which is a driving source, starts rotating.
  • the scanner unit 103 is driven by the DC motor 303 to be moved to irradiate the document with light.
  • the reading sensor (CCD) 308 executes photoelectric conversion of the reflection light from the scanned document or light transmitted through the scanned document by using an analog front end (AFE) 309 .
  • An analog electric signal (image signal) generated by the photoelectric conversion is transmitted to the CPU 301 .
  • the image signal is subjected to analog-to-digital (A/D) conversion.
  • the A/D-converted signal is then subjected to image processing according to a program previously stored on a read-only memory (ROM) 311 .
  • the CPU 301 stores image data generated in the above-described manner on a random access memory (RAM) 310 .
  • the scanner unit 103 is moved in the following manner. More specifically, the CPU 301 calls and executes a control program from the ROM 311 and executes feedback control. Furthermore, the CPU 301 drives the DC motor 303 via a motor driver 302 .
  • a rotary encoder film 304 is read by using the encoder sensor 305 .
  • a signal acquired by reading the rotary encoder sensor 305 is output to the CPU 301 .
  • the CPU 301 receives the signal output from the DC motor 303 and acquires information about the speed of rotation of the DC motor 303 from the received signal.
  • the CPU 301 executes the feedback control for driving the scanner unit 103 according to the speed information acquired in the above-described manner.
  • FIG. 4 is a side cross section of the image reading apparatus 100 , which schematically illustrates an operation for determining an initial position (home position) of the scanner unit 103 . More specifically, FIG. 4 illustrates an example of scanner unit contact processing, which is executed to determine the initial position (home position) of the scanner unit 103 .
  • the scanner unit initial position determination processing includes the following two steps.
  • step S 1 the CPU 301 moves the scanner unit 103 towards the contact position 202 .
  • the scanner unit 103 contacts an inner wall surface of the housing 101 of the image reading apparatus 100 , which exists at the contact position 202 .
  • an operation for abutting the scanner unit 103 onto the inner wall surface of the housing 101 of the image reading apparatus 100 is referred to as “(to) contact” or “contact operation”.
  • Whether the scanner unit 103 has reached the contact position 202 i.e., whether the scanner unit 103 has contacted the inner wall surface of the housing 101 of the image reading apparatus 100 ) is determined according to the speed information acquired by using the encoder sensor 305 . If it is determined that the scanner unit 103 has reached the contact position 202 , the scanner unit 103 cannot be moved any further in this state. Accordingly, in this state, the CPU 301 acquires a value “0 [inch/sec]” as the speed information.
  • the CPU 301 suspends the driving of the scanner unit 103 and ends the scanner unit contact operation. Then the processing advances to step S 2 .
  • the present exemplary embodiment is not limited to this. More specifically, it is also useful if the CPU 301 determines that the scanner unit 103 has reached the target position if the value of the acquired speed information is equal to or less than a predetermined value.
  • step S 2 the CPU 301 executes control for moving the scanner unit 103 in a direction opposite to the direction of moving the scanner unit 103 in step S 1 at a predetermined speed.
  • a position distant from the contact position 202 by a predetermined distance is referred to as a “home position of the scanner unit 103 ”.
  • the CPU 301 determines the initial position (home position) of the scanner unit 103 .
  • FIG. 5 is a graph illustrating exemplary variations in the speed of driving the scanner unit 103 and a current supplied to the DC motor 303 when the scanner unit is driven and moved at a target speed spdTarget [inch(es)/sec], which has been set at the time of starting moving the scanner unit.
  • time is taken on its horizontal axis while the speed and the value of current are taken on the vertical axis, respectively.
  • the CPU 301 starts the scanner unit contact operation.
  • the CPU 301 calculates an average value of the values of the moving speed of the scanner unit 103 (“spdAvg” [inches/sec]), which are measured during the time period described above.
  • the CPU 301 calculates an average value of values of the supplied current (“mtrAvg” [A]), which are also measured during the above-described time period.
  • the CPU 301 determines that the scanner unit 103 has contacted the inner wall surface of the housing 101 of the image reading apparatus 100 .
  • a value of an average supplied current mtrAvg 504 indicates that the value of the output current has not reached an output current limit value (“mtrLimit”) 503 .
  • the scanner unit 103 is moved at the target speed spdTarget. Accordingly, it is understood that the output current limit value (“mtrLimit”) 503 , which has been set at the time of starting driving (moving) the scanner unit 103 , is an appropriate value uniquely and particularly to the image reading apparatus 100 .
  • the target speed spdTarget is set higher than the above-described value for the individual image reading apparatus 100 , then the driving torque generated by the DC motor 303 may become too high, although it is not in the example illustrated in FIG. 5 . Accordingly, it is understood that the target speed spdTarget illustrated in FIG. 5 is an appropriate value for the individual image reading apparatus 100 .
  • the average speed spdAvg 602 has a value lower than the value of a target speed spdTarget [inches/sec] 601 .
  • the current as high as the output current limit value mtrLimit has been applied (supplied) to the DC motor 303 to move the scanner unit 103 .
  • the average applied (supplied) current value (“mtrAvg”) 605 and an output current limit value (“mtrLimit”) 604 have the same value.
  • the individual image reading apparatus 100 is capable of increasing the speed of moving the scanner unit 103 up to the target speed spdTarget [inches/sec] 601 . Accordingly, it is useful if the output current limit value (“mtrLimit”) 604 is sufficiently higher than the value of the current to be supplied when the speed of moving the scanner unit 103 is raised up to spdTarget.
  • the CPU 301 multiplies the output current limit value (“mtrLimit”) 604 by a coefficient, which is calculated by an expression “spdTarget (target speed)/spdAvg (average scanner unit moving speed)”. Furthermore, the CPU 301 multiplies the result of the above-described multiplication by a conversion efficient “Param_UP”.
  • the conversion efficient “Param_UP” is used for increasing the difference (margin) of the output current limit value (“mtrLimit”) 604 from the value of the current to be supplied when the speed of moving the scanner unit 103 is raised up to spdTarget.
  • the CPU 301 updates the output current limit value (“mtrLimit”) 604 with the newly calculated value, which is calculated by executing the above-described multiplication operations.
  • the CPU 301 drives the scanner unit 103 according to the updated output current limit value (“mtrLimit”) 604 .
  • the speed of moving the scanner unit 103 When driving the scanner unit 103 is driven as described above, the speed of moving the scanner unit 103 , which is controlled according to the updated output current limit value (“mtrLimit”) 604 , reaches the target speed spdTarget 601 .
  • the example illustrated in FIG. 6 indicates a scanner unit moving speed 606 , which has been changed by updating the output current limit value.
  • FIG. 6 also indicates an example of an output current limit value 607 , which has been updated.
  • the example illustrated in FIG. 6 illustrates a supplied current 608 , which has been changed by updating the output current limit value.
  • FIG. 7 is a flow chart illustrating exemplary feedback control (servo control) of the scanner unit moving speed.
  • the control is executed for controlling the driving of the DC motor 303 , which is the driving source of driving the scanner unit 103 .
  • processing in steps S 701 through S 703 is processing that belongs to a layer of an image reading control task while processing in steps S 704 through S 713 is processing belonging to a layer of a timer handler, in terms of the software configuration of the present exemplary embodiment.
  • step S 701 the CPU 301 starts processing for driving the DC motor 303 , which is included in the control of the image reading operation.
  • step S 702 the CPU 301 initializes a variable intSum.
  • the variable “intSum” is a variable corresponding to the amount of integral compensation, which is calculated by integration executed during the feedback control.
  • step S 703 the CPU 301 activates a timer handler for executing the feedback control (the timer handler of the image reading apparatus 100 has a period of 1 msec). Then, the processing in the task layer ends. Thereafter, by executing timer processing in step S 704 , the CPU 301 executes each processing in step S 705 and subsequent steps every 1 msec.
  • step S 705 the CPU 301 determines whether the driving target unit (i.e., the scanner unit 103 in the present exemplary embodiment) has reached the target position. If it is determined that the scanner unit 103 has reached the target position (YES in step S 705 ), then the processing advances to step S 706 . In step S 706 , the CPU 301 stops the timer. In step S 707 , the CPU 301 discontinues (stops) the supply of current to the DC motor 303 . Then, the processing advances to step S 713 . In step S 713 , the CPU 301 ends the DC motor driving processing.
  • the present invention is not limited to this. More specifically, as another aspect of the present invention, it is also useful if the CPU 301 , in step S 707 , executes control for changing the value of the supplied current to a predetermined value so that the scanner unit 103 is not moved from the target position.
  • step S 708 the CPU 301 acquires information about the scanner unit moving speed (hereinafter referred to as “speed information”). More specifically, in step S 708 , the CPU 301 acquires current speed information from the encoder sensor 305 and substitutes the acquired current speed information into a variable spdNow.
  • step S 709 the CPU 301 executes a routine for generating an ideal speed profile. More specifically, in step S 709 , the CPU 301 acquires ideal speed information spdCmd, which is information about the ideal speed at the time of the current stage of the processing illustrated in FIG. 7 .
  • the ideal speed profile can be easily generated by integration of a speed command profile. That is, the ideal speed profile can be generated by a publicly known method. Accordingly, the detailed description thereof will not be made here.
  • Calculations in processing in steps S 710 and S 711 are examples of proportional-integral-derivative (PID) control.
  • PID control used in the present exemplary embodiment, feedback control is applied in controlling the speed of moving the scanner unit 103 .
  • the CPU 301 executes processing for executing integration in speed servo control. More specifically, in step S 710 , the CPU 301 calculates an amount of delay in the speed based on a difference between the speed command value spdCmd and the current speed information spdNow. Furthermore, the CPU 301 multiplies the calculated speed delay amount by an integral gain coefficient intTbl.
  • the CPU 301 adds the result of the multiplication by the integral gain coefficient intTbl to an integral compensation amount intSum, which has been calculated in the last interrupt by the timer having the period of 1 msec. In the above-described manner, the CPU 301 newly calculates the integral compensation amount intSum, which is the result of the integration.
  • step S 711 the CPU 301 executes a proportional operation in the speed servo control and then executes processing for determining the output current value. More specifically, in step S 711 , the CPU 301 calculates the difference between the speed command value spdCmd and the current speed information spdNow, and calculates the amount of delay of the speed based on the difference calculated in the above-described manner. Furthermore, the CPU 301 multiplies the calculated delay in the speed by an integral gain coefficient of the speed intTbl. Moreover, the CPU 301 adds the result of the integral operation intSum to the result of the proportional operation to acquire the output current value mtr_pwm.
  • step S 712 the CPU 301 executes control for supplying the current corresponding to the value of the mtr_pwm, which is the result of the above-described calculation, to the DC motor 303 . After that, the processing returns to step S 704 . In step S 704 , the CPU 301 executes processing of another task until a time period of 1 msec elapses.
  • FIG. 8 is a flow chart illustrating an example of processing for executing feedback control on the speed of moving the scanner unit 103 , which includes a calculation that enables execution of processing in which an output current is limited in addition to the feedback control for controlling the scanner unit moving speed described above with reference to FIG. 7 .
  • processing similar to that described above with reference to FIG. 7 is provided with the same step reference number as the corresponding processing illustrated in FIG. 7 . Accordingly, the description thereof will not be repeated here.
  • steps S 810 through S 816 which is uniquely included in the processing illustrated in FIG. 8 , only will be described in detail.
  • step S 810 the CPU 301 temporarily copies (stores) the result of the integral operation intSum into a backup variable area intOld.
  • the integral operation result intSum itself is to be overwritten in subsequent processing.
  • the CPU 301 backs up the integral operation result intSum in the backup variable area intOld as an old integral compensation amount.
  • Calculations in processing in steps S 811 and S 812 which is similar to the processing in steps S 710 and S 711 illustrated in FIG. 7 , are examples of the PID control, which is a publicly known control. In the PID control used in the present exemplary embodiment, feedback control is applied in controlling the position of the scanner unit 103 .
  • step S 813 Processing in step S 813 is remarkably different from the processing illustrated in FIG. 7 and that illustrated in FIG. 8 . More specifically, in step S 813 , the CPU 301 compares the output current value mtr_pwm with a predetermined threshold value mtrLimit. In step S 813 , the CPU 301 determines whether the output current value mtr_pwm is greater than the predetermined threshold value mtrLimit. If it is determined that the output current value mtr_pwm is equal to or smaller than the predetermined threshold value mtrLimit (NO in step S 813 ), then the processing advances to step S 816 . In step S 816 , the CPU 301 executes control for supplying the current corresponding to the value of the calculation result mtr_pwm to the DC motor 303 .
  • step S 813 the processing advances to step S 814 .
  • step S 814 the CPU 301 sets the threshold value mtrLimit as the output current value mtr_pwm.
  • a problem so-called “reset windup” may arise if the output of the calculation result exceeds a limit that has been set to the output in a system that is a control target. If an output has exceeded its limit value, feedback control is not effective. To paraphrase this, in this case, the feedback control fails and the output does not increase in proportion to the increase of the integral compensation amount. If the integral operation is continued in this state, the integral compensation amount is wound up.
  • the output does not decrease even if a deviation starts to decrease and the integral compensation amount is reduced. This is because the wound-up integral compensation amount is cancelled by reduction processing.
  • the feedback control becomes ineffective for a time period necessary for reducing the wound-up integral compensation amount. Accordingly, in this case, an overshoot of the result of the control may become too great.
  • the present exemplary embodiment uses a publicly known and widely used method in which if the output of the result of the calculation operation reaches its limit, the integral operation for further increasing the output of the calculation result is stopped. More specifically, in step S 815 , the CPU 301 stops the integral operation by substituting the integral compensation amount intSum with the backup variable intOld. After that, the processing advances to step S 816 . In step S 816 , the CPU 301 supplies the current corresponding to the value of the calculation result mtr_pwm to the DC motor 303 . Then, the processing returns to step S 704 . In step S 704 , the CPU 301 executes processing of another task until a time period of 1 msec elapses.
  • FIG. 9 is a flow chart illustrating an example of processing for causing the scanner unit 103 to contact the inner wall surface of the housing 101 of the individual image reading apparatus 100 .
  • the CPU 301 gives a command for starting the scanner unit contact operation.
  • the CPU 301 sets the target speed spdTarget [inches/sec] and the output current limit value mtrLimit [A], which have been previously set, to a built-in register, which is built in the CPU 301 .
  • step S 903 in order to cause the scanner unit 103 to contact the inner wall surface of the housing 101 as described above with reference to FIG. 4 , the CPU 301 starts moving the scanner unit 103 . More specifically, the CPU 301 executes control of driving by the DC motor 303 by using the target speed spdTarget and the output current limit value mtrLimit, which have been set in step S 902 , as parameters for the feedback control including the processing using the output current limit value mtrLimit described above with reference to the flow chart of FIG. 8 . The CPU 301 executes processing in step S 903 and subsequent steps according to the variation of the moving speed and the supplied current described above with reference to FIGS. 5 and 6 .
  • step S 905 the CPU 301 determines whether the scanner unit 103 has been moved according to the speed information acquired so far from the encoder sensor 305 . If it is determined that the scanner unit 103 has not been moved according to the speed information acquired so far from the encoder sensor 305 (NO in step S 905 ), then the processing advances to step S 910 . In step S 910 , the scanner unit contact operation ends.
  • step S 907 the CPU 301 determines whether the average speed spdAvg calculated in the above-described manner is the same as the target speed spdTarget that has been set in step S 902 .
  • step S 907 If it is determined that the average speed spdAvg has approximately the same value as the value of the target speed spdTarget (YES in step S 907 ), then the processing advances to step S 909 .
  • step S 909 the CPU 301 continues the control of the driving by the DC motor 303 at the output current limit value mtrLimit, which has been set when the scanner unit contact operation starting command is given, until the scanner unit contact operation is completed.
  • step S 908 the CPU 301 sets the output current limit value mtrLimit, which has a value greater than the value set in step S 902 .
  • the output current limit value mtrLimit set in step S 908 is calculated as described above with reference to FIG. 6 .
  • step S 909 the CPU 301 continues the control according to the updated output current limit value mtrLimit until the scanner unit contact operation is completed.
  • step S 909 If it is detected that the scanner unit 103 has contacted the inner wall surface of the housing 101 in step S 909 , then the processing advances to step S 910 .
  • step S 910 the CPU 301 ends the scanner unit contact operation.
  • the present exemplary embodiment calculates the average speed of moving the scanner unit 103 during the predetermined time period from the start of the scanner unit contact operation, and compares the calculated average moving speed with the predetermined target speed. Furthermore, the CPU 301 executes control for updating the limit value of the current to be output to the DC motor 303 . Furthermore, if it is determined that the speed of moving the scanner unit 103 has not reached the target speed, the CPU 301 supplies a current greater than the previously set value. Accordingly, the present exemplary embodiment can move the scanner unit 103 to the contact position at the increased speed.
  • the CPU 301 continues using the value set in step S 902 for the limit value of current to be output to the DC motor 303 . It is useful to set the value set in step S 902 according to the performance of an individual image reading apparatus 100 whose amount of excess of torque may become the highest, considering the difference in the mechanical configuration of the image reading apparatus 100 .
  • the present exemplary embodiment can prevent the torque from becoming too great due to excessive load on the DC motor 303 .
  • the present exemplary embodiment having the configuration described above can correctly detect the contacting state of the scanner unit 103 against the inner wall surface of the housing 101 .
  • the present exemplary embodiment can execute the optimum speed control according to the actual speed of moving the scanner unit 103 of each image reading apparatus. Accordingly, the present exemplary embodiment can execute the processing for initializing the position of the scanner unit 103 as quickly and accurately as possible.
  • the CPU 301 updates the output current limit value according to a result of comparison between the average speed of moving the scanner unit 103 and the target speed of moving the scanner unit 103 .
  • the present invention is not limited to this. More specifically, it is also useful if the CPU 301 updates (resets) the output current limit value to an optimum value according to a highest or lowest speed of moving the scanner unit 103 during a predetermined time period.
  • FIG. 10 illustrates an exemplary external configuration of a recording apparatus 1 .
  • the recording apparatus 1 includes a carriage 2 .
  • the carriage 2 includes an inkjet recording type recording head 3 , which execute recording by discharging ink.
  • the carriage 2 reciprocatingly moves in a direction indicated by an arrow A to execute recording.
  • the initial position of the carriage 2 (recording head 3 ) is determined according to the method described above.
  • the recording apparatus 1 feds a recording medium P, such as a recording paper, by using a paper feed mechanism 5 to a recording position. At the recording position, the recording head 3 discharges the ink on the recording medium P to execute recording.
  • a recording medium P such as a recording paper
  • the carriage 2 of the recording apparatus 1 includes an ink cartridge 6 in addition to the recording head 3 .
  • the ink cartridge 6 contains the ink to be supplied to the recording head 3 .
  • the ink cartridge 6 is detachably mounted in the carriage 2 .
  • the carriage 2 includes four ink cartridges, which contains a magenta (M) ink, a cyan (C) ink, a yellow (Y) ink, and a black (K) ink, respectively. Each of the four ink cartridges can be detached from the carriage 2 separately and independently from one another.
  • an inkjet type recording head which discharges the ink by utilizing thermal energy, is employed as the recording head 3 .
  • the present invention is not limited to this. More specifically, it is also useful if a piezoelectric type recording head is used as the recording head 3 .

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Facsimile Scanning Arrangements (AREA)
  • Optical Systems Of Projection Type Copiers (AREA)
US12/848,855 2009-08-05 2010-08-02 Apparatus and method for controlling the apparatus Abandoned US20110032583A1 (en)

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JP2009182890A JP5596946B2 (ja) 2009-08-05 2009-08-05 画像読取装置及び画像読取装置の制御方法

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CN101998022A (zh) 2011-03-30
CN101998022B (zh) 2013-12-04
JP2011035847A (ja) 2011-02-17
US20140036321A1 (en) 2014-02-06
US9232106B2 (en) 2016-01-05

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