JP2008026792A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the frequency of turning on/off a polygon mirror, and to shorten a startup time. <P>SOLUTION: A CPU 212 includes: a polygon driving part 212f to control the drive of a polygon motor 512M for driving the polygon mirror; a main driving part 212g to control the drive of a conveying motor 54M for conveying a recording paper; a rotation judging part 212b to judge whether or not the polygon mirror is rotated at a rotating speed higher than a preset rotating speed (for example, 70% of the rotating speed in a stable rotation state); and a drive control part 212e to instruct the polygon driving part 212f and the main driving part 212g to start/stop the drive thereof based on the judgement result by the rotation judging part 212b. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that forms a latent image by irradiating a photosensitive drum with a laser beam via a polygon mirror and forms a toner image corresponding to the formed latent image on a recording sheet. In particular, the present invention relates to a copying machine, a printer, a facsimile machine, an Internet facsimile machine, and a multifunction machine having any one of these functions.

  2. Description of the Related Art In recent years, a copying machine or facsimile (so-called electrophotographic system) that forms a latent image by irradiating a photosensitive drum with a laser beam through a polygon mirror and forms a toner image corresponding to the formed latent image on a recording sheet. In an image forming apparatus such as an apparatus, since a power supply capacity is not sufficiently large, a motor that rotates a polygon mirror (hereinafter referred to as a polygon motor), a motor that drives a photosensitive drum or the like (hereinafter referred to as a main motor), May not be started at the same time. In such a case, there is a problem that the startup time becomes long.

In order to solve the above problem, the polygon motor is driven for a predetermined time before starting the main motor, and then the drive is stopped at one end. A shortening printer has been proposed (see Patent Document 1).
Japanese Patent No. 3501502

  However, although it is possible to shorten the start-up time in the printer, the polygon motor life may be shortened because the frequency of starting and stopping (on / off) of the polygon motor increases.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of suppressing the on / off frequency of a polygon motor and shortening the startup time.

  In order to achieve the above object, an image forming apparatus according to claim 1 forms a latent image by irradiating a photosensitive drum with a laser beam through a polygon mirror, and forms a toner image corresponding to the formed latent image. An image forming apparatus for forming on a recording sheet, wherein the polygon driving unit drives the polygon mirror, the main driving unit drives at least the photosensitive drum, and the polygon mirror rotates at a speed higher than a preset rotational speed. Rotation determining means for determining whether or not there is, and drive control means for instructing the polygon driving means and the main driving means to start and stop driving based on the determination result by the rotation determining means. It is a feature.

  The image forming apparatus according to claim 2 is the image forming apparatus according to claim 1, wherein the rotation determination unit has elapsed time from the time when the polygon driving unit is changed from the driving state to the driving stop state. Based on the above, it is characterized by determining whether or not the rotation speed is higher than a preset rotation speed.

  An image forming apparatus according to a third aspect is the image forming apparatus according to the second aspect, wherein the rotation determining unit is equal to or higher than a preset rotation speed when the elapsed time is shorter than a preset threshold value. It is characterized by determining that it is rotating.

  An image forming apparatus according to a fourth aspect is the image forming apparatus according to the third aspect, further comprising a threshold setting unit configured to set the threshold based on an acceleration characteristic of the polygon driving unit.

  An image forming apparatus according to a fifth aspect is the image forming apparatus according to the fourth aspect, further comprising a fixing roller for fixing the toner image onto the recording paper, wherein the threshold value setting means adjusts the heating characteristic of the fixing roller. The threshold value is set based on this.

  An image forming apparatus according to a sixth aspect is the image forming apparatus according to the fifth aspect, further comprising a reception unit that receives an instruction to form an image on a recording sheet, and the drive control unit includes the rotation determination unit. When it is determined that the vehicle does not rotate at a rotation speed set in advance by the means, when the instruction is received by the receiving means, the polygon driving means is started to drive, and a preset stop is made. At the timing, the polygon driving means is stopped and the main driving means is started. Further, when the main driving means is in a stable driving state, the polygon driving means is stopped. And driving is started.

  An image forming apparatus according to a seventh aspect is the image forming apparatus according to the sixth aspect, further comprising a temperature determining unit that determines whether or not a temperature of the fixing roller is equal to or higher than a preset temperature. The drive control unit sets the timing at which the temperature determination unit determines that the temperature of the fixing roller is equal to or higher than a preset temperature as the stop timing.

  An image forming apparatus according to an eighth aspect is the image forming apparatus according to the seventh aspect, wherein the drive control unit is determined to be rotating at a rotation speed or higher set in advance by the rotation determining unit. In this case, after the instruction is received by the receiving unit, the main driving unit is driven when the temperature determining unit determines that the temperature of the fixing roller is equal to or higher than a preset temperature. The polygon driving means is started to drive when the main driving means is in a stable driving state.

  According to the image forming apparatus of the first aspect, the polygon driving means for driving the polygon mirror and at least the photosensitive drum are driven based on the determination result as to whether or not the polygon mirror is rotating at a preset rotation speed or higher. Since the driving start and stop are instructed to the main driving means to be driven, it is possible to suppress the on / off frequency of the polygon motor and to shorten the startup time.

  That is, for example, when the polygon mirror is rotating at a preset rotation speed or higher, first, the main drive means is driven, and when the main drive means is in a stable drive state, the polygon drive means Thus, the frequency of turning on / off the polygon motor can be suppressed by starting the driving. For example, when the polygon mirror is rotating at a speed lower than a preset rotation speed, the polygon mirror is first driven to drive the main driving means at a predetermined timing and to the polygon driving means with respect to the polygon. The starting time can be shortened by stopping the driving of the mirror and starting the driving of the polygon driving means when the main driving means is in a stable driving state.

  According to the image forming apparatus of the second aspect, the polygon mirror rotates at a predetermined rotation speed or higher based on the elapsed time from the time when the polygon driving unit is changed from the driving state to the driving stop state. Therefore, it is not necessary to detect the rotational speed of the polygon mirror, and the apparatus can be simplified.

  The rotational speed of the polygon mirror in the stable drive state is a preset speed, and the relationship between the elapsed time from the time when the stable drive state is changed to the drive stop state and the rotational speed of the polygon mirror is Since it is uniquely determined by the device configuration, it is accurately determined whether or not the polygon mirror is rotating at a preset rotation speed or higher based on the elapsed time from when the polygon driving means is changed from the driving state to the driving stop state. can do.

  According to the image forming apparatus of the third aspect, when the elapsed time from the time when the driving state is changed to the driving stop state is shorter than a preset threshold value, the image forming apparatus rotates at a preset rotational speed or more. Therefore, it can be accurately determined with a simple configuration.

  According to the image forming apparatus of the fourth aspect, since the threshold value of the elapsed time is set based on the acceleration characteristic of the polygon driving unit, it is possible to set an appropriate threshold value. In other words, the better the acceleration characteristics of the polygon driving means, the greater the threshold value, so that the frequency of turning on and off the polygon motor can be suppressed and the startup time can be shortened.

  According to the image forming apparatus of the fifth aspect, since the threshold value of the elapsed time is set based on the heating characteristic of the fixing roller, an appropriate threshold value can be set. In other words, the better the heating characteristics of the fixing roller, the greater the threshold value, so that the frequency of turning on and off the polygon motor can be suppressed and the startup time can be shortened.

  According to the image forming apparatus of claim 6, when it is determined that the polygon mirror is not rotating at a preset rotation speed or higher, an instruction to form an image on a recording sheet is received. Then, the driving of the polygon driving means is started, and at the preset stop timing, the driving of the polygon driving means is stopped, the driving of the main driving means is started, and the main driving means is in a stable driving state. Since the driving of the polygon driving means is started at this point, the activation time can be shortened.

  That is, for example, the polygon mirror is accelerated to some extent when the driving of the main driving means is started by pre-driving the polygon driving means until the temperature of the fixing roller reaches a preset temperature or higher. The start-up time can be shortened.

  According to the image forming apparatus of the seventh aspect, when the temperature of the fixing roller is determined to be equal to or higher than a preset temperature, the driving of the polygon driving unit is stopped and the driving of the main driving unit is performed. Since the polygon mirror is accelerated to some extent at the start of driving of the main drive means, the activation time can be shortened.

  According to the image forming apparatus of claim 8, after it is determined that the polygon mirror is rotating at a speed higher than a preset rotation speed, an instruction to form an image on a recording sheet is received. When it is determined that the temperature of the fixing roller is equal to or higher than a preset temperature, the driving of the main driving unit is started, and the driving of the polygon driving unit is started when the main driving unit is in a stable driving state. Therefore, the frequency of turning on / off the polygon motor can be suppressed.

  Hereinafter, an example of an image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an example of a schematic configuration of an image forming apparatus according to the present invention. Although the case where the image forming apparatus is a copying machine will be described here, a latent image is formed by irradiating the photosensitive drum with a laser beam from a laser diode through a polygon mirror. Other forms of image forming apparatuses (for example, facsimile machines, Internet facsimile machines, printers, multifunction machines, etc.) that form toner images corresponding to the above on recording paper may be used. As shown in FIG. 1, the copier 100 includes an image generation unit 1, a control unit 2, a display unit 3, an operation unit 4, and a print processing unit 5.

  The image generation unit 1 reads an image formed on a document and generates document image information, and includes a reading unit 11 and an ADF 12. The reading unit 11 illuminates a document to be read and reads reflected light with a CCD (Charge Coupled Devices) or the like to generate document image information. An ADF (Automatic Document Feeder) 12 conveys a document to a document reading position of the reading unit 11.

  The control unit 2 controls the operation of the entire copying machine 100, and includes a CPU (Central Processing Unit) 21, a RAM (Random Access Memory) 22, and a ROM (Read Only Memory) (not shown). Yes.

  The display unit 3 includes an LCD (Liquid Crystal Display), an LED (Light Emitting Diode), and the like, and displays setting information, guidance information, message information, and the like so as to be visible to the user based on instructions from the control unit 2 (CPU 21). To do.

  The operation unit 4 (corresponding to a part of the accepting unit) accepts an operation input from the user, generates operation input information corresponding to the accepted operation input, and outputs the operation input information to the control unit 2 (CPU 21). is there. The operation unit 4 includes, for example, various buttons such as a numeric keypad and a start button, and a touch panel formed integrally with the LCD disposed in the display unit 3.

  The print processing unit 5 forms an image on a recording sheet by an electrophotographic method (here, an image corresponding to the image information generated by the image generation unit 1), and includes a developing unit 51, a photosensitive unit 52, a fixing unit. A unit 53 and a transport unit 54 are provided. The development unit 51 forms an electrostatic latent image corresponding to the original image generated by reading the image formed on the original on the surface of the photosensitive drum by the laser beam emitted from the laser diode 511. A toner image is formed by attaching toner to an electrostatic latent image.

  The photosensitive unit 52 includes a photosensitive drum 521. First, the surface of the photosensitive drum 521 is substantially uniformly charged by a charging roller, and then toner is attached to the electrostatic latent image corresponding to the document image by the developing unit 51. Thus, a toner image is formed, and the toner image is further transferred onto a recording sheet by a transfer roller.

  The fixing unit 53 includes a fixing roller 531 and fixes the toner image transferred to the recording paper. The fixing roller 531 is provided with a temperature sensor (not shown) at an appropriate position, is controlled to a predetermined temperature (for example, 180 ° C.), and heats and fixes the toner image transferred to the recording paper.

  The transport unit 54 includes a transport motor 54 </ b> M (corresponding to a part of the main drive unit), and transports the recording paper along a predetermined transport path that passes through the photosensitive unit 52 and the fixing unit 53. The recording sheet is first conveyed to the photosensitive unit 52 by the conveyance unit 54, and the toner image is transferred from the photosensitive drum 521. Then, the toner image is conveyed to the fixing unit 53 by the conveying unit 54, and the toner image is heated and fixed.

  FIG. 2 is a configuration diagram showing an example of the configuration of the developing unit 51 shown in FIG. The developing unit 51 includes a polygon mirror 512 and an fθ lens 513 in addition to the laser diode 511 shown in FIG. The laser beam emitted from the laser diode 511 is incident on the polygon mirror 512. Here, the polygon mirror 512 is a regular hexagon, and is driven by a polygon motor 512M (corresponding to a part of the polygon driving means) and rotates at a constant speed clockwise, but the polygon mirror 512 is a regular hexagon. However, other shapes may be used as long as they are regular polygons. Further, the rotation direction and rotation speed of the polygon mirror 512 can be appropriately set according to the specifications of the apparatus.

  The laser beam reflected by the polygon mirror 512 is incident on the fθ lens 513 and converted to a constant velocity, and forms an image on the photosensitive drum 521 through the mirror 514 as a beam spot. In this way, the laser beam is scanned in the main scanning direction (upper right direction in FIG. 2) of the photosensitive drum 521.

  FIG. 3 is a functional configuration diagram showing an example of the functional configuration of the main part in the present invention. 1 functionally includes a threshold setting unit 212a, a rotation determination unit 212b, a reception unit 212c, a temperature determination unit 212d, a drive control unit 212e, a polygon drive unit 212f, and a main drive unit 212g. .

  Here, the CPU 21 reads and executes a program stored in advance in a ROM or the like, whereby a threshold setting unit 212a, a rotation determination unit 212b, a reception unit 212c, a temperature determination unit 212d, a drive control unit 212e, and a polygon drive unit 212f. And, it functions as a functional unit such as the main drive unit 212g.

  Of various data stored in the RAM 22 and ROM, data that can be stored in a removable recording medium is, for example, a driver such as a hard disk drive, an optical disk drive, a flexible disk drive, a silicon disk drive, or a cassette medium reader. In this case, the recording medium is, for example, a hard disk, an optical disk, a flexible disk, a CD, a DVD, a semiconductor memory, or the like.

  The threshold setting unit 212a (corresponding to the threshold setting unit) is configured so that the polygon mirror 512 is not less than a preset rotation speed based on the acceleration characteristics of the polygon motor 512M, the heating characteristics of the fixing roller 531 and the deceleration characteristics of the polygon mirror 512. A threshold value T0 for determining whether or not the object is rotating is set.

  The acceleration characteristics of the polygon motor 512M are required, for example, until the polygon motor 512M reaches the polygon mirror 512 from a stopped state to a stable rotation state (a state where the polygon motor 512 rotates at a required rotation speed when printing is performed). The threshold value setting unit 212a sets the threshold value T0 to be smaller as the acceleration time is longer. The shorter the acceleration time, the better the acceleration characteristics of the polygon motor 512M. The acceleration time is, for example, 3 seconds.

  The heating characteristic of the fixing roller 531 is, for example, the time required for the fixing roller 531 to reach a predetermined temperature (for example, a temperature required for printing: 180 ° C.) from normal temperature (for example, 30 ° C.). The threshold value setting unit 212a sets the threshold value T0 to be smaller as the heating time is longer. Note that the shorter the heating time, the better the heating characteristics of the fixing roller 531.

  Further, the deceleration characteristic of the polygon mirror 512 is, for example, that the polygon mirror 512 is in a stable rotation state (a state where the polygon mirror 512 is rotating at a required rotation speed when printing is performed) to a predetermined rotation speed (for example, a stable rotation state). (The rotation speed of 70% of the rotation speed in FIG. 4) is represented by the time to be decelerated (hereinafter referred to as the deceleration time). The longer this deceleration time, the larger the threshold setting unit 212a sets the threshold T0. is there. The longer the deceleration time, the better the deceleration characteristics of the polygon mirror 512.

  The rotation determination unit 212b (corresponding to a rotation determination unit) determines whether or not the polygon mirror 512 is rotating at a rotation speed higher than a preset value. Here, the rotation determination unit 212b is configured such that the elapsed time from when the polygon motor 512M is changed from the driving state (= on) to the driving stop state (= off) is equal to or less than the threshold T0 set by the threshold setting unit 212a. In some cases, it is determined that the polygon mirror 512 is rotating at a rotation speed higher than a preset rotation speed (for example, 70% of the rotation speed in a stable rotation state).

  Here, the rotation determination unit 212b indicates whether the polygon mirror 512 is rotating at a rotation speed of 70% or more of the rotation speed in the stable rotation state, depending on whether the polygon rotation flag is on or off. (See FIG. 5). That is, when the polygon rotation flag is on, it indicates that the polygon mirror 512 is rotating at a rotation speed of 70% or more of the rotation speed in the stable rotation state, and when the polygon rotation flag is off, the polygon mirror 512 represents that it is rotating at a rotation speed of less than 70% of the rotation speed in the stable rotation state.

  The accepting unit 212c (corresponding to a part of accepting means) accepts an operation input from the user via the operation unit 4, and accepts an instruction to form an image on recording paper based on the accepted operation input. Is. Specifically, the reception unit 212c receives an instruction to form an image on a recording sheet when a user presses a start button provided on the operation unit 4.

  A temperature determination unit 212d (corresponding to a temperature determination unit) acquires temperature information of the fixing roller 531 from a temperature sensor provided in the fixing roller 531, and based on the acquired temperature information, the temperature of the fixing roller 531. Is determined to be equal to or higher than a preset temperature (hereinafter referred to as drive start temperature: for example, 120 ° C.).

  The drive control unit 212e (corresponding to a drive control unit) instructs the polygon drive unit 212f and the main drive unit 212g to start and stop driving based on the determination result by the rotation determination unit 212b. The drive control unit 212e starts heating control for setting the fixing roller 531 to a predetermined temperature (here, 180 ° C.) when an instruction to start printing is received by the receiving unit 212c.

  Specifically, when it is determined by the rotation determining unit 212b that the image is rotating at a preset rotation speed or higher, the drive control unit 212e has received an instruction to start printing by the receiving unit 212c. After that, when the temperature determination unit 212d determines that the temperature of the fixing roller 531 is equal to or higher than the drive start temperature (120 ° C. in this case), the main drive unit 212g is started to drive the transport motor 54M. When the driving unit 212g (= conveyance motor 54M) is in a stable driving state, the polygon driving unit 212f starts to drive the polygon motor 512M.

  In addition, when it is determined by the rotation determination unit 212b that the rotation does not exceed the preset rotation speed, the drive control unit 212e receives the instruction to start printing by the reception unit 212c. The polygon driving unit 212f starts to drive the polygon motor 512M, and the temperature of the fixing roller 531 is equal to or higher than the driving start temperature (here, 120 ° C.) by the preset stop timing (here, the temperature determination unit 212d). The polygon driving unit 212f stops driving the polygon motor 512M (= rotates the polygon mirror 512 inertially) and the main driving unit 212g starts driving the conveyance motor 54M. Furthermore, the main drive section 212g (= conveyance motor 54M) is in a stable drive state. At that point, in which to start driving the polygon motor 512M respect polygon drive unit 212f.

  The polygon drive unit 212f (corresponding to a part of the polygon drive unit) performs drive control of the polygon motor 512M that drives the polygon mirror 512 in accordance with an instruction from the drive control unit 212e.

  The main drive unit 212g (corresponding to a part of the main drive unit) performs drive control of the transport motor 54M that transports the recording paper in accordance with an instruction from the drive control unit 212e. Here, the case where the main drive unit 212g performs drive control of the conveyance motor 54M that conveys the recording paper will be described. However, the main drive unit 212g does not use the polygon motor 512M of the copying machine 100 (for example, a photosensitive drum). The driving control of the driving motor 521) may be performed.

  FIG. 4 is a graph showing an example of heating characteristics and cooling characteristics of the fixing roller 531. The horizontal axis in the figure is the elapsed time, and the vertical axis is the temperature of the fixing roller 531. Moreover, (a) is a graph which shows a heating characteristic, (b) is a graph which shows a cooling characteristic. As shown in the graph G1 of (a), when the initial temperature is 40 ° C., the driving start temperature (120 ° C. in this case) is reached in 6.5 seconds, and the printable temperature (10.5 seconds) ( Here, the temperature reaches 155 ° C. or higher. As shown in graph G2 of (b), when the initial temperature is 196 ° C., the lower limit of the printable temperature (155 ° C. or higher) is reached in 39 seconds.

  FIG. 5 is a flowchart for explaining an example of the operation of the rotation determination unit 212b. The following operations are all performed by the rotation determination unit 212b. Here, it is assumed that the threshold value T0 is set in advance by the threshold value setting unit 212a. First, it is determined whether or not the polygon motor 512M is changed from the driving state (= on) to the driving stop state (= off) (S101). If it is determined that it is not turned off from on (NO in S101), the process is set to a standby state.

  If it is determined that the timer has been turned off from on (YES in S101), the timer starts counting (S103). Then, it is determined whether or not the timer count is equal to or less than the threshold T0 (S105). If it is determined that the timer count is equal to or less than the threshold T0 (YES in S105), the polygon rotation flag is set to ON (S107), and the process returns to step S105. If it is determined that the timer count is not less than or equal to the threshold value T0 (= more than the threshold value T0) (NO in S105), the polygon rotation flag is set to off (S109), and the process ends.

  FIG. 6 is a flowchart illustrating an example of the operation of the CPU 21. First, the receiving unit 212c determines whether or not an instruction to form an image on recording paper has been received (S201). If it is determined that an instruction to form an image on recording paper has not been received (NO in S201), the process is set to a standby state. If it is determined that an instruction to form an image on recording paper has been received (YES in S201), the drive control unit 212e determines whether the polygon rotation flag is on (S203). .

  If it is determined that the polygon rotation flag is on (YES in S203), the temperature determination unit 212d determines whether or not the temperature of the fixing roller 531 is equal to or higher than the drive start temperature (S205). If it is determined that the temperature of the fixing roller 531 is lower than the drive start temperature (NO in S205), the process is set to a standby state. If it is determined that the temperature of the fixing roller 531 is equal to or higher than the drive start temperature (YES in S205), the drive control unit 212e starts driving the carry motor 54M via the main drive unit 212g (S207). .

  Then, the drive control unit 212e determines whether or not the transport motor 54M has reached the stable drive state (S209). If it is determined that the transport motor 54M has not reached the stable drive state (NO in S209), the process is set to a standby state. When it is determined that the transport motor 54M has reached the stable drive state (YES in S209), the drive control unit 212e starts driving the polygon motor 512M via the polygon drive unit 212f (S211). Then, the drive control unit 212e determines whether or not the polygon motor 512M has reached the stable drive state (S213). If it is determined that the polygon motor 512M has not reached the stable drive state (NO in S213), the process is set in a standby state. If it is determined that the polygon motor 512M has reached the stable drive state (YES in S213), printing is started (S229) and the process is terminated.

  If it is determined in step S203 that the polygon rotation flag is off (NO in S203), the drive control unit 212e starts driving the polygon motor 512M via the polygon drive unit 212f (S215). Then, the temperature determination unit 212d determines whether or not the temperature of the fixing roller 531 is equal to or higher than the drive start temperature (S217). If it is determined that the temperature of the fixing roller 531 is lower than the drive start temperature (NO in S217), the process is set to a standby state.

  When it is determined that the temperature of the fixing roller 531 is equal to or higher than the drive start temperature (YES in S217), the drive control unit 212e stops driving the polygon motor 512M via the polygon drive unit 212f (S219). . Then, the drive control unit 212e starts driving the transport motor 54M via the main drive unit 212g (S221). Next, the drive control unit 212e determines whether or not the transport motor 54M has reached the stable drive state (S223).

  If it is determined that the transport motor 54M has not reached the stable drive state (NO in S223), the process is set to a standby state. When it is determined that the transport motor 54M has reached the stable drive state (YES in S223), the drive control unit 212e starts driving the polygon motor 512M via the polygon drive unit 212f (S225). Then, the drive control unit 212e determines whether or not the polygon motor 512M has reached the stable drive state (S227). If it is determined that polygon motor 512M has not reached the stable drive state (NO in S227), the process is set to a standby state. If it is determined that the polygon motor 512M has reached the stable drive state (YES in S227), printing is started (S229) and the process is terminated.

  In this way, based on the determination result of whether or not the polygon mirror 512 is rotating at a speed higher than the preset rotation speed, the polygon motor 512M that drives the polygon mirror 512 and the transport motor 54M that transports the recording paper are used. Since the start and stop of the drive are instructed, the frequency of turning on / off the polygon motor 512M can be suppressed and the startup time can be shortened.

  Whether or not the polygon mirror 512 is rotating at a preset rotation speed or higher based on the elapsed time from when the polygon motor 512M is changed from the driving state (= on) to the driving stop state (= off). Therefore, it is not necessary to detect the rotational speed of the polygon mirror 512, and the apparatus can be simplified.

  Further, the rotational speed of the polygon mirror 512 in the stable drive state is a preset speed, and the elapsed time from the time when the polygon motor 512M is changed from the stable drive state to the drive stop state, and the polygon mirror 512 Since the relationship with the rotation speed is uniquely determined by the device configuration, the polygon mirror 512 rotates at a rotation speed higher than a preset rotation speed according to the elapsed time from when the polygon motor 512M is changed from the drive state to the drive stop state. It can be accurately determined whether or not.

  In addition, when the elapsed time from when the polygon motor 512M is changed from the drive state to the drive stop state is shorter than a preset threshold value T0, it is determined that the polygon motor 512M is rotating at a preset rotation speed or higher. Therefore, accurate determination can be made with a simple configuration.

  Further, since the threshold T0 for the elapsed time is set based on the acceleration characteristic of the polygon motor 512M, an appropriate threshold can be set. That is, by increasing the threshold value T0 as the acceleration characteristics of the polygon motor 512M are better, it is possible to suppress the frequency of turning on and off the polygon motor 512M and shorten the startup time.

  Further, since the elapsed time threshold T0 is set based on the heating characteristics of the fixing roller 531, the appropriate threshold T0 can be set. In other words, the better the heating characteristics of the fixing roller 531, the greater the threshold T0, thereby suppressing the on / off frequency of the polygon motor 512M and shortening the startup time.

  In addition, when it is determined that the polygon mirror 512 is not rotating at a preset rotation speed or higher, the driving of the polygon motor 512M is started when an instruction to form an image on a recording sheet is received. Then, at the preset stop timing, the driving of the polygon motor 512M is stopped, the driving of the transport motor 54M is started, and further, the driving of the polygon motor 512M is started when the transport motor 54M is in a stable driving state. Is started, the startup time can be shortened.

  Further, at the timing when it is determined that the temperature of the fixing roller 531 is equal to or higher than a preset temperature (= drive start temperature: 120 ° C. in this case), the driving of the polygon motor 512M is stopped and the main driving means Since the driving is started, the polygon mirror 512 is accelerated to some extent at the time when the driving of the transport motor 54M is started, so that the activation time can be shortened.

  Further, when it is determined that the polygon mirror 512 is rotating at a speed higher than or equal to a preset rotational speed, the temperature of the fixing roller 531 is preset after an instruction to form an image on a recording sheet is received. When it is determined that the temperature is equal to or higher than the temperature (= drive start temperature: 120 ° C. in this case), the driving of the transport motor 54M is started, and when the transport motor 54M is in a stable driving state, the polygon motor 512M Since driving is started, the frequency of turning on / off the polygon motor 512M can be suppressed.

The present invention can also be applied to the following forms.
(A) In the present embodiment, the case where the main drive unit 212g performs drive control of the transport motor 54M that transports the recording paper has been described. For example, any form may be used as long as the driving control of the photosensitive drum 521 or the driving motor of the fixing roller 531) is performed.

  (B) In the present embodiment, the rotation determination unit 212b determines that the polygon mirror 512 is preliminarily set based on the elapsed time from when the polygon motor 512M is changed from the driving state (= on) to the driving stop state (= off). Although the case where it is determined whether or not it is rotating at a set rotation speed or higher has been described, another method may be used to determine whether or not the polygon mirror 512 is rotating at a preset rotation speed or higher. . For example, the rotational speed of the polygon mirror 512 may be detected to determine whether or not the polygon mirror 512 is rotating at a preset rotational speed or higher.

  (C) In the present embodiment, the case where the threshold value T0 is set in advance by the threshold value setting unit 212a has been described, but the threshold value setting unit 212a is at a predetermined timing (for example, when the power is turned on for the first time every month). The form which sets threshold value T0 may be sufficient. In this case, an appropriate threshold T0 is set according to changes in the acceleration characteristics of the polygon motor 512M, the heating characteristics of the fixing roller 531 and the deceleration characteristics of the polygon mirror 512.

  (D) In the present embodiment, the case where the threshold setting unit 212a sets the threshold T0 based on the acceleration characteristic of the polygon motor 512M, the heating characteristic of the fixing roller 531 and the deceleration characteristic of the polygon mirror 512 has been described. The threshold value T0 may be set based on at least one of the acceleration characteristics of the motor 512M, the heating characteristics of the fixing roller 531 and the deceleration characteristics of the polygon mirror 512.

  (E) In the present embodiment, the drive control unit 212e determines that the temperature determination unit 212d determines that the temperature of the fixing roller 531 is equal to or higher than the drive start temperature (120 ° C. in this case). However, the drive control unit 212e starts driving the transport motor 54M with respect to the main drive unit 212g at a preset timing (for example, after 3 seconds). It is also possible to use a form.

FIG. 1 is a block diagram showing an example of a schematic configuration of an image forming apparatus according to the present invention. FIG. 2 is a configuration diagram illustrating an example of a configuration of a developing unit illustrated in FIG. 1. These are functional block diagrams which show an example of a function structure of the principal part in this invention. These are graphs showing an example of heating characteristics and cooling characteristics of the fixing roller. These are flowcharts explaining an example of the operation of the rotation determination unit. These are the flowcharts which show an example of operation | movement of CPU.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Copy machine 1 Image generation part 2 Control part 21 CPU
212a Threshold setting unit (threshold setting means)
212b Rotation determination unit (rotation determination means)
212c Reception part (part of reception means)
212d Temperature determination unit (temperature determination means)
212e Drive control unit (drive control means)
212f Polygon drive unit (polygon drive means)
212g main drive unit (main drive means)
3 Display part 4 Operation part (a part of reception means)
DESCRIPTION OF SYMBOLS 5 Print processing part 51 Developing unit 511 Laser diode 512 Polygon mirror 512M Polygon motor 52 Photosensitive unit 521 Photosensitive drum 53 Fixing unit 531 Fixing roller 54 Carrying unit 54M Carrying motor

Claims (8)

An image forming apparatus that irradiates a photosensitive drum with a laser beam through a polygon mirror to form a latent image, and forms a toner image corresponding to the formed latent image on a recording sheet.
Polygon driving means for driving the polygon mirror;
Main drive means for driving at least the photosensitive drum;
Rotation determination means for determining whether or not the polygon mirror rotates at a rotation speed higher than a preset value;
Drive control means for instructing the polygon drive means and the main drive means to start and stop driving based on the determination result by the rotation determination means;
An image forming apparatus comprising:   The rotation determining unit determines whether or not the polygon driving unit is rotating at a preset rotation speed or higher based on an elapsed time from the time when the polygon driving unit is changed from the driving state to the driving stop state. The image forming apparatus according to claim 1.   3. The image forming apparatus according to claim 2, wherein the rotation determination unit determines that the image is rotating at a rotation speed equal to or higher than a preset rotation speed when the elapsed time is shorter than a preset threshold value.   The image forming apparatus according to claim 3, further comprising a threshold setting unit configured to set the threshold based on an acceleration characteristic of the polygon driving unit. A fixing roller for fixing the toner image on the recording paper;
The image forming apparatus according to claim 4, wherein the threshold setting unit sets the threshold based on a heating characteristic of the fixing roller. A receiving means for receiving an instruction to form an image on recording paper;
When the drive control means determines that the rotation determination means does not rotate at a rotation speed higher than a preset value,
When the instruction is received by the receiving means, the polygon driving means is started to drive,
At the preset stop timing, the polygon driving unit is stopped driving, the main driving unit is started driving,
6. The image forming apparatus according to claim 5, wherein when the main driving unit is in a stable driving state, the polygon driving unit starts driving. Temperature determining means for determining whether the temperature of the fixing roller is equal to or higher than a preset temperature;
The image forming apparatus according to claim 6, wherein the drive control unit sets the timing at which the temperature determination unit determines that the temperature of the fixing roller is equal to or higher than a preset temperature as the stop timing. . When the drive control means determines that the rotation determination means is rotating at a rotation speed higher than a preset value,
After the instruction is received by the receiving unit, when the temperature determining unit determines that the temperature of the fixing roller is equal to or higher than a preset temperature, the main driving unit starts driving,
The image forming apparatus according to claim 7, wherein the polygon driving unit starts driving when the main driving unit is in a stable driving state.

Images