JP2009075512A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus that can suppress inrush current during a period from the startup to operation. <P>SOLUTION: When the image forming apparatus is started up, the power supply to a fixing device heater and polygon motor is set in an ON state (SP2) at the timing t1 (SP1); and the power supply to a photoreceptor drum motor is set in an ON state, and the power supply to the polygon motor is set in an OFF state (SP4) at the timing t2 (SP3). At the timing t3 (SP5) when the polygon motor is not stopping completely and rotates by a predetermined rotation frequency α, the power supply to the photoreceptor drum is set in the OFF state and the power supply to the polygon motor is set in the ON state (SP6). At the timing t4 (SP7), the image forming apparatus confirms (SP8) operation status in the polygon mirror. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus that forms a latent image by scanning a photosensitive member with a laser beam using a polygon mirror.

  The image forming apparatus irradiates a polygon mirror that rotates at high speed with a laser beam whose light intensity is modulated according to an image forming pattern, and the laser beam varies depending on the instantaneous angle and position of each light deflection surface constituting the polygon mirror. The laser beam is scanned by reflecting in the opposite direction to form a latent image on the photosensitive member. Thereafter, development / fixing processing is performed on the latent image.

  In such an image forming apparatus, after turning on the power or returning from the power saving mode, the fixing heater is warmed up to some extent, and then the operation of the drive system such as the photoconductor, development, and fixing is checked. ing. Thereafter, the operation of the light source is confirmed simultaneously with the operation of the polygon mirror. The operation of the light source is confirmed after confirming the operation of the electric circuit of the substrate.

  The operation confirmation of the polygon mirror is performed in parallel with the operation confirmation of the light source, and the operation confirmation of the light source is not performed until the polygon mirror rotates at the steady rotation speed. For this reason, reducing the time until the rotation speed of the polygon mirror reaches the steady rotation speed and shortening the time until the start of printing is one of the indexes representing the performance of the image forming apparatus.

Japanese Patent Laying-Open No. 2005-198468 (Patent Document 1) discloses a method for changing the output voltage from a motor driving power source to a higher potential higher than a reference potential at the time of starting a motor for rotating a polygon mirror, thereby speeding up the starting. A motor control device is described in which the output voltage from the motor drive power supply is switched to the reference potential after a later desired time has elapsed.
JP 2005-198468 A (Summary)

  However, if a voltage higher than the reference potential is applied to the motor, the electric load of the motor increases, which adversely affects the life of electrical components such as coils and ICs. In addition, the amount of current increases by applying a high voltage to the motor. In addition, an increase in inrush current including a drive system such as a photoreceptor, development, and fixing is adversely affected. As a result, it is not sufficient to apply a voltage higher than the reference potential to the motor for the problem of shortening the warm-up time when the power is turned on.

  Therefore, when the image forming apparatus is started up or returned from the power saving mode, the inrush current is reduced by shifting the power-on timing of the driving system such as the photosensitive member, the fixing device heater, and the polygon motor as shown in FIG. Control is taking place. In FIG. 6, the fixing device heater is turned on at the timing t01 as shown in FIG. 6B, the photosensitive drum motor is turned on at the timing t02, as shown in FIG. 6A, and the photosensitive drum motor is turned on at the timing t03. The body drum motor is turned off, and the polygon motor is turned on as shown in FIG. At timing t04, the fixing device heater is turned off as shown in FIG. 6B, and the polygon motor is turned off as shown in FIG. 6C.

  In this way, by varying the timing of starting the drive system, the inrush current can be reduced and the total amount of current flowing from the power supply device can be suppressed to the upper limit value or less as shown in FIG. However, in the conventional example shown in FIG. 6, since the polygon motor is turned on at timing t03 as shown in FIG. 6C, it must be immediately before timing t04 as shown in FIG. 6E. For example, the rotation speed of the polygon mirror does not become the steady rotation speed. For this reason, the operation check of the polygon mirror is performed after the timing t04, and the time required for the operation check becomes long. Only after the operation is confirmed, the writing operation to the actual photoreceptor itself cannot be performed. If the polygon motor is turned on at timing t01, the time required for the polygon mirror rotation speed to reach the steady rotation speed can be shortened, but the inrush current increases and the total current value may exceed the upper limit value. is there.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image forming apparatus capable of suppressing an inrush current from starting to operating and capable of starting up rotation of an optical deflector at an early stage.

  The present invention provides a first drive system for driving a photosensitive member, a second drive system for driving an optical deflector for forming a latent image, and respective start timings of the first drive system and the second drive system. And an image forming apparatus including control means for reducing the inrush currents of the first and second drive systems by shifting the control unit, and the control means starts, stops and starts the second drive system in advance, and the optical deflector stops. Before the control, the second drive system is controlled to restart.

  Preferably, the control unit restarts the second drive system in response to the optical deflector rotating at a desired rotational speed or more.

  Preferably, a plurality of first drive systems are provided, and the control unit starts and stops the plurality of first drive systems a plurality of times at different timings.

  Preferably, the control means includes any one of the plurality of first drive systems and the power supply of the second drive system so that the total value of the inrush currents flowing in each of the plurality of first drive systems does not exceed the upper limit value. Start and stop in synchronization with.

  Preferably, the plurality of first driving systems include a developing roller driving system and a fixing driving system.

  Preferably, the desired number of rotations is determined from at least the activation time of the optical deflector.

  According to the present invention, the inrush current from the start to the operation can be suppressed by shifting the start and stop timings of the first and second drive systems, and before the optical deflector stops. By restarting the second drive system, the rotation of the optical deflector can be started at an early stage.

  FIG. 1 is a block diagram of an image forming apparatus according to an embodiment of the present invention. In FIG. 1, an image forming apparatus 1 is, for example, a digital multi-function peripheral, a printer, or a facsimile machine, and includes a control unit 2 that operates as a control unit, a reading unit 3 that is connected to the control unit 2, and an operation unit. 4, a display unit 5, a printing unit 6, and a hard disk (HDD) 7, and a power supply device 8 that supplies power to each unit is provided. The reading unit 3 reads an image from a document, and the operation unit 4 inputs the number of copies and the like by a user operation. The display unit 5 displays the number of copies and selectable paper sizes.

  The printing unit 6 includes, as main components, a photosensitive drum motor 9 as a first drive system, a fixing device heater 10, and a polygon motor 11 as a second drive system. The photoconductive drum motor 9 rotates the photoconductive drum. The fixing device heater 10 is provided to bring the fixing device to a fixing temperature, and the polygon motor 11 included in the optical deflector rotates the polygon mirror.

  FIG. 2 is a flowchart for explaining the power-on / off operation of the drive system in the image forming apparatus according to the embodiment of the present invention. FIG. 3 is a timing for turning on / off the power supplied to the drive system. FIG. 4 is a diagram for explaining the timing for restarting the polygon motor 11.

  When the image forming apparatus 1 is activated or returned from the power saving mode, the processing shown in FIG. 2 starts. The power saving mode is a mode in which the power supply of the main drive unit is turned off to stop the power saving in order to save power. Hereinafter, the activation is not only when the power is turned on, but also when returning from the power saving mode. Shall be included. In step SP1 (abbreviated as SP in the figure), the control unit 2 determines whether or not the timing t1 of the predetermined activation time has been reached by a built-in timer, and if it is determined that it has reached t1, step SP2 3B, the power supply to the fixing device heater 10 is turned on as shown in FIG. 3B, and before the operation of the polygon mirror is confirmed as shown in FIG. The power supply to the polygon motor 11 is turned on to start.

  At this time, the amount of current flowing from the power supply device 8 rises at timing t1 as shown in FIG. 3D, but does not exceed the upper limit value. Here, the upper limit value refers to a current value that can be supplied by the power supply device 8. When the power supply of the fixing device heater 10 is turned on, the temperature of the fixing device rises to the fixing temperature. When the polygon motor 11 is activated, the rotational speed of the polygon mirror increases during the section A as shown in FIG.

  In step SP3, it is determined whether or not the timing t2 is reached. When it is determined that the timing t2 is reached, in step SP4, as shown in FIG. 3A, the power supply to the photosensitive drum motor 9 is turned ON. At the same time, as shown in FIG. 3C, the power supply to the polygon motor 11 is turned off.

  In step SP5, it is determined whether or not the timing t3 has come. When it is determined that the timing t3 is reached, in step SP6, the power supply to the photosensitive drum 9 is turned off and the power supply to the polygon motor 11 is turned on. Even when the power supply to the polygon motor 11 is turned on, the power supply to the photosensitive drum motor 9 is cut off, so that the current amount of the power supply 8 is below the upper limit value. Thus, by rotating the polygon motor 11 in advance, as shown by the broken line k in FIG. 3E, when the polygon motor 11 is started from a completely stopped state without starting in advance. Compared to the section B, the activation time of the image forming apparatus can be shortened.

That is, to the polygon motor 11 rotate stably at time _{T 1,} as shown in FIG. 4, it is necessary to determine the start time ΔT _PM = _T 1 _{-T PM} to restart the polygon motor 11. The startup time [Delta] T _PM at the timing t3 shown in FIG. 3 (e), so that the inertial rotation at a desired rotation number alpha, is determined by determining the interval A. The setting of the desired rotational speed α is determined from the startup time of the polygon motor 11.

  In step SP7, it is determined whether or not the timing t4 has come. Since the polygon mirror is rotated at the steady rotation speed at the timing t4, the operation of the polygon mirror can be confirmed in step SP8, and the copying can be performed thereafter.

  As described above, according to this embodiment, after starting, the polygon motor 11 is turned on and off, so that the polygon mirror rotates to some extent even if the power is turned off. Since the polygon motor 11 is restarted again when the motor 11 is rotating at a desired rotational speed α that is not completely stopped, the rotational speed of the polygon mirror is quickly increased until the steady rotational speed is confirmed at the time of starting confirmation. Can be raised. As a result, the time required for checking the operation of the polygon mirror can be shortened, and as a result, the transition time from the standby time such as when the power is turned on or when returning from the power saving mode can be shortened.

Incidentally, activation time T ₁ of the polygon motor 11 since they depend specifications of the image forming apparatus, the startup time of the polygon motor 11 is measured at the start of the image forming apparatus, with the relationship of FIG. 4, based on the information The desired rotational speed α may be calculated and stored in the HDD 7.

  Further, at the time of start-up, power supply ON / OFF of the photosensitive drum motor 9 and power supply ON / OFF of the fixing device heater 10 are not simultaneously performed, and are synchronized with either ON / OFF. Since the power supply of the polygon motor 11 is turned on and off a plurality of times, the inrush current can be controlled so as not to exceed the upper limit value of the power capacity.

  FIG. 5 is a diagram showing the timing for turning on and off the power supplied to the drive system of the image forming apparatus according to another embodiment of the present invention. In the embodiment shown in FIG. 3, the photoconductor drum motor 9, the fixing device heater 10, and the polygon motor 11 are synchronized to control ON / OFF of the power supply. In this embodiment, the photoconductor drum is controlled. The three drive systems A, B, and C such as the motor 9, the transfer drum, and the transfer roller, the fixing device heater 10, and the polygon motor 11 are controlled to be turned on and off in synchronization.

  That is, the power supply to the fixing device heater 10 and the polygon motor 11 as shown in FIG. 5 (e) are turned on at timing t1, and the timing shown in FIG. 5 (a) is shown at timing t2. Thus, the power supply to the drive system A is turned on, and the power supply to the polygon motor 11 is turned off. At timing t3, the power supply to the drive system A is turned off, the power supply to the drive system B is turned on as shown in FIG. 5B, and the power to the polygon motor 11 is turned on as shown in FIG. Turn on the supply. At timing t4, the power supply to the polygon motor 11 is turned off, and the power supply to the drive system C is turned on as shown in FIG.

  At timing t5, the power supply to the drive system C is turned off, and the power supply to the polygon motor 11 is turned on. At timing t6, the power supply to the fixing device heater 10 and the polygon motor 11 is turned off.

  As described above, since the power supply to the polygon motor 11 is turned on and off three times during the period from the start of the timing t1 to the timing t6, each of the power supplies 8 is connected to the polygon motor 11 as shown in FIG. The total value of the inrush current supplied to the configuration can be suppressed to the upper limit value or less, and the rotation speed of the polygon mirror can be constantly maintained at a value close to the steady rotation speed as shown in FIG. For this reason, when the operation of the polygon mirror is checked after startup, the polygon mirror is not completely stopped and is rotated at a desired rotation speed, so that the time required to reach the steady rotation speed can be shortened. In addition, it is possible to shorten the transition time to a desired operation from the standby time such as when the power is turned on or when returning from the power saving mode.

  There may be four or more drive systems.

  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 of an image forming apparatus according to an embodiment of the present invention. 3 is a flowchart for explaining ON / OFF operation of a drive system power supply in the image forming apparatus according to the embodiment of the present invention; FIG. 4 is a diagram illustrating timings for turning on and off the power supplied to the drive system in the image forming apparatus according to the embodiment of the present invention. It is a figure for demonstrating time (DELTA) _TPM which starts a polygon motor. It is a figure which shows the timing which turns ON / OFF the power supplied to the drive system of the image forming apparatus in other embodiment of this invention. FIG. 10 is a diagram for explaining control for shifting timings of turning on / off a drive system such as a photosensitive drum, a heater of a fixing device, and a polygon motor in a conventional image forming apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Image forming apparatus, 2 Control part, 3 Reading part, 4 Operation part, 5 Display part, 6 Printing part, 7 HDD, 8 Power supply device, 9 Photosensitive drum motor, 10 Fixing device heater, 11 Polygon motor.

Claims (6)

A first drive system for driving the photoreceptor;
A second drive system for driving an optical deflector that forms a latent image;
An image forming apparatus including control means for reducing inrush currents of the first and second drive systems by shifting respective start timings of the first drive system and the second drive system;
The image forming apparatus, wherein the control unit starts and stops the second drive system in advance, and controls the second drive system to restart before the optical deflector stops.   The image forming apparatus according to claim 1, wherein the control unit restarts the second drive system in response to the optical deflector rotating at a predetermined rotational speed or more. A plurality of the first drive systems are provided,
The image forming apparatus according to claim 1, wherein the control unit starts and stops the plurality of first drive systems a plurality of times at different timings.   The control means may be configured so that any one of the plurality of first drive systems and the second drive system does not exceed an upper limit value so that a total value of inrush currents flowing through the plurality of first drive systems does not exceed an upper limit value. The image forming apparatus according to claim 3, wherein the image forming apparatus is activated and deactivated in synchronization with a power source.   5. The image forming apparatus according to claim 3, wherein the plurality of first driving systems include a developing roller driving system and a fixing driving system. 6. The image forming apparatus according to claim 2, wherein the predetermined number of rotations is determined from at least an activation time of the optical deflector.

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