US20030016965A1 - Image forming apparatus - Google Patents
Image forming apparatus Download PDFInfo
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- US20030016965A1 US20030016965A1 US09/905,908 US90590801A US2003016965A1 US 20030016965 A1 US20030016965 A1 US 20030016965A1 US 90590801 A US90590801 A US 90590801A US 2003016965 A1 US2003016965 A1 US 2003016965A1
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- United States
- Prior art keywords
- motor
- reference clock
- control circuit
- motor control
- image forming
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P5/00—Arrangements specially adapted for regulating or controlling the speed or torque of two or more electric motors
- H02P5/68—Arrangements specially adapted for regulating or controlling the speed or torque of two or more electric motors controlling two or more dc dynamo-electric motors
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/01—Apparatus for electrographic processes using a charge pattern for producing multicoloured copies
- G03G15/0142—Structure of complete machines
- G03G15/0178—Structure of complete machines using more than one reusable electrographic recording member, e.g. one for every monocolour image
- G03G15/0194—Structure of complete machines using more than one reusable electrographic recording member, e.g. one for every monocolour image primary transfer to the final recording medium
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G2215/00—Apparatus for electrophotographic processes
- G03G2215/01—Apparatus for electrophotographic processes for producing multicoloured copies
- G03G2215/0103—Plural electrographic recording members
- G03G2215/0119—Linear arrangement adjacent plural transfer points
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G2215/00—Apparatus for electrophotographic processes
- G03G2215/01—Apparatus for electrophotographic processes for producing multicoloured copies
- G03G2215/0103—Plural electrographic recording members
- G03G2215/0119—Linear arrangement adjacent plural transfer points
- G03G2215/0138—Linear arrangement adjacent plural transfer points primary transfer to a recording medium carried by a transport belt
- G03G2215/0141—Linear arrangement adjacent plural transfer points primary transfer to a recording medium carried by a transport belt the linear arrangement being horizontal
Definitions
- the present invention relates to an image forming apparatus such as a full-color copying machine, a color printer, or the like.
- a so-called train-of-four tandem full-color copying machine is known as an image forming apparatus which outputs a color image.
- this train-of-four tandem full-color copying machine four image forming units which respectively form toner images of colors of yellow (Y), magenta (M), cyan (C), and black (B) are provided in parallel along a conveyor belt, based on an image signal subjected to color separation.
- a DC motor is adopted as a drive system thereof.
- the train-of-four tandem full-color copying machine as an image forming apparatus generally adopts a “4-motor system” in which four photosensitive drums 100 Y, 100 M, 100 C, and 100 B are respectively driven by motors 101 Y, 101 M, 101 C, and 101 B.
- FIG. 1B it is possible to adopt a “1-motor system” in which four photosensitive drums 100 Y, 100 M, 100 C, and 100 B are all driven by one motor 102 .
- an electronic clutch or a mechanical 1-WAY clutch is adopted to switch a color mode in which the four photosensitive drums 100 Y, 100 M, 100 C, and 100 B are all driven and a black mode in which only the black photosensitive drum 100 B is driven.
- the 1-motor system provides a merit, compared with the 4-motor system.
- a “2-motor system” can be adopted, i.e., three photosensitive drums 100 Y, 100 M, and 100 C are driven by one motor 103 through a gear, a belt, or a roller and the remaining black photosensitive drum 100 B is driven by another motor 104 .
- the clutch part can be omitted, so that image jitters caused by mesh at the clutch part can be avoided.
- the load torque ratio is 3:1 under the condition that the drive gear ratio is constant.
- the load difference is thus large and causes a problem.
- the present invention has been made in view of the above problem and has an object of avoiding the problem of high costs when the 4-motor system is adopted and the problem of mesh at the clutch part when the 1-motor system is adopted, by adopting a 2-motor system.
- photosensitive drums for color components Y, M, and C are driven by one motor through a gear, belt, or roller, by adopting the 2-motor system.
- the photosensitive drum for the other remaining color component B is driven by another motor.
- a cost-reduction and preservation of image characteristics are both achieved by reducing the clutch part.
- an object is to prevent a difference from occurring in the peripheral speed at the rising/falling time between the motor for driving the photosensitive drum for the color component B and the motor for driving the photosensitive drums for the color components Y, M, and C, by controlling the drive current for driving the photosensitive drum for the color component B, to delay the rising time of the motor for driving the photosensitive drum for the color component B, even if two motors respectively having different numbers of FG pulses are used.
- an image forming apparatus comprises: a conveyor section which conveys an image forming medium; an image forming unit having a plurality of photosensitive drums for color components of yellow, magenta, cyan, and black arranged in parallel on the conveyor part and being rotatable, to transfer images of respective colors to the image forming medium being conveyed by the conveyor part; a first motor which drives all of the photosensitive drums for the color components of yellow, magenta, and cyan through a drive mechanism; a second motor which drives the photosensitive drum for the color component of black; a reference clock generation circuit which generates a reference clock for driving the motors; a first motor control circuit which drives and controls the first motor; a second motor control circuit for driving and controlling the second motor; and a reference clock multiplication/division circuit which multiplies/divides the reference clock, to output a result to the second motor control circuit.
- a method of forming an image according to the present invention is based on a two-motor system in which photosensitive drums for color components of yellow, magenta, and cyan are driven by a first motor and a photosensitive drum for a color component of black is driven by a second motor, and the method comprises: a first step of conveying an image forming medium; a second step of multiplying/dividing a reference clock to output a clock to a second motor control circuit for driving and controlling the second motor; and a third step of driving the first motor by a first motor controlling circuit based on the reference clock, to drive the photosensitive drums for the color components of yellow, magenta, and cyan, and of driving the second motor by the second motor control circuit based on the multiplied/divided clock, to drive the photosensitive drum for the color component of black, thereby to transfer images of respective colors to the image forming medium.
- FIG. 1A is a view which explains a 4-motor system adopted in a train-of-four tandem full-color copying machine as an image forming apparatus according to the prior art
- FIG. 1B is a view which explains a 1-motor system adopted in a train-of-four tandem full-color copying machine as an image forming apparatus according to the prior art
- FIG. 1C is a view which explains a 2-motor system adopted in a train-of-four tandem full-color copying machine as an image forming apparatus according to the prior art
- FIG. 2 is a diagram showing the structure of a color digital copying machine 1 as an example of an image forming apparatus according to an embodiment of the present invention
- FIG. 3 is a view showing the internal structure of the color digital copying machine 1 ;
- FIG. 4 is a diagram which explains a motor control part 30 for rotating and controlling photosensitive drums 21 Y, 21 M, 21 C, and 21 B;
- FIG. 5 is a view showing a state where a magnet encoder 36 Y ( 36 B) is provided around the rotor or rotation shaft of a DC motor 31 Y ( 31 B).
- FIG. 2 shows the structure of a color digital copying machine 1 as an example of an image forming apparatus according to the embodiment of the present invention, and explanation thereof will now be made below.
- the color digital copying machine 1 is constructed by a control part (CPU) 61 , a scanner 62 , an image forming unit 63 , and an operation panel 64 .
- This color digital copying machine 1 is connected with an external unit 66 such as a personal computer or the like through a communication channel 65 such as a LAN or the like.
- the control part 61 controls the entire color digital copying machine 1 .
- the scanner 62 reads image information from a copy target not shown, to generate an image signal.
- the image forming unit 63 forms an image corresponding to an image signal supplied from the scanner 62 or external unit 66 .
- the operation panel 64 is used by a user to make various settings.
- the control part 61 has an internal memory 61 a . Self-print image patterns for identifying a rotation angle change phase are previously registered in the internal memory 61 a.
- FIG. 3 shows the internal structure of the color digital copying machine 1 and explanation thereof will now be made below.
- the scanner 62 includes an illumination lamp 13 , a reflector 14 , reflection mirrors 15 to 17 , an imaging lens 18 , a light receiving element 19 , and an image processing device 20 .
- the illumination lamp 13 serves to illuminate an original document not shown but set on a document set table 12 .
- the reflector 14 serves to converge light from the illumination lamp 13 toward the original document.
- An optical system 29 serves to guide light reflected from the original document toward the light receiving element 19 , with use of the reflection mirrors 15 to 17 , the imaging lens 18 , and the like.
- the light receiving element 19 is a CCD or the like and serves to convert light from the original document into an electric signal.
- the image processing part 20 performs color separation on the photoelectrically converted electric signal, to obtain an image signal for respective colors of yellow (Y), magenta (M), cyan (C), and black (B).
- the image forming unit 63 has four image forming parts 4 Y, 4 M, 4 C, and 4 B, an exposure part 5 , a transfer belt 6 , and a fixing part 7 .
- the four image forming parts 4 Y, 4 M, 4 C, and 4 B form images of a total of four colors, i.e., Y, M, and C and B for compensation for brightness and darkness, which are respective color components of subtractive primaries.
- the exposure part 5 serves to irradiate exposure light (e.g., a laser beam) whose light intensity is intermittently changed in correspondence with an image signal supplied from the scanner unit 62 or the outside, on the photosensitive drums 21 Y, 21 M, 21 C, and 21 B provided at the image forming parts 4 Y, 4 M, 4 C, and 4 B.
- exposure light e.g., a laser beam
- the transfer belt 6 serves to overlap sequential images formed by the image forming parts 4 Y, 4 M, 4 C, and 4 B, on a paper P as a transfer material (image forming medium) while conveying the paper P.
- the fixing part 7 serves to press the paper P conveyed by the transfer belt 6 and an image (a developer image) on the paper P, while heating them, thereby to fix the developer image to the paper P.
- the image forming parts 4 Y, 4 M, 4 C, and 4 B have a substantially equal structure and form images corresponding to respective colors by a known electro-photographic process.
- the photosensitive drums 21 Y, 21 M, 21 C, and 21 B have an equal diameter.
- charger parts 22 Y, 22 M, 22 C, and 22 B developing parts 23 Y, 23 M, 23 C, and 23 B containing toners of corresponding colors, transfer parts 26 Y, 26 M, 26 C, and 26 B, cleaning parts 24 Y, 24 M, 24 C, and 24 B, and dischargers 25 Y, 25 M, 25 C, and 25 B are provided respectively.
- the transfer devices 26 Y, 26 M, 26 C, and 26 B are provided at positions opposite to and below the photosensitive drums 21 Y, 21 M, 21 C, and 21 B with the transfer belt 6 inserted.
- paper cassettes 8 a and 8 b are provided to maintain papers P to which toner images are transferred.
- the paper cassettes 8 a and 8 b are provided with pickup rollers 9 a and 9 b for picking up, one after another, papers P contained in the cassettes.
- a paper conveyor part 10 comprised of guides and rollers for feeding papers P picked up by the pickup rollers 9 a and 9 b toward the transfer belt 6 is formed between the transfer belt 6 and each of the cassettes 8 a and 8 b.
- an aligning roller 11 for setting a timing at which a paper P is fed toward the transfer belt 6 is provided to align the paper P, which has been picked up from any of the paper cassettes and is being conveyed in the paper conveyor part 10 , with positions of images to be formed by the image forming parts 4 Y, 4 M, 4 C, and 4 B.
- this color image forming apparatus 1 when an image signal is supplied from the scanner 62 or the external unit 66 , the photosensitive drums 21 Y, 21 M, 21 C, and 21 b of the image forming parts 4 Y, 4 M, 4 C, and 4 B are charged, in time sequence, to predetermined potentials by a charge power source device not shown. Further, a laser beam whose light intensity is intermittently changed on the bases of image signals is irradiated from the exposure part 5 onto the photosensitive drums 21 Y, 21 M, 21 C, and 21 B.
- electrostatic latent images corresponding to a color image to be outputted are formed on the photosensitive drums 21 Y, 21 M, 21 C, and 21 B of the four image forming parts 4 Y, 4 M, 4 C, and 4 B.
- the timings at which images are exposed on the photosensitive drums 21 Y, 21 M, 21 C, and 21 B of the image forming parts 4 Y, 4 M, 4 C, and 4 B are defined in a predetermined order in accordance with the movement of the paper P conveyed on the transfer belt 6 .
- the electrostatic latent images formed on the photosensitive drums 21 Y, 21 M, 21 C, and 21 B of the image forming parts 4 Y, 4 M, 4 C, and 4 B are arranged within the same image forming parts 4 Y, 4 M, 4 C, and 4 B.
- Toners are selectively supplied by the developing parts 23 Y, 23 M, 23 C, and 23 B containing toners (developing agents) of predetermined colors and are sequentially transferred to the paper P on the transfer belt 6 , by the transfer devices respectively opposed to the photosensitive drums 21 Y, 21 M, 21 C, and 21 B, with the transfer belt 6 interposed therebetween.
- every paper P is picked out from a cassette containing papers P of a size corresponding to a previously selected size or the size of an image exposed by the exposure part 5 . Further, each paper P is conveyed to the aligning roller 11 of the paper conveyor part 10 and is temporarily stopped by the aligning roller 11 .
- Each paper P is fed toward the transfer belt 6 from the aligning roller 11 at a timing of exposure of an image of the first color by the exposure part 5 or a predetermined timing.
- the paper P is electrified by a charger (for paper P) provided near the roller in the side of the paper feed part supporting the transfer belt 6 , and is brought into tight contact with the transfer belt 6 .
- the paper P on which toners or toner images have been formed by the image forming parts 4 Y, 4 M, 4 C, and 4 B is conveyed to the fixing part 7 .
- melted toners are fixed to the paper P.
- the motor control part 30 is constructed by a DC motor 31 Y for rotating the photosensitive drums 21 Y, 21 M, and 21 C, a DC motor 31 B for rotating the photosensitive drum 21 B, motor drivers 32 Y and 32 B for driving the DC motors 31 Y and 31 B, and a control circuit 33 .
- the embodiment of the present invention adopts the 2-motor system.
- the control circuit 33 is constructed by a control ASIC. More specifically, the control circuit 33 is constructed by an APC ON circuit 34 , motor control circuits 35 Y and 35 B, a reference clock multiplication/division circuit 52 .
- the photosensitive drums 21 Y, 21 M, 21 C, and 21 B are connected to the DC motors 31 Y for rotation and driving through a connection transmission part or the like not shown. These DC motors 31 Y and 31 B are respectively driven by separate motor control circuits 35 Y and 35 B.
- a magnet encoder 36 Y ( 36 B) as shown in FIG. 5 is provided around the rotor or rotation shaft of the DC motor 31 Y ( 31 B).
- An FG signal as an encoder pulse is outputted from an FG signal generation circuit 70 Y ( 70 B) including a magnetic resistance element (MR element) provided adjacent to the magnet encoder 36 Y ( 36 B).
- MR element magnetic resistance element
- S and N poles are alternately provided as shown in FIG. 5.
- the widths of S and N poles are different at a portion while the widths of S and N poles are equal at the other portions.
- the DC motor 31 Y and 31 B are rotated and controlled at an equal peripheral velocity by the motor control circuits 35 Y and 35 B, so that the photosensitive drums 21 Y, 21 M, 21 C, and 21 B are rotated at an equal velocity.
- Each of the motor control circuits 35 Y and 35 B is constructed by an adder/subtracter 41 , a speed control part (AFC) 42 , a phase control part (APC) 43 , and amplifiers (Gf) 44 , (Gp) 45 , and (G) 46 .
- the adder/subtracter adds clock signals from the control unit 61 or the reference clock multiplication/division circuit 52 , and subtracts a signal from the amplifier (Gf) 44 or (Gp) 45 .
- the speed control part (AFC) 42 outputs a signal based on an FG signal from the magnetic resistance element ( 37 Y and 37 B).
- the phase control part (APC) outputs a signal based on an FG signal from the magnetic resistance element ( 37 Y and 37 B).
- the amplifier (Gf) 44 amplifies a signal from the speed control part (AFC) 42 .
- the amplifier (Gp) 45 amplifies a signal from the phase control part (APC) 43 .
- the amplifier (G) 46 amplifies a signal from the adder/subtracter 41 .
- Each of the motor control circuits 35 Y and 35 B is supplied with a generated reference clock in a manner in which an angle target setting value is loaded to the register of the control part (CPU) 61 .
- FG signals as encoder pulses are supplied from the magnetic resistance elements 37 Y and 37 B. Further, the motor control circuits 35 Y and 35 B are supplied with an APC ON signal from an APC ON circuit 34 .
- the motor control circuits 35 Y and 35 B respectively output, to the motor drivers 32 Y and 32 B, signals for accelerating or decelerating the DC motors 31 Y and 31 B, with use of the speed control parts (AFC) 42 such that the frequency of the reference clock from the control part 61 or the reference clock multiplication/division circuit 52 matches with the frequency of the FG signal as an encoder pulse from each of the magnetic resistance elements 37 Y and 37 B.
- AFC speed control parts
- phase control parts (APC) 43 of the motor control circuits 35 Y and 35 B respectively perform control such that the reference clock frequency from the control part 61 is equal to the phase in one pulse of the frequency of the FG signal as an encoder pulse from each of the magnetic resistance elements 37 Y and 37 B when an APC ON signal is supplied from the APC ON circuit 34 .
- the APC ON circuit 34 is constructed by an AND circuit and outputs an APC ON signal to the phase control part (APC) 43 of each of the motor control circuits 35 Y and 35 B.
- the reference clock is rendered common to both motors and a reference clock multiplication/division circuit 52 is provided before the motor control part 35 B.
- FG (YMC): FG (B) reference clock (YMC) reference clock (B) is satisfied.
- 1 ⁇ 2 may be set as a count value in the reference clock multiplication/division circuit 52 before the black (B) motor control part 35 B.
- 4/5 may be set as a count value in the reference clock multiplication/division circuit 52 before the black (B) motor control part 35 B.
- the reference clock multiplication/division circuit 52 before the black (B) motor control part 35 B may be passed through.
- the synchronization drive control system adopts a method of adjusting the servo gain of the control circuit of the black photosensitive drum, thereby to delay the rise time of the black photosensitive drum.
- synchronization with FG cycles can be achieved if FG pulse frequencies outputted from motors are different from each other if two motors separately drive a group of Y, M, and C photosensitive drums and a B photosensitive drum.
- the load to the B photosensitive drum is about 1 ⁇ 3 of that to the Y, M, and C photosensitive drums or if the drive deceleration ratio of the B photosensitive drum is about 3 times that of the Y, M, and C photosensitive drums, the difference in rising/falling time can be reduced between motors.
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Color Electrophotography (AREA)
- Control Of Direct Current Motors (AREA)
- Control Of Multiple Motors (AREA)
- Discharging, Photosensitive Material Shape In Electrophotography (AREA)
- Electrophotography Configuration And Component (AREA)
- Control Or Security For Electrophotography (AREA)
Abstract
In the image forming apparatus and method of the present invention, the reference clock is rendered common and a reference multiplication/division circuit is provided before a motor control part, if two motors which output different numbers of FG pulses per rotation are used or if motors which output equal numbers of FG pulses per rotation are used at different deceleration ratios. As a result, synchronization with FG cycles can be achieved.
Description
- The present invention relates to an image forming apparatus such as a full-color copying machine, a color printer, or the like.
- A so-called train-of-four tandem full-color copying machine is known as an image forming apparatus which outputs a color image. In this train-of-four tandem full-color copying machine, four image forming units which respectively form toner images of colors of yellow (Y), magenta (M), cyan (C), and black (B) are provided in parallel along a conveyor belt, based on an image signal subjected to color separation. A DC motor is adopted as a drive system thereof.
- As shown in FIG. 1A, the train-of-four tandem full-color copying machine as an image forming apparatus according to the prior art generally adopts a “4-motor system” in which four
photosensitive drums motors - In contrast, as shown in FIG. 1B, it is possible to adopt a “1-motor system” in which four
photosensitive drums motor 102. - In case of adopting this 1-motor system, an electronic clutch or a mechanical 1-WAY clutch is adopted to switch a color mode in which the four
photosensitive drums photosensitive drum 100B is driven. The 1-motor system provides a merit, compared with the 4-motor system. - However, there is a problem that image jitters may occur depending on the precision of mesh at the clutch part. Therefore, gears with a highly precise mechanism are required in the case of adopting the 1-motor system.
- Meanwhile, as shown in FIG. 1C, a “2-motor system” can be adopted, i.e., three
photosensitive drums motor 103 through a gear, a belt, or a roller and the remaining blackphotosensitive drum 100B is driven by anothermotor 104. - If the 2-motor system is adopted, the clutch part can be omitted, so that image jitters caused by mesh at the clutch part can be avoided.
- In the 2-motor system, however, the load torque ratio is 3:1 under the condition that the drive gear ratio is constant. The load difference is thus large and causes a problem.
- If two motors of the same kind are adopted and if the drive gear ratio is changed to match the load torque ratio, the target peripheral velocities differ from each other so that the FG pulse frequencies generated per one rotation differ greatly. Therefore, it is difficult to achieve control with high precision for synchronizing rotations of the two
motors motors - The present invention has been made in view of the above problem and has an object of avoiding the problem of high costs when the 4-motor system is adopted and the problem of mesh at the clutch part when the 1-motor system is adopted, by adopting a 2-motor system.
- That is, photosensitive drums for color components Y, M, and C are driven by one motor through a gear, belt, or roller, by adopting the 2-motor system. The photosensitive drum for the other remaining color component B is driven by another motor. In this structure, a cost-reduction and preservation of image characteristics are both achieved by reducing the clutch part.
- Further, an object is to prevent a difference from occurring in the peripheral speed at the rising/falling time between the motor for driving the photosensitive drum for the color component B and the motor for driving the photosensitive drums for the color components Y, M, and C, by controlling the drive current for driving the photosensitive drum for the color component B, to delay the rising time of the motor for driving the photosensitive drum for the color component B, even if two motors respectively having different numbers of FG pulses are used.
- To achieve the above objects, an image forming apparatus according to the present invention comprises: a conveyor section which conveys an image forming medium; an image forming unit having a plurality of photosensitive drums for color components of yellow, magenta, cyan, and black arranged in parallel on the conveyor part and being rotatable, to transfer images of respective colors to the image forming medium being conveyed by the conveyor part; a first motor which drives all of the photosensitive drums for the color components of yellow, magenta, and cyan through a drive mechanism; a second motor which drives the photosensitive drum for the color component of black; a reference clock generation circuit which generates a reference clock for driving the motors; a first motor control circuit which drives and controls the first motor; a second motor control circuit for driving and controlling the second motor; and a reference clock multiplication/division circuit which multiplies/divides the reference clock, to output a result to the second motor control circuit.
- Further, a method of forming an image according to the present invention is based on a two-motor system in which photosensitive drums for color components of yellow, magenta, and cyan are driven by a first motor and a photosensitive drum for a color component of black is driven by a second motor, and the method comprises: a first step of conveying an image forming medium; a second step of multiplying/dividing a reference clock to output a clock to a second motor control circuit for driving and controlling the second motor; and a third step of driving the first motor by a first motor controlling circuit based on the reference clock, to drive the photosensitive drums for the color components of yellow, magenta, and cyan, and of driving the second motor by the second motor control circuit based on the multiplied/divided clock, to drive the photosensitive drum for the color component of black, thereby to transfer images of respective colors to the image forming medium.
- Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.
- The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description of the preferred embodiments given below, serve to explain the principles of the invention.
- FIG. 1A is a view which explains a 4-motor system adopted in a train-of-four tandem full-color copying machine as an image forming apparatus according to the prior art;
- FIG. 1B is a view which explains a 1-motor system adopted in a train-of-four tandem full-color copying machine as an image forming apparatus according to the prior art;
- FIG. 1C is a view which explains a 2-motor system adopted in a train-of-four tandem full-color copying machine as an image forming apparatus according to the prior art;
- FIG. 2 is a diagram showing the structure of a color
digital copying machine 1 as an example of an image forming apparatus according to an embodiment of the present invention; - FIG. 3 is a view showing the internal structure of the color
digital copying machine 1; - FIG. 4 is a diagram which explains a
motor control part 30 for rotating and controllingphotosensitive drums - FIG. 5 is a view showing a state where a
magnet encoder 36Y (36B) is provided around the rotor or rotation shaft of aDC motor 31Y (31B). - In the following, an embodiment of the present invention will be explained with reference to the drawings.
- FIG. 2 shows the structure of a color
digital copying machine 1 as an example of an image forming apparatus according to the embodiment of the present invention, and explanation thereof will now be made below. - As shown in FIG. 2, the color
digital copying machine 1 is constructed by a control part (CPU) 61, ascanner 62, animage forming unit 63, and anoperation panel 64. This colordigital copying machine 1 is connected with anexternal unit 66 such as a personal computer or the like through acommunication channel 65 such as a LAN or the like. - In this structure, the
control part 61 controls the entire colordigital copying machine 1. Thescanner 62 reads image information from a copy target not shown, to generate an image signal. Theimage forming unit 63 forms an image corresponding to an image signal supplied from thescanner 62 orexternal unit 66. Theoperation panel 64 is used by a user to make various settings. Thecontrol part 61 has aninternal memory 61 a. Self-print image patterns for identifying a rotation angle change phase are previously registered in theinternal memory 61 a. - FIG. 3 shows the internal structure of the color
digital copying machine 1 and explanation thereof will now be made below. - As shown in FIG. 3, the
scanner 62 includes anillumination lamp 13, areflector 14,reflection mirrors 15 to 17, animaging lens 18, alight receiving element 19, and animage processing device 20. Theillumination lamp 13 serves to illuminate an original document not shown but set on a document set table 12. Thereflector 14 serves to converge light from theillumination lamp 13 toward the original document. An optical system 29 serves to guide light reflected from the original document toward thelight receiving element 19, with use of thereflection mirrors 15 to 17, theimaging lens 18, and the like. Thelight receiving element 19 is a CCD or the like and serves to convert light from the original document into an electric signal. Theimage processing part 20 performs color separation on the photoelectrically converted electric signal, to obtain an image signal for respective colors of yellow (Y), magenta (M), cyan (C), and black (B). - The
image forming unit 63 has fourimage forming parts transfer belt 6, and afixing part 7. - The four
image forming parts scanner unit 62 or the outside, on thephotosensitive drums image forming parts transfer belt 6 serves to overlap sequential images formed by theimage forming parts part 7 serves to press the paper P conveyed by thetransfer belt 6 and an image (a developer image) on the paper P, while heating them, thereby to fix the developer image to the paper P. - The
image forming parts photosensitive drums - Further, in the peripheries of the
photosensitive drums charger parts parts transfer parts parts dischargers - By this structure, color images corresponding to
laser beams polygon mirror 5 a are formed. - The
transfer devices photosensitive drums transfer belt 6 inserted. - At predetermined positions below the
transfer belt 6,paper cassettes paper cassettes pickup rollers paper conveyor part 10 comprised of guides and rollers for feeding papers P picked up by thepickup rollers transfer belt 6 is formed between thetransfer belt 6 and each of thecassettes - Further, at a predetermined position of the
paper conveyor part 10 in the side of thetransfer belt 6, an aligningroller 11 for setting a timing at which a paper P is fed toward thetransfer belt 6 is provided to align the paper P, which has been picked up from any of the paper cassettes and is being conveyed in thepaper conveyor part 10, with positions of images to be formed by theimage forming parts - In this color
image forming apparatus 1, when an image signal is supplied from thescanner 62 or theexternal unit 66, thephotosensitive drums image forming parts photosensitive drums - In this manner, electrostatic latent images corresponding to a color image to be outputted are formed on the
photosensitive drums image forming parts photosensitive drums image forming parts transfer belt 6. - The electrostatic latent images formed on the
photosensitive drums image forming parts image forming parts parts transfer belt 6, by the transfer devices respectively opposed to thephotosensitive drums transfer belt 6 interposed therebetween. - Note that every paper P is picked out from a cassette containing papers P of a size corresponding to a previously selected size or the size of an image exposed by the exposure part5. Further, each paper P is conveyed to the aligning
roller 11 of thepaper conveyor part 10 and is temporarily stopped by the aligningroller 11. - Each paper P is fed toward the
transfer belt 6 from the aligningroller 11 at a timing of exposure of an image of the first color by the exposure part 5 or a predetermined timing. At this time, the paper P is electrified by a charger (for paper P) provided near the roller in the side of the paper feed part supporting thetransfer belt 6, and is brought into tight contact with thetransfer belt 6. The paper P on which toners or toner images have been formed by theimage forming parts part 7. At this fixingpart 7, melted toners are fixed to the paper P. - Next, a
motor control part 30 which rotates and controls thephotosensitive drums - As shown in FIG. 4, the
motor control part 30 is constructed by aDC motor 31Y for rotating thephotosensitive drums DC motor 31B for rotating thephotosensitive drum 21B,motor drivers DC motors control circuit 33. - Thus, the embodiment of the present invention adopts the 2-motor system.
- The
control circuit 33 is constructed by a control ASIC. More specifically, thecontrol circuit 33 is constructed by anAPC ON circuit 34,motor control circuits division circuit 52. Thephotosensitive drums DC motors 31Y for rotation and driving through a connection transmission part or the like not shown. TheseDC motors motor control circuits - A
magnet encoder 36Y (36B) as shown in FIG. 5 is provided around the rotor or rotation shaft of theDC motor 31Y (31B). - An FG signal as an encoder pulse is outputted from an FG
signal generation circuit 70Y (70B) including a magnetic resistance element (MR element) provided adjacent to themagnet encoder 36Y (36B). In themagnet encoder 36Y (36B), S and N poles are alternately provided as shown in FIG. 5. - Further, the widths of S and N poles are different at a portion while the widths of S and N poles are equal at the other portions. In this manner, the
DC motor motor control circuits photosensitive drums - Each of the
motor control circuits subtracter 41, a speed control part (AFC) 42, a phase control part (APC) 43, and amplifiers (Gf) 44, (Gp) 45, and (G) 46. - The adder/subtracter adds clock signals from the
control unit 61 or the reference clock multiplication/division circuit 52, and subtracts a signal from the amplifier (Gf) 44 or (Gp) 45. The speed control part (AFC) 42 outputs a signal based on an FG signal from the magnetic resistance element (37Y and 37B). - The phase control part (APC) outputs a signal based on an FG signal from the magnetic resistance element (37Y and 37B). The amplifier (Gf) 44 amplifies a signal from the speed control part (AFC) 42. The amplifier (Gp) 45 amplifies a signal from the phase control part (APC) 43. The amplifier (G) 46 amplifies a signal from the adder/
subtracter 41. - Each of the
motor control circuits - In addition, FG signals as encoder pulses are supplied from the
magnetic resistance elements motor control circuits APC ON circuit 34. - The
motor control circuits motor drivers DC motors control part 61 or the reference clock multiplication/division circuit 52 matches with the frequency of the FG signal as an encoder pulse from each of themagnetic resistance elements - The phase control parts (APC)43 of the
motor control circuits control part 61 is equal to the phase in one pulse of the frequency of the FG signal as an encoder pulse from each of themagnetic resistance elements APC ON circuit 34. - The APC ON
circuit 34 is constructed by an AND circuit and outputs an APC ON signal to the phase control part (APC) 43 of each of themotor control circuits - Thus, if the two
DC motors division circuit 52 is provided before themotor control part 35B. - In this manner, synchronization with the FG cycle can be achieved. This is a feature of the present invention.
- For example, if motors which output different numbers of FG pulses per rotation are used, the following is given.
- Suppose that FG (YMC)=100 pulses and FG (B)=50 pulses.
- FG (YMC): FG (B)=reference clock (YMC) reference clock (B) is satisfied.
- From this relationship, reference clock (B)=FG (B)/FG (YMC)*reference clock (YMC) is given.
- Therefore, ½ may be set as a count value in the reference clock multiplication/
division circuit 52 before the black (B)motor control part 35B. - As another example, the following is given if the deceleration ratios are different between the drive parts of YMC and B.
- Suppose that deceleration ratio (YMC)=10 and deceleration ratio (B)=8 are given.
- In this case, deceleration ratio (YMC): deceleration ratio (B)=reference clock (YMC): reference clock (B) is given.
- From this relationship, reference clock (B)=deceleration ratio (B)/deceleration ratio (YMC)*reference clock (YMC) is given.
- Therefore, 4/5 may be set as a count value in the reference clock multiplication/
division circuit 52 before the black (B)motor control part 35B. - Further, in another example in which the motors for YMC and B use equal numbers of FG pulses per rotation and also equal deceleration ratios, the reference clock multiplication/
division circuit 52 before the black (B)motor control part 35B may be passed through. - As a further example, in order to reduce the difference between the rise time of the motors of the Y, M, and C photosensitive drums having heavy loads and the rise time of the motor of the black photosensitive drum having a light load, the synchronization drive control system adopts a method of adjusting the servo gain of the control circuit of the black photosensitive drum, thereby to delay the rise time of the black photosensitive drum.
- As has been explained above, according to the present invention, synchronization with FG cycles can be achieved if FG pulse frequencies outputted from motors are different from each other if two motors separately drive a group of Y, M, and C photosensitive drums and a B photosensitive drum.
- Further, if the load to the B photosensitive drum is about ⅓ of that to the Y, M, and C photosensitive drums or if the drive deceleration ratio of the B photosensitive drum is about 3 times that of the Y, M, and C photosensitive drums, the difference in rising/falling time can be reduced between motors.
- Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.
Claims (8)
1. An image forming apparatus comprising:
a conveyor unit which conveys an image forming medium;
an image forming unit having a plurality of photosensitive drums for color components of yellow, magenta, cyan, and black arranged in parallel on the conveyor part and being rotatable, to transfer images of respective colors to the image forming medium being conveyed by the conveyor part;
a first motor which drives all of the photosensitive drums for the color components of yellow, magenta, and cyan through a drive mechanism;
a second motor which drives the photosensitive drum for the color component of black;
a reference clock generation circuit which generates a reference clock for driving the motors;
a first motor control circuit which drives and controls the first motor;
a second motor control circuit which drives and controls the second motor; and
a reference clock multiplication/division circuit which multiplies/divides the reference clock, to output a result to the second motor control circuit.
2. The apparatus according to claim 1 , wherein
if the first and second motors which output different numbers of FG pulses in accordance with rotation of the photosensitive drums are used, the reference clock multiplication/division circuit multiplies/divides a reference clock by a ratio of the numbers of the FG pulses and outputs a result to the second motor control circuit.
3. The apparatus according to claim 1 , wherein
if the first and second motors which output different numbers of FG pulses in accordance with rotation of the photosensitive drums are used, the reference clock multiplication/division circuit multiplies/divides a reference clock by a ratio of deceleration ratios of drive mechanisms and outputs a result to the second motor control circuit.
4. The apparatus according to claim 1 , wherein
the reference clock multiplication/division circuit adjusts a servo gain of a motor control circuit of the photosensitive drum for the color component of black, to delay a rising time of the photosensitive drum for the color component of black.
5. A method of forming an image, based on a two-motor system in which photosensitive drums for color components of yellow, magenta, and cyan are driven by a first motor and a photosensitive drum for a color component of black is driven by a second motor, the method comprising:
a first step of conveying an image forming medium;
a second step of multiplying/dividing a reference clock to output a clock to a second motor control circuit for driving and controlling the second motor; and
a third step of driving the first motor by a first motor controlling circuit based on the reference clock, to drive the photosensitive drums for the color components of yellow, magenta, and cyan, and of driving the second motor by the second motor control circuit based on the multiplied/divided clock, to drive the photosensitive drum for the color component of black, thereby to transfer images of respective colors to the image forming medium.
6. The method according to claim 5 , wherein
in the second step, if the first and second motors which output different numbers of FG pulses in accordance with rotation of the photosensitive drums are used, a reference clock is multiplied/divided by a ratio of the numbers of the FG pulses and a result is outputted to the second motor control circuit.
7. The method according to claim 5 , wherein
in the second step, if the first and second motors which output different numbers of FG pulses in accordance with rotation of the photosensitive drums are used, a reference clock is multiplied/divided by a ratio of deceleration ratios of drive mechanisms and a result is outputted to the second motor control circuit.
8. The method according to claim 5 , wherein
a servo gain of the second motor control circuit of the photosensitive drum for the color component of black is adjusted to delay a rising time of the photosensitive drum for the color component of black.
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
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US09/905,908 US6519432B1 (en) | 2001-07-17 | 2001-07-17 | Image forming apparatus |
JP2001285705A JP4727098B2 (en) | 2001-07-17 | 2001-09-19 | Image forming apparatus and image forming method |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/905,908 US6519432B1 (en) | 2001-07-17 | 2001-07-17 | Image forming apparatus |
Publications (2)
Publication Number | Publication Date |
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US20030016965A1 true US20030016965A1 (en) | 2003-01-23 |
US6519432B1 US6519432B1 (en) | 2003-02-11 |
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ID=25421675
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US09/905,908 Expired - Lifetime US6519432B1 (en) | 2001-07-17 | 2001-07-17 | Image forming apparatus |
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US (1) | US6519432B1 (en) |
JP (1) | JP4727098B2 (en) |
Cited By (8)
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US20020149329A1 (en) * | 2001-02-06 | 2002-10-17 | Konica Corporation | Image forming apparatus and control method of motor therein |
US20050163534A1 (en) * | 2004-01-28 | 2005-07-28 | Samsung Electronics Co., Ltd. | Image forming apparatus and a driving method for the same |
EP1585311A3 (en) * | 2004-04-08 | 2008-03-05 | Ricoh Company, Ltd. | Method of preventing an image displacement |
US20080085130A1 (en) * | 2006-10-04 | 2008-04-10 | Ricoh Company, Limited | Image forming apparatus |
US20080286011A1 (en) * | 2007-05-15 | 2008-11-20 | Canon Kabushiki Kaisha | Color electrophotographic image forming apparatus |
US20090317148A1 (en) * | 2008-06-20 | 2009-12-24 | Canon Kabushiki Kaisha | Image forming apparatus and method for controlling same |
US8219004B2 (en) * | 2008-06-13 | 2012-07-10 | Sharp Kabushiki Kaisha | Image forming apparatus |
US9024568B2 (en) | 2011-06-02 | 2015-05-05 | Ricoh Company, Ltd. | Motor speed controller and control method |
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JP2004117644A (en) * | 2002-09-25 | 2004-04-15 | Canon Inc | Electrophotographic image forming apparatus |
JP4919679B2 (en) * | 2006-03-15 | 2012-04-18 | 株式会社リコー | Rotating body driving device, process cartridge, and image forming apparatus |
JP2010186155A (en) * | 2008-07-31 | 2010-08-26 | Brother Ind Ltd | Image forming apparatus |
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JPS63221362A (en) * | 1987-03-11 | 1988-09-14 | Canon Inc | Recorder |
JPH02157868A (en) | 1988-12-12 | 1990-06-18 | Fujitsu Ltd | Color recorder |
US5386286A (en) * | 1992-09-24 | 1995-01-31 | Kabushiki Kaisha Toshiba | Image forming apparatus |
JP3244098B2 (en) * | 1994-07-29 | 2002-01-07 | 松下電器産業株式会社 | Motor speed control device |
JPH0950165A (en) | 1995-08-07 | 1997-02-18 | Canon Inc | Multi-color recorder and method for driving and controlling the same |
JP3455067B2 (en) | 1997-07-01 | 2003-10-06 | シャープ株式会社 | Color image forming equipment |
JP2001069775A (en) * | 1999-08-30 | 2001-03-16 | Toshiba Tec Corp | Imaging apparatus and motor controller |
-
2001
- 2001-07-17 US US09/905,908 patent/US6519432B1/en not_active Expired - Lifetime
- 2001-09-19 JP JP2001285705A patent/JP4727098B2/en not_active Expired - Fee Related
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US6724161B2 (en) * | 2001-02-06 | 2004-04-20 | Konica Corporation | Image forming apparatus and control method of motor therein |
US20020149329A1 (en) * | 2001-02-06 | 2002-10-17 | Konica Corporation | Image forming apparatus and control method of motor therein |
US20050163534A1 (en) * | 2004-01-28 | 2005-07-28 | Samsung Electronics Co., Ltd. | Image forming apparatus and a driving method for the same |
US7356285B2 (en) * | 2004-01-28 | 2008-04-08 | Samsung Electronics Co., Ltd. | Image forming apparatus and a driving method for the same having concurrently stopping motors |
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US7751755B2 (en) * | 2006-10-04 | 2010-07-06 | Ricoh Company, Limited | Image forming apparatus |
US20080085130A1 (en) * | 2006-10-04 | 2008-04-10 | Ricoh Company, Limited | Image forming apparatus |
US20080286011A1 (en) * | 2007-05-15 | 2008-11-20 | Canon Kabushiki Kaisha | Color electrophotographic image forming apparatus |
US20110076060A1 (en) * | 2007-05-15 | 2011-03-31 | Canon Kabushiki Kaisha | Color electrophotographic image forming apparatus |
US7933538B2 (en) * | 2007-05-15 | 2011-04-26 | Canon Kabushiki Kaisha | Color electrophotographic image forming apparatus including a rotary drive transmission mechanism |
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US8219004B2 (en) * | 2008-06-13 | 2012-07-10 | Sharp Kabushiki Kaisha | Image forming apparatus |
US20090317148A1 (en) * | 2008-06-20 | 2009-12-24 | Canon Kabushiki Kaisha | Image forming apparatus and method for controlling same |
US8442419B2 (en) * | 2008-06-20 | 2013-05-14 | Canon Kabushiki Kaisha | Image forming apparatus and method for controlling same |
US9024568B2 (en) | 2011-06-02 | 2015-05-05 | Ricoh Company, Ltd. | Motor speed controller and control method |
Also Published As
Publication number | Publication date |
---|---|
US6519432B1 (en) | 2003-02-11 |
JP4727098B2 (en) | 2011-07-20 |
JP2003029492A (en) | 2003-01-29 |
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