JP2009169000A - Dc motor controller, developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a DC motor controller capable of controlling rotational speed of a DC motor to predetermined rotational speed in a short period of time. <P>SOLUTION: The DC motor controller makes the DC motor to rotate at the predetermined rotational speed by supplying voltage to the DC motor, supplies voltage higher than voltage corresponding to target speed to the DC motor (S12), monitors counter electromotive voltage generated by rotation of the DC motor (S13), and controls voltage to be supplied so as not to exceed the target speed according to the monitored counter electromotive voltage (S14, S15). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a DC motor control device, a developing device, and an image forming apparatus, and in particular, a DC motor control device capable of controlling the rotational speed of a DC motor, a developing device including such a DC motor control device, and an image forming apparatus. It relates to the device.

  The developing device included in the image forming apparatus forms an electrostatic latent image on the photoreceptor based on the read image data, and supplies a developer such as toner to obtain a visible image, which is then transferred to a sheet. Output. Since toner is consumed every time an image is formed, it is necessary to supply new toner to the developing device. The toner stored in the toner hopper or the like is supplied into the developing device by rotating a rotating body such as a toner supply motor or a toner supply roller rotated by the motor. In this case, it is required to stably supply the toner according to the amount of toner consumption.

Japanese Patent Laid-Open No. 2001-166578 (Patent Document 1) discloses an image forming apparatus in which a driving time and a toner replenishment amount are constant when a toner replenishing motor is rotated to replenish toner. Yes. According to Japanese Patent Application Laid-Open No. 2004-260260, a table is provided in which the driving time and the toner replenishment amount are constant, and the driving time of the toner replenishing motor is determined from the accumulated rotational speed using this table.
JP 2001-166578 A

  In order to stably supply toner by the rotation of the motor, it is necessary to set the rotation speed of the motor to a predetermined rotation speed (hereinafter referred to as “target speed”) in a short time. Here, it is conceivable to use a stepping motor or a DC brushless motor in order to achieve the target rotational speed in a short time. However, these motors are expensive and problematic in terms of cost.

  On the other hand, when an inexpensive DC brush motor (hereinafter simply referred to as “DC motor”) that rotates according to the supplied voltage is used, there are the following problems. 6 and 7 are diagrams showing the relationship between the setting of the voltage supplied to the conventional DC motor and the rotational speed of the DC motor. 6 and 7, the upper thick line indicates the setting of the voltage supplied to the DC motor, and the lower thin line indicates the rotational speed of the DC motor. In FIG. 6 and FIG. 7, the dotted line indicates the target speed of the DC motor. In addition, the horizontal direction on the paper represents the time axis, and in FIGS. 6 and 7, the time advances from left to right.

Referring to FIG. 6, when the voltage of the DC motor is set to voltage V ₁ corresponding to the target speed, it takes a long time indicated by time T ₁ to reach the target speed from the speed 0 state. become. In addition, referring to FIG. 7, when a voltage V ₂ higher than the voltage V ₁ corresponding to the target speed is supplied in advance at the initial stage of driving and the target speed is reached in a short time, the rotational speed of the DC motor is increased. will be greatly overshoots the target speed, so that by the time resulting in a target speed takes a long time indicated by the time T _2. In particular, when the variation in the quality of the DC motor is taken into account, this overshoot may be further increased. Incidentally, the time _{T 1} and time _{T 2} are, in particular, is about 200-300 ms.

  An object of the present invention is to provide a DC motor control device capable of setting the rotational speed of a DC motor to a predetermined rotational speed in a short time.

  Another object of the present invention is to provide a developing device capable of improving image quality.

  Still another object of the present invention is to provide an image forming apparatus capable of further improving image quality.

  The DC motor control device according to the present invention is a DC motor control device that rotates a DC motor at a predetermined rotational speed by supplying a voltage to the DC motor, and the DC motor is controlled by a voltage corresponding to the predetermined rotational speed. The voltage supply means for supplying a higher voltage, the monitoring means for monitoring the counter electromotive voltage generated by the rotation of the DC motor, and the rotational speed of the DC motor according to the counter electromotive voltage monitored by the monitoring means Control means for controlling the voltage supplied by the voltage supply means so as not to exceed the speed.

  Preferably, the control means operates when the DC motor is started.

  The control means may control the voltage supply means so that the voltage is lower than the high voltage when the rotation speed of the DC motor exceeds a predetermined rotation speed. Further, the control means may control the voltage supply means so as to maintain a high voltage when the rotational speed of the DC motor does not exceed a predetermined rotational speed.

  More preferably, the control means includes calculation means for calculating the rotational speed of the DC motor from the back electromotive voltage.

  In another aspect of the present invention, the developing device includes a DC motor and a rotating body that is rotated by the DC motor, and supplies the toner into the developing device that stores the developer by the rotation of the rotating body. Here, the developing device includes any of the motor control devices described above.

  In still another aspect of the present invention, an image forming apparatus includes the developing device described above.

  According to the present invention, a voltage higher than a voltage corresponding to a predetermined rotation speed is supplied to the DC motor, the counter electromotive voltage generated by the rotation of the DC motor is monitored, and the supplied voltage is controlled according to the counter electromotive voltage. To do. If it does so, a voltage higher than the voltage corresponding to a predetermined rotational speed can be supplied, and a DC motor can be made to reach a predetermined rotational speed in a short time. In this case, the back electromotive voltage generated by the rotation of the DC motor is monitored, and the supplied voltage is controlled in accordance with the back electromotive voltage, so that overshoot can be eliminated. Therefore, the rotational speed of the DC motor can be set to a predetermined speed in a short time.

  In addition, since such a developing device includes a DC motor control device capable of setting the rotational speed of the DC motor to a target speed in a short time, the toner can be supplied more stably into the developing device, Can improve the quality.

  In addition, since such an image forming apparatus includes a developing device that can improve image quality, the image quality can be improved.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of a digital multifunction peripheral 10 when an image forming apparatus including a developing device including a DC motor control device according to an embodiment of the present invention is applied to the digital multifunction peripheral 10. Referring to FIG. 1, a digital multifunction peripheral 10 displays a control unit 11 that controls the entire digital multifunction peripheral 10, a DRAM 12 for writing and reading image data and the like, and information that the digital multifunction peripheral 10 has. An operation unit 13 that includes a display screen and serves as an interface with the user in the digital multi-function peripheral 10, a document feeder 14 that automatically transports a document to a predetermined document reading position, and a document that has been transported by the document feeder 14 An image reading unit 15 that reads the image at a predetermined reading position, a developing device 16 that forms the image from a document read by the image reading unit 15 and outputs the image to a sheet, and a hard disk 17 that stores image data and the like A FAX communication unit 18 connected to the public line 20 and a network IF (interface) for connecting to the network 21 And a part 19.

  The control unit 11 compresses and writes the original data supplied from the image reading unit 15 in the DRAM 12, reads the data written in the DRAM 12, decompresses and encodes it, and outputs it by the developing device 16.

  The digital multifunction peripheral 10 operates as a copying machine by forming an image in the developing device 16 via the DRAM 12 using the document read by the image reading unit 15. The digital multifunction machine 10 operates as a printer by forming an image in the developing device 16 via the DRAM 12 using image data transmitted from the personal computer 22 connected to the network 21 through the network IF unit 19. To do. Further, the digital multi-function peripheral 10 forms an image in the developing device 16 via the DRAM 12 using the image data transmitted from the public line 20 through the FAX communication unit 18, and also reads by the image reading unit 15. By transmitting the image data of the original document to the public line 20 through the FAX communication unit 18, the facsimile apparatus operates.

  In FIG. 1, thick arrows indicate the flow of image data, and thin arrows indicate the flow of control signals or control data.

  Next, the configuration of the developing device 16 will be described. FIG. 2 is a schematic view showing a part of the developing device 16 provided in the digital multifunction peripheral 10. In FIG. 2, the flow of paper is indicated by arrows. Referring to FIGS. 1 and 2, the developing device 16 can form full-color images, and develops 26a, 26b, 26c, and 26d corresponding to four colors of yellow, cyan, magenta, and black, and each developing unit. And a transfer belt 27 as an intermediate transfer member for transferring the image of each color developed in the devices 26a to 26d.

  The developing device 26a includes a photosensitive member 25a, a developing sleeve 31a that supplies toner (not shown) as a developer to the photosensitive member 25a, and a toner that replenishes toner into the developing device 26a from a toner hopper 33a that stores the toner. A replenishing roller 32a and a DC motor controller (not shown) for controlling the rotation speed of the toner replenishing roller 32a rotated by a DC motor (not shown) are included. A developing sleeve 31a is provided at a position closest to the photoreceptor 25a, a toner supply roller 32a is provided above the developing sleeve 31a, and a toner hopper 33a is provided above the developing sleeve 31a. The toner replenishing roller 32a as a rotating body is rotated by a DC motor, and the toner in the toner hopper 33a is replenished to the developer 26a by the rotation of the toner replenishing roller 32a. The amount of toner supply corresponds to the rotational speed of the toner supply roller 32a. The toner replenished in the developing unit 26a is stirred and charged together with a carrier (not shown) in the developing unit 26a, and then supplied from the developing sleeve 31a to the photosensitive member 25a for development. In this way, an image is formed by the developing device 26a. Control of the rotation speed of the toner supply roller 32a will be described later.

  As for the other developing devices 26b to 26d, the developing sleeves 31b, 31c, and 31d that supply toner to the photosensitive members 25b, 25c, and 25d and the toner hoppers 33b, 33c, and 33d that store the toner to the developing devices 26b and 26c. 26d, toner supply rollers 32b, 32c and 32d for supplying toner. Since the configuration of the developing units 26b to 26d is the same as that of the developing unit 26a, the description thereof is omitted.

  The images of the respective colors formed by the developing units 26 a to 26 d are transferred so as to be sequentially superimposed on the transfer belt 27. In this way, a full color image is formed on the transfer belt 27 by superimposing the four color images. That is, the developing sleeves 31a to 31d and the magnet rollers 32a to 32d are used to form a full color image. The full color image formed on the transfer belt 27 is transferred to the paper P fed from the cassette 24 to the transfer unit 28. The paper P to which the full color image has been transferred is discharged to the discharge tray 29 through a fixing unit (not shown).

  Here, the configuration of the DC motor control device that controls the rotational speed of the DC motor that rotates the toner supply roller 32a will be described. FIG. 3 is a block diagram illustrating a configuration of the DC motor control device 41. 1 to 3, the DC motor control device 41 includes a DC motor 42 that rotates the toner supply roller 32 a, a DC motor control unit 43 that controls the operation of the DC motor 42, and a DC motor control unit 43. A comparator 44 that transmits a control signal to the DC motor 42 and a PWM (Pulse Width Modulation) 45 are provided. The DC motor control unit 43 is controlled by the control unit 11 provided in the digital multifunction peripheral 10.

  The DC motor control unit 43 includes an A / D converter and a D / A converter, and supplies a voltage to the DC motor 42 by a reference wave or the like. The DC motor 42 rotates at a rotation speed corresponding to the supplied voltage. That is, if a high voltage is supplied, it rotates at a high rotation speed, and if a low voltage is supplied, it rotates at a low rotation speed. The DC motor control unit 43 can vary the voltage supplied to the DC motor 42 by using an asynchronous rectifier circuit including the PWM 45 and the like. Specifically, the voltage ratio supplied to the DC motor 42 is controlled by controlling the duty ratio of the PWM 45.

  Here, in the DC motor control device 41, the counter electromotive voltage generated by the rotation of the DC motor 42 is fed back from the PWM 45 to the DC motor control unit 43. The DC motor control unit 43 calculates the rotational speed of the DC motor 42 from the fed back counter electromotive voltage. Here, the DC motor control unit 43 operates as calculation means. The DC motor control unit 43 controls the supplied voltage based on the calculated rotation speed of the DC motor 42. That is, the counter electromotive voltage fed back is monitored to control the voltage supplied to the DC motor 42. Here, the DC motor control unit 43 operates as monitoring means and control means.

  Next, the operation when the DC motor control device 41 rotates the DC motor 42 at the target speed will be described. FIG. 4 is a flowchart showing the operation of the DC motor control unit 43 in this case. FIG. 5 is a diagram showing the relationship between the setting of the voltage supplied to the DC motor 42 and the rotational speed of the DC motor 42, and corresponds to FIG. 6 and FIG. Here, it is assumed that the DC motor 42 is rotated at the target speed when the DC motor 42 is started, that is, from the state where the DC motor 42 is not rotating.

Referring to FIGS. 1 to 5, when DC motor 42 is activated, a request for rotation of DC motor 42 is received so as to rotate toner supply roller 32 a at a target speed (step S <b> 11 in FIG. 4, and the following steps are omitted). To do). Then, the DC motor control unit 43 supplies a voltage V ₂ higher than the voltage V ₁ corresponding to the target speed (S12). This is because the supplied voltage is increased so that the rotational speed of the DC motor 42 reaches the target speed in a short time. Here, the DC motor control unit 43 operates as voltage supply means. Thereafter, the counter electromotive voltage generated by the rotation of the DC motor 42 is monitored by the above-described method (S13). Specifically, the rotational speed of the DC motor 42 calculated based on the counter electromotive voltage is monitored. This monitoring is repeated every several milliseconds, for example, every 1 millisecond.

Next, it is determined whether or not the DC motor 42 does not exceed the target speed, that is, whether or not the target speed has been reached (S14). If the target speed has not been reached (NO in S14), the supplied voltage is controlled (S15), and the voltage is supplied. Specifically, when the rotational speed of the DC motor 42 exceeds the target speed, control is performed so that the high voltage is lowered. On the other hand, when the target speed is not exceeded, control is performed so as to maintain a high voltage. If the rotational speed of DC motor 42 has reached the target speed after elapse of time t (YES in S14), DC motor 42 is rotated at the target speed as it is (S16). The time t is the order of a few tens of milliseconds, which is much shorter than the time T ₁ and time T ₂ shown in FIGS. 6 and 7 as described above.

Thus, according to the DC motor controller 41, a high voltage V ₂ than the voltages V ₁ corresponding to the target speed is supplied to the DC motor 42, monitors the counter electromotive voltage generated by the rotation of the DC motor 42, the reverse The supplied voltage is controlled according to the electromotive voltage. Then, the voltage V ₂ higher than the voltage V ₁ corresponding to the target speed can be supplied, and the DC motor 42 can reach the target speed in a short time. In this case, the counter electromotive voltage generated by the rotation of the DC motor 42, specifically, the rotational speed of the DC motor 42 calculated from the counter electromotive voltage is monitored, and the rotational speed of the DC motor 42 calculated from the counter electromotive voltage is obtained. Accordingly, since the supplied voltage is controlled, the rotational speed of the DC motor 42 can eliminate overshoot. Therefore, according to such a DC motor control device 41, the rotational speed of the DC motor 42 can be set to the target speed in a short time.

  Further, since the developing device 16 includes a DC motor control device 41 capable of setting the rotational speed of the DC motor 42 to a target speed in a short time, the toner is more stably developed using the toner supply rollers 32a to 32d. The images can be supplied into the containers 26a to 26d, and the quality of the image can be improved.

  Further, since the digital multi-function peripheral 10 includes the developing device 16 that can improve the image quality, the image quality can be improved.

  In the above embodiment, the DC motor control device controls the rotational speed of the DC motor that rotates the toner replenishing roller. However, the present invention is not limited to this, and other rotating members in the image forming apparatus, For example, the present invention may be applied when rotating a discharge roller for discharging a sheet, a pickup roller for picking up a sheet, or the like.

  In the above embodiment, the DC motor control unit provided in the DC motor control device is controlled by the control unit provided in the digital multi-function peripheral. Thus, it may be configured to control the rotational speed of the DC motor or the like.

  In the above embodiment, the rotational speed of the DC motor is calculated from the fed back counter electromotive voltage. However, the present invention is not limited thereto, and the counter electromotive voltage, the rotational speed of the DC motor corresponding to the counter electromotive voltage, and the like. And the voltage supplied to the DC motor may be controlled according to the rotational speed of the DC motor.

  In the above embodiment, the case of starting the DC motor has been described. However, the present invention is not limited to this, and the case where the rotational speed of the DC motor rotating in advance at a predetermined rotational speed is changed to a different rotational speed. Etc., etc.

  In the above embodiment, a full-color digital multifunction peripheral has been described. However, the present invention is not limited to this, and the present invention is also applicable to a monochrome digital multifunction peripheral.

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to the thing of embodiment shown in figure. Various modifications and variations can be made to the illustrated embodiment within the same range or equivalent range as the present invention.

1 is a block diagram illustrating an overall configuration of a digital multi-function peripheral including a developing device including a DC motor control device according to an embodiment of the present invention. It is the schematic which shows a part of developing apparatus. It is the schematic which shows the structure of a DC motor control apparatus. It is a flowchart which shows operation | movement in the case of controlling the rotational speed at the time of starting of a DC motor. It is a figure which shows the relationship between the setting of the voltage supplied to a DC motor, and the rotational speed of a DC motor. It is a figure which shows the relationship between the setting of the voltage supplied to the conventional DC motor, and the rotational speed of a DC motor. It is a figure which shows the relationship between the setting of the voltage supplied to the DC motor at the time of overshoot in the past, and the rotational speed of a DC motor.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Digital multifunction device, 11 Control part, 12 DRAM, 13 Operation part, 14 Document feeder, 15 Image reading part, 16 Developing apparatus, 17 Hard disk, 18 FAX communication part, 19 Network IF part, 20 Public line, 21 Network, 22 PC, 24 Cassette, 25a, 25b, 25c, 25d Photoconductor, 26a, 26b, 26c, 26d Developer, 27 Transfer belt, 28 Transfer section, 29 Discharge tray, 31a, 31b, 31c, 31d Developing sleeve, 32a, 32b, 32c, 32d Toner supply roller, 33a, 33b, 33c, 33d Toner hopper, 41 DC motor controller, 42 DC motor, 43 DC motor controller, 44 comparator, 45 PWM.

Claims (7)

A DC motor control device that rotates the DC motor at a predetermined rotational speed by supplying a voltage to the DC motor,
Voltage supply means for supplying a voltage higher than the voltage corresponding to the predetermined rotational speed to the DC motor;
Monitoring means for monitoring a back electromotive voltage generated by rotation of the DC motor;
Control means for controlling the voltage supplied by the voltage supply means so that the rotational speed of the DC motor does not exceed the predetermined rotational speed according to the counter electromotive voltage monitored by the monitoring means. DC motor control device. The DC motor control device according to claim 1, wherein the control means operates when the DC motor is started. 3. The DC motor control according to claim 1, wherein the control unit controls the voltage supply unit to lower the voltage than the high voltage when a rotation speed of the DC motor exceeds the predetermined rotation speed. 4. apparatus. 4. The DC according to claim 1, wherein the control unit controls the voltage supply unit to maintain the high voltage when a rotation speed of the DC motor does not exceed the predetermined rotation speed. 5. Motor control device. 5. The DC motor control apparatus according to claim 1, wherein the control unit includes a calculation unit that calculates a rotation speed of the DC motor from the counter electromotive voltage. A developing device that includes a DC motor and a rotating body that is rotated by the DC motor, and that supplies toner into a developing device that stores developer by rotation of the rotating body;
A developing device comprising the DC motor control device according to claim 1. An image forming apparatus comprising the developing device according to claim 6.

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