JP2010002708A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the start of first image forming operation from being delayed as much as possible by deciding the rotational speed of a polygon mirror in a short period of time in consideration of the using tendency of an image forming apparatus. <P>SOLUTION: The image forming apparatus includes: an exposure means that includes the polygon mirror; a control means that allows the polygon mirror selectively to rotate at first rotational speed and second rotational speed lower than the first rotational speed; and a mode selection means that selects either a first mode corresponding to formation of a monochrome image or a second mode corresponding to formation of a color image. The control means allows the polygon mirror to rotate at the first rotational speed when the first mode is selected by the mode selection means, and allows the polygon mirror to rotate at the second rotational speed when the second mode is selected by the mode selection means. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that includes an exposure unit including a polygon mirror and can selectively create a monochrome image and a color image.

  In an image forming apparatus in which a monochrome image and a color image are selectively created, the system speed (photosensitive member rotation speed, paper conveyance speed, etc.) is switched according to the type of image to be created (monochrome image or color image). Accordingly, the rotation speed of the polygon mirror as the exposure means can be switched. However, it takes time to raise the polygon mirror from the stationary state to the target speed, or to switch from the monochrome image rotation speed to the color image rotation speed or vice versa.

  Therefore, the waiting time at the start of printing can be reduced by always rotating the polygon mirror at a speed according to the image stabilization processing for monochrome image or color image performed when the image forming apparatus is started. Proposed. However, a reduction in CPP (cost per printed sheet) is also required, and image stabilization processing is not always performed when the image forming apparatus is activated. For this reason, even if the rotational speed of the polygon motor is determined in accordance with the operation of the image stabilization process, the image stabilization process may not be performed. For different types of image printing, the polygon motor speed must be switched from monochrome printing to color printing or from color printing to monochrome printing. As a result, there is a delay in the start of the printing operation, which causes the user to wait.

  A user who mainly performs color printing is expected to perform more color image stabilization processing than monochrome image stabilization processing. On the contrary, if the user mainly performs monochrome printing, it is expected that more monochrome image stabilization processing will be executed than color image stabilization processing. Therefore, the present invention provides a mode for preferentially performing either monochrome or color image stabilization processing, and if the mode is set to preferentially perform monochrome image stabilization processing, the speed for monochrome printing is set. If the mode is set so that the polygon mirror is always rotated and the color image stabilization process is performed preferentially, the polygon mirror can be rotated quickly at the speed for color printing. The rotation speed is set so that the start of printing can be accelerated.

  In order to achieve this object, the present invention selectively rotates an exposure means having a polygon mirror and the polygon mirror at two speeds of a first rotation speed and a second rotation speed that is slower than the first rotation speed. In the image forming apparatus including the control unit, the control unit selects either the first image stabilization mode corresponding to creation of a monochrome image or the second image stabilization mode corresponding to creation of a color image. When the first image stabilization mode is selected by the mode selection means and the mode selection means, the polygon mirror is rotated at the first rotation speed, and the second image stabilization mode is selected by the mode selection means. In some cases, there is a speed setting means for rotating the polygon mirror at the second rotation speed.

  According to the present invention, in an image forming apparatus in which monochrome image stabilization processing or monochrome printing is preferentially executed as the first job after the image forming apparatus is started, the stabilization execution mode for monochrome images is selected. By doing so, the polygon motor can be driven at a rotational speed in accordance with monochrome printing, and monochrome printing can be started quickly. Further, in an image forming apparatus in which color image stabilization processing or color printing is preferentially executed as the first job after the image forming apparatus is started, by selecting a color image stabilization execution mode, Color printing can be started quickly by driving the polygon motor at a rotational speed that matches color printing.

  Embodiments of an image forming apparatus according to the present invention will be described below with reference to the accompanying drawings.

[1. Configuration and operation of image forming apparatus]
The configuration and operation of the image forming apparatus will be briefly described with reference to the drawings. Note that the present invention can be applied to a plurality of image forming apparatuses such as a printer, a copier, a multifunction peripheral, and a facsimile machine. However, in order to simplify the description, an example in which the present invention is applied to a printer will be described below. .

  Referring to FIG. 1, the printer 10 is a full color printer. When the printer 10 forms a full-color image, light corresponding to images of four colors (yellow, magenta, cyan, and black) is provided to the four image forming units 14 from the print head 12 that is an exposure unit. For example, image forming units having yellow, magenta, cyan, and black developers are sequentially arranged from the left side to the right side of the figure. As is well known, the image forming unit 14 includes a photoconductor, a developing device, a charger, and the like, and the photoconductor 16 of the image forming unit 14 corresponding to the four color images output from the print head 12 (see FIG. 2). ) Is exposed. In each image forming unit 14, the photosensitive member 16 is charged to a predetermined potential before exposure, and an image is exposed to the charged region to form an electrostatic latent image. The electrostatic latent image is visualized by a developer (toner) provided from a developing device. The developer image created by each image forming unit 14 is transferred to and superposed on the outer peripheral surface of the transfer belt 18 that is an intermediate transfer member to obtain a full-color developer image. The full-color developer image is conveyed along with the rotation of the transfer belt 18, and is transferred to the sheet fed from the paper feed unit 22 in an area where the transfer belt 18 and the transfer device 20 face each other. The sheet on which the developer image has been transferred is conveyed to the fixing device 24 where the developer image is fixed to the sheet and then discharged to the discharge unit 26.

[2. Print head)
Referring to FIG. 2, the print head 12 has laser diodes 28 that are four light sources corresponding to four colors. The light output from each laser diode 28 is applied to the outer peripheral surface of a polygon mirror 30 which is a hexagonal rotary polygon mirror. The polygon mirror 30 is drivingly connected to a motor (polygon motor) 32 capable of adjusting the rotation speed, and rotates in a predetermined direction based on the driving of the polygon motor 32. As a result, the light applied to the outer peripheral surface of the polygon mirror 30 is scanned on the photosensitive member 16 via the lenses 34 and 36, the reflection mirrors 38 and 40, the lens 42, and the reflection mirror 44, thereby forming an electrostatic latent image. Form. The polygon motor 32 is connected to the control means 50 described in detail later, and rotates the polygon mirror 30 at a speed set by the control device (control means) 50.

[3. Control block)
FIG. 3 is a block diagram illustrating a configuration of the control device 50. As illustrated, the control device 50 includes an engine control unit 52 and a printer controller 54. The printer controller 54 controls the RAM 56, HDD 58, scanner 60, facsimile interface (FAX IF) 62, and operation panel 64. The printer controller 54 is capable of serial communication with the engine control unit 52, provides image data to the engine control unit 52 through an image bus, and exchanges data with computers (PCs) 66 and 68 via a LAN. The RAM 56 and the HDD 58 are storage media. The RAM 56 is excellent in terms of transfer speed, and the HDD 58 is excellent in terms of storage capacity, although it is inferior to the RAM 56 in terms of transfer speed. The scanner 60 reads document information and generates image data corresponding to the read information. The facsimile interface 62 executes facsimile transmission / reception of image data. The operation panel 64 includes a touch panel and push button keys as hardware. The operation panel 64 displays to the user and receives an input operation from the user. A stabilization execution mode described later is set by an input from the operation panel 64. The engine control unit 52 controls the print head 12. The print head 12 includes a polygon motor 32 and a laser diode 28, and performs polygon motor control such as starting, stopping, and monitoring of rotation of the polygon motor 32. Further, the engine control unit 52 switches on / off the laser diode 28 according to the image data supplied from the printer controller 54, and forms an electrostatic latent image on the photoconductor 16. Further, the engine control unit 52 performs the laser emission amount on the backup memory (ROM) 66, the absolute humidity when the previous image stabilization process is performed, and the temperature within the print head 12 when the previous image stabilization process is performed. Various data such as are stored.

[4. (Image stabilization processing)
Hereinafter, the image stabilization processing of the control device 50 will be described with reference to the drawings.

  Image stabilization is a process where the color and density of the printed image changes due to changes in various characteristics such as photoreceptor characteristics, development characteristics, and charging characteristics due to environmental conditions and durability conditions. In order to prevent the image from being damaged, it is a general term for a process for stabilizing the image by suppressing fluctuations in these characteristics. Image stabilization processing includes printing laser light amount correction processing, toner density correction processing, γ characteristic detection correction processing, and resist correction processing. FIG. 13 is a diagram illustrating a print pattern used for the resist correction process.

[4.1: Stabilization mode]
Referring to FIG. 4, the image stabilization process has a stabilization execution mode. The stabilization execution mode is a mode that is set by a user or a serviceman by operating a switch 68 (see FIG. 1) or a button of mode selection means provided on the operation panel 64 (see FIG. 1) of the image forming apparatus. There are two modes-mode 1 and mode 2-. Mode 1 is a mode for users who use the printer 10 mainly for monochrome printing. Therefore, in the state where mode 1 is selected, when there is a factor for performing the image stabilization process at the time of starting the image forming apparatus, the image stabilization process for monochrome printing is preferentially performed. Mode 2 is a direction mode for users who mainly use color printing. Therefore, in the state where mode 2 is selected, when there is a factor for performing the image stabilization process at the time of starting the image forming apparatus, the image stabilization process for color printing is preferentially performed.

[4.2: Polygon mirror rotation speed setting]
Referring to FIG. 5, the polygon motor is activated in two ways: when the image forming apparatus is activated, and when the interrupted image forming process is resumed when the image forming process is interrupted due to a trouble such as a jam. It is done at the timing.

  When the image forming apparatus is activated, the rotation speed is determined using the image stabilization execution mode as an index. Specifically, if mode 1 is selected, there is a high possibility that monochrome printing and monochrome printing image stabilization processing will be performed, so the polygon motor 32 is rotated at the rotation speed for monochrome printing. If mode 2 is selected, there is a high possibility that color printing is selected. Therefore, it is expected that the image stabilization process is highly likely to be performed as a color image stabilization process. Therefore, when the mode 2 is selected, the polygon motor 32 is rotated at the rotation speed for color printing.

  When the polygon motor 32 is started again due to a trouble and then the polygon motor 32 is started again to resume the suspended job, the polygon motor 32 is driven at the same speed as before the polygon motor 32 stopped regardless of the image stabilization execution mode. . When the interrupted image forming process is resumed by rotating the polygon motor 32 at the same speed as before the stop, there is no extra waiting time associated with the rotation speed switching.

[4.3: Conditions for performing image stabilization processing]
Referring to FIG. 6, the conditions for performing the image stabilization process when the image forming apparatus is activated are that it is detected that a new image forming unit is mounted on the image forming apparatus, and the time point of the previous image stabilization process. That the absolute humidity has changed by 3 steps (predetermined humidity range) or more based on the detection of the sensor in the image forming apparatus, and the temperature in the print head 12 is 2 ° C. or more from the time of the previous image stabilization process. There was a change. When any one of the image forming units or the intermediate transfer belt is replaced with a new one, the color long stabilization process having a long pattern length is performed regardless of the stabilization execution mode. When the absolute humidity changes by 3 steps or more from the time of the last image stabilization process, the transfer efficiency and the toner adhesion amount have changed from the previous image stabilization process. To implement. When the stabilization execution mode is set to mode 1, since the user who creates an image is used mainly for monochrome printing, the monochrome image stabilization is performed. When the mode 2 is set, the color image stabilization is performed because the user who creates an image mainly uses color printing. When the temperature in the print head 12 changes since the previous image stabilization, the lens in the print head is distorted and color misregistration occurs. Registration control is performed to correct the color misregistration. When the stabilization execution mode is set to mode 1, registration control is not executed because there is no need to correct color misregistration in monochrome printing. When mode 2 is set, color printing is frequently performed, so it is necessary to perform color misregistration correction.

[5. Control of polygon motor)
The rotation speed control of the polygon motor by the control means will be specifically described.

[5.1: Processing at startup of image forming apparatus]
Referring to FIG. 7, in the control of the polygon motor accompanying the activation of the image forming apparatus, power is supplied to the polygon motor 32 in step (hereinafter indicated by the symbol “S”) 60 when the image forming apparatus is activated. Check if it is in a state. If the power for starting the polygon motor 32 is not supplied, the polygon motor 32 cannot be started. Therefore, the system waits until power is supplied. If the electric power is supplied, start control of the polygon motor 32 is executed (S61). Next, when the polygon motor 32 is activated and its rotational speed reaches a predetermined stable rotational speed, image stabilization control is performed (S62). In image stabilization control, it is determined whether or not image stabilization processing is to be performed. If so, the type of stabilization (monochrome stabilization processing, color stabilization processing, color long, normal color) is determined, and the image Perform stabilization processing. When the image stabilization process ends, print control is executed (S63).

[5.2: Polygon motor start control]
In the embodiment, the polygon motor 32 is a stepping motor. Therefore, the polygon motor 32 rotates in synchronization with the polygon motor control CLK (clock). When the polygon motor control CLK advances one pulse, it rotates by one step. That is, the polygon motor 32 rotates at a higher speed as the value of the polygon motor control CLK is larger. Normally, the monochrome printing speed (polygon mirror rotation speed) is set faster than the color printing speed (polygon mirror rotation speed). For example, the polygon motor control CLK is set to 2,100 Hz for monochrome printing, and the polygon motor control CLK is set to 1,600 Hz for color printing.

  Therefore, in the startup control of the polygon motor 32, first, the user selection mode is confirmed (S70). If the operation mode is set to mode 1, since the user is mainly monochrome, the polygon motor control CLK is set to a monochrome printing value (2,100 Hz) (S71). If the user selection mode is set to mode 2, the polygon motor control CLK is set to a value for color printing (1,600 Hz) (S72). Next, the polygon motor remote (start signal) is set to ON and the polygon motor 32 is started (S73). Subsequently, it is confirmed whether the polygon motor 32 has reached a stable rotational speed (rotational speed corresponding to CLK) (S74). If the polygon motor 32 has not reached the stable rotational speed, the process waits until the rotational speed is reached. When the polygon motor 32 reaches the stable rotational speed, the startup control of the polygon motor 32 is completed.

[5.3: Image stabilization control]
Referring to FIG. 9, in the image stabilization control, it is determined whether the image forming unit 14 or the intermediate transfer belt 18 is new (S80). If the image forming unit 14 or the intermediate transfer belt 18 is new, a long pattern color long stabilization process is performed (S81). If the image forming unit 14 or the intermediate transfer belt 18 is not new, is there a predetermined width (3 steps) difference between the absolute humidity when the image stabilization process was last performed and the current absolute humidity? It is determined whether or not (S82). When a change of 3 steps or more is confirmed in the absolute humidity, the set stabilization execution mode is confirmed, and the type of stabilization processing to be executed is determined (S83). When the stabilization execution mode is set to mode 2, the normal color stabilization process is performed (S84). When the stabilization execution mode is set to mode 1, monochrome normal stabilization processing is performed (S85). If a change of 3 steps or more is not confirmed in the absolute humidity, a difference of a predetermined width (2 ° C.) determined in advance between the temperature in the print head unit and the current temperature when the last stabilization process was performed. It is determined whether or not there is (S86). If the temperature has changed by 2 ° C. or more since the last stabilization process, it is recognized that the temperature has changed. When the temperature change is 2 ° C. or more and the stabilization execution mode is mode 2, registration control is performed in order to perform color misregistration correction (S87, S88). When the temperature change is less than 2 ° C. or when the stabilization execution mode is mode 1, the stabilization process is not performed.

[5.4: Polygon motor stop control]
FIG. 10 shows control for stopping the polygon motor when a factor (for example, jam) that interrupts the image forming operation occurs. According to this control, when the image forming operation is interrupted due to some trouble during image formation, the image formation is stopped and the polygon motor 32 is stopped. For example, when a jam occurs during image formation (S90), the current frequency set in the polygon motor control CLK is saved (S91). In the image forming process after the trouble is released, the frequency stored here is set in the polygon motor control CLK. Next, the polygon motor remote (activation signal) is turned off to stop the polygon motor 32 (S92), and the polygon motor control CLK is set to 0 Hz (S93).

[5.5: Polygon motor restart control]
FIG. 11 shows control for restarting the polygon motor after the trouble is solved. According to this control, when a trouble (for example, jam) that interrupts image formation is resolved (S100), the value set in the polygon motor control CLK before the polygon motor 32 stops is again set to the polygon motor control. Set to CLK (S101). Next, the polygon motor remote is turned on to restart the polygon motor 32 (S102). When the polygon motor 32 is activated, it is determined whether or not the rotational speed of the polygon motor 32 has reached a stable rotational speed corresponding to the polygon motor control CLK with reference to the lock signal of the polygon motor 32 (S103). If the rotation speed of the polygon motor 32 is not stable, the process waits. If the rotation speed of the polygon motor 32 is stable, the stopped image forming process is resumed (S104).

[5.6: Startup sequence]
The polygon motor activation control described above will be described in comparison with the conventional activation control. FIG. 12A shows a conventional startup sequence, and FIG. 12B shows a startup sequence of the present invention. Now, in the conventional activation sequence, the polygon motor is uniformly activated at the speed of the color image stabilization process. On the other hand, in the startup sequence of the present invention, it is assumed that mode 1 is selected as the stabilization execution mode.

  In this case, in the conventional startup sequence, when the timing P1-1 for starting the polygon motor is reached, the polygon motor is uniformly started at the color speed and waits until the rotation of the polygon motor is stabilized. The determination of whether or not the rotation is stable is regarded as a stable rotation state if, for example, the lock signal of the polygon motor is locked for a predetermined time. When the polygon motor reaches a stable rotational speed (P1-2), color printing becomes possible, and the system waits until a printing instruction is input. When a monochrome stabilization process command is received during standby (P1-3), the polygon motor speed is changed from the color printing image stabilization process speed (CLK = 1,600 Hz) to monochrome to execute the monochrome stabilization process. Switching to the printing image stabilization processing speed (CLK = 2, 100 Hz). When the rotation speed of the polygon motor is switched, a waiting time is generated until the rotation speed reaches a stable value again, and the image stabilization process for monochrome printing can be started only when the stable rotation is reached later (P1-4). Therefore, it takes T1 time from when the polygon motor is activated (P1-1) to when the monochrome printing image stabilization process is executed (P1-4) before the monochrome stabilization process is actually started.

  On the other hand, according to the activation sequence of the present invention, when the polygon motor is activated (P2-1), the activation speed of the polygon motor is determined with reference to the stabilization execution mode. Accordingly, when mode 1 is selected as the stabilization execution mode, the polygon motor is started up at the monochrome printing image stabilization processing speed. As a result, printing becomes possible when the polygon motor reaches a stable rotational speed (P2-2), and the system waits until a printing instruction is received. As a result, when a monochrome stabilization command is received during standby, the image stabilization process for monochrome printing can be executed immediately at that time, and the image stabilization process for monochrome printing is executed from the time when the polygon motor is started (P2-1). The time (T2) becomes a waiting time until the time point (P2-3) to be performed, and the time (T2) is greatly shortened compared to the waiting time (T1) of the conventional activation sequence shown in FIG. 12A.

  As described above, according to the present invention, in an image forming apparatus in which monochrome image stabilization processing or monochrome printing is preferentially executed as the first job after the image forming apparatus is started up, stabilization for monochrome images is performed. By selecting the execution mode, the polygon motor can be driven at a rotational speed in accordance with monochrome printing, and monochrome printing can be started quickly. Further, in an image forming apparatus in which color image stabilization processing or color printing is preferentially executed as the first job after the image forming apparatus is started, by selecting a color image stabilization execution mode, Color printing can be started quickly by driving the polygon motor at a rotational speed that matches color printing.

1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus (printer). FIG. 3 is a diagram illustrating a configuration of a print head. FIG. 3 is a control block diagram of the image forming apparatus. The figure explaining the stabilization implementation mode, the object user of each mode, and the stabilization kind at the time of machine starting. The figure explaining the polygon motor rotational speed for every stabilization implementation mode. The figure explaining the stabilization implementation conditions. The figure which shows the control of the polygon motor at the time of image forming apparatus starting. The figure which shows polygon motor starting control. The figure which shows the control according to image stabilization implementation mode. The figure which shows the polygon motor control at the time of printing operation interruption. The figure which shows the polygon motor control at the time of printing operation return. The figure explaining the conventional starting sequence and the starting sequence of this invention. The figure which illustrates the pattern to be used for registration correction.

Explanation of symbols

10: printer 12: print head 14: image forming unit 16: photoconductor 18: transfer belt 20: transfer device 22: paper feeding unit 24: fixing unit 26: discharge unit 30: polygon mirror 52: engine control unit 54: printer controller 68: Switch (mode selection means)

Claims (8)

Exposure means having a polygon mirror;
Control means for selectively rotating the polygon mirror at two speeds of a first rotation speed and a second rotation speed lower than the first rotation speed;
In an image forming apparatus including a mode selection unit capable of selecting either a first mode corresponding to creation of a monochrome image or a second mode corresponding to creation of a color image,
The control means includes
When the first mode is selected by the mode selection means, the polygon mirror is rotated at a first rotation speed, and when the second mode is selected by the mode selection means, the second rotation speed is used. An image forming apparatus characterized by rotating a polygon mirror. The control means includes
2. The image forming apparatus according to claim 1, wherein when an event that interrupts the rotation of the polygon mirror occurs during the rotation of the polygon mirror, the polygon mirror is rotated at a rotation speed selected before the occurrence of the event. apparatus.   3. The image forming apparatus according to claim 1, wherein the control unit rotates the polygon mirror at the first rotation speed or the second rotation speed according to the selection of the mode selection unit when the image forming apparatus is activated. apparatus. And further comprising a stabilizing means for performing image stabilization processing,
The stabilization unit is configured to perform image stabilization when the absolute humidity in the image forming apparatus has a predetermined change when the image forming apparatus is started, as compared with the previous image stabilization process performed by the stabilization unit. Execution process,
The image forming apparatus according to claim 1, wherein the control unit rotates the polygon mirror at the first rotation speed or the second rotation speed in accordance with the selection of the mode selection unit. In an image forming apparatus including an exposure unit having a polygon mirror,
When the first mode is selected by the mode selection means, the polygon mirror is rotated at the first rotation speed, and when the second mode is selected by the mode selection means, the rotation speed is higher than the first rotation speed. An image forming method, wherein the polygon mirror is rotated at a slow second rotation speed.   6. The image forming method according to claim 5, wherein when an event that interrupts the rotation of the polygon mirror occurs during the rotation of the polygon mirror, the polygon mirror is rotated at a rotation speed selected before the occurrence of the event. Method.   7. The image forming method according to claim 5, wherein when the image forming apparatus is activated, the polygon mirror is rotated at the first rotation speed or the second rotation speed in accordance with the selection of the mode selection means. When the image forming apparatus is started up, when there is a predetermined change in the absolute humidity in the image forming apparatus as compared to the previous execution of the image stabilization process, the image stabilization process is executed.
The image forming method according to claim 5, wherein the polygon mirror is rotated at the first rotation speed or the second rotation speed in accordance with the selection of the mode selection unit.

Images